Contaminant concentrations and risks associated with the Pacific oyster in the highly urbanized San Diego Bay.

Contaminant concentrations in filter-feeding shellfish may indicate the health of coastal waters and consumption risks. Widespread expansion of the Pacific oyster (Crassostrea gigas) and its popularity as food make it a useful sentinel. We surveyed intertidal Pacific oysters in San Diego Bay, California for contaminants during summer 2018 and winter 2019. We compared contaminants in Pacific oyster to California mussel from California's State Mussel Watch Program (1993-2003) and human consumption thresholds. Contaminants such as neonicotinoid and chlorinated pesticides, selenium, and several metals were higher in Pacific oysters in summer, while PBDEs, benzylbutyl phthalate, and plastics were higher in winter. Contaminant levels were generally lower in Pacific oyster than mussel except for copper and zinc. Bay-wide PCB concentrations in oysters exceeded thresholds but individual samples (locations) also met or surpassed chlordane, PCB and PAH thresholds. Monitoring and risk assessments that consider species' biology, season, location, effects of multiple contaminants, and human consumption patterns will contribute to more effective consumption guidelines.

Persistent organic pollutants in green sea turtles (Chelonia mydas) inhabiting two urbanized Southern California habitats.

Within Southern California, east Pacific green sea turtles (Chelonia mydas) forage year-round, taking advantage of diverse food resources, including seagrass, marine algae, and invertebrates. Assessing persistent organic pollutants (POP) in green turtle aggregations in the Seal Beach National Wildlife Refuge (SBNWR, n = 17) and San Diego Bay (SDB, n = 25) can help quantify contamination risks for these populations. Blood plasma was analyzed for polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). PCBs and body size explained much of the separation of turtles by foraging aggregation in a principal component analysis. Turtles from SDB had significantly (p < 0.001) higher total PCBs than SBNWR turtles. Most PCBs detected in turtles were non-dioxin-like PCB congeners (153, 138, 99) that are associated with neurotoxicity. Recaptured turtles' POP levels changed significantly over time indicating significant variation in POP levels through time and space, even among adjacent foraging locations.

Trace metals in green sea turtles (Chelonia mydas) inhabiting two southern California coastal estuaries.

Foraging aggregations of east Pacific green sea turtles (Chelonia mydas) inhabit the Seal Beach National Wildlife Refuge (SBNWR) and San Diego Bay (SDB), two habitats in southern California, USA, located near urbanized areas. Both juvenile and adult green turtles forage in these areas and exhibit high site fidelity, which potentially exposes green turtles to anthropogenic contaminants. We assessed 21 trace metals (TM) bioaccumulated in green turtle scute and red blood cell (RBC) samples collected from SBNWR (n = 16 turtles) and SDB (n = 20 turtles) using acid digestion and inductively coupled plasma mass spectrometry. Principal component analyses of TM composition indicate that SBNWR and SDB turtles have location-specific contaminant signatures, characterized by differences in cadmium and selenium concentrations: SBNWR turtles had significantly more cadmium and selenium in RBC and more selenium in scute samples, than SDB turtles. Cadmium and selenium concentrations in RBC had a strong positive relationship, regardless of location. SBNWR turtles had higher selenium in RBCs than previously measured in other green turtle populations globally. Due to different retention times in blood vs. scute, these results suggest that SBNWR turtles have high long- and short-term selenium exposure. Turtles from SBNWR and SDB had higher trace metal concentrations than documented in green turtle populations that inhabit non-urbanized areas, supporting the hypothesis that coastal cities can increase trace metal exposure to local green turtles. Our study finds evidence that green turtle TM concentrations can differ between urbanized habitats and that long-term monitoring of these green turtles may be necessary.

Application of sediment toxicity identification evaluation techniques to a site with multiple contaminants.

Sediment toxicity identification evaluations (TIEs) are conducted to determine causes of adverse effects observed in whole-sediment toxicity tests. However, in multiple contaminant scenarios, it is problematic to partition contributions of individual contaminants to overall toxicity. Using data from a site with multiple inputs and contaminants of concern, the authors describe a quantitative approach for the TIE process by tracking toxicity units to determine whether all toxicity is accounted for. The initial step established the level of toxicity associated with the whole sediment and then partitioned sources of toxicity into general contaminant classes (e.g., ammonia, metals, nonpolar organic compounds). In this case, toxicity was largely the result of nonpolar organics, so the sediments were extracted and the extracts added back into dilution water and tested to confirm recovery of toxicity. Individual fractions were then generated using a solvent gradient and tested for toxicity. Fractions of interest were evaluated with gas chromatography/mass spectrometry to identify specific constituents associated with toxicity. Toxicity units associated with these constituents were then evaluated to determine probable associations with cause and whether all toxicity was accounted for. The data indicated that toxicity was associated with 2 contaminant classes, representing legacy compounds and contaminants of emerging concern, with the contribution of each varying across the site. Environ Toxicol Chem 2016;35:2456-2465. © 2016 SETAC.