This study examines ASTM Standard E1191-90, ``Standard Guide for Conducting Life-cycle Toxicity T... more This study examines ASTM Standard E1191-90, ``Standard Guide for Conducting Life-cycle Toxicity Tests with Saltwater Mysids,`` 1990, using Mysidopsis bahia, by comparing several test designs to assess growth, reproduction, and survival. The primary objective was to determine the most labor efficient and statistically powerful test design for the measurement of statistically detectable effects on biologically sensitive endpoints. Five different test designs were evaluated varying compartment size, number of organisms per compartment and sex ratio. Results showed that while paired organisms in the ASTM design had the highest rate of reproduction among designs tested, no individual design had greater statistical power to detect differences in reproductive effects. Reproduction was not statistically different between organisms paired in the ASTM design and those with randomized sex ratios using larger test compartments. These treatments had numerically higher reproductive success and lower within tank replicate variance than treatments using smaller compartments where organisms were randomized, or had a specific sex ratio. In this study, survival and growth were not statistically different among designs tested. Within tank replicate variability can be reduced by using many exposure compartments with pairs, or few compartments with many organisms in each. While this improves variance within replicate chambers, it doesmore » not strengthen the power of detection among treatments in the test. An increase in the number of true replicates (exposure chambers) to eight will have the effect of reducing the percent detectable difference by a factor of two.« less
Environmental Toxicology and Chemistry, Dec 1, 1998
Many environmental contaminants of concern produce aryl hydrocarbon (Ah) receptor‐mediated effect... more Many environmental contaminants of concern produce aryl hydrocarbon (Ah) receptor‐mediated effects often assessed as ethoxyresorufin‐O‐deethylase (EROD) activity. We modified a standardized embryonic and larval fish bioassay using an estuarine fish species (Fundulus heteroclitus) to include measurement of fluorescence in the urinary bladders of living embryos as a nondestructive indicator of EROD activity. This fluorescence was observed only in embryos exposed to the EROD substrate and Ah receptor agonists and was consistent in fluorescence characteristics with the EROD product, resorufin. Aryl hydrocarbon receptor‐agonist exposures at sublethal concentrations in the parts per billion range, produced significant increases in EROD fluorescence in embryos as young as 3 d postfertilization. These findings are consistent with the conclusion that this fluorescence method is a specific and sensitive nondestructive indicator of Ah receptor‐mediated effects in an embryonic fish. As such, this simple method may be useful for assessing effects of environmental contaminants on the early development of fishes and to link molecular indicators with organism‐level responses.
Ultraviolet light can activate certain polycyclic aromatic hydrocarbons (PAHs), inducing the prod... more Ultraviolet light can activate certain polycyclic aromatic hydrocarbons (PAHs), inducing the production of free radicals. In biological organisms these free radicals destroy tissues, causing up to a 4,000 fold increase in toxicity. This dramatic response is a potential marker for PAH contamination in environmental samples. Ultraviolet enhancement of toxicity has ecological relevance as well. An oil spill can release large amounts of PAHs into the marine environment. Oil spill assessments to date have not included observations of any phototoxic effect on pelagic larvae or juveniles of benthic or epibenthic invertebrates. In this study, larvae and juveniles of the bivalve, Mulinia lateralis and juveniles of the mysid shrimp, Mysidopsis bahia were exposed to individual PAHs, as well as the water accommodated fractions of several petroleum products to verify the ability of this method to detect PAHs in environmental samples, and to determine if phototoxicity is a concern during and afte...
The common loon, Gavia immer , is considered an emblematic and ecologically important example of ... more The common loon, Gavia immer , is considered an emblematic and ecologically important example of aquatic-dependent wildlife in North America. The northern breeding range of loons has contracted over the last century, presumably as a result of habitat degradation from human ...
This study examines ASTM Standard E1191-90, ``Standard Guide for Conducting Life-cycle Toxicity T... more This study examines ASTM Standard E1191-90, ``Standard Guide for Conducting Life-cycle Toxicity Tests with Saltwater Mysids,`` 1990, using Mysidopsis bahia, by comparing several test designs to assess growth, reproduction, and survival. The primary objective was to determine the most labor efficient and statistically powerful test design for the measurement of statistically detectable effects on biologically sensitive endpoints. Five different test designs were evaluated varying compartment size, number of organisms per compartment and sex ratio. Results showed that while paired organisms in the ASTM design had the highest rate of reproduction among designs tested, no individual design had greater statistical power to detect differences in reproductive effects. Reproduction was not statistically different between organisms paired in the ASTM design and those with randomized sex ratios using larger test compartments. These treatments had numerically higher reproductive success and lower within tank replicate variance than treatments using smaller compartments where organisms were randomized, or had a specific sex ratio. In this study, survival and growth were not statistically different among designs tested. Within tank replicate variability can be reduced by using many exposure compartments with pairs, or few compartments with many organisms in each. While this improves variance within replicate chambers, it doesmore » not strengthen the power of detection among treatments in the test. An increase in the number of true replicates (exposure chambers) to eight will have the effect of reducing the percent detectable difference by a factor of two.« less
Environmental Toxicology and Chemistry, Dec 1, 1998
Many environmental contaminants of concern produce aryl hydrocarbon (Ah) receptor‐mediated effect... more Many environmental contaminants of concern produce aryl hydrocarbon (Ah) receptor‐mediated effects often assessed as ethoxyresorufin‐O‐deethylase (EROD) activity. We modified a standardized embryonic and larval fish bioassay using an estuarine fish species (Fundulus heteroclitus) to include measurement of fluorescence in the urinary bladders of living embryos as a nondestructive indicator of EROD activity. This fluorescence was observed only in embryos exposed to the EROD substrate and Ah receptor agonists and was consistent in fluorescence characteristics with the EROD product, resorufin. Aryl hydrocarbon receptor‐agonist exposures at sublethal concentrations in the parts per billion range, produced significant increases in EROD fluorescence in embryos as young as 3 d postfertilization. These findings are consistent with the conclusion that this fluorescence method is a specific and sensitive nondestructive indicator of Ah receptor‐mediated effects in an embryonic fish. As such, this simple method may be useful for assessing effects of environmental contaminants on the early development of fishes and to link molecular indicators with organism‐level responses.
Ultraviolet light can activate certain polycyclic aromatic hydrocarbons (PAHs), inducing the prod... more Ultraviolet light can activate certain polycyclic aromatic hydrocarbons (PAHs), inducing the production of free radicals. In biological organisms these free radicals destroy tissues, causing up to a 4,000 fold increase in toxicity. This dramatic response is a potential marker for PAH contamination in environmental samples. Ultraviolet enhancement of toxicity has ecological relevance as well. An oil spill can release large amounts of PAHs into the marine environment. Oil spill assessments to date have not included observations of any phototoxic effect on pelagic larvae or juveniles of benthic or epibenthic invertebrates. In this study, larvae and juveniles of the bivalve, Mulinia lateralis and juveniles of the mysid shrimp, Mysidopsis bahia were exposed to individual PAHs, as well as the water accommodated fractions of several petroleum products to verify the ability of this method to detect PAHs in environmental samples, and to determine if phototoxicity is a concern during and afte...
The common loon, Gavia immer , is considered an emblematic and ecologically important example of ... more The common loon, Gavia immer , is considered an emblematic and ecologically important example of aquatic-dependent wildlife in North America. The northern breeding range of loons has contracted over the last century, presumably as a result of habitat degradation from human ...
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