Plankton diversity in Raja Ampat: Foundation of the coral reef trophic structure

¹ Faculty of Fisheries and Marine Sciences, Bogor Agricultural University, Indonesia
² Research Center for Limnology. The Indonesian Institute of Science
³ Department of Applied Chemistry and Biochemistry, National Institute of Technology (KOSEN), Wakayama College, Gobo, Wakayama 644-0023, Japan
⁴ Advance School for Ecosystem Engineering, National Institute of Technology (KOSEN), Wakayama College, Gobo, Wakayama 644-0023, Japan
⁵ Institute for Community Innovation in Collaboration with KOSEN (MILLA), Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan
⁶ Wakayama Prefectural Museum of Natural History, Kainan, Wakayama 642-0001, Japan

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Raja Ampat, located within the Coral Triangle, features multiple management zones, including core, open access, and tourism areas. Planktons, as the base of the marine food web, play a vital role in sustaining coral reef ecosystems. Understanding their diversity is essential for evaluating ecosystem health and informing conservation efforts. This study aimed to assess plankton biodiversity in the coral reef ecosystem of Raja Ampat. Sampling was conducted in January 2018 across multiple sites from surface waters using a 23 μm mesh net. The samples were preserved in Lugol’s solution, quantified microscopically, and morphologically identified. Biodiversity indices were analyzed using the Shannon-Wiener index (H’), evenness (E), and dominance (C), whereas spatial patterns were examined using Bray-Curtis cluster analysis. In total, 11–21 phytoplankton taxa were recorded, including Cyanophyceae, Bacillariophyceae, Dinophyceae, and Chlorophyceae. Zooplankton consisted of 2–6 taxa from Protozoa, Crustacea, and Chaetognatha. Phytoplankton diversity was the highest in Arefi (H’ = 2.21) and the lowest in Paniki Besar. Cluster analysis identified three phytoplankton groups and two zooplankton groups. These findings highlight the spatial variation in plankton communities and emphasize their value as indicators of coral reef ecosystem structure and health in the Raja Ampat.