Collaborative Research: RAPID: Nearshore settlement and hydrodynamics in Southern California during El Nino, and the transition to normal ocean conditions: boom and bust?

合作研究：RAPID：厄尔尼诺期间南加州近岸沉降和流体动力学，以及向正常海洋条件的过渡：繁荣与萧条？

• 批准号: 1630459
• 负责人: Jesus Pineda
• 金额: $ 9.9万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-15 至 2018-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1630459&HistoricalAwards=false
• 关键词: Collaborative; Research; RAPID; Nearshore; settlement

Understanding how larvae are transported in the coastal ocean is key for characterizing the population fluctuations of marine organisms. Studies demonstrate that larvae of species that inhabit shallow waters can behaviorally respond to changing oceanographic conditions by moving vertically into currents that can promote their transport to coastal, nearshore habitats where they settle to bottom habitats and complete their life cycle. However, the oceanographic mechanisms that promote such transport, and how they might be impacted by infrequent events such as El Niño, are poorly resolved. Given that El Niño events might increase in frequency and magnitude under climate change, it is imperative to assess how El Niño affects larval transport and larval settlement. To this end, this study will use an unprecedented set of nearshore biological and physical measurements spanning pre-El-Niño, during El Niño, and the predicted return to El Niño neutral conditions, to test mechanistically how larval transport and settlement respond in a nearshore coastal environment. This project will also provide educational and research opportunities for students at the University of San Diego, a liberal arts university. At least one laboratory exercise demonstrating the impacts of El Niño on larval transport and settlement will be developed for undergraduate students, and students will be recruited to participate in all aspects of the project to provide them with hands-on research experience. This research will form the basis for the thesis work of at least one M.S. graduate student. Finally, given that the research falls within a Marine Protected Area, results will be broadly disseminated and shared with coastal managers and the CA Department of Fish and Wildlife.Larval transport and settlement are fundamental processes for understanding the population dynamics of benthic invertebrates. Previous studies and unpublished observations indicate that El Niño events profoundly impact community and population processes, and in Southern California, El Niño effects range from alteration of larval transport and settlement of local populations, to the geographic expansion of subtropical species. This research will test the hypothesis that the current (2015-2016) El Niño event will result in a reduction of barnacle larval transport and settlement in Southern California nearshore habitats. Two mechanisms might be involved; first, a deepening of the thermocline forced by El Niño would result in reduction of larval transport by internal tidal bores, a mechanism that requires shallowing of the thermocline. Second, the distribution of larvae of littoral barnacles would be deeper, more offshore, and less constrained to nearshore habitats during El Niño than in El Niño neutral conditions, resulting in a reduction of nearshore larval abundance and settlement. The effects of El Niño on nearshore circulation, hydrography, larval transport and settlement in Bird Rock, Southern California, will be measured by a) deploying an array of instrumentation to measure temperature, pressure (waves) and currents; b) measuring daily barnacle larval settlement, and; c) assessing cross-shore and depth distribution of invertebrate larvae. These observations will be contrasted with two years of comparable observations taken at Bird Rock in 2014 (El Niño neutral conditions) and 2015 (during El Niño). Additionally, the investigators will measure weekly settlement at Bird Rock, and at Dike Rock, a site 7 km to the north, where previous observations at the end of the 1997/1998 El Niño indicated that barnacle settlement was very high. This will enable the evaluation of the generality of the settlement response as El Niño conditions eclipse, and examination of how settlement varies along a coastline.

了解幼虫如何在沿海海洋中运输是描述海洋生物种群波动的关键。研究表明，栖息在浅水沃茨的物种的幼虫可以在行为上对不断变化的海洋条件作出反应，垂直进入海流，促使它们迁移到沿海、近岸生境，在那里定居在底部生境，完成其生命周期。然而，促进这种迁移的海洋学机制以及它们如何受到厄尔尼诺等罕见事件的影响，却没有得到很好的解决。鉴于厄尔尼诺现象在气候变化的情况下可能会增加频率和规模，因此必须评估厄尔尼诺现象如何影响幼虫迁移和幼虫定居。为此，这项研究将使用一套前所未有的近岸生物和物理测量，涵盖厄尔尼诺前、厄尔尼诺期间和预测的厄尔尼诺中性条件的恢复，从机械上测试幼虫运输和定居在近岸沿海环境中的反应。该项目还将为圣地亚哥大学（一所文科大学）的学生提供教育和研究机会。将为本科生设计至少一个实验室练习，展示厄尔尼诺现象对幼虫迁移和定居的影响，并将招募学生参加该项目的所有方面，使他们获得实际研究经验。这项研究将形成至少一个硕士论文工作的基础。研究生。最后，鉴于研究福尔斯属于海洋保护区，研究结果将广泛传播，并与沿海管理人员和CA渔业和野生动物部共享。幼虫运输和定居是了解底栖无脊椎动物种群动态的基本过程。以往的研究和未发表的观察表明，厄尔尼诺事件深刻影响社区和人口的过程，在南加州，厄尔尼诺影响范围从改变幼虫运输和当地人口的定居点，到亚热带物种的地理扩张。这项研究将测试的假设，目前（2015-2016年）厄尔尼诺事件将导致减少藤壶幼虫运输和定居在南加州近岸栖息地。这可能涉及两种机制;第一，厄尔尼诺现象使温跃层加深，从而减少内部涌潮对幼虫的搬运，这种机制需要使温跃层变浅。其次，与厄尔尼诺中性条件相比，厄尔尼诺期间沿岸的藤壶幼虫的分布将更深、更离岸，并且对近岸栖息地的限制更少，导致近岸幼虫丰度和定居量减少。厄尔尼诺现象对南加州伯德罗克近岸环流、水文地理、幼虫运输和定居的影响将通过以下方式进行测量：a）部署一系列仪器，测量温度、压力（波浪）和海流; B）测量藤壶幼虫每日定居情况; c）评估无脊椎动物幼虫的跨岸和深度分布。这些观测结果将与2014年（厄尔尼诺中性条件）和2015年（厄尔尼诺期间）在伯德岩进行的两年可比观测结果进行对比。此外，调查人员还将测量鸟岩和以北7公里处的堤岩的每周沉降量，以前在1997/1998年厄尔尼诺现象结束时的观测表明，那里的藤壶沉降量非常高。这将使人们能够评价厄尔尼诺现象消失时沉降反应的一般性，并检查沿着海岸线的沉降变化情况。