Search

To track the long term bioaccumulation of 137 Cs in marine organisms off the Pacific Northwest coast of Canada, we developed a time dependent bioaccumulation model for 137 Cs in a marine mammalian food web that included fish-eating resident killer whales. The model outcomes show that 137 Cs can be expected to gradually bioaccumulate in the food web over time as demonstrated by the increase of the apparent trophic magnification factor of 137 Cs, ranging from 0.76 after 1 month of exposure to 2.0 following 30 years of exposure. 137 Cs bioaccumulation is driven by relatively rapid dietary uptake rates, moderate depuration rates in lower trophic level organisms and slow elimination rates in high trophic level organisms. Model estimates of the 137 Cs activity in species of the food web, based on current measurements and forecasts of 137 Cs activities in oceanic waters and sediments off the Canadian Pacific Northwest, indicate that the long term 137 Cs activities in fish species including Pacific herring, wild Pacific salmon, sablefish and halibut will remain well below the current 137 Cs-Canada Action Level for consumption (1000 Bq/kg) following a nuclear emergency. Killer whales and Pacific salmon are expected to exhibit the largest long term 137 Cs activities and may be good sentinels for monitoring 137 Cs in the region. Assessment of the long term consequences of 137 Cs releases from the Fukushima aftermath should consider the extent of ecological magnification in addition to ocean dilution. [ABSTRACT FROM AUTHOR]

Abstract: Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in blubber biopsy samples from 22 live-captured Steller sea lions (Eumetopias jubatus) that had just entered the Strait of Georgia, British Columbia, Canada, for their overwintering feeding season. ∑PBDE ranged from 50μgkg−1 (lipid weight) in adult females to 3780μgkg−1 in subadult individuals. ∑PCBs ranged from 272μgkg−1 in adult females to 14280μgkg−1 in subadult individuals. While most PBDE and PCB congeners were transferred through milk to pups, PCBs with log K OW >7.0 (PCBs 206, 207, 208 and 209) appeared constrained, resulting in a lighter mixture in pups compared to adult females. The ratio of individual PCB congeners by metabolic group (Groups I, II, III, IV and V) to PCB-153 regressed against length of males suggested poor biotransformation of these compounds (slopes did not differ from zero, p >0.05). PBDE congeners 49, 99, 153 and 183 appeared bioaccumulative (slopes of ratio BDE/PCB 153 versus length were higher than zero, p <0.05), but the dominance of the single congener, BDE-47 (64% of total PBDEs), likely due in part to debromination pathways, reduced our ability to explore congener-specific dynamics of PBDEs in these pinnipeds. With 80% of our Steller sea lions exceeding a recent toxicity reference value for PCBs, the fasting-associated mobilization of these contaminants raises concerns about a heightened vulnerability to adverse effects during annual migrations. [Copyright &y& Elsevier]

Abstract: Data are scarce describing the concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides in sea turtle eggs. The purpose of this study was to establish appropriate sample collection methodology to monitor these contaminants in sea turtle eggs. Contaminant concentrations were measured in yolk samples from eggs that failed to hatch from three loggerhead sea turtle (Caretta caretta) nests collected in southern Florida to determine if concentrations change through embryonic development. One to three egg yolk samples per nest were analyzed from early, middle, and late developmental stages (n =22 eggs total). PCB and pesticide concentrations were determined by gas chromatography with electron capture detection (GC–ECD). Geometric mean concentrations of ∑PCBs (52 congeners), ∑DDTs, ∑chlordanes, and dieldrin in all eggs were 65.0 (range=7.11 to 3930 ng/g lipid), 67.1 (range=7.88 to 1340 ng/g lipid), 37.0 (range=4.04 to 685 ng/g lipid), and 11.1 ng/g lipid (range=1.69 to 44.0 ng/g lipid), respectively. Early and middle developmental stage samples had similar concentrations of PCBs and organochlorine pesticides on a wet-mass basis (ng/g tissue extracted), but the concentrations doubled by the late stage. This increase is most likely attributable to the 50% increase in lipid content observed in the late-stage yolk. These findings indicate that an early-stage sample cannot be directly compared to a late-stage sample, especially from different nests. These preliminary findings also allowed us to calculate the minimum number of eggs per nest required for analysis to obtain an acceptable mean concentration per nest. More research is required to investigate geographical trends of contaminant concentrations and potential health effects (i.e., abnormalities) caused by these contaminants on sea turtle development. [Copyright &y& Elsevier]

A comprehensive investigation of PAHs' occurrence and distribution in the water, sediment, and fish samples of Musa estuary was conducted. Concentrations of 16 PAHs in water, sediment and two commercial fish ranged from 0.14 to 0.66 ng/l, 67.21 to 82.92 ng/g dw, 50.25 to 99.39 ng/g fdw in J. belangerii , and 40.14 to 76.93 ng/g fdw in B. orentalis , respectively. High molecular weight PAHs (HMW-PAHs) were generally predominant compared to low molecular weight PAHs (LMW-PAHs). Additionally, the study of the PAHs fingerprints, using specific ratios, suggests the predominance of a pyrolytic origin for observed PAHs. 4-ring PAHs were observed more in the two species, whereas the PAHs in sediments were dominated by three and five ring compounds. The Incremental lifetime Cancer Risk (ILCR) for fish was ≤10 E 10−5, showed a minimal possible risk of cancer for children and adult. • Polycyclic Aromatic Hydrocarbons (PAHs) have been determined in tissues of fish, water, and sediments, from the Musa estuary and Persian Gulf. • The study of the PAHs fingerprints suggested that PAHs were primarily derived from different sources mainly petroleum and combustion sources. • Findings provide baseline data for further research on ecotoxicity of PAHs in biota and abiota. • The occurrence of PAHs in seafood for human consumption is cause for concern. [ABSTRACT FROM AUTHOR]

Abstract: The feeding behavior of marine predators varies with the level of competition to which they are exposed. Populations living in the same or overlapping geographic regions (sympatric) are generally subject to inter-specific competition, which can lead to the development of differing trophic strategies that maximize both nutritional and reproductive efficiency. The otariids of the islands in the western Galapagos Archipelago represent appropriate subjects for studying the response mechanisms of sympatric species exposed to strong competition, both trophic and spatial. The present study has focused on evaluating the possible differences in the trophic niches of the Galapagos sea lion (Zalophus wollebaeki) and the Galapagos fur seal (Arctocephalus galapagoensis) over time, based upon the analysis of stable isotope ratios of carbon and nitrogen (δ13C and δ15N), and observation of both species at sea. A comparative analysis of the isotopic signal of skin samples from pups of both species was performed for rookeries on Fernandina Island between 2003 and 2009. Analyses of the isotopic signal present in prey covering the entire trophic range of these predators were also performed, in order to relate this information to otariid sighting records collected during offshore cruises in 1993–1994 and 2000. The δ13C and δ15N values defined differences in the feeding zones and in the trophic level of each species; which were related with the interannual variability of the ecosystem, i.e. El Niño and La Niña events. Whereas Z. wollebaeki showed a coastal (inshore) foraging strategy, relying on the consumption of small epipelagic fishes, A. galapagoensis turned out to be a more oceanic (offshore) predator, with a preference for small squid. These results are in good agreement with the distribution of these animals at sea, as indicated by the sighting data. The findings of this study provide new insights to our understanding of how sympatric species exposed to strong inter-specific competition can develop foraging strategies leading to a decreasing level of food competition and facilitate their survival in a stochastic environment that is highly demanding in terms of the availability of resources. [Copyright &y& Elsevier]