COS 185-4 - CANCELLED - The Influence of Marine Protected Areas, Reef Habitat, and Human Population on Changes in Fish Diversity in the Center of Marine Diversity

Abstract: The Visayas Region of the Philippines is a global epicenter of marine fish biodiversity. Hypotheses attribute this peak of species richness within the Coral Triangle to processes that occur at geological time scales. However, changes in biodiversity may occur on ecological time scales, allowing for the assessment of the potential impact of anthropogenic activities. Low species richness in the Visayas Region has previously been associated with stressors such as habitat degradation, overfishing, and harvesting individuals for the aquarium trade. Many marine protected areas (MPAs) have been established throughout the Philippines to mitigate the cumulative negative effect of these stressors. While most of the country’s MPAs lie within the Visayas Region, this region has been termed the “epicenter of conservation adversity” within the Philippines. This study examines the effect of MPAs, reef habitat, and human population on changes in fish diversity in the Visayas Region between surveys conducted in the 1970s, 2010s, and 2020s. Individual- and sample-based species accumulation and rarefaction curves were used to create snapshots of species diversity from these distinct periods. Site-specific species richness and MPA indices (distance, size, age) were compared to determine the effect of MPAs on fish diversity. Preliminary results indicate that species richness decreased between the 1970s and 2010s then increased in the 2020s, potentially indicating a release from fishing pressure due to the COVID-19 pandemic. Furthermore, there is a significant relationship between MPAs and species richness suggesting that species richness has increased over time with proximity to MPAs, potentially indicative of the spillover effect from effective MPA management. However, there is a counterintuitive effect where MPA influence negatively impacts sites in the 1970s. This highlights the importance of incorporating other potential covariates like reef habitat and human population. In conclusion, this study suggests an effect of era and MPA indices on species richness over four decades in the center of marine fish diversity.