Article

Correlation and toxicological inference of trace elements in tissues from stranded and free-ranging bottlenose dolphins (Tursiops truncatus)

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Abstract

The significance of metal concentrations in marine mammals is not well understood and relating concentrations between stranded and free-ranging populations has been difficult. In order to predict liver concentrations in free-ranging dolphins, we examined concentrations of trace elements (Al, As, Ba, Be, Cd, Co, Cu, Fe, Li, Mn, Ni, Pb, Sb, Se, Sn, total Hg (THg), V, Zn) in skin and liver of stranded bottlenose dolphins (Tursiops truncatus) from the South Carolina (SC) coast and the Indian River Lagoon, Florida (FL) during 2000-2008. Significantly higher concentrations of Zn, Fe, Se, Al, Cu and THg were found in skin while liver exhibited significantly higher Cu, Fe, Mn and THg concentrations for both study sites. Mean skin concentrations of Cu and Mn were significantly higher in SC dolphins while higher concentrations of THg and V were found in FL dolphins. In addition, liver tissues in SC dolphins exhibited significantly higher As concentrations while higher Fe, Pb, Se, THg, and V levels were found in FL dolphins. Two elements (Cu and THg) showed significant age-related correlations with skin concentration while five elements (Cu, Se, THg, Zn and V) showed age-related correlations with liver concentrations. Geographic location influenced age-related accumulation of several trace elements and age-related accumulation of THg in hepatic tissue was observed for both sites to have the highest correlations (r² = 0.90SC; r² = 0.69FL). Mean THg concentration in liver was about 10 times higher in FL dolphins (330 μg g⁻¹ dw) than those samples from SC dolphins (34.3 μg g⁻¹ dw). The mean molar ratio of Hg to Se was 0.93 ± 0.32 and 1.08 ± 0.38 for SC and FL dolphins, respectively. However, the Hg:Se ratio varied with age as much lower ratios (0.2-0.4) were found in younger animals. Of the 18 measured elements, only THg was significantly correlated in skin and liver of stranded dolphins and skin of free-ranging dolphins from both sites suggesting that skin may be useful in predicting Hg concentrations in liver tissue of free-ranging dolphins. Results indicate that 33% of the stranded and 15% of the free-ranging dolphins from FL exceed the minimum 100 μg g⁻¹ wet weight (ww) (~ 400 dw) Hg threshold for hepatic damage while none from SC reached this level. Hepatic concentrations of As in SC dolphins and V in FL dolphins were also highly correlated with skin concentrations which may have some regional specificity predictive value. The present study provides the first application of trace element concentrations derived from stranded bottlenose dolphins to predict liver concentrations in free-ranging populations.

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... Accumulation of cadmium has been reported primarily in liver, kidney, and muscle tissue from stranded dolphins considering age, sex, tissue type, and region (Stavros et al., 2011). It is important to assess cadmium and other trace elements in free-ranging animals to develop baselines and subsequently criteria for prediction of toxicological risk. ...
... It is important to assess cadmium and other trace elements in free-ranging animals to develop baselines and subsequently criteria for prediction of toxicological risk. Studies have established that skin can be used as a non-invasive sampling method to evaluate trace element levels in cetaceans (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. ...
... Honda and Tatsukawa (1983) explain that cadmium builds up rapidly in dolphins from birth to a maximum concentration of 20 to 30 μg/g ww, which is maintained for the lifespan. However, Stavros et al. (2011) found no significant differences in cadmium concentrations in bottlenose dolphins by age. This study found that cadmium concentrations were significantly higher in the skin of adult male sperm whales compared to subadult males. ...
... Contrary to the internal organs, epidermis tissues can be sampled using a biopsy darting, providing a high number of samples from free-ranging, healthy individuals in the wild populations (Lambertsen et al. 1994;Barrett-Lennard et al. 1996). Previous studies showed positive correlations of Hg concentrations between the epidermis and liver tissues in Dall's porpoises (Phocoenoides dalli) (Yang et al. 2002), striped dolphins (Stenella coeruleoalba) (Monaci et al. 1998), and bottlenose dolphins (Tursiops truncatus) (Stavros et al. 2011). These studies indicated that the epidermis can be used as a surrogate sampling tissue to monitor hepatic Hg concentrations. ...
... The significant positive correlations (p b 0.05) of Hg and As concentrations between the epidermis and liver samples suggest that cutaneous Hg and As concentrations could be used to assess hepatic Hg and As concentrations in S. chinensis. The positive correlations of Hg concentrations between the epidermis and liver established here were consistent with previous studies on cetacean species including Dall's porpoise (Yang et al. 2002), striped dolphin (Monaci et al. 1998) or bottlenose dolphin (Stavros et al. 2011). For As concentrations, similarly positive correlations between the epidermis and liver were established in bottlenose dolphins from South Carolina coast (Stavros et al. 2011). ...
... The positive correlations of Hg concentrations between the epidermis and liver established here were consistent with previous studies on cetacean species including Dall's porpoise (Yang et al. 2002), striped dolphin (Monaci et al. 1998) or bottlenose dolphin (Stavros et al. 2011). For As concentrations, similarly positive correlations between the epidermis and liver were established in bottlenose dolphins from South Carolina coast (Stavros et al. 2011). The positive relationships for Hg and As are likely due to the fact that these elements are bioaccumulative both in the internal tissues and in the epidermis. ...
Article
Trace element accumulation in the epidermis of cetaceans has been less studied. This study explored the feasibility of using epidermis as a surrogate tissue to evaluate internal contaminant burdens in Indo-Pacific humpback dolphin (Sousa chinensis). Eleven trace elements were analyzed in the epidermis, muscle and liver tissues from 46 individuals of dolphins stranded along the Pearl River Estuary (PRE) coast between 2007 and 2013. Trace elemental concentrations varied among the three tissues, generally with the highest concentrations found in liver tissues and lowest in the epidermis (except Zn, As, and Pb). Zn concentration in the epidermis was the highest among all tissues, indicating that Zn could be an important element for the epidermis physiology. High concentrations of Hg and Cr in liver were likely due to an excessive intake by dolphins which consumed high Hg and Cr contaminated fishes in the PRE. Hg concentrations in epidermis and muscle tissues were significantly higher in the females than in males. Concentrations of V and Pb in liver, Se and Cd in both muscle and liver, and As and Hg in all tissue samples showed significantly positive relationships with body length. Hepatic Cu concentrations were significantly negatively correlated with the body length. Hg and As concentrations in epidermis showed significantly positive correlations with those in liver tissues. Thus this study proposed that epidermis could be used as a non-invasive monitoring tissue to evaluate Hg and As bioaccumulation in internal tissues of Indo-Pacific humpback dolphins populations.
... Cetacean skin biopsies are recommended as a non-invasive tool for assessing the eco-toxicological risk of populations and to conduct long-term environmental monitoring programs (Bryan et al., 2007;Fossi et al., 2000;Savery et al., 2013a;Stavros et al., 2007Stavros et al., , 2011. Measuring Hg in the skin of piscivorous homeotherms is important to evaluate the exposure routes in marine environments and to assess the potential for toxicity to biota (Miller et al., 2011;Wöshner et al., 2008). ...
... Although there are several reports on the elemental concentrations in the epidermis of cetaceans (Aubail et al., 2013;Dehn et al., 2006;Kunito et al., 2002;O'Hara et al., 2008;Savery et al., 2013bSavery et al., , 2014Yang et al., 2002), there is little information on inter-tissue correlation or association between the heavy metal concentrations in such organs and those in the internal tissues. For Hg, several studies indicate that there is a correlation between the Hg concentration in skin and liver in odontocetes, such as Dall's porpoise (Phocoenoides dalli) (Yang et al., 2002), the harbor porpoise (Phocoena phocoena), the common dolphin (Delphinus delphis) (Aubail et al., 2013), the striped dolphin (Stenella coeruleoalba) (Aubail et al., 2013;Monaci et al., 1998;Borrell et al., 2015), the bottlenose dolphin (Tursiops truncatus) (Stavros et al., 2011;Aubail et al., 2013), and mysticetes including the bowhead whale (Balaena mysticetus) . Moreover, O'Hara et al. (2008) found that the epidermal Hg concentration was predictive of the blubber, hepatic and muscle tissue concentrations in bowhead whales. ...
... For six specimens, two samples of muscle were processed, extracted from the central and posterior body region, and the elemental concentrations measured were averaged for further correlations. (Caurant et al., 1996;Lockhart et al., 2005;Stavros et al., 2011;Wagemann et al., 1996). Specifically, Hg tends to accumulate in the liver, an organ that metabolizes nutrients and essential elements and removes non-essential elements, compounds and toxins from the bloodstream in mammals (Augier et al., 1993;Frodello et al., 2000). ...
... In our study, As concentrations were within the range of values reported for various stranded marine mammals. For instance, California sea lions from southern California (Harper et al., 2007) and bottlenose dolphins from south Carolina and Florida waters (Stavros et al., 2011). The bottlenose dolphins from this latter study also exhibited same range of V levels in their livers compared to porpoises stranded in our study. ...
... Moreover, the present 85 hepatic V levels were in the same order of magnitude compared to those reported in other marine mammals such as, Beluga whales (Mackey et al., 1996), various pinnipeds (Saeki et al., 1999) and Caspian seals (Anan et al., 2002). An increase in the concentrations of V with age has been reported in several species of marine mammals and in addition V levels were correlated with Hg levels in the liver (Mackey et al., 1996;Saeki et al., 1999;Anan et al., 2002;Ikemoto et al., 2004;Stavros et al., 2011). Similarly, adult porpoises showed significant higher levels of V in livers compared to juveniles and a significant correlation was found between hepatic V and Hg accumulation (table 3.3). ...
... Hence, seal blood appeared to be useful to monitor the influence of different conditions or contaminations in a specific area on marine mammals. In order to evaluate the use of biopsy samples as non-destructive tool for assessing trace element concentrations in marine mammals, more recent studies have attempted to predict liver concentrations in free ranging animals by examining concentrations of trace elements in skin, blubber, liver and kidney of stranded animals (Stavros et al., 2011;Aubail et al., 2013). The results of both studies showed that this method can only be used to investigate Hg bioaccumulation in internal tissues of cetaceans. ...
Article
Full-text available
The North Sea is heavily impacted by human activities such as overfishing and pollution. Due to their position as top predators in the ocean, marine mammals are becoming increasingly affected by anthropogenic activities. The large-scale surveys SCANS in 1994 and SCANS II in 2005 that were held in the North Sea to estimate the abundance of small cetaceans highlighted a major shift in the distribution of harbour porpoises (Phocoena phocoena) from the northern parts of the North Sea to its eastern parts. Alongside, over the past few decades harbour porpoises stranding has increased in the southern North Sea particularly along the French and Belgian coastal waters. Since the contaminant exposure presents, among others, a potential threat to harbour porpoises inhabiting the North Sea, the first objective of the present study was to assess the contamination status of this species in the southern North Sea. On the other hand, the distribution and abundance of marine mammals is expected to follow the distribution of their main prey species. Hence, the second objective of this study was to investigate whether the changes in the distribution of porpoises in the southern North Sea may be a result of the changes in prey availability. Moreover, the third objective was to evaluate the interest of combining three methods to investigate the diet of harbour porpoises: stomach contents, stable isotopes (carbon and nitrogen) and fatty acids analyses. First, the contamination status was evaluated through the determination of two components of chemical contaminants (metals and persistent organic pollutants) in tissues of harbour porpoises stranded along the southern North Sea between 2006 and 2013. Several chemical contaminants presented higher concentrations in diseased animals compared to healthy animals. In addition, some metallic contaminants showed bioaccumulation with age. Comparison with previous study suggests that the population status of harbour porpoises in term of chemical concentration has been stable from 1994 to 2013. This work suggested that the increase in the number of stranded individuals is not related to the decline in the quality of the environment. Secondly, the shift in the abundance of harbour porpoises was evaluated and interpreted in the light of prey species abundance. Three techniques were used in order to determine the diet of porpoises. Results highlighted the presence of gobies, whiting, sandeel, sprat, trisopterus sp., herring and sardine as potential preys. The shift of the abundance of porpoises form the northern parts of the North Sea to its southern parts was attributed to the sandeel abundance decline in the northern parts of the North Sea along with the re-invasion of the southern North Sea by the sardine species, probably in response to climate change. Finally, the value of a multi-approach dietary analysis was evaluated. Besides overcoming the limitations of each method, combining different techniques that integrate diet over days and weeks allowed gaining more complete understanding of harbour porpoise’s diet.
... Many toxicological studies have focused on the evaluation of pollutant burdens of bottlenose dolphin populations (e.g. Lavery et al., 2008;Stavros et al., 2011;Bilandzic et al., 2012;Méndez-Fernandez et al., 2014;García-Alvarez et al., 2015). However, information regarding the concentration of trace elements in bottlenose dolphins in the Atlantic coast of Iberia is scarce and based on very small sample sizes (n = 2, Carvalho et al., 2002;n = 8, Méndez-Fernandez et al., 2014). ...
... In general, bottlenose dolphins stranded in continental Portugal showed, for most of the trace element studied, similar concentrations to those previously reported in the Atlantic Ocean, namely Portugal (Carvalho et al., 2002), the north-western coast of Iberia (Méndez-Fernandez et al., 2014), Britain (e.g. Law et al., 1992), France (Lahaye et al., 2006), the eastern coast of the USA (Stavros et al., 2011) or Brazil (Lemos et al., 2013). The most noteworthy exception was related with the higher levels of Hg obtained in the three tissues analysed in the present study, compared to elsewhere in the Atlantic Ocean (see Table 4). ...
... Higher Hg values had also been detected in the past in bottlenose dolphins from Florida (Rawson et al., 1993), although recent analyses showed much lower Hg levels (Stavros et al., 2011). Table 1 Detection limits (ng·ml −1 ) and element concentrations (μg·g −1 ) in the standard reference material DORM-2 and DOLT-3 determined by inductively coupled mass spectrometry (ICP-MS). ...
