Morphological and molecular characterization of bivalves with respect to their diversity and distribution in Murchison Bay, Lake Victoria, Uganda

Abstract

This study was designed to characterize bivalves in Murchison Bay using morphological and molecular approaches. The diversity and abundance of bivalves and the effect of abiotic factors were also determined from eight sites of the bay (Kaazi, Gerenge, Gaba Water Works, Luzira Port Bell, Nakivubo Inlet, Kawuku, Tende and Katomi). Sediment and water samples were collected using an Ekman grab and a vertical column sampler, respectively. In-situ measurements of water physico-chemical parameters were taken using Hach multi-meter probe, while sediment type and size were determined using graded sieves. Bivalves’ morphological characterization was done using shell features, and molecular characterization using mitochondrial molecular markers. Eight species recorded during the study were; Corbicula fluminalis, Corbicula sp., Coelatura mocenti, Coelatura hauttecoeurri, Sphaerium sp., Byssanodonta sp., Mutela sp. and Aspatharia sp. Molecular characterization of C. hauttecoeurri revealed high genetic diversity (H=0.996, π=0.005), while that of C. fluminalis was low (H=0.533, π=0.001). This could be due to presence of different lineages in C. hauttecoeurri and androgenetic reproduction behaviour in C. fluminalis, respectively. Sphaerium sp. was dominant in seven of the eight sampling sites, attributable to its generalistic behaviour, i.e. the ability of adapting to a wide range of environmental conditions. Sediment type was the most important factor affecting the diversity and distribution of bivalves in the bay. These results showed that Murchison Bay has a diverse community of bivalves, therefore, more studies on their characterization and ecology should be carried out beyond the bay.