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Barium and strontium uptake into larval protoconchs and statoliths of the marine neogastropod Kelletia kelletii
Abstract
The trace elemental composition of calcified larval hard parts may serve as useful tags of natal origin for invertebrate population studies. We examine whether the trace metal barium (Ba) deposits into the calcium carbonate matrix of molluscan larval statolith and protoconch in proportion to seawater Ba concentration at two temperatures (11.5 and 17°C). We also examine strontium (Sr) uptake as a function of temperature. Using encapsulated larvae of the marine gastropod, Kelletia kelletii, reared in the laboratory under controlled conditions, we demonstrate a significant inverse effect of temperature and a positive effect of seawater Ba/Ca ratio on Ba incorporation into larval carbonates. Ba/Ca partition coefficients (DBa) in protoconch were 1.13 at 11.4°C and 0.88 at 17.1°C, while DBa in larval statolith measured 1.58 at 11.4°C and 1.29 at 17.1°C. Strontium incorporation into statoliths is also inversely affected by temperature, but there was a significant positive effect of temperature on Sr incorporation into protoconch. These data suggest larval statoliths and protoconchs can meaningfully record variation in seawater physical and chemical properties, and, hence, have potential as natural tags of natal origin.
... In this species, and at this geographic region, statolith growth rings are claimed to be actual winter marks, i.e. produced annually during the cold season (Barroso et al. 2005a, b). Furthermore, a higher deposition of strontium (Sr) in N. reticulatus statolith growth rings was recently reported (Galante-Oliveira et al. 2014) and attributed to the negative correlation between this element concentration in statoliths and temperature (Zacherl et al. 2003b;Lloyd et al. 2008). In the light of these findings, the use of Sr to calcium (Ca) ratio across N. reticulatus statoliths was tested in an effort to: (1) identify the annual growth rings (ARs) in specimens of known age (which expectedly have a known number of periodic rings, theoretically equal to the specimen age in years) and (2) distinguish these actual growth increments from disturbance rings (DRs) that, being produced regardless of temperature, should not be chemically labelled by a temperature-dependent proxy. ...
... Additionally, as magnesium (Mg) and barium (Ba) concentrations in some biocarbonates have also been shown as proxies of ambient temperature (e.g. Zacherl et al. 2003b;Arkhipkin et al. 2004;Richardson et al. 2005b;Zumholz et al. 2007;Marohn et al. 2011), their abundances relative to Ca were also monitored. ...
... As periodic growth rings in N. reticulatus statoliths were proved to be formed annually as a result of the seasonal variation in temperature Chatzinikolaou and Richardson Fig. 4 Alignment of the intensities of 48 Ca and 88 Sr 48 Ca −1 along the ablated profile with the respective statolith picture for a statolith extracted from one specimen from C2, and b statolith from one specimen selected from C3+, corresponding to a worst-case scenario with ARs and DRs not distinguishable by simple visual inspection. Black dashed lines are the limits of the region ablated on the statolith; black dotted lines match 88 Sr 48 Ca −1 ratio peaks and the MR; grey dotted lines show the correspondence between 88 Sr 48 Ca −1 ratio peaks and statolith ARs 1 3 2007; Galante- Oliveira et al. 2014), and given the fact that an increased amount of Sr in statolith growth rings was recently reported for this species (Galante-Oliveira et al. 2014) and attributed to a higher rate of this element incorporation at low temperatures in gastropod statoliths (Zacherl et al. 2003b), it is plausible to consider that the elevated amount of Sr periodically detected in N. reticulatus statoliths constitutes a chemical tag of the rings formed annually during the seasonal decrease in temperature. This assumption is supported by our analysis of the statoliths extracted from 2-year-old specimens (from C2 in July 2013), with the majority (70 %) revealing 3 periodic cycles of 88 Sr 48 Ca −1 that matched the MR and another 2 visible growth rings. ...
Gastropods retain less obvious periodic growth marks on calcified structures than individuals in other groups (e.g. bivalves, cephalopods, fish), a fact that has hampered age estimation in this Class. Nevertheless, a model of age estimation for the gastropod Nassarius reticulatus is possible based on the annual growth rings deposited in statoliths during the winter. These spherical aragonitic carbonate structures are located inside the statocysts and contain a characteristic microstructural pattern of concentric rings. However, this pattern can be biased by the formation of nonperiodic disturbance rings (DRs). In Aveiro (NW Portugal), an increased frequency of DRs was reported in statoliths of specimens inhabiting the Ria de Aveiro lagoon (a highly dynamic environment), when compared with specimens collected from the relatively environmentally stable adjacent offshore area. One approach to resolve annual growth in organically precipitated carbonates is to find a chemical signature within the microstructure that faithfully records changes in seasonal environmental parameters. In this contribution, we have analysed the Sr Ca-1 variation along statolith sections by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) as a proxy to resolve seasonal cycles of temperature, allowing the identification of annual growth rings. Combining this information with size-frequency distributions of shell height, we found strong evidence that the rings chemically labelled with 88Sr 48Ca-1 peaks are formed annually during the cold season. Hence, LAICPMS allows not only the detection of visible rings but also the distinction between rings formed at low temperatures (i.e. a periodic seasonal signature) and those of disturbance (not characterised by increased 88Sr 48Ca-1). There is also clear evidence that the 88Sr 48Ca-1 peaks become less conspicuous from the nucleus to the statolith edge, leading to a loss of discriminatory power for the identification of older age rings. Nevertheless, this new method allows the accurate age estimation of N. reticulatus specimens and is liable to be applied in a wide range of gastropods after specific validation
... Specifically, exothermic reactions have a negative enthalpy and are predicted to be preferred at colder temperatures. Empirical evidence supports equilibrium thermodynamic predictions by demonstrating an inverse temperature effect regarding Ba incorporation into gastropod and cephalopod statoliths (Zacherl et al. 2003, Zumholz et al. 2007). However, as suggested by Zacherl et al. (2003) and demonstrated conclusively by Lorrain et al. (2005), kinetic effects such as the precipitation rate of cations to the crystal surface may override thermodynamic predictions to further influence elemental incorporation into molluscan biominerals. ...
... Empirical evidence supports equilibrium thermodynamic predictions by demonstrating an inverse temperature effect regarding Ba incorporation into gastropod and cephalopod statoliths (Zacherl et al. 2003, Zumholz et al. 2007). However, as suggested by Zacherl et al. (2003) and demonstrated conclusively by Lorrain et al. (2005), kinetic effects such as the precipitation rate of cations to the crystal surface may override thermodynamic predictions to further influence elemental incorporation into molluscan biominerals. Finally, interactions between multiple environmental factors can influence elemental incorporation and species-specific differences have also been reported (Swearer et al. 2003, Elsdon & Gillanders 2004, Zumholz et al. 2007. ...
... Finally, provided the former assumptions are found to be true, chemical analysis of biominerals formed during larval development and retained through subsequent ontogeny is critical to reconstruct larval origin and subsequent dispersal trajectory (DiBacco & Levin 2000). Such structures are observed in fish (otoliths), gastropods (statocyst and protoconch), and bivalves (prodissoconch) among others (Campana 1999, Zacherl et al. 2003, Zacherl 2005, Becker et al. 2007). ...
The elemental signature of trace and minor elements within biominerals has been used to investigate the larval dispersal of bivalves. We investigated the potential of this technique by examining elemental signals in juvenile shells of the hard clam Mercenaria mercenaria within an estuarine-lagoonal system near Cape Lookout, North Carolina, USA. We assessed the spatial distinction (similar to 12 to 40 km) and temporal stability (fall versus spring) of elemental concentrations using inductively coupled plasma mass spectrometry (ICP-MS). Twelve minor and trace elements were present at detectable levels in all shell samples: calcium (Ca), manganese (Mn), aluminum (Al), titanium (Ti), cobalt (Co), copper (Cu), barium (Ba), magnesium (Mg), zinc (Zn), lead (Pb), nickel (Ni), and strontium (Sr). Discriminant function analyses (DFA) using metal to Ca ratios as independent variables correctly assigned hard clams to their site of collection with 100% success from both fall and spring sampling events. Mn: Ca ratio proved to be the most effective discriminator explaining 91.2 and 71.9% of our among-group variance, respectively. Elemental concentrations within juvenile shell differed temporally. A combined DFA approach using shell from both sampling events obtains a classification success of 81.9%. Mn: Ca ratio explained the bulk of among group variance (89.9%) and was consistently different among water masses during each season. Our results demonstrate for the first time the existence of small-scale spatial differences (similar to 12 km) in the elemental chemistry of juvenile bivalve shell exclusively within an estuarinelagoonal system. Our results suggest that the validation of a similar chemical signal of M. mercenaria larval shells is possible and may be used to trace the dispersal trajectory of this economically important species.
... Theoretically, geochemical tagging approaches could characterize the tags of developing larvae from all possible sources, but this potential has not been realized (Campana 1999, Munch & Clarke 2008, Neubauer et al. 2010. Natural geochemical tags, such as otoliths (Campana 1999) and statoliths (Zacherl et al. 2003, Zacherl 2005, are biogenic carbonates, CaCO 3 crystals enmeshed within a protein matrix, that begin forming in the embryo at its birth location (Chia et al. 1981). Layers are continually added throughout the embryo's life and become permanently incorporated into the structure. ...
... obs.), where females deposit benthic egg capsules (Rosenthal 1970). Embryos brood within egg capsules, developing statoliths after 15 to 19 d (Zacherl et al. 2003). Veligers hatch after 30 to 34 d (Rosenthal 1970). ...
... We grouped sites into 3 distinct geographic regions a priori (north of Point Conception [North], Southern California Bight [Bight] and Baja California [Baja]) based on topography and oceanographic conditions (Zacherl et al. 2003, Zacherl 2005 (Table 1). The colder California Current bathes sites north of Point Conception. ...
Using calcified structures as natural geochemical tags to estimate levels of population connectivity is becoming increasingly common. However, the technique suffers from several logistical and statistical problems that constrain its full application. Foremost is that only a subset of potential sources is sampled, often compounded by under-sampling within locations at an overly coarse spatial scale. This introduces unknown error and prevents the creation of a rangewide connectivity matrix. To address this issue, we analyzed the natural geochemical tags of embryonic statoliths in the whelk Kelletia kelletii (Forbes, 1850). We sampled from 23 sites over the entire geographic range in 2004 and 2005 from Monterey (California, USA) (36°N) to Isla Asunción, (Baja California, Mexico) (27°N). We then used geospatial statistics (kriging) to make continuous along-coast maps of embryonic statolith chemistry. This allowed us to estimate chemistry at unsampled locations. We used this new continuous assignment method to estimate the spatial error associated with assignment by the classic method of discriminant function analysis (DFA). Then, we compared the performance of the 2 methods at classifying unknown embryonic statoliths. We found large spatial errors often associated with DFA assignments, even when traditional DFA accuracy assessments indicated the method was performing well. The continuous method provided an improved assessment of uncertainty in assignments. It outperformed the DFA method in classifying unknown embryos to the vicinity of their true source. Geospatial statistics also provided useful information on other range-wide variables, such as adult reproductive abundance. As a proxy for larval supply, such information can aid future assignments of recruits. Our combined analyses help inform sampling designs and motivate the development of a new approach for population connectivity studies.
... Nuclide concentrations were calibrated against a carbonate-optimized inhouse liquid standard for Ba/Ca (342.0 μmol/mol ± 3.4 (1.0% RSD)) (Zacherl et al., 2003). A solid glass (NIST 612) and carbonate (USGS MACS3) standard reference materials were run periodically to check analytical precision or repeatability. ...
... Thus, a freshwater-related mechanism (via an assumed inverse relationship between salinity and seawater Ba/Ca ratios; e.g., Gillikin et al. (2006)) cannot be invoked to explain the observed Ba/Ca shell peaks. Temperature has been reported to be positively related to Ba/Ca shell in larval oysters (Carson, 2010) and negatively related to Ba/Ca shell in larval gastropods (Zacherl et al., 2003). In this study, temperature is weakly negatively correlated with Ba/Ca shell and no temperature deviation coincided with the observed major Ba/Ca peak. ...
... Ba/Ca variations in biogenic carbonates have been attributed to a plethora of environmental and biological factors including proximity to riverine and groundwater supply (Shaw et al., 1998;Carroll et al., 2009), seawater temperature (Zacherl et al., 2003(Zacherl et al., , 2009Carson, 2010), gonad development and spawning (Gillikin et al., 2006), seawater Ba/Ca concentrations , and diatom abundance . The inverse relationship between salinity and Ba/Ca seawater is reflected in Ba/Ca shell , for example, Gillikin et al. (2006) found a negative relationship between salinity and background Ba/Ca shell in estuarine-reared Mytilus edulis shells. ...
... First described by Clarke in 1966 [1], statoliths are deposits found in squid and other cephalopods that are necessary for equilibrium orientation and are composed of aragonite calcium carbonate similar to that found in foraminifera, corals, gastropod and bivalve shells, and fish otoliths [2][3][4][5][6][7][8][9]. In cephalopods, statoliths begin forming in the statocysts, cavities in the cranial cartilage, before hatching and continue growing after hatching by the daily deposition of an organic rich layer followed by an organic poor layer [7,[10][11]. ...
... Many studies have shown that the patterns and levels of trace elements found in carbonates can be correlated to environmental conditions experienced by an individual or to their feeding behaviors [2-3, 6, 16-17]. The relationship between trace elements in biologically secreted calcified structures and environmental conditions enables the reconstruction of an individual's life history or can be used to distinguish between populations that experience different environments [3,6,[17][18][19][20][21][22]. Additionally, trace elemental studies can be used to compliment and strengthen DNA or length-frequency type studies [19,23]. ...
... Additionally, trace elemental studies can be used to compliment and strengthen DNA or length-frequency type studies [19,23]. For thorough reviews and examples of the power and scope and background of biological carbonate chemistry studies see Arkhipkin [24], Campana [25], Campana and Thorrold [24], Smith et al. [2], Zacherl et al. [3], and Zumholz et al. [20]. ...
Major hindrances for most scientific studies involve a lack of funding, sampling, or equipment. Without large, high resolution sample sets spanning significant spatial scales, long temporal scales, or both, it can be difficult to discern accurate results. This can be the case for some population studies and fisheries management efforts. One novel approach to squid population studies involves harvesting statoliths, but the power of the studies is limited by the scales at which samples are collected. Approaches that involve the characterization of trace elemental chemistry in these aragonite structures could provide a better understanding of the life cycles and behaviors of targeted fisheries species than the common practice of length-frequency studies. Often statoliths are not collected and the absence of consistently periodic or geographically distinct samples potentially limits large scale population studies. One possible reason statoliths are not always removed may be the lack of a thorough, clearly illustrated instructional method on dissection of the statoliths from the cranial cartilage. In an effort to encourage sampling of statoliths, previously published methods are improved upon in this work by including a description of the dissection of the statoliths using layman terms accompanied by detailed photographs. The methods were tested successfully with the Ommastrephid squid Dosidicus gigas and the statoliths obtained will be used to examine trace element variations determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS).
... Using the trace elemental composition of invertebrate mineralized parts as proxies for natal source relies on the assumption that spatial variation in the physical and chemical properties of seawater will somehow be reflected in the elemental composition of the invertebrate hard part, as has been demonstrated with fish otoliths (Radtke & Shafer 1992, Secor et al. 1995, Bath et al. 2000. Zacherl et al. (2003c) generated the first such evidence for larval protoconchs and statoliths (both composed of aragonite) of a marine gastropod whelk. In a culture study examining uptake of Ba by Kelletia kelletii larval hard parts, both statoliths and protoconchs incorporated more Ba as the seawater Ba concentration increased. ...
... Furthermore, there was an inverse temperature effect, with greater Ba incorporation at colder temperatures. Additional culture studies with K. kelletii and other molluscan larvae (e.g. the estuarine opisthobranch Alderia modesta) have generated similar results for Sr (Zacherl et al. 2003c) and Mg (D. C. Zacherl unpubl.). The combined results suggest that these calcified structures, like foraminifera tests ) and otoliths (Bath et al. 2000), can reliably record information about the physical and chemical characteristics of seawater. ...