Article
Both the conservation status of bottlenose dolphins (Tursiops truncatus) (Habitats Directive 92/43/CEE, Annex II) and the Marine Strategy Framework Directive demand for data on their ecology and anthropogenic threats. To evaluate the bottlenose dolphin's toxicological status in continental Portugal, several trace elements (As, Cd, Cu, Hg, Mn, Ni, Pb, Se, Zn) were determined in 25 stranded individuals. The potential effect of sex, body length and stranding location on trace element concentrations was analysed. In the present study, bottlenose dolphins presented high mercury levels, only exceeded by animals from the Mediterranean and Adriatic seas. Only essential elements were influenced by dolphin sex, whereas Cd, Hg and Pb bioaccumulated in larger dolphins, and hepatic Hg and Cd concentrations were higher in the northwest coast of continental Portugal. The location effect may relate to variations in bottlenose diet and trace element availability, according to the proximity to anthropogenic sources in the Atlantic Iberian coast.
... In addition, internal physiological state (i.e., sexual maturation, size, and molting) were also found to affect body bioaccumulation (Méndez-Fernandez et al. 2014;Wagemann and Kozlowska 2005). Hereafter, monitoring trace element concentrations could facilitate the identification of toxic risks Responsible Editor: Philippe Garrigues in wild populations (Stavros et al. 2011), offering key evidence for progress of conservation management plans. Indeed, such interest is outstanding by increasing number of eco-toxicological studies (e.g., Yang et al. 2002;Aubail et al. 2013;Borrell et al. 2015;Cáceres-Saez et al. 2015;Savery et al. 2014;Zhang et al. 2017;Xiong et al. 2019). ...
... Particularly, skin biopsies have been found to be an effective tool to quantify and monitor levels of pollutants in cetaceans (Monaci et al. 1998;Wagemann and Kozlowska 2005;Wöshner et al. 2008). For this purpose, an important feature is to appraise the skin-to-internal body tissue relationships among those elemental concentrations measured since some authors have indicated that skin can be used as a proxy of heavy metals in body tissues of odontocetes and mysticetes (Aubail et al. 2013;Borrell et al. 2015;Kunito et al. 2002;Monaci et al. 1998;Stavros et al. 2011;Wöshner et al. 2008;Yang et al. 2002). Accordingly, remote biopsies on board outstand as a non-invasive technique to investigate pollution exposure and bioaccumulation in free-ranging populations' overtime and get insight their eco-toxicological risk (Savery et al. 2013(Savery et al. , 2014(Savery et al. , 2015Wise et al. 2011). ...
... The analytical uncertainty is reported after the plus minus (±) sign Environ Sci Pollut Res skin has been shown to be a target organ for Se deposition (Savery et al. 2013;Stavros et al. 2011;Yang et al. 2002). As well as known in humans (Sengupta et al. 2010), Se plays a vital role in wound healing, dermal cell proliferation, and collagen deposition at injuries of the skin (Paludan-Müller et al. 1993). ...
Article
Full-text available
On a global scale, cetaceans are recognized well indicators of marine ecosystem health. Trace elements accumulate in their bodies and potentially constitute a toxicological threat. Here, the concentrations of essential Se; unknown physiological elements Br, Rb, Cs, Ni, and Sr; and pollutants arsenic, Cd, Hg, and Ag were assessed in the skin of false killer whales (Pseudorca crassidens) stranded at Estrecho de Magallanes, South America, and next, tissue comparisons and relationships between elemental concentrations in the skin and internal tissues (liver, kidney, spleen, lung, skeletal muscle, and testis) were assessed. Results showed elemental concentration variations among tissues. Selenium concentration was found to be higher in the liver 398 (75) μg g−1 dry weight (DW) (standard deviation in parenthesis), followed by skin. Rubidium and Br concentrations were higher in testis 7.92 (0.42) and 99.1 (5.4) μg g−1 DW, respectively, and Cs in muscle 0.36 (0.12) μg g−1 DW, while Ni concentrations range (<0.05–0.91 μg g−1 DW) did not show differences among tissues. Cadmium and arsenic were found to be higher in kidneys, 71.2 (17.6) and 2.54 (1.77) μg g−1 DW, respectively, while Hg was highest in the liver 1068 (234) μg g−1 DW. Concerning inter-tissue relationships, a positive skin-to-kidney and skin-to-muscle correlations were observed for Cs concentrations, and also Hg showed positive skin-to-spleen, skin-to-kidney, and skin-to-testis correlations, which support its use as potential offshore marine biomonitor.
... Elements are obtained during digestion and absorbed from the gastrointestinal tract that enters the systemic circulation of whole body (Honda et al. 1982;Andre et al. 1990;Augier et al. 1993). In cetaceans, trace elements can be uptaken via alveolar gas exchange in the lungs to blood and by absorption through the skin (Augier et al. 1993;Bryan et al. 2007;Stavros et al. 2011;Savery et al. 2013bSavery et al. , 2014. Dermal contact is a feasible means of exposure since cetacean skin has a fragile superficial layer (not fully cornified) and dense sub-epidermic vascular system (Augier et al. 1993). ...
... The skin of cetaceans has been increasingly used in studies focused on population structure and feeding ecology, being considered a useful tool in environmental monitoring programs (Monaci et al. 1998;Fossi et al. 2000;Kunito et al. 2002;Savery et al. 2013aSavery et al. , b, 2014. During the last two decades, skin biopsy samples have become suitable tissues to assess concentrations and type of pollutants, given the need of minimally invasive sampling procedures for living mammals in the marine environment (Fossi et al. 2000;Bryan et al. 2007;Stavros et al. 2007Stavros et al. , 2011Savery et al. 2013aSavery et al. , b, 2014. Nevertheless, many studies have been performed on the bioaccumulation of heavy metals and other trace elements in the skin from stranded, by-caught or even hunted animals (Fujise et al. 1988;Carvalho et al. 2002;Roditi-Elasar et al. 2003;O'Hara et al. 2008;Aubail et al. 2013;Borrell et al. 2015). ...
... Sampling during postmortem examinations has become a significant source of information for diverse species. Reliable results have been obtained from skin analyses, provided it is collected from a freshly dead animal in good body condition (Bryan et al. 2007;Stavros et al. 2007Stavros et al. , 2011. ...
Article
Full-text available
The skin of cetaceans is the most accessible tissue, and its sampling has been proposed as a noninvasive method to evaluate trace element concentrations in free-ranging populations. In the present work, concentrations of essential (Cl, Na, K, Mg, Fe, Zn, Mn and Co), nonessential (As and Ag), and of unknown essentiality (Br, Rb and Cs) elements were determined in the skin from nine by-caught Commerson’s dolphins (Cephalorhynchus commersonii) from Tierra del Fuego, Argentina. Skin correlations with internal tissues—lung, liver, kidney and muscle—were assessed to evaluate how the skin represents internal element concentration for monitoring purposes. Elemental contents were analyzed by instrumental neutron activation analysis (INAA). Regarding tissue distribution, skin had the highest concentration of Zn being two orders of magnitude higher than internal tissues, while other elements such as Co and Rb had similar concentrations among tissues. High mean concentrations of Cl, Na, Mg, Br and Mn were observed in the lung and liver. Our results support the use of skin to evaluate Fe, Br and Rb concentrations in internal tissues for biomonitoring purposes; however, other elements did not show significant skin-to-tissue correlations. Overall, toxic element levels were far below concentrations found to cause harm in marine vertebrates. This study provided baseline data on elemental concentrations in tissues of Commerson’s dolphins in subantarctic waters from the South Atlantic Ocean.
... In an epidemiological study, Stavros et al. (2011) found average aluminium levels in skin of stranded bottlenose dolphins (10.5 ± 10.2 and 21.2 ± 22.4 mg/kg dry weight) to be significantly (P < 0.001) higher than concentrations in skin of free-ranging bottlenose dolphins (3.79 ± 5.58 and 9.00 ± 22.6 mg/kg dry weight) at two east coast USA sampling sites. It should be noted that some free-ranging dolphins had aluminium levels as high or exceeding those of stranded animals. ...
... In Stavros et al.'s comparison of metal levels in skin of stranded (3.81 ± 1.51 and 2.67 ± 0.72 mg/kg dry weight) and free-ranging bottlenose dolphins (1.57 ± 0.34 and 1.44 ± 0.30 mg/kg dry weight), copper was found to be highly significantly (P < 0.001) elevated in stranded dolphins (Stavros et al., 2011). Again, it should be noted that stranded animals were not examined for infectious disease in this study. ...
... Harper et al. (2007) compared hepatic metal levels (arsenic, cadmium, copper, iron, mercury, lead, manganese, molybdenum and zinc) in diseased Californian sea lions and also found hepatic zinc (and molybdenum) to be elevated in sea lions with infectious disease compared to unaffected individuals (103.2 ± 30.2 vs. 96.6 ± 33.6 mg/kg wet weight) (Table 10). Stavros et al. (2011) compared zinc levels in skin of stranded bottlenose dolphins with those in free-ranging individuals and found stranded dolphins to have significantly higher zinc concentrations in the skin than free-ranging dolphins. While zinc levels were elevated at both of two sampling sites on the U.S. east coast, the difference was only significant at one of the two sites (731 ± 181 vs. 602 ± 209 mg/kg dry weight) due to high variability at the other site (976 ± 1108 vs. 685 ± 234). ...
... Body tissues are specific in their ability to accumulate Hg and transfer to other tissues, which involves different Hg species (Wagemann et al., 1998). Mercury in skeletal muscle is largely accumulated in the form of MeHg which is thought to have a half-life about 1000 days in mammals (Stavros et al., 2011). The MeHg accumulation in muscle likely due to its high affinity for sulfhydryl groups associated with the thiol-containing amino acids in the myoglobin proteins (Castellini et al., 2012). ...
... Furthermore, higher Hg accumulation has been observed in diseased animals suggesting they lack ability to detoxify organic Hg efficiently as healthy animals (Siebert et al., 1999). Chronic lowlevel Hg exposure could suppress immune and endocrine system of animals, suggesting that Hg exposure has immune-modulatory effects accompanied by an increase in diseases, infections and health impairments (Kannan et al., 2006;Stavros et al., 2011). ...
... Until now, some links of mass mortality events to higher Hg concentrations in different organs including brain tissues were developed (Gajdosechova et al., 2016;Siebert et al., 1999;Squadrone et al., 2015). While no overt toxicity may be apparent, it has been suggested that subtle biochemical and neurochemical changes may occur (Krey et al., 2015;Stavros et al., 2011) before affecting the structure or function of the nervous system (Manzo et al., 2001). Squadrone et al. (2015) found that in stranded sperm whales, Hg values were within the range that has been demonstrated to result in Hg-associated neurotoxic effects, such as altered orientation and space perception. ...
Article
The study was carried out to determine Hg and Se concentrations in false killer whales stranded on the Estrecho de Magallanes, Chile, South America. Tissue samples of five mature specimens were analyzed (two females and three males). Mean Hg concentration in liver 1068 (234) μg g−1 dry weight (DW) (standard deviation in parenthesis) was markedly higher than those in kidney 272 (152) μg g−1 DW, lung 423 (325) μg g−1 DW, spleen 725 (696) μg g−1 DW, muscle 118 (94) μg g−1 DW and testicle 18.0 (2.8) μg g−1 DW. Mean Se concentration in liver, 398 (75) μg g−1 DW, was higher than those in kidney 162 (69) μg g−1 DW, lung 128 (84) μg g−1 DW, spleen 268 (245) μg g−1 DW, muscle 47 (38) μg g−1 DW and testicle 25.4 (2.1) μg g−1 DW. Positive correlations were found between Hg and Se molar concentrations in muscle, lung, spleen and kidney. Molar ratio of Se/Hg in liver, lung and muscle were <1, but those in kidney and testicle were markedly >1 suggesting a Se protection against Hg toxicity. In all the examined specimens Hg values exceeded the toxic thresholds defined for hepatic damage in marine mammals, with Se/Hg molar ratios below 1 implying limited protective action of Se. Generally, our results showed that individuals are carrying a significant burden, reflecting a high exposure to this toxic metal. This constitutes the first report on Hg and Se levels for a large subantarctic odontocete in South America region, providing insights into their contamination status and with information to the understanding of possible impacts on wild populations.
... Therefore, because MeHg has a low octanol-water distribution coefficient and is preferentially distributed in muscle tissues, blubber THg concentrations are generally less than those found in other tissues (e.g., kidney, liver, muscle, and skin) (Cardellicchio et al., 2002;Carvalho et al., 2002;Aubail et al., 2013). In contrast, dolphin skin (epidermis) has been shown to accumulate THg over time and between 70 and 100% of the THg found in bottlenose dolphin skin is in the form of MeHg (Yang et al., 2002;Stavros et al., 2007Stavros et al., , 2011Woshner et al., 2008;Aubail et al., 2013;Borrell et al., 2015). ...
... In the present study, mean skin THg concentrations for FL Table 2 Best fit general linear model (GLM) and parameter estimates selected based on the lowest Akaike Information Criteria (AIC c ). *Indicates variables were Log10 transformed. bottlenose dolphins (4.36 ± 3.55 μg/g dry wt) were comparable to the mean skin THg concentration found in bottlenose dolphins from Sarasota Bay, FL (4.02 ± 2.61 μg/g dry wt), but greater than the mean skin concentrations reported in bottlenose dolphins off the South Carolina (SC) coast (1.7 ± 0.92 μg/g dry wt) (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. In contrast, the mean skin THg concentration found in LA dolphins in the present study (1.94 ± 3.56 μg/g dry wt), was less than the mean concentration reported in Sarasota Bay, FL, but comparable to concentrations reported in dolphins off the SC coast (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. ...
