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ABSTRACT: Dietary methylmercury (MeHg) uptake by fish in relation to life stage, species, and level of exposure is poorly understood in lower trophic levels, particularly in estuarine species. The authors compared accumulation of dietary MeHg as well as sensitivity (survival and growth) to dietary MeHg exposure in two species of estuarine forage fish, Cyprinodon variegatus and Menidia beryllina. Fish were fed one of five dietary MeHg concentrations (ranging from 0.04 to 14 µg/g dry wt) over a period of 70 d. Growth rate and the level of dietary exposure influenced MeHg tissue concentrations in both species. Mercury in the diet exhibited a strong linear relationship with fish Hg tissue concentrations. Additionally, the authors found that M. beryllina was more sensitive to dietary MeHg exposure than C. variegatus. Both species showed some decreases in growth related to MeHg exposure, although these patterns were not consistent among treatments. Overall, C. variegatus and M. beryllina were found to have a high tolerance for dietary MeHg exposure. If fish occupying low trophic levels are capable of surviving with high Hg body burdens, this tolerance has important implications for Hg exposure of organisms occupying higher trophic levels. Environ. Toxicol. Chem. © 2013 SETAC.
Environmental Toxicology and Chemistry 01/2013; · 2.81 Impact Factor
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ABSTRACT: Selenium (Se) is an essential micronutrient with a narrow therapeutic concentration range. The relative toxicity of Se increases as it is biotransformed into organic compounds, primarily selenomethionine (SeMet), within the aquatic food chain. Effects of aquatic Se contamination are well quantified for many freshwater fish and aquatic bird species, but impacts on amphibians are not well known. This study investigated the responses of larval Cope's gray tree frogs (Hyla chrysoscelis) fed a diet enriched with one of two concentrations of SeMet (50.1 and 489.9 μg Se g(-1) dw [low and high groups, respectively]) by way of a food-limited (ration) or ad libitum (ad lib) feeding regimen. The high dose caused 100 % mortality during the larval period independent of resource provision levels. Regardless of feeding regimen, the low dose decreased larval survival and successful metamorphosis relative to control treatments. The low dose also induced rear limb deformities in ≤73 % of individuals initiating metamorphosis. Providing low-dose food by way of a rationed feeding regimen decreased observed toxicity, likely because of decreased dietary exposure to SeMet relative to the low ad lib treatment. Individuals from the low ration treatment had decreased wet mass at initiation and completion of metamorphic climax (Gosner stages 42 through 46) compared with those from the control ad lib treatment, indicating that resource limitation combined with Se exposure might negatively affect energy stores after metamorphosis. However, lipid content analyses of recently metamorphosed individuals did not reveal any influence of treatment or resource provision on energy stored as lipids. The mean tissue Se concentration of individuals that received the low dose and completed metamorphosis was significantly greater than that of control ad lib or ration individuals at the same developmental stage. This study demonstrates that larval exposure to dietary SeMet can decrease growth and survival and induce deformities in a developing amphibian. Furthermore, retention of Se body burdens through metamorphosis suggests that surviving individuals can transport Se accumulated from contaminated aquatic environments into terrestrial food webs.
Archives of Environmental Contamination and Toxicology 12/2012; · 1.93 Impact Factor
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ABSTRACT: Polybrominated diphenyl ethers (PBDEs) are a bioaccumulative, persistent, and toxic class of flame retardants that can potentially impact turtles in natural habitats via exposure through maternal transfer. To simulate maternal transfer in the present study, PBDE congeners BDE-47 and BDE-99 were topically applied to the eggshell and were allowed to diffuse into the egg contents of the red-eared slider (Trachemys scripta elegans) and snapping turtle (Chelydra serpentina). Eggs were topically dosed over 8 d to achieve a target concentration of 40 ng/g in the egg contents. Transfer efficiency was higher for BDE-47 than for BDE-99 in the red-eared sliders (25.8 ± 1.9% vs 9.9 ± 1.1%) and snapping turtles (31.3 ± 1.6% vs 12.5 ± 1.4%), resulting in greater BDE-47 and lower BDE-99 egg content concentrations relative to the 40 ng/g target. However, only 25.8 and 31.3% of the total BDE-47 and 9.9 and 12.5% of the total BDE-99 dose applied could be accounted for in the red-eared slider and snapping turtle egg contents, respectively. Additionally, increased BDE-47 in red-eared slider egg contents dosed with only BDE-99 indicate that BDE-99 might have been debrominated to BDE-47. The efficacy of topical dosing for administering desired embryonic exposures is clearly affected by the chemical properties of the applied compounds and was more successful for BDE-47 in both species. Environ. Toxicol. Chem. © 2012 SETAC.
