Collaborative Research: Pattern and process in the abundance and recruitment of Caribbean octocorals

珊瑚礁暴露在各种自然和人为干扰中，生态系统退化的后果已被广泛宣传。然而，报告的变化偏向鱼类和石珊瑚，对于加勒比海珊瑚礁，这种偏向最明显的例子是八角珊瑚(“软珊瑚”)。尽管珊瑚礁资源丰富，在许多加勒比珊瑚礁中占主导地位，但由于既难以确定它们的数量，又难以量化它们的丰富程度，因此很少将它们纳入研究范围。在一些地方，有令人信服的证据表明，软珊瑚的数量增加了，尽管石珊瑚已经变得不那么常见了。这表明，软珊瑚比石珊瑚对影响珊瑚的各种干扰更具弹性。研究这些变化的最佳珊瑚礁是那些已经研究了几十年的珊瑚礁，可以为最近发生的事件提供十年背景，在这方面，美属维尔京群岛圣约翰的珊瑚礁是独一无二的。对珊瑚礁上的石珊瑚的研究始于1987年，对软珊瑚的研究始于2014年。这提供了无与伦比的平台，以评估八珊瑚丰度和补充的模式；确定这些珊瑚礁上正在发生的变化模式，并确定造成八珊瑚种群恢复能力的过程。该项目将把软珊瑚监测从4年延长到8年，并将在这一框架内审查幼年珊瑚的作用，以及它们对海底粗糙度、海水流动和海藻的反应，以决定软珊瑚的成功。这项工作还将评估飓风伊尔玛和玛丽亚的破坏性影响是否改变了变化的模式。与这些努力相协调，该项目将与当地高中密切结合，在那里，研究人员将主办海洋生物学俱乐部，并为其学生和教师提供独立学习的机会。将为本科生和研究生以及博士后研究员提供独特的培训机会，他们都将在圣约翰学习和工作，调查人员将通过在佛罗里达群岛举办的动手研讨会培训珊瑚礁研究人员识别软珊瑚的物种。了解不断变化的环境条件将如何影响主要生物群的群落结构是定义21世纪的生态目标。这些条件对珊瑚礁的整体影响将在美属维尔京群岛圣约翰的维尔京群岛国家公园内的浅礁上进行研究，这是该地区对珊瑚礁群落动态进行的最长、最长期的研究之一。在NSF-LTREB的支持下，调查人员自1987年以来一直在研究该地区石珊瑚群落的长期变化，并在2014年利用NSF-OCE的支持建立了对这一年代际观的八珊瑚“覆盖”。本项目从这一独特的被飓风伊尔玛和玛丽亚影响的历史延伸到将八珊瑚共生学放在十年的背景下，调查人员利用丰富的遗产数据来更好地了解加勒比珊瑚礁的现在和近期的未来。这个为期四年的项目将同时在两个方面取得进展：第一，将对八珊瑚群落的时间序列分析从四年延长到八年，以表征群落结构变化的模式和速度；第二，开展一项以假设为导向的实验方案，重点研究八珊瑚的定居，以揭示允许八珊瑚在当今珊瑚礁上比硬珊瑚更有效地在底质上定居的机制。具体地说，研究人员将针对四个假设进行测定和操控实验，重点是：(1)生境复杂性在区分八珊瑚和硬珊瑚的招募生态位方面的作用，(2)在调节定居后成功的招募生态位方面的作用，(3)藻类草坪和大型藻类的竞争在决定八珊瑚和硬珊瑚新生物的成功与否方面，以及(4)八珊瑚树冠在调节颗粒和幼体向海底流动方面的作用。这项研究的结果将被综合起来，以评估在当今加勒比海珊瑚礁上，促使章鱼和珊瑚具有更高生态弹性的因素。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Coral reefs are exposed to a diversity of natural and anthropogenic disturbances, and the consequences for ecosystem degradation have been widely publicized. However, the reported changes have been biased towards fishes and stony corals, and for Caribbean reefs, the most notable example of this bias are octocorals ("soft corals"). Although they are abundant and dominate many Caribbean reefs, they are rarely included in studies due to the difficulty of both identifying them and in quantifying their abundances. In some places there is compelling evidence that soft corals have increased in abundance, even while stony corals have become less common. This suggests that soft corals are more resilient than stony corals to the wide diversity of disturbances that have been impacting coral corals. The best coral reefs on which to study these changes are those that have been studied for decades and can provide a decadal context to more recent events, and in this regard the reefs of St. John, US Virgin Islands are unique. Stony corals on the reefs have been studied since 1987, and the soft corals from 2014. This provides unrivalled platform to evaluate patterns of octocoral abundance and recruitment; identify the patterns of change that are occurring on these reefs, and identify the processes responsible for the resilience of octocoral populations. The project will extend soft coral monitoring from 4 years to 8 years, and within this framework will examine the roles of baby corals, and their response to seafloor roughness, seawater flow, and seaweed, in determining the success of soft corals. The work will also assess whether the destructive effects of Hurricanes Irma and Maria have modified the pattern of change. In concert with these efforts the project will be closely integrated with local high schools at which the investigators will host marine biology clubs and provide independent study opportunities for their students and teachers. Unique training opportunities will be provided to undergraduate and graduate students, as well as a postdoctoral researcher, all of whom will study and work in St. John, and the investigators will train coral reef researchers to identify the species of soft corals through a hands-on workshop to be conducted in the Florida Keys.Understanding how changing environmental conditions will affect the community structure of major biomes is the ecological objective defining the 21st century. The holistic effects of these conditions on coral reefs will be studied on shallow reefs within the Virgin Islands National Park in St. John, US Virgin Islands, which is the site of one of the longest-running, long-term studies of coral reef community dynamics in the region. With NSF-LTREB support, the investigators have been studying long-term changes in stony coral communities in this location since 1987, and in 2014 NSF-OCE support was used to build an octocoral "overlay" to this decadal perspective. The present project extends from this unique history, which has been punctuated by the effects of Hurricanes Irma and Maria, to place octocoral synecology in a decadal context, and the investigators exploit a rich suite of legacy data to better understand the present and immediate future of Caribbean coral reefs. This four-year project will advance on two concurrent fronts: first, to extend time-series analyses of octocoral communities from four to eight years to characterize the pattern and pace of change in community structure, and second, to conduct a program of hypothesis-driven experiments focused on octocoral settlement that will uncover the mechanisms allowing octocorals to more effectively colonize substrata than scleractinian corals on present day reefs. Specifically, the investigators will conduct mensurative and manipulative experiments addressing four hypotheses focusing on the roles of: (1) habitat complexity in distinguishing between octocoral and scleractinian recruitment niches, (2) the recruitment niche in mediating post-settlement success, (3) competition in algal turf and macroalgae in determining the success of octocoral and scleractian recruits, and (4) role of octocoral canopies in modulating the flux of particles and larvae to the seafloor beneath. The results of this study will be integrated to evaluate the factors driving higher ecological resilience of octocorals versus scleractinians on present-day Caribbean reefs.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.