Recherches sur la contamination par les pesticides d’organismes marins des réseaux trophiques récifaux de Polynésie française

Abstract

Researches on the contamination by pesticides of marine organisms within coral reef trophic webs in French Polynesia. Researches addressed in this paper have been carried out in the framework of a survey of the pollution levels by pesticides in French Polynesia coral reefs. A ubiquitous contamination has been shown up of critical organisms from various levels of the trophic web. Such a contamination occurs even in remote areas such as for example some atolls from the Tuamotu Archipelago where agricultural activities are very restricted. On one hand, the occurrence of organochlorine insecticides is shown widespread. Especially worrying is our finding of chlordecone (képone®) widely present in all organisms investigated, particularly in fishes, which are commonly consumed by the local inhabitants. Some concerns arise from these data as the average residence time of chlordecone in sediment numbers in thousands of years. On the other hand, analyses have demonstrated a pervasive contamination of coral reefs trophic webs by various major families of herbicides, namely chloroacetamide and triazine derivatives, as well as diuron. These findings are worrying with respect to the coral reefs ecosystems health, especially since their functioning is strongly dependent on the Symbiodinium zooxanthellae symbiosis with hermatypic coral, as the Symbiodinium Dinoflagellates that have proven especially sensitive to these families of herbicides. These can partially inhibit their photosynthetic activity at concentrations lower than one part per billion in seawater.