Fish community diversity and conservation status in coral reef and seagrass ecosystems of Teluk Singkama coastal village, East Kalimantan, Indonesia

Abstract

The coastal waters of Teluk Singkama village, Sangatta Selatan District, East Kalimantan, encompassing seagrass meadows at Pantai Pasir Putih and coral reefs at Teluk Kaba, represent ecologically significant habitats that sustain diverse fish assemblages and support local livelihoods. The objective of this study was to analyze fish diversity and conservation status in these two ecosystems, thereby providing baseline information for sustainable management. Fish sampling was conducted in February 2025 using a traditional stationary fishing gear known as a set net (“sero”), with purposive sampling locations selected based on ecological considerations and expected migration routes of fish, and standardized collections performed every two days. A total of 176 individuals from 37 species, 20 families, and 5 orders were recorded in coral reefs, while 299 individuals from 23 species, 19 families, and 8 orders were documented in seagrass beds. Shannon-Wiener diversity indices revealed moderate diversity in both ecosystems, with coral reefs exhibiting higher diversity (H’ = 2.95) compared to seagrass beds (H’ = 2.44). Sørensen similarity analysis indicated 51.17% overlap between habitats, reflecting ecological connectivity while maintaining distinct assemblage structures. Conservation assessment based on the IUCN Red List categorized 40 species as Least Concern (LC), two species as Data Deficient (DD), and eight species as unlisted, suggesting relatively low immediate extinction risks but highlighting gaps in conservation knowledge. Ecologically, the findings emphasize the complementary roles of seagrass and coral reef ecosystems, with seagrass supporting higher abundance and coral reefs sustaining greater taxonomic richness, underscoring the necessity of conserving both habitats as interconnected units. Socio-economically, the exploitation of 23 species for local consumption and trade demonstrates strong community reliance on coastal biodiversity, necessitating continuous monitoring and adaptive management. Importantly, these results provide a critical baseline for sustainable coastal resource management in East Kalimantan, ensuring that biodiversity conservation and community livelihoods can be balanced in long-term planning.