Environmental Toxicology and Chemistry 11/2012; · 2.81 Impact Factor
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ABSTRACT: Perchlorate is a surface and groundwater contaminant found in areas associated with munitions and rocket manufacturing and use. It is a thyroid-inhibiting compound, preventing uptake of iodide by the thyroid gland, ultimately reducing thyroid hormone production. As thyroid hormones influence metabolism, growth, and development, perchlorate exposure during the embryonic period may impact embryonic traits that ultimately influence hatchling performance. We topically exposed eggs of red-eared sliders (Trachemys scripta) and snapping turtles (Chelydra serpentina) to 200 and 177μg/g of perchlorate (as NaClO(4)), respectively, to determine impacts on glandular thyroxine concentrations, embryonic growth and development, and metabolic rates of hatchlings for a period of 2months post-hatching. In red-eared sliders, in ovo perchlorate exposure delayed hatching, increased external yolk size at hatching, increased hatchling mortality, and reduced total glandular thyroxine concentrations in hatchlings. In snapping turtles, hatching success and standard metabolic rates were reduced, liver and thyroid sizes were increased, and total glandular thyroxine concentrations in hatchlings were reduced after exposure to perchlorate. While both species were negatively affected by exposure, impacts on red-eared sliders were most severe, suggesting that the slider may be a more sensitive sentinel species for studying effects of perchlorate exposure to turtles.
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 07/2012; 156(3-4):166-70. · 2.62 Impact Factor
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ABSTRACT: Understanding the effects of chemical contaminants on natural populations is challenging, as multiple anthropogenic and natural stressors may individually and interactively influence responses. Population models can be used to evaluate the impacts of multiple stressors and to provide insight into population-level effects and/or data gaps. For amphibians with complex life cycles, population models may be useful in understanding impacts of stressors that are unique to the habitat type (aquatic, terrestrial) and that operate at different times in the life cycle. We investigated the population-level effects of aquatic contaminants (coal combustion residues, CCR) and terrestrial habitat loss on the eastern narrowmouth toad, Gastrophryne carolinensis, using existing empirical data that demonstrated negative reproductive and developmental effects of CCR and a series of population models that incorporated density dependence and environmental stochasticity. Results of deterministic models indicated that when terrestrial habitat was abundant, CCR-exposed toads had a larger population size compared to the reference population as a result of reduced density-dependent effects on larval survival. However, when stochasticity in the form of catastrophic reproductive failure was included, CCR-exposed toads were more susceptible to decline and extinction compared to toads from the reference populations. The results highlight the complexities involved in assessing the effects of anthropogenic factors on natural populations, especially for species that are exposed to multiple biotic and abiotic stressors during different periods in the life cycle.
Environmental Toxicology and Chemistry 09/2011; 30(12):2874-82. · 2.81 Impact Factor
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ABSTRACT: Selenium (Se) and vanadium (V) are contaminants commonly found in aquatic systems affected by wastes derived from fossil fuels. To examine their effects on a widely distributed species of amphibian, we exposed gray tree frogs (Hyla versicolor) to Se (as SeO₂) or V (as NaVO₃) in their diet from the early larval period to metamorphosis. Concentrations of Se in Se-enriched food were 1.0 (Se control), 7.5 (Se low), and 32.7 (Se high) μg/g dw. Concentrations of V in V-enriched food were 3.0 (V control), 132.1 (V low), and 485.7 (V high) μg/g dw. Although we observed bioaccumulation of both metals throughout the larval period, no effects on growth, survival, metabolic rate, or lipid content were observed. Se concentrations in tissues did not vary among life stages, neither in Se low nor Se high treatments, such that maximum accumulation had occurred by the mid-larval period. In addition, there was no evidence of depuration of Se in either the Se low or the Se high treatments during metamorphosis. A strikingly different pattern of accumulation and depuration occurred in V-exposed individuals. In treatments V low and V high, maximum body burdens occurred in "premetamorphs" (i.e., animals with developed forelimbs but in which tail resorption had not begun), whereas body burdens in animals having completed metamorphosis were much lower and similar to those in larvae. These results suggest that compared with Se-exposed animals, V-exposed animals were able to depurate a substantial amount of accumulated V during the metamorphic period. In an ecologic context, it appears that amphibians exposed to Se during the larval period may serve as a vector of the metal to terrestrial predators, yet potential transfer of accumulated V to predators would largely be restricted to the aquatic habitat.
