Effect of microplastic distribution on diversity of microbenthic fauna of Sub-Saharan Africa tropical mangrove ecosystems

Abstract

Microplastic (MP) pollution poses a growing threat to mangrove ecosystems, particularly in tropical regions where ecological and socioeconomic dependencies are high. This study investigated MP contamination in sediment, water, and microbenthic fauna across selected mangrove sites (Ikpa River Basin and Qua Iboe River Estuary) in Sub-Saharan Africa. Using standardized sampling and spectroscopic techniques (μFTIR and SEM), MPs were detected in all sample types, with higher concentrations near urban and industrial zones. Polymer analysis identified polyethylene, polypropylene, and polystyrene as dominant types. A strong negative correlation (r = -0.72, p < 0.05) was found between MP load and the Shannon-Wiener diversity index (H′) of microbenthic fauna. Sites with elevated MP levels showed reduced species richness and lacked sensitive taxa such as polychaetes and amphipods. We observed MP bioaccumulation and histopathological effects, including gut obstruction and epithelial damage, in Capitella capitata and Hyalella spp. These findings highlight the urgent need for pollution control and conservation strategies in African mangrove habitats.