<![CDATA[Abstract. Kase AGO, Ginzel FI, Merryanto Y, Bessie DM, Tisera WL, Ngginak J, Kase AAB, Salvador M. 2026. Diversity, distribution, and environmental conditions of Caulerpa spp. in an eastern Indonesian intertidal zone. Biodiversitas 27 (9): d270908. https://doi.org/10.13057/biodiv/d270908. Caulerpa is a green macroalgal genus widely distributed in tropical coastal ecosystems and plays important ecological roles in shallow marine habitats. However, information on its distribution patterns and diversity in eastern Indonesian intertidal ecosystems remains limited. This study aimed to analyze the distribution patterns, diversity, and environmental conditions of Caulerpa spp. in the intertidal zone of Tablolong Beach, Kupang District, East Nusa Tenggara, Indonesia. Field sampling was conducted from August to September 2023 using transect-quadrat methods across four sampling sites. Morphological identification was based on thallus characteristics, while spatial distribution patterns and species diversity were analyzed using the Morisita index (Id) and Shannon-Wiener diversity index (H’). Environmental parameters including temperature, salinity, pH, and dissolved oxygen were also measured. Three species were identified, namely Caulerpa racemosa, Caulerpa lentillifera, and Caulerpa sertularioides, occurring predominantly in sandy intertidal habitats with varying degrees of seagrass association. All species exhibited clustered distribution patterns (Id>1), indicating aggregation within specific microhabitats. The Shannon-Wiener diversity index (H′<1) indicated low diversity across all sampling sites. C. lentillifera showed the highest mean percentage composition among the observed species. These findings suggest that localized habitat characteristics and environmental context may contribute to observed variation in spatial distribution and species composition of Caulerpa in tropical intertidal ecosystems. This study provides baseline ecological data for understanding Caulerpa communities and may support biodiversity conservation and sustainable coastal management in eastern Indonesia.]]>
