[A-CG41] Coastal Ecosystems 2. Coral reefs, seagrass and macroalgal beds, and mangroves

[ACG41-03] Coral declines and fish community changes in the Kuroshio current region

*Masaaki Sato¹, Yohei Nakamura² (1.Fisheries Technology Institute Japan, Fisheries Research and Education Agency, 2.Kochi University)

Keywords:Coral bleaching, Coral reef fish, Climate change, Global warming

Over the last several decades, the world's oceans have warmed substantially, and frequency of storm and freshwater runoff have increased as a result of global climate change. These environmental disturbances have triggered the mass bleaching and degradation of corals in the Indo-Pacific region, including the Kuroshio Current region. The degradation of coral reefs can have negative effects on fishes that inhabit the reefs and their provisioning of ecosystem services. To assess the influence of coral degradation on the associated fish in this region, we compared fish communities on coral habitats in 2020-2022 with those in 2005-2010, when bleaching and degradation of coral were less intensive in this region. Using the same methods of Nakamura et al. (2008, 2013), underwater visual surveys were performed at the same seven sites in the Kuroshio current region of Japan: (1) Amitori and (2) Itona in Yaeyama Islands, (3) Bise in Okinawa Island, (4) Akaogi and (5) Akagina in Amami Oshima Island, and (6) Yokonami and (7) Kashiwajima in Shikoku Island. By 2020-2022, coral covers have largely declined at Amitori, Akagina and Yokonami sites due to different environmental disturbances including rising sea water temperatures in summer, increased freshwater runoff, or extreme cold events in winter. The underwater visual surveys found that fish community changed at these sites, which was likely to be associated with the decline of coral cover there. In the presentation, we would additionally discuss details of fish community changes by focusing on functional groups among different feeding habitats and ecosystem service provisions.