... I used National Institute of Standards and Technology (NIST-612) glass standards as reference materials from which I could estimate the precision of the laser-ablation method. Elemental concentrations were quantified using a matrix-matched standard solution instead of the NIST standard, since the NIST glass lacks the aragonite-dominated matrix of statoliths (see Zacherl et al. 2003c for discussion of the strengths and weaknesses associated with this analytical approach); 10 individual larval statoliths per brood were analyzed. The element menu for statolith analyses comprised Ca, Mg, Sr, Ba, Pb, Mn, Ce, and Zn. ...
Trace elements in larval hard parts may serve as useful tags of natal origin in invertebrate population studies. Using field-collected encapsulated veliger larvae of the marine gastropod Kelletia kelletii, this study examined the extent of spatial and temporal variation in the elemental composition of larval parts formed at the natal source. For both protoconchs and statoliths, results of multivariate analyses of variance (MANOVA) indicated that the elemental compositions show significant among-site and among-region differences. Linear discriminant-function analysis (DFA) correctly classified 89% of protoconchs and 80% of statoliths to their region of formation. However, there were significant interannual differences in elemental composition for statoliths at 2 sites and for protoconchs at 3 sites over a 3 yr period. Despite within-site interannual differences, the elemental compositions of hard parts formed during different years resembled one another to such a degree that a DFA generated with a single year's data could correctly predict the region of formation for 83.9% of statoliths and 82.5% of protoconchs formed in other years. A comparison of magnesium (Mg), strontium (Sr) and barium (Ba) incorporation patterns with per-site temperature profiles indicated statistically significant positive relationships between temperature and Mg and Sr incorporation into protoconchs, and inverse relationships between temperature and Sr (statoliths) and Ba (both proto-conchs and statoliths) incorporation. These data, together with results from other studies, suggest that larval statoliths and protoconchs can meaningfully record variation in the physical and chemical properties of seawater and, hence, have potential as natural tags of natal origin.
... Fowler et al. 1995, Hoff & Fuiman 1995, Bath et al. 2000, Arai et al. 2003, Bath Martin et al. 2004) and adult mollusc shells (e.g. Rucker & Valentine 1961, Dodd 1965, Lerman 1965, Dodd & Crisp 1982, Pitts & Wallace 1994, Lazareth et al. 2003, Zacherl et al. 2003b. For mollusc larvae, however, shell uptake has been examined only in 1 gastropod (Zacherl et al. 2003b) and in no bivalves. ...
... Rucker & Valentine 1961, Dodd 1965, Lerman 1965, Dodd & Crisp 1982, Pitts & Wallace 1994, Lazareth et al. 2003, Zacherl et al. 2003b. For mollusc larvae, however, shell uptake has been examined only in 1 gastropod (Zacherl et al. 2003b) and in no bivalves. We explored the relationships between temperature and salinity and Mg:Ca, Mn:Ca, Sr:Ca, Ba:Ca, and Pb:Ca based on the demonstrated utility of these elements in previous uptake experiments. ...
... During analyses we monitored 25 Mg, 55 Mn, 48 Ca, 88 Sr, 114 Cd, 138 Ba, and 208 Pb in low-resolution mode. These elements were chosen because of their previous use in successful elemental tagging studies (Kalish 1989, Elsdon & Gillanders 2002, Zacherl et al. 2003b, Bath Martin & Thorrold 2005. Molar ratios of each element to Ca (hereafter E:Ca) were calculated using mass bias corrections calculated from calibration standards. ...
The chemical composition of biogenic carbonate has great potential to serve as a natural tag in studies of marine population connectivity. Yet the degree to which carbonate chemistry reflects ambient water composition may be influenced by environmental parameters, physiology, and uptake kinetics. We explored the effects of temperature and salinity on the uptake of elements into shells of larval and juvenile softshell clams Mya arenaria. Clams were reared under controlled conditions using combinations of temperatures (15, 20, and 24°C) and salinities (22 and 30‰) commonly encountered in their natural habitat. We analyzed the ratios of a suite of elements (Mg, Mn, Sr, Ba and Pb) to Ca in seawater and shells using solution-based inductively coupled plasma-mass spec- trometry (ICP-MS). Elemental ratios were translated into discrimination coefficients (Delement) to account for water chemistry variability among treatments. For larval shell, we found that DMn was lower in the low-temperature treatment than at higher temperatures, had mixed results for correla- tions with salinity, and exhibited an interactive effect between salinity and temperature. We also found that DBa of larval shell was higher in the 15°C treatment than at the other 2 temperatures. In juvenile shell, we found a temperature effect for DMn, however the exact relationship was unclear because DMn was higher in the mid-temperature treatment than either the low- or high-temperature treatments. DSr was negatively correlated with salinity in juveniles, with evidence of an interactive effect for temperature and salinity. DBa and DPb were both higher in juveniles in the low-temperature treatment than in the 2 higher temperatures. When discrimination coefficients significantly differed based on ANOVA, we used post hoc comparisons to further explore the effects of temperature and salinity. Correlation analyses showed that uptake differed significantly between larval and juvenile M. arenaria shell for all elements, with no predictable relationship in shell uptake between the 2 stages except for DBa. All of the elements examined in this study have the potential to be useful in tagging studies where geographic variability in temperature, salinity or elemental concentrations exists, although caution should be used to ensure any biological interactions with these variables are accounted for in data interpretation.
... Six extant species and one subspecies of Penion are currently recognised from New Zealand (Powell, 1979;Spencer et al., 2017), with another two endemic species from Australian waters (Ponder, 1973). A species of Kelletia is recognised from the coast of southern California, USA and Baja California, Mexico (Zacherl et al., 2003a;Vendetti, 2009), and another occurs off Japan (Zacherl et al., 2003b;Hayashi, 2005;Kim et al., 2012;Hwang et al., 2014). Penion and Kelletia are hypothesised to be closely related based on shell morphology (Ponder, 1973), and short-length sequence data (Hayashi, 2005), which we test using mitochondrial genomic and nuclear DNA sequence data. ...
... These genera are dominated by New Zealand taxa, with the exception of Antarctoneptunea and Kelletia. Kelletia is restricted to the Sea of Japan and the Pacific coast of Honshu (Zacherl et al., 2003b;Hayashi, 2005;Kim et al., 2012;Hwang et al., 2014), and southern California, USA and Baja California, Mexico (Zacherl et al., 2003a;Vendetti, 2009). Species of Pareuthria and Antarctoneptunea aurora (Hedley, 1916), the type species of the genus, are restricted to the polar circle of Antarctica (Dell, 1972;Oliverio and Modica, 2010;Pastorino, 2016). ...
Under current marine snail taxonomy, the majority of whelks from the Southern Hemisphere (Buccinulidae) are hypothesised to represent a monophyletic clade that has evolved independently from Northern Hemisphere taxa (Buccinidae). Phylogenetic analysis of mitochondrial genomic and nuclear ribosomal DNA sequence data indicates that Southern Hemisphere taxa are not monophyletic, and results suggest that dispersal across the equator has occurred in both directions. New Zealand buccinulid whelks, noted for their high endemic diversity, are also found to not be monophyletic. Using independent fossil calibrations, estimated genetic divergence dates show remarkable concordance with the fossil record of the Penion and Kelletia. The divergence dates and the geographic distribution of the genera through time implies that some benthic marine snails are capable of dispersal over very long distances, despite varied developmental strategies. Phylogenetic results also indicate that one species, P. benthicolus belongs in Antarctoneptunea.
... Statoliths were mounted on double-sided tape (Scotch TM ), attached to a slide and prepared for laser ablation. The chemical composition of mounting tape was determined by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) [75]; all elemental counts from the tape were at least three orders of magnitude lower than counts found in statoliths. Statolith lengths ranged from 65 to 130 µm. ...
... The laser was set to the spot beam mode at 40% power and a frequency of 20 Hz. Consistent plasma conditions were maintained using 1% HNO 3 during analysis of standards, on instrument blanks and on laser-ablated samples [75]. Instrument sensitivity was monitored measuring indium (In) and was approximately 1 × 10 6 counts·s −1 for 1 ppb. ...
Spawning market squid lay embryo capsules on the seafloor of the continental shelf of the California Current System (CCS), where ocean acidification, deoxygenation and intensified upwelling lower the pH and [O2]. Squid statolith geochemistry has been shown to reflect the squid’s environment (e.g., seawater temperature and elemental concentration). We used real-world environmental levels of pH and [O2] observed on squid-embryo beds to test in the laboratory whether or not squid statolith geochemistry reflects environmental pH and [O2]. We asked whether pH and [O2] levels might affect the incorporation of element ratios (B:Ca, Mg:Ca, Sr:Ca, Ba:Ca, Pb:Ca, U:Ca) into squid embryonic statoliths as (1) individual elements and/or (2) multivariate elemental signatures, and consider future applications as proxies for pH and [O2] exposure. Embryo exposure to high and low pH and [O2] alone and together during development over four weeks only moderately affected elemental concentrations of the statoliths, and uranium was an important element driving these differences. Uranium:Ca was eight-times higher in statoliths exposed to low pHT (7.57–7.58) and low [O2] (79–82 µmol·kg⁻¹) than those exposed to higher ambient pHT (7.92–7.94) and [O2] (241–243 µmol·kg⁻¹). In a separate experiment, exposure to low pHT (7.55–7.56) or low [O2] (83–86 µmol·kg⁻¹) yielded elevated U:Ca and Sr:Ca in the low [O2] treatment only. We found capsular effects on multiple elements in statoliths of all treatments. The multivariate elemental signatures of embryonic statoliths were distinct among capsules, but did not reflect environmental factors (pH and/or [O2]). We show that statoliths of squid embryos developing inside capsules have the potential to reflect environmental pH and [O2], but that these “signals” are generated in concert with the physiological effects of the capsules and embryos themselves.
... An analysis of statolith microstructure can even reveal the number of spawning events squid may experience (Arkhipkin 2005). Following successful applications of trace elements and isotopes in coral skeletons (Beck et al. 1992), bivalve shells (Becker et al. 2005), gastropod statoliths (Zacherl et al. 2003) and especially fish otoliths (Campana 1999), hard structures in cephalopod such as beaks (Cherel and Hobson 2005), cuttlebone (Bettencourt and Guerra 1999), shell (Lukeneder et al. 2008), stylet (Doubleday et al. 2008a), and statolith (Ikeda et al. 2003) have been increasingly used in distinguishing cephalopod population structures, investigating possible migratory routes and reconstructing habitat environment (Liu et al. 2010). Trace element is considered as a potential supplement to more commonly used genetic methods determining cohort and population structures (Arkhipkin 2005). ...
... Similar to Liu et al. (2011), we did not find that Ba/Ca in D. gigas statolith was negatively related to water temperature, whereas this inverse relation was found in the statoliths of L. gahi (Arkhipkin et al. 2004) and Sepia officinalis (Zumholz et al. 2007a ). Previous studies suggested that Ba/Ca in calcified structures of organisms had positive correlations with Ba/Ca in seawaters (Bath et al. 2000; Zacherl et al. 2003) and displayed a nutrient-like distribution with its concentration increasing with depth (Zumholz et al. 2007b ). Thus, Ba was considered as an indicator for the existence of upwelling and vertical movements of squids (Lea et al. 1989; Arkhipkin et al. 2004). ...
We applied the solution-based inductively coupled plasma mass spectrometry to quantify trace elements in statoliths of Humboldt squid, Dosidicus gigas, collected from the high seas off Chile, Peru, and Costa Rica by Chinese squid jigging vessels during 2007–2009. All squid samples were aged and their spawning dates were back-calculated based on daily increments in statoliths. The most abundant trace elements in the whole statolith were Ca and Sr followed by other elements in the order of Fe, Mg, Zn, Ba, Cu, Mn, Ni, Al, Cr, Co, and U. Significant differences in Mn and Sr were found among samples from the three regions. Sr, Ni, Mn, and Co contributed significantly to the discrimination among the regions, with Co responsible for explaining most of the variation, followed by Ni, Mn, and Sr. Squid from the high seas off Costa Rica could be separated from those off Peru and Chile mostly due to the differences in Ni, Sr, and Co, while samples off Peru and Chile could be distinguished mainly because of differences in Mn and Co. Discriminant function analysis suggested that the overall cross-validated classification rate was 85.6 % with samples off Chile having the highest correct identification rates and samples off Costa Rica having the highest false classification rates. Significant positive relationships were found between sea surface temperature (SST) and Cr/Ca, Mn/Ca, and U/Ca, and there was a negative relationship between SST and Cu/Ca, Sr/Ca. This study suggests that the spatial difference in trace elements of statolith can be used to separate geographic populations of D. gigas and that elements having significant relationships with SST can be considered as natural indicators of ambient temperature.
... However, at least for Zn, this protection cannot be supported by our results. Further, there is also evidence that environmental conditions, specifically temperature, can affect Sr contents in statoliths of encapsulated marine neogastropod larvae (Zacherl et al. 2003b). In this context, it would be desirable to analyse the elemental composition of the liquid inside the eggs and the yolk to learn about relations between statolith composition and these factors. ...
... In corals, Ba is therefore used as an indicator for upwelling events (Lea et al. 1989). Experimental data indicate a positive correlation of Ba/Ca in gastropod larvae protoconchs (Zacherl et al. 2003b) and fish otoliths (Bath et al. 2000, Elsdon & Gillanders 2003, Bath-Martin et al. 2004 with Ba/Ca in the seawater. The Ba/Ca distribution found in our study corresponds to the previously stated ontogenetic migrations from surface waters during the juvenile stage to mesobathy-pelagic waters in the subadult and adult stages in Gonatus fabricii (Kristensen, 1984). ...
Statoliths of the gonatid squid Gonatus fabricii from Disko Bay, West Greenland, were analysed by laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS) to determine the concentrations and spatial distributions of 9 minor and trace elements (Sr, Ba, Mg, U, Zn, Mn, Y, Zr, Na). Element composition was assigned in situ to distinct statolith regions, corresponding to ontogenetic stages of an individual squid's life. Significant variations in concentrations of all measured elements except Na were found between different regions of the statolith. Variations in Ba/Ca ratios suggest that juveniles inhabit surface waters, while larger specimens move to deeper waters. U/Ca and Sr/Ca ratios increased towards the outer statolith region, suggesting migration of adult squid into colder waters. Mg/Ca ratios decreased progressively from the core to the edge, most likely related to changes in protein concentrations in their microstructure during ontogenesis. This study is one of the first to apply LA-ICP-MS to cephalopod statoliths. Our results emphasise the strong potential of spatially resolved statolith analyses to gather information on life history, migrations and habitat use of cephalopods.
... Statocysts in mollusks appear as ectodermal intussusceptions, the cavity of which usually closes, although in some cases a canal remains that communicates with the external environment (Markl, 1974). The laying of statoliths in statocysts occurs during the larval development in the egg capsule (Bell, 1982(Bell, , 1983(Bell, , 1984Lloyd et al., 2008;Manríquez et al., 2012;Zacherl et al., 2003Zacherl et al., , 2003a. The statolith nucleus in mollusks, including gastropods, is formed at the early stages of ontogeny, usually endogenously. ...
... However, pre-evaluating the similarity of microchemical characteristics for better selection of sampling sites and design of similar experiments and studies requires the knowledge of environmental conditions and how would those conditions affect the shell generation process of P. canaliculus. Although a range of environmental factors, such as temperature (Zacherl, 2002;Zacherl et al., 2003) and salinity (Beer et al., 2011), have been shown to influence the incorporation of specific trace elements into the shell material of mollusc species, this relationship has not been well described in P. canaliculus and more research is needed to help understand the basis for patterns of misallocation and understand regional gradients in microchemistry to improve future sampling and the application of these shell microchemistry methods. Table 3 Inferred natal sites of newly arrived green-lipped mussel spat in BoP from November 2020-January 2021, based on the site-scale QDA model trained by the shell microchemistry features of larval mussel cultured in situ. ...
... Статоцисты у моллюсков возникают в виде эктодермальных инвагинаций, полость которых обычно закрывается, хотя в некоторых случаях остается канал, сообщающийся с внешней средой (Markl, 1974). Закладка статолитов в статоцистах происходит во время развития личинки в яйцевой капсуле (Bell, 1982(Bell, , 1983(Bell, , 1984Lloyd et al., 2008;Manríquez et al., 2012;Zacherl et al., 2003Zacherl et al., , 2003a. Ядро статолита у моллюсков, в том числе брюхоногих, образуется на ранних стадиях онтогенеза, как правило, эндогенным путем. ...