Archives of Environmental Contamination and Toxicology 09/2010; 60(2):336-42. · 1.93 Impact Factor
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ABSTRACT: We conducted a factorial experiment to compare sublethal and lethal responses of juvenile snapping turtles exposed maternally and/or through the diet to polychlorinated biphenyls (PCBs) over 14 months posthatching. Maternal exposure did not affect embryonic development or hatching success. Thyrosomatic indices were not influenced by treatments, although hepatosomatic indices were lower in animals having been exposed to PCBs maternally relative to those having been exposed both maternally and via the diet. Dietary PCB exposure reduced metabolic rates of juveniles in two of three assays conducted. Approximately eight months after hatching, high rates of mortality began to emerge in individuals having been exposed maternally to PCBs, and mortality rate correlated with [PCB](total) in eggs. Prior to death, individuals that died experienced lower growth rates than those that survived, suggesting chronic effects prior to death. By 14 months posthatching, only 40% of juveniles derived from females in the contaminated area had survived, compared to 90% from the reference area. Such latent effects of maternally derived contaminants suggest that assessments of environmental impacts based upon shorter-term studies may provide very conservative estimates of the severity of effects, as they cannot capture responses that may emerge later in the life cycle.
Environmental Science and Technology 09/2009; 43(15):6052-7. · 5.23 Impact Factor
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ABSTRACT: Adult grass shrimp (Palaemonetes pugio) were exposed to either aqueous copper (ranging from 7.54 to 41.29 microg Cu(2+)/L) or cadmium (2.48- 6.55 microg Cd(2+)/L) for 14 days in laboratory experiments to quantify effects on survival and bioenergetic processes, including respiration, somatic growth, energy (lipid) storage, and food consumption. The lowest observed effect concentrations for mortality were 41.29 microg Cu(2+)/L or 6.55 microg Cd(2+)/L, expressed as free metal ion concentrations. Both copper and cadmium caused a decrease in respiration rate at concentrations of 7.54 to 41.29 microg Cu(2+)/L or 6.55 microg Cd(2+)/L. Exposure to copper (>or=27.03 microg Cu(2+)/L) resulted in negative somatic growth (i.e., weight loss). Cadmium exposure (6.17 microg Cd(2+)/L) caused a decrease in growth rate, relative to the control, but growth remained positive. Nonpolar lipid content and food consumption were not significantly affected by exposure to either copper or cadmium. Our results suggest that both copper and cadmium result in overall metabolic depression, decreasing energy allocation to both maintenance and production.
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 02/2009; 150(1):65-71. · 2.62 Impact Factor
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ABSTRACT: We conducted field studies over three years to assess body burdens and maternal transfer of polychlorinated biphenyls (PCBs) as well as indices of sexual dimorphism in snapping turtles (Chelydra serpentina) of the upper Hudson River (NY, USA.) We collected adult turtles in areas known to be contaminated with PCBs and in nearby reference areas for measurement of body size, precloacal length, and penis size. We analyzed PCB concentrations in eggs collected over three years and in whole blood from adults in one year. Total PCB concentrations (mean +/- standard error) in eggs were 2,800 +/- 520 and 59 +/- 5 ng/g wet weight in the contaminated area and the reference area, respectively. Eggs from the contaminated area were significantly enriched in tri-, penta-, and hepta-PCBs relative to the reference area. Blood from adults in the contaminated area averaged 475 +/- 200 and 125 +/- 34 ng/g wet weight for males and females, respectively. In the reference area, blood PCB concentrations were 7 +/- 3 and 4 +/- 1 ng/g wet weight for males and females, respectively. Significant positive relationships were found between carapace length and blood PCB concentration for both sexes in the contaminated area; however, only a marginal relationship was found between female carapace length and concentration of PCBs in their eggs. Our results suggest that PCB contamination of the upper Hudson River presents risks of establishing high body burdens and of maternal transfer of PCBs to eggs, although our measures of gross morphology revealed no discernable expression of abnormal sexual development or reproduction.
