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A study of larval settlement of the coral, Pocillopora damicornis in Singapore
Author
Lee, Co Sin
Supervisor
Goh, Beverly
Walford, Juan
Abstract
A comprehensive study of coral larval settlement behavior and settlement cues was conducted on the brooder spawning scleractinian coral Pocillopora damicornis in aquaria conditions, including (1) effects of stocking density, (2) settlement preferences, (3) substrate conditioning and (4) coral-algal interactions. Spawning of P. damicornis follows a lunar cycle and they release larvae just after the new moon. Larval settlement behaviour depended on lighting conditions and larvae had a tendency to settle under dark conditions. Larvae of P. damicornis had the highest rates of settlement within 3 days after the start of the experiment. There were no significant differences in settlement rates between the 3 stocking densities tested. The settlement preference experiment showed that the settlement rate of larvae of P. damicornis on 10%CR tiles (cement tiles containing 10% of coral rubble) was significantly greater than other substrates offered. The duration of tile conditioning did not have a significant effect on the settlement of P. damicornis larvae. However, the settlement rate of P. damicornis decreased when duration of conditioning increased from 1 to 8 weeks and clean, unconditioned tiles had a higher settlement rate.
The presence of macroalgae Bryopsis corymbosa, Halimeda opuntia and Sargassum sp. 1 inhibited larval settlement in P. damicornis, whereas Padina minor did not affect settlement. The coral-algal interaction study suggested that the mechanisms of coral/algae competition depend on physical, chemical and/or biological properties of the algae. A comparative study showed that larvae are more likely to settle on clean, unconditioned 10%CR tiles than on tiles covered with calcareous coralline algae (CCA). Post-settlement survivorship and the growth rate of the larvae which settled on clean, unconditioned 10%CR tiles were significantly higher than on CCA-covered tiles. The 10% CR tiles provided the best substrate for achieving a high rate of coral settlement. Overall, this study suggested that physical, chemical and/or biological cues are important in the process of coral settlement, and the results of the study can be applied in the management of coral reef ecosystems.
The presence of macroalgae Bryopsis corymbosa, Halimeda opuntia and Sargassum sp. 1 inhibited larval settlement in P. damicornis, whereas Padina minor did not affect settlement. The coral-algal interaction study suggested that the mechanisms of coral/algae competition depend on physical, chemical and/or biological properties of the algae. A comparative study showed that larvae are more likely to settle on clean, unconditioned 10%CR tiles than on tiles covered with calcareous coralline algae (CCA). Post-settlement survivorship and the growth rate of the larvae which settled on clean, unconditioned 10%CR tiles were significantly higher than on CCA-covered tiles. The 10% CR tiles provided the best substrate for achieving a high rate of coral settlement. Overall, this study suggested that physical, chemical and/or biological cues are important in the process of coral settlement, and the results of the study can be applied in the management of coral reef ecosystems.
Date Issued
2007
Call Number
QL377.C7 Lee
Date Submitted
2007