Data from: Sediment and turbidity associated with offshore dredging increase coral disease prevalence on nearby reefs

In recent decades, coral reef ecosystems have declined to the extent that reefs are now threatened globally. While many water quality parameters have been proposed to contribute to reef declines, little evidence exists conclusively linking specific water quality parameters with increased disease prevalence in situ. Here we report evidence from in situ coral health surveys confirming that chronic exposure to dredging-associated sediment plumes significantly increase the prevalence of white syndromes, a devastating group of globally important coral diseases. Coral health surveys were conducted along a dredging-associated sediment plume gradient to assess the relationship between sedimentation, turbidity and coral health. Reefs exposed to the highest number of days under the sediment plume (296 to 347 days) had two-fold higher levels of disease, largely driven by a 2.5-fold increase in white syndromes, and a six-fold increase in other signs of compromised coral health relative to reefs with little or no plume exposure (0 to 9 days). Multivariate modeling and ordination incorporating sediment exposure level, coral community composition and cover, predation and multiple thermal stress indices provided further confirmation that sediment plume exposure level was the main driver of elevated disease and other compromised coral health indicators. This study provides the first evidence linking dredging-associated sedimentation and turbidity with elevated coral disease prevalence in situ. Our results may help to explain observed increases in global coral disease prevalence in recent decades and suggest that minimizing sedimentation and turbidity associated with coastal development will provide an important management tool for controlling coral disease epizootics.近数十年来，珊瑚礁生态系统(coral reef ecosystems)已出现大幅衰退，全球范围内的珊瑚礁均面临生存威胁。尽管已有多项研究提出诸多水质参数(water quality parameters)可能与珊瑚礁退化相关，但目前鲜有确凿证据能在原位(in situ)条件下，将特定水质参数与病害发生率上升直接关联起来。本研究通过原位珊瑚健康调查(coral health surveys)获取的证据证实，长期暴露于疏浚相关泥沙羽流(dredging-associated sediment plumes)环境，会显著提升白色综合征(white syndromes)的患病率——该类病害是一类具有全球重要性的毁灭性珊瑚病害。研究人员沿疏浚相关泥沙羽流梯度开展珊瑚健康调查，以评估沉积作用(sedimentation)、浊度(turbidity)与珊瑚健康之间的关联。相较于几乎未暴露于泥沙羽流的珊瑚礁（暴露天数为0至9天），暴露于泥沙羽流天数最多的珊瑚礁（296至347天）的病害发生水平高出一倍，这主要由白色综合征患病率升高2.5倍、其他珊瑚健康受损表征升高6倍共同导致。结合泥沙暴露水平、珊瑚群落组成与盖度(coral community composition and cover)、捕食压力(predation)及多项热胁迫指数(thermal stress indices)开展的多变量建模(multivariate modeling)与排序分析(ordination)进一步证实，泥沙羽流暴露水平是导致病害发生率上升及其他珊瑚健康指标受损的核心驱动因素。本研究首次在原位条件下证实，疏浚相关的沉积作用与浊度升高会提升珊瑚病害的患病率。本研究结果或有助于解释近数十年来全球珊瑚病害发生率上升的观测现象，同时表明控制海岸开发带来的沉积与浊度问题，将成为防控珊瑚病害暴发的重要管理手段。