西沙永乐环礁造礁石珊瑚共生体对低光环境的生理响应  

Physiological responses to light limitation of reef-building corals in the Yongle Atoll of the Xisha Islands

作　　者：王永智 许莉佳 黄柏强 杨天件 綦世斌 陈辉 杨静 WANG Yongzhi;XU Lijia;HUANG Baiqiang;YANG Tianjian;QI Shibin;CHEN Hui;YANG Jing(South China Institute of Environmental Sciences,Ministry of Ecology and Environment,Guangzhou 510535,China;Guangdong Provincial Academy of Environmental Science,Guangzhou 510045,China)

机构地区：[1]生态环境部华南环境科学研究所,广东广州510535 [2]广东省环境科学研究院,广东广州510045

出　　处：《热带海洋学报》2024年第3期31-39,共9页Journal of Tropical Oceanography

基　　金：国家自然科学基金项目(42277362、41806139);广州市科技计划项目(202002030345);中央级公益性科研院所基本科研业务专项(PM-zx703-202105-176、PM-zx703-202004-143)。

摘　　要：光照是影响造礁石珊瑚生长与分布的重要因素之一,但目前关于造礁石珊瑚对低光环境的响应特征与适应性尚不清楚。本研究以西沙常见的疣状杯形珊瑚(Pocillopora verrucosa)、澄黄滨珊瑚(Porites lutea)和翘齿盘星珊瑚(Dipsastraea matthaii)为研究对象,于2021年春季在永乐环礁10m水深处开展了为期1周的原位遮光实验,其中遮光实验组与正常对照组相比光强削减了80%~90%,其日间有效光辐射(photosynthetically active radiation,PAR)为20.2~41.5μmol photons·m^(−2)·s^(−1)。实验结果显示,弱光状态下疣状杯形珊瑚、澄黄滨珊瑚和翘齿盘星珊瑚的实际光量子产量(ΦPSII)明显升高,最大电子传递速率(r-ETR_(max))和饱和辐射光强(Ek)出现了下降的现象,同时三种珊瑚的共生藻密度(翘齿盘星珊瑚除外)、叶绿素a含量、组织生物量和组织厚度出现了不同程度的下降,其中以澄黄滨珊瑚的变化最为显著,其共生藻密度下降了14.2%,组织生物量下降了32.9%。短期弱光限制中,造礁石珊瑚能够通过提高自身的实际光合效率或(和)降低虫黄藻密度适应光强的不足,但珊瑚共生体通过光合作用转化的能量短期内无法满足珊瑚宿主自身正常生长的代谢需求,因而出现消耗大于获得、珊瑚组织生物量和组织厚度短暂下降的情况。Light is one of the most important factors influencing the growth and distribution of reef corals,but the physiological response and adaptability of reef corals to low light is not well understood.In this study,we used an in-situ shading experiment with three typical coral species(Pocillopora verrucosa,Porites lutea and Dipsastraea matthaii)to test how physiological response of corals under light limitation.The experiment site is located at the depth of 10 meters of the Yongle atoll,in which the irradiance in the shaded area was reduced by 80%~90%,and the photosynthetically active radiation(PAR)ranges from 20.2μmol photons·m^(-2)·s^(-1) to 41.5μmol photons·m^(-2)·s^(-1).The results showed that the physiological parameters of three corals changed significantly under light limitation.During 7-day experiments,the effective photosynthetic efficiency(ΦPSII)of the three corals increased,while the maximum electron transport rate(r-ETRmax)and the minimum saturating irradiance(Ek)decreased significantly.Meanwhile,the zooxanthellae density(except Dipsastraea matthaii),chlorophyll a content,tissue thickness and tissue biomass of the three corals decreased in diverse degrees,with the most severe reduction found in Porites lutea that the zooxanthellae density and tissue biomass decreased by 14.2%and 32.9%,respectively.These results suggest that the reef corals adapt to shading by improving their effective photosynthetic efficiency in short-term light limitation,but the energy transformed by photosynthesis could not meet the metabolic needs of coral growth,thus coral tissue biomass and tissue thickness decrease.

关 键 词：造礁石珊瑚 弱光限制 光生理 永乐环礁 

分 类 号：Q958.8[生物学—动物学]