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Perfluorooctane sulfonate (PFOS) is a persistent contaminant that has been found globally within the environment. Key data gaps exist in the toxicity of PFOS to marine organisms, especially estuarine species that are crucial to the food web: fish, shrimp, and mollusks. This study developed toxicity thresholds for larval estuarine species, including grass shrimp (Palaemon pugio), sheepshead minnows (Cyprinodon variegatus), mysids (Americamysis bahia), and Eastern mud snails (Tritia obsoleta). Multiple abiotic stressors (salinity and temperature) were included as variables in testing the toxicity of PFOS. Acute 96 h toxicity testing under standard test conditions of 25 °C and 20 ppt seawater yielded LC50 values of 0.919 mg/L for C. variegatus, 1.375 mg/L for A. bahia, 1.559 mg/L for T. obsoleta, and 2.011 mg/L for P. pugio. The effects of increased temperature (32 °C) and decreased salinity (10 ppt) varied with test species. PFOS toxicity for the sheepshead minnows increased with temperature but was not altered by decreased salinity. For grass shrimp and mud snails, PFOS toxicity was greater under lower salinity. The combination of higher temperature and lower salinity was observed to lower the toxicity thresholds for all species. These data demonstrate that expanding toxicity testing to include a wider range of parameters will improve the environmental risk assessment of chemical contaminants, especially for species inhabiting dynamic estuarine ecosystems. [ABSTRACT FROM AUTHOR]

Chemical dispersants can be a beneficial method for breaking up oil slicks; however, their use in mitigation could pose potential toxic effects on the marine ecosystem. Dispersants may be transported to lower salinity habitats, where toxicity data for aquatic species have not been established. This study examined the effect of salinity on oil dispersant toxicity in the eastern mud snail, Ilyanassa obsoleta, using two dispersants authorized for oil spill response, Corexit® 9500A and Finasol® OSR 52. Median lethal toxicity values (LC50) and sublethal effects were examined at 10, 20, and 30 ppt salinity in adult and larval mud snails. Two biomarkers (lipid peroxidation and acetylcholinesterase) were used to measure sublethal effects. The 96-h static renewal LC50 values indicated significant differences in toxicity between dispersants and salinities. Larval snails were significantly more sensitive than adult snails to both dispersants, and both life stages were significantly more sensitive to Finasol than to Corexit. Larval snails were more sensitive to dispersants at lower salinity, but adult snails were more sensitive at higher salinities. Dispersants increased lipid peroxidation and decreased acetylcholinesterase activity. These results demonstrate that dispersant toxicity varies among compounds and organism life stages, and that physicochemical properties of the environment, such as salinity, can affect the potential toxicity to estuarine species. [ABSTRACT FROM AUTHOR]

Global climate change effects will vary geographically, and effects on estuaries should be independently considered. This review of the impacts of climate change on the ecotoxicology of chemical contaminants aims to summarize responses that are specific to estuarine species. Estuarine organisms are uniquely adapted to large fluctuations in temperature, salinity, oxygen, and pH, and yet future changes in climate may make them more susceptible to chemical contaminants. Recent research has highlighted the interactive effects of chemical and nonchemical stressors on chemical uptake, metabolism, and organism survival. Assessments have revealed that the nature of the interaction between climate variables and chemical pollution will depend on estuarine species and life stage, duration and timing of exposure, prior stressor exposure, and contaminant class. A need for further research to elucidate mechanisms of toxicity under different abiotic conditions and to incorporate climate change factors into toxicity testing was identified. These efforts will improve environmental risk assessment of chemical contaminants and management capabilities under changing climate conditions. [ABSTRACT FROM AUTHOR]