Environmental Toxicology and Chemistry 09/2008; 27(12):2565-74. · 2.81 Impact Factor
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ABSTRACT: In an 8-month laboratory experiment, Palaemonetes pugio (grass shrimp) were exposed to aqueous cadmium (free cadmium ion concentrations of 1.51 or 2.51 microg Cd(2+)/L) for an entire life cycle, from larva to reproductive adult and through to production of second-generation larva. Individual-level effects on survival, life stage duration, and reproduction were measured, and population growth was projected using two models: a stage-based matrix model and a z-transformed life cycle graph analysis. Adult survival was significantly reduced at 2.51 microg Cd(2+)/L, but cadmium exposure had no effects on survival or stage duration of embryos, larvae, or juveniles. Survival of second-generation larvae was unaffected by maternal exposure. Brood size was reduced by 27% at 1.51 microg Cd(2+)/L and by 36% at 2.51 microg Cd(2+)/L. The percent of females in the population that was gravid was approximately 50% lower at 2.51 microg Cd(2+)/L, compared to controls. Both population models projected a dose-dependent decrease in population growth rate (lambda), up to a 12% reduction at 2.51 microg Cd(2+)/L, which can be attributed mainly to contributions from reproductive effects. Elasticity analysis revealed that population growth rate was most sensitive to changes in survival of juveniles and adults. However, lethal effects of cadmium made only a small contribution to the effect on population growth rate. Even though both models project positive growth (lambda>1) of grass shrimp populations exposed to low concentrations of cadmium, the ability of populations to withstand predation pressure would be compromised.
Aquatic Toxicology 06/2008; 88(2):111-20. · 3.76 Impact Factor
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ABSTRACT: Coal combustion residues (CCRs), largely derived from coal-fired electrical generation, are rich in numerous trace elements that have the potential to induce sublethal effects including oxidative stress, alterations in antioxidant status and DNA single strand breaks (SSB). CCRs are frequently discharged into natural and man-made aquatic systems. As the effects of CCRs have received relatively little attention in estuarine systems, the estuarine grass shrimp, Palaemonetes pugio, was chosen for this study. Grass shrimp were exposed in the laboratory to CCR-enriched sediments and food over a full life cycle. Survival to metamorphosis was significantly reduced in CCR-exposed larvae (17+/-4 versus 70+/-13% in the controls) but not in the juveniles or adults. The COMET assay, a general but sensitive assay for genotoxicity, was used to quantify DNA SSB in the adults. Total antioxidant potential was examined to assess the overall antioxidant scavenging capacity of CCR-exposed and non-exposed adult grass shrimp. Grass shrimp exposed to CCR significantly accumulated selenium and cadmium compared to unexposed shrimp, although an inverse relationship was seen for mercury accumulation. Chronic CCR exposure caused DNA SSB in hepatopancreas cells, as evidenced by the significantly increased percent tail DNA, tail moment, and tail length as compared to reference shrimp. However, no significant difference was observed in total antioxidant potential. Our findings suggest that genotoxicity may be an important mode of toxicity of CCR, and that DNA SSB may serve as a useful biomarker of exposure and effect of this very common, complex waste stream.