In various invertebrate groups, the gravity perception organ (statocyst) includes receptor cells and inertial
mass. In gastropods, inertial mass can be represented by both multiple statoconia and single statoliths. Statoliths
are small paired formations which are generally roughly spherical in shape and consist of calcium carbonate
polymorphic modifications (mostly aragonite). The present review examines gastropod statolith ontogeny,
including the early stages of their formation, analyzes the process of statolith growth in different gastropod
species, their structure and morphometric characteristics, features of their internal structure, and the
chemical and mineralogical composition. Different types of emerging concentric marks (growth rings, hatching/
settling rings, rings marking other ontogenetic events) on the statoliths, and the reasons for their formation
are discussed. The advantages of using statoliths as recording structures are considered. Verification data
concerning the formation of annual marks on statoliths are also analyzed.
... temperature (Zacherl et al. 2003). Indeed, the theory has been repeatedly supported by inorganic 510 ...
Quantitative profiles of stable isotopes and trace elements in biogenic carbonates have received considerable attention for the purpose of reconstructing past temperatures. The relationships between temperature and the geochemical parameters of carbonates are often subject to both inter- and intraspecific variations, which critically impair the accuracy of temperature estimation. One of the issues that must be addressed to improve temperature estimation is enhancing our understanding of the influence of the kinetic effect. This effect matters because the purely thermodynamic effect to geochemical profiles cannot be effectively separated from the effect of temperature-driven calcification rate. Cowries (Mollusca, Gastropoda, Cypraeidae) may provide a good model system for quantitatively investigating these two effects, because they undergo a callus-building stage in which aragonitic shell formation exclusively occurs to monotonically increase the thickness outward. We reared a total of 230 juvenile individuals of Monetaria annulus under six constant thermal regimes, ranging from the minimum growing temperature (21°C) to the maximum tolerated long-term temperature (34°C). The portions of the shells built in the callus-building stage were analyzed to quantify isotopic and elemental compositions. Shell growth rate positively depended on temperature from 21°C to 33°C, but dramatically decreased at 34°C, presumably because of high temperature stress. Nevertheless, the heat stress did not make any impact on the thermal dependences (and among-individual variabilities within the same temperature) of either δ¹⁸Oc or Sr/Ca. A linear relationship exists between temperature and the stable oxygen isotope value of the shells (δ¹⁸Oc) across the entire thermal range (n = 103), whereas the shell Sr/Ca ratio increased exponentially with increasing temperature (n = 227). These results strongly suggest that any chemical processes responsible for quantitative incorporation of ¹⁸O and Sr into aragonite crystals were not impacted by heat stress at temperatures up to 34°C. Within-temperature residual correlations between shell growth rates and δ¹⁸Oc were weakly positive, which is compatible with a widely accepted hypothesis that carbonic anhydrase suppresses the kinetic effect in molluscs. Likewise, we found no association between shell growth rates and Sr/Ca, which rejected the possibility that faster CaCO3 precipitation caused the positive relationship between temperature and Sr/Ca. A large proportion of among-individual variability in shell Sr/Ca was caused by unspecified factors other than temperature. This makes it difficult to accurately estimate the past temperature by measuring the Sr/Ca value of a single shell specimen.
... Our results do not support such a relationship, but rather a strong physiological control. The observed relationship between temperature/salinity and Ba deposition in different studies is highly variable, alternatively finding a positive (Carson et al. 2013), negative (Zacherl et al. 2003, Lloyd et al. 2008, Beer et al. 2011 or no relationship (Strasser et al. 2008, Carson et al. 2013, Kroll et al. 2016, and reinforcing the presence of extensive physiological control on biocarbonate deposition. Regarding our results, no significant relationship with temperature or salinity was detected (Tables 4 & 5), but the small number of samples above the detection limit lowered the power of our analysis and restrained the interpretation of the effects of those factors on the incorporation of Ba. ...
... Field validation can include indirect and direct larval tracking efforts. Indirect tracking has been attempted using genetics (Gilg and Hillbish 2003;Taylor and Hellberg 2003;Galindo et al. 2010) and chemical tracers such as trace elements (DiBacco and Levin 2000;Zacherl et al. 2003;Becker et al. 2007;Kroll et al. 2016). These approaches have significant uncertainty among locations (Thorrold et al. 2002), making interpretation of larval dispersal difficult. ...
Knowledge of larval transport is important for restoration and management efforts; yet, there are no established methods to determine larval transport in situ. Calcein staining of oyster larvae may help fill this void, and a two-part study was conducted to determine its effectiveness at tracking larval oyster transport in the field. First, it was tested whether oysters could be successfully stained, survive, and grow at estuarine salinities (15, 20, 26), and at sufficiently large numbers (millions of oysters) to support field mark-recapture studies. Second, the field-based application was tested by releasing 22 million stained larvae twice (high and low salinity) into a major estuary, and two methods (fluorescent microscopy and FlowCam) were used to detect recaptured larvae. Results were compared with expected larval movement patterns simulated by an existing larval transport model. Calcein concentrations (100 mg L⁻¹) did not affect larval growth or survival, but handling conditions (water salinity manipulations and tank size) did affect growth and survival during the post-staining period. Microscopy had double the detection capacity, but FlowCam was more practical and time efficient for the large-volume, high particulate load field samples. Larvae (n = 2) were recaptured during the second, higher salinity release, and model comparison showed a 1–2-day time-lag between field recapture and model predictions, suggesting need for model refinement. Calcein has potential to be a useful marker to track larval movement at large scales needed for field-based studies, providing critical information to aid in selection of restoration sites and management of commercially important shellfish species.
... Elemental fingerprinting requires that sufficient chemical variability of the water be present over space, but also that the chemistry of the calcified structures in some way reflects the physicochemical properties of the water. Controlled laboratory experiments indicate linear relationships between the concentrations of several elements in seawater and in calcified structures (mollusc larval shells and statoliths 96,97 , but also interactive effects of temperature and salinity (fish otoliths 98 ; mollusc larval shells Andreia Carvalho & Laura Peteiro, unpublished data) that will influence the multivariate distribution of elements in the target structure and may complicate the probabilistic assignment of individuals and the interpretation of the patterns. The biophysical model on the other hand is constrained by its internal variability and may not be resolving appropriately all details of the oceanography and biology. ...
Marine larval dispersal is a complex biophysical process that depends on the effects of species biology and oceanography, leading to logistical difficulties in estimating connectivity among populations of marine animals with biphasic life cycles. To address this challenge, the application of multiple methodological approaches has been advocated, in order to increase confidence in estimates of population connectivity. However, studies seldom account for sources of uncertainty associated with each method, which undermines a direct comparative approach. In the present study we explicitly account for the statistical uncertainty in observed connectivity matrices derived from elemental chemistry of larval mussel shells, and compare these to predictions from a biophysical model of dispersal. To do this we manipulate the observed connectivity matrix by applying different confidence levels to the assignment of recruits to source populations, while concurrently modelling the intrinsic misclassification rate of larvae to known sources. We demonstrate that the correlation between the observed and modelled matrices increases as the number of observed recruits classified as unknowns approximates the observed larval misclassification rate. Using this approach, we show that unprecedented levels of concordance in connectivity estimates (r = 0.96) can be achieved, and at spatial scales (20-40 km) that are ecologically relevant.
... Galante-Oliveira et al. (2015) reported periodic changes in the Sr/Ca ratio of statoliths from, the gastropod N. reticulatus with maximum concentrations coinciding with winter deposited statolith growth rings in 92% of cases (n = 20), suggesting an inverse relationship with seawater temperature. Similarly, Zacherl et al. (2003) also reported an inverse correlation between Sr and seawater temperature in the larval statoliths of the marine gastropod Kelletia kelletii. However, such relationships were not found in the pre-hatching (larval) area of the statoliths of B. undatum, and no clear periodic cycles in the Sr/Ca ratio profiles were seen. ...
The whelk Buccinum undatum is commercially important in the North Atlantic. However, monitoring the ontogenetic age and growth of populations has been problematic for fisheries scientists owing to the lack of a robust age determination method. We confirmed the annual periodicity of growth rings present in calcified statoliths located in the foot of field-collected and laboratory reared whelks using microscale measurements of trace element geochemistry. Using Secondary Ion Mass Spectrometry (SIMS), annual trace element profiles were quantified at 2μm resolution in statoliths removed from whelks collected alive from three locations spanning the length of the UK; the Shetland Isles (North), the Menai Strait, North Wales (Mid) and Jersey (South). Clear cycles in the Mg/Ca ratio were apparent with minimum values corresponding with the visible dark statolith rings and comparatively higher ratios displayed in the first year of growth. Statoliths from one and two-year-old laboratory reared whelks of known age and life history contained one and two Mg/Ca cycles respectively and demonstrated that the statolith growth ring is formed during winter (February and March). Cycles of Na/Ca were found to be anti-correlated to Mg/Ca cycles, whilst ratios of Sr/Ca were inconsistent and showed an apparent ontogenetic increase, suggesting strong physiological control. Variability in elemental data will likely limit the usefulness of these structures as environmental recorders. The results obtained using SIMS for trace element analysis of statoliths confirms the robustness of the statolith rings in estimating whelk age. μXRD at 2μm spatial resolution demonstrated the statoliths were wholly aragonitic and thus trace element variation was not the result of possible differences in CaCO3 polymorph within the statolith. Changing XRD patterns along with SEM imaging also reveal an 'hourglass' microstructure within each statolith. The validation of the annual periodicity of statolith growth rings now provides a robust and novel age determination technique that will lead to improved management of B. undatum stocks.
... The majority of freshwater input is from the Hā tea River, located in the upper reaches of the harbour, which has a mean flow of 10 m 3 s −1 (Inglis et al. 2006). Whangarei Harbour supports a significant commercial, recreational and traditional fishery of A. stutchburyi, with commercial efforts restricted to Snake Bank (Williams et al. 2006). There has been interest in the restoration of historically important A. stutchburyi populations in recent years (Cummings et al. 2007, Lundquist et al. 2009, Hewitt & Cummings 2013). ...
Trace elemental fingerprinting has been used to estimate population connectivity o marine species by using variations in the chemistry of shell produced in different water masses t determine the natal location of settlers. This method has been successfully used to differentiat between estuaries and coasts at spatial scales of 10s to 100s of km. Here, we investigated the suitabilit of trace elemental fingerprinting to distinguish subpopulation connectivity at managemen scales suitable for local fishery or conservation management. The trace element chemistry o Austrovenus stutchburyi shells was used to distinguish between intra-And inter-estuary sub populations at local (∼1 to 10 km) scales, with ∼99% success. Differences between 8 location within a large harbour and 4 smaller neighbouring estuaries were detected. Sr:Ca, Zn:Ca an Mn:Ca elemental ratios were the primary drivers of inter-site trace elemental fingerprint differences Intra-shell variation in elemental fingerprints was used to examine temporal stability an demonstrated that, although intra-shell differences were present, site-specific differences in elementa fingerprints were maintained. The results of this study suggest trace elemental fingerprintin can be a viable method to estimate population connectivity over small inter-And intra-estuar spatial scales.
... Dosidicus gigas has a typical cephalopod statolith structure, composed of nucleus, postnuclear zone, dark zone, and peripheral zone, representing the embryonic, paralarval, juvenile, and adult phase, respectively [42]. The difference in the micro-chemical composition of different The uptake and deposition of elemental signatures in hard structures are a response to the properties of water masses, of which temperature is the most important, which has resulted in these elemental signatures to be considered useful indicators for marine animals [43][44][45][46]. Sr is a key element in the elemental signature deposition of cephalopod statoliths [36,47]), and its concentration has an evident relationship with surrounding temperature. ...
Cephalopods exhibit a variety of movement patterns during their lifespan, from the passive drifting of eggs and paralarvae to the active long-distance migrations of adults between feeding and spawning grounds. However, it is difficult to observe directly the movements of cephalopods at these different stages of development. An alternative approach is the use of elemental signatures recorded in statoliths to gain valuable insight into cephalopod movement. Dosidicus gigas is an economically important squid that undertakes large-scale migrations over its lifespan to satisfy its habitat requirements at different life history stages. In this study we used D. gigas as an example to illustrate a new approach to reconstructing cephalopod migration patterns using the relationship between sea surface temperature and elemental signature analyses of statoliths. We found that statolith elemental signatures are a useful natural tag to ascertain D. gigas migration routes from juvenile to adult stages. This approach is not applicable to embryonic and paralarval stages during which movement is more likely passive and determined by ocean currents. The conclusions which can be drawn from this study improve our knowledge of the distribution and migration of juvenile and adult cephalopods. Supplementary trophic analyses using stable isotopes would further benefit the reconstruction of cephalopod migration pathways.
... Our results are consistent with previous research indicating that species-specific temperature effects can influence partition coefficients for metals such as Ba and Mg, confirming the need for validation studies prior to interpreting values in wild-caught fish (Elsdon & Gillanders 2002, Bath Martin et al. 2004, Miller 2009, 2011. Our observation that there was no temperature effect on D Sr for either species contrasts with the behavior of the Sr/Ca ratio in biogenic aragonite in different taxa observed by others (Shen et al. 1996, Elsdon & Gillanders 2002, Zacherl et al. 2003, Bath Martin et al. 2004), which may be explained by the magnitude and relatively narrow temperature range tested in our study. These differences highlight a need for more investigation into the biological control over Sr incorporation that is exerted by different kinds of organisms. ...
Characterizing the behavior of larvae prior to settlement is integral to understanding population dynamics because coastal oceanography may facilitate or limit settlement. Otolith microchemistry can be used to determine patterns of fish movement, although there is a limited understanding of how this tool can be applied in coastal marine systems. Our goal in this study was to evaluate the application of otolith microchemistry to characterize water mass associations of settlement-stage marine fish in a coastal upwelling region using a 3-step approach. First, we characterized seawater chemistry of coastal water mass types across multiple years, finding differences in the chemical signatures of strong upwelling, weak upwelling, and relaxation events. Second, we experimentally determined the effect of temperature on the partitioning of trace elements in otoliths for 2 rockfishes (Sebastes spp.) to find that the effect of temperature on otolith partition coefficients was element-and species-specific. Finally, we compared coeval changes in seawater and otolith chemistry of settlement-stage rockfishes that were exposed to naturally variable conditions over an upwelling-relaxation cycle. We subsequently evaluate whether laser ablation inductively coupled plasma mass spectrometry effectively measures otolith chemistry over ecologically relevant time scales. We discovered that elemental concentrations in otoliths respond rapidly to changes in seawater chemistry and reflect equivalent proportional changes. This study provides evidence that elemental signatures are valuable tools for reconstructing larval histories of marine fish in coastal upwelling regions.
... Variability of Sr/Ca in coral Montastraea annularis skeleton depends strongly on SST (Swart et al., 2002). Zacherl et al. (2003) showed a significant inverse effect of temperature on Sr incorporated into neogastropod Kelletia kelletti. However, temperature reconstruction based on Sr/Ca in otolith is complicated and only performed well for fishes in cold waters (Campana, 1999). ...
We applied solution-based ICP-MS method to quantify the trace-elemental signatures in statoliths of jumbo flying squid, Dosidius gigas, which were collected from the waters off northern and central Chile during the scientific surveys carried out by Chinese squid jigging vessels in 2007 and 2008. The age and spawning date of the squid were back-calculated based on daily increments in statoliths. Eight elemental ratios (Sr/Ca, Ba/Ca, Mg/Ca, Mn/Ca, Na/Ca, Fe/Ca, Cu/Ca and Zn/Ca) were analyzed. It was found that Sr is the second most abundant element next to Ca, followed by Na, Fe, Mg, Zn, Cu, Ba and Mn. There was no significant relationship between element/Ca and sea surface temperature (SST) and sea surface salinity (SSS), although weak negative or positive tendency was found. MANOVA analysis showed that multivariate elemental signatures did not differ among the cohorts spawned in spring, autumn and winter, and no significant difference was found between the northern and central sampling locations. Classification results showed that all individuals of each spawned cohorts were correctly classified. This study demonstrates that the elemental signatures in D. gigas statoliths are potentially a useful tool to improve our understanding of its population structure and habitat environment. © 2015, Science Press, Ocean University of China and Springer-Verlag Berlin Heidelberg.
