Assessment of Seagrass Bed Extent and Condition in the Coastal Zone of Bayelsa State

Seagrass beds are among the most productive coastal habitats, providing nursery grounds for juvenile fish and crustaceans, carbon sequestration services, and sediment stabilisation functions. This study assessed the spatial extent, species composition, shoot density, and ecological condition of seagrass beds in the shallow coastal zone of Bayelsa State, South South Nigeria. Field surveys were conducted during low tide at four sites using a combination of transect-quadrat methods and GPS-aided mapping. Seagrass shoot density, leaf area index, and biomass were measured within 0.5 by 0.5 metre quadrats. Associated fauna were sampled using fine mesh push nets, and water quality parameters including turbidity, salinity, light penetration, and dissolved nutrients were recorded. Three seagrass species were identified: Halodule wrightii, Thalassia hemprichii, and Cymodocea nodosa. Halodule wrightii was the most abundant species, particularly in shallower, more turbid zones. Total seagrass coverage was mapped at approximately 1.8 square kilometres across all surveyed sites. Shoot density varied significantly between sites, with the highest values at the least turbid station. Elevated turbidity at sites near oil facility discharge points was associated with reduced shoot density and partial leaf degradation. Epifaunal diversity was positively correlated with seagrass shoot density. The study provides a baseline assessment of seagrass resources in Bayelsa and identifies turbidity reduction as the most critical management priority for seagrass conservation. Keywords: seagrass, Halodule wrightii, coastal habitat, Bayelsa State, turbidity.