Composition and Structure of Aquatic Macroinvertebrate Communities in Mining Areas Streams (Côte d’Ivoire, West Africa)

Abstract

The existence of mining areas for decades could potentially affect aquatic environments and human health. This study allowed assessing the effects of mining activities on streams in three mining areas (Hiré, Lauzoua and Tortiya). Macroinvertebrates were collected on eight campaigns at eight stations using a hand-net, an Ekman grab and surber net. Environmental variables were recorded also. In this study the conductivity values were higher in the locality of Hiré. It was between 154.2 μS / cm (Tchindégri station) and 1753 μS / cm (Tributary Gbloh station). The highest temperature values were recorded in the stations of Tortiya locality (24 ^o C: Bou 2; 33.1 ^o C: Bou 1). A total of 184 taxa distributed among nine classes, 20 orders, 80 families and comprising 14 401 individuals were recorded. Insecta were the most diversified class in macroinvertebrate community (84% of taxa collected, eight orders and 59 families). Ecological indices (Shannon Weiner, rarefied richness, Pielou’s evenness) were significantly low at Lauzoua (N'Téko station) and Hiré (Tributary Gbloh station) (Mann- Whitney test, P <0.05). Ecological indices showed no significant variation between the stations of the locality of Tortiya. The PCA had grouped the stations into four clusters. Conductivity, ammonium, phosphate, nitrites, and nitrates were significantly higher (Mann- Whitney test, P < 0.05) in cluster I (Tributary Gbloh station) Compared to other clusters. Eight taxa (Limnius sp., Liberonautes chaperi, Gordius sp., Phyllogomphus sp., Orectogyrus sp., Bezzia sp., Adenophlebiodes, Parasedodes sp.) were specific to Tchindégri station (Hiré) and six taxa (Naucoris sp., Amphiops sp., Hydrobius sp., Pseudobagous longulus, Culicinae and Gomphus sp.) were associated to the Bou 1 and Bou 2 stations (Tortiya).