RUI: Collaborative Research: Linking physiological thermal thresholds to the distribution of lobster settlers and juveniles

温度是决定海洋生物分布的一个关键因素。然而，在许多情况下，温度范围（热耐受性）只知道成虫，而不知道从浮游生物过渡到海底的未成熟阶段。这项研究是为了测试温度是如何影响幼虫在哪里定居的。缅因湾的美洲龙虾（Homarus americanus）被用作测量幼虫耐热性的模型系统，并将其与田间小龙虾的分布联系起来。目前，龙虾幼虫更有可能经历相对较冷的温度，而不是热应激，幼虫对低于12°C的温度敏感，似乎仅限于温暖的浅水。随着水温的升高，沉降和幼鱼分布扩展到更深的水域，这表明它们从冷应激中解脱出来。该项目通过首次探索野生捕获的幼虫的热敏感性，促进了对海洋温度升高引起的物种分布变化的理解。这些信息为模拟气候变化情景下的幼虫生存能力提供了热阈值。了解幼虫对温度的反应是预测气候变化对北美最有价值的商业渔业之一的影响的基础。该项目支持培训来自小型学院（胡德学院和新英格兰大学）的本科生实习生和一名硕士生，并将他们与研究机构（毕格罗海洋科学实验室）联系起来。教师培训是与新英格兰大学海洋科学中心合作进行的。这项研究的结果正在与利益攸关方分享，并为龙虾渔业的科学管理作出贡献。该项目首次研究了幼虫期的热应激如何决定幼鱼的分布，采用了相关和实验相结合的方法，包括测量自然野外生境中部署的幼虫的生化应激指标。中心假设是单个浮游生物幼虫的生理控制着野外中尺度的定居模式。目的是确定是否有一个因果关系之间的潜在生理和热敏性的有机体和分布的早期生命阶段。将在温度高于和低于建议的幼虫最低温度阈值12°C的不同深度评估幼虫供应、沉降和幼鱼丰度。使用常规方法的实验室实验正在确定野生捕获的幼虫的耐热性以及它们如何随个体发生而变化。通过多种生理参数，如耗氧量和有氧范围的测量，以及热应激的生化分析（HSP70、AMPK和SIRT），可以确定上下热最佳值。为了将生理学与定居模式联系起来，在温度高于或低于12°C的地点，将笼中的IV期幼虫和V期幼鱼放养在野外。正在通过测量生长、死亡率和热应激的生化指标来评估对笼捕龙虾的致死和亚致死效应。这是首次关注野生幼虫的热耐受性的研究，这对理解海洋无脊椎动物幼虫的沉降具有广泛的意义。该项目由生物海洋学（OCE）和促进竞争性研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Temperature is one critical factor that determines the distribution of marine organisms. However, in many cases temperature ranges (thermal tolerances) are only known for adults, but not for the immature stages that transition from the plankton to the bottom. This study is testing how temperature affects where larvae are settling. The American lobster (Homarus americanus) in the Gulf of Maine is serving as a model system to measure the thermal tolerance of the larvae and link this to the distribution of young lobsters in the field. Presently, lobster larvae are more likely to experience relatively cold temperatures than heat stress and larval settlement appears to be restricted to warmer shallow waters by a sensitivity to temperatures below 12°C. As water temperature has increased, settlement and juvenile distribution have expanded into deeper waters suggesting a release from cold stress. This project is advancing the understanding of shifting species distributions in response to increasing ocean temperatures by exploring thermal sensitivity in wild-caught larvae for the first time. This information is providing thermal thresholds for modeling larval viability in response to climate change scenarios. Understanding the larvae’s responses to temperature is fundamental to predicting the impact of climate change on one of the most valuable commercial fisheries in North America. The project is supporting training of undergraduate interns and a master’s student from small colleges (Hood College and University of New England) and connecting them with a research institution (Bigelow Laboratory for Ocean Sciences). Teacher training is occurring in collaboration with the Marine Science Center at the University of New England. Results from this study are being shared with stakeholders and contributing to science-based management of the lobster fishery.This project is the first to examine how thermal stress on a larval stage determines juvenile distributions using a combination of correlative and experimental approaches that includes measuring biochemical stress indicators in larvae deployed in natural field habitats. The central hypothesis is that the physiology of individual planktonic larvae controls meso-scale settlement patterns in the field. The goal is to ascertain if there is a causal relationship between the underlying physiology and thermal sensitivity of the organism and the distribution of early life stages. Larval supply, settlement and juvenile abundances will be assessed at different depths with temperatures above and below the proposed minimum temperature threshold of 12°C for larvae. Laboratory experiments using conventional methods are determining thermal tolerances in wild-caught larvae and how they change with ontogeny. The upper and lower thermal optima are being resolved using multiple physiological parameters such as measurements of oxygen consumption and aerobic scope, and biochemical assays of thermal stress (HSP70, AMPK, and SIRT). To link physiology to settlement patterns, caged stage IV larvae and V juveniles are being deployed in the field at sites with temperatures above and below 12°C. Lethal and sub-lethal effects on caged lobsters are being evaluated through measures of growth, mortality and biochemical markers of thermal stress. This is the first study to focus on the thermal tolerance of wild larvae, which has broad implications for understanding settling in marine invertebrate larvae.This project is jointly funded by Biological Oceanography (OCE) and the Established Program to Stimulate Competitive Research (EPSCoR).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.