ECO-FUNCTIONAL BENTHIC BIODIVERSITY ASSEMBLAGE PATTERNS IN THE GUINEA CURRENT LARGE MARINE ECOSYSTEM

ABSTRACT Functional diversity, an important component of biodiversity, has in recent years engaged global attention. This is in great part due to the mechanistic understanding achieved from functional diversity studies in the face of accelerated global biodiversity changes ascribed primarily to anthropogenic drivers. The exigency of the situation has stimulated biodiversity-ecosystem functions (B-EF) studies to elucidate ecosystem processes and services that are at threat notably in the marine ecosystem. The marine benthos is the largest ecosystem on earth and supports the highest phylogenetic diversity but has rather witnessed comparatively low attention in the B-EF studies than the terrestrial counterpart. This thesis is aimed at i) quantifying benthic functional diversity (using biological trait analysis) and assemblages along abiotic gradients in the Guinea Current Large Marine Ecosystem (GCLME); and ii) examining the impact of bottom trawling for demersal fishes on the functional structure of epibenthic fauna along bathymetric gradients. In achieving the above-mentioned objectives, epibenthic fauna of bottom trawl samples were collected from Ghana to western Nigeria‘s continental shelf in 2003. Further, macrobenthic infauna and abiotic samples were collected from coastal waters of Guinea Bissau to Gabon in 2007. Each processed dataset was treated as a stand-alone in the thesis. In decomposing the assemblage patterns, suites of univariate and multivariate statistics were employed. The results indicated 381 macobenthic species comprising polychaetes (61.15% richness and 55.15% abundance), crustaceans (18.64% richness and 28.02% abundance), molluscs (9.19% richness and 2.23% abundance), echinoderms (2.63% richness and 1.84% abundance) and ‗others‘ (8.39% richness and 12.76% abundance). Functional diversity analysis indicated spatial differences in eco-functional traits namely small body size, solitary lifestyle, burrowing and deposit-feeding, and these traits dominated the assemblage especially from Ghana to Benin. The results suggest that these areas are potential surrogates of allochthonous organic material possibly driving pelagic productivity that is translated to the benthos. Significant (p