三亚礁区普哥滨珊瑚对海水悬浮物的生理适应

Physiological acclimatization of the scleractinian coral Porites pukoensis to suspended solids in Sanya coral reefs

为了了解海水悬浮物质量浓度的升高对造礁石珊瑚的生存影响,于2020年5−9月期间,调查了三亚3个礁区(崖州湾、凤凰岛和西岛)的海水悬浮物质量浓度,测定了礁区中普哥滨珊瑚(Porites pukoensis)及其共生虫黄藻的生理指标,并筛选了敏感生物标志物,用以评价悬浮物对普哥滨珊瑚的影响程度。结果表明,崖州湾礁区的海水悬浮物月均质量浓度为13.7~19.4 mg·L^(−1),其含量显著高于凤凰岛(1.9~8.8 mg·L^(−1))和西岛(0.7~5.3 mg·L^(−1))。相关性分析表明,海水悬浮物浓度与共生虫黄藻的密度(R=0.27,P<0.05)和一氧化氮合成酶活力(R=0.27,P<0.05)均呈显著正相关,而与共生虫黄藻的谷胱甘肽S−转移酶活力呈显著负相关。因此,普哥滨珊瑚可能通过共生虫黄藻密度和NOS活力的诱导及其GST活力的抑制来适应悬浮物浓度较高的礁区环境。此外,本研究构建的综合生物标志物响应(IBR)指数具有崖州湾>凤凰岛>西岛的特征,与礁区悬浮物含量趋势相一致,提示IBR指数能够为珊瑚礁生态风险评估提供理论基础。

Elevated concentrations of suspended solids in seawater threaten the survival of scleractinian corals,but little is known about the mechanism of this phenomenon.During May-September 2020,a survey was made of the concentration of suspended solids in seawater in the coral reef areas of Yazhou Bay,Phoenix Island and West Island in Sanya,Hainan,China and the physiological indexes of the scleractinian coral Porites pukoensis and its Symbiodiniaceae symbionts were determined,from which sensitive biomarkers were screened to evaluate the effect of suspended solids on P.pukoensis.The results showed that the concentration of suspended solids in the seawater of Yazhou Bay reef area was 13.7−19.4 mg·L^(−1),which was significantly higher than that in Phoenix Island(1.9−8.8 mg·L^(−1))and West Island(0.7−5.3 mg·L^(−1)).The correlation analysis revealed significant positive correlations between suspended solids and the symbiotic density(R=0.27,P<0.05)or nitric oxide synthase activities(R=0.27,P<0.05),while the glutathione S-transferase activities in the symbionts were significantly negatively correlated with the concentration of the suspended solids.All these results suggest that P.pukoensis is adapted to the reef environment with a high concentration of suspended solids through the induction of symbiotic density and NOS activity and the inhibition of GST activity.Moreover,the integrated biomarker response(IBR)index established herein is in the descending order of Yazhou Bay>Phoenix Island>West Island,which is consistent with the order of the contents of the suspended solids in this coral reef area,indicating that the IBR index can be used for ecological risk assessment of coral reefs.