2006 Fiscal Year Final Research Report Summary
Resilience of coral communities under the global climate change: supply of coral larvae from Kerama Islands to Okinawa Island, and recovery of coral communities in Okinawa I
| Project/Area Number |
16310158
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Resource conservation science
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| Research Institution | University of the Ryukyus |
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Principal Investigator |
SAKAI Kazuhiko University of the Ryukyus, Sesoko Station, Tropical Biosphere Research Center, Associate Professor (50153838)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Hermatypic corals / Coral community / Coral bleaching / Coral recruitment / Okinawa Island and Kerama Islands / Reef connectivity / Acanthaster planci / Algae and corals |
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| Research Abstract |
1. Coral populations at Kerama Islands are shown to be larval sources for Okinawa Island in spawning corals from the field study; recruitment of spawning corals was greater on reefs in Okinawa I. where closer to Kerama Is. In contrast, very little larvae were supplied from Kerama Is. to Okinawa I. in brooding corals.
2. There was a large recruitment of spawning corals (mainly acroporids) in Okinawa I. after the mass coral bleaching in 1998, but most of the recruits did not survive on most reefs. Mortality duet to predation by the coral eating starfish, Acanthaster planci, was greatest of detected mortality factors. As a result, recovery of coral communities was very limited in terms of number of reefs in Okinawa I.; coral cover reached 30% at 10% of the study sites (n=18) in 2006.
3. Analysis of change in coral cover from long-term monitoring revealed that recovery potential of coral communities had been much declined around Sesoko I., which is located at northern part of Okinawa I., in the last 25 years.
4. Coral recruitment in Okinawa I. was drastically decreased by reduction of adult coral colonies at Kerama Is. due to predation by out-braking A. planci after 2002.
5. Dispersal distance of acroporid corals that have long planktonic period as larvae was suggested to be limited within 200 km from parent colonies.
6. Contact with macroalgae decreased growth rate and fecundity of Acropora corals. The corals with contact with macroalgae appear to consume their resource for repairing injury caused by the contact, remaining small amount of resource for growth and reproduction.
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[Journal Article] Eggs regulate sperm flagellar motility initiation, chemotaxis, and inhibition in the coral, Acropora digitifera, A. gemmifera, and A. tenuis.2006
Author(s)
Morita, M., Nishikawa, A, Nakajima, A., Iguchi, A., Sakai, K., Takemura, A., Okuno, M.
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Journal Title
The Journal of Experimental Biology 209
Pages: 4574-4579
Description
「研究成果報告書概要(欧文)」より
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