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1 Department of Biology, California State University, 18111 Nordhoff Street, Northridge, California 91330-8303
2 National Museum of Marine Biology and Aquarium, 2 Houwan Road, Checheng, Pingtung 944, Taiwan, ROC
3 Institute of Marine Biodiversity and Evolution, National Dong Hwa University, 2 Houwan Road, Checheng, Pingtung 944, Taiwan, ROC
* To whom correspondence should be addressed. E-mail: tyfan{at}nmmba.gov.tw
To better understand the consequences of climate change for scleractinian corals, Stylophora pistillata was used to test the effects of temperature on the settlement and physiology of coral larvae. Freshly released larvae were exposed to temperatures of 23 °C, 25 °C (ambient), and 29 °C at light intensities of
150 µmol photons m–2 s–1. The effects were assessed after 12 h as settlement to various substrata (including a choice between crustose coralline algae [CCA] and limestone) and as maximum quantum yield of PSII (Fv/Fm) in the larvae versus in their parents. Regardless of temperature, 50%–73% of the larvae metamorphosed onto the plastic of the incubation trays or in a few cases were drifting in the water, and 14% settled on limestone. However, elevated temperature (29 °C) reduced the percentage of larvae swimming by 81%, and increased the percentage choosing CCA nearly 7-fold, both relative to the outcomes at 23 °C. Because temperature did not affect settlement on limestone or plastic, increased settlement on CCA reflected temperature-mediated choices by larvae that otherwise would have remained swimming. Interestingly, Fv/Fm was unaffected by temperature, but it was 4% lower in the larvae than in the parents. These results are important because they show that temperature can affect the settlement of coral larvae and because they reveal photophysiological differences between life stages that might provide insights into the events associated with larval development.
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