Polychlorinated biphenyl and polybrominated diphenyl ether profiles vary with feeding ecology and marine rearing distribution among 10 Chinook salmon (Oncorhynchus tshawytscha) stocks in the North Pacific Ocean.

Chinook salmon (Oncorhynchus tshawytscha) along the west coast of North America have experienced significant declines in abundance and body size over recent decades due to several anthropogenic stressors. Understanding the reasons underlying the relatively high levels of persistent organic pollutants (POPs) in Chinook stocks is an important need, as it informs recovery planning for this foundation species, as well for the Chinook-dependent Resident killer whales (Orcinus orca, RKW) of British Columbia (Canada) and Washington State (USA). We evaluated the influence of stock-related differences in feeding ecology, using stable isotopes, and marine rearing ground on the concentrations and patterns of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Chinook salmon. A principal components analysis (PCA) revealed a clear divergence of PCB and PBDE congener patterns between Chinook with a nearshore rearing distribution ('shelf resident') versus a more offshore distribution. Shelf resident Chinook had 12-fold higher PCB concentrations and 46-fold higher PBDE concentrations relative to offshore stocks. Shelf resident Chinook had PCB and PBDE profiles that were heavier and dominated by more bioaccumulative congeners, respectively. The higher δ13C and δ15N in shelf resident Chinook compared to the offshore rearing stocks, and their different marine distributions explain the large divergence in contaminant levels and profiles, with shelf resident stocks being heavily influenced by land-based sources of industrial contamination. Results provide compelling new insight into the drivers of contaminant accumulation in Chinook salmon, raise important questions about the consequences for their health, and explain a major pathway to the heavily POP-contaminated Resident killer whales that consume them.

Water and sediment as sources of phosphate in aquatic ecosystems: The Detroit River and its role in the Laurentian Great Lakes.

Eutrophication of freshwater ecosystems and harmful algal blooms (HABs) are an ongoing concern affecting water quality in the Great Lakes watershed of North America. Despite binational management efforts, Lake Erie has been at the center of dissolved reactive phosphate driven eutrophication research due to its repeated cycles of algae blooms. We investigated the Detroit River, the largest source of water entering Lake Erie, with the objectives to (1) characterize Detroit River phosphate levels within water and sediment, and (2) use multiple chemical and isotopic tracers to identify nutrient sources in the Detroit River. Riverine water and sediment samples were collected at 23 locations across 8 transects of the Detroit River. The bulk δ15N values from sediments were enriched compared the δ15N values of nitrate from water samples, consistent with biogeochemical cycling in the sediment. Principle component analysis of multiple chemical tracers from water samples found spatial variation consistent with multiple sources including synthetic and manure-derived fertilizers and wastewater effluent. The concentrations of phosphate dissolved in water were within regulatory guidelines; however, sediments had elevated concentrations of both water- and acid-extractable phosphate. Sediment-sequestered legacy phosphorus historically deposited in the Detroit River may be transported into Lake Erie and, if mobilized into the water column, be an unrecognized internal-load that contributes to algal bloom events. Globally, freshwater ecosystems are impacted by numerous non-point source phosphorus inputs contributing to eutrophication and the use of multiple tracer approaches will increase our ability to effectively manage aquatic ecosystems.

A field test of the use of pop-off data storage tags in freshwater fishes.

In the present study, pop-off data storage tags (pDST) without any transmitting capabilities were attached to 118 adult salmonids in a 19 000 km2 freshwater system (Lake Ontario). The 9·3 cm long cylindrical tags were externally attached to fishes using a backpack-style harness, set to record pressure (dBar ≈ depth in m) and temperature every 70 s (and at some key times, every 5 s) and programmed to release from the harness and float to the surface after c. 1 year. Recapture of the bright-orange tags for data retrieval relied on members of the public finding tags on shore, or on anglers capturing fishes with tags attached and using the contact information displayed on each tag to mail tags to the research team in exchange for a monetary reward. Thirty-seven tags were found and returned from the 118 released (31%), while 26 of the 118 tags (22%) remained scheduled to pop-off in summer 2017. Of the 37 tags returned, 23 were from wild-caught fishes (out of 88 wild-caught and tagged fishes; 26%) and yielded useful data whereas 14 were from hatchery-reared fishes that were opportunistically tagged and appear to have been unable to acclimate to life in the wild and died days to weeks after release. The field study described here thus demonstrated that pDSTs can be a viable option for collecting large amounts of high-resolution depth and temperature data for salmonids in freshwater systems. Technical challenges, limitations and unknowns related to the use of pDSTs with freshwater fishes are discussed. In addition, pDSTs are compared with alternate electronic tagging technologies and assessed for their potential as a more widespread tool in research on freshwater fishes.