... bottlenose dolphins (4.36 ± 3.55 μg/g dry wt) were comparable to the mean skin THg concentration found in bottlenose dolphins from Sarasota Bay, FL (4.02 ± 2.61 μg/g dry wt), but greater than the mean skin concentrations reported in bottlenose dolphins off the South Carolina (SC) coast (1.7 ± 0.92 μg/g dry wt) (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. In contrast, the mean skin THg concentration found in LA dolphins in the present study (1.94 ± 3.56 μg/g dry wt), was less than the mean concentration reported in Sarasota Bay, FL, but comparable to concentrations reported in dolphins off the SC coast (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. Annual wet Hg deposition across the northern Gulf of Mexico is greater than the wet deposition in SC, which may explain the greater THg concentration found in FL dolphins (Selin and Jacob, 2008); however, wet deposition patterns do not explain why THg concentrations in dolphins from LA and SC are similar. ...
Article
Due to their long life-span and top trophic position, odontocetes can accumulate high concentrations of mercury (Hg) in their tissues. This study measured the concentration of total Hg (THg) in the blubber and skin of bottlenose dolphins (Tursiops truncatus) that stranded along the Florida (FL) panhandle and Louisiana (LA) coasts and investigated the relationship between total Hg (THg) concentration and sex, body length, age, stranding location, diet/trophic position (δ13C and δ15N, respectively), and foraging habitat (δ34S). Additionally, we compared models using body length and age as explanatory variables to determine which was a better predictor of THg concentration. In both tissues, sex was not an influential predictor of THg concentration and there was a positive relationship between body length/age and THg concentration (p < 0.001). Florida dolphins had greater mean blubber and skin THg concentrations compared to LA dolphins (p < 0.001). There was a modest improvement in model fit when age was used in place of body length. δ13C, δ15N, and δ34S differed between stranding locations and together with age were significant predictors of THg concentrations (R2 = 0.52, P < 0.001). Florida dolphins were δ13C enriched compared to LA dolphins (p < 0.001) and THg concentrations were positively correlated with δ13C (R2 = 0.22, p < 0.001). Our results demonstrate spatial variability in THg concentrations from stranded bottlenose dolphins from the northern Gulf of Mexico; however, future research is required to understand how fine-scale population structuring of dolphins within FL and LA impacts THg concentrations, particularly among inshore (bay, sound, and estuary) stocks and between inshore and offshore stocks, as variations in biotic and abiotic conditions can influence both stable isotope ratios and THg concentrations.
... In previous studies, mean arsenic concentration in toothed whale skin was 0.6 μg/g ww (Carvalho et al., 2002;Bryan et al., 2007;Stavros et al., 2007;Stavros et al., 2011). In this study, mean arsenic concentrations in sperm whale skin were 1.9 μg/g ww, which is almost 3 fold higher than these past studies. ...
... Influences of age on arsenic concentration in marine mammals have typically not been seen in past studies (Kubota et al., 2001). There was not a positive correlation of arsenic concentrations in the skin of free-ranging bottlenose dolphins with age (Stavros et al., 2011). Also, there was not a positive correlation of renal or hepatic arsenic concentrations with age in La Plata dolphins from the Atlantic Ocean (Seixas et al., 2007). ...
... Arsenic concentrations that were measured in the skin of sperm whales in this study could be used to predict levels in internal organs where levels are more critical to overall health. Stavros et al. (2011) found using regression analysis that skin concentrations could be used to predict liver arsenic concentrations in bottlenose dolphins. Stranded bottlenose dolphins off the South Carolina coast had mean arsenic concentrations of 1.66 μg/g dw and 1.70 μg/g dw in skin and liver, respectively. ...
Article
Arsenic is an oceanic pollutant of global concern due to its toxicity, ability to bioaccumulate and continued input into the environment by anthropogenic activities. The sperm whale (Physeter macrocephalus) is an emerging aquatic model for both human disease and ocean health having global distribution and high trophic level. The aim of this study was to establish global and regional baselines of total arsenic concentrations using free-ranging sperm whales. Skin biopsies (n = 342) were collected during the voyage of the Odyssey (2000-2005) from 17 regions considering gender and age in males. Arsenic was detectable in 99% of samples with a global mean of 1.9 μg/g ww ranging from 0.1 to 15.6 μg/g ww. Previous work in toothed whale skin found mean concentrations 3 fold lower with 0.6 μg/g ww. A significant gender-related effect was found with males having higher mean arsenic concentrations than females. There was no significant age-related effect between adult and subadult males. Arsenic concentrations in sloughed skin samples were similar to levels in skin biopsies indicating arsenic excretion can occur by skin sloughing. Regional mean concentrations were highest in the Maldives, Seychelles and Sri Lanka with 3.5, 2.5, and 2.4 μg/g ww, respectively, raising concern for arsenic pollution in the Indian Ocean. Literature suggests arsenic exposure is emitted from natural sources and the heavy use of arsenic-containing pesticides and herbicides in this region. These data suggest research is needed in determining the extent and source of arsenic pollution in the Indian Ocean.
... The total Hg levels in the skin of the two groups, Fish-eaters and Seal-eaters were compared using Welch's t-test. There is a strong positive correlation between Hg levels in the skin and liver in toothed whales, and this can be used to compare Hg levels measured in skin with hepatic toxicity threshold values [56][57][58] . To extrapolate to liver from skin in our samples, we chose an equation based on a model using concentrations in the liver (Hg liver μg/g w.w) and skin (Hg skin μg/g w.w) of bottlenose dolphins (Tursiops truncatus) (Eq. 1) 58 . ...
... There is a strong positive correlation between Hg levels in the skin and liver in toothed whales, and this can be used to compare Hg levels measured in skin with hepatic toxicity threshold values [56][57][58] . To extrapolate to liver from skin in our samples, we chose an equation based on a model using concentrations in the liver (Hg liver μg/g w.w) and skin (Hg skin μg/g w.w) of bottlenose dolphins (Tursiops truncatus) (Eq. 1) 58 . We converted dry weight to wet weight using the water content for each individual whale measured during freeze drying. ...
... Horizontal lines represent the median, whiskers represent the lower (first) and upper (fourth) quartiles, dots represent individual whales, points outside the whiskers and box are outliers. (b) Levels in liver (μg/g w.w.), estimated from skin using equation ln Hg liver = 1.6124 × ln Hg skin + 2.0346 based on bottlenose dolphins (Tursiops truncatus)58 , and ordered on the x-axis in decreasing levels of total mercury within dietary groups. The red horizontal line (16 μg/g w.w.) is the threshold for a low risk of health effects in marine mammals, and ranges to 64 μg/g w.w. ...
Article
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Killer whales (Orcinus orca) are at risk from high levels of biomagnifying pollutants, such as polychlorinated biphenyls (PCBs) and mercury (Hg). Previous toxicological risk assessments for the Norwegian killer whale population have assumed fish as the primary prey source, and assessed the population as below established effect thresholds. However, some individuals have recently been identified to also feed on seals. This study is the first to quantify levels of pollutants in seal-eating killer whales from northern Norway, and to measure Hg levels in the skin of killer whales worldwide. We found higher levels of all pollutants in seal-eating than fish-eating killer whales, including the emerging brominated flame retardants pentabromoethylbenzene (PBEB), pentabromotoluene (PBT) and hexabromobenzene (HBB). Sum polychlorinated biphenyls (ΣPCBs) in the blubber of seal-eaters (n = 7, geometric mean = 46 µg/g l.w.) were four times higher than fish-eaters (n = 24, geometric mean = 11 µg/g l.w.), which pushed all seal-eating individuals above multiple thresholds for health effects. Total Hg levels in skin of seal-eaters (n = 10, arithmetic mean = 3.7 µg/g d.w.) were twice as high as in fish-eaters (n = 28, arithmetic mean = 1.8 µg/g d.w.). Our results indicate that by feeding on higher trophic prey, the Norwegian killer whale population is at higher risk of health effects from pollution than previously assumed.
... Therefore, because MeHg has a low octanol-water distribution coefficient and is preferentially distributed in muscle tissues, blubber THg concentrations are generally less than those found in other tissues (e.g., kidney, liver, muscle, and skin) (Cardellicchio et al., 2002;Carvalho et al., 2002;Aubail et al., 2013). In contrast, dolphin skin (epidermis) has been shown to accumulate THg over time and between 70 and 100% of the THg found in bottlenose dolphin skin is in the form of MeHg (Yang et al., 2002;Stavros et al., 2007Stavros et al., , 2011Woshner et al., 2008;Aubail et al., 2013;Borrell et al., 2015). ...
... In the present study, mean skin THg concentrations for FL Table 2 Best fit general linear model (GLM) and parameter estimates selected based on the lowest Akaike Information Criteria (AIC c ). *Indicates variables were Log10 transformed. bottlenose dolphins (4.36 ± 3.55 μg/g dry wt) were comparable to the mean skin THg concentration found in bottlenose dolphins from Sarasota Bay, FL (4.02 ± 2.61 μg/g dry wt), but greater than the mean skin concentrations reported in bottlenose dolphins off the South Carolina (SC) coast (1.7 ± 0.92 μg/g dry wt) (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. In contrast, the mean skin THg concentration found in LA dolphins in the present study (1.94 ± 3.56 μg/g dry wt), was less than the mean concentration reported in Sarasota Bay, FL, but comparable to concentrations reported in dolphins off the SC coast (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. ...
... bottlenose dolphins (4.36 ± 3.55 μg/g dry wt) were comparable to the mean skin THg concentration found in bottlenose dolphins from Sarasota Bay, FL (4.02 ± 2.61 μg/g dry wt), but greater than the mean skin concentrations reported in bottlenose dolphins off the South Carolina (SC) coast (1.7 ± 0.92 μg/g dry wt) (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. In contrast, the mean skin THg concentration found in LA dolphins in the present study (1.94 ± 3.56 μg/g dry wt), was less than the mean concentration reported in Sarasota Bay, FL, but comparable to concentrations reported in dolphins off the SC coast (Bryan et al., 2007;Stavros et al., 2007Stavros et al., , 2011. Annual wet Hg deposition across the northern Gulf of Mexico is greater than the wet deposition in SC, which may explain the greater THg concentration found in FL dolphins (Selin and Jacob, 2008); however, wet deposition patterns do not explain why THg concentrations in dolphins from LA and SC are similar. ...
... In our study, As concentrations were within the range of values reported for various stranded marine mammals. For instance, California sea lions from southern California (Harper et al., 2007) and bottlenose dolphins from south Carolina and Florida waters (Stavros et al., 2011). The bottlenose dolphins from this latter study also exhibited same range of V levels in their livers compared to porpoises stranded in our study. ...
... Moreover, the present hepatic V levels were in the same order of magnitude compared to those reported in other marine mammals such as, Beluga whales (Mackey et al., 1996), various pinnipeds (Saeki et al., 1999) and Caspian seals (Anan et al., 2002). An increase in the concentrations of V with age has been reported in several species of marine mammals and in addition V levels were correlated with Hg levels in the liver (Mackey et al., 1996;Saeki et al., 1999;Anan et al., 2002;Ikemoto et al., 2004;Stavros et al., 2011). Similarly, adult porpoises showed significant higher levels of V in livers compared to juveniles and a significant correlation was found between hepatic V and Hg accumulation ( Table 2). ...
... Heavy metals are well known environmental pollutants that accumulate in the bodies of odontocetes and potentially constitute a toxicological risk for the species (Caurant et al., 1996;Haraguchi et al., 2000;Endo et al., 2002;Stavros et al.,2008Stavros et al., , 2011. Seawater enrichment with heavy metals from natural occurrence or from anthropogenic impact may lead to an increase of metal burdens entering marine food chains (Fernandes et al., 2007). ...
... Data on As in striped dolphins are sparse (Becker et al., 1995;Hansen et al., 2015;Meador et al., 1999;Stavros et al., 2011). We found a couple of studies evaluating this metal in tissues of S.coeruleoalba from the Mediterranean Sea. ...
Article
Mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se)and arsenic (As)concentrations in internal tissues of 72 striped dolphins (Stenella coeruleoalba)from Murcia Region (Mediterranean coastline)have been investigated for the first time. Hg showed the highest concentration, followed by Se, Cd, As and Pb. In general, the levels of metal found in this study were similar to those described in similar studies in the Mediterranean Sea. However, in some adult specimens, Hg liver concentrations were related with toxic effects in cetacean. A significant correlation was observed with age, likewise between Se and Hg and Cd in tissues, which agree with detoxify effect attributed to Se through inert complex formation. Molar ratio Hg:Se in liver was close to 1:1 in some specimens, which would indicate overload of the Hg-Se detoxify function and compromised health. These results could contribute to a better knowledge of the distribution of these persistent pollutants in the Mediterranean Sea.
... Although Hg accumulation may be influenced by gender (Stavros et al., 2011), Hg concentrations are expected to be less in females due to the ability to pass their body burden of MeHg to their offspring through the placenta (Storelli and Macrotrigiano, 2000) or lactation (Frodello et al., 2000). Additionally, gender differences may be due to different hormone metabolisms causing a difference in accumulation (Caurant et al., 1996); males having a wider distribution than females with males feeding at the poles and at deeper depths; males being in contact with colder water temperatures where Hg speciation may differ; and males having a different diet preying on larger squid than females, which may have higher Hg concentrations (Whitehead, 2003). ...
... Studies have considered the most important biotic parameter to be considered is the age of marine mammals, since Hg potentially accumulates throughout life (Pompe-Gotal et al., 2009;Caurant et al., 1996). Several studies have found a positive correlation between Hg concentrations with age in the skin of dolphins, belugas and narwhals, which are all toothed whales (Miller et al., 2011;Stavros et al., 2011;Woshner et al., 2008;Lockhart et al., 2005;Wagemann and Kozlowska, 2005;Roditi-Elasar et al., 2003;Woshner et al., 2001;Monaci et al., 1998;Wagemann et al., 1998), and this was thought to be due to the bioaccumulation of Hg from birth and the fact that larger whales eat bigger and higher-trophic prey that contain greater amounts of Hg (Miller et al., 2011). It is unclear why our study did not find a correlation of Hg with age. ...