... Our laboratory experiments exhibited no significant correlations between ambient Ba concentration and temperature and/or salinity. In the field, however, higher levels of Ba were detected at lower temperatures, a trend also found in clams (Strasser et al. 2008b) and neogastropod shells (Zacherl et al. 2003). There was an anomalous spike in Ba at higher temperatures (> 26°C) within the HT site; however, this site also experienced the greatest variance in Ba concentrations (Fig. 3b). ...
We evaluated the utility of geochemical tagging methods to discern larval connectivity among an invertebrate metapopulation within a large (∼5000 km2) temperate estuary. Specifically, we examined how estuarine-scale gradients in temperatures (21° to 26.5°C), salinities (12.5 to 20 ppt), and trace metal concentrations (ambient, +16 ppb Mn and 0.16 ppb Pb, or +32 ppb Mn and 0.32 ppb Pb) affect Crassostrea virginica larval-shell signatures of Mn, Sr, Ba, and Pb in controlled mesocosms. We also utilized field-collected, newly settled oysters across Pamlico Sound, NC, USA, to explore signature variability among natural temperature and salinity gradients and examine the spatial resolution at which geochemical signatures can be used to discriminate between collection regions. Mesocosm experiments revealed environmentally and statistically significant interactive effects between temperature and salinity on elemental ratios in larval oyster shells, favoring higher Sr concentrations in cooler, fresher water, but no effects of these factors on Ba signatures. Mesocosm trials also showed increased Mn signatures in larval shell following from spiking mesocosms with Mn solutions; however, this relationship did not hold for Pb following analogous elemental spikes. Our field collections of recent settlers showed similar patterns of high Sr at relatively low salinities and temperatures, without clear environmental gradients for Ba. Overall, we found that across regional (35 km) spatial scales, environmental variables, such as salinity and temperature, can generate distinct multi-elemental signatures between putative natal sites. However, if sites are close together or located in similar environments, discrimination among sites appears greatly reduced. We suggest that geochemical tagging provides a promising approach for characterizing larval connectivity among subpopulations within whole-estuarine systems.
... Water temperature can influence Sr concentrations in teleosts; however, both positive and negative correlations with Sr concentration are reported (Arkhipkin et al. 2004a;Elsdon and Gillanders 2003;Ikeda et al. 2002;Yatsu et al. 1998). Barium concentrations in both otoliths and statoliths are reflective of oceanographic nutrient concentration and water temperature (Hamer et al. 2006;Zacherl et al. 2003;Zumholz et al. 2007a) and are normally related to upwelling or differences between surface and bottom waters where concentrations increase with depth (Boyle 1988;Lea et al. 1989;Woodson et al. 2013). However, the contribution of seasonal upwelling that occurs off the Bonney coastline of Victoria and South Australia during February may complicate interpretation (Schahinger 1987). ...
While arrow squid (Nototodarus gouldi) in Australia are currently managed as a single population, biological differences in individuals between locations of capture suggests these are separate stocks requiring stock-specific harvest strategies. We used two techniques to derive information about stock structure from different parts of the life cycle, providing a novel holistic approach to exploring stock structure. This study combined two techniques, statolith shape and statolith elemental composition, to determine dispersal patterns of N.gouldi between regions and evidence of separate stocks. While adult statolith shape provided evidence that adults caught in the two locations belonged to different stocks, statolith elemental composition suggested that N.gouldi caught at each location had hatched throughout their distribution, with egg mass and juvenile drift potentially facilitated by seasonal longitudinal ocean currents. However, there was evidence of asymmetry in ontogenetic movement of N.gouldi, with adults in Victoria contributing more to the Great Australian Bight stock than vice versa and with the implication that the Victorian stock may need to be managed as the source stock.
... Water temperature can influence Sr concentrations in teleosts; however, both positive and negative correlations with Sr concentration are reported (Arkhipkin et al. 2004a;Elsdon and Gillanders 2003;Ikeda et al. 2002;Yatsu et al. 1998). Barium concentrations in both otoliths and statoliths are reflective of oceanographic nutrient concentration and water temperature (Hamer et al. 2006;Zacherl et al. 2003;Zumholz et al. 2007a) and are normally related to upwelling or differences between surface and bottom waters where concentrations increase with depth (Boyle 1988;Lea et al. 1989;Woodson et al. 2013). However, the contribution of seasonal upwelling that occurs off the Bonney coastline of Victoria and South Australia during February may complicate interpretation (Schahinger 1987). ...
Arrow squid, Nototodarus gouldi, are managed as a single population in Australia;
however, it is unknown whether N. gouldi caught in Victoria and the Great Australian
Bight are from separate stocks. This study examines whether N. gouldi caught in these
two spatially separated locations of southern Australia are different stocks. Fourier shape
analysis of statoliths was used to determine whether discrete phenotypic stocks exist;
whereas statolith element concentrations were used to determine where individuals
from both locations are likely to have hatched. Comparing statolith shape from squid
collected in Victoria to squid collected in the Great Australian Bight suggested significant
phenotypic heterogeneity in stocks; whereas statolith elemental composition analysis
suggests that N. gouldi caught at either location hatched throughout their distribution.
Although N. gouldi caught in the Great Australia Bight and Victoria appeared to be
separate stocks, squid from both regions are important for recruitment.
... There are only a few studies on trace element incorporation into the larval shells of marine molluscs. Sr incorporation was shown to increase with temperature in the protoconch of the gastropod Kelletia kelleti (Zacherl et al. 2003). The results suggested the use of protoconch shell as proxies for environmental reconstructions, but the relationship 1 3 between trace element composition and shell microstructure was not investigated. ...
The shell of the European abalone Haliotis tuberculata is a model for studying mechanisms of mollusc shell formation, but the early steps of shell formation and calcification remain poorly documented. The microstructure and the mineralogical and geochemical composition of larval and juvenile shells were investigated by scanning electron microscopy, infrared spectroscopy and ion microprobe analyses (NanoSIMS). Analyses were performed on shells obtained from controlled fertilisations at the hatchery France-Haliotis (Plouguerneau, France) in July 2009 and 2010 using abalone from Roscoff. Shell cross sections revealed the microstructural arrangement of the developing shell, showing progressive biomineral organisation into two differentiated layers, i.e. the outer granular and the internal nacreous layer. Infrared analysis confirmed that the European abalone shell, at every stage of development, was mostly composed of CaCO3 in the form of aragonite. Variations in trace element composition, i.e. Sr/Ca, were measured in the different stages and correlated with micro-structural changes in the shells. Experimental manganese labelling of live abalones produced cathodoluminescence marks in the growing shell sections. The increase in shell thickness can be used to determine the growth rate of an early adult abalone shell.
... and so on (Campana and Neilson, 1985;Song et al., 2006). The relationship between the chemical composition in the zoning structure of otoliths and ambient environmental factors such as elemental composition, temperature and salinity were studied (Campana, 1999, Thorrold et al., 1997Elsdon and Bronwyn, 2002;Zacherl and Georges, 2003;Martin and Thorrold, 2004). Recently, some authors have tried to demonstrate that otoliths are a potential proxy for monitoring changes in water quality (Yang et al., 2006;Li et al., 2008;Gao et al., 2008;Luo et al., 2008;Yan et al., 2008). ...
Otolith is a typical biomineral carrier growing on insides of fish skull with prominent zoning structure formed by alternating layers of protein and calcium carbonate around the nucleus. The zoning number and the thickness of the rhythmic zone can reflect the age and the growing velocity. The δ 18 O values of the calcium carbonate are indicators of the temperature of the water where the fish lives. The geometry, color, common and trace elements, oxygen and carbon isotopes of the zones can be employed effectively to classify the species, trace the source, migration habits, nutrition level of the fish and the variation of the ocean environment, in order to predict the environmental variation trend of related waters and make strategic plan for fishery production. Thermoluminescence technique can be taken as a new tool in the investigation of fish otolith to describe the heavy metal pollution of related waters, and the thermoluminescence parameters can be used to deduce the source and manage fishery resources.
... Barium concentrations in statoliths are useful in understanding migration and natal origin; however, interpretation can be difficult as localised environmental conditions can be very dynamic compared to other regions. Barium concentrations in both otoliths and statoliths are reflective of oceanographic nutrient concentration and water temperature (Zacherl et al., 2003b;Fowler et al., 2005;Warner et al., 2005;Hamer et al., 2006;Zumholz et al., 2007a). In ocean systems, these parameters are normally related to upwelling or differences between surface and bottom waters where concentrations increase with depth (Boyle, 1988;Lea et al., 1989). ...
... Although, Co and Ni were significantly higher in males suggesting that There have been relatively few studies on the direct causal and regulatory mechanisms that govern the incorporation of elements into biomineralised structures. Barium (Zacherl et al. 2003) and Sr (Elsdon & Gillanders 2004) concentration in gastropod statoliths and fish otoliths respectively have been directly associated with seawater concentration, and temperature has shown to negatively correlate with Sr concentration in squid statoliths ) and octopus statoliths (Ikeda et al. 1999). Food is likely to be an important source of element uptake for cephalopods, due to their rapid growth rate, high metabolism and food intake requirements (Bustamante et al. 2004), with diet found to significantly influence Ba concentrations in cuttlefish statoliths (Zumholz et al. 2006). ...
... In addition to the Ba concentration in seawater, temperature can also influence Ba/Ca values in coral aragonite; dissolved Ba 2+ can be incorporated within coral aragonite in solid solution. The temperature dependency of the distribution coefficient of Ba (D Ba ) between seawater and aragonite has been studied, defined as D Ba = (Ba/Ca) aragonite /(Ba/Ca) seawater (Zacherl et al., 2003;Dietzel et al., 2004). Assuming the relationship between D Ba (Dietzel et al., 2004) and SST observed at Khang Khao (27.1-30.0°C) ...
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used to assess the impact of metal pollution on Porites skeletons taken from the Gulf of Thailand since the 1980s. The collection period coincided with a series of laws enacted by the Thai government to curb environmental pollution. The extent of metal pollution by riverine input, including aerosol deposits, was assessed by comparing the metal/Ca (Me/Ca) ratios in the Thai corals to the ratios of another colony of corals sampled from Rukan-sho, a relatively unpolluted coral reef located in Okinawa, Japan. In this comparison, high riverine inputs of Ba, V, Cd and Pb were observed in the Thai coral samples. Higher V/Ca ratios found in the Thai corals compared to the Rukan-sho coral suggest anthropogenic V inputs due to fuel oil pollution in the Gulf since the late 1990s. The levels of Cd in the coral suggest a gradual decrease in the Gulf in the late 1990s, with a drastic drop in concentration from the 1980s. The historical variation in Pb/Ca ratios recorded in the coral skeletons suggests that exposure to anthropogenic Pb was a result of discharge from urbanized areas from 1984 to 1998, which has been gradually reduced since Thailand prohibited the use of leaded gasoline in the late 1990s.
... Trace element compositions of carbonate precipitates such as speleothem (Fairchild et al., 2000), biogenic skeletons of foraminifera (Elderfield and Ganssen, 2000), coccolith (Rickaby et al., 2007), coral (Mitsuguchi et al., 1996), ostracod (Wansard et al., 1998) and gastropod (Zacherl et al., 2003) have been successfully applied to paleo-reconstruction. However, information on the incorporation of trace elements into the authigenic carbonates in soil is rare although soil carbonates may record the condition under which they are precipitated (e.g., Breecker et al., 2009;Cerling, 1984). ...
... The strong, negative effect of temperature on Ba incorporation in U. halleri is similar to the pattern observed by Balter & Lécuyer [93] in laboratory studies of synthetic hydroxyapatite. Decreases in Ba/Ca ratios with increasing ambient water temperature have also been found in laboratory studies with synthetic aragonite [67], cephalopods [38], larval gastropods [91,94], juvenile clams [95], and larval fish [42]. However, positive or no effect of temperature on Ba incorporation into otoliths has been much more commonly observed [40]. ...
Differences in the chemical composition of calcified skeletal structures (e.g. shells, otoliths) have proven useful for reconstructing the environmental history of many marine species. However, the extent to which ambient environmental conditions can be inferred from the elemental signatures within the vertebrae of elasmobranchs (sharks, skates, rays) has not been evaluated. To assess the relationship between water and vertebral elemental composition, we conducted two laboratory studies using round stingrays, Urobatis halleri, as a model species. First, we examined the effects of temperature (16°, 18°, 24°C) on vertebral elemental incorporation (Li/Ca, Mg/Ca, Mn/Ca, Zn/Ca, Sr/Ca, Ba/Ca). Second, we tested the relationship between water and subsequent vertebral elemental composition by manipulating dissolved barium concentrations (1x, 3x, 6x). We also evaluated the influence of natural variation in growth rate on elemental incorporation for both experiments. Finally, we examined the accuracy of classifying individuals to known environmental histories (temperature and barium treatments) using vertebral elemental composition. Temperature had strong, negative effects on the uptake of magnesium (DMg) and barium (DBa) and positively influenced manganese (DMn) incorporation. Temperature-dependent responses were not observed for lithium and strontium. Vertebral Ba/Ca was positively correlated with ambient Ba/Ca. Partition coefficients (DBa) revealed increased discrimination of barium in response to increased dissolved barium concentrations. There were no significant relationships between elemental incorporation and somatic growth or vertebral precipitation rates for any elements except Zn. Relationships between somatic growth rate and DZn were, however, inconsistent and inconclusive. Variation in the vertebral elemental signatures of U. halleri reliably distinguished individual rays from each treatment based on temperature (85%) and Ba exposure (96%) history. These results support the assumption that vertebral elemental composition reflects the environmental conditions during deposition and validates the use of vertebral elemental signatures as natural markers in an elasmobranch. Vertebral elemental analysis is a promising tool for the study of elasmobranch population structure, movement, and habitat use.
... Arkhipkin et al. (2004) suggested that intensification of upwelling is responsible for the elevated levels of Ba in L. gahi statoliths collected from shelf waters around the Falkland Islands. Positive correlations of Ba:Ca in gastropod larval protoconchs (Zacherl et al. 2003b) and fish otoliths (Bath et al. 2000) with Ba:Ca in the seawater were identified. Alternatively, Ba:Ca was considered a useful indicator for vertical movements of cephalopods (Arkhipkin et al. 2004). ...
Ontogenetic variation in 4 trace element ((88)Sr, (137)Ba, (24)Mg, (23)Na) concentrations and their ratios to Ca were measured in statoliths of the jumbo flying squid Dosidicus gigas off the Exclusive Economic Zone of Chilean and Peruvian waters using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The element compositions of statoliths showed no significant differences between females and males. All of the elements in different growth zones showed significant variations, except for Mg. Sr:Ca and Mg:Ca were good indicators for distinguishing squid from autumn and winter spawning seasons. Sr:Ca and Ba:Ca distribution patterns in statoliths confirmed that paralarvae and juvenile squid inhabit surface waters, while subadult squid migrate into deeper waters. An increasing Sr: Ca ratio of subadult squid could be explained by declining temperature gradients from northern to southern sampling locations, although no significant Sr: Ca differences were observed (p > 0.05). Mg:Ca ratios decreased progressively from the nucleus to the peripheral zone, which might be correlated with statolith growth rates. Na:Ca ratios slightly declined from paralarvae to the subadult phase. Quantitative relationships between statolith trace elements and environmental conditions under different growth stages are needed to improve our understanding of life history of D. gigas.
... Otoliths were removed and prepared according to the methods of Michel et al. (2008). Ratios of Sr:Ca and Ba:Ca were measured in the core and edge of each otolith by laser ablation inductively-coupled plasma mass spectrometry (LA-ICPMS, New Wave UP 213 laser ablation system and Perkin Elmer Elan SCIEX DRCII ICPMS) using helium/argon carrier gas to enhance sensitivity through increased production and transfer of ablated particles to the ICPMS (Swearer 2000;Zacherl et al. 2003). Otoliths were placed in the sample cell and the central nucleus and edge were located for spot analysis at 400× magnification with a video imaging system. ...