Tissue-specific turnover and diet-tissue discrimination factors of carbon and nitrogen isotopes of a common forage fish held at two temperatures.

RATIONALE: The application of stable isotopes to foraging ecology is dependent on understanding life-history and environmental factors unrelated to diet that may influence isotopic composition. Diet-tissue discrimination factors (DTDFs) and turnover rates will increase the accuracy of isotope-based studies. Furthermore, little consideration has been given to the effects of temperature or life-history stage on isotopic ratios despite the prevalence of variation in temperature and growth rates throughout life. METHODS: We measured δ13 C and δ15 N values with an elemental analyzer coupled to a continuous flow isotope ratio mass spectrometer. These values were used to estimate turnover and DTDFs for Emerald Shiners (Notropis atherinoides), a common North American freshwater forage fish. Fish were assigned to a temperature treatment, either 10°C (Low) or 20°C (High), and provided one of three diets (commercial pellet, Artemia salina, or Hemimysis anomala). At regular intervals fish were sampled and the isotopic compositions of whole body and liver tissues were determined. RESULTS: Tissue turnover rates for fish fed Artemia were faster for liver than for whole body, but were also influenced by temperature. Turnover occurred faster at higher temperatures for body and liver δ15 N values, but not for δ13 C values. The pellet and Hemimysis treatments were in isotopic equilibrium from the start of the experiment and estimated DTDFs based on these treatments were lower than assumed for Δ15 N (+0.6 to 2.7‰) and variable, but within expected ranges for Δ13 C (-1.9 to +1.5‰). CONCLUSIONS: The results for Emerald Shiners differed from commonly made assumptions for applying stable isotopes to ecological questions, possibly related to a bias in the use of juveniles in studies of turnover and DTDFs and assumptions regarding thermal-independence of isotopic relationships. The species-specific DTDF and tissue turnover estimates provided here will inform interpretations of stable isotope data for smaller fish species and improve food-web studies.

Diet-tissue discrimination factors and turnover of carbon and nitrogen stable isotopes in tissues of an adult predatory coral reef fish, Plectropomus leopardus.

RATIONALE: Stable isotope ratios (δ(13)C and δ(15)N values) provide a unique perspective into the ecology of animals because the isotope ratio values of consumers reflect the values in food. Despite the value of stable isotopes in ecological studies, the lack of species-specific experimentally derived diet-tissue discrimination factors (DTDFs) and turnover rates limits their application at a broad scale. Furthermore, most aquatic feeding experiments use temperate, fast-growing fish species and few have considered medium- to large-sized adults with low growth rates from tropical ecosystems. METHODS: A controlled-diet stable isotope feeding trial was conducted over a 196-day period for the adult predatory reef fish leopard coralgrouper (Plectropomus leopardus). This study calculated δ(13)C and δ(15)N DTDFs and turnover rates in five tissues (liver, plasma, red blood cells (RBC), fin, and muscle) using a continuous flow isotope ratio mass spectrometer equipped with an elemental analyzer. In addition, the effect of chemical lipid extraction (LE) on stable isotope values was examined for each tissue. RESULTS: Turnover was mainly influenced by metabolism (as opposed to growth) with LE δ(15)N half-life values lowest in fin (37 days) and plasma (66 days), and highest in RBC (88 days) and muscle (126 days). The diet-tissue discrimination factors for δ(15)N values in all tissues (Δ(15)N: -0.15 to 1.84‰) were typically lower than commonly reported literature values. Lipid extraction altered both δ(15) N and δ(13)C values compared with untreated samples; however, for the δ(15)N values, the differences were small (mean δ(15)N(LE-Bulk) <0.46‰ in all tissues). CONCLUSIONS: This study informs future interpretation of stable isotope data for medium- to large-sized fish and demonstrates that DTDFs developed for temperate fish species, particularly for δ(15)N values, may not apply to tropical species. Sampling of muscle and/or RBC is recommended for a relatively long-term representation of feeding habits, while plasma and/or fin should be used for a more recent indication of diet.

