Aquatic macroinvertebrate assemblages associated with root masses of water hyacinths, Eichhornia crassipes (Mart.) Solms-Laubach, 1883 (Commelinales: Pontederiaceae) in Taabo Lake, Ivory Coast

摘要

We examined aquatic macroinvertebrates associated with Eichhornia crassipes roots at five sampling sites in Taabo Lake. An average density of 1644 individuals (ind.)/m(2) was recorded. In total, 68 macroinvertebrate taxa belonging to 34 families and 14 orders were identified. Among these, Insecta was predominant (77.94%). The highest densities were recorded at Taabo cite during both rainy and dry seasons. Taxon diversity differences were not observed among all stations according to a Kruskal-Wallis test. High densities of predators were recorded. Next most prevalent in the trophic structure were detritivores. Indicator taxa analysis, using the Indval method, showed that stations upstream of the lake were characterized by eight taxa, while 11 appeared as indicators of the station near the dyke. Predators and herbivores dominated within those indicators. Sites near bays were distinguished by 18 indicator taxa with a predominance of predators and detritivores. Conductivity, NH4+, temperature, PO43-, turbidity and dissolved oxygen were parameters that strongly influenced the macroinvertebrate community.