Science of The Total Environment 03/2007; 373(1):420-30. · 3.29 Impact Factor
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ABSTRACT: We investigated the long-term effects of contaminants in sediment from Baltimore Harbor, MD, USA, on a burrowing amphipod (Leptocheirus plumulosus) via a full life-cycle laboratory exposure. Contaminants in the Baltimore Harbor sediment included PAHs (10,800 ng/g), PCBs (152 ng/g), and heavy metals (including As, Cd, Cu, Pb, Hg, Ni, and Zn). Exposures were initiated with neonate amphipods, placed in microcosms containing either contaminated or reference sediment, and were maintained for 42 days, allowing ample time for the initial cohort to mature and reproduce. At the end of the exposure period, the populations of amphipods were surveyed to ascertain the number and size of amphipods in each size class (neonate, juvenile, and adult), and bioenergetic measurements were performed on adults, including metabolic rate, lipid content, and fecundity. Contaminated sediment from Baltimore Harbor caused lower growth and reproductive rates; in Baltimore Harbor sediment, the average dry weight of amphipod offspring in each size class was significantly lower and there were less than one-third as many individuals in each size class, compared to reference sediment. By the end of the exposure, the total amphipod biomass in Baltimore Harbor sediment was less than one quarter of that in reference sediment. On average, gravid females in reference sediment produced at least twice as many viable offspring as those in contaminated sediment. Adult male amphipods in Baltimore Harbor sediment possessed significantly lower lipid concentrations. Lipid content in neonates also appeared to be negatively affected by parental exposure to contaminants. Metabolic rate was elevated in adult amphipods exposed to Baltimore Harbor sediment. Overall, the results suggest that contaminated sediment conditions in the urban estuary may chronically affect L. plumulosus by diverting energy from production to maintenance pathways, resulting in slower growth and reduced fecundity, and ultimately leading to retarded population growth rates. The results of this study reinforce the need for long-term toxicological exposures to reveal chronic effects.
Marine Environmental Research 09/2006; 62(2):116-30. · 2.28 Impact Factor
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ABSTRACT: Selenium (Se) is embryotoxic in many oviparous vertebrates, but little is known about maternal transfer of Se and its impact in reptiles. Over a four-year period, we collected three clutches of eggs of the American alligator (Alligator mississippiensis) from a single nest at a site contaminated with Se and compared egg and hatchling Se concentrations and clutch viability from this nest to nests downstream from the contaminated site (two clutches from two nests) and at a reference site (two clutches from two nests). Eggs and hatchlings from the nest at the Se-contaminated site and downstream nests had elevated Se concentrations (2.1-7.8 ppm) and lower viability (30-54%) compared to reference nests (1.4-2.3 ppm and 67-74% viability), but Se concentrations did not exceed reproductive toxicity thresholds established for other oviparous vertebrates. Selenium concentrations were higher in chorioallantoic membranes of eggs from Se-contaminated sites, suggesting that this tissue may be useful as a nondestructive index of Se exposure for embryos of A. mississippiensis. Examination of these data suggests that further studies on uptake, accumulation, and reproductive success of crocodilian embryos exposed to excessive Se are warranted.
Environmental Toxicology and Chemistry 09/2004; 23(8):1969-72. · 2.81 Impact Factor
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Christopher L Rowe
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ABSTRACT: Hatchling Cyprinodon variegatus were raised in the presence or absence of sediments contaminated with mixed trace elements to examine lethal and sublethal bioenergetic effects (metabolic rate, lipid storage, growth, reproduction) over a full life cycle (>1 year). Contaminated sediments were derived from a site receiving coal combustion residues (CCR) and were elevated in numerous trace elements including Al, As, Ba, Cd, Cu, Se, and V. Exposures were conducted at two levels of salinity (5 and 36 ppt) to examine the potential interaction of this variable with contaminants. Salinity had no effect on responses measured. Over the course of the study, fish exposed to contaminated sediment accumulated several CCR-related trace elements, including As, Cd, Se, and V. There were no differences in fish survival for contaminated sediment treatments and uncontaminated sediment treatments, nor were there differences in metabolic expenditures. However, growth, male condition factor, and storage lipid content in females were reduced due to contaminant exposure. No significant effects on fecundity or the proportion of females that were gravid at the end of the study were observed, yet females raised under control conditions produced 12% larger eggs than did females raised on contaminated sediments. During the presumably most-sensitive early life stages, individuals were not noticeably affected by contaminants, but rather the effects of exposure became apparent later in life. Because many species inhabit contaminated areas for long periods of time, often encompassing the entire life cycle, exposures focused only on specific life stages may substantially underestimate the overall responses elicited by individuals.