Article
Pollution of the ocean by mercury (Hg) is a global concern. Hg persists, bioaccumulates and is toxic putting high trophic consumers at risk. The sperm whale (Physeter macrocephalus), is a sentinel of ocean health due to its wide distribution, longevity and high trophic level. Our aim was to survey Hg concentrations worldwide in the skin of free-ranging sperm whales considering region, gender and age. Samples were collected from 343 whales in 17 regions during the voyage of the research vessel, Odyssey, between 1999 and 2005. Skin was analyzed for total Hg and detected in all but three samples with a global mean of 2.5±0.1μgg-1 ranging from 0.1 to 16.0μgg-1. The Mediterranean Sea had the highest regional mean with 6.1μgg-1 followed by Australia with 3.5μgg-1. Considering gender, females and males did not have significantly different global Hg concentrations. The variation among regions for females was significantly different with highest levels in the Mediterranean and lowest in Sri Lanka; however, males were not significantly different among regions. Considering age in males, adults and subadults did not have significantly different Hg concentrations, and were not significantly different among regions. The toxic effects of these Hg concentrations are uncertain. Selenium (Se), an essential element, antagonizes Hg at equimolar amounts. We measured total Se concentrations and found detectable levels in all samples with a global mean of 33.1±1.1μgg-1 ranging from 2.5 to 179μgg-1. Se concentrations were found to be several fold higher than Hg concentrations with the average Se:Hg molar ratio being 59:1 and no correlation between the two elements. It is possible Hg is being detoxified in the skin by another mechanism. These data provide the first global analysis of Hg and Se concentrations in a free-ranging cetacean.
... Stravos et al., 2011;Lailson-Brito et al., 2012). However, physiological and biochemical variations in organisms may disrupt this process, especially when associated with diseases (Colborn and Smolen, 2003;Stavros et al., 2011). The increase in mortality and immune system suppression observed in other cetacean species are associated with both high concentrations or chronic low-level exposure to mercury (Rawson et al., 1993;Bossart et al., 2003). ...
... The muscle loss is probably primarily due to food deprivation, since more than 50% of individuals collected in this UME had empty stomachs (Cunha et al., 2018). Indeed, inanition is often observed in diseases (Bossart et al., 2011;Muñoz et al., 2016) because of appetite loss and/or foraging inability (Miller, 1992;Ortiz et al., 2010). In this condition, lipid storage is preferentially metabolized, but in situations of prolonged starvation there is also protein catabolism (Ortiz et al., 2010). ...
Article
An unusual mortality event (UME) attributed to morbillivirus infection was identified in two Guiana dolphin populations from the Southeastern Brazilian coast. The aim of this study was to characterize total mercury (THg), methylmercury (MeHg) and selenium (Se) bioaccumulation and body burden in Guiana dolphins from Sepetiba Bay (RJ) collected before (n = 61) and during the UME (n = 20). Significantly lower Se concentrations were found in the livers of individuals collected during the UME (Mann-Whitney test; p = 0.03), probably due to impairment of the detoxification process in the liver. There were differences in THg and Se concentrations in the organs and tissues of individuals (Kruskal-Wallis test,p < 0.05), but not MeHg (Kruskal-Wallis test, p = 0.07). For THg, the liver showed the higher concentrations and differed among organs and tissues analyzed such as blubber (Tukey’s test for unequal N;p = 0.003). For Se concentrations, the skin and kidney presented the higher concentrations and varied among other tissues/organs, like muscle (Tukey’s test for unequal N; p = 0.02). Differences in body burdens were observed among specimens collected previously and during the UME probably due to the remobilization and transport of the muscle-stored MeHg to other tissues/organs. This abrupt input of MeHg into the bloodstream may cause serious health damage. Indeed, evidences of methylmercury intoxication was observed in Guiana dolphins in Sepetiba Bay. In conclusion, bioaccumulation patterns, the detoxification process and body burden were affected by morbillivirus.
... Stravos et al., 2011;Lailson-Brito et al., 2012). However, physiological and biochemical variations in organisms may disrupt this process, especially when associated with diseases (Colborn and Smolen, 2003;Stavros et al., 2011). The increase in mortality and immune system suppression observed in other cetacean species are associated with both high concentrations or chronic low-level exposure to mercury (Rawson et al., 1993;Bossart et al., 2003). ...
... The muscle loss is probably primarily due to food deprivation, since more than 50% of individuals collected in this UME had empty stomachs (Cunha et al., 2018). Indeed, inanition is often observed in diseases (Bossart et al., 2011;Muñoz et al., 2016) because of appetite loss and/or foraging inability (Miller, 1992;Ortiz et al., 2010). In this condition, lipid storage is preferentially metabolized, but in situations of prolonged starvation there is also protein catabolism (Ortiz et al., 2010). ...
Article
An unusual mortality event (UME) attributed to morbillivirus infection was identified in two Guiana dolphin populations from the Southeastern Brazilian coast. The aim of this study was to characterize total mercury (THg), methylmercury (MeHg) and selenium (Se) bioaccumulation and body burden in Guiana dolphins from Sepetiba Bay (RJ) collected before (n = 61) and during the UME (n = 20). Significantly lower Se concentrations were found in the livers of individuals collected during the UME (Mann-Whitney test; p = 0.03), probably due to impairment of the detoxification process in the liver. There were differences in THg and Se concentrations in the organs and tissues of individuals (Kruskal-Wallis test,p < 0.05), but not MeHg (Kruskal-Wallis test, p =0.07). For THg, the liver showed the higher concentrations and differed among organs and tissues analyzed such as blubber (Tukey’s test for unequal N; p = 0.003). For Se concentrations, the skin and kidney presented the higher concentrations and varied among other tissues/organs, like muscle (Tukey’s test for unequal N; p = 0.02). Differences in body burdens were observed among specimens collected previously and during the UME probably due to the remobilization and transport of the muscle-stored MeHg to other tissues/organs. This abrupt input of MeHg into the bloodstream may cause serious health damage. Indeed, evidences of methylmercury intoxication was observed in Guiana dolphins in Sepetiba Bay. In conclusion, bioaccumulation patterns, the detoxification process and body burden were affected by morbillivirus.
... Previously, skin biopsies have been suggested as a non-destructive tissue for assessing exposure to organic contaminants and the ecotoxicological risk associated for marine mammals (Fossi and Marsili, 1997;Fossi et al., 2004). Some studies have also investigated the potential use of skin samples obtained from freeranging cetaceans to monitor the bioaccumulation of trace elements in internal organs of striped dolphins Stenella coeruleolba (Monaci et al., 1998), minke whales Balaenoptera acutorostrata , Dall's porpoises Phocoenoides dalli (Yang et al., 2002) or more recently, bottlenose dolphins Tursiops truncatus (Stavros et al., 2011). Contrarily to skin, blubber has not been so much investigated for its potential use in trace element monitoring and only a limited number of studies reported trace element concentrations in this tissue (Fujise et al., 1988;Marcovecchio et al., 1990;Carvalho et al., 2002;Bustamante et al., 2003;Roditi-Elasar et al., 2003). ...
... The significant positive correlations in Hg concentrations between external and internal tissues suggest that cutaneous and sub-cutaneous Hg concentrations could be used to assess hepatic and renal Hg levels in the studied species. These results confirmed the positive correlations between skin and liver Hg concentrations established previously in cetacean species like Dall's porpoise (Yang et al., 2002), striped dolphin (Monaci et al., 1998) or bottlenose dolphin (Stavros et al., 2011). However, investigating correlations between liver and skin trace element concentrations in minke whales from the southern hemisphere by Kunito et al. (2002), reported positive correlations for Mn, Cu and Zn, but not for Hg, with the concentrations following the order Zn > Cu > Mn/ Hg, and with large interannual variations observed in the skin accumulation of one of the areas studied (i.e. ...
... Some individuals presented liver Hg concentrations over the range considered to pose a risk of hepatic damage (400-1600 mg/kg) (Wagemann and Muir, 1984). Even for those individuals in which Hg concentrations did not exceed this range, chronic low-level exposure of Hg could also suppress immune and endocrine system of animals, and increase in diseases, infections, and other health impairments (Caceres-Saez et al., 2018;Stavros et al., 2011). However, Se can protect marine mammals from Hg toxicity through antioxidant properties, competition for binding sites, and the formation of non-toxic inert complexes (Cuvin-Aralar and Furness, 1991). ...
... Concentrations of some trace elements in the epidermis of small cetaceans are significantly positive correlated with the concentrations in internal tissues in previous studies (Yang et al., 2002;Stavros et al., 2011;Aubail et al., 2013;Borrell et al., 2015;Zhang et al., 2017). However, in the present study, such correlations were not found, suggesting that the epidermis might not be a reliable monitoring tool to characterize trace elements accumulations, which are more likely to be present in internal tissues in this species. ...
Article
As a freshwater cetacean with a population of only approximately 1000 individuals, the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is threatened by water pollution. However, studies of contaminants accumulated in the Yangtze finless porpoise remain limited. In this study, concentrations of 11 trace elements in different tissues sampled from 38 Yangtze finless porpoise individuals were determined. The elements V, Ni, Zn, and Pb were mostly accumulated in the epidermis, Cr, Mn, Cu, Se, and Hg were mostly accumulated in the liver, while As and Cd were mostly accumulated in the blubber and kidney, respectively. The results show that trace elements concentrations in the epidermis do not reliably indicate concentrations in internal tissues of the Yangtze finless porpoises. Positive correlations between different trace elements concentrations in tissues with the highest concentrations suggested the similar mechanism of metabolism or uptake pathway of those elements. Concentrations of As, Se, Cd, Hg, and Pb in the tissues with the highest concentrations were significantly positively correlated with the body length. Furthermore, significantly higher trace elements concentrations were measured in the reproductive organs of females (ovaries) than males (testis). However, no significant difference of trace elements concentrations between habitats was found. In consideration of higher Hg and Cd level in Yangtze finless porpoises compared to other small cetaceans, the potential risk of Hg (in particular) and Cd toxicity to Yangtze finless porpoises needs further attention.
... For instance, reproductive organs are proved to accumulate heavy metals in rodents (Martiniakova et al. 2012), whilst skeletal muscles are relevant in hunted species to evaluate the risk for humans of consuming their meat (Gasparik et al. 2012;Pedersen and Lierhagen 2006). Skin and blubber are also used, namely in marine mammals, considering their high quantities of subcutaneous adipose tissue that potentially accumulates metals (Stavros et al. 2011;Yeats et al. 1999). However, there are currently no toxicological indicators to assess metal in the skin of these animals, unlike the liver (Stavros et al. 2011). ...
... Skin and blubber are also used, namely in marine mammals, considering their high quantities of subcutaneous adipose tissue that potentially accumulates metals (Stavros et al. 2011;Yeats et al. 1999). However, there are currently no toxicological indicators to assess metal in the skin of these animals, unlike the liver (Stavros et al. 2011). ...
Article
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Heavy metal and metalloid pollution is a matter of concern in animal, human and environmental health (One Health) and also in wildlife conservation worldwide. Studying wild mammals in toxicology has been contributing significantly to our knowledge, namely to find out the most critical regions, to understand bioaccumulation and biomagnification phenomena or to evaluate their toxic effects. However, not all the animal tissues and organs provide the same information or should be interpreted in the same way. The best sample to use will depend on the objectives and conditions of the study. This review aims to compare invasive and non-invasive samples to biomonitor heavy metals, providing a brief resume of their advantages, limitations and examples of use. Further research, using a wider range of mammalian species, is required to establish what information can be obtained in biomonitoring studies that use non-invasive samples (such as hair, faeces and parasites) and/or invasive samples (such as blood, liver, kidney, bone and other organs).
... In our study, As concentrations were within the range of values reported for various stranded marine mammals. For instance, California sea lions from southern California (Harper et al., 2007) and bottlenose dolphins from south Carolina and Florida waters (Stavros et al., 2011). The bottlenose dolphins from this latter study also exhibited same range of V levels in their livers compared to porpoises stranded in our study. ...
... Moreover, the present hepatic V levels were in the same order of magnitude compared to those reported in other marine mammals such as, Beluga whales (Mackey et al., 1996), various pinnipeds (Saeki et al., 1999) and Caspian seals (Anan et al., 2002). An increase in the concentrations of V with age has been reported in several species of marine mammals and in addition V levels were correlated with Hg levels in the liver (Mackey et al., 1996;Saeki et al., 1999;Anan et al., 2002;Ikemoto et al., 2004;Stavros et al., 2011). Similarly, adult porpoises showed significant higher levels of V in livers compared to juveniles and a significant correlation was found between hepatic V and Hg accumulation ( Table 2). ...
... TEs such as heavy metals could be taken up by marine organisms, entering the food chain and be potentially transferred to apex predators (Wang, 2002;Pan and Wang, 2012). High levels of TE contaminants have been documented in cetaceans from previous studies (Stavros et al., 2011;Mahfouz et al., 2014;Ferreira et al., 2016;Monteiro et al., 2016). However, the bioaccumulation and trophic transfer of TEs in N. phocaenoides have been less understood along the PRE. ...
... Most of the TEs examined in our study showed no significantly sexual differences, which were in agreement with those occurred in many marine mammals (Lavery et al., 2008;Stavros et al., 2011;Borrell et al., 2015). Renal Mn as an essential element was the only metal showing the bioaccumulation influence due to the sex difference, with the females containing less Mn than males (2.456 ± 0.540 vs. 4.032 ± 1.463 mg g À1 dw). ...
... As an apex predator, Atlantic bottlenose dolphins in the IRL have a long life span, bioaccumulate anthropogenic contaminants and have defined home ranges making them a valuable sentinel species [23]. The high mercury concentrations found in IRL dolphins may reflect environmental differences in mercury contamination that include deposition, biogeochemistry and trophic transfer [24]. Similarly, these factors impact the concentration of mercury found in fish species that local human populations may be consuming. ...
