Connectivity between mesophotic coral communities from different depths affected by water transparencies

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K07237
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Conservation of biological resources
• Research Institution: University of the Ryukyus
• Principal Investigator: Naruse Tohru 琉球大学, 熱帯生物圏研究センター, 准教授 (30398309)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 中深度サンゴ

Outline of Final Research Achievements

Mesophotic corals and their habitat were surveyed at Funaura Bay, Iriomote Island. Leptoseris species were observed at relatively shallower zone (20-25m) at the closed-off section of the bay, whereas they were found at much deeper zone (below 30m) near the entrance of the bay. There were marked differences in the illumination intensity at the depth of 20m; only 49.1% of the illumination intensity was recorded at the closed-off section of the bay when compared with that of the entrance of the bay. These results support the hypothesis that “the depths of mesophotic coral habitats become shallower where the transparencies of the water are lower”. Another hypothesis “communities at deeper zone with high transparencies are genetically connected with communities at shallower zone with low transparencies” is still under testing, but there are at least differences in species compositions between the two extreme communities.

Free Research Field

動物分類学

Academic Significance and Societal Importance of the Research Achievements

現在行われているサンゴ礁の研究や保全の取り組みのほとんどは、上部浅海帯のサンゴ礁のみを対象としている。中深度サンゴ礁には、サンゴ類のみならず、藻類やメガベントスやマクロベントス、ネクトンなど、非常に多くの生物を育むであろうことが考えられる。また、上部浅海帯のサンゴ礁生態系の文字通り基礎となっている中深度サンゴ礁についての知見を蓄積する事は、熱帯・亜熱帯島嶼の生態系研究や保全を行うにおいて必要不可欠である。本研究では、両者の接続性についても検証したが、湾奥と湾口では種構成が異なる事もわかってきたため、それぞれが保全対象のユニットとして捉えられるべきであることが浮き彫りになってきた。