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Reproductive biology of scleractinian corals at Rottnest Island, Western Australia

Crane, Kevin (1999) Reproductive biology of scleractinian corals at Rottnest Island, Western Australia. Honours thesis, Murdoch University.

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The reproductive biology of selected scleractinian coral species was studied at Rottnest Island. At least 11 of the 25 coral species recorded at Rottnest Island were found to be reproductively active despite most species being at the southern limit of their latitudinal distribution.

In contrast to other tropical reefs in Western Australia and the Great Barrier Reef, spawning at Rottnest Island was not synchronous between coral species. Corals at Rottnest Island spawned during late summer I early autumn (January - May) after both full and new moon periods. This breakdown in synchrony probably occurs because these species are living at the latitudinal limits of their distribution.

Spawning was also not synchronous within four species with spawning occurring over one or more months. This provides further evidence that gamete release is generally not restricted to one short, discreet period.

Spawning occurred in the same general time frame as other corals from north western Australia, despite differences in seasonal temperature patterns. This provides further evidence that temperature does not operate as a simple direct proximate cue, to synchronise the various stages of gametogenesis.

A strong correlation between spawning and neap tides was not observed. Microtidal conditions at Rottnest Island may have not exerted enough selective pressure to shift spawning away from the inherited lunar rhythm.

Only a low level of coral recruitment (mean=l.44 recruits per tile pair) was detected in 1998 and these were exclusively from the Pocilloporidae. No recruitment of broadcast spawning corals occurred in 1998. If this were the norm for Rottnest Island, then these populations would have a reduced capacity to recover from damage.

Item Type: Thesis (Honours)
Murdoch Affiliation: School of Biological Sciences and Biotechnology
Notes: Note to the author: If you would like to make your thesis openly available on Murdoch University Library's Research Repository, please contact: Thank you.
Supervisor(s): Borowitzka, Michael and Simpson, Chris
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