Department of Biology, Valdosta State University, 1500 N. Patterson St, Valdosta, GA 31698, United States.
Aquat Toxicol. 2010 Apr 15;97(2):125-33. doi: 10.1016/j.aquatox.2009.12.021. Epub 2010 Jan 4.
Land-based sources of pollution have been identified as significant stressors linked to the widespread declines of coral cover in coastal reef ecosystems over the last 30 years. Metal contaminants, although noted as a concern, have not been closely monitored in these sensitive ecosystems, nor have their potential impacts on coral-algal symbioses been characterized. In this study, three species of laboratory-reared scleractinian corals, Acropora cervicornis, Pocillopora damicornis, and Montastraea faveolata each containing different algal symbionts (Symbiodinium A3, C1 and D1a, respectively) were exposed to copper (ranging from 2 to 20microg/L) for 5 weeks. At the end of the exposure period, copper had accumulated in the endosymbiotic dinoflagellate ("zooxanthellae") and animal tissue of A. cervicornis and the animal tissue of M. faveolata; however, no copper accumulation was detected in the zooxanthellae or animal tissue of P. damicornis. The three coral species exhibited significantly different sensitivities to copper, with effects occurring in A. cervicornis and P. damicornis at copper concentrations as low as 4microg/L. Copper exposure affected zooxanthellae photosynthesis in A. cervicornis and P. damicornis, and carbonic anhydrase was significantly decreased in A. cervicornis and M. faveolata. Likewise, significant decreases in skeletal growth were observed in A. cervicornis and P. damicornis after copper exposure. Based on preliminary results, no changes in Symbiodinium communities were apparent in response to increasing copper concentration. These results indicate that the relationships between physiological/toxicological endpoints and copper accumulation between coral species differ, suggesting different mechanisms of toxicity and/or susceptibility. This may be driven, in part, by differences in the algal symbiont communities of the coral species in question.
陆地污染源已被确定为导致过去 30 年来沿海珊瑚礁生态系统中珊瑚覆盖范围广泛减少的重要胁迫因素。金属污染物虽然被认为是一个关注点，但在这些敏感的生态系统中并没有被密切监测，也没有描述它们对珊瑚-藻类共生体的潜在影响。在这项研究中，三种实验室培养的石珊瑚，即 Acropora cervicornis、Pocillopora damicornis 和 Montastraea faveolata，每种珊瑚都含有不同的共生藻（分别为 Symbiodinium A3、C1 和 D1a），分别暴露于铜（浓度范围为 2 至 20μg/L）5 周。在暴露期结束时，铜已在共生的甲藻（“虫黄藻”）和 A. cervicornis 的动物组织以及 M. faveolata 的动物组织中积累；然而，在 P. damicornis 的虫黄藻或动物组织中未检测到铜积累。这三种珊瑚物种对铜表现出明显不同的敏感性，A. cervicornis 和 P. damicornis 在铜浓度低至 4μg/L 时就出现了影响。铜暴露影响了 A. cervicornis 和 P. damicornis 的虫黄藻光合作用，并且 A. cervicornis 和 M. faveolata 的碳酸酐酶显著降低。同样，在铜暴露后，A. cervicornis 和 P. damicornis 的骨骼生长也明显减少。根据初步结果，在应对铜浓度增加时，共生藻群落没有明显变化。这些结果表明，不同珊瑚物种之间生理/毒理学终点与铜积累之间的关系不同，表明存在不同的毒性和/或易感性机制。这可能部分是由于所研究的珊瑚物种的共生藻群落存在差异。
