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Caractérisations physico-chimique et biologique des cours d'eau de la Nouvelle-Calédonie. Proposition d'un indice biotique fondé sur l'étude des macroinvertébrés benthiques

Résumé : Forty-one stations located on 14 rivers spread over the whole of New Caledonia were periodically sampled from October 1996 to October 1997. Benthic invertebrate samples were taken at each of the stations, then identified and counted in the laboratory. . At the same time, water samples were analyzed at each study station. The physico-chemical nature of the waters of the rivers of the mainland is strongly influenced by the drained geological substrates. Organic pollution is generally not very significant in the territory, the highest concentrations of nitrates, ammonium and organic matter are measured in the rivers located near certain villages, tribes or towns, in the agglomeration of noumea and level of the lower courses of the rivers of the west coast. A physico-chemical typology of the study stations based on their geographic location, land use and the geological nature of the rocks was highlighted using multivariate analyzes. The benthic macrofauna of rivers is dominated by insects. The environments most conducive to the development of benthic macrofauna and which present the maximum specific diversity are forest streams. In contrast, the watercourses draining altered peridotites and far from any human occupation are characterized by less diversified and less abundant benthic populations due to their low organic matter content. In addition, some taxa show a generic and specific endemism linked to the peridotitic substrate like terrestrial insects. A biotypology of the study stations has been defined, based on the same criteria as those of the physico-chemical typology. Land use, riverine vegetation and the geological nature of watersheds represent the main factors explaining the distribution and distribution of benthic macrofauna in rivers. An original biotic index specific to the rivers of New Caledonia is proposed in this work. The biotic index of new caledonia (ibnc) makes it possible to detect organic pollution in current environments. It refers to 62 frequent and easily identifiable taxa which have been assigned a score according to their sensitivity to organic matter.
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Soumis le : mercredi 23 décembre 2020 - 02:25:02
Dernière modification le : mercredi 6 janvier 2021 - 03:08:45

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  • HAL Id : tel-03086900, version 1

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Nathalie Mary. Caractérisations physico-chimique et biologique des cours d'eau de la Nouvelle-Calédonie. Proposition d'un indice biotique fondé sur l'étude des macroinvertébrés benthiques. Interactions entre organismes. Université Française du Pacifique, 1999. Français. ⟨NNT : 1999PACI0027⟩. ⟨tel-03086900⟩

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