Effects of pyrethroid insecticides in urban runoff on XXXX , steelhead trout, and their invertebrate prey.

@entity137 @entity11806
UNASSIGNED: Pyrethroid insecticides can affect salmonids either indirectly through @entity137 to their prey or directly by @entity137 to the fish themselves. In support of a study on pyrethroid impacts to @entity11806 and steelhead trout in the American River (Sacramento, California, USA), 96-h median effective concentration (EC50) and median lethal concentration (LC50) values for the pyrethroid bifenthrin were determined for taxa not traditionally used for @entity137 testing but of interest as salmonid prey, including a chironomid, caddisflies, mayflies, and stoneflies. A laboratory was constructed on the banks of the American River to expose macroinvertebrates, @entity11806 , and steelhead trout to flow-through river water containing urban runoff during storm events. Bifenthrin from urban runoff was found in river water following 5 rain events, reaching 14.6   ng/L. Mortality to the exposed salmonids was not observed, and sublethal effects were not seen in vitellogenin or sex steroid levels. Indirect effects via @entity137 to salmonid prey are possible. Mortality to Hyalella azteca, a potential prey, was observed in every event tested, and peak bifenthrin concentrations were comparable to the 96-h EC50 of the caddisfly, Hydropsyche sp., the most important prey species on a biomass basis for American River @entity11806 . The other invertebrates tested had EC50s exceeding bifenthrin concentrations seen in the American River, though could potentially be at risk at concentrations previously reported in smaller urban tributaries. Environ Toxicol Chem 2014;9999:1-9.    2014 SETAC.
