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(19-30) Effects of pesticide contamination on the ecology of Costa Rican streams in the vicinity of banana and pineapple plantations. Gustafsson, Kerstin*,1, Wendt-Rasch, Lina2, Englund, S1, Plantman, Peter1, Swahn, G1, 1 Systems Ecology, Stockholm university, Stockholm, Sweden2 Ecology building, Lund university, Lund, Sweden ABSTRACT- Most studies on ecological effects of pesticides have been performed in temperate regions and little is know about the effects of pesticide stress on tropical ecosystems. Nevertheless, very large quantities of various pesticides are used in tropical agriculture. During the cultivation of bananas and pineapples considerable amounts of herbicides as well as insecticides are used and pesticide residues have regularly been documented in streams in the vicinity of banana plantations. In this study, the occurrence of pesticide stress was investigated in running waters in two types of tropical agricultural regimes, banana and pineapple plantations. The periphytic algae of presumed exposed and un-exposed streams were subjected to short-term toxicity test in order to evaluate the PICT-response (Pollution-Induced Community Tolerance) to the herbicides diuron and ametryn. Samples of sediment-living nematodes in the streams were similarly subjected to short-term toxicity test in order to detect PICT in response to the insecticides/nematicides chlorpyriphos and cadusafos. Alginated beads with Selenastrum capricornutum were used to evaluate the toxicity of the stream water to algal growth both under field conditions and in the laboratory. Similarly, juvenile and adult Daphnia magna were used to investigate the toxicity of stream water in bioassays performed in the field as well as in the laboratory. Key words: tropical ecosystems, pesticides, ecotoxicity |