Article
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Mercury exposure through the consumption of fish and shellfish represents a significant public health concern in the United States. Recent research has demonstrated higher seafood consumption and subsequent increased risk of methylmercury exposure among subpopulations living in coastal areas. The identification of high concentrations of total mercury in blood and skin among resident Atlantic bottlenose dolphins (Tursiops truncatus) in the Indian River Lagoon (IRL), a coastal estuary in Florida, alerted us to a potential public health hazard in the contiguous human population. Therefore, we analyzed hair mercury concentrations of residents living along the IRL and ascertained their sources and patterns of seafood consumption. The total mean mercury concentration for 135 residents was 1.53 ± 1.89 µg/g. The concentration of hair mercury among males (2.02 ± 2.38 µg/g) was significantly higher than that for females (0.96 ± 0.74 µg/g) (p < 0.01). Log transformed hair mercury concentration was significantly associated with the frequency of total seafood consumption (p < 0.01). Individuals who reported consuming seafood once a day or more were 3.71 (95% CI 0.84-16.38) times more likely to have a total hair mercury concentration over 1.0 µg/g, which corresponds approximately to the U.S. EPA reference dose, compared to those who consumed seafood once a week or less. Hair mercury concentration was also significantly higher among individuals who obtained all or most of their seafood from local recreational sources (p < 0.01). The elevated human mercury concentrations mirror the elevated concentrations observed in resident dolphins in the same geographical region. The current study is one of the first to apply the concept of a sentinel animal to a contiguous human population.
... Spatial variation has been observed in the prevalence of the infectious disease, lobomycosis, in dolphins (Murdoch et al. 2008), and other infectious diseases such as orogenital papillomas (Bossart et al. 2005) and morbillivirus (Bossart et al. 2010, NOAA Fisheries 2014 have been confirmed in this population. The presence of multiple organic pollutants (Fair et al. 2007a(Fair et al. , 2007b and heavy metals (Stavros et al. 2011), as well as antibiotic-resistant bacteria (Greig et al. 2007) have been detected in individuals during capture-release health assessments. Three localized NOAA-declared unusual mortality events have occurred in the IRL in recent years including one ongoing event at time of writing (2001, 2008, and 2013-2014); the suspected cause of the 2001 event was the biotoxin saxitoxin, but it was not confirmed, and the cause of the 2008 and 2013-2014 events may be cetacean morbillivirus (NOAA Fisheries 2008. ...
Article
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Network analysis has recently been used to delve into the dynamics of cetacean sociality. Few studies, however, have addressed how habitat shape influences sociality, specifically how linear water bodies constrain the space where individuals might interact. We utilized network and spatiotemporal analyses to investigate association patterns and community structure in a bottlenose dolphin population in a linear estuarine system, the Indian River Lagoon (IRL), Florida. Using sighting histories from a multiyear photo-identification study we examined association patterns for 185 individuals collected over a 6.5 yr period (2002–2008). The population was highly differentiated (S = 0.723) and organized into six distinct social communities (Q = 0.544), spread in an overlapping pattern along the linear system. Social organization differed between communities, with some displaying highly interconnected networks and others comprising loosely affiliated individuals with more ephemeral associations. Temporal patterns indicated short-term associations were a significant feature of the fission-fusion dynamics of this population. Spatial analyses revealed that social structure was shaped by an individual's ranging patterns and by social processes including preference and avoidance behavior. Finally, we found that habitat “narrowness” may be a major driving force behind the sociality observed.
... The only exception is the case of Hg, which mainly accumulates in the liver (Das et al., 2003), hence why this is often the tissue used for monitoring Hg exposure. Previous studies found positive correlations of Hg concentrations between epidermis and liver tissues in Dall's porpoises (Phocoenoides dalli) (Yang et al., 2002), striped dolphins (Monaci et al., 1998) and bottlenose dolphins (Tursiops truncatus) (Stavros et al., 2011), indicating that epidermis can be used as a surrogate tool to monitor hepatic Hg concentrations. In addition, Aubail et al. (2013) recently published a study addressing this question in four Atlantic small cetacean species: the harbour porpoise (Phocoena phocoena) and the common (Delphinus delphis), bottlenose and striped dolphin. ...
... Species Date Location Condition n Pb level a Reference Oceanic Dolphin Bottlenose 1993–1998 Corisca S 7 0.8 (Fodello and Marchland, 2001) Bottlenose 1994 France S 3 <MDL Augier et al., 1993 Bottlenose 1998–2002 Portugal S 2 1.3 Carvalho et al., 2002 Bottlenose 2000–2007 SC, USA S 12 0.02 Stavros et al., 2011 Bottlenose 2002–2004 FL, USA F 40 0.02 Bryan et al., 2007 Bottlenose 2004–2005 SC, USA F 56 0.09 Stavros et al., 2007 Common 1998–2002 Portugal S 15 1.3 Carvalho et al., 2002 Common 1993–2001 Corisca S 2 0.6 (Fodello and Marchland, 2001) Pilot whale 1993–2001 Corisca S 3 1.1 (Fodello and Marchland, 2001) Risso's 1993–2001 Corisca S 3 0.6 (Fodello and Marchland, 2001) Striped 1993–1998 Corisca S 3 0.8 (Fodello and Marchland, 2001) Narwhal and Beluga Beluga 1982–1987 Canadian Arctic H 60 0.008 Wagemann et al., 1996 Narwhal 1992–1994 Eastern Arctic H 48 0.002 Wagemann et al., 1996 Porpoise Dall's porpoise 2000 Japan HF 1 0.005 Yang et al., 2006 Bowhead 2002–2003 AK, USA H 19 0.008 O'Hara et al., 2006 Sperm whale Sperm 2000–2005 Worldwide F 337 1.6 This study Sperm 2000–2005 Pacific F 30 2.5 This study Summary Toothed whales 1993–2007 Worldwide F, S, H, HF 689 0.4 ...
... The ability to biopsy live animals and compare blubber mercury concentrations to those from beach-cast individuals has considerable potential in marine mammal studies. Whilst a previous study by Stavros et al., [28] has found a slightly stronger relationship between mercury levels found in liver and skin, and used the method to make inferences about the health of free ranging animals, there are some limitations to using their method. Their study involved capture and release of animals and as such they are able to obtain larger samples of skin (approximately 0.5 g dry weight) than is able to be collected from the dart biopsy approach (0.03 g wet weight). ...
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Globally it is estimated that up to 37% of all marine mammals are at a risk of extinction, due in particular to human impacts, including coastal pollution. Dolphins are known to be at risk from anthropogenic contaminants due to their longevity and high trophic position. While it is known that beach-cast animals are often high in contaminants, it has not been possible to determine whether levels may also be high in live animals from the same populations. In this paper we quantitatively assess mercury contamination in the two main populations of a newly described dolphin species from south eastern Australia, Tursiops australis. This species appear to be limited to coastal waters in close proximity to a major urban centre, and as such is likely to be vulnerable to anthropogenic pollution. For the first time, we were able to compare blubber mercury concentrations from biopsy samples of live individuals and necropsies of beach-cast animals and show that beach-cast animals were highly contaminated with mercury, at almost three times the levels found in live animals. Levels in live animals were also high, and are attributable to chronic low dose exposure to mercury from the dolphin's diet. Measurable levels of mercury were found in a number of important prey fish species. This illustrates the potential for low dose toxins in the environment to pass through marine food webs and potentially contribute to marine mammal deaths. This study demonstrates the potential use of blubber from biopsy samples to make inferences about the health of dolphins exposed to mercury.
... All these samples were from subadult and adult specimens, corresponding to 45.5% of the total of subadults and adults in this study. Other authors obtained comparable results for stranded bottlenose dolphins in Australian and Floridian waters (Lavery et al., 2008;Stavros et al., 2011). These results coincided with animals with a Se/Hg molar ratio greater than 1. ...
... Elevated Hg levels have been recorded from the IRL in sediments and clams (Trefry and Trocine, 2011), crabs (Adams and Engel, 2014), game fish (Strom and Graves, 2001;Adams et al., 2003), and Atlantic bottlenose dolphins Tursiops truncatus. Blood and skin Hg concentrations in IRL dolphins were among the highest reported for the species worldwide (Stavros et al., 2007(Stavros et al., , 2008(Stavros et al., , 2011. Dietary sources of Hg likely contributed to high Hg levels in IRL dolphins (Stavros et al., 2007) and potentially other apex piscivores, but there have been no systematic surveys of Hg levels in key prey species from the IRL to determine their relative importance as sources of MeHg exposure. ...
Article
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Estuaries are important ecosystems for mercury methylation and accumulation, yet few studies have quantified mercury levels in prey species that expose large estuarine piscivores to contamination. We measured mercury concentrations in key prey species from the Indian River Lagoon, Florida, USA, to characterize variability and assess the spatial distribution of mercury levels throughout the estuary. Mean mercury concentrations ranged from 0.015mg/kg in Mugil cephalus to 0.222mg/kg in Bairdiella chrysoura and varied considerably in some species. Spatial variation was observed within species, but a universal geographic pattern among species was not apparent, likely reflecting the broad habitat-use patterns associated with the estuarine-transient life histories of many of these common prey species. In contrast, estuarine-resident species, such as B. chrysoura, may be useful indicators of regional mercury methylation potential and bioaccumulation in biota. These results can advance future studies that relate dietary mercury uptake and mercury level variations in estuarine piscivores. Copyright © 2015 Elsevier Ltd. All rights reserved.
... In this study, Arsenic concentrations ranged from 0.75 to 2.9, 0.2 to 1.7, 0.19 to 0.5 and 0.4 to 1.3 mg kg −1 in the liver, blubber, muscle and kidney, respectively. Data on Arsenic in marine mammals generally and S. coeruleoalba specifically, are sparse (Becker et al., 1995;Hansen et al., 2015;Meador et al., 1999;Stavros et al., 2011). The only available data on Arsenic concentrations in tissues of S. coeruleoalba from the Mediterranean Sea, are from 12 animals stranded along the Italian coasts and the concentrations were similar to those found in this study (Bellante et al., 2012a); (Table 3). ...
... Heavy metals in marine mammals (cetaceans, like dolphins and beluga) may produce alterations in the immune function and increase the incidence of infectious diseases (Cámara Pellissó et al., 2008). Different authors assessed trace element body burden in dolphins, all of them agreed on the need of establishing toxicological consequence of this metal accumulation (Lavery et al., 2008;Stavros et al., 2011) and spatial or temporal variations of stable inorganic and organic pollutant levels (Holsbeek et al., 1998;Raach et al., 2011;Yordy et al., 2010). Concentration of trace elements in tissues of seals revealed difference in species accumulation providing possible basis for the evaluation of species susceptibility (Ikemoto et al., 2004). ...
Article
Chemical elements and persistent organic pollutants (POPs) are globally present in aquatic systems and their potential transfer to loggerhead marine turtles (Caretta caretta) has become a serious threat for their health status. The environmental fate of these xenobiotics may be traced by the analysis of turtles' tissues and blood. Generally, loggerhead turtles exhibited a higher metal load than other turtle species, this could be explained by differences in diet habits being food the main source of exposure. Literature shows that muscle, liver and kidney are most considered for the quantification of chemical elements, while, organic compounds are typically investigated in liver and fat. This paper is an overview of the international studies carried out on the quantification of chemical elements, polychlorinated biphenyls (PCBs), organochlorines (OCs) and perfluorinated compounds (PFCs), in tissues, organs and fluids of C. caretta from the Mediterranean Sea, the Atlantic and the Pacific Oceans.
... Both studies found trace elements in skin a useful tool to monitor dolphin populations, as geographical location appeared to be a more important factor than other biological factors (age, sex) to explain differences in trace element concentrations. In addition, a significant correlation for total mercury in skin and liver of stranded and free-ranging dolphins was recently reported (Stavros et al. 2011), suggesting that skin can be useful in predicting mercury concentrations in the liver of free-ranging dolphins. Such a correlation is also an indication of a fast turnover of mercury and possibly other metals in marine mammal skin. ...
... Constant consumption coupled with long life span of cetaceans and long biological half-life of cadmium (10-30 years) supports age-dependent accumulation (Aguilar et al., 1999;Friberg, 1984;Woshner et al., 2001). Cadmium is a heavy metal commonly found in high concentrations within the liver and kidney of marine mammals (Brown et al., 2016;Krone et al., 1999;Stavros et al., 2011;Veinott and Sjare, 2006;Woshner et al., 2001). Cadmium occurs naturally in the environment as well as through anthropogenic sources such as the manufacturing of batteries, plastics, fertilizers, pesticides and paints; therefore, cadmium concentrations along the coastline may be at levels that affect cetaceans (Krone et al., 1999;Noel et al., 2004;Savery et al., 2015;Woshner et al., 2001). ...
Article
An 8X15k oligonucleotide microarray was developed consisting of 2334 Eubalaena glacialis probes and 2166 Tursiops truncatus probes and used to measure the effects, at transcriptomic level, of cadmium exposure in right whale kidney fibroblast cells. Cells were exposed to three concentrations (1 μM, 0.1 μM, and 0.01 μM) of cadmium chloride (CdCl2) for three exposure times (1, 4, and 24 h). Cells exposed to 1 μM CdCl2 for 4 h and 24 h showed upregulated genes involved in protection from metal toxicity and oxidative stress, protein renaturation, apoptosis inhibition, as well as several regulators of cellular processes. Downregulated genes represented a suite of functions including cell proliferation, transcription regulation, actin polymerization, and stress fiber synthesis. The collection of differentially expressed genes in this study support proposed mechanisms of cadmium-induced apoptosis such as ubiquitin proteasome system disruption, Ca²⁺ homeostasis interference, mitochondrial membrane potential collapse, reactive oxygen species (ROS) production, and cell cycle arrest. The results also have confirmed the right whale microarray as a reproducible tool in measuring differentiated gene expression that could be a valuable asset for transcriptome analysis of other baleen whales and potential health assessment protocols.
