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标题：Physiological Response to Thermal Stress of the Caribbean Corals Orbicella annularis and Porites astreoides
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作者：Francisco Javier Soto-Santiago ; Alex Edgardo Mercado-Molina ; Koralis Reyes-Maldonado and Alberto Miguel Sabat 等
期刊名称：Research Journal of Environmental Sciences
印刷版ISSN：1819-3412
电子版ISSN：2152-8238
出版年度：2017
卷号：11
期号：2
页码：48-57
DOI：10.3923/rjes.2017.48.57
出版社：Academic Journals Inc., USA
摘要：Background and Objective: The physiological response of corals to ocean warming is an essential component of their overall resiliency to climate change . It is important to understand how increasing sea surface temperature will affect the mutualistic relationship between corals and their endosymbionts dinoflagellates ( Symbiodinium spp.). This study focused on the effects of temperature stress on the photophysiology of two Caribbean corals differing in life history strategies: Orbicella annularis ( O. annularis ) and Porites astreoides ( P. astreoides ). Materials and Methods: A total of 12 fragments of each species were collected from the Puerto Morelos, Mexico shoreline. Six fragments of each species were placed under ambient light and a water temperature of 28°C and the other six under ambient light and an elevated temperature of 32°C for 10 days. Maximum pressure over photosytem II (Qm) was estimated daily while chlorophyll content and Symbiodinium densities were measured at the end of the experiment. Results: Qm values were considerably higher in O. annularis at 32°C when compared to O. annularis at 28°C. In contrast, Qm values for P. astreoides did not differ significantly between treatments. Interestingly, Qm values of P. astreoides at 32°C was similar to that of O. annularis at 28°C. Orbicella annularis showed higher Symbiodinium densities and significantly higher concentrations of chlorophyll a at 28°C than at 32°C. In P. astreoides , no differences on chlorophyll content and Symbiodinium densities were found between temperature treatments. Porites astreoides showed higher chlorophyll a content and Symbiodinium densities than O. annularis under high temperature stress. Conclusion: Low Qm values but high chlorophyll concentrations and Symbiodinium densities within P. astreoides after induced temperature stress provides a physiological basis of the opportunistic strategy of this species. However, the significant increase in Qm, lower chlorophyll a concentration and reduced Symbiodinium densities observed in O. annularis at 32°C highlights its vulnerability to ocean warming. If O. annularis , which is considered one of the main builders of Caribbean coral reefs, disappears and is replaced by relatively small and weedy P. astreoides , the structural heterogeneity of Caribbean coral reefs will be reduced.