Pyrethroid insecticides are widely used on agricultural crops, as well as for nurseries, golf courses, urban structural and landscaping sites, residential home and garden pest control, and mosquito abatement. Evaluation of sensitive marine and estuarine species is essential for the development of toxicity testing and risk-assessment protocols. Two estuarine crustacean species, Americamysis bahia (mysids) and Palaemonetes pugio (grass shrimp), were tested with the commonly used pyrethroid compounds, lambda-cyhalothrin, permethrin, cypermethrin, deltamethrin, and phenothrin. Sensitivities of adult and larval grass shrimp and 7-day-old mysids were compared using standard 96-h LC50 bioassay protocols. Adult and larval grass shrimp were more sensitive than the mysids to all the pyrethroids tested. Larval grass shrimp were approximately 18-fold more sensitive to lambda-cyhalothrin than the mysids. Larval grass shrimp were similar in sensitivity to adult grass shrimp for cypermethrin, deltamethrin, and phenothrin, but larvae were approximately twice as sensitive to lambda-cyhalothrin and permethrin as adult shrimp. Acute toxicity to estuarine crustaceans occurred at low nanogram per liter concentrations of some pyrethroids, illustrating the need for careful regulation of the use of pyrethroid compounds in the coastal zone. © 2013 Wiley Periodicals, Inc. Environ Toxicol 29: 1099-1106, 2014. [ABSTRACT FROM AUTHOR]

Pharmaceuticals and personal care products (PPCPs) such as caffeine and sulfamethoxazole have been detected in the estuarine environment. The present study characterized effects of a maternal exposure of these compounds on the development of the daggerblade grass shrimp Palaemonetes pugio from embryo to juvenile life stage. Ovigerous females were exposed to either caffeine (20 mg/L), sulfamethoxazole (60 mg/L), or a mixture of both (20 mg/L caffeine and 60 mg/L sulfamethoxazole). Embryos were then removed from the females and the effects of the PPCPs on hatching, metamorphosis, juvenile growth, and overall mortality were determined. No significant effect was observed on gravid female survival after 5 d of exposure to caffeine, sulfamethoxazole, or the mixture; however, development of the embryos on the female shrimp was delayed in the mixture. Caffeine and sulfamethoxazole in the mixture significantly reduced embryo survival. There was a significant effect of caffeine, sulfamethoxazole, and the mixture on embryo hatching time. Exposure to sulfamethoxazole alone significantly delayed larval metamorphosis. Exposure to caffeine and sulfamethoxazole separately led to significantly smaller length of juvenile shrimp. Maternal exposure to caffeine and sulfamethoxazole, individually and in mixture, resulted in negative effects on P. pugio offspring survival and development; however, the concentrations tested in the present study were well above maximum detected field concentrations. These results may be incorporated into PPCP risk assessments to protect sensitive estuarine ecosystems more effectively. Environ Toxicol Chem 2014; 33:2120-2125. © 2014 SETAC [ABSTRACT FROM AUTHOR]

Ecological risk assessments are, in part, based on results of toxicity tests conducted under standard exposure conditions. Global climate change will have a wide range of effects on estuarine habitats, including potentially increasing water temperature and salinity, which may alter the risk assessment of estuarine pollutants. We examined the effects of increasing temperature and salinity on the toxicity of common herbicides (irgarol, diuron, atrazine, and ametryn) to the phytoplankton species Dunaliella tertiolecta. Static 96-h algal bioassays were conducted for each herbicide under four exposure scenarios: standard temperature and salinity (25°C, 20 ppt), standard temperature and elevated salinity (25°C, 40 ppt), elevated temperature and standard salinity (35°C, 20 ppt), and elevated temperature and elevated salinity (35°C, 40 ppt). The endpoints assessed were algal cell density at 96 h, growth rate, chlorophyll a content, lipid content, and starch content. Increasing exposure temperature reduced growth rate and 96-h cell density but increased the cellular chlorophyll and lipid concentrations of the control algae. Exposure condition did not alter starch content of control algae. Herbicides were found to decrease growth rate, 96 h cell density, and cellular chlorophyll and lipid concentrations, while starch concentrations increased with herbicide exposure. Herbicide effects under standard test conditions were then compared with those observed under elevated temperature and salinity. Herbicide effects on growth rate, cell density, and starch content were more pronounced under elevated salinity and temperature conditions. To encompass the natural variability in estuarine temperature and salinity, and to account for future changes in climate, toxicity tests should be conducted under a wider range of environmental conditions. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2013. [ABSTRACT FROM AUTHOR]

