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Variability in acute to chronic ratios (ACRs; median lethal or effect concentration divided by chronic value) has been of continuing interest in aquatic toxicology because of the reliance on ACRs to estimate chronic toxicity for chemicals and species with known acute toxicity data but with limited or no information for chronic toxicity. To investigate the(More)
Polycyclic aromatic hydrocarbons (PAHs) can cause a variety of effects in early life-stages of fish that have been chronically exposed as embryos, including mortality, deformities, and edemas. Mechanistic models of the chronic toxicity of complex mixtures of PAHs in fish have not been reported, with the exception of a previously untested model based on the(More)
Chlorpyrifos is a broad-spectrum organophosphorothioate insecticide with a principal mechanism of toxicity by inactivation of acetylcholinesterase at nerve junctions. Unlike certain organochlorine pesticides, chlorpyrifos is relatively nonpersistent (Racke 1993), and its principal degradation products are less toxic than the parent chemical. Species(More)
The present study describes the acute toxicity of eight commercial oil dispersants, South Louisiana sweet crude oil (LSC), and chemically dispersed LSC. The approach used consistent test methodologies within a single laboratory in assessing the relative acute toxicity of the eight dispersants, including Corexit 9500A, the predominant dispersant applied(More)
The parr-smolt transformation (smoltification) of juvenile anadromous salmonids involves a morphological, physiological and behavioural metamorphosis of the fish from a freshwater-adapted form to a salt-water-adapted form. Several endocrine glands are activated during the period of smoltification, including pituitary, thyroid, and interrenal tissues. The(More)
Photoenhanced toxicity is the increase in the toxicity of a chemical in the presence of ultraviolet light (UV) compared to a standard laboratory test conducted with fluorescent lighting (minimal UV). Oil products, weathered oil, and specific polycyclic aromatic compounds present in oil are 2 to greater than 1000 times more toxic in the presence of UV. The(More)
Associations between tissue residues and toxicity to aquatic organisms were examined to evaluate the applicability of the critical body residue (CBR) approach across different chemical classes. Chemical classes and mode of action categories evaluated included narcotics (polar and nonpolar), excitatory agents, AChE inhibitors, reactives/irritants, CNS(More)
The mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity and as an alternative to chemical class-based predictive toxicity modeling. However, the development of quantitative structure activity relationship (QSAR) and other models has been limited by the availability of comprehensive high quality MOA and toxicity(More)
After nearly 3 decades of decline, the western stock of Steller sea lions (SSL; Eumetopias jubatus) was listed as an endangered species in 1997. While the cause of the decline in the 1970s and 1980s has been attributed to nutritional stress, recent declines are unexplained and may result from other factors including the presence of environmental(More)