Diversity of the chironomidae (diptera) of river Niger related to water pollution at Niamey (Niger)

Abstract

This paper presents the first results on the water quality of the River Niger at Niamey based on the Chironomidae. Artificial substrata of stones covered with galvanized wire netting were used for collecting the chironomid larvae. Water samples were taken for physicochemical analysis. Twenty taxa of chironomidae were collected. Among these, Chironomus gr. plumosus represented51% and Microchironomus sp. 26% of all larvae collected. The distribution of Chironomidae throughout the river showed differences between the sampling stations. Organic pollution and nutrients loading were the main factors explaining the differences in spatial distribution. Some taxa, e.g. Chironomus gr. plumosus and Microchironomus sp. are positively correlated to those factors, while others as Tanytarsini, Nilodosis sp., Micropelopinae and Procladius sp. are negatively correlated. According to these results, Chironomidae appear an excellent tool for the assessment of the biological quality of western African rivers.

Keywords: Chironomidae, River Niger, Niamey, water quality