Regional movement patterns of a small-bodied shark revealed by stable-isotope analysis.

This study used stable-isotope analysis to define the nearshore regional residency and movements of the small-bodied Australian sharpnose shark Rhizoprionodon taylori. Plasma and muscle δ(13) C and δ(15) N of R. taylori were collected from across five embayments and compared with values of seagrass and plankton from each bay. Linear distances between adjacent bays ranged from 30 to 150 km. There was a positive geographic correlation between R. taylori tissue and environmental δ(13) C values. Populations with the highest tissue δ(15) N were collected from bays that had the highest environmental δ(15) N values. These results suggest that R. taylori did not forage more than 100 km away from their capture location within 6 months to 1 year. The successful application of isotope analysis to define R. taylori movement demonstrates that this technique may be used in addition to traditional methods to study the movement of sharks, even within similar habitats across regionally small spatial scales (<100 km).

Biology of the Greenland shark Somniosus microcephalus.

Greenland shark Somniosus microcephalus is a potentially important yet poorly studied cold-water species inhabiting the North Atlantic and Arctic Oceans. Broad-scale changes in the Arctic ecosystem as a consequence of climate change have led to increased attention on trophic dynamics and the role of potential apex predators such as S. microcephalus in the structure of Arctic marine food webs. Although Nordic and Inuit populations have caught S. microcephalus for centuries, the species is of limited commercial interest among modern industrial fisheries. Here, the limited historical information available on S. microcephalus occurrence and ecology is reviewed and new catch, biological and life-history information from the Arctic and North Atlantic Ocean region is provided. Given the considerable by-catch rates in high North Atlantic Ocean latitudes it is suggested that S. microcephalus is an abundant predator that plays an important, yet unrecognized, role in Arctic marine ecosystems. Slow growth and large pup sizes, however, may make S. microcephalus vulnerable to increased fishing pressure in a warming Arctic environment.

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions.

Stable-isotope analysis (SIA) can act as a powerful ecological tracer with which to examine diet, trophic position and movement, as well as more complex questions pertaining to community dynamics and feeding strategies or behaviour among aquatic organisms. With major advances in the understanding of the methodological approaches and assumptions of SIA through dedicated experimental work in the broader literature coupled with the inherent difficulty of studying typically large, highly mobile marine predators, SIA is increasingly being used to investigate the ecology of elasmobranchs (sharks, skates and rays). Here, the current state of SIA in elasmobranchs is reviewed, focusing on available tissues for analysis, methodological issues relating to the effects of lipid extraction and urea, the experimental dynamics of isotopic incorporation, diet-tissue discrimination factors, estimating trophic position, diet and mixing models and individual specialization and niche-width analyses. These areas are discussed in terms of assumptions made when applying SIA to the study of elasmobranch ecology and the requirement that investigators standardize analytical approaches. Recommendations are made for future SIA experimental work that would improve understanding of stable-isotope dynamics and advance their application in the study of sharks, skates and rays.

Persistent organic pollutants and mercury in marine biota of the Canadian Arctic: an overview of spatial and temporal trends.

