Effects of mercury (Hg) on birds have been studied extensively and with increasing frequency in recent years. The authors conducted a comprehensive review of methylmercury (MeHg) effects on bird reproduction, evaluating laboratory and field studies in which observed effects could be attributed primarily to Hg. The review focuses on exposures via diet and maternal transfer in which observed effects (or lack thereof) were reported relative to Hg concentrations in diet, eggs, or adult blood. Applicable data were identified for 23 species. From this data set, the authors identified ranges of toxicity reference values suitable for risk-assessment applications. Typical ranges of Hg effect thresholds are approximately 0.2 mg/kg to >1.4 mg/kg in diet, 0.05 mg/kg/d to 0.5 mg/kg/d on a dose basis, 0.6 mg/kg to 2.7 mg/kg in eggs, and 2.1 mg/kg to >6.7 mg/kg in parental blood (all concentrations on a wet wt basis). For Hg in avian blood, the review represents the first broad compilation of relevant toxicity data. For dietary exposures, the current data support TRVs that are greater than older, commonly used TRVs. The older diet-based TRVs incorporate conservative assumptions and uncertainty factors that are no longer justified, although they generally were appropriate when originally derived, because of past data limitations. The egg-based TRVs identified from the review are more similar to other previously derived TRVs but have been updated to incorporate new information from recent studies. While important research needs remain, a key recommendation is that species not yet tested for MeHg toxicity should be evaluated using toxicity data from tested species with similar body weights. Environ Toxicol Chem 2017;36:294-319. # 2016 SETAC

Contaminant bioavailability via digestive exposure was examined for 18 species of marine benthic invertebrates, using incubation of digestive fluids with sediments that were spiked with either radiolabeled benzo-[a]-pyrene (BaP) or zinc. Interphyletic trends in contaminant solubilization were compared with measures of digestive biochemistry, including enzyme activities, surfactancy, pH, and fluid phase organic carbon, amino acids, and lipids. Contaminant solubilization ranged from values equal to that of a seawater control to as much as an order of magnitude higher but were lower than those obtained with commonly used chemical extractants. Digestive fluids from echinoderms and a cnidarian tended to be relatively weak, those from polychaetes and echiurans were relatively strong, and those from taxa such as sipunculans and mollusks were intermediate. These trends correlated strongly with concentrations or activities of digestive biochemicals but not with pH. These correlations are consistent with previous work on mechanisms of digestive solubilization of polycyclic aromatic hydrocarbons (PAH) and metals, though strong covariance among digestive parameters does not allow this approach to be used for identification of specific mechanism(s).

No abstract

We present a survey of feeding behavior of benthic organisms in oscillatory flow and sediment fluxes. These results are based on seventeen species from five phyla and several feeding guilds from an intertidal sandflat and the continental shelf of the Mid-Atlantic coast, U.S.A. General responses to oscillatory flows are: (1) nearly immediate change in feeding behavior or position of feeding appendage when flow is initiated, (2) decrease in feeding area for surface deposit feeders, often (3) alteration of feeding mode, and when anatomically permitted (4) rotation of feeding appendages to track flow direction. At high sediment fluxes, responses are functional group and morphology-specific. Organisms with one or two muscular feeding appendages continue to feed (e.g., Spio setosa, Spiochaetopterus oculatus and Emerita talpoida), while those with a crown of tentacles cannot (e.g., Pista palmata, Serpula vermicularis granulosa, and Terebella rubra). A continental shelf brittle star, Amphipholis squamata, ceases suspension feeding in high flows. Organisms with strong tentacles feed at the sediment surface in much restricted feeding area (Marenzelleria jonesi and Saccoglossus kowalevskii). Organisms with long, thin palps coil them helically and capture particles in near-bed flux (Spiochaetopterus oculatus and Spio setosa). Siphonate feeders maintain siphon tips near the sediment surface and continue pumping (Ensis directus, Mercenaria mercenaria and Tagelus plebeius). A sedentary omnivore (Diopatra cuprea) is able to capture food particles in low and moderate flow, but in high flows the tube opening is closed. Motile scavengers may either increase (Pagurus longicarpus) or decrease (Echinarachnius parma and Ilyanassa obsoleta) movement rate. Of all species studied, only the burrowing predatory starfish Astropecten americanus showed no change in behavior with respect to oscillatory flow.In addition, we report detailed quantitative changes in feeding behavior by a facultative suspension-feeding spionid polychaete Spio setosa and an obligate deposit-feeding terebellid polychaete Terebella rubra which indicate hysteresis or time-dependence in the response to flow and sediment flux. We attempt a summary of responses by functional group and morphology and suggest that new descriptive terms combining low-flow feeding behavior and morphology are needed to characterize feeding modes adequately. Our analysis suggests that it is important to consider the possible presence of flow and flux micro-environments, an individual organisms's variability, flow history and the various time scales of behavioral responses and other biological rate processes. There is a current need for dynamic feeding models that incorporate these factors as well as for experimental tests of the derived predictions.]. Graduate Collegeof Marine Studies,Universityof Delaware,Lewes,Delaware, ]9958-]298,U.S.A. 2. Present address:

