MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(GRO-1117-749351) An evaluation of OCP effects in fathead minnows: Comparison of embryo and maternal exposure.

Huge, D^{1, 2}, Gross, T^{1, 2}, ¹ USGS-FISC-CARS, Gainesville, FL, USA² University of Florida, Gainesville, FL, USA

ABSTRACT- Previous studies from this laboratory have documented decreased reproductive efficiency and altered hormone concentrations in wild populations of American alligators (Alligator mississippiensis) and largemouth bass (Micropterus salmoides) from sites contaminated with organochlorine pesticides (OCPs). OCPs bioaccumulate significantly in fish. The purpose of this study was to determine whether adverse effects are caused by direct embryo toxicity or are due to OCP-induced effects on maternal reproductive physiology. The study investigated maternal transfer of the OCPs dichlorodiphenyldichloroethylene (DDE), dieldrin, chlordane, and toxaphene from adult fathead minnows (Pimephales promelas) to egg and larvae. Adult female fathead minnows were dosed at rates of high, middle, and low. The high dose was a complex mixture comparable to concentrations found in blue tilapia (Oreochromis aurea() from a historically contaminated lake in central Florida. The middle dose was 50% of the high dose, and the low dose was 25% of the high dose. The frequency of spawns, the number of eggs laid per spawn, the number of eggs hatched, as well as the number of larvae survived to day 14 were recorded. The second portion of the experiment investigated the effects on hatch and mortality rates of fathead minnow eggs nanoinjected with comparable concentrations of OCPs. The third portion of the experiment investigated whether fathead minnow eggs exposed aqueously to comparable doses had an adverse effect on hatch and mortality rates. Preliminary analysis indicates maternal exposure to OCPs had a decreased effect on the frequency of spawns. Preliminary analysis also indicated fathead minnow eggs nanoinjected with various concentrations of DDE had a decreased effect on hatch rate, and a decrease in survivorship. In conclusion, wild populations of fathead minnows maternally exposed to OCPs may spawn less frequently. Eggs and embryos from wild populations directly exposed to OCPs may have a decreased hatch rate and decreased survivorship.

Key words: Organochlorine pesticide, Fathead minnow, mixtures, reproduction