Tissue-specific distribution and whole-body burden estimates of persistent organic pollutants in the bottlenose dolphin (Tursiops truncatus)

Marine Biomedicine and Environmental Sciences Center, Medical University of South Carolina, 221 Fort Johnson Rd., Charleston, South Carolina 29412, USA.
Environmental Toxicology and Chemistry (Impact Factor: 3.23). 06/2010; 29(6):1263-73. DOI: 10.1002/etc.152
Source: PubMed


Most exposure assessments for free-ranging cetaceans focus on contaminant concentrations measured in blubber, and few data are available for other tissues or the factors governing contaminant distribution among tissues. The goal of this study was to provide a detailed description of the distribution of persistent organic pollutants (POPs) within the common bottlenose dolphin (Tursiops truncatus) body and assess the role of lipid dynamics in mediating contaminant distribution. Thirteen tissues (brain, blubber, heart, liver, lung, kidney, mammary gland, melon, skeletal muscle, spleen, thyroid, thymus, and testis/uterus) were sampled during necropsy from bottlenose dolphins (n = 4) and analyzed for lipid and 85 POPs, including polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers. Significant correlations between tissue POP concentrations and lipid suggest that distribution of POPs is generally related to tissue lipid content. However, blubber:tissue partition coefficients ranged widely from 0.753 to 6.25, suggesting that contaminant distribution is not entirely lipid-dependent. Tissue-specific and whole-body contaminant burdens confirmed that blubber, the primary site of metabolic lipid storage, is also the primary site for POP accumulation, contributing >90% to the whole-body burdens. Observations also suggest that as lipid mobilizes from blubber, contaminants may redistribute, leading to elevated tissue concentrations. These results suggest that individuals with reduced blubber lipid may be at increased risk for exposure-related health effects. However, this study also provides evidence that the melon, a metabolically inert lipid-rich structure, may serve as an alternate depot for POPs, thus preventing the bulk of blubber contaminants from being directly available to other tissues. This unique physiological adaptation should be taken into consideration when assessing contaminant-related health effects in wild cetacean populations.

