Waterbird beta-diversity responses to disturbance in afrotropical wetlands: Implications for conservation policy and sustainability

Gaining insights into how disturbance shapes biodiversity patterns and overall ecosystem functioning is fundamental for guiding meaningful conservation and policy-driven sustainability strategies in rapidly transforming tropical wetlands. Our research evaluated the extent to which anthropogenic disturbance influences waterbird beta-diversity (β-diversity) and indicator species across 29 Afrotropical wetlands in the Niger delta region of Nigeria. We delineated our wetlands into lowly and highly disturbed classes using a constrained ordination technique, while waterbird presence-absence dataset sampled between 2019 and 2021 were analyzed to partition total β-diversity into its components of turnover (species replacement) and nestedness-resultant dissimilarity associated with richness differences. We used PERMDISP, PERMANOVA, and Welch's t -test to evaluate spatial variations and compositional differences between our disturbance classes. To identify specific taxa associated with each anthropogenic disturbance class, we employed the indicator species analysis technique. The compositional dissimilarity between lowly and highly disturbed classes was primarily driven by the turnover component of β-diversity, with nestedness contributing comparatively little. Nestedness richness difference was greater in lowly-disturbed wetlands, whereas the highly-disturbed wetlands - characterized by high richness difference – exhibited low nested patterns or high species turnover, which is indicative of species filtering. Our indicator species analyses identified four waterbird taxa associated with anthropogenic disturbance extents, with three indicative of highly disturbed wetlands and one indicative of lowly disturbed wetlands. Our results indicate that increase in disturbance shifts waterbird assemblages toward disturbance-tolerant species, leading to lower ecological heterogeneity and potentially limiting wetland recovery and resilience over time, since these species acts as vital ecosystem engineers. Overall, our findings advance wetland conservation policy and environmental sustainability, highlighting the urgent need to reduce disturbance, improve habitat protection strategies, as well as incorporating indicator species into adaptive monitoring frameworks as meaningful mechanisms for long-term ecological sustainability in Afrotropical systems.