Abstract

Most of crustacean and fish species living in Caribbean rivers are diadromous (travel between salt and freshwater). Riverine fish and macro-crustacean species spend a significant part of their life cycles in mangrove or open sea. In the Caribbean, rivers and sea have close functional relationship. Stable isotope analysis was used to quantify the relative importance of riverine food sources during the inland part of life cycles of Palaemonidae, Atyidae, Xiphocarididae, Gobiidae, Eleotridae and Anguillidae entering stream food web from open sea. Results revealed that the epilithic biofilm is largely exploited by species. Biofilm was then specially investigated in nine rivers of Guadeloupe Island. The respective proportion and the physiology (fluorescence) of biofilm components were assessed by flow cytometry in relation to physicochemical parameters and pesticides water content. Epilithic diatoms were identified and counted. Our results show that, in Guadeloupe, the epilithic diatoms community is mainly correlated with sulfates and organic matter concentrations rather than pesticides content. Such community seems to be primarily sensitive to water characteristics as those originating from hydrothermal sources. These results address the question of their use in ecological diagnostic of pesticide contamination in Caribbean region, without reference to geographical or geological microscale variations.

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