Project ID: 2003MS19B

Title: Chemical Mixtures: Consequences of WNV Eradication on Water Quality

Project Type: Research

Focus Categories: Sediments, Toxic Substances, Water Quality

Keywords: ecosystems, mixtures, pesticides, residues, sediments, toxic substances, water quality

Start Date: 03/01/2004

End Date: 02/28/2005

Federal Funds: $16,540

Non-Federal Matching Funds: $33,077

Congressional District: First

Principal Investigator:
Marc Slattery

Abstract

Recent outbreaks of West Nile Virus (WNV) throughout the United States, and particularly in the Mississippi Valley States, have spurred plans for vector (= Culex mosquito) eradication using a variety of control insecticides. Via direct or indirect routes these compounds enter the aquatic environment where they become part of water and sediment matrices. Through direct contact, respiration or indirect ingestion non-target organisms are exposed to persistent and transient anthropogenic compounds and their mixtures. Individually or as mixtures, acting additively or synergistically, these compounds can directly affect adult and juvenile life stages of aquatic organisms. Besides direct effects some anthropogenic compounds found in aquatic matrices are known to bioaccumulate and biomagnify. At the present time, there is limited knowledge regarding effects of WNV vector control compounds in mixtures. Evaluating water quality and aquatic habitat are critical to an overall assessment of vector eradication programs.
The overall goal of the proposed research is to evaluate “real-world” chemical mixtures with toxicological effects not predicted from single chemical toxicity experiments. The amphipod Hyalella azteca and the water flea Daphnia magna will be exposed to mixtures of three model compounds: methoprene, a mosquitocide, and two regionally persistent anthropogenic compounds, chlorpyrifos and methylmercury. Bioconcentration data along with toxicological indices will be used to determine the critical body residue threshold concentrations at which toxicological effects occur. In the first year (2003-04) toxicological effects of the individual model compounds that have yet to be characterized will be assessed. In addition, we will develop analytical procedures to quantify in situ concentrations of model compound in regional water and sediment matrices. The second year (2004-05) will be spent toxicologically assessing mixtures of model compounds. Additional investigations will explore the impacts of pre-exposure stress on the ability of the model organisms to cope with a new toxicant. Finally, in year three (2005-06), bioconcentration data will be used to determine critical body residues. Model compounds in natural water and sediment matrices and residuals in model organisms will be quantified.

Progress/Completion Report PDF