Neurotoxic and behavioral effects of carbaryl and glyphosate pesticides on killifish (Fundulus heteroclitus)

Abstract

Neurotoxic pesticides may enter tidal creeks and disrupt food webs. The current study examined the effect of two pesticides, carbaryl (Sevin) and glyphosate (Round – up), on feeding in Fundulus heteroclitus (killifish), an important member of the salt marsh food web. Thirty fish were exposed to each pesticide at the LC50 (a concentration lethal to 50% of fish exposed for 96 hours) or half of the LC50 concentration for 24 hours, without food, prior to testing. Fish were individually placed in a t-maze and the time it took them to find and consume food was recorded. Shrimp pellets were placed in alternating arms of the t-maze for each trial. Fish exposed to pesticides were either unable to consume pellets or took significantly longer to ingest pellets than control fish. This occurred in fish exposed to both LC50 and half LC50 concentrations, although the effect was more pronounced at the higher concentrations. In a subsequent recovery control study, fish exposed to half LC50 concentrations were able to resume pre – exposure feedings rates within 5 days of toxicant removal. Based on these results, both carbaryl and glyphosate adversely affect the killifish’s feeding ability, which can have consequences throughout the salt marsh food web.