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Available from: John R Kucklick, Dec 19, 2013
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    • "Marine mammal blubber is a modified form of adipose tissue functioning primarily as a site for metabolic energy storage and plays an important physiological role in streamlining, thermoregulation , and buoyancy (Pabst et al., 1999). Blubber is the primary site for accumulation of lipophilic OCs, containing 70e95% of a marine mammals whole body burden (Tanabe et al., 1981; Yordy et al., 2010). Consequently, non-lethal biopsying of the blubber tissue has formed the basis for most OC toxicological biomonitoring assessments of wild cetaceans. "
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    ABSTRACT: Persistent Organic Pollutants (POPs), such as toxic lipophilic organochlorine (OC) compounds, accumulate in the blubber tissue of marine mammals. Toxicological sampling methods most frequently target only the superficial blubber layer. Vertical distribution of these contaminants through the blubber mantle may, however, not be homogenous and could reflect any dissemination of lipids and fatty acids (FAs). It is therefore critical to assess stratification patterns in a species of interest as a quality control measure for interpretation of toxicological data. Here, we analyzed and compared the distribution of lipids, FAs, and OCs in the outermost and innermost blubber layer of southern hemisphere humpback whales. FA stratification was evident for short-chain (≤ 18) monounsaturated fatty acids (SC-MUFA), which were concentrated in the outer layer, consistent with the thermoregulatory role of this blubber layer. This stratification was, however, not reflected in OC distribution, which was similar in the inner and outer blubber layers of male humpback whales. By comparison, a noticeable gradient in total blubber lipid from the outer to the inner layer was observed in two lactating females, which coincided with higher lipid normalised contaminant levels in the inner layer. This study contains the most comprehensive assessment of humpback whale blubber stratification to date, however, further investigation of biological and ecological influencing factors is required.
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    • "High levels of POPs have been found in both abiotic and biotic matrices in the PRE (Guan et al., 2007; Guo et al., 2008, 2009; Wu et al., 2013). Legacy POPs, including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), have adversely affected the reproduction and immune functions (Lahvis et al., 1995), decreased the offspring survivorship (Schwacke et al., 2002) and depressed the population growth rates (Wells et al., 2005) of cetaceans elsewhere in the world, which threaten the health and population sustainability of cetaceans (Yordy et al., 2010a). Studies of the potential health risks of POPs as the major organic contaminants in the marine ecosystem are therefore essential for better conservation and management of Indo-Pacific Humpback dolphins. "
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    ABSTRACT: Indo-Pacific humpback dolphins (Sousa chinensis) are apex predators in the Pearl River Estuary waters (PRE) of China. PCBs, DDTs and other organochlorine pesticides (OCPs) (e.g., HCHs, HCB, mirex and dieldrin) were analysed in blubber samples of 45 dolphins and 10 prey fishes of S. chinensis collected from 2004 to 2013 in the PRE region to investigate the bioaccumulation and potential biomagnification of persistent organic pollutants (POPs). DDTs were the most abundant residue in the dolphins, with an average of 62700ngg(-1) wet weight (ww), followed by PCBs (average: 1790ngg(-1) ww) and other OCPs including ∑HCHs, mirex, endrin, ∑chlordanes, HCB, dieldrin, aldrin, heptachlor, and pentachlorobenzene. The concentrations of PCBs and DDTs in male dolphins significantly increased with age and length. In contrast, female dolphins did not show obvious bioaccumulation trends with age and body length, possibly due to the lactational and parturitional transfer of these compounds. Compared with the POP residues in the prey fishes, the concentrations of PCBs, DDTs, and HCHs in the dolphin blubber increased by factors of 99, 212, and 5, respectively, whereas the residue levels of the other OCPs increased 2-185 times, indicating a potentially significant biomagnification in the top predators. The potential biomagnification factors calculated for most POPs were significantly higher than those in the cetacean species from other regions.
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    • "T.t. 9 18 9 578.6 ± 362.4 209.0 ± 170.9 149.9 ± 77.0 246.9 ± 153.1 91.2 ± 100.8 60.3 ± 55.9 Borrell and Aguilar, 2007 Eastern Italian coast, 1999–2000 T.t. 9 32.7 ± 16.9 Storelli and Marcotrigiano, 2003 Gran Canaria, Spain T.t. 1 11.0 a 15.6 a Jaber et al., 2005 Sarasota Bay, Florida, 2000–2005 T.t. 16 31 98.6 ± 159 (adult male) 4.7 ± 5.4 (adult female) 51.5 ± 123 1.3 ± 3.1 Yordy et al., 2010 Taiwan coastal waters, 2000–2001 T.t. 6 5.4 ± 3.6 a Chou et al., 2004 Coastal Georgia, USA, 2004 T.t. "
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    ABSTRACT: Levels of 24 organochlorine compounds, including toxic mono-ortho PCB congeners, were determined in the organs and tissues (blubber, kidney, lung, muscle, liver, heart) of 13 common bottlenose dolphins (Tursiops truncatus) stranded between 2000 and 2005 in the northern part of the Croatian territorial waters of the Adriatic Sea. Polychlorinated biphenyls (PCBs) were found at higher concentrations in comparison with organochlorine pesticides (OCPs) in all of the analysed tissues. Sums of six indicator congeners (Σ6PCB) constituted around 50 % of the total PCB amount, while PCB-153 and PCB-138 were found to have the highest concentrations. Among the seven investigated OCPs, p,ṕ-DDE was found at the highest concentrations. In blubber, mean values of 22048 and 11310 ng g−1 wet weight were determined for ΣPCB and ΣDDT, respectively. Much lower concentrations were found in muscle samples, followed by similar concentrations in kidneys, liver and heart, while the lowest levels of organochlorine contaminants were found in lungs. The results indicate that p,p’-DDT is still being introduced in the Mediterranean region. PCB concentrations are among the highest found in this region and toxicological assessments indicate that the health of this specie is at high risk.
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