Microalgal species vary in their sensitivity to the triazine herbicide, atrazine. This study examined both atrazine uptake and cellular characteristics of microalgae to determine if either can be used to predict algal sensitivity. Standard toxicity tests were performed on five microalgal species, each representing a different algal division or habitat. Test species listed in order of increasing sensitivity were: Isochrysis galbana, Dunaliella tertiolecta, Phaeodactylum tricornutum, Pseudokirchneriella subcapitata, and Synechococcus sp. Each species was exposed to 14C-atrazine at its growth rate EC50 concentration (44–91 μg/L). At five time-points over 96 h, samples were filtered to collect algae and washed with unlabeled atrazine to displace labeled atrazine loosely absorbed to the cell surface. Radioactivity present on filters and in the growth medium was measured by liquid scintillation counting. Relationships between algal species-sensitivity to atrazine and compound uptake, cell dry weight, cell volume, and cell surface area were determined by linear regression analysis. Cell size measurements (based on dry weight, biovolume, and surface area) were significantly correlated with atrazine uptake (R2>0.45, P-value < 0.05). There was a significant correlation between atrazine uptake and species-sensitivity to atrazine (R2=0.5413, P-value = 0.0012). These results indicate that smaller cells with greater surface area to volume ratios will incorporate more atrazine, and in general, will be more sensitive to atrazine exposure. However, I. galbana, with small cell size and relatively high atrazine uptake was the least sensitive species tested. This species and others may have mechanisms to compensate for atrazine stress that make predicting responses of microalgal communities difficult. [Copyright &y& Elsevier]

This study represents the first in a series of validation experiments for the modular estuarine mesocosm testing direct pesticide effects. Endosulfan, an agricultural insecticide, was selected as a model contaminant for studying direct toxic effects as well as uptake of this model contaminant by estuarine biota. The grass shrimp, Palaemonetes pugio, and the mummichog, Fundulus heteroclitus, showed significant mortality (96 h LC50: 0.12 and 2.2 μg/l, respectively) to endosulfan as predicted by laboratory bioassays. There was no effect on fiddler crabs and eastern oysters. The mesocosm was also useful in demonstrating the bioconcentration of endosulfan by eastern oysters (bioconcentration factor [BCF]=375) similar to results reported in field studies. This study illustrates the modular estuarine mesocosms'' ability to detect direct effects of pesticide exposure and the uptake of a pesticide by estuarine fauna. [Copyright &y& Elsevier]

Microorganisms contribute significantly to primary production, nutrient cycling, and decomposition in estuarine ecosystems; therefore, detrimental effects of pesticides on microbial species may have subsequent impacts on higher trophic levels. Pesticides may affect estuarinemicroorganisms via spills, runoff, and drift. Both the structure andthe function of microbial communities may be impaired by pesticide toxicity. Pesticides may also be metabolized or bioaccumulated by microorganisms. Mechanisms of toxicity vary, depending on the type of pesticide and the microbial species exposed. Herbicides are generally most toxic to phototrophic microorganisms, exhibiting toxicity by disrupting photosynthesis. Atrazine is the most widely used and most extensively studied herbicide. Toxic effects of organophosphate and organochlorine insecticides on microbial species have also been demonstrated, although their mechanisms of toxicity in such nontarget species remain unclear. There is a great deal of variability in the toxicity ofeven a single pesticide among microbial species. When attempting to predict the toxicity of pesticides in estuarine ecosystems, effects of pesticide mixtures and interactions with nutrients should be considered. The toxicity of pesticides to aquatic microorganisms, especially bacteria and protozoa, is an area of research requiring further study. [ABSTRACT FROM AUTHOR]