Ecotoxicology and Environmental Safety 02/2003; 54(2):229-39. · 2.29 Impact Factor
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ABSTRACT: We provide an overview of research related to environmental effects of disposal of coal combustion residues (CCR) in sites in the United States. Our focus is on aspects of CCR that have the potential to negatively influence aquatic organisms and the health of aquatic ecosystems. We identify major issues of concern, as well as areas in need of further investigation. Intentional or accidental release of CCR into aquatic systems has generally been associated with deleterious environmental effects. A large number of metals and trace elements are present in CCR, some of which are rapidly accumulated to high concentrations by aquatic organisms. Moreover, a variety of biological responses have been observed in organisms following exposure to and accumulation of CCR-related contaminants. In some vertebrates and invertebrates, CCR exposure has led to numerous histopathological, behavioral, and physiological (reproductive, energetic, and endocrinological) effects. Fish kills and extirpation of some fish species have been associated with CCR release, as have indirect effects on survival and growth of aquatic animals mediated by changes in resource abundance or quality. Recovery of CCR-impacted sites can be extremely slow due to continued cycling of contaminants within the system, even in sites that only received CCR effluents for short periods of time. The literature synthesis reveals important considerations for future investigations of CCR-impacted sites. Many studies have examined biological responses to CCR with respect to Se concentrations and accumulation because of teratogenic and reproductively toxic effects known to be associated with this element. However, the complex mixture of metals and trace elements characteristic of CCR suggests that biological assessments of many CCR-contaminated habitats should examine a variety of inorganic compounds in sediments, water, and tissues before causation can be linked to individual CCR components. Most evaluations of effects of CCR in aquatic environments have focused on lentic systems and the populations of animals occupying them. Much less is known about CCR effects in lotic systems, in which the contaminants may be transported downstream, diluted or concentrated in downstream areas, and accumulated by more transient species. Although some research has examined accumulation and effects of contaminants on terrestrial and avian species that visit CCR-impacted aquatic sites, more extensive research is also needed in this area. Effects in terrestrial or semiaquatic species range from accumulation and maternal transfer of elements to complete recruitment failure, suggesting that CCR effects need to be examined both within and outside of the aquatic habitats into which CCR is released. Requiring special attention are waterfowl and amphibians that use CCR-contaminated sites during specific seasons or life stages and are highly dependent on aquatic habitat quality during those periods. Whether accidentally discharged into natural aquatic systems or present in impoundments that attract wildlife, CCR appears to present significant risks to aquatic and semiaquatic organisms. Effects may be as subtle as changes in physiology or as drastic as extirpation of entire populations. When examined as a whole, research on responses of aquatic organisms to CCR suggests that reducing the use of disposal methods that include an aquatic slurry phase may alleviate some environmental risks associated with the waste products.
Environmental Monitoring and Assessment 01/2003; 80(3):207-76. · 1.40 Impact Factor
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Christopher L Rowe
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ABSTRACT: The estuarine shrimp Palaemonetes pugio and P. vulgaris co-occur across a broad range in salinity. Field surveys and laboratory lethality tests suggest that low salinity conditions favor P. pugio over P. vulgaris. This study compared energetic expenditures across a range in salinity (0.5-35 ppt) to test the hypothesis that P. pugio experiences lower maintenance-energy requirements than P. vulgaris in low-salinity habitats. Standard metabolic rate (SMR) was measured as the minimum oxygen consumption rate at 25 degrees C to estimate daily maintenance-energy expenditure. SMR was greatest at 0.5 and least at 10 ppt (irrespective of species), and greater for P. vulgaris than for P. pugio. At low salinity (1.5-3 ppt), SMR was lower for P. pugio than for P. vulgaris. Energy expenditure did not coincide with the pattern predicted based upon osmoregulatory costs alone; no reduction was observed near the reported hemolymph concentration for P. vulgaris, although a minimum was observed near the hemolymph isoionic concentration for P. pugio. A local minimum in SMR by P. pugio between 1.5 and 3 ppt contrasted with relatively high SMR of P. vulgaris across this range. It appears that low-salinity habitats are energetically more favorable for P. pugio than for P. vulgaris. The results suggest an adaptive mechanism allowing P. pugio to occupy environments that present its competitor, P. vulgaris, with greater energetic challenges. While long-term exposure to very low salinity may be detrimental to both species, energetic traits of P. pugio may confer it with greater success than P. vulgaris in habitats in which salinity periodically fluctuates to low values.