This review summarizes and synthesizes the significant amount of data which was generated on mercury (Hg) and persistent organic pollutants (POPs) in Canadian Arctic marine biota since the first Canadian Arctic Contaminants Assessment Report (CACAR) was published in 1997. This recent body of work has led to a better understanding of the current levels and spatial and temporal trends of contaminants in biota, including the marine food species that northern peoples traditionally consume. Compared to other circumpolar countries, concentrations of many organochlorines (OCs) in Canadian Arctic marine biota are generally lower than in the European Arctic and eastern Greenland but are higher than in Alaska, whereas Hg concentrations are substantially higher in Canada than elsewhere. Spatial coverage of OCs in ringed seals, beluga and seabirds remains a strength of the Arctic contaminant data set for Canada. Concentrations of OCs in marine mammals and seabirds remain fairly consistent across the Canadian Arctic although subtle differences from west to east and south to north are found in the proportions of various chemicals. The most significant development since 1997 is improvement in the temporal trend data sets, thanks to the use of archived tissue samples from the 1970s and 1980s, long-term studies using archeological material, as well as the continuation of sampling. These data cover a range of species and chemicals and also include retrospective studies on new chemicals such as polybrominated diphenyl ethers. There is solid evidence in a few species (beluga, polar bear, blue mussels) that Hg at some locations has significantly increased from pre-industrial times to the present; however, the temporal trends of Hg over the past 20-30 years are inconsistent. Some animal populations exhibited significant increases in Hg whereas others did not. Therefore, it is currently not possible to determine if anthropogenic Hg is generally increasing in Canadian Arctic biota. It is also not yet possible to evaluate whether the recent Hg increases observed in some biota may be due solely to increased anthropogenic inputs or are in part the product of environmental change, e.g., climate warming. Concentrations of most "legacy" OCs (PCBs, DDT, etc.) significantly declined in Canadian Arctic biota from the 1970s to the late 1990s, and today are generally less than half the levels of the 1970s, particularly in seabirds and ringed seals. Chlorobenzenes and endosulfan were among the few OCs to show increases during this period while summation operatorHCH remained relatively constant in most species. A suite of new-use chemicals previously unreported in Arctic biota (e.g., polybrominated diphenyl ethers (PBDEs), short chain chlorinated paraffins (SCCPs), polychlorinated naphthalenes (PCNs), perfluoro-octane sulfonic acid (PFOS) and perfluorocarboxylic acids (PFCAs)) has recently been found, but there is insufficient information to assess species differences, spatial patterns or food web dynamics for these compounds. Concentrations of these new chemicals are generally lower than legacy OCs, but there is concern because some are rapidly increasing in concentration (e.g., PBDEs), while others such as PFOS have unique toxicological properties, and some were not expected to be found in the Arctic because of their supposedly low potential for long-range transport. Continuing temporal monitoring of POPs and Hg in a variety of marine biota must be a priority.

Trophic transfer of persistent organochlorine contaminants (OCs) within an Arctic marine food web from the southern Beaufort-Chukchi Seas.

Stable isotope values (13C, 15N) and concentrations of persistent organochlorine contaminants (OCs) were determined to evaluate the near-shore marine trophic status of biota and biomagnification of OCs from the southern Beaufort-Chukchi Seas (1999-2000) near Barrow, AK. The biota examined included zooplankton (Calanus spp.), fish species such as arctic cod (Boreogadus saida), arctic char (Salvelinus alpinus), pink salmon (Oncorhynchus gorbuscha), and fourhorn sculpin (Myoxocephalus quadricornis), along with marine mammals, including bowhead whales (Balaena mysticetus), beluga whales (Delphinapterus leucas), ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). The isotopically derived trophic position of biota from the Beaufort-Chukchi Seas marine food web, avian fauna excluded, is similar to other coastal food webs in the Arctic. Concentrations of OCs in marine mammals were significantly greater than in fish and corresponded with determined trophic level. In general, OCs with the greatest food web magnification factors (FWMFs) were those either formed due to biotransformation (e.g. p,p'-DDE, oxychlordane) or considered recalcitrant (e.g. -HCH, 2,4,5-Cl substituted PCBs) in most biota, whereas concentrations of OCs that are considered to be readily eliminated (e.g. -HCH) did not correlate with trophic level. Differences in physical-chemical properties of OCs, feeding strategy and possible biotransformation were reflected in the variable biomagnification between fish and marine mammals. The FWMFs in the Beaufort-Chukchi Seas region were consistent with reported values in the Canadian Arctic and temperate food webs, but were statistically different than FWMFs from the Barents and White Seas, indicating that the spatial variability of OC contamination in top-level marine Arctic predators is attributed to differences in regional sources of contamination rather than trophic position.

Persistent organochlorine contaminants and enantiomeric signatures of chiral pollutants in ringed seals (Phoca hispida) collected on the east and west side of the Northwater Polynya, Canadian Arctic.