... That being said, the Se:Hg molar ratio can also be influenced by the distribution and deposition of Se; for example, among tissues, following the liver, odontocete skin often had the second greatest mean Se concentration. High Se concentrations in the skin, which is thought to be associated with UV protection, in combination with low THg concentrations in the skin, result in Se:Hg molar ratios >1:1 (McKenzie, 2000;Stavros et al., 2011;Cáceres-Saez et al., 2015). ...
Article
Odontocetes are apex predators that, despite accumulating mercury (Hg) to high concentrations in their tissues, show few signs of Hg toxicity. One method of Hg detoxification in odontocetes includes the sequestering of Hg in toxically inert mercury selenide (HgSe) compounds. To explore the tissue-specific accumulation of Hg and Se and the potential protective role of Se against Hg toxicity, we measured the concentrations of total mercury (THg) and selenium (Se) in multiple tissues from 11 species of odontocetes that stranded along the northern Gulf of Mexico coast [Florida (FL) and Louisiana (LA)]. Tissues were collected primarily from bottlenose dolphins (Tursiops truncatus; n = 93); however, individuals from species in the following 8 genera: Feresa (n = 1), Globicephala (n = 1), Grampus (n = 2), Kogia (n = 5), Mesoplodon (n = 1), Peponocephala (n = 4), Stenella (n = 9), and Steno (n = 1) were also sampled. In all species, the mean THg concentration was greatest in the liver and lowest in the blubber, lung, or skin. In contrast, in most species, the mean Se concentration was greatest in the liver, lung, or skin, and lowest in the blubber. For all species, Se:Hg molar ratios decreased with increasing THg concentration in the blubber, kidney, liver, lung, and skin following an exponential decay relationship. In bottlenose dolphins, THg concentrations in the kidney, liver, and lung were significantly greater in FL dolphins compared to LA dolphins. On average, in bottlenose dolphins, Se:Hg molar ratios were approximately 1:1 in the liver and >1:1 in blubber, kidney, lung, and skin, suggesting that Se likely protects against Hg toxicity. However, more research is necessary to understand the variation in Hg accumulation within and among species, and to assess how Hg, in combination with other environmental stressors, influences odontocete population health.
... Similarly, cetaceans, which are also large predators and which feed on cephalopods and fish, can accumulate large amounts of mercury in their tissues as a result of their longevity and trophic level (Borrell et al., 2014). For this reason, dolphins are considered to be sentinels in the monitoring of spatial and temporal trends in many aquatic pollutants (Augier et al., 1993;Bellante et al., 2011;Stavros et al., 2011;Reif et al., 2015). ...
Article
Pollution from heavy metals is becoming a serious and widespread problem due to their persistent and bioaccumulative nature, moreover in the Mediterranean Sea, threatening food safety and the health of humans and marine animals. Cadmium and mercury in particular, are considered two of the most toxic metals to living organisms. Their presence is associated with the contribution of human activity, implying an increased level in the different environmental compartments and the inevitable bioaccumulation in the food chain. In this study, levels of cadmium and mercury were determined in liver, kidney, and muscle tissue of dolphinid specimens of Stenella coeruleoalba stranded in different locations along the coastal areas of the Tyrrhenian and Ionian Sea in Southern Italy, during the period 2015–2018 by Atomic Absorption Spectrophotometry. Data were compared with those reported for other locations along the Mediterranean sea. The correlations between biometric data (body length, weight and gender) and cadmium and mercury concentrations in samples of cetaceans were statistically analysed in order to investigate the risk these contaminants may pose to the delphinids health. Examination of the pattern of contaminants revealed a significantly high distribution for mercury in all the matrices analyzed (liver, kidney and muscle tissue). On the contrary, elevated concentrations of cadmium were found only in liver (range: 0.005 - 8.95 mg/kg w.w.) and kidney (range: 0.005 - 34.1 mg/kg w.w.) due to accumulator role of these organs in long-term exposures.
... It is known that heavy metals are environmental contaminants that accumulate in the organs of odontocetes and potentially are a toxicological risk for this species (Stavros et al. 2011). Mercury (Hg) is one of this trace elements of most worry due to toxicity and its bioaccumulation in the environment and biota (Borrell et al. 2014). ...
Article
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We determinated Hg and Se concentrations in liver, kidney, brain, lung and muscle of five bottlenose dolphin (Tursiops truncatus), four common dolphins (Delphinus delphis) and four Risso’s dolphin (Grampus griseus) stranded along the Murcia coast, Southeast Spain, in order to evaluate the risk of Hg toxicity. Hg concentrations showed similar concentrations to other individuals in the Mediterranean Sea with the same length in the same period. We observed a positive correlation of Hg and Se in liver (r = 0.948, p < 0.001) and kidney (r = 0.939; p = 0.001) and ratio the Se/Hg molar was higher than 1 in most cases. Our results suggest that the protective effects of Se against Hg toxicity occur in cetaceans. However, we detected levels of Hg described as responsible liver damage and neurotoxicological effects so other tools, as biochemical markers, should be included. Besides, more studies are needed to evaluate the risk of Hg exposure in dolphins from Murcia coastline.
... While skin biopsies are limited in scope to evaluate burden of metal levels in internal organs, several studies have found positive correlations between metal levels observed in skin to those observed in internal organs such as liver and kidney for Cr, Hg, Mn, Cu, and Zn [19][20][23][24][25][26]. Fin whale levels were reported in organs other than skin, although Al, Cr or Ni, the highest toxic metal levels in these Gulf of Maine whales were not considered in these studies. ...
Article
One Environmental Health has emerged as an important area of research that considers the interconnectedness of human, animal and ecosystem health with a focus on toxicology. The great whales in the Gulf of Maine are important species for ecosystem health, for the economies of the Eastern seaboard of the United States, and as sentinels for human health. The Gulf of Maine is an area with heavy coastal development, industry, and marine traffic, all of which contribute chronic exposures to environmental chemicals that can bioaccumulate in tissues and may gradually diminish an individual whale's or a population's fitness. We biopsied whales for three seasons (2010-2012) and measured the levels of 25 metals and selenium in skin biopsies collected from three species: humpback whales (Megaptera novaeangliae), fin whales (Balaenoptera physalus), and a minke whale (Balaenoptera acutorostrata). We established baseline levels for humpback and fin whales. Comparisons with similar species from other regions indicate humpback whales have elevated levels of aluminum, chromium, iron, magnesium, nickel and zinc. Contextualizing the data with a One Environmental Health approach finds these levels to be of potential concern for whale health. While much remains to understand what threats these metal levels may pose to the fitness and survival of these whale populations, these data serve as a useful and pertinent start to understanding the threat of pollution.
... Therefore, studies on the trophic transfer of metals would determine the principal route of human beings exposed to chemical toxicants (Walton et al. 2010). Numerous studies on the bioaccumulation of trace elements in organisms have been conducted in recent years (Hui-Chen et al. 2011;Zhang et al. 2015;Yang-Guang et al. 2015;Jitar et al. 2015;Nel et al. 2015;Dias and Nayak 2016;Monferrán et al. 2016;Wang et al. 2018;Sankar et al. 2018;Bonsignore et al. 2018;Rajeshkumar and Li 2018). Understanding the distribution of metals in marine organisms is considered to be a crucial part of investigation as it specifies the health of an ecosystem (Jezierska and Witeska 2006). ...
Article
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Trace element (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, As, Hg) concentrations were assessed in marine organisms (n = 52) sampled from the Magdalena Bay lagoon complex in Baja California Sur, Mexico, a pristine marine environment. The overall trend of metal concentrations (dry weight) in the organisms was found to be Fe > Zn > Cd > Cu > Mn > Pb > As > Hg > Ni > Cr > Co. Bivalve mollusks (53.83 mg kg⁻¹) contained twofold higher levels of metals than the finfishes (20.77 mg kg⁻¹). Calculated BioConcentration Factor (BCF) values showed that dissolved Mn is readily bioavailable to the organisms, whereas Biota Sediment Accumulation Factor (BSAF) indicated high values for Zn, Cu and Cd. Cd and As levels were observed to be increasing with the trophic levels. Toxic elements, namely Pb, Cd and As in the studied fish species were found to be higher than the values recommended for human seafood consumption. The study provides a comprehensive baseline report on trace element bioaccumulation in several marine organisms that will aid in developing effective conservation strategies of the highly biodiverse lagoon complex.
... Značajne razlike koncentracija mangana u koži utvrđene su s obzirom na geografsku poziciju nalaska dobrih dupina u svjetskim morima, te su se kretale u rasponu od 0,055 do 0,88 mg/ kg (Bryan i sur., 2007., Stavros i sur., 2007., 2011., Aubail i sur., 2013. Širok raspon koncentracija u koži sugerira da geografska lokacija može biti važan čimbenik u razlikama u koncentraciji mangana u koži (Kunito i sur., 2002.). ...
Article
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Manganese is an essential element involved in a number of metabolic functions, including skeletal system development, energy metabolism, specific enzyme activation, nervous system function, connective tissue growth, blood clotting, immune function, and proper function of reproductive hormones. It is also an antioxidant that protects cells from free radicals, and is a cofactor in a series of enzymatic reactions. Deficiency of manganese in animals affects carbohydrate metabolism, decreased glucose metabolism, poor lipid metabolism and decreased synthesis and insulin activity. Manganese accumulates in mitochondrial cells, and therefore, tissues rich in these organelles, such as the pancreas, liver, kidneys and intestine, have the highest concentrations of manganese. It also easily crosses the blood-brain barrier and accumulates in specific regions of the brain. Therefore, chronic inhalation of high concentrations of manganese affects the brain, causing central nervous system disorders and neurobehavioral disorders. The effects of manganese as a trace element with potential toxicity to marine mammals, such as dolphins, have not yet been explored. The main load factor of manganese in mammals is diet, with metal content varying widely among species and tissues. The expected range of manganese in marine mammal tissues is up to 7 mg/kg wet weight. The highest concentrations, ranging from 2.15 to 5.34 mg/kg, were determined in the livers of the three species of kite whale (Cetacea) dolphins present in all seas, including the Mediterranean and Adriatic Sea: bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba), and Risso's (Grampus griseus) dolphins. Studies conducted for the determination of manganese concentrations in dolphin tissues have shown the concentration order liver > kidneys > muscles. Also, manganese concentrations in the tissues of the three dolphin species from the Mediterranean showed similar values in tissues, especially liver, kidneys, muscles and lungs. There are few reports on manganese concentrations in dolphins from the Italian coast of the Adriatic Sea. Comparison of manganese concentrations in the tissues of bottlenose and striped dolphins from other world seas, i.e., the American, Brazilian and Portuguese coasts of the Atlantic and the Pacific islands of Hawaii and Japan, showed similar values to those determined in the dolphin tissue from the Mediterranean. There were no available literature data for Risso's dolphins from the world seas. Significant differences in manganese concentrations were found in the skin due to the global geographical position of the bottlenose dolphins, suggesting that geographic location may be an important factor influencing manganese concentrations.
... However, Mn in the skin of S. coeruleoalba was 2 to 4 times lower than the concentrations determined in the skin of dolphins from the Israeli coast and Atlantic coast of Portugal (Roditi-Elasar et al. 2003;Aubail et al. 2013). In comparison with Mn levels in skin of T. truncates in present study, significantly different concentrations have been reported with regard to the sampling site for this species in the world's seas, ranging from 0.0547 to 0.875 mg/kg (Bryan et al. 2007;Stavros et al. 2007Stavros et al. , 2011Aubail et al. 2013). According to wide range of concentrations found in skin it can be concluded that the geographic location may be an important factor influencing Mn levels in skin (Kunito et al. 2004). ...
Article
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Manganese concentrations were determined in muscle, kidney, liver, spleen, lung and fat tissues and skin of three cetacean species, the bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba) and Risso’s (Grampus griseus) dolphins, stranded along the Croatian Adriatic coast between 1995 and 2013. Mean ranges determined in tissues were (mg/kg, ww): muscle 0.23–0.27, liver 2.87–4.00, kidney 0.66–1.26, spleen 0.37–0.79, lung 0.18–0.57, skin 0.11–0.97, fat 0.06–0.42. The highest Mn mean levels in tissues were measured in species (mg/kg, ww): T. truncates lung 0.41, skin 0.97, fat 0.42; S. coeruleoalba muscle 0.26; G. griseus kidney 1.26, liver 4.00, spleen 0.64. Significant differences of Mn concentrations in the liver (p = 0.034), spleen (p = 0.037) and skin (p = 0.013) were found among the three dolphin species. Significant differences in Mn levels were found between young and adult T. truncates in kidney (p = 0.042), lung (p = 0.0040) and skin (p = 0.0034).
... These concentrations significantly exceeded those in dolphins from CHS (Stavros et al. 2007(Stavros et al. , 2008 and are among the highest recorded worldwide . Similarly, the concentrations of THg in the liver of stranded IRL dolphins were approximately 10 times higher than those in dolphins stranded near CHS and were significantly correlated with skin concentrations (Stavros et al. 2011). ...
