Macroinvertebrate Communities Associated with Hydrilla verticillata (Royle, 1839) and Relationship with Environmental Factors in Ono Lagoon, Southeast of Côte d’Ivoire

The macroinvertebrates associated with Hydrilla verticillata was studied in Ono lagoon, South-eastern of Côte d'Ivoire. Monthly samples of macrophytes with their associated macroinvertebrates were collected in upstream, centre and downstreamusing a Van veen grab of 0.314 m2 internal area. The environmental variables (temperature, transparency, depth, conductivity, TDS, pH, dissolved oxygen, , , and ) were also recorded. A total of 71 taxa belonging to 28 families, 11 orders, 05 classes and 03 phyla of which 40 taxa were recorded in upstream, 45 taxa in centre and 44 taxa in downstream. Insects numerically dominated the capture, comprising 91.55% of the collectedtaxa with Odonata and Coleoptera being the most diverse and abundant groups. The density was higher in upstream (1407ind. per 100 g d.w.) and lower in downstream (1062 ind. per 100 g d.w.), whist theLibellulidae and Corduliidae exhibited the highest density communities. The rarefied richness did not show spatial variation but vary significantly between seasons. The Evenness did not show spatial and seasonal variations. However, Shannon diversity index varied significantly between sites and seasons. From the results of RDA analysis, conductivity and pH showed a strong environmental gradient and had a structuring effect on macroinvertebrate communities.