Previous research has identified distinct genetic, life‐history and reproductive differences between populationsof common bully (Gobiomorphus cotidianus) upstream and downstream of a pulp and paper mill outfall on the Tarawera River in the Bay of Plenty, New Zealand. This study investigated the distribution of common bully in the Tarawera River by examining fish collected from upstream (37 km inland) and downstream (20 km inland) locations and comparing them to fish from similar inland locations (40 km and 17 km inland, respectively) in the nearby Rangitaiki River. Reproductive divergence was observed between upstream and downstream sites of both rivers by differing annual trends in gonadosomatic index. Stable carbon and nitrogen isotopes confirmed residency at each sampling site and otolith microchemistry demonstrated different life‐history strategies between upstream and downstream populations. Diadromous recruits dominated in both downstream river populations, with a general disappearance of diadromy upstream. A mixture of diadromous and non‐diadromous fish were found in the upstream Rangitaiki River, whereas diadromous recruits were absent in the upstream Tarawera River. A reduction in oculoscapular canal structures also coincided with loss of diadromy in fish from both rivers. A behavioural study to determine whether pulp and paper mill effluent may deter fish migration within the Tarawera River demonstrated a strong avoidance of effluent, but only at concentrations (>25%) greater than those that naturally occur in the river (
... Water and carbonate Sr:Ca and Ba:Ca were positively correlated in juvenile Chinook salmon as previously demonstrated in otoliths of freshwater (Collingsworth et al., 2010;Gibson-Reinemer et al., 2009;Wells et al., 2003), euryhaline (Bath et al., 2000;Elsdon and Gillanders 2003;Martin et al., 2004), and marine (Miller, 2009) fishes as well as foraminifera (Lea and Spero, 1992), bivalves (Gillikin et al., 2006;Lorens and Bender, 1980), and gastropods (Zacherl et al., 2003). In this study, temperature and salinity displayed significant interactive effects on the incorporation of Sr and Ba. ...
... Otolith chemistry can be used to investigate larval dispersal by examining the chemical composition of natal otoliths over different spatial scales. We expected the strong regional differences in temperature and productivity in Galápagos to result in regional differences in natal otolith chemistry, because differences in temperature often result in differences in the chemical composition of otoliths and statoliths (Bath et al. 2000, Zacherl et al. 2003, Martin & Thorrold 2005. However, while there were no differences in natal otolith chemistry among regions for any element, a few elements varied significantly among islands within regions, and all elements showed significant variation among clutches within sites (Table 4). ...
Over the past decade, researchers have used variation in the chemical composition of fish otoliths (earstones) to address a number of ecological questions, such as stock assessment and assessing rates of movement of individuals among habitats or life-history stages. However, these methods have yet to be applied successfully to the study of larval connectivity, a major unanswered question in marine ecology. Accomplishing this task requires a reference collection of pre-pelagic natal otoliths and accurate measurement of the chemical signatures of otoliths cores of recruits. We analyzed the chemical composition of natal otoliths from near-term benthic eggs of a damselfish (Stegastes beebei) from all regions of the Galdpagos Archipelago. There was no consistent variation in chemical signature at the largest scale, among regions in the archipelago (separated by similar to 100 to 150 km). However, we found significant variation among islands within each region (10s of km), and among clutches within islands. In addition, we found that otolith cores of newly settled recruits often differed chemically from natal otoliths (which ultimately make up the otolith core as the fish grows). Variation at smaller spatial scales but not larger ones implies that otolith chemistry will only be usable if larvae disperse short distances in this system, and additional work is required to understand the relationship between the chemistry of natal otoliths and recruit cores. Otolith chemistry has the potential to address questions of connectivity, but our data suggest that these methods should be applied cautiously.
... [21] It is becoming increasingly clear that many proposed proxies in biogenic carbonates are complicated by the influence of the physiology of the animal precipitating the carbonate [e.g., Klein et al., 1996;Stecher et al., 1996;Purton et al., 1999;Vander Putten et al., 2000;Zacherl et al., 2003;Lorrain et al., 2004a]. However, an animal's physiology is often strongly dependent on the environmental conditions it experiences (see section 1). ...
Elemental ratios in biogenic marine calcium carbonates are widely used in geobiology, environmental science, and paleoenvironmental reconstructions. It is generally accepted that the elemental abundance of biogenic marine carbonates reflects a combination of the abundance of that ion in seawater, the physical properties of seawater, the mineralogy of the biomineral, and the pathways and mechanisms of biomineralization. Here we report measurements of a suite of nine elemental ratios (Li/Ca, B/Ca, Na/Ca, Mg/Ca, Zn/Ca, Sr/Ca, Cd/Ca, Ba/Ca, and U/Ca) in 18 species of benthic marine invertebrates spanning a range of biogenic carbonate polymorph mineralogies (low-Mg calcite, high-Mg calcite, aragonite, mixed mineralogy) and of phyla (including Mollusca, Echinodermata, Arthropoda, Annelida, Cnidaria, Chlorophyta, and Rhodophyta) cultured at a single temperature (25°C) and a range of pCO2 treatments (ca. 409, 606, 903, and 2856 ppm). This dataset was used to explore various controls over elemental partitioning in biogenic marine carbonates, including species-level and biomineralization-pathway-level controls, the influence of internal pH regulation compared to external pH changes, and biocalcification responses to changes in seawater carbonate chemistry. The dataset also enables exploration of broad scale phylogenetic patterns of elemental partitioning across calcifying species, exhibiting high phylogenetic signals estimated from both uni- and multivariate analyses of the elemental ratio data (univariate: λ = 0–0.889; multivariate: λ = 0.895–0.99). Comparing partial R² values returned from non-phylogenetic and phylogenetic regression analyses echo the importance of and show that phylogeny explains the elemental ratio data 1.4–59 times better than mineralogy in five out of nine of the elements analyzed. Therefore, the strong associations between biomineral elemental chemistry and species relatedness suggests mechanistic controls over element incorporation rooted in the evolution of biomineralization mechanisms.
In this study, the concentrations of 12 metals: Ca, Na, Sr, Mg, Ba, Mn, Cu, Pb, V, Y, U and Cd in shells of bivalve molluscs (aragonitic: Cerastoderma glaucum, Mya arenaria and Limecola balthica and bimineralic: Mytilus trossulus) and arthropods (calcitic: Amphibalanus improvisus) were obtained. The main goal was to determine the incorporation patterns of shells built with different calcium carbonate polymorphs. The role of potential biological control on the shell chemistry was assessed by comparing the concentrations of trace elements between younger and older individuals (different size classes). The potential impact of environmental factors on the observed elemental concentrations in the studied shells is discussed. Specimens were collected from brackish waters of the Baltic Sea (the Gulf of Gdansk). For every species, 40 individuals (ten in each size class) were selected. Pre-cleaned shells were analysed by ICP-OES and ICP-MS to determine the concentrations of metals.
The distributions of elements both differ between species and exhibit high intraspecific variability. Calcitic shells preferentially incorporated Mg > Sr > Na, aragonitic shells incorporated Na > Sr > Mg, and bimineralic shells accumulated Na approximately two times more intensively, than Mg and Sr which remained at similar levels. Among all species, the calcitic shells of A. improvisus most effectively concentrated the majority of the studied elements, especially Mg > Mn > Ba, which was contrary to the shells of aragonitic molluscs that contained the lowest levels of trace elements. The size-dependent distributions of elements in shells did not exhibit a consistent pattern. The highest significant differences were found for the bimineralic shells of M. trossulus, while the smallest were found for aragonitic shells; if any variability occurred, it was observed in heavy metals (Pb, Cd).
Our results indicate that elemental variability, especially that of Mg and Sr, is dominated by the properties of the crystal lattice. The inconsistent variability of trace element concentrations between species and within single populations supports the important role of species-specific biological control of the biomineralization process and indicates that environmental factors have a significant influence on the incorporation of trace elements into the shells.
The potential of trace and minor elements within biominerals to track the larval dispersal of bivalves was investigated by examining elemental composition in early larval shell of the northern quahog (hard clam) Mercenaria mercenaria. Larvae were cultured in three shellfish hatcheries using the adjacent estuarine waters of the southern Delmarva Peninsula in Virginia. Spatial distinction (similar to 1-50 km) and temporal stability (triweekly) of elemental concentrations was assessed using inductively coupled plasma mass spectrometry. Seventeen minor and trace elements were present at detectable levels in all shell samples: Ca, Mg, Ti, Co, Ni, Zn, Se, Rb, Al, V, Cr, Mn, Cu, Sr, Ba, Pb, and U. Discriminant function analyses using metal-to-Ca ratios as independent variables assigned hard clams to their hatchery of origin correctly, with 100% success. The ratio Cr: Ca proved to be the most effective discriminator, explaining 78.1% of among-group variance. Elemental concentrations within early larval shell also differed temporally. Discriminant function analysis classified individual spawning events with 100% success, with Al: Ca explaining the bulk of among-group variance (81.4%). Despite temporal variability of elements within larval shell, it was possible to resolve elemental signals spatially among hatcheries regardless of spawning date. These results demonstrate for the first time that the chemical composition of hard clam larval shell records spatial elemental signatures with the potential to trace the environment of natal origin as well as subsequent dispersal trajectories of this economically important species.
Spawning aggregations of market squid can cover the benthos with “beds” of capsules. Increased upwelling, ENSO frequency, and other environmental conditions associated with climate change sometimes work together to shoal oxygen minimum zone waters to depths < 90 m, exposing embryos to low levels of dissolved oxygen (DO) and pH. We hypothesized that low DO (90 µmol/kg) and pH (7.5) levels affect squid embryonic development. In the laboratory, squid embryos were initially exposed to two treatments at a constant temperature (11 °C): one with low levels of DO and pH (90 µmol/kg, pH=7.5) and the other with “normal” levels (i.e. DO=240 µmol/kg, pH=7.9). At the end of the experiment, squid were photographed, morphometric data were collected using imagej™ software, and JMP ™ software was used for statistical analysis. Low DO and pH caused significant slowing of embryogenesis, delaying development by approximately 5-7 days. A second experiment, imposing low DO and pH separately, suggests that DO is responsible for most of the observed developmental delays. These delays may exert carry-over effects into the paralarval stage such as match-mismatch in timing of their hatching with availability of their prey, zooplankton, during their critical period of first feeding. If so, suitable habitat for market squid embryogenesis may be significantly compressed with only the most shallow areas (<20 m depth) producing paralarvae able to find adequate food for survival. Ongoing studies are using samples from these studies to investigate physiological effects on embryos and geochemical changes in statolith elemental composition during embryogenesis.
Gastropod statoliths are spherical biocarbonates formed throughout lifespan. The stability and homogeneity of these structures mineral matrix was characterized along their radiuses, using Nassarius reticulatus as a model. Generally, they were proved to be bimineralic. Two of the three CaCO3 crystalline polymorphs occurring in biocarbonates - aragonite and calcite - coexist along statoliths radiuses, being aragonite unequivocally the most abundant phase. The presence of a diffuse organic matrix was also perceived by the detection of a weak Raman band between 2800 and 3000 cm(-1) consistently observed along radiuses. Beyond the apparent stability and homogeneity, different crystalline orientations were disclosed by Raman Spectroscopy. A change in the intensity pattern of the features related to the lattice and bending modes of aragonite between different radiuses give new insights for a possible spherulitic-like growth of these structures. As expected from the relative homogeneity of both mineral and organic signals, there was no pattern on the distribution of Ca, O, Na and S along radiuses. However, a higher concentration of Sr occurs in growth rings (known as winter tags), corroborating the already described negative correlation between this element concentration in statoliths and temperature. Despite the apparent stability and homogeneity of the matrix along the lifespan, the periodic distribution of Sr potentially influences a dissimilar incorporation of trace elements in increments and growth rings. Since gastropods statoliths elemental fingerprinting was recently suggested as a new tool to monitor marine environmental changes, the pressing need for further studies on the incorporation of traces in these structures is highlighted.
Statolith trace elemental concentrations can be used as natural tracers to better understand life history and stock structure of squid. A highly variable Humboldt squid population was targeted to determine if ontogenic patterns could be revealed and to compare variations among squid collected from three geographic areas. Statoliths from Humboldt squid collected off Westport, WA; Oceanside, CA; and the Galapagos Islands were sampled for ten trace elements using laser ablation inductively coupled plasma mass spectrometry. Similar patterns were found for some elements despite geographic collection site distances indicating a potential to explain ontogenic shifts experienced by this species. Other elements displayed high variation in spatial pattern, which suggests the potential to distinguish among the squid collected from the three geographic regions and better understand stock structure. Within the California and Washington squid, eight of the elements varied in relation to calcium across the statolith with only yttrium and zirconium remaining statistically invariant. In addition to these two elements, copper and zinc also did not vary significantly across the statoliths collected from Galapagos squid. All elements demonstrate potential to influence a multivariate elemental fingerprint, which may provide a useful measure of population discrimination needed for stock assessment.
Variation in the chemical composition of fish otoliths has been used in recent years to address a range of ecological questions, including levels of stock mixing, variation in habitat use, and rates of larval exchange. While some of these questions have been answered with varying success, the degree to which discrete populations are connected via larval exchange remains unknown. To identify larval sources using natural variation in otolith chemistry, we must distinguish and measure the chemical composition of the otolith core, the portion of the otolith formed at the spawning site. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), we found that the core regions of otoliths from 6 different species of fishes were highly enriched in manganese (Mn), and elevated in magnesium (Mg) and barium (Ba), relative to adjacent regions of the otolith. These patterns were consistent for species drawn from different taxonomic groups, which inhabit temperate and tropical regions, are found in marine and freshwater, and utilize a variety of spawning modes. Variation among species in Mn concentration in the core also corresponds to maternal investment, measured by egg size. These data suggest that core enrichment may be a general characteristic of otoliths, and that the chemical composition of the otolith core is fundamentally different from other regions of the otolith. The localized elemental enrichment of the core underscores the importance of methods that analyze the core region in small, discrete samples if otolith chemistry is used to address questions of larval exchange among populations.
Internal standardization is a widely used method for compensating nonspectral interference in inductively coupled plasma (ICP) spectrometry. Emphasis is given on the choice of the suitable element and its specific spectral line as an efficient internal standard. This choice is the result of multi-variable evaluations and analytical applications. In inductively coupled plasma–atomic emission spectrometry (ICP-AES) and other spectrometric techniques several spectral lines of the same or different elements have been evaluated as potential internal standards. Yttrium spectral lines fulfill certain prerequisites and they are favored by a large number of researchers. In our discussed review, we present several reports of ICP-AES techniques that employ yttrium as the internal standard. These reports are classified according to specific sample origin and aim of the research.
Minor and trace elements incorporated into otoliths during growth may permanently record environmental conditions experienced by fishes. To determine the validity of this approach, we used laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to assay sectioned otoliths from juvenile Atlantic croaker (Micropogonias undulatus) collected from each of three sites in the Neuse River, North Carolina, and the Elizabeth River, Virginia. Elemental concentrations at the center of the otoliths did not differ between locations, although both Mg : Ca and Ba : Ca were significantly higher at the edge of otoliths from the Neuse River than from the Elizabeth River. Three of the elements (Mg : Ca, Sr : Ca, and Ba : Ca) showed significant variation across otoliths. Sr : Ca, and to a lesser extent Mg : Ca, showed progressive decreases as the fish moved from offshore spawning sites to estuarine nursery areas. The opposite pattern was shown by Ba : Ca. We hypothesize that these patterns were related to the elemental concentrations within oceanic and estuarine water masses. Although both Sr : Ca and Ba : Ca seem to be useful tracers of offshore-inshore migration of estuarine-dependent species, the sensitivity of the technique to more subtle changes in water chemistry remains to be determined.
Coral strontium/calcium ratios have been used to infer that the tropical sea surface temperature (SST) cooled by as much as
6°C during the last glacial maximum. In contrast, little or no change has been inferred from other marine-based proxy records.
Experimental studies of the effect of growth rate and the magnitude of intraspecific differences indicate that biological
controls on coral skeletal strontium/calcium uptake have been underestimated. These results call into question the reliability
of strontium/calcium-based SST reconstructions.