To examine the influence of diet and age on organochlorine contaminant (OC) concentrations in two closely related ringed seal (Phoca hispida) populations enantiomeric fractions (EFs) of chiral contaminants and stable isotopes of nitrogen (delta15N) and carbon (delta13C) were measured along with OCs in ringed seals collected from the east and west side of the Northwater Polynya. Seals from these two locations were feeding at the same trophic level based on delta15N values in muscle but had slightly different sources of carbon based on delta13C measurements in muscle. After removing the influence of age, sex, and blubber thickness, OC concentrations did not vary between ringed seals from the east and west side of the polynya. SigmaPCB, SigmaDDT, and Sigmachlordane were found to increase with age for both male and female seals. The inclusion of older (>20 years) female seals, which may have a reduced reproductive effort, may influence the relationships in females. Stable isotopes failed to describe OC concentrations in ringed seals suggesting that diet was not a major factor in variation of OC concentrations within this ringed seal population. Cis- and trans-chlordane, oxychlordane, and heptachlor epoxide were all nonracemic in the ringed seal blubber but did not vary with age, sex, or collection site. Alpha-HCH appeared racemic (enantiomeric fraction = 0.50 +/- 0.01) in the seals, although this EF is different than those previously observed in their prey species, and was found to vary significantly with age. EF values in the ringed seals varied considerably from other Arctic marine mammals and seabirds, providing addition evidence that the type(s) and characteristic(s) of the enzymes involved in biotransformation of chiral OCs vary between these organisms.

Persistent organic pollutants (POPs) in a small, herbivorous, arctic marine zooplankton (Calanus hyperboreus): trends from April to July and the influence of lipids and trophic transfer.

Samples of Calanus hyperboreus, a herbivorous copepod, were collected (n = 20) between April and July 1998, and water samples (n = 6) were collected in May 1998, in the Northwater Polynya (NOW) to examine persistent organic pollutants (POPs) in a high Arctic marine zooplankton. Lipid content (dry weight) doubled, water content (r2 = 0.88) and delta15N (r2 = 0.54) significantly decreased, and delta13C significantly increased (r2 = 0.30) in the C. hyperboreus over the collection period allowing an examination of the role of these variables in POP dynamics in this small pelagic zooplankton. The rank and concentrations of POP groups in C. hyperboreus over the entire sampling was sum of PCB (30.1 +/- 4.03 ng/g, dry weight) > sum of HCH (11.8 +/- 3.23) > sum of DDT (4.74 +/- 0.74), sum of CHLOR (4.44 +/- 1.0) > sum of CIBz (2.42 +/- 0.18), although these rankings varied considerably over the summer. The alpha- and gamma-HCH and lower chlorinated PCB congeners were the most common POPs in C. hyperboreus. The relationship between bioconcentration factor (BCF) and octanol-water partition coefficient (Kow) observed for the C. hyperboreus was linear and near 1:1 (slope = 0.72) for POPs with a log Kow between 3 and 6 but curvilinear when hydrophobic POPs (log Kow > 6) were included. Concentrations of sum of HCH. Sum of CHLOR and sum of CIBz increased over the sampling period, but no change in sum of PCB or sum of DDT was observed. After removing the effects of time, the variables lipid content, water content, delta15N and delta13C did not describe POP concentrations in C. hyperboreus. These results suggest that hydrophobic POP (log Kow = 3.86.0) concentrations in zooplankton are likely to reflect water concentrations and that POPs do not biomagnify in C. hyperboreus or likely in other small, herbivorous zooplankton.

Examination of the behavior and liver and thyroid histology of juvenile rainbow trout (Oncorhynchus mykiss) exposed to high dietary concentrations of C(10)-, C(11)-, C(12)- and C(14)-polychlorinated n-alkanes.

Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to high dietary concentrations of six polychlorinated n-alkane (PCAs) (C(10)H(15.5)C(6.5), C(10)H(15.3)Cl(6.7),C(11)H(18.4)Cl(5.6),C(12)H(19.5)Cl(6.5),C(14)H(24.9)Cl(5.1) and C(14)H(23.3)Cl(6.7)) for 21 to assess their effects on behavior and liver and thyroid histology and for 85 days to assess histology for a longer term exposure. This is the first histological work using PCAs of known carbon chain length and chlorine content and the first effort to examine the histopathology of fish exposed to PCAs. PCAs, also known as chlorinated paraffins, are complex industrial products for which there is a lack of toxicological data on individual congeners. With the exception of trout exposed to C(14)H(24.9)Cl(5.1), which had much lower exposure concentrations, many of the trout exposed to the PCAs (whole fish concentrations 0.22-5.5 microg g(-1)) showed a diminished or no startle response, loss of equilibrium, and developed a dark coloration. These responses are indicative of a narcotic toxicological mode-of-action. Histopathological lesions were observed in the livers of trout from each exposure group. However, the most severe histopathologies were observed in the livers of fish exposed to C(10)H(15.3)Cl(6.7) and C(11)H(18.4)Cl(5.6) (whole fish concentrations 0.92 and 5.5 microg g(-1), respectively), in which extensive fibrous lesions were present that were not observed in any other exposure group. Other alterations observed in all treatment groups included hepatocyte necrosis, sites of inflammation, and glycogen/lipid depletion. The relative sizes of hepatocytes of PCA exposed trout were smaller than control trout, although only a few of the observed differences were statistically significant. No lesions were present in the thyroid, although trout exposed to C(10)H(15.5)Cl(6.5) (whole fish concentration 0.84 microg g(-1)) had slightly more active thyroids, as indicated by an increased mean thyroid epithelium cell height relative to controls. It would appear that PCA toxicity is inversely related to carbon chain length, as has been observed in similar studies using mammals. The concentrations in the fish from this experiment were at levels that have been reported in invertebrates and fish from contaminated sites in the Great Lakes. However, the exposure concentrations were likely much greater in these experiments compared with the environment and require further study.

Hexachlorocyclohexane (HCH) isomers and chiral signatures of alpha-HCH in the Arctic marine food web of the Northwater Polynya.

Concentrations of hexachlorocyclohexane (HCH) isomers (alpha, beta, and gamma) and enantiomer fractions (EFs) of alpha-HCH were determined in the Northwater Polynya Arctic marine food web. Relative food web structure was established using trophic level models based on organic delta 15N values. Concentrations of HCH in the samples collected, including water, sediment, benthic invertebrates (four species), pelagic zooplankton (six species), Arctic cod, seabirds (seven species), and ringed seal, were in the range previously reported for the Canadian Arctic. The relative proportion of the HCH isomers varied across the food web and appeared to be related to the biotransformation capacity of each species. For invertebrates and fish the biomagnification factors (BMFs) of the three isomers were > 1 and the proportion of each isomer and the EFs of alpha-HCH were similar to water, suggesting minimal biotransformation. Seabirds appear to readily metabolize gamma- and alpha-HCH based on low BMFs for these isomers, high proportions of beta-HCH (62-96%), and high EFs (0.65-0.97) for alpha-HCH. The alpha- and beta-HCH isomers appear to be recalcitrant in ringed seals based on BMFs > 1 and near racemic EFs for alpha-HCH. The beta isomer appears to be recalcitrant in all species examined and had an overall food web magnification factor of 3.9. EFs of alpha-HCH and the proportion of beta-HCH in sigma-HCH in the food web were highly correlated (r2 = 0.92) suggesting that EFs were a good indicator of a species capability to biotransform alpha-HCH.

Chlordane components and metabolites in seven species of Arctic seabirds from the Northwater Polynya: relationships with stable isotopes of nitrogen and enantiomeric fractions of chiral components.

The Northwater Polynya (NOW) is a large area of year-round open water found in the high Arctic between Ellesmere Island and Greenland. NOW has high biological productivity compared with other arctic marine areas, and supports large populations of several seabird species. Seven species of seabirds, dovekie (Alle alle, DOVE), thick-billed murre (Uria lomvia, TBMU), black guillemot (Cepphus grylle, BLGU), black-legged kittiwake (Rissa tridactyla, BLKI), ivory gull (Pagophila eburnea, IVGU), glaucous gull (Larus hyperboreus, GLGU) and northern fulmar (Fulmaris glacialis, NOFU) were collected in May and June 1998 to determine chlordane concentrations in liver and fat and to examine species differences, relationships with stable isotopes of nitrogen, and enantiomeric fractions (EFs) of chiral components. sigma CHLOR concentrations varied over an order of magnitude among species, from a low of 176 +/- 19 ng/g (lipid corrected) in TMBU liver to a high of 3190 +/- 656 ng/g (lipid corrected) in NOFU liver. Lipid-corrected concentrations of chlordane did not vary between sex for any species or between fat and liver except for the DOVE, that had fat concentrations that were significantly greater than the liver. delta 15N values described a significant percentage of the variability of concentrations for most chlordane components, although less than what has been reported for whole food chains. Slopes of delta 15N versus concentration of chlordane components and sigma CHLOR were similar with the exception of those which were metabolized (trans-chlordane) or formed through biotransformation (oxychlordane). The relative proportions of chlordane components in seabirds were related to phylogeny; the procellariid (NOFU) had the greatest percentage of oxychlordane (> 70%), followed by the larids (BLKI, IVGU and GLGU; 40-50%) and the alcids (DOVE and BLGU; 10-20%). The exception was TBMU, an alcid, where oxychlordane made up > 40% of its chlordane. EFs of chiral components failed to predict concentration or trophic level, but did identify biotransformation differences between species and chlordane components. TBMU appeared to have a greater capacity to metabolize and eliminate chlordane, based on high proportions of oxychlordane, the highest EFs for oxychlordane and heptachlor epoxide, and a delta 15N-sigma CHLOR value which was well below the relationships developed for all seabird species.

