Impacts of benthic coarse particulate organic matter variations on macroinvertebrate density and diversity in the Njoro river, a Kenyan highland stream

Abstract

An investigation to assess the relationship between coarse particulate organic matter (CPOM) and macroinvertebrate communities was undertaken in the Njoro River, Kenya during 2010. Significantly lower macroinvertebrate densities and diversities were observed in study sites with low Coarse Particulate Organic Matter (CPOM) content. The Mugo study site had the highest CPOM content and macroinvertebrate density and diversity. The unidentifiable detritus category (i.e. small CPOM fragments) had the highest influence on macroinvertebrate taxa whereas twigs had the least influence. The benthic samples were dominated by detritivores, but no shredders were recorded. Our results suggest that CPOM is an important determinant of the macroinvertebrate assemblages in streams. Given this, we believe that it is important to conserve tropical stream riparian vegetation due to their important role as a source of CPOM in streams.

Keywords: Benthic organic matter, Kenya, riparian vegetation, macroinvertebrates