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Tsuyoshi Suzuki 1 and Kazuki Kato 1 and Emi Makihara 1 and Takafumi Kobayashi 1 and Hitoshi Kono 1 and Kei Sawai 1 and Kuniaki Kawabata 2 and Fumiaki Takemura 3 and Naoko Isomura 3 and Hideyuki Yamashiro 4
Academic Editor:Floriano De Rango
1, Tokyo Denki University, 5 Senju-Asahi-Cho, Adachi-Ku, Tokyo 120-8551, Japan
2, RIKEN, 2-1 Hirosawa, Wako-Shi, Saitama 351-0198, Japan
3, Okinawa National College of Technology, 905 Henoko, Nago-Shi, Okinawa 905-2192, Japan
4, Sesoko Station, Ryukyu University, 3422 Sesoko, Motobu, Okinawa 905-0227, Japan
Received 16 August 2013; Revised 26 January 2014; Accepted 4 February 2014; 9 April 2014
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Coral reefs are a very important environment that maintains a great variety of life forms and also have important functions (e.g., an island formation and a tsunami prevention) for humans. However, by a coral bleaching on a massive scale caused by the impact of environmental change such as rapid rising of seawater temperatures and feeding damage by Acanthaster , there have been growing urgent and crucial concerns about the extinction of coral in recent years. The International Union for Conservation of Nature and Natural Resources has reported that a one-third overall of hermatypic corals are endangered species [1]. The coral reef ecological system that is easy to be affected by the environmental change is regarded as important as a biological indicator. Hence, conservation of coral reefs is attracting attention globally [2]. In Japan, the plans and studies such as Conserve Coral Reef Ecosystem [3] and Coral Reef Science [4] are proceeding. A preservation of coral reefs based on an analysis of an influence that an environmental condition change impacts the coral ecosystem becomes urgent need.
In the present situation, in order to preserve coral reefs, experts such as divers and researchers have been collecting data periodically on environmental conditions. However, these monitoring tasks are hampered by critical problems such as diving time limitations, decompression sickness, and accidents due to the hazardous environment. Therefore, we are developing an underwater monitoring system applying wireless sensor network technologies to support the monitoring tasks aimed at preserving the...