Influence of chemical and biological factors on trophic transfer of persistent organic pollutants in the northwater polynya marine food web.

Persistent organic pollutants (POPs) and stable isotopes of nitrogen (delta 15N) were measured in zooplankton (6 species), a benthic invertebrate (Anonyx nugax), Arctic cod (Boreogadus saida), seabirds (6 species), and ringed seals (Phoca hispida) collected in 1998 in the Northwater Polynya to examine effects of biological and chemical factors on trophic transfer of POPs in an Arctic marine food web. Strong positive relationships were found between recalcitrant POP concentrations (lipid corrected) and trophic level based on stable isotopes of nitrogen, providing clear evidence of POP biomagnification in Arctic marine food webs. Food web magnification factors (FWMFs), derived from the slope of the POP--trophic level relationship, provided an overall magnification factor for the food web but over and underestimated biomagnification factors (BMFs) based on predator--prey concentrations in poikilotherms (fish) and homeotherms (seabirds and mammals), respectively. Greater biomagnification in homeotherms was attributed to their greater energy requirement and subsequent feeding rates. Within the homeotherms, seabirds had greater BMFs than ringed seals, consistent with greater energy demands in birds. Scavenging from marine mammal carcasses and accumulation in more contaminated winter habitats were considered important variables in seabird BMFs. Metabolic differences between species resulted in lower than expected BMFs, which would not be recognized in whole food web trophic level--POP relationships. The use of sigma POP groups, such as sigma PCB, is problematic because FWMFs and BMFs varied considerably between individual POPs. FWMFs of recalcitrant POPs had a strong positive relationship with log octanol--water partition coefficient (Kow). Results of this study show the utility of using delta 15N to characterize trophic level and trophic transfer of POPs but highlight the effects of species and chemical differences on trophic transfer of POPs that can be overlooked when a single magnification factor is applied to an entire food web.

Environmental chemistry and toxicology of polychlorinated n-alkanes.

Polychlorinated-n-alkanes (PCAs) or chlorinated paraffins consist of C10 to C30 n-alkanes with chlorine content from 30% to 70% by mass. PCAs are used as high-temperature lubricants, plasticizers, flame retardants, and additives in adhesives, paints, rubber, and sealants. This review presents the existing data on the environmental chemistry and toxicology of PCAs and a preliminary exposure and risk assessment. There is limited information on the levels, fate, or biological effects of PCAs in the environment. This results both from the difficulty associated with quantifying PCAs, because of the complexity inherent to commercial formulations, and from the limited knowledge of their physicochemical properties and biodegradation rates. There are indications that PCAs are widespread environmental contaminants at ng/L levels in surface waters and ng/g (wet wt) levels in biota. However, environmental measurements of PCAs are very limited in the U.S. and Canada, and are only slightly more detailed in western Europe. Assuming that reported water concentrations are mainly caused by the short chain (C10-C13) compounds, aquatic organisms may be at risk from exposure to PCAs. Fugacity level II modeling for two representative PCAs, using the best available physicochemical property data and estimated degradation rates, suggested that C16C24Cl10 would achieve higher concentrations in biota, sediment, and soil than C12H20Cl6 because of slower degradation rates and lower water solubility. Environmental residence time of C16H24Cl10 is estimated to be 520 d compared to 210 d for C12H20Cl6. Future studies will require better analytical methods and reference materials certified for PCA content. Additional data are needed to evaluate exposure of biota to PCAs in the environment, particularly in light of their continued production and usage around the globe.