Japan Geoscience Union Meeting 2016

Presentation information


Symbol A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG15] Coastal Ecosystems - 2. Coral reefs, seagrass meadows, and mangroves

Tue. May 24, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Toshihiro Miyajima(Marine Biogeochemistry Group, Division of Ocean-Earth System Science, Atmosphere and Ocean Research Institute, The University of Tokyo), Atsushi Watanabe(Department of Mechanical and Environmental Informatics Graduate School of Information Science and Engineering Tokyo Institute of Technology), Yu Umezawa(Nagasaki University)

5:15 PM - 6:30 PM

[ACG15-P05] Relationship of Massive Coral Distribution with wave height, soil particle quantity and water depth in Amitori Bay, Iriomote Island, Japan

*Shinya Shimokawa1, Hiroyoshi Kohno2, Tomokazu Murakami1, Akira Mizutani2, Takumi Shibayama3, Yuiko Yamamoto2, Akiyuki Ukai4, Kouta Nakase4 (1.National Research Institute for Earth Science and Disaster Prevention, 2.Okinawa Regional Research Center, Tokai University, 3.Graduate School of Life and Environmental Sciences, Tsukuba University, 4.Environment Business Division, Civil Engineering Headquarters, Penta-Ocean Construction. Co. Ltd.)

Keywords:Massive coral, Wave height, Soil particle, Water depth, Iriomote Island, Amitori Bay

Amitori Bay is located in the northwest region of Iriomote Island, Japan with a few km length. The bay has no access roads, and the bay perimeter is uninhabited, thus, has various natural environments without human impact. In fact, broad areas of coral have developed in the bay, and their life forms, coverages, sizes, and species vary depending on their locations, thus, the bay is considered to be one of the most suitable areas for studying the relationship between coral distribution and physical variables.
We have investigated the relation between tabular and branching coral distribution and physical variables in Amitori Bay using coral distribution investigation, oceanic–atmospheric–riverine observations and numerical simulations using ocean and wave models [e.g., Shimokawa et al., 2014].
In this study, we focused massive coral which is one of representative coral life forms in Amitori Bay other than tabular and branching corals [Shimokawa et al., 2015]. Field observations were conducted to obtain data on coral distributions, sea temperature, sea salinity, wind speed, and river flow rate. Ocean and wave model numerical simulations and soil particle tracking analysis were conducted to obtain the spatial and temporal distributions of wave height and the numbers of soil particles with the observed data.
The conclusions were the following: (i) Massive coral coverage shows an inverse relation with water depth. (ii) Massive coral coverage shows an inverse relation with other coral coverage. (iii) Massive coral coverage shows a weak relation with wave height. (iv) Genus numbers and coverage of massive coral show an inverse and a direct relation with soil particle quantities, respectively. The relation in (iii) is attributable to the strong wave tolerance of massive corals because of their form and stiff skeleton, and to the slight difference of wave height between the east and west sides of the bay. The relation in (iv) results from the fact that coral genera except for Porites with strong ability of mucus removal are hard to survive on the east side with large quantities of soil particles, although various coral genera can inhabit in the west side with small quantities of soil particles.
Shimokawa S., T. Murakami, A. Ukai, H. Kohno, A. Mizutani and K. Nakase, 2014, Relationship between coral distributions and physical variables in Amitori Bay, Iriomote Island, Japan, J. Geophys. Res.: Oceans, 119, 8336-8356 (doi: 10.1002/2014JC010307).
Shimokawa, S., H. Kohno, T. Murakami, A. Mizutani, T. Shibayama, Y. Yamamoto, A. Ukai, and K. Nakase, 2015, Relationship Between Massive Coral Distribution and Physical Variables in Amitori Bay, Iriomote Island, Japan, J. Jpn. Soc. Civ..Eng. B3, 71, I_969-i_974 (in Japanese with English abstract).