Article
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Bottlenose dolphins Tursiops truncatus are the most common apex predators found in coastal and estuarine ecosystems along the southeastern coast of the USA, where these animals are exposed to multiple chemical pollutants and microbial agents. In this review, we summarize the results of investigations of environmental exposures evaluated in 360 free-ranging dolphins between 2003 and 2015. Bottlenose dolphins inhabiting the Indian River Lagoon, Florida (IRL, n = 246), and coastal waters of Charleston, South Carolina (CHS, n = 114), were captured, given comprehensive health examinations, and released as part of a multidisciplinary and multi-institutional study of individual and population health. High concentrations of persistent organic pollutants including legacy contaminants (DDT and other pesticides, polychlorinated biphenyl compounds) as well as 'emerging' contaminants (polybrominated diphenyl ethers, perfluorinated compounds) were detected in dolphins from CHS, with lower concentrations in the IRL. Conversely, the concentrations of mercury in the blood and skin of IRL dolphins were among the highest reported worldwide and approximately 5 times as high as those found in CHS dolphins. A high prevalence of resistance to antibiotics commonly used in humans and animals was detected in bacteria isolated from fecal, blowhole, and/or gastric samples at both sites, including methicillin-resistant Staphylococcus aureus (MRSA) at CHS. Collectively, these studies illustrate the importance of long-term surveillance of estuarine populations of bottlenose dolphins and reaffirm their important role as sentinels for marine ecosystems and public health.
... For context, background arsenic levels in tissue of most other living animals are usually <1 ppm ww, including humans (Eisler, 1988;Gomez-Caminero et al., 2001). Low levels have also been reported for alligator and crocodile eggs (0.05-0.2 and 0.2 ppm ww, respectively; (Eisler, 1988), and most marine mammals contain generally <1 ppm in liver and muscle (Muir et al., 1988;Varanasi et al., 1994;Neff, 1997;Gomez-Caminero et al., 2001;Stavros et al., 2011;Poulsen and Escher, 2012). ...
Technical Report
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The objective of the present study was to measure the concentration of contaminants in blood of live green turtles captured in the Boyne River estuary near Gladstone, and to evaluate whether the contaminant levels are elevated and may pose a risk to the health of the turtle population. During early 2011, Port Curtis experienced approximately 5 times higher mortality rates of sea turtles compared to previous years, as well as increased mortality rates of other wildlife species. In July 2011, an evaluation of the health status of live and diseased local green turtles was conducted. In parallel with this investigation, blood was collected from 40 live green turtles to assess exposure to a range of organic and inorganic contaminants that may be associated with agricultural, urban and industrial activities and that are known to accumulate in marine wildlife and may present a hazard to these species. Three of these 40 green turtles had to be euthanised due to poor diagnoses for survival, providing liver and kidney samples in addition to blood. Additional liver and fat samples were also obtained from stranded specimens. The measured levels of contaminants in the Boyne River estuary turtle samples were compared to the levels reported in the peer-reviewed scientific literature for other green turtles, sea turtles and, where limited information was available, other vertebrates from both polluted and relatively low impacted areas. These levels were further evaluated against reported contaminant concentrations in a range vertebrate species where either chronic health effects (after long term exposure to contaminants) or acute health effects (after short term exposure) have been observed. Based on these assessments, the contaminants that were found in the turtle samples were classified into three categories: 1. Contaminants were considered of “relatively low concern” if they were detected in the Boyne River turtles at relatively low concentrations that were comparable to those reported for most other sea turtles and vertebrates, including those considered healthy and originating from relatively low impacted areas. At these levels, no associated adverse health effects have been reported in the scientific literature for turtles or other vertebrate species. Contaminants assigned to this category were: bioaccumulative pesticides, organotins, flame retardants (polybrominated diphenyl ethers (PBDEs)), perfluorinated compounds (perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)), aluminium (Al), iron (Fe), manganese (Mn), and zinc (Zn). 2. Contaminants were considered “possibly of concern” if they were present at concentrations that were comparable to the upper ranges of those reported for other sea turtles and vertebrates. Where relevant information was available, the contaminant levels in a proportion of the Boyne River green turtles were found to be above the concentrations where chronic effects occur in other vertebrates; i.e. long term exposure at these levels may result in adverse health effects. In contrast, the levels in the turtles were lower than the concentrations expected to result in adverse health effects after short term, acute exposure to these compounds. Contaminants that fell within this category were: polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (PCBs), silver (Ag), copper (Cu), chromium (Cr), molybdenum (Mo), and lead (Pb). 3. Contaminants were considered “of concern” if their concentrations were clearly higher compared to most other green turtles and sea turtles, or within the upper levels reported from animals that were moribund and/or originated from areas considered relatively polluted. These contaminants were also present at higher levels compared to normal concentrations known for other vertebrates from low impacted or unpolluted areas. In particular, the measured concentrations in Boyne River turtles were found to be above or near the concentrations where acute adverse health effects have been observed across different vertebrate taxa. Although the sensitivity of sea turtles to these contaminants is mostly unknown, this suggests that adverse health effects are possible in the Boyne River estuary turtle population at the detected concentrations. Contaminants that fell within this category were: arsenic (As), cadmium (Cd), cobalt (Co), mercury (Hg), nickel (Ni), selenium (Se), and vanadium (V). It should be noted that information on the sensitivity of green turtles to contaminants are limited. For this study, as for other studies reported in the scientific literature, comparisons to other vertebrates were required in most instances. There is, therefore, an uncertainty involved when evaluating the effects that a particular concentration of contaminants may have on green turtles. Considering these results, it is recommended to monitor the health and contaminant levels in adult and juvenile green turtles from Gladstone as well as other, suitable control populations. Investigation of contaminants with strong tendencies to biomagnify in marine biota should be carried out across species of different trophic levels, and detailed speciation of metal/metalloids should be considered to provide a better understanding on the risks associated with the compounds of concern based on total metal/metalloid concentrations.
... Furthermore, mangrove mud is naturally acidic (pH 3e4), which facilitates mercury availability for anaerobic bacteria. Indeed, when elemental mercury (Hg 2þ ) binds to the DOC (dissolved organic carbon) it is rarely methylated because DOC molecules are too large to pass Fig. 7. Review of mean T-Hg concentrations (mg kg À1 dw) in skin of bottlenose dolphins from Florida from the literature (Woshner et al., 2008;Stavros et al., 2011) and the present study (blue lines). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) ...
Article
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Social network analysis has been shown to be effective in studying the social structure of cetacean populations. Common bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon (IRL), Florida, have among the highest concentrations of total mercury (THg) in blood reported worldwide. The purpose of this study was to examine the relationship between THg concentrations in IRL dolphins and their social affiliations. Whole blood samples from 98 dolphins with photo-identification sighting histories were collected between 2003–2007 and 2010–2012. Dolphins were categorized into approximate tertiles of low (mean 199.7 μg/L), medium (mean 366.8 μg/L), and high (mean 990.5 μg/L) THg exposure. Social associations between individual dolphins were defined by the proportion of sightings documented with another known individual. Social network measures of individuals and associations between dyads were examined to determine differences among THg categories. Strong social affiliations of individuals within the highest category of THg were found (P = 0.04), suggesting shared exposures among dolphins foraging in specific areas of the estuary. Network measures of strength and affinity were significantly higher in the highest exposure category. This report used social network analysis as a novel way to examine patterns of exposure to an environmental contaminant in a cetacean population.
Article
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Mercury (Hg) is a ubiquitous global contaminant with important public health implications. Mercury is released from a variety of anthropogenic, industrial processes, enters the earth's atmosphere and is re-deposited onto the earth’s surface in rainfall. Much of this Hg enters the oceans which cover the majority of the earth’s surface. In the marine environment, inorganic Hg is converted to the most toxic form of the element, methylmercury, and biomagnified through the trophic levels of the food web. The bottlenose dolphin (Tursiops truncatus) is the apex predator in many estuarine and coastal ecosystems. Due to their long life span and trophic position, bottlenose dolphins bioaccumulate high concentrations of contaminants including Hg, thus making them an important sentinel species for ecosystem and public health. Bottlenose dolphins in Florida bioaccumulate high concentrations of Hg in their blood, skin and internal organs. The concentrations of Hg in blood and skin of bottlenose dolphins of the Indian River Lagoon, FL (IRL) are among the highest reported world-wide. In previous studies, we demonstrated associations between concentrations of total Hg in the blood and skin of IRL dolphins and markers of endocrine, renal, hepatic, hematologic and immune system dysfunction. The predominant manifestation of exposure to mercury in humans is neurotoxicity. During the 1950s and 1960s, residents of Minamata bay, Japan were exposed to high concentrations of methyl mercury as the result of ingestion of fish and shellfish that had become contaminated in this infamous environmental disaster. Affected adults had severe motor and sensory abnormalities often leading to death. Methyl mercury crosses the placenta during pregnancy. Children exposed in utero were born with multiple congenital anomalies and also suffered from neurologic disorders. Significantly, local cats that consumed Hg contaminated fish developed severe signs of neurotoxicity which led to their subsequent description as the “dancing cats of Minamata bay”. Unfortunately, the cause of these strange manifestations in cats was not recognized in time to prevent hundreds of additional cases from occurring. More recent studies have shown that exposure to mercury as a result of seafood consumption during pregnancy may result in multiple cognitive and neurodevelopmental effects in children. The levels of mercury found in bottlenose dolphins and the health effects we identified alerted us to the possibility of an important public health hazard. The IRL occupies 40 percent of the east coast of Florida and is bordered by counties with approximately 2.5 million human inhabitants. Therefore, we hypothesized that local inhabitants in communities bordering the IRL could be at risk of exposure to Hg from the consumption of fish and shellfish. We measured hair Hg in 135 local residents and found a mean concentration of 1.53 µg/g which was higher than that from previous studies of sport fishermen and coastal residents in other states. Over 50% of participants had a hair Hg concentration which exceeded the U.S. EPA exposure guideline. Hair Hg concentration was directly related to the frequency of seafood consumption and to the proportion of fish and shellfish obtained from local recreational sources. This study clearly exemplifies the importance of an animal sentinel in identifying a public health hazard and is virtually unique in “closing the loop” between animal and human health.
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Few studies report trace elements in dwarf sperm whale (Kogia sima). As high trophic level predators, marine mammals are exposed through diet to environmental contaminants including metals from anthropogenic sources. Inputs of Hg, Pb, and Cd are of particular concern due to toxicity and potential for atmospheric dispersion and subsequent biomagnification. Liver and kidney tissues of stranded K. sima from coastal South Carolina, USA, were analyzed for 22 trace elements. Age-related correlations with tissue concentrations were found for some metals. Mean molar ratio of Hg:Se varied with age with higher ratios found in adult males. Maximum concentrations of Cd and Hg in both tissues exceeded historical FDA levels of concern, but none exceeded the minimum 100μg/g Hg threshold for hepatic damage. Tissue concentrations of some metals associated with contamination were low, suggesting that anthropogenic input may not be a significant source of some metals for these pelagic marine mammals.
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An important step to define conservation management strategies for natural populations is to analyze their genetic structure and dynamics based on biological samples of free-ranging individuals. In small cetaceans, biological material for genetic analyses can be obtained by skin swabbing or biopsy darting. Gender of individuals is usually not known by the time of sampling and it is determined in the lab by molecular sexing. We determined the gender of 340 biopsy samples of bottlenose dolphins, Tursiops truncatus, spotted dolphins, Stenella frontalis, and common dolphins, Delphinus delphis, collected around the archipelagos of the Azores and Madeira. Although differences existed between species and archipelagos, sex ratio was globally skewed in favour of males. Bias could result from selectivity of the biopsy collectors, seasonal or actual predominance of males in natural populations, behavioural avoidance of boats by females and defence behaviour of males. Field-based observations suggested that the sample sex ratio did not adequately reflect the population sex ratio. When several samples were collected within the same group, the proportion of female samples decreased exponentially as a function of sample order. This result indicated a tendency for females to increasingly avoid the boat while samples were being collected, and showed that males and females reacted differently to the biopsy sampling process. As a consequence, it seems advisable to sample only one or two individuals per group. This will limit animal perturbation and allow for a better assessment of sex ratio and its seasonal fluctuations in natural populations.
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This paper is an account of preparation and examination techniques and criteria used to estimate age in decalcified and stained tooth thin sections from spinner and spotted dolphins. A dentinal growth layer group (GLG), composed of two thin light and two thicker dark-stained layers, is deposited annually. The GLG component layers are variably visible, but the "ideal" pattern and successive thinning of dentinal GLGs are used as a guide to determine GLG limits. Age-specific thicknesses of dentinal GLGs found in Hawaiian spinner dolphin teeth seem to be applicable to teeth of spotted dolphins and can be used as an aid in locating GLG boundaries. Cemental GLGs are composed of a dark-stained and a lightly stained layer and usually are deposited at a rate of one per year, but may be deposited every other year or two or three times per year. Two slightly different methods of counting dentinal GLGs are presented, along with guidelines for determining whether dentinal or cemental GLG counts provide the best estimate of age for a specimen.
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The Florida Fish and Wildlife Conservation Commission’s Florida Marine Research Institute (FWC-FMRI) has examined total mercury levels in muscle tissue from a variety of economically and ecologically important species as part of an ongoing study to better understand mercury contamination in marine fishes. The FWC-FMRI Mer­cury Program is one of the most comprehensive programs in the United States for monitoring mercury levels in marine and estuarine fishes. Because mercury, a toxic metallic element, has been shown to bioaccumulate in fish tissue, humans consuming fish can potentially consume significant levels of mercury. We examined the concen­tration of total mercury in 6,806 fish, representing 108 species from 40 families. Species represented all major trophic groups, from primary consumers to apex predators.The majority of individuals we examined contained low con­centrations of mercury, but concentrations in individual fish varied greatly within and among species. Species with very low mean or median mercury concentrations tended to be planktivores, detritivores, species that feed on invertebrates, or species that feed on invertebrates and small fish prey. Apex predators typically had the high­est mercury concentrations. In most species, mercury concentration increased as fish size increased. Sampling in Florida waters is continuing, and future research relating mercury levels to fish age, feeding ecology, and the trophic structure of Florida’s marine and estuarine ecosystems will help us better understand concentrations of this element in marine fishes.
