Seasonal fluctuation in zooxanthellar genotype composition and photophysiology in the corals Pavona divaricata and P. decussata
Seasonal fluctuation in zooxanthellar genotype composition and photophysiology in the corals Pavona divaricata and P. decussata
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Pavona divaricata 和 P. decussata 珊瑚虫黄藻基因型组成和光生理学的季节性波动
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发表时间：
2008
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影响因子：
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通讯作者：
M. Hidaka
中科院分区：
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作者：
R. Suwa;M. Hirose;M. Hidaka
我们同时研究了日本冲绳高纬度地区同域分布珊瑚Pavona divari-cata和P. decussata的最大量子产额（Fv/Fm）、细胞密度和虫黄藻基因型分支组成的季节性波动。两种藻对光照和海水温度的季节变化有不同的反应。在所有采样时间，叉枝银汉草仅与分支C虫黄藻相关，而叉枝银汉草的基因型分支组成波动。其中3个群体全年都含有D分支，其他7个群体的分支类型从C变为D或反之亦然，或者在某些采样场合含有两个分支的混合物。尽管两种珊瑚在实验期间均未发生漂白，但在冷、暖海条件下，含有C分支的叉枝叉枝珊瑚和叉枝叉枝珊瑚的Fv/Fm值均有所下降，而含有D分支的叉枝叉枝珊瑚的Fv/Fm值则保持稳定。在低温和高温条件下，D分支的叉枝青冈比C分支的叉枝青冈受到的伤害小，光系统II的恢复快。这些结果表明，同域同源珊瑚有不同的共生体转换灵活性，这种差异可能会解释观察到的差异，应力敏感性之间的两个物种。在高纬度珊瑚礁中，冬季低温和夏季高温都可能是导致珊瑚白化的潜在压力源，至少在具有高进化枝C虫黄藻保真度的珊瑚中是如此。
We simultaneously examined seasonal fluctuations in maximum quantum yield (Fv/Fm), cell density and genotypic clade composition of zooxanthellae in the sympatric corals Pavona divari- cata and P. decussata at a high latitude site in Okinawa, Japan. The 2 species had different responses to seasonal changes in light and seawater temperature. P. decussata was associated only with clade C zooxanthellae (at all sampling times) while genotypic clade composition fluctuated in P. divaricata. Three colonies of P. divaricata harbored clade D throughout the year and the other 7 colonies changed clade type from C to D or vice versa, or contained a mixture of both clades on some sampling occasions. Though neither coral species suffered bleaching during the experimental period, there were Fv/Fm decreases in P. decussata and P. divaricata harboring clade C during cold and warm sea- sons; Fv/Fm of P. divaricata harboring clade D was stable. When exposed to low or high temperature under normal or high light, P. divaricata harboring clade D was less damaged and Photosystem II recovery was faster than in P. decussata harboring clade C. These results suggest that the sympatric congeneric corals have different symbiont switching flexibilities and this difference might account for the observed difference in stress susceptibility between the two species. In high-latitude reefs, both winter low temperatures and summer high temperatures may be potential stressors that cause coral bleaching, at least in corals with high clade C zooxanthellar fidelity.