Distributional Patterns of Gastropoda Upstream and Downstream of Bujagali Hydropower Project along the Upper Victoria Nile

Abstract

To better understand the gastropod community dynamics of fresh water snails in the Upper Victoria Nile (UVN), the spatial and temporal abundance changes in gastropod assemblage were assessed biannually from April 2006 to April 2021 at three transects. Biannual abundances of gastropoda were obtained by a ponar grab to examine changes in their community structure in relation to Bujagali Hydropower Project (BHP). The gastropod community consisted of nine speciesbelonging to five families (Thiaridae, Viviparidae, Ampullariidae, Bithyniidae and Planorbidae). Pulmonate species registered five species <i>(Anisus natalensis, Gyraulus sp., Segmentorbis sp., Bulinus sp. and Biomphalaria chaonomphola)</i>. Two of the pulmonates <i>(Bulinus sp. and B. chaonomphala)</i> are schistomiasis vectors. The pulmonates <i>(A. natalensis, Gyraulus sp., Segmentorbis sp.)</i> were rare and intermittently occurred with abundances up to 47 ind.m-2. Four prosobranch species <i>(Gabbia humerosa, Pila ovata, Melanoides tuberculata and Bellamya unicolor)</i> were encountered. Of these prosobranchs, <i>P. ovata</i> was the rarest while <i>M. tuberculata</i> and <i>B. unicolor</i> were the commonest. The gastropod community in the UVN was characterised by prosobranchs-dominated abundance which over the 16-year monitoring period often registered peak densities of > 1000 ind.m2. The inter-site Percent Similarity Index (PSI) (94-100%) indicated a high degree of similarity of gastropod community across the sites.

Sustainability of Fish-Hydropower Dam Interaction: A Case Study of River Nyamugasani ecosystem, Albertine Graben

“…Environmental factors such as, conductivity, dissolved oxygen, phytoplankton and micro-invertebrates, crucial for fish distribution, not included in these samplings. Macro invertebrates, as fish food (Massa et al, 2021;Busulwa, 1989;Bassa et al, 2019;Sekiranda et al, 2004), may contribute to fish distribution along the Nyamugasani stretch.…”