Coral strontium/calcium ratios have been used to infer that the tropical sea surface temperature (SST) cooled by as much as 6{degrees}C during the last glacial maximum. In contrast, little or no change has been inferred from other marine-based proxy records. Experimental studies of the effect of growth rate and the magnitude of intraspecific differences indicate that biological controls on coral skeletal strontium/calcium uptake have been underestimated. These results call into question the reliability of strontium/calcium-based SST reconstructions. 17 refs., 2 figs.
One hundred and fifty new measurements of the solubility of witherite were used to evaluate the equilibrium constant of the reaction BaCO3(cr) = Ba2+(aq) + CO32-(aq) between 0 and 90°C and 1 atm total pressure. The temperature dependence of the equilibrium constant is given by log K = 607.642 + 0.121098T - 20011.25/T - 236.4948 log T where T is in degrees Kelvin. The log K of BaCO3(cr), the Gibbs energy, the enthalpy and entropy of the reaction at 298.15 K are -8.562, 48.87 kJ · mol-1, 2.94 kJ · mol-1 and -154.0 J · mol-1 · K-1, respectively. The equilibrium constants are consistent with an aqueous model that includes the ion pairs BaHCO3+(aq) and BaCO30(aq) Three different methods were used to evaluate the association constant of BaHCO3+(aq), and all yielded similar results. The temperature dependence of the association constant for the reaction Ba2+(aq) + HCO3-(aq) = BaHCO3+(aq) is given by log KBaHCO3 + = -3.0938 + 0.013669T. The log of the association constant, the Gibbs energy, the enthalpy and entropy of the reaction at 298.15°K are 0.982, -5.606 kJ · mol-1, 23.26 kJ · mol-1 and 96.8 J · mol-1 · K-1, respectively. The temperature dependence of the equilibrium constant for the reaction Ba2+(aq) + CO2-3(aq) = BaCO03(aq) is given by log KBaCO3 0 = 0.113 + 0.008721T. The log of the association constant, the Gibbs energy, the enthalpy and entropy of the reaction at 298.15° K are 2.71, -15.49 kJ · mol-1, 14.84 kJ · mol-1 and 101.7 J· mol-1 · K-1. The above model leads to reliable calculations of the aqueous speciation and solubility of witherite in the system BaCO3-CO2-H2O from 0 to more than 90°C. Literature data on witherite solubility were re-evaluated and compared with the results of this study. Problems in the thennodynamic selections of Ba compounds are considered. Newer data require the revision of ΔfH° and ΔfG° of Ba2+(aq) to -532.5 and -555.36 kJ · mol-1, respectively, for agreement with solubility data.
For close to a century, recruitment of larvae to a local population has been widely accepted as a primary determinant of marine population dynamics. However, progress in elucidating the causes of recruitment variability has been greatly impeded by our ignorance of the sources of recruits. Although it is often assumed that recruitment is independent of local reproduction, there is increasing circumstantial evidence that physical and behavioural mechanisms could facilitate larval retention near source populations. To develop a direct method for reconstructing the dispersal history of recruiting larvae, we put forward the hypothesis that differences in nutrient and trace-element concentrations between coastal and open oceans could result in quantifiable differences in growth rate and elemental composition between larvae developing in coastal waters (locally retained) and larvae developing in open ocean waters (produced in distant locations). Using this method, we show that recruitment to an island population of a widely distributed coral-reef fish may often result from local retention on leeward reefs. This result has implications for fisheries management and marine reserve design, because rates of dispersal between marine populations-and thus recruitment to exploited populations-could be much lower than currently assumed.
The fish otolith (earstone) has long been known as a timekeeper, but interest in its use as a metabolically inert environmental recorder has accelerated in recent years. In part due to technological advances, applications such as stock identification, determination of migration pathways, reconstruction of temperature and salinity history, age validation, detection of anadromy, use as a natural tag and chemical mass marking have been developed, some of which are difficult or impossible to implement using alternative techniques. Microsampling and the latest advances in beam-based probes allow many elemental assays to be coupled with daily or annual growth increments, thus providing a detailed chronological record of the environment. However, few workers have critically assessed the assumptions upon which the environmental reconstructions are based, or considered the possibility that elemental incorporation into the otolith may proceed differently than that into other calcified structures. This paper reviews current applications and their assumptions and suggests future directions. Particular attention is given to the premises that the elemental and isotopic composition of the otolith reflects that of the environment, and the effect of physiological filters on the resulting composition. The roles of temperature, elemental uptake into the fish and the process of otolith crystallization are also assessed. Drawing upon recent advances in geochemistry and paleoclimate research as points of contrast, it appears that not all applications of otolith chemistry are firmly leased, although others are destined to become powerful and perhaps routine tools for the mainstream fish biologist.
Estuaries and associated seagrass habitats are thought to be important nursery areas for many fishes. There is, however, no direct evidence for movement of fish from estuaries to reefs. The aim of this study was to determine if populations of Achoerodus viridis (Labridae) on rocky reefs were sustained by (1) recruitment to estuarine seagrass habitat followed by movement to rocky reefs, (2) direct recruitment to rocky reefs, or (3) a combination of the two. Recruits were collected from estuarine seagrass and rocky reef habitats and elements in their otoliths analysed by inductively coupled plasma-mass spectrometry (ICP-MS) to determine if different 'elemental fingerprints' could be found. Higher concentrations of Zn, Al, Pb, Mn, Ba and Co were found in otoliths of recruits from estuarine seagrass habitat than in otoliths of recruits from coastal reefs, the latter 3 elements showing significant differences. Strontium occurred in significantly higher concentrations in otoliths of recruits from coastal reefs. Differences in concentrations of some elements in the otoliths of recruits allowed fish from the 2 environments to be distinguished with a high degree of accuracy, enabling the contribution of estuarine recruitment to sustaining reef populations to be determined. Elemental composition of the juvenile core of otoliths from adults on reefs was related to the composition of otoliths of recruits from each environment to identify historical recruitment environments. Discriminant function analysis showed that 41% of adults had recruited to estuaries and 59% had recruited to reefs, but these figures may be overestimated because adults must be assigned to 1 of the 2 groups. There was evidence to suggest that some adults may form a third intermediate group. Further validation (e.g, comparison with laser or probe based methods and tagging techniques) of our approach is warranted. Elemental techniques may have great potential for resolving fisheries problems and identifying broader scale effects of environmental degradation.
We investigated the hypothesis that strontium:calcium (Sr:Ca), cadmium:calcium (Cd:Ca), and barium:calcium (Ba:Ca) composition in scales reflects that of the ambient seawater in which fish were reared under controlled experimental conditions. Juvenile spot (Leiostomus xanthurus) were held in replicate tanks containing four different concentrations of Sr, Cd, and Ba maintained at either 20 or 25degreesC for a total of 42 days. The elemental composition of scales from these fish was analyzed at the termination of the experiment, using isotope dilution inductively coupled plasma mass spectrometry (ICP-MS). Sr, Cd, and Ba levels in the scales, expressed as ratios to Ca, were linearly related to environmental concentrations, indicating that the elements were incorporated inconstant proportions to levels in the ambient water. Temperature had no measurable effect on the uptake of Sr, Cd, or Ba into the scales. Finally, Sr:Ca and Ba:Ca ratios in scales were highly correlated with levels in the otoliths from the same treatment. In all, Sr:Ca, Cd:Ca, and Ba:Ca signatures in scales appear to be representative of the ambient environment and, therefore, may be useful for quantifying life-history characteristics of individual fish.
Larval statoliths of the temperate neogastropod Concholepas concholepas (Bruguière, 1789) appear to have great utility for reconstructing larval dispersal history. Hatch- ing marks on the statoliths seem to demarcate the natal core of recent recruits. Analysis of individual larval statoliths by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) indicates detectable levels of multiple trace ele- ments. Differences in Ba/Ca, Zn/Ca, and Pb/Ca in the larval core of C. concholepas statoliths from 3 geographically sepa- rated sites in Chile suggest these mineralized hard parts could function as natural tags of natal origin and hence be useful in ecological studies of larval dispersal pathways.
Marine protected areas (MPAs) have been proposed as one way to reduce the problems of overfishing and to respond to uncertainty in fisheries management. Many fisheries, including tropical and temperate reef fisheries, are inherently multispecies, multigear fisheries and are difficult to manage by traditional methods. Clearly, these fisheries should benefit from the establishment of no-take marine reserves, but the track record to date for fisheries benefits of MPAs is mixed or poorly documented. Because siting of reserves depends upon both scientific and sociological input, the lack of critical scientific information on source-sink population structure of reef fishes can potentially lead to MPA placement that can damage rather than enhance fisheries. In this paper, we develop a simple, spatially explicit model to address a series of hypotheses regarding MPA effects on fisheries. Our hypotheses include: (1) a system in which reserves are placed in source habitats is superior to one in which they are placed at random or in sink habitats; (2) the importance of source-sink population structure is increased if fishing effort is displaced rather than reduced; (3) as the proportion of the environment consisting of poor-quality (sink) habitat increases, proper siting of MPAs becomes increasingly important; and (4) if the environment contains directional currents, the spatial location of reserves will be critical to population enhancement. Our results suggest that, if reef fishes have source-sink population dynamics, siting reserves on the basis of sociological criteria alone may be risky. We need to understand source-sink population dynamics to site MPAs properly.
For many marine fishes, the literature contains indications of a surprising amount of local larval retention, even in species with long pelagic larval durations. In addition, there is circumstantial evidence that, before settlement, larvae accumulate in offshore areas. Proper design of marine reserves should include consideration of larval accumulation and retention. If retention and accumulation turn out to be common features of local marine population dynamics, areas important to these processes must be included in reserves and in the designation of essential fish habitat. If recruitment limitation is a common feature of the dynamics of local marine populations, it follows that maintenance of the supply of potential settlers is critical. Extensive larval retention may require major reassessment of fishery-enhancement models of marine reserves that depend on larval export for their effects.
The reaction rate and composition of calcite and aragonite overgrowths precipitated from seawater solutions of various salinities (i.e. S=5, 15, 25, 35, 44) were determined at 25°C and 10−2.5-atm. CO2 partial pressure using a constant disequilibrium seeded technique. The rate data were fitted to an empirical rate law of the form: where n is the empirical reaction order; and k is the rate constant. Calcite precipitation rates in seawater solutions do not vary appreciably as a result of salinity variations over the range investigated, while those for aragonite show an increase in going from the higher (i.e. S=35, 44) to the lower (i.e. S=5, 15, 25) salinity range. This study also confirms previously published findings that above a given saturation state (i.e. ) aragonite precipitates more rapidly than calcite at 25°C.The incorporation of Sr2+ in aragonite and Mg2+ in calcite overgrowths are independent of the precipitation rate. The partition coefficient of Sr2+ in aragonite is approximately equal to unity and is unaffected by salinity variations between 5 and 44. However, the Mg2+ partition coefficient in calcite, increases with decreasing salinity of the parent seawater solutions, possibly as a result of variations in the sulfate content of the solutions and solids.The experimental results were discussed in the context of a number of geological environments.
Corals offer a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi-decadal climate sensitivity is incomplete. In the eastern equatorial Pacific, coral isotopic records track variations in ENSO-related changes in sea-surface temperature; further west, corals record variability in sea-surface temperature and rainfall that accompanies zonal displacement of the Indonesian Low during ENSO events. These multi-century records reveal previously unrecognised ENSO variability on time scales of decades to centuries. Outside the ENSO-sensitive equatorial Pacific, long-term trends towards recent warmer/wetter conditions suggest the tropics respond to global forcings. New coral paleothermometers indicate that surface-ocean temperatures in the tropical southwestern Pacific were depressed by 4–6°C during the Younger Dryas climatic event and rose episodically during the next 4000 yr. High temporal-resolution measurements of Sr/Ca and in corals provide information about the surface-ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation. Radiocarbon measurements in corals, coupled with ocean circulation models, may be used to reconstruct near-surface ocean circulation, past mixing rates, and the distribution of fossil fuel CO2 in the upper ocean. Most recently, seasonal to interannual variations in the radiocarbon of corals from the equatorial Pacific have been linked to the redistribution of surface waters associated with the ENSO.
Minor and trace element analyses of fish otoliths (ear stones) may provide a high-resolution reconstruction of temperature histories and trace element compositions of aquatic systems where other environmental proxies are not available. However, before otoliths can be used to reconstruct water chemistry, it is essential to validate the assumption that trace metals in otoliths are deposited in proportion to dissolved concentrations in the ambient environment. We show, using a marine fish (Leiostomus xanthurus) reared in the laboratory under controlled experimental conditions, that otolith Sr/Ca and Ba/Ca ratios are deposited in proportion to their respective ratios in ambient waters. Temperature significantly affected Sr incorporation but did not affect Ba incorporation in otoliths. Sr/Ca partition coefficients (DSr) were 0.182 and 0.205 at 20°C and 25°C, respectively. The partition coefficients for Ba/Ca were 0.055 at 20°C and 0.062 at 25°C. A nonlinearity in the relationship between DBa and ambient Ba concentrations suggested that extrapolation beyond the Ba levels used in the experiment was not justified. On the basis of our results, it should be possible to reconstruct Sr/Ca and Ba/Ca levels in environments inhabited by fish based on otolith chemistry. Furthermore, Sr/Ca thermometry may also be possible using fish otoliths, but validation of the temperature dependence of Sr/Ca in otoliths will be required. We believe otoliths represent an excellent, and as yet underused, record of the physicochemical properties of both modern and ancient aquatic environments.
Radioisotopes of calcium and strontium were used to test for a relationship between the environmental concentrations of each element and their respective deposition rates on the otolith. On the basis of 45Ca and 89Sr assays, the rate of strontium deposition on the otolith was influenced by strontium concentrations in the water, while the rate of calcium deposition was affected neither by food nor water calcium concentrations. Thus, the deposition rate of strontium on the otolith at least partially reflects environmental availability, while that of calcium does not. Sources in the water contributed 75% of calcium and 88% of strontium to the sagittae of Nile tilapia, Oreochromis niloticus, with the remainder being provided by the diet.
Seawater Sr and Sr/Ca exhibit spatial gradients of 2–3% globally, with the deep ocean more enriched relative to the surface. In latitudinal transects, the highest surface values are found at high latitudes and associated with areas of upwelling. A pronounced upper ocean vertical Sr gradient is attributable to the production of celestite skeletons by surface-dwelling acantharia, coupled to a shallow dissolution cycle. The upper ocean residence time of Sr with respect to celestite cycling is much shorter than its global oceanic residence time. Although the magnitude of seawater Sr/Ca variability is relatively small, it is significant with respect to high-precision paleoceanographic applications. Sr/Ca gradients in the contemporary ocean also complicates evaluating Quaternary changes in seawater Sr/Ca that may have resulted from other processes, such as aragonite recrystallization during sea-level low stands.
Coupled radiocarbon and thorium-230 dates from benthic coral species reveal that the ventilation rate of the North Atlantic
upper deep water varied greatly during the last deglaciation. Radiocarbon ages in several corals of the same age, 15.41 ±
0.17 thousand years, and nearly the same depth, 1800 meters, in the western North Atlantic Ocean increased by as much as 670
years during the 30- to 160-year life spans of the samples. Cadmium/calcium ratios in one coral imply that the nutrient content
of these deep waters also increased. Our data show that the deep ocean changed on decadal-centennial time scales during rapid
changes in the surface ocean and the atmosphere.
Magnesium/calcium data from planktonic foraminifera in equatorial Pacific sediment cores demonstrate that tropical Pacific sea surface temperatures (SSTs) were 2.8 degrees +/- 0.7 degrees C colder than the present at the last glacial maximum. Glacial-interglacial temperature differences as great as 5 degrees C are observed over the last 450 thousand years. Changes in SST coincide with changes in Antarctic air temperature and precede changes in continental ice volume by about 3 thousand years, suggesting that tropical cooling played a major role in driving ice-age climate. Comparison of SST estimates from eastern and western sites indicates that the equatorial Pacific zonal SST gradient was similar or somewhat larger during glacial episodes. Extraction of a salinity proxy from the magnesium/calcium and oxygen isotope data indicates that transport of water vapor into the western Pacific was enhanced during glacial episodes.
