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Denis V.,Academia Sinica, Taiwan | Loubeyres M.,Academia Sinica, Taiwan | Doo S.S.,Academia Sinica, Taiwan | Doo S.S.,University of Sydney | And 5 more authors.
Coral Reefs | Year: 2014

The resilience of coral reefs relies significantly on the ability of corals to recover successfully in algal-dominated environments. Larval settlement is a critical but highly vulnerable stage in the early life history of corals. In this study, we analyzed how the presence of two upright fleshy algae, Sargassum mcclurei (SM) and Padina australis (PA), and one crustose coralline algae, Mesophyllum simulans (MS), affects the settlement of Acropora muricata larvae. Coral larvae were exposed to seawater flowing over these algae at two concentrations. Larval settlement and mortality were assessed daily through four variables related to their behavior: swimming, substratum testing, metamorphosis, and stresses. Temperature, dissolved oxygen, pH, algal growth, and photosynthetic efficiency were monitored throughout the experiment. Results showed that A. muricata larvae can settle successfully in the absence of external stimuli (63 ± 6 % of the larvae settled in control treatments). While algae such as MS may stimulate substrate testing and settlement of larvae in the first day after competency, they ultimately had a lower settlement rate than controls. Fleshy algae such as PA, and in a lesser measure SM, induced more metamorphosis than controls and seemed to eventually stimulate settlement. A diverse combination of signals and/or modifications of microenvironments by algae and their associated microbial communities may explain the pattern observed in coral settlement. Overall, this study contributes significantly to the knowledge of the interaction between coral and algae, which is critical for the resilience of the reefs. © 2014 Springer-Verlag Berlin Heidelberg.

Wen C.K.C.,James Cook University | Chen K.-S.,Taiwanese Fisheries Research Institute | Hsieh H.J.,Penghu Marine Biological Research Center | Hsu C.-M.,National Taiwan University | And 3 more authors.
Marine Pollution Bulletin | Year: 2013

Breakwaters are widely used in coastal development. Breakwaters can alter habitats by undermining shallow coastal ecosystems, especially coral reefs. However, recent studies indicate that mature breakwaters can have well-developed corals and coral-associated fishes. Breakwaters with colonized corals may act as surrogates of natural coral reefs against the global coral crisis. Here, we examined the composition of corals, fishes, and benthic biota/abiota between natural reefs and mature breakwaters to evaluate the possibility of breakwaters supplementing natural reefs. We found equal or higher coral cover, fish abundance, and species richness on breakwaters. Conversely, differential coral growth forms and fish assemblages on mature breakwaters suggested the irreplaceability of natural reefs. Corals and coral reef fishes on mature man-made structures, however, may improve the resistance and resilience of coral reefs. Conclusively, despite high coral cover on mature man-made structures appropriate management (e.g., marine reserves) is still necessary to sustain the coral reefs. © 2013 Elsevier Ltd.

Fontana S.,Academia Sinica, Taiwan | Keshavmurthy S.,Academia Sinica, Taiwan | Hsieh H.J.,Penghu Marine Biological Research Center | Denis V.,Academia Sinica, Taiwan | And 9 more authors.
PLoS ONE | Year: 2012

A novel symbiosis between scleractinians and hydroids (Zanclea spp.) was recently discovered using taxonomic approaches for hydroid species identification. In this study, we address the question whether this is a species-specific symbiosis or a cosmopolitan association between Zanclea and its coral hosts. Three molecular markers, including mitochondrial 16S and nuclear 28S ribosomal genes, and internal transcribed spacer (ITS), were utilized to examine the existence of Zanclea species from 14 Acropora species and 4 other Acroporidae genera including 142 coral samples collected from reefs in Kenting and the Penghu Islands, Taiwan, Togian Island, Indonesia, and Osprey Reef and Orpheus Island on the Great Barrier Reef, Australia. Molecular phylogenetic analyses of the 16S and 28S genes showed that Acropora-associated Zanclea was monophyletic, but the genus Zanclea was not. Analysis of the ITS, and 16S and 28S genes showed either identical or extremely low genetic diversity (with mean pairwise distances of 0.009 and 0.006 base substitutions per site for the 16S and 28S genes, respectively) among Zanclea spp. collected from diverse Acropora hosts in different geographic locations, suggesting that a cosmopolitan and probably genus-specific association occurs between Zanclea hydroids and their coral hosts. © 2012 Fontana et al.

Keshavmurthy S.,Academia Sinica, Taiwan | Hsu C.-M.,Academia Sinica, Taiwan | Hsu C.-M.,National Taiwan University | Kuo C.-Y.,Academia Sinica, Taiwan | And 11 more authors.
Zoological Studies | Year: 2012

Galaxea fascicularis possesses a unique sexual pattern, namely "pseudo-gynodioecy", among scleractinian corals. Galaxea fascicularis populations on the Great Barrier Reef, Australia are composed of female colonies that produce red eggs and hermaphroditic colonies that produce sperm and white eggs. However, white eggs of hermaphroditic colonies are incapable of being fertilized or undergoing embryogenesis. In this study, the reproductive ecology and fertilization of G. fascicularis were examined in Chinwan Inner Bay, Penghu, Taiwan in Apr.-June 2011 to determine the geographic variation of sexual patterns in G. fascicularis. Synchronous spawning of female and hermaphroditic colonies was observed between 17:30 and 20:00 (1 h after sunset) between 24-28 May 2011 (7-11 nights after the full moon in May), and at same times between 22-24 June 2011 (6-8 nights after the full moon in June). Red eggs were significantly larger than white eggs, although both types of eggs had a distinct nucleus, which was located at the edge of the eggs, suggesting that they were in the final stage of maturation and ready to release gametes. Crossing experiments showed that both white and red eggs could be fertilized in vivo, and they synchronously developed into swimming larvae, suggesting that instead of being pseudo-gynodioecious, the sexual pattern of G. fascicularis is gynodioecious.

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