Comparative Biochemistry and Physiology - Part A Molecular & Integrative Physiology 07/2002; 132(2):341-51. · 2.23 Impact Factor
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ABSTRACT: Whereas ecological assessments of contaminants are concerned with populations and higher levels of organization, most mechanistic work in toxicology is directed at effects on individuals and their parts. We propose that studies based on individuals can be useful in ecological analysis of polluted systems when based on the concepts of resource allocation-based life history analysis. At the heart of the resource allocation approach is the concept of operative environments of individuals (i.e., environmental factors influencing birth, death, or migration). Contaminants can have strong influences on operative environments, modifying resource allocation strategies that reflect changes in energy assimilation and demands. By examining contaminant-induced responses of individuals from the perspective of changing operative environments, individual-based changes and population dynamics can be addressed in an ecologically rigorous manner.
Environmental Toxicology and Chemistry 07/2001; 20(8):1698 - 1703. · 2.81 Impact Factor
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ABSTRACT: Trace element concentrations in banded water snakes, Nerodia fasciata, and representative prey items from a site polluted by coal combustion wastes were compared with concentrations in conspecifics from a nearby reference site. Water snakes accumulated high concentrations of trace elements, especially arsenic (As) and selenium (Se), in the polluted habitat. In addition to being exposed to contaminants in water and sediments, snakes in the polluted site are exposed to contaminants by ingesting prey items that have elevated whole-body concentrations of trace elements, including As, cadmium (Cd), and Se. Snakes from the polluted site exhibited mean standard metabolic rates (SMR) 32% higher than snakes from the reference site. As a result, snakes from the polluted site appear to have elevated allocation of energy to maintenance and theoretically should have less energy available for growth, reproduction, and storage. Our findings are consistent with physiological responses recently documented in other organisms from the polluted site. We hypothesize that long-term exposure to coal ash–derived trace elements and the resultant accumulation of some elements are responsible for observed increases in SMR.
Environmental Toxicology and Chemistry 05/1999; 18(6):1258 - 1263. · 2.81 Impact Factor
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ABSTRACT: Snapping turtle (Chelydra serpentina) eggs were exposed to two concentrations of chemically- or physically-dispersed water accommodated fractions of weathered Arabian light crude oil (Low = 0.5 and High = 10 g oil/L water). Solutions were passed through nest substrate to simulate alterations in composition during percolation to egg depth. Hatchlings were raised for 13 months during which numerous endpoints were measured. Prior to percolation, total PAH (“tPAH”; the sum of 52 PAHs measured) in physically-dispersed oil fractions were similar (High, 43; Low 67 mg/L). Following percolation, tPAH was also similar in physically-dispersed fractions (High, 14; Low 24 mg/L). Addition of dispersant increased tPAH prior to percolation in the High treatment (302 mg/L) relative to Low (13 mg/L), but percolation resulted in nearly equal concentrations in both treatments (High, 30; Low, 22 mg/L) due to physical trapping of dispersed oil by the nest substrate. In both chemically- and physically-dispersed fractions, percolation reduced low molecular weight (MW) compounds such that embryos were exposed to primarily mid- to high MW compounds. Total PAH in eggs differed 15-fold between the chemically-dispersed High and physically-dispersed High treatments (560 and 36 µg/kg respectively), the former characterized by higher MW compounds than the latter. While eggs accumulated up to 560 µg/kg tPAH, we observed no effects on hatching success or hatchling/juvenile traits (DNA integrity, survival, growth, metabolism, energy storage, or behavior), our results demonstrate that PAH profiles are altered during percolation, suggesting that experiments with subsurface organisms should be designed to account for compositional changes that occur as the solutions percolate through the substrate.
Science of The Total Environment.
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ABSTRACT: Palaemonetes pugio exposed to copper (9 or 26 μg Cu2+/L) for a full life cycle were unable to produce viable embryos, precluding completion of the life cycle, despite no lethal effects on larval, juvenile, or adult life stages. Exposure to copper also resulted in a significant delay in larval development. When adults raised in copper were transferred to control seawater, they produced viable embryos, but larval output per clutch was reduced by 43% compared to clutches from females that had never been exposed to copper, suggesting reduced energetic allocation to reproduction. In acute exposures, adults exposed to copper for as little as three days were unable to produce viable embryos. Furthermore, exposure of control embryos to copper reduced hatching success by 74%. The reduction in hatching success and energetic allocation to reproduction are unlikely to be completely responsible for the lack of larval production observed in pre-spawning exposures to copper, suggesting that copper may also inhibit processes before or during spawning and fertilization.
Marine Environmental Research.
