<![CDATA[Abstract. Amores A, Aguilar SN, Maxey E. 2026. Abundance-diversity decoupling in tropical seagrass meadows of Mati City, Philippines. Nusantara Bioscience 18 (2): n180201. https://doi.org/10.13057/nusbiosci/n180201. Seagrass ecosystems provide important ecological functions but are increasingly exposed to environmental and human pressures. Understanding changes in these ecosystems requires assessment of both abundance and diversity over time. This study examined temporal variation in seagrass communities in two tropical meadows, Lawigan and Tamisan, in Mati City, Davao Oriental, Philippines, using quarterly sampling from March 2024 to December 2025. Seagrass shoots were quantified using transect-quadrat methods, and community structure was evaluated through diversity indices and individual-based rarefaction analyses. Eight seagrass species were recorded during the study period. Total shoot abundance increased by approximately 350%, from 2,098 individuals in 2024 to 9,443 in 2025, whereas pooled annual species richness increased only slightly from six to seven species. Despite higher abundance, diversity indices declined, indicating greater dominance by a few species. Species-level analyses showed marked increases in Enhalus acoroides and Cymodocea serrulata, while other species remained stable, declined, or occurred intermittently. Rarefaction analyses revealed similar expected richness among samples in 2024 but greater variability in 2025 under standardized sampling effort. The results show that increases in seagrass abundance do not necessarily correspond to increases in diversity. Instead, higher abundance was associated with greater species dominance and uneven community structure. These findings highlight the importance of combining abundance, diversity, and standardized richness measures in long-term monitoring to improve assessments of tropical seagrass ecosystem condition.]]>