No abstract

Traffic- and urban-influenced areas are prone to enhanced pollution with products of incomplete combustion of fossil fuels and biomass such as black carbon or polycyclic aromatic hydrocarbons (PAHs). Black carbon is composed of aromatic and graphitic structures and may act as a carrier for pollutants such as PAHs and heavy metals. However, little is known about possible contributions of traffic-derived black carbon to the black carbon inventory in soils. Similar uncertainties exist regarding the contribution of different pollutant sources to total PAH and black carbon contents. Therefore, the objective of this study was to quantify the importance of traffic pollution to black carbon and PAH inventories in soils. PAH contamination of soils adjacent to a major German highway in the urban area of Bayreuth with about 50,000 vehicles per day was in the same order of magnitude compared to highway-close soils reported in other studies. Using molecular (black carbon and PAHs) and compound-specific stable carbon isotope evidence (PAHs) it was demonstrated that this contamination originated not only from automobile exhausts, here primarily diesel, but also from tire abrasion and tailpipe soot which significantly contributed to the traffic-caused black carbon and PAH contamination. Low molecular weight PAHs were more widely transported than their heavy molecular counterparts (local distillation), whereas highway-traffic-caused black carbon contamination was distributed to at least 30 m from the highway. On the other hand, urban fire exhausts were distributed more homogeneously among the urban area.

Contaminant bioavailability via digestive exposure was examined for 18 species of marine benthic invertebrates, using incubation of digestive fluids with sediments that were spiked with either radiolabeled benzo-[a]-pyrene (BaP) or zinc. Interphyletic trends in contaminant solubilization were compared with measures of digestive biochemistry, including enzyme activities, surfactancy, pH, and fluid phase organic carbon, amino acids, and lipids. Contaminant solubilization ranged from values equal to that of a seawater control to as much as an order of magnitude higher but were lower than those obtained with commonly used chemical extractants. Digestive fluids from echinoderms and a cnidarian tended to be relatively weak, those from polychaetes and echiurans were relatively strong, and those from taxa such as sipunculans and mollusks were intermediate. These trends correlated strongly with concentrations or activities of digestive biochemicals but not with pH. These correlations are consistent with previous work on mechanisms of digestive solubilization of polycyclic aromatic hydrocarbons (PAH) and metals, though strong covariance among digestive parameters does not allow this approach to be used for identification of specific mechanism(s).

Triclosan, an antimicrobial compound used in personal care products, occurs in the aquatic environment due to residual concentrations in municipal wastewater treatment effluent. We evaluate triclosan-related risks to the aquatic environment, for aquatic and sediment-dwelling organisms and for aquatic-feeding wildlife, based on measured and modeled exposure concentrations. Triclosan concentrations in surface water, sediment, and biota tissue are predicted using a fugacity model parameterized to run probabilistically, to supplement the limited available measurements of triclosan in sediment and tissue. Aquatic toxicity is evaluated based on a species sensitivity distribution, which is extrapolated to sediment and tissues assuming equilibrium partitioning. A probabilistic wildlife exposure model is also used, and estimated doses are compared with wildlife toxicity benchmarks identified from a review of published and proprietary studies. The 95th percentiles of measured and modeled triclosan concentrations in surface water, sediment, and biota tissues are consistently below the 5th percentile of the respective species sensitivity distributions, indicating that, under most scenarios, adverse affects due to triclosan are unlikely.