RAPID: Mass Mortality of the Keystone Herbivore Diadema antillarum Underway around the Caribbean Sea

长刺海胆（迪亚德马antillarum）是整个加勒比海珊瑚礁上的重要生物。这些海胆以藻类为食，从而有助于防止藻类过度生长，形成珊瑚礁。从1983年到1984年，一次死亡事件导致平均97%的长棘海胆死亡，并导致许多珊瑚礁上的主导地位转向藻类。这一事件进展迅速，仅在13个月内就蔓延到整个加勒比地区，原因从未查明。类似的事件目前正在发生。该项目解决了三个相互关联的科学问题，以优化从这一临时事件中可以快速学到的东西：1）什么样的海胆种群特征或环境条件可能导致这一事件，它们是否像地球仪过去的海胆死亡事件？2)如果病原体是造成目前死亡事件的原因，那么它是什么？它能通过海水传播吗？3)无论造成这一死亡事件的病原体是病原体、毒素还是其他什么，它在海水中能存活多久，海洋学模型能否用来解释它的分布并预测它未来的传播？ 这一事件提供了一个难得的机会，以研究一个暂时的情况下，不可能在事件结束后。对这些关键问题的回答具有更广泛的社会影响，因为它可以增进我们对长刺海胆（致病因子）的了解;为当地管理实践和种群监测计划提供信息;提高孵化场饲养的动物的生存机会，这些动物将在珊瑚礁恢复工作中发挥关键作用。首先，调查人员正在从正在经历死亡和尚未受到影响的地点收集人口和环境数据。第二，为了优化诊断评估和确定病因的进展，正在对正常和患病的海胆进行组织学评估。第三，为了确定任何病原体，研究人员正在评估健康和患病海胆的微生物组和病毒组。同样，导致大体异常的宿主转录组分析可能揭示动物对感染性或非感染性因子的反应。虽然怀疑有病原体，但对受影响和未受影响地点的化学水平进行比较分析，可以提供关于可能导致迪亚德马压力和免疫抑制的污染水平的宝贵信息。研究人员正在使用围隔生态系统水的切向流过滤来研究潜在的传播模式以及与任何推定病原体的联系。他们正在利用现有的生物物理模型来描述疾病和污染物在更广泛的加勒比海的传播。该模型将预测可能的路线和速度，一个紧急的病原体和/或污染物将旅行，如果它仍然在水柱内的可行性或通过航道旅行。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

The long-spined sea urchin (Diadema antillarum) is an important organism on coral reefs throughout the Caribbean. These urchins feed on algae, thereby helping to keep it from overgrowing the hard corals that form coral reefs. From 1983-1984, a mortality event killed on average 97% of the long-spined urchins and led to a shift in dominance to algae on many coral reefs. That event proceeded rapidly, spreading across the Caribbean in just 13 months and the cause was never identified. A similar event is currently unfolding. This project addresses three interconnected science questions to optimize what can quickly be learned from this temporary event: 1) What urchin population characteristics or environmental conditions may have led to this event and are they like past urchin mortality events around the globe? 2) If a pathogen is responsible for the current mortality event, what is it and can it be transmitted through seawater? 3) Whether the agent responsible for this mortality event is a pathogen, toxin, or something else, how long does it remain viable in seawater, and can oceanographic models be used to explain its distribution and predict its future spread? This event provides a rare opportunity to study a temporary situation in ways not possible after the event is over. Answers to these key questions have broader societal impacts by advancing our knowledge of long-spined urchins, the disease- causing agent; informing local management practices and population monitoring programs; and improving the chance of survival of hatchery-reared animals that will play a critical role in coral reef restoration efforts.This project addresses three project goals that will optimize what we can learn from this event quickly. First, the investigators are collecting demographic and environmental data from sites that are experiencing mortality and those not yet affected. Second, to optimize diagnostic evaluations and progress toward determination of etiology, histologic assessment of both normal and diseased urchins are being performed. Third, to identify any etiological agent, the investigators are assessing the microbiome and virome of healthy and diseased urchins. Similarly, host transcriptome analyses leading up to gross abnormalities may reveal animal responses to infectious or non-infectious agents. Although a pathogen is suspected, comparative analysis of chemical levels among impacted and non-impacted sites can provide valuable information on contamination levels potentially contributing to stress and immunosuppression in Diadema. The investigators are using tangential flow filtration of mesocosm water to investigate the potential mode(s) of transmission and link to any putative pathogens. They are leveraging existing biophysical models to describe the spread of the disease and contaminants in the wider Caribbean Sea. The models will predict the likely routes and speed that an emergent pathogen and/or contaminant would travel if it remained viable within the water column or travels via shipping lanes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.