RAPID: Collaborative Research: Sponge resilience in the face of multiple stressors

在过去的几十年里，世界范围内的珊瑚礁经历了由珊瑚本身主导到海绵或藻类主导的转变。这些变化的原因很复杂，但它们既包括自然压力因素，如疾病和飓风，也包括人类活动的影响，如沿海开发和气候变化。在加勒比海的珊瑚礁上有超过600种海绵，它们扮演着许多重要的生态角色，包括养分循环，为其他珊瑚礁动物提供食物和住所，并产生大量的化合物，这些化合物对控制珊瑚礁上物种的相互作用很重要，并且可能作为潜在的新药。尽管它们对珊瑚礁很重要，但海绵生物学的许多方面仍然未知，包括它们如何对不同类型的压力源作出反应。在美属维尔京群岛的圣托马斯，珊瑚礁暴露在不同程度的人为压力下，这取决于它们与海岸开发的接近程度，这些珊瑚礁上的海绵组合也随着人类影响的程度而变化。2017年9月，圣托马斯岛连续两次遭受5级飓风的袭击。与珊瑚不同，海绵群落在飓风过后会发生什么，我们几乎一无所知。因此，研究小组将结合野外生态学和种群遗传学方法，确定海绵群落如何从这些毁灭性的风暴中做出反应和恢复，以及之前暴露于陆地压力源是否会影响它们的恢复。密西西比大学、阿拉巴马大学和维尔京群岛大学的研究人员将参与这个RAPID项目，并将为学生和博士后研究人员，特别是来自代表性不足群体的研究人员提供培训机会。将向维尔京群岛的资源管理人员提供信息，并向圣托马斯的社区团体提供外联方案。该项目的目标是评估单一压力源（如飓风）与多重压力源（如飓风和陆基污染源）对美国圣托马斯海绵群落的恢复力、恢复和繁殖的影响。鉴于海绵在全球珊瑚礁上的主导地位日益增强，了解海绵对自然和人为压力源的反应变得越来越重要。研究人员将利用来自圣托马斯岛周围几个地点的多年海绵组合数据，这些数据在飓风Irma和Maria之前暴露于当地陆地压力源的水平不同，并评估这些不同组合随时间的变化，从这些破坏性风暴发生后的3个月内开始。研究人员将结合使用自然和实验清理的地块，评估海绵演替的进展，以及藻类的存在是否会干扰海绵的补充和恢复。将收集新个体和附近同种个体的亚样本，评估种群遗传多样性和新个体的潜在来源。该项目获得的数据将为以下方面提供重要见解：在以前暴露于陆基压力源的地点，海绵对飓风的响应弹性、海绵群落演替的开始、演替轨迹的潜在预测因素，以及风暴事件后海绵种群的遗传多样性。这些信息将有助于确定抑制珊瑚恢复的因素和提高珊瑚礁恢复力的潜在方法。

Over the past several decades, coral reefs worldwide have undergone a transition from being dominated by the corals themselves to being dominated by sponges or algae. The causes of these changes are complex, but they include both natural stressors, such as diseases and hurricanes, and impacts from human activities, such as coastal development and climate change. There are over 600 species of sponges on Caribbean coral reefs, and they serve many important ecological roles, including nutrient cycling, providing food and shelter for other reef animals, and producing a tremendous diversity of chemical compounds that are important for controlling species interactions on the reef, and may serve as potential new drugs. In spite of their importance on coral reefs, there are many aspects of sponge biology that remain unknown, including how they respond to different types of stressors. Coral reefs in St. Thomas, in the U.S. Virgin Islands, are exposed to different levels of man-made stressors, depending upon their proximity to coastal development, and the sponge assemblages on these reefs also vary with levels of human impacts. In September 2017, St. Thomas was devastated by two Category 5 hurricanes in a row. Since, unlike corals, virtually nothing is known about what happens to sponge communities in the aftermath of hurricanes, the research team will use a combination of field ecology and population genetics approaches to determine how sponge communities respond and recover from these devastating storms and whether prior exposure to land-based stressors affects their recovery. Researchers at the Universities of Mississippi, Alabama and the Virgin Islands will participate in this RAPID project, and will provide training opportunities for students and postdoctoral researchers, especially from underrepresented groups. Information will be provided to resource managers in the Virgin Islands, along with outreach programs to community groups in St. Thomas.The goal of this project is to assess the impacts of single (e.g., hurricanes) versus multiple (e.g., hurricanes and land-based sources of pollution) stressors on the resilience, recovery, and recruitment of sponge communities in St. Thomas, U.S.V.I. Given the growing dominance of sponges on coral reefs worldwide, understanding the responses of sponges to natural and anthropogenic stressors is increasingly important. The investigators will leverage multiple years of data on sponge assemblages from several sites around the island of St. Thomas that varied in their levels of exposure to local land-based stressors prior to Hurricanes Irma and Maria, and evaluate changes to these diverse assemblages over time, beginning within 3 months of these devastating storms. Using a combination of natural and experimentally cleared plots, the investigators will assess the progress of sponge succession and whether the presence of algae interferes with sponge recruitment and recovery. Subsamples of recruits and nearby conspecifics will be collected to evaluate population genetic diversity and potential sources of new individuals. The data resulting from this project will provide critical insights into sponge resilience in response to hurricanes at sites previously exposed to land-based stressors, the initiation of succession within sponge communities, potential predictors of successional trajectory, and genetic diversity within sponge populations following a storm event. This information will help identify factors that inhibit coral recovery and potential approaches to enhance resilience of coral reefs.