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Pesticides sprayed on farmlands can go into rivers and estuaries by transportation through water runoff; and are sufficiently persistent in the environment to be toxic to aquatic communities. During the summer of 2004, a series of experiments were conducted on the behaviour of the amphipod Corophium volutator exposed to six pesticides namely, Endosulfan I + II, Azinphos methyl, Carbofuran, Chlorothalonil, Atrazine and Hexazinone over a wide range of concentrations. Endosulfan was the only pesticide out of the six tested showing properties as an attractant at lower concentrations and as a repellent at higher concentrations. The behavioural response of the amphipod Corophium volutator to the pesticide endosulfan was further investigated. The experiments were repeated to observe; scale of movement, effect of weathered pesticides and behaviour over three concentrations of contaminated sediments with changes in time. Lipid percent relative to dry animal mass was also examined as a potential biological effect representing changes in lipid metabolism. The pesticide partitioning for >sediment organic carbon water= was calculated based on the published octanol water partitioning coefficient. Based on these results, possible concentrations of endosulfan entering the Wilmot River estuary were estimated. Behavioural experiments on Corophium sp., changed with time survival rate was low. The animals were less resistant to manipulation in the winter consequently, sampling time should be recorded and small animals as well as pregnant females should not be used. Lipid extractions revealed a higher lipid percent for exposed animals and varying with time. The partition coefficient calculation for organic carbon in comparison with water showed a higher affinity for organic enriched particles. The concentrations used for behavioural experiments were realistic compared to the exposure levels expected in an estuarine environment. Hence, a long term research goal would be to determine if commonly used pesticides in the conventional potato industry have an effect on the marine community of an estuary.

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Pages: 74
Supervisors: J. Hellou / David Scott