Aretz et al_2011.pdf - ORBi - Université de Liège

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Kölner Forum Geol. Paläont., 19 (2011)
M. ARETZ, S. DELCULÉE, J. DENAYER & E. POTY (Eds.)
Abstracts, 11th Symposium on Fossil Cnidaria and Sponges, Liège, August 19-29, 2011
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Modes of asexual reproduction and colony formation of zooxanthellate
scleractinian Oulastrea crispata
Satomi UEDA & Yoichi EZAKI
Department of Geosciences, Faculty of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku,
Osaka 558-8585, Japan; ueda@sci.osaka-cu.ac.jp; ezaki@sci.osaka-cu.ac.jp
Oulastrea crispata is a zooxanthellate, colonial scleractinian that is broadly distributed in the western
parts of the Pacific Ocean. The species inhabits specific environments, very shallow areas with turbid
conditions. O. crispata is very resistant to low-temperature and temporary drying conditions. Its pigmented
skeletons are very characteristic. The samples for this study were collected at a tide pool at the Hidaka area,
Wakayama Prefecture, in southwest Japan.
O. crispata exhibits sub-cerioid to plocoid colonial forms, and a mixed structural organization, even
within one colony, and is characterized by having both intratentacular and extratentacular budding (LAM
2000). Additionally, seasonal environmental fluctuations greatly influence corallite skeletogenesis and
growth form (CHEN et al. 2011), as well as mode of asexual budding. Individual corallite outlines vary
between peripheral and central parts of the same colony. In addition, modes of asexual reproduction and
its frequency also differ. Even if most individuals are covered and killed by calcareous algae, a few
individuals survive as patches. Soon after environmental recovery, the remaining survivors give rise to
offsets asexually so rapid as to spread over the whole corallum surface. The surviving individuals tend to
be limited to the central parts of the colony. Interestingly, there also is known to be a difference in the
frequency of egg production occurring in the colonial coral Goniastrea aspera (SAKAI 1998). According to
differences in position, a division of reproductive role contributes to nearly the whole growth of the colony.
O .crispata transforms its structural organization from cerioid to plocoid by appropriately selecting more
efficient modes of asexual reproduction.
O. crispata thus has an efficient reproductive strategy, according to subtle differences in position and
resultant ambient environments, and exhibits very high tolerance of environmental fluctuations by the
means of modifying their manner of colony formation and growth form.
CHEN, K.S., HSIEH, H.J., KESHAVMURTHY, S., LEUNG, J.K.L., LIEN, I.T., NAKANO, Y., PLATHONG, S., HUANG, H. & CHEN, C.A.
(2011): Latitudinal gradient of morphological variations in Zebra coral Oulastrea crispata (Scleractinia: Faviidae) in
the West Pacific. - Zoological Studies, 50 (1): 43-52
LAM, K.Y. (2000): Early growth of a pioneer recruited coral Oulastrea crispata (Scleractinia, Faviidae) on PFA-concrete
blocks in a marine park in Hong Kong, China. - Marine Ecology Progress Series, 205: 113-121
SAKAI, K. (1998): Effect of colony size, polyp size, and budding mode on egg production in a colonial coral. – Biological
Bulletin, 195: 319-325
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