Submitted to: Bulletin of Environmental Contamination and Toxicology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/16/2007
Publication Date: 8/3/2007
Citation: Moore, M.T., Lizotte Jr, R.E., Smith Jr, S. 2007. Responses of Hyalella azteca to a pyrethroid mixture in a constructed wetland. Bulletin of Environmental Contamination and Toxicology. 78(3-4):245-248. Interpretive Summary: Pesticides associated with agricultural runoff can contaminate downstream aquatic receiving systems, such as rivers, lakes, and streams. Several best management practices have been studied as a means to reduce the detrimental effects of pesticides in runoff, including constructed wetlands. This study examined the effects of lambda-cyhalothrin and cyfluthrin, two pyrethroid insecticides, on the survival of a non-target aquatic organism that may be found in constructed wetlands. Results indicated that non-target aquatic organisms found in constructed wetlands used for pesticide mitigation may be affected by inflow concentrations; however, it is important to remember that these wetlands are not intended for aquatic organism habitat purposes. Constructed wetlands continue to serve an important role in the processing of pesticides associated with agricultural runoff.
Technical Abstract: Lambda-cyhalothrin and cyfluthrin are pyrethroid insecticides with widespread use in the intensively agricultural area of the Mississippi Delta. As a result, these insecticides have the potential to contaminate non-target aquatic environments through storm water runoff. Water, sediment, and leaf litter were collected at 1 d, 7 d, 13 d, 27 d, 42 d, and 61 d (water and sediment only) after initial pesticide dosing. Chemical analyses and toxicity assessments using the benthic macroinvertebrate, Hyalella azteca, were conducted on collected samples. Hyalella survival in aqueous samples significantly decreased in all three wetland cells after pyrethroid dosing. No decrease in aqueous toxicity was observed during the 61 d exposure, even though there were significant decreases in pyrethroid concentrations. Survival in pyrethroid contaminated leaf litter elicited similar responses as aqueous samples, but with greater effects concentrations. Pyrethroid contaminated sediment produced temporal variation with regard to Hyalella survival; however, effects were less than those observed in water or leaf litter samples. Toxicity assessments indicate sediment and leaf litter bound pyrethroids can move from contaminant sink to source affecting non-target aquatic organisms weeks to months after entering a constructed wetland.