Coral bleaching and reef micro-environments related to coral reef micro-topography

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K03997
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: Kumamoto University
• Principal Investigator: Matsuda Hiroki 熊本大学, 大学院先端科学研究部(理), 教授 (80274687)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: サンゴ礁 / 白化現象 / 喜界島 / 礁微地形

Outline of Final Research Achievements

In recent years, the coral bleaching has frequently occurred due to global warming, and in 2016, coral bleaching was confirmed on Kikai-jima, Kagoshima Prefecture, which is near the northern limit of coral reefs in the Ryukyu Islands. In this study, we focused on the microtopography of reefs on Kikai-jima and investigated the relationship between changes in sea surface temperature (SST) and meteorology and sea conditions.
Under standard summer meteorological conditions, regular changes in the SST corresponding to air temperature are shown regardless of the reef topography. On the other hand, when the wind direction is different from the prevailing wind in summer or when the wind is strong, SST tends to change at the point of open reef topography. This is considered that the warm surface seawater is blown out and low temperature seawater in the lower layer flows in. On the other hand, precipitation does not significantly affect SST.

Free Research Field

炭酸塩堆積学

Academic Significance and Societal Importance of the Research Achievements

造礁サンゴの白化現象は地球温暖化による汎世界的な海洋環境の変化や高海水温の頻発が重要であるが，個々のサンゴ礁域における海水温変化には，閉鎖的か開放的かなどの礁微地形や島内位置の違いによる風の影響が大きいことが明らかになった．このことは，海岸部におけるリゾート開発や港湾整備にあたっては，高海水温化の抑制に有効な風向・風速を把握し，それを阻害するような高層構造物の建設は避けるべきと言えよう．また礁内での海水循環に影響を与える防波堤整備や航路開鑿にも十分配慮すべきと考えられる．