Collaborative Research: Consequences of sub-lethal hypoxia exposure for teleosts tracked with biogeochemical markers: a trans-basin comparison

当水生栖息地的溶解氧浓度低于生物体所需的水平时，就会发生缺氧。全球缺氧事件的频率、持续时间和强度增加，导致海洋和淡水生态系统的健康和功能受损。虽然低氧暴露的潜在影响是严重的，但对鱼类种群和群落的系统性、亚致命性低氧暴露事件的后果知之甚少。该项目的目的是确定在生命早期暴露于亚致死的缺氧是否会导致生长不良，从而增加死亡率。该项目将使用“环境指纹”方法对鱼耳石（耳石）进行回顾性分析，以确定缺氧暴露的时期。该项目将比较缺氧对墨西哥湾、波罗的海和伊利湖不同鱼类的影响，从而检查世界上最大的人为缺氧区域，包括淡水、河口和海洋生态系统。此外，该研究将通过向德克萨斯州南部以西班牙裔和拉丁裔学生为主的高中传播课程材料，提高人们对缺氧相关问题的认识。作为该计划的一部分，将资助两名高中教师参加国家海洋和大气管理局的“海上教师”计划，在那里他们将获得在墨西哥湾北部“死亡地带”进行生物采样的第一手经验，并帮助为更多的高中教师举办教师培训讲习班，以便在课堂上实施与缺氧有关的课程。此外，该项目将通过国际海洋探索理事会和大湖渔业委员会为波罗的海和大湖渔业的关键利益攸关方群体提供重要的基本信息。两名研究生和一名博士后也将得到该项目的部分资助。该项目将采用纳入鱼耳石的长期、永久性标记物，以识别亚致死缺氧暴露的终生模式，远远超出目前使用分子标记物可实现的时间跨度。这项工作将利用地球化学指标的模式，如Mn/Ca和I/Ca纳入耳石，并使用激光烧蚀电感耦合等离子体质谱分析，以确定亚致死缺氧暴露的模式。然后，研究人员将通过长期跟踪和识别幸存者的特征，确定与未暴露的鱼相比，暴露是否会导致不同的生长和生存模式。由于这项工作涉及多个低氧地区的多个物种，它将允许在独特的生态系统之间进行跨系统比较。因此，该项目的结果将利用新的生物地球化学指标，为三个主要盆地缺氧暴露的影响提供前所未有的见解，从而为更全面地了解“死亡区”对沿海资源的影响铺平道路。

Hypoxia occurs when dissolved oxygen concentrations in aquatic habitats drop below levels required by living organisms. The increased frequency, duration and intensity of hypoxia events worldwide have led to impaired health and functioning of marine and freshwater ecosystems. Although the potential impacts of hypoxic exposure are severe, there is little known about the consequences of systemic, sub-lethal exposure to hypoxic events for populations and communities of fishes. The objective of this project is to determine whether sub-lethal exposure to hypoxia during early life stages leads to poor growth and hence increased mortality. This project will use "environmental fingerprint" methods in fish ear stones (otoliths) retrospectively to identify periods of hypoxia exposure. The project will compare consequences of hypoxia exposure in different fish species from the Gulf of Mexico, the Baltic Sea, and Lake Erie, thus examining the largest anthropogenic hypoxic regions in the world spanning freshwater, estuarine, and marine ecosystems. In addition, the research will increase awareness of hypoxia-related issues by disseminating curriculum materials to high schools in southern Texas that are dominated by Hispanic and Latino American students. As a part of this program, two high school teachers will be sponsored to participate in the National Oceanic and Atmospheric Administration "Teacher At Sea" program, where they will gain first-hand experience in biological sampling in the northern Gulf of Mexico "Dead Zone" and help lead teacher training workshops for additional high school teachers to implement hypoxia-related curriculum in their classrooms. In addition, this project will contribute significantly to basic information for critical stakeholder groups in Baltic Sea and Great Lakes fisheries via the International Council for the Exploration of the Sea and the Great Lakes Fisheries Commission. Two graduate students and one post-doc will also be supported in part by this project.This project will employ long-term, permanent markers incorporated into fish otoliths to identify life-long patterns of sub-lethal hypoxia exposure far beyond time spans currently achievable using molecular markers. This work will capitalize on patterns of geochemical proxies such as Mn/Ca and I/Ca incorporated into otoliths and analyzed using laser ablation inductively coupled plasma mass spectrometry to identify patterns of sub-lethal hypoxia exposure. The investigators will then determine whether exposure results in differential growth and survival patterns compared to non-exposed fish by tracking cohorts over time and identifying characteristics of survivors. Because this work involves multiple species in multiple hypoxic regions, it will allow cross-system comparisons among unique ecosystems. The results from this project will thus provide unprecedented insight into effects of hypoxia exposure in three major basins using novel biogeochemical proxies, thereby paving the way for a fuller understanding of the impacts of "dead zones" on coastal resources.