The Effects of Environmental Toxicants on Fundulus heteroclitus behavior and p - glycoprotein activity

Abstract

Killifish (Fundulus heteroclitus) inhabit coastal salt marshes where they may be exposed to toxic runoff from land. They are an important mid – level organism in the salt marsh food web, feeding on small macroinvertebrates and in turn providing food for wading birds and larger fish. Changes in killifish populations, due to toxicant exposure, may have dramatic effects on the entire salt marsh food web. Killifish were collected from tidal creeks on Sapelo Island, GA. After a seven day acclimation period, fish were exposed to environmentally relevant concentrations of the insecticide malathion for 4 or 48 hours and then fed white shrimp ad libitum for 20 minutes. Fish exposed to malathion consumed less shrimp than unexposed control fish, with a general decrease in consumption as the malathion concentration increased. Malathion – treated fish also had diminished optomotor activity, suggesting that malathion, a potent neurotoxin, was having an adverse effect on the killifish nervous system. Killifish feeding studies are currently being conducted using other environmental contaminants. Additionally, we are measuring the titer of the cell membrane transport protein p – glycoprotein, known to pump organic toxicants from liver cells, to link exposure consequences at the cellular and behavioral levels.