Coordinator: Michael P. Crosby (USA)

Co-Coordinator: Kiyoshi Yamazato (Japan)

　

　

Amakusa Marine Biological Laboratory Graduate School of Kyushu University Amakusa, Kumamoto, JAPAN

satoshi@mbox.ambl-unet.ocn.ne.jp

　

²Fisheries University of Tokyo Shinagawa, Tokyo, JAPAN

　

Sekisei Lagoon, situated between Ishigaki and Iriomote Is., contains the largest coral reef in Japan. In 1998, coral bleaching was recorded in Sekisei Lagoon, with the damage in northern half of the lagoon. In the summer of 1999 and 2000 seawater temperature in Sekisei Lagoon did not exceed 30℃ and no bleaching was recorded. In 2001, the seawater temperature reached 30°by the end of June and remained at this for longer than two months.

　

Coral bleaching was observed in August and a general survey of the bleaching was carried out at nine sites in the middle August. Most colonies of the genus Acropora were in the process of bleaching. The progress of the bleaching was followed by marking colonies of Acropora hyacinthus and A. selago. Most colonies, i.e., 70 - 98%, of both species were in the process of bleaching, but only 10% of the colonies of A. hyacinthus and 30% of A. selago were completely bleached. These marked colonies were observed again in November. All of the colonies completely bleached in August died while most of those colonies moderately bleached in August were in the process of recovery. Ten to twenty percent of A. hyacinthus and 44% of A. selago colonies were dead. The percentage of dead colonies was lower than that in 1998. However, these dead colonies could survive during the bleaching event in 1998. Taking this fact into consideration, the bleaching event in 2001 was not a negligible event.

　

　

Institute of Oceanography Nha Trang, VIETNAM

thuysinh@dng.vnn.vn

　

Coral reefs at Con Dao waters were impacted strong during bleaching event in 1 998. Data collected in October 1998 showed the frequency of bleached coral colonies occurred with the mean value of 37 percent. About 14% of the coral colonies were found to be dead at this time. The monitoring data (ReefCheck and LIT) every year after the event showed the variation of corals, coral reef fish and some macro-benthos. Hard corals recovered very differently among repeated sites. The general trend showed slow recovery in almost reefs. The average coverage of the reefs without impact of Lynda typhoon (Nov. 1997) was still lower than 30 percent. The situation had been a bit better since 2000. Recovery trend of soft corals had not observed. Their coverage on the reef dominant by soft corals before bleaching (more than 20%) was still maintained at low level (3-4%) through all studying years. The variation of coral reef fish density looked satisfactory. The total density of main fish families increased from 400 inds / 500sq.m in October 1998 to more than 600 in 2,000 and more than 1,000 in 2001. Main contribution of the trend belonged to Damselfish, butterfly fish and surgeonfish. The change of some macro benthos should be also paid attention. They were phenomena of sea urchin increase after Lynda typhoon (Nov. 1997) and than decrease after bleaching event in 1998, and the decline of giant clam (Tridacna crocea) density at some sites.

　

　

Hudson Marine Management Services Camden, New Jersey, USA

jerojam@bellsouth.net

　

Vessel groundings are a major source of adverse impact to coral reefs throughout the world. Whereas the vast majority of such incidents are unreported, there are numerous instances in which a Responsible Party funds both an investigation of coral injuries and appropriate restoration measures. In these cases, representatives of government regulatory agencies and the Responsible Party can work closely together to identify and implement procedures to evaluate damage and repair the coral reef.

　

Until recently, defining the spatial extent of and analyzing the characteristics of coral reef injuries caused by vessel hull impact was a daunting task. Traditional investigations by scientific divers used standard tape measurements with physical markers. However, the use of an Integrated Video Mapping System now allows Geographic Information System (GIS) technology to produce highly accurate mapping products that are linked to photodocumentation. This enables completely objective injury assessments to be quickly and reliably made.

　

Although much of the subjectivity previously associated with injury assessment has now been eliminated, there is seldom initial agreement between the parties on the extent to which coral reef structure and/or function can be restored. Why these differences in view occur is primarily attributable to practical rather than scientific considerations. The value of understanding the mindset of commercial interests such as shippers and insurers is examined and discussed.

　

　

Faculty of Science, University of the Ryukyus Nishihara, Okinawa, JAPAN

tsuchiya@sci.u-ryukyu.ac.jp

　

Since 1980, many coral bleaching events have been reported in Okinawa, Japan. The 1998 event was the most conspicuous one among them, and again an extensive bleaching occurred in many reefs in Okinawa in 2001. Various sized colonies of completely bleached Pocillopora damicornis were collected in order to study the effect of the coral bleaching on the structure of its associated community in different bleaching events. Although six species of the xanthid crab Trapezia were collected in each survey and it was comparable to the species richness on healthy colonies, bleached colonies harbored fewer individuals and species of obligate symbionts than unbleached ones, before the event. Colonies harboring no symbionts were also common. Heterosexual pairs of the symbionts such as Trapezia spp., the shrimp Alpheus lottini and the goby Paragobiodon spp. were rather uncommon and the abundance of ovigerous females of Trapezia was lower and their clutch size was smaller than usual in the 1998 event. However, Trapezia spp. associated with bleached corals was considered to mature at a smaller size and produced more eggs than crabs of the same size associated with healthy coral colonies in 1991. Apparently, coral bleaching affected the community structure or population traits of the symbionts in different ways. According to the repeated bleaching events, P. damicornis and its associated community have completely disappeared in some local reefs. The mass coral bleaching in 1998 issued a stern warning to possible global environmental changes.