Cadmium and manganese comprise paleo-upwelling indicators that display great sensitivity in the eastern tropical Pacific Ocean. Barium levels in Caribbean corals reflect seasonal river discharge from South America that may in turn be modulated by the El Nino - Southern Oscillation. Manganese and barium may also track lateral movement of water masses as in continental shelf water advection or river plume migration. Finally, coralline cadmium is seen to respond to ENSO-driven rainfall anomalies in the western equatorial Pacific, though the mechanism behind this response is not clear. -from Authors
An active couple exists between the atmosphere and surface ocean to produce regional-to-global changes in earth's climate. While numerous terrestrial recording systems have revealed meteorological perturbations over the continents, however, historical changes in the surface ocean are largely unknown. This contribution describes recent efforts to develop new paleochemical indicators trapped in the aragonite lattice of reef-building corals. The methodology requires chance combinations of circumstances (crystal lattice compatibility and mechanisms that promote variable surface ocean composition) and great analytical care, yet several applications have surfaced in relation to El Niño. Cadmium and manganese comprise paleo-upwelling indicators that display great sensitivity in the eastern tropical Pacific Ocean. Barium levels in Caribbean corals reflect seasonal river discharge from South America that may in turn be modulated by the El Niño -Southern Oscillation. Manganese and barium may also track lateral movement of water masses as in continental shelf water advection or river plume migration. Finally, coralline cadmium is seen to respond to ENSO-driven rainfall anomalies in the western equatorial Pacific, though the mechanism behind this response is not clear.
The orthorhombic carbonates are considered including aragonite, the other common polymorph of CaCO//3, and its rarer isomorphs, strontianite (SrCO//3), witherite (BaCO//3), and cerussite (PbCO//3). These minerals had important roles in the discovery of polymorphism. Orthorhombic carbonates have been studied by a variety of techniques to yield information on the temperatures and pressures of crystallization, fluid chemistry, source material, and isotopic age. All of them have been exploited commercially - aragonite as a pigment, filler and biodegradable bone implant, and the others as ores of their metals. Witherite has seen more varied uses as rat poison and drilling mud. Refs.
Shells of the common cockle Cerastoderma edule have been analysed using Laser Ablation Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) for a suite of elements (Pb, Cu, As, Zn and U). The samples of C. edule were obtained from four sites in the British Isles, two facing the Atlantic and two adjacent to the Irish Sea. The LA-ICP-MS technique, permits high resolution examination of the relationship between the concentrations of elements in the hard parts and that in the environment. This study shows that this bivalve can be used as a biomonitor of pollution. All four areas under investigation are affected by anthropogenic pollution, in particular Zn and Cu, and are characterized by short-term extreme pollution events. Furthermore, high levels of U are recorded from the cockles sampled from the sites adjacent to the Irish Sea, probably related to a combination of both natural and industrial effluents discharged into the area.
Cross sections of two Mercenaria mercenaria shells, one modern and one Pleistocene, and one modern Spisula solidissima shell were analyzed for trace metals using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). These data are coupled with 18O16O ratio profiles, which are used as a temperature proxy to determine the season of growth for a given shell parcel. The shells show Sr and Ba fluctuations in regular annual patterns. Seasonal Sr decreases associated with the winter dormant period in Mercenaria, and with the summer growth decrease in Spisula indicate that kinetic control (growth rate) plays a more important role than temperature in the incorporation of this element. Barium exhibits sharp increases that are likely linked to periods of intense phytoplankton productivity.This application of LA-ICP-MS to the analysis of mollusk shells for documenting ontogenetic trends demonstrates the power of this technique for extracting geochemical information.
Because strontium and magnesium occur in seawater with nearly constant ratios to calcium, variations in Sr/Ca and Mg/Ca in modern foraminifer shells are due to the influence of environmental parameters on calcification. The authors have cultured two species of planktonic foraminifera, Globigerina bulloides and Orbulina universa, to establish the influence of temperature, pH, and salinity. Experimental results indicate that temperature is the primary control on shell Mg/Ca and that shell Mg/Ca increases exponentially by about 8 to 10% per {degree}C. The exponential rise in shell Mg with temperature mirrors the results from inorganic precipitation experiments and suggests at least partial thermodynamic control on Mg incorporation. Both seawater pH and salinity are secondary influences on shell Mg/Ca: {minus}6% per 0.1 pH unit increase and +4% per salinity unit increase. Shell Sr/Ca responds far more weakly to environmental parameters, and the small range observed in shell Sr/Ca relative to measurement precision of the ICP-MS method used here limits how well controls on shell Sr can be determined. Higher temperature, salinity, and pH all appear to increase shell Sr/Ca, most likely through the kinetic influence of calcification. Culturing results demonstrate the potential of Mg/Ca in G. bulloides as a paleothermometer. The culturing results suggest that the standard error of Mg paleothermometry is {+-}1.1 C, but when the secondary effects of salinity and pH are considered the error increases to {+-}1.3 C.
Minor and trace elements incorporated into otoliths during growth may permanently record environmental con- ditions experienced by fishes. To determine the validity of this approach, we used laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) to assay sectioned otoliths from juvenile Atlantic croaker (Micropogonias undulutus) collected from each of three sites in the Neuse Rivet; North Carolina, and the Elizabeth River, Virginia. Elemental concentrations at the center of the otoliths did not differ between locations, although both Mg : Ca and Ba : Ca were significantly higher at the edge of otoliths from the Neus: River than from the Elizabeth River. Three of the elements (Mg : Ca, Sr : Ca, and Ba: Ca) showed significant variation across otoliths. Sr : Ca, and to a lesser extent Mg : Ca, showed progressive decreases as the fish moved from offshore spawning sites to estuarine nursery areas. The opposite pattern was shown by Ba: Ca. We hypothesize thal: these patterns were related to the elemental concentrations within oceanic and estuarine water masses. Although both Sr : Ca and Ba: Ca seem to be useful tracers of offshore-inshore migration of estuarine-dependent species, the sensitivity of the technique to more subtle changes in water chemistry remains to be determined.
Calcium carbonate was precipitated from sea water by the slow addition of dilute Na 2 CO 3 solutions. The distribution coefficient k Sr A , defined by the ratio of m Sr 2+ / m Ca 2+ in precipitated aragonite to m Sr 2+ / m Ca 2+ in the solutionfrom which the aragonite was precipitated, was found to decrease linearly with increasing temperature from 1·17 ± 0·04 at 16°C to 0·88 ± 0·03 at 80°C. Above 30°C aragonite was the only phase precipitated; at 16°C a calcite containing 8-10 mol % MgCO 3 commonly accompanied aragonite; at 3°C calcite containing less than 1 mol % MgCO 3 , vaterite, or CaCO 3 ·H 2 O were dominant phases, while aragonite was usually absent. It is shown that the value of k Sr A depends on the kinetics and mechanism of crystal growth, and that this must be true for all distribution coefficients determined under conditions in which the rate of crystal growth is greater than the rate of diffusion within growing crystals. Although the kinetic dependence of distribution coefficients limits the usefulness of the chemical composition of minerals in interpreting the chemistry of the environment in which they were formed, some distribution coefficients appear to be sufficiently insensitive to rates of crystal growth, so that their use is virtually exempt from this limitation.
The Japanese Common Squid, Todarodes pacificus Steenstrup, 1880, moves vertically in the water column in time with the natural day–night cycle and this exposes the animal to considerable temperature changes throughout the 24-h period. We considered that this behavior could result in daily fluctuations of the statolith strontium/calcium ratio (Sr/Ca ratio), if this ratio is thermally sensitive, as is found for coral skeletons. To investigate this hypothesis, Japanese Common Squid were reared under constant temperature (15 °C) for 64 days and their statolith Sr/Ca ratios, in the area that had been deposited while in captivity, measured by wavelength dispersive spectrometer. Small repetitive fluctuations were observed in the statolith Sr/Ca ratios of the captive squid (N=5, 2.7-day cycle) but similar fluctuations were also observed in the statoliths of Japanese Common Squid collected from the wild (N=5, 2.4-day cycle). These results imply that the daily vertical movements in the water column are not reflected in the statolith Sr/Ca ratios in the Japanese Common Squid. The observed small repetitive fluctuations are discussed in relation to the periodic feeding activity of the captive squid (1.9-day cycle).
The concentrations of elements and isotopes in fish otoliths may provide a method of reconstructing movements of fish by differentiating between water bodies of different temperatures and salinities. However, before otoliths can be used to reconstruct environmental histories of fish, it is necessary to assess the effects of seawater temperature and salinity on otolith microchemistry. Using controlled laboratory experiments, juvenile black bream, Acanthopagrus butcheri (family Sparidae), were reared for 50 days in aquaria of varying temperatures and salinities using three experimental designs: temperature x salinity, temperature only, and salinity only. Temperature and salinity interacted to significantly affect the elemental concentration ratios of Sr:Ca and Ba:Ca and the concentrations of isotopes delta(13)C and delta(18)O in otoliths. The single-factor experiments showed that temperature significantly affected the concentration ratios of Sr:Ca and Ba:Ca and the concentrations of delta(13)C and delta(18)O in otoliths, whereas salinity alone did not affect the concentration ratios of any elements but did affect both isotopes. The concentration ratios of Mg:Ca and Mn:Ca varied considerably among fish within the same treatment level and showed little or no effects due to temperature and (or) salinity. The significant interactive effects of temperature and salinity on otolith microchemistry highlight the need for a multifactorial approach to testing hypotheses regarding the environmental histories of fish.
The early life history of many marine benthic invertebrate and fish species involves a planktonic larval stage that allows exchange of individuals among separated adult populations. Here, we demonstrate how natural and anthropogenic trace elements can be used to determine larval origins and assess bay-ocean exchange of invertebrate larvae. Trace elements can be effective site markers for estuaries because run-off and pollutant loading often impart distinct elemental signatures to bay habitats relative to nearshore coastal environments. Crab larvae originating from San Diego Bay (SDB) were distinguished from those originating in neighboring embayments and exposed coastal habitats by comparing multiple trace-element concentrations (''fingerprints'') in individuals. Discriminant function analysis (DFA) was used to characterize stage I zoeae of the striped shore crab, Pachygrapsus crassipes,of known origin (reference larvae) via trace-elemental composition (i.e., Cu, Zn, Mn, Sr, Ca). Linear discriminant functions were used to identify the origin and characterize the exchange of stage I P. crassipes zoeae between SDB and the nearshore coastal environment during one spring tidal cycle. Elemental fingerprinting revealed that most (87%) of the stage I larvae collected at the bay entrance during the flood tide were larvae of SDB origin that were reentering the bay. Nearly one third of zoeae sampled (32%) at the entrance during ebb tide were coastal larvae leaving the bay and returning to open water. The observed bidirectional exchange contrasts with the unidirectional transport of zoeae out of the bay predicted from stage I vertical migratory behavior. Because P. crassipes zoeal survivorship is lower in SDB than in coastal waters, bay-ocean exchange has significant implications for the dynamics of P. crassipes populations. Trace-elemental fingerprinting of invertebrate larvae promises to facilitate investigations of many previously intractable questions about larval transport and dynamics.
Though many studies on the Mg contents in the calcitic tests of foraminifers exist, the processes controlling its uptake are still a matter of debate. Laboratory cultures offer an excellent opportunity to reveal these mechanisms. The Mg concentrations within single chambers of the planktic foraminifer Globigerinoides sacculifer (BRADY) maintained under controlled laboratory conditions were measured (1) at variable temperatures (19.5–29.5 °C) and constant salinity and (2) at variable salinity (22–45‰) and constant temperature.
The trace metal composition of foraminiferal shells preserved in
deep-sea sediments is a critical source of data used in reconstructing
the physical and chemical characteristics of ancient oceans. However,
paleoceanographic information derived from these tracers is limited by
the accuracy with which calcite shells record ambient seawater chemistry
and the question of whether changing environmental conditions or
interspecific differences affect shell chemistry. Experiments with
living foraminifera are one of the most direct ways to quantitatively
evaluate the relationship between shell and seawater chemistry and the
influence, if any, of environmental variables. Here we present results
from laboratory experiments on the living planktonic foraminifers
Globigerina sacculifer and Orbulina universa that demonstrate that
precipitated shells provide an accurate record of seawater barium, a
tracer used in reconstructing nutrient and alkalinity distributions in
past oceans. On the basis of culturing data at 29°C, 36.7‰
salinity, the best estimate of the partition coefficient D relating
foraminifera shell Ba/Ca to seawater Ba/Ca is 0.147 ± 0.004. Data
show that when environmental conditions are held constant, there is no
significant variability in Ba uptake between individual shells of one or
both species. Results also demonstrate that temperature varying over a
7°C range and salinity varying over a 3‰ range do not
appreciably influence Ba uptake.
LATTICE-BOUND cadmium in scleractinian corals has been shown to be a sensitive tracer of historical changes in the nutrient content of surface waters1,2. Barium also substitutes into the lattice of aragonite reef-building corals because there is solid solution between orthorhombic BaCO3 (witherite) and CaCO3(aragonite)3. It is expected that the substitution should be proportional to the Ba content of sea water, which increases from low values in warm surface waters to higher values in cold deep waters. Here we present a high-resolution coralline Ba record from the Galapagos Islands spanning the period 1965-1978. Coralline Ba/Ca tracks historical sea surface temperatures, reflecting the vertical displacement of warm nutrient-poor surface waters by cold, nutrient-rich source waters. Differences between coralline Ba and Cd records may be due to preferential uptake of Cd by phytoplankton during times of lower surface nutrients.
We have sought to directly test the assumption that the ratio of foraminifera shells is proportional to the ratio of the seawater in which the shells precipitated via experiments with living planktonic foraminifera. Specimens of the symbiont-bearing species, Orbulina universa, were grown in seawater with five different Ba concentrations at a temperature of 22°C. Individual foraminifera shells (spherical chambers) were then cleaned and analyzed for . We found that the response for Ba incorporation is linear within and somewhat above the range of Ba concentrations found in the ocean. The calculated distribution coefficient for Ba incorporation lies between 0.14 and 0.17. The value determined previously by comparison of core-top fossil planktonic foraminifera and surface water compositions was 0.19 ± 0.05. Foraminifera grown under low-light conditions to simulate reduced symbiont photosynthetic activity did not have significantly different . This suggests that for this species, biogenic precipitation rates of calcite varying in response to changing light levels do not affect the degree of Ba discrimination. Earlier observations of Ba incompatibility and lack of substitution in inorganically precipitated calcite at higher Ba activities do not apply to coprecipitation of Ba in the planktonic foraminifera Orbulina over the range of Ba concentrations found in seawater.
The utility of Sr/Ca ratios in otoliths as indicators of thermal history in fish was investigated for juvenile Girella elevata. There was no direct relationship between ratios of Sr/Ca and temperature of the water, as has been assumed in many previous studies. Sr/Ca ratios did not decrease when water temperature was elevated from 19 to 28° C. Elevation of ambient Sr levels in the sea water caused a significant increase in Sr/Ca ratios in otoliths, and there was a detectable increase in Sr/Ca ratios in otoliths of some individuals fed an Sr-enriched diet. Multiple factors may influence natural Sr/Ca ratios in otoliths of juvenile G. elevata and their interactions make it difficult to interpret the chronology of conditions experienced by an individual fish during early life in the pelagic or benthic environment.
Shells of probable former living communities ofDreissena polymorpha were found within sediments of the shallow polytrophic to hypertrophic hard water Lake Breitling (Havel-Lake system, Germany).
Corresponding sediments have been deposited between approximately 1940 and 1970 and reflect increasing eutrophication and
heavy metal pollution of the Lake during this period (Schettler, 1992). Single shells from various sediment depths were analysed
by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) along a line on the outer part of the shell. The
response of these freshwater mussels to increasing heavy metal pollution is clearly reflected in the distribution of Pb, Cu,
Cd and Zn within their valves. In general, Cd, Cu, Pb and Zn contents are lower, and the distribution more even, in the outer
parts of the deepest (oldest) shells compared to shells from higher in the cored sediments. Notably higher contents of Cu,
Pb and Zn were recorded from the central (umbonal) part of the more recent shells, but this behaviour is not recorded for
Cd. Metabolic changes brought on by worsening environmental conditions are proposed to explain this phenomena. Acidity produced
during anaerobic metabolism can be neutralised by dissolution of the carbonate part of the shell. Copper, Zn and Pb, which
show an affinity for the organic component of the shell, may thus accumulate by repeated dissolution and reprecipitation of
the shell during the lifetime of an individual organism. Cadmium, which is bound mainly in the aragonite of the shells, is
released during the dissolution of carbonate and is not concentrated in the umbonal area of the shell.
