Effects of sediment input on aquatic animal communities in new Calabar river, Rivers state, Nigeria

Abstract

The effects of sediment input on aquatic animal communities in New Calabar River in Rivers State Nigeria were studied. Samples of the sediments were collected using Ekman's grab. Sediments were seived through various mesh sizes until fme silt was obtained. Macroinvertebrates were collected using scoop nets. The water temperature, pH, dissolved oxygen content and transparency were measured from September to December, 2006. The results indicated that temperature and dissolved oxygen content were within tolerable range for the animals. Silt was gradually being deposited in the River and some parts are silted up resulting in loss of water and decrease in the population of macroinvertebrates such as Biomphalaria sp, Lymnae sp and Asphatharia sp. In addition the texture of the silt determiners the abundance of macroinvertebrates hence the increase in the population in the month of Nov, while Sept(43%), Oct(6.6%) and Dec(1.5%), had a gradual decrease that is inversely proportional to the siltation of the river.

KEYWORDS: Silt, freshwater, benthic, Molluscs and sediments.