RAPID: Resilience of Caribbean octocorals following Hurricanes Irma and Maria

干扰和随后的恢复一直是珊瑚礁种群动态的关键因素，但在加勒比，硬珊瑚的丰度一直在稳步下降，而藻类的丰度却在增加。 这种定性忽略了这样一种观察，即在一些有定量数据的地点，珊瑚礁（海扇和海羽）的丰度有所增加。 对这些数据的仔细检查显示，珊瑚有时也会减少，但与硬珊瑚不同的是，它们恢复了，现在至少在某些地方比30年前更丰富。这些生物丰度的变化似乎是由于珊瑚礁的适应力更强。飓风厄玛和玛丽亚对美属维尔京群岛圣约翰南岸海岸造成的破坏。提供了一个了解这些过程的窗口。 过去30年来一直监测这些珊瑚礁上硬珊瑚的丰度，过去4年来一直跟踪珊瑚礁。将研究珊瑚礁上新开辟的空间的殖民化，以确定是否可以预期丰度的进一步变化，并了解珊瑚礁种群更大弹性的基础。 描述珊瑚礁相对于硬珊瑚的复原力将对加勒比珊瑚礁在世界上日益增加的压力下的命运产生影响。这对决策者和管理人员很重要，因为硬珊瑚和珊瑚礁提供的生态系统服务大不相同。除了它对我们对珊瑚礁过程的基本理解的影响外，该赠款还将支持研究生的培训。珊瑚礁被认为是50多年来受干扰驱动的系统，干扰被认为是维持珊瑚礁群落多样性的重要因素。然而，过去30年的特点是石珊瑚丰度下降，往往与飓风和漂白事件等急性事件有关。了解这些事件期间发生的扰动和随后恢复的影响，对于了解过去30年来发生的珊瑚礁结构变化至关重要。 在有数据的网站，在相对丰富的石珊瑚和珊瑚的变化似乎与干扰，其次是珊瑚恢复和缺乏石珊瑚恢复。这种变化必须反映幼虫供应，定居和/或生存的变化，这些差异应该是最大的干扰。飓风伊尔玛和玛丽亚对圣约翰南海岸的影响提供了一个机会，表征招聘后的干扰，并确定可能限制成功招聘当代珊瑚礁的过程。在过去4年里，已经有关于珊瑚和石珊瑚物种丰度的数据，年度普查提供了关于珊瑚补充和存活的数据，以及珊瑚丰度的物种一级特征。招聘和生存也正在与栖息地的空间复杂性在毫米和厘米尺度和飓风驱动的空间复杂性的变化的影响也将进行评估。干扰的频率和强度至少将保持在历史或更高的水平。 从之前和现在的干扰后的数据的比较将提供一个强大的评估的恢复力的珊瑚和scleractinians和招聘和招聘生存在其相对弹性的作用。因此，飓风厄玛和玛丽亚的影响为未来珊瑚礁的性质提供了一个窗口。

Disturbance and subsequent recovery have been key factors in the dynamics of coral reef populations, but in the Caribbean, there has been a steady decline in the abundance of hard corals accompanied by increased abundance of algae. This characterization overlooks the observation that at some sites for which there are quantitative data, the abundances of octocorals (sea fans and sea plumes) have increased. Closer inspection of those data reveals that octocorals have also declined at times, but unlike hard corals, they recovered and are now more abundant in at least some locations than 30 years ago. The change in abundances of these organisms would appear to due to the greater resilience of octocorals. The damage inflicted by Hurricanes Irma and Maria on the south shore of St. John, U.S. Virgin Is. provides a window into these processes. Abundances of hard corals on these reefs have been monitored for the past 30 years and the octocorals have been followed for the past 4 years. Colonization of the newly opened space on the reef will be studied to determine if further shifts in abundances can be expected and to understand the basis for the greater resilience of octocoral populations. Characterizing the resilience of octocorals relative to hard corals will have implications for the fate of Caribbean reefs in a world subject of increasing levels of stress. This will be of importance to policy makers and managers, because hard corals and octocorals provide substantially different ecosystem services. In addition to its impact on our fundamental understanding of reef processes, the grant will support the training of graduate students.Coral reefs have been recognized to be disturbance driven systems for over 50 years and disturbance has been considered to be important in maintaining diversity of reef communities. However, the past 30 years has been characterized by declines in the abundances of scleractinians, often associated with acute events such as hurricanes and bleaching events. A knowledge of the effects of disturbance and subsequent recovery that occurs during these events is critical to understanding the changes in reef structure that have occurred in the last 30 years. At sites for which there are data, changes in the relative abundance of scleractinians and octocorals appear to coincide with disturbance followed by octocoral recovery and a lack of scleractinian recovery. This change must reflect changes in larval supply, settlement, and/or survival, and those differences should be greatest following disturbance. The effects of Hurricanes Irma and Maria on the south shore of St. John provide the opportunity to characterize recruitment following disturbance and identify the processes that may limit successful recruitment on contemporary reefs. Data are already available on the abundance of octocoral and scleractinian species over the past 4 years, and annual censuses have provided data on octocoral recruitment and survival and species level characterizations of octocoral abundances. Recruitment and survival are also being related to spatial complexity of the habitat at the scale of mm and cm and the effects on hurricane driven changes in that spatial complexity will also be assessed. The frequency and intensity of disturbances will at the least continue at historical or greater levels. The comparison of data from before and now after disturbance will provide a powerful assessment of the resilience of octocorals and scleractinians and the role of recruitment and recruit survival in their relative resilience. Thus the effects of Hurricanes Irma and Maria provide a window on the nature of future reefs.