Spatial Distribution of Lake-water Insects in Minna, North central Nigeria: Bio-indication of Water Quality.

Abstract

This paper reports on a study to elucidate the ecological state and water quality of fresh water lakes in Minna, Nigeria, and generate baseline information for their sustainable management. Aquatic entomo-faunal indicators of water quality were assessed for spatial variations in species composition and relative abundance among four lakes in the area, following standard procedures. The results indicated the occurrence of 16 insect species, belonging to five Orders; in order of abundance, Coleoptera > Hemiptera > Diptera > Odonata > Orthoptera, in the lakes. The dominant insect species encountered included, Locris ruben (23.23%), Chironomus sp. (14.81%), Helochares sp. (14.13%), Orectogyrus sp. (12.23%), Epilachna similis (11.96%), etc. The total numbers of insects collected from the four lakes varied significantly (P < 0.05), ranging from 4.89% in Bosso Pyata lake to 51.49% in Bosso Gabas lake. Likewise, the proportional distribution of the individual insect species within a lake differed significantly (P < 0.05). The most versatile taxa were Diptera and Odonata, being present in all lakes while, Orthoptera was the most restricted, recovered only from Bosso Gabas and Tagwai lakes. While all five insect Orders encountered during the study period were present in Bosso Gabas and Tagwai lakes, Bosso Pyata lake was the least productive, harbouring only two Orders. These results were discussed from the ecological standpoint of probable pollution status of the lakes, and it is hoped that the findings will guide the managers of the lakes in taking informed and justifiable actions.