Seasonal and ontogenetic patterns in estuarine and coastal migrations of anadromous fish species have important consequences to their survival, growth, recruitment, and reproduction. We tested the hypothesis that otolith (sagitta) microchemistry can document the environmental history of individual fish across an estuarine salinity gradient. Juvenile striped bass, Morone saxatilis (Walbaum), (80 days posthatch) were reared for 3 wk in aquaria at two temperatures and six salinities. The ratio of strontium/calcium () deposited in the sagittal otoliths of reared juveniles was positively related to salinity. Temperature and growth rate had relatively minor, but significant effects on the ratio. In a second experiment, juveniles (80 days posthatch) were exposed to increasing salinity (0 ppt to 25 ppt) and then decreasing salinity (25 ppt to 0 ppt) over a 20-wk period. Electron microprobe examination of the otoliths from these juveniles showed a gradual rise and decline in during the experimental period which corresponded directly with experimental changes in salinity. Field data on subadult and adult striped bass corroborated the laboratory analyses and indicated a logistic relationship between ambient salinity and otolith ratio. Verification studies support the use of otolith microchemistry to measure migratory schedules and habitat utilization patterns in anadromous striped bass populations.
The experimental distribution coefficients, K′d, for trace elements in carbonate minerals show a systematic pattern of behavior that differs from that expected if the distribution were controlled by equilibrium thermodynamics. Regression of experimental distribution coefficients, K′d, from the literature shows that they correlate well with the quotient of the solubility products of the trace element and host carbonate. However, the slope of the correlation line differs from that predicted by equilibrium theory in a way that suggests that the experiments are affected by a kinetic process, whereby the trace element is incorporated into the growing carbonate crystal at a rate that is either faster or slower than the incorporation of Ca. The correlations predict that the K′d for elements that form rhombdohedral carbonates (e.g., Cd, Zn, Cu, Mn, etc.) is expressed by for calcite and for siderite. These correlations can be used to estimate the K′d values for cases where no experimental data are available, including for other phases and other temperatures.Thus, the experimental K′d values can be used to understand general trends in trace element behavior. Analysis of K′d for calcite shows that this mineral can effectively sequester a variety of toxic cations (e.g., Pb, Cd, Cu, etc.) from solution, so precipitation of calcite from contaminated solutions may provide an effective method of environmental remediation. On the other hand, values of K′d should be used with caution when interpreting ancient geochemical environments for carbonates, because K′d values are strongly rate-dependent and the rates of mineral precipitation are seldom known.
Laboratory culturing is a direct means of determining Cd uptake in shells of planktonic foraminifera. We employed a new stable isotope technique using both 110Cd and 111Cd to assess uptake in the symbiont bearing species, Orbulina universa, and the nonsymbiont bearing species, Globigerina bulloides. In certain experiments with G. bulloides the three endmember isotope dilution method was combined with a recently described 48Ca labeling technique.Shells of Orbulina universa cultured under a 12 h high light:12 h dark cycle are found to incorporate very little Cd. Foraminifera can be induced to take up slightly more Cd by growth under 24 h darkness or under a 12 h high light:12 h dark cycle with exposure to the photosynthesis inhibitor, DCMU. These results demonstrate that O. universa under-represents the Cd concentration of seawater in which the shell is precipitated. Additionally, the results suggest a previously unknown influence of symbiotic dinoflagellates on foraminiferal shell chemistry. There are two different mechanisms by which symbionts might play a role in influencing Cd uptake in O. universa: (1) algal sequestration and removal of Cd from the foraminiferal calcification microenvironment or (2) photosynthetic enhancement of calcification rate, leading to Cd exclusion. If these results apply generally to bioactive trace metal uptake by dinoflagellate-bearing planktonic foraminifera, they suggest that shells of species such as O. universa only record qualitative changes in surface water metal concentrations. The response for Cd uptake in nonsymbiont bearing G. bulloides (cultured under a 12 h high light: 12 h dark cycle) appears linear within and slightly above the range of Cd concentrations found in the modern ocean, with an effective partition coefficient equal to 1.9 ± 0.2 (95% C.I.). The Cd partition coefficient determined for G. bulloides falls within the range of DCd previously found for fossil benthic foraminifera but is twenty times higher than that for O. universa (Dcd = 0.095 ± 0.021 (95% C.I.)) grown under identical culture conditions. Because G. bulloides appears to reliably record seawater Cd concentrations, it should be suitable for accurate paleoreconstructions of surface water Cd and PO43− concentrations.
The effects of temperature, somatic growth, otolith growth, condition factor, RNA/DNA ratio, age and season on the incorporation of Sr, Na, K and S into the sagittal otoliths of Australian salmon and blue grenadier were investigated by a combination of laboratory-rearing experiments and monthly collections of wild fish. Microchemical analyses of otolith chemistry were carried out with a wavelength dispersive electron microprobe. There were significant differences in otolith Sr/Ca ratios among Australian salmon maintained in the laboratory at different temperatures and a slight positive correlation with temperature, but there was no evidence for a linear relationship between Sr/Ca ratio and temperature. Biologically significant relationships between other factors were not evident in laboratory-maintained fish. Furthermore, the variability of elemental ratios within temperature treatments and within individual otoliths was very significant. It is hypothesized that seasonal variations in otolith chemistry in both wild blue grenadier and Australian salmon are partly due to seasonal changes in growth rates and/or reproductive investment. There were highly significant correlations between otolith chemistry and fish age in wild blue grenadier and these were largely explained using a similar rationale regarding growth rates and reproduction. It is hypothesized that the seasonal and age-related variation in otolith Sr content is largely the result of changes in the proportions of free and bound Ca and Sr present in the blood plasma and that this is in turn a function of the quantity and type of proteins present in the plasma. Data on the level of Sr present in the saccular endolymph and the sagittae of 12 fish species showed that there was a very strong relationship between the composition of the endolymph and the otoliths. Because of their variability, otolith microchemistry data indicate the need for large sample sizes, validation experiments and extreme caution when investigating the relationship between otolith microchemistry and physiology, life-history stage and environment.
Barium profiles at the Atlantic stations of the Geochemical Ocean Sections (GEOSECS) Program are remarkably similar to those for silicate and alkalinity. In nutrient depleted surface waters barium ranges between 36 and 44 nm kg−1: the Arctic overflows have values between 44 and 49 nm kg−1 and the Antarctic Bottom Water 100 to 106 nm kg−1. Both barium and silica behave non-conservatively in basins with restricted circulation—the Greenland and Norwegian seas and the Angola Basin—with anomalies of up to 1, 2 and 7 nm Ba kg−1, respectively. There is extensive in situ production of silica and barium in the bottom waters of the Weddell Sea Basin, the silica anomaly ranging up to 35 μm kg−1 and that for barium to 15 nm kg−1. Barium behaves uniquely only in the upper waters. At tropical and temperate latitudes there is commonly a minimum of several nannomoles per kilogram in the uppermost thermocline, often associated with the high salinity core of the Sub-Tropical Underwater. In the Circumpolar Current the depletion in surface silica is associated with only a minor reduction in barium. The values at <5 μm Si kg−1 are about 30 nm kg−1 higher than those at lower latitudes. The important question of the removal mechanism is not resolved from the profile data.
Recent developments in inductively coupled plasma mass spectrometry (ICP-MS) make it possible to simultaneously measure a suite of trace elements of paleoceanographic interest in foraminifera shells from deep-sea sediments. Here we present an ICP-MS method that allows determination of precise Cd/Ca, Ba/Ca, Sr/Ca and Mn/Ca ratios in purified foraminifera shell samples as small as 25 μg. The method utilizes a combination of isotope dilution for Ba and Cd determination and internal standardization for Ca and Sr determination. Long term reproducibility of the method is 2–3% for the elemental ratios. The principal advantages of the method are that all four elemental ratios of paleoceanographic interest are generated simultaneously for a single sample of purified foraminiferal carbonate, minimizing sample size requirement, reducing analysis time, and improving correlation between proxies.
A method has been developed using laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) for rapid high resolution analysis of B, Mg, Sr, Ba, and U in corals. Corals represent a challenge for a microbeam technique due to their compositional and structural heterogeneity, their nonsilicate matrix, and their unusual range of trace element compositions relative to available standards. The method employs an argon-fluoride excimer laser (λ = 193 nm), masked to produce a beam 600 μm wide by 20 μm across to average ablation sampling over a range of structural features. Coral sections are scanned at a constant rate beneath the laser to produce a continuous sampling of the coral surface. Sensitivity drift is controlled by careful preconditioning of the ICP-MS to carbonate material, and standardisation is carried out by bracketing each traverse down the coral sample by analyses of a CaSiO3 glass synthesised from coral powder. The method demonstrates excellent reproducibility of both the shape and magnitude of coralline trace element profiles, with typical precisions of between 1.0 and 3.7% based on analysis of the synthetic standard. Accuracy varies between 3.8% for B and 31% for U. Discrepancies are attributed to heterogeneities in the synthetic standard, and matrix differences between the silicate standard and carbonate sample. The method is demonstrated by analysis of a coral collected from Australia’s Great Barrier Reef near a weather station recording in-situ sea-surface-temperature (SST). The elements B, Mg, Sr, and U show seasonal compositional cycles, and tentative calibrations against SST have been derived. Using independent ICP-MS solution estimates of the coral composition to correct for standardisation uncertainties, the following calibrations have been derived:
Taking advantage of the availability of a continuous sea surface temperature (SST) record at Kenting, southern Taiwan, we have carried out a calibration of D[Sr/Ca]-SST (D: distribution coefficient) relationships for Porites lobata and P. lutea. Between 22°C ∼ 28°C, the best fitting linear relationships for the two species agree within their respective errors with a maximum deviation less than 0.3°C. Our calibration overlaps with the only published calibration for Porites (deVilliers et al., 1994) but is somewhat less temperature sensitive. The maximum temperature differences for the two calibrations between 21°C and 27°C are ± 1.2°C. The D-SST relationship calculated using the data of
[2] and [3] and their unpublished seawater data lies between these two calibrations. Our calibration removes some discrepancies previously described in the studies of McCulloch et al. (1994a) on the Great Barrier Reef and of Min et al. (1995) on New Caledonia. We found little growth rate effect on the calibration for P. lutea between 18 mm/yr and 23 mm/yr. We have also monitored the seawater [Sr/Ca] for the entire 1993. The observed variation of 0.033 mmol/mol can cause a temperature artifact of 0.7°C and is thus a dominant error in using this new paleo-thermometer. To carry out this experiment, we have developed a microsurgical technique that can be used to sample corals at better than 0.15 mm resolution. The analytical precision should ultimately allow SST reconstruction of better than 0.2°C. Furthermore, the insensitivity of the calibration against growth rate variation and species differences suggests a promising future for this new thermometer, in contrast to the pessimism of deVilliers et al. (1995). However, inter-laboratory differences and the question of seawater [Sr/Ca] variation need to be addressed first. We recommend a single SST calibration for the Sr/Ca thermometer on coral Porites: Sr/CaN = 10.286–0.0514 × SST (N: normalized to Hawaii seawater [Sr/Ca] = 8.510 mmol/mol) or D[Sr/Ca] = 1.2077 – 0.006011 × SST.
The high precision measurement of the Sr/Ca ratio in corals has the potential for measuring past sea surface temperatures at very high accuracy. However, the veracity of the technique has been questioned on the basis that there is both a spatial and temporal variation in the Sr/Ca ratio of seawater, and that kinetic effects, such as the calcification rate, can affect the Sr/Ca ratio of corals, and produce inaccuracies of the order of 2–4 °C. In the present study, a number of cores of the massive hermatypic scleractinian coral Porites, from the central Great Barrier Reef, have been analyzed for Sr/Ca at weekly to monthly resolution. Results from a 24 year record from Myrmidon Reef show an overall variation from 22.7 °C to 30.4 °C. The record shows a warming/cooling trend with maximum warming centred on the 1986–1987 summer. While some bleaching was reported to have occurred at Myrmidon Reef in 1982, the Sr/Ca record indicates that subsequent summer temperatures were much higher. The 4.5 year record from Stanley Reef shows a maximum SST of 30 °C during the 1997–1998 El Niño event. The calibrations from Myrmidon and Stanley Reefs are in excellent agreement with previously published calibrations from nearby reefs. While corals do not calcify in equilibrium with seawater due to physiological control on the uptake of Sr and Ca into the lattice of coralline aragonite, it can be argued that, provided only a single genus such as Porites sp. is used, and that the coral is sampled along a major vertical growth axis, then the Sr/Ca ratio should vary uniformly with temperature. Similarly, objections based on the spatial and temporal variability of the Sr/Ca activity ratio of seawater can be countered on the basis that in most areas where coral reefs grow there is a uniformity in the Sr/Ca activity ratio, and there does not appear to be a change in this ratio over the growth period of the coral. Evidence from several corals in this study suggest that stress can be a major cause of the breakdown in the Sr/Ca–SST relationship. Thermal stress, resulting from either extremely warm or cool temperatures, can produce anomalously low Sr/Ca derived SSTs as a result of the breakdown of the biological control on Sr/Ca fractionation. It is considered that other stresses, such as increased nutrients and changes in light intensity, can also lead to a breakdown in the Sr/Ca–SST relationship. Two of the main issues affecting the reliability of the Sr/Ca method are the calibration of the Sr/Ca ratio with measured SST and the estimation of tropical last glacial maximum (LGM) palaeotemperatures. Instead of producing a constant calibration, just about every one published so far is different from the others. What is obvious is that for most calibrations while the slope of the calibration equation is similar, the intercepts are not. While the cause for this variation is still unknown, it would appear that corals from different localities around the world are responding to their own particular environment or that certain types of environments exert a control on the corals’ physiology. Sr/Ca derived SST estimates for the LGM and deglaciation of 5 °C–6 °C cooler than present are at odds with estimates of 2 °C–3 °C cooling by other climate proxies. The apparent lack of reef growth during the LGM suggests that SSTs were too cold in many parts of the tropics for reefs to develop. This would lend support to the idea that tropical SSTs were much cooler than what the CLIMAP data suggests.
A new method was developed for rapid and precise simultaneous determination of Mg/Ca, Sr/Ca, Mn/Ca, Cd/Ca, Ba/Ca and U/Ca ratios in foraminiferal shells using sector field inductively coupled plasma mass spectrometry (ICPMS). Element/calcium ratios were determined directly from intensity ratios using external, matrix-matched standard to correct for instrumental mass discrimination. Because of large differences in the abundance of chemical constituents of the foraminiferal shell, major elemental ratios were determined in analog mode (using (24)Mg, (43)Ca, (44)Ca, (55)Mn, and (88)Sr) whereas trace elemental ratios were determined in pulse-counting mode (using (111)Cd, (138)Ba, (238)U, and the low-abundance (46)Ca isotope). Matrix-induced variations in mass discrimination over a calcium concentration range of 2.0-24.5 mM were observed only for Mg/Ca and Cd/Ca ratios. However, these effects are negligible if the samples and standard calcium concentration are within a factor of 2-3. Multiratio method reproducibility was better than previously reported for other ICPMS methods yielding precision (1σ) of Sr/Ca = 0.45%; Mg/Ca = 0.45%, Mn/Ca = 0.8%, Cd/Ca = 1.7%, Ba/Ca = 0.7%, and U/Ca = 1.4% for foraminifera samples as small as 25 μg. Using this approach for a single-ratio analysis, Sr/Ca ratios were determined with precision of 0.06% (1σ) on carbonate samples as small as a single foraminifera shell (<10 μg). The new method is more sensitive, more precise, and simpler to use than previously available ICPMS techniques. It provides an efficient tool for simultaneous determination of several elemental ratios of paleoceanographic interest in a single foraminiferal sample, thereby reducing overall sample size requirement and analysis time.
Thesis (Ph. D.)--University of California, Santa Barbara, 2002.