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Intracellular storage and levels of mercury and selenium were studied in the livers of top marine predators belonging to different vertebrate taxa. Total mercury levels showed very important interspecific variations, ranging from 2.6 mu g g(-1) in tuna and swordfish to several thousand mu g g(-1) (dry weight) in bottle-nosed and Risso's dolphins. However, methylmercury was less variable, ranging from 1 to 174 mu g g(-1) (dry weight). The ratio between Hg and Se levels was close to equimolarity in marine mammals and cormorants, but a large excess of selenium in relation to mercury was observed in fish. Electron microscopy and x-ray microanalysis revealed mineral granules consisting of clustered crystalline particles in toothed cetaceans, sea lions and cormorants but not in tuna and swordfish. Granules containing mercury and selenium were mainly located in the cytoplasm of macrophages. These results suggest that the biosynthesis of mineral granules containing mercury and selenium in top marine predators is a common feature among these animals and that the existence of elimination pathways for the excretion of organic mercury might influence the amount of mercury and selenium stored as mineral granules in a particular species.
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This paper reviews the growing literature dealing with the antagonistic effect of selenium (Se) compounds on the toxicity of mercury (Hg) compounds in higher animals and organisms present in the aquatic environment. It covers both laboratory and field studies and summarizes the possible mechanisms that explain the protective action of Se compounds on mercuric mercury (Hg2+) and methylmercury (CH3Hg+) toxicity. The review is subdivided according to the molecular form of Hg and the organisms in which the antagonism has been studied. Many authors suggest that the protective effect of selenite on the toxicity of Hg2+ in mammals is due mainly to the in vivo formation of mercuric selenide (HgSe), a stable and biologically inert complex. The detection of HgSe has been confirmed in several studies in support of this mechanism. Possible mechanisms that may be involved in the antagonism between Se compounds and CH3Hg+ in mammals and aquatic organisms are also presented. The possibility of adding Se compounds to contaminated lakes and reservoirs as a remediation technique to limit the bioaccumulation of Hg2+ and CH3Hg+ is critically discussed.
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The concentrations of total mercury in muscle (17 samples), liver (16 samples) and kidney tissues (16 samples) of both bottlenose (Tursiops truncatus) and striped dolphins (Stenella coeruloalba) were analyzed by cold vapour atomic absorption (AA) spectroscopy. The dolphins were found dead at different locations along the east Adriatic over a 10-year period starting in 1990. In this study, the magnitude of mercury contamination of dolphins which are indicators of contamination of the Adriatic as well as the Mediterranean Sea was determined. Our results represent the first investigation of heavy metal concentrations in dolphins sampled along the Croatian coast of the Adriatic Sea. Total mercury levels were high, ranging from 1.51 to 136.7 mg/kg in muscle, from 2.04 to 143.1 in kidney and from 10.35 to 1 833 mg/kg in liver tissues (expressed as wet weight). These results were examined for differences based upon age and tissue type. A high correlation was observed between total mercury concentration and age, and adult dolphins (10 samples) contained statistically significant higher concentrations of mercury compared to juvenile (seven samples) dolphins. Mercury concentrations were generally the highest in liver tissue. The presence of high mercury levels in dolphins is attributed to natural as well as anthropogenic sources.
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Mercury is a toxic metallic element that is known to bioaccumulate in many marine organisms. Mercury concentrations are routinely evaluated in Indian River Lagoon (IRL) fish, however, there are no published reports of these concentrations for IRL bottlenose dolphins, Tursiops truncatus (Montagu, 1821). Muscle (n = 30) and liver (n = 19) samples from stranded IRL dolphins were collected and analyzed for total mercury and selenium. Total mercury concentrations in liver samples ranged from 0.42 to 240 ppm wet weight (ww) (mean = 73.01 ppm) and concentrations in muscle samples ranged from 0.26 to 47 ppm ww (mean = 5.68 ppm). Mercury concentrations were not significantly different between males and females for both tissue types. Selenium concentrations ranged from 1.20 to 90.70 ppm ww (mean = 29.81 ppm) in liver tissue and 0.75 to 16.10 ppm ww (mean = 1.92 ppm) in muscle tissue. Selenium concentrations were positively correlated with mercury in both tissue types. Age and total length were good predictors for mercury concentrations in both tissue types. Future studies are needed to determine what effect mercury may have on the overall health of IRL dolphins.
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Mercury (Hg) contamination from a variety of point and non-point sources, including atmospheric inputs, is currently considered to be the most serious environmental threat to the well being of fish and wildlife resources in the southeastern United States. Fish consumption advisories have been issued in all ten states comprising the U.S. Fish and Wildlife Service's Southeast Region. Both freshwater and marine species have been affected with levels ranging as high as 7.0 ppm in some individuals. Many other species, including various species of reptiles, birds and mammals (including humans) are also contaminated. Impacts noted range from reproductive impairment to mortality.
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Bottlenose dolphins (Tursiops truncatus), as long-lived, long-term residents of bays, sounds, and estuaries, can serve as important sentinels of the health of coastal marine ecosystems. As top-level predators on a wide variety of fishes and squids, they concentrate contaminants through bioaccumulation and integrate broadly across the ecosystem in terms of exposure to environmental impacts. A series of recent large-scale bottlenose dolphin mortality events prompted an effort to develop a proactive approach to evaluating risks by monitoring living dolphin populations rather than waiting for large numbers of carcasses to wash up on the beach. A team of marine mammal veterinarians and biologists worked together to develop an objective, quantitative, replicable means of scoring the health of dolphins, based on comparison of 19 clinically diagnostic blood parameters to normal baseline values. Though the scoring system appears to roughly reflect dolphin health, its general applicability is hampered by interlaboratory variability, a lack of independence between some of the variables, and the possible effects of weighting variables. High score variance seems to indicate that the approach may lack the sensitivity to identify trends over time at the population level. Potential solutions to this problem include adding or replacing health parameters, incorporating only the most sensitive measures, and supplementing these with additional measures of health, body condition, contaminant loads, or biomarkers of contaminants or their effects that can also be replicated from site to site. Other quantitative approaches are also being explored.
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To conduct health assessments and compare outcomes in 2 populations of Atlantic bottlenose dolphins. Design-Repeated cross-sectional study. 171 Atlantic bottlenose dolphins. During June and August of 2003 through 2005, 89 dolphins from the Indian River Lagoon (IRL), Florida, and 82 dolphins from estuarine waters near Charleston, SC, were evaluated. A panel of 5 marine mammal veterinarians classified dolphins as clinically normal, possibly diseased, or definitely diseased on the basis of results of physical and ultrasonographic examinations, hematologic and serum biochemical analyses, and cytologic and microbiologic evaluations of gastric contents and swab specimens. Prevalence of dolphins classified as definitely diseased did not differ significantly between the IRL (32%) and Charleston (20%) sites. Proportions of dolphins classified as possibly diseased also did not differ. Lobomycosis was diagnosed in 9 dolphins from the IRL but in none of the dolphins from Charleston. Proportions of dolphins with orogenital papillomas did not differ significantly between the IRL (12%) and Charleston (7%) sites. From 2003 through 2005, the proportion classified as definitely diseased tripled among dolphins from the Charleston site but did not increase significantly among dolphins from the IRL. Dolphins from the Charleston site were more likely to have leukocytosis, lymphocytosis, and low serum concentrations of total protein and total J-globulins than were dolphins from the IRL. High prevalences of diseased dolphins were identified at both sites; however, the host or environmental factors that contributed to the various abnormalities detected are unknown.
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Biological samples of free-ranging dolphins are increasingly used to gain information on population structure and ecology. In small cetaceans, the gender of individuals usually cannot be determined at sea, and population sex ratio has to be inferred indirectly. We used molecular sexing to determine the gender of 340 biopsy samples of bottlenose dolphins, Tursiops truncatus, spotted dolphins, Stenella frontalis, and common dolphins, Delphinus delphis, collected around the Azores and Madeira. Sex ratio was globally skewed in favor of males, and differed between species and archipelagos. Skew was probably influenced by the selectivity of biopsy collectors and seasonal or year-round predominance of males in natural populations. Skew was also influenced by sampling duration and intensity. In the Azores, when several samples were successively collected within the same group, the proportion of female samples decreased as a function of sample order. This trend indicated a tendency for females to increasingly avoid the boat while samples were being collected. It showed that males and females reacted differently to the perturbation caused by the biopsy sampling process (i.e., sample collection and driving style).
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Polychlorinated biphenyls (PCBs), chlorinated pesticides (i.e., dichlorodiphenyltrichloroethane (DDT) and its metabolites, chlordanes (CHLs), dieldrin, hexachlorobenzene (HCB), and mirex), polybrominated diphenyl ethers (PBDEs), perfluorinated chemicals (PFCs), and polyaromatic hydrocarbons (PAHs) were measured in blubber biopsy samples collected from 139 wild bottlenose dolphins (Tursiops truncatus) during 2003-2005 in Charleston (CHS), SC and the Indian River Lagoon (IRL), FL. Dolphins accumulated a similar suite of contaminants with summation operatorPCB dominating (CHS 64%, IRL 72%), followed by summation operatorDDT (CHS 20%, IRL 17%), summation operatorCHLs (CHS 7%; IRL 7%), summation operatorPBDE (CHS 4%, IRL 2%), PAH at 2%, and dieldrin, PFCs and mirex each 1% or less. Together summation operatorPCB and summation operatorDDT concentrations contributed approximately 87% of the total POCs measured in blubber of adult males. summation operatorPCBs in adult male dolphins exceed the established PCB threshold of 17mg/kg by a 5-fold order of magnitude with a 15-fold increase for many animals; 88% of the dolphins exceed this threshold. For male dolphins, CHS (93,980ng/g lipid) had a higher summation operatorPCBs geomean compared to the IRL (79,752ng/g lipid) although not statistically different. In adult males, the PBDE geometric mean concentration was significantly higher in CHS (5920ng/g lipid) than the IRL (1487ng/g). Blubber summation operatorPFCs concentrations were significantly higher in CHS dolphins. In addition to differences in concentration of PCB congeners, summation operatorPBDE, TEQ, summation operatorCHLs, mirex, dieldrin, and the ratios summation operatorDDE/ summation operatorDDT and trans-nonachlor/cis-nonachlor were the most informative for discriminating contaminant loads in these two dolphin populations. Collectively, the current summation operatorPCB, summation operatorDDT, and summation operatorPBDEs blubber concentrations found in CHS dolphins are among the highest reported values in marine mammals. Both dolphin populations, particularly those in CHS, carry a suite of organic chemicals at or above the level where adverse effects have been reported in wildlife, humans, and laboratory animals warranting further examination of the potential adverse effects of these exposures.
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The human immune response to mercury is not well characterized despite the body of evidence that suggests that Hg can modulate immune responses, including the induction of autoimmune disease in some mouse models. Dysregulation of cytokine signaling appears to play an important role in the etiology of Hg-induced autoimmunity in animal models. In this study, we systematically investigated the human immune response to Hg in vitro in terms of cytokine release. Human peripheral blood mononuclear cells (PBMCs) were isolated from 20 volunteers who donated blood six separate times. PBMCs were cultured with lipopolysaccharide and concentrations of mercuric chloride (HgCl(2)) up to 200 nM. Seven cytokines representing important pathways in physiologic and pathologic immune responses were measured in supernatants. We used multilevel models to account for the intrinsic clustering in the cytokine data due to experimental design. We found a consistent increase in the release of the proinflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha, and concurrent decrease in release of the antiinflammatory cytokines interleukin 1-receptor antagonist (IL-1Ra) and IL-10 in human PBMCs treated with subcytotoxic concentrations of HgCl(2). IL-4, IL-17, and interferon-gamma increased in a concentration-response manner. These results were replicated in a second, independently recruited population of 20 different volunteers. Low concentrations of HgCl(2) affect immune function in human cells by dysregulation of cytokine signaling pathways, with the potential to influence diverse health outcomes such as susceptibility to infectious disease or risk of autoimmunity.
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Many of the remaining members of the endangered Florida panther (Felis concolor coryi) population suffer from one or more of a variety of physiological, reproductive, endocrine, and immune system defects including congenital heart defects, abnormal sperm, low sperm density, cryptorchidism, thyroid dysfunction, and possible immunosuppression. Mercury contamination, determined to be the cause of death of a female panther in 1989, was presented as the likely cause of thyroid dysfunction. As genetic diversity in the species was less than expected, all of the other abnormalities have been attributed to inbreeding. However, exposure to a variety of chemical compounds, especially those that have been identified as environmental endocrine disrupters (including mercury, p,p'-DDE, and polychlorinated biphenyls), has elicited all of the listed abnormalities in other species. A number of these contaminants are present in South Florida. An exposure pathway has been identified, and evidence presented in this paper, including the fact that there appears to be no significant difference between serum estradiol levels in males and females, suggests that many male panthers may have been demasculinized and feminized as a result of either prenatal or postnatal exposure. Thus, regardless of the effects of inbreeding, current evidence seems to indicate that environmental contaminants may be a major factor contributing to reproductive impairment in the Florida panther population.
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Eighteen stranded Atlantic bottlenose dolphins (Tursiops truncatus) examined postmortem were sampled for histologic study. All cases were examined for ferric ion and lipofuscin. Ages were determined from tooth growth layers. Electron microscopic (EM) examination and X-ray spectroscopy (EDAX) were performed. Chemical analysis for mercury was conducted on 12 of the animals by atomic absorption spectrophotometry. Nine animals were found to have excessive lipofuscin in both liver and kidney. Four of these nine animals also exhibited active liver disease (fat globules, central necrosis, lymphocytic infiltrates) whereas, of the animals without the excessive pigment, only one animal had an active liver lesion. EM and EDAX showed electron-dense amorphous material presumably within lysosomes to be Hg with no deposits on mitochondrial or nuclear membranes noted. Age relationship to portal pigment deposition was positive. Liver mercury concentrations ranged from 0.01 to 443 micrograms/g of wet weight with all animals having liver pigment yielding values of or above 61 micrograms/g, whereas all animals lacking pigment had values of or below 50 micrograms/g. The evidence suggests that the excessive pigment accumulation is related to toxic effects of Hg and presents as increased active liver disease.