RAPID collaborative research: Historic freshwater input and hypoxia effects on zooplankton populations of the northern Gulf of Mexico

自2003年以来，PI在墨西哥湾北方进行了5次夏季巡航，使用高分辨率采样来确定物理结构、缺氧和远洋浮游动物分布之间的空间明确关系。在深水地平线泄漏事件发生后，PI获得了NSF快速反应赠款，以测量与前5次巡航相同空间域中的浮游动物群落组成和丰度。他们现在拥有关于墨西哥湾北方温度、盐度、氧气、浮游植物、浮游动物和鱼类的最全面的天气数据集。这些努力的合成产品包括：生物量大小谱模型，用于评估人类活动对浮游生物和鱼类食物网的影响;浮游植物、微型浮游动物、中型浮游动物和鱼类的物种组成;鱼类饮食数据;以及鱼类生长潜力模型，用于根据食物供应和物理条件定量评估鱼类生境需求。在过去几个月里，一直持续到2011年夏季，向海湾输送的淡水量达到了历史最高水平，形成了世纪以来最大的分层缺氧水柱（http：//www.cop.noaa.gov/gulf_hypoxia_forecast/）。 在切萨皮克湾的PI的早期研究表明，缺氧的垂直程度（%水柱）可能是主要因素造成的浮游动物的位置和大小分布的变化。 浮游动物种群垂直结构的变化直接影响到鱼类的营养转移，因为它们比食虫性捕食者更能耐受低氧。PI建议利用计划的调查巡航，从7月25日至8月2日收集和分析研究区域（LA-TX大陆架）的浮游动物。知识成果：缺氧对底栖生物的影响已得到充分研究，其影响已基本得到了解。浮游生物，如浮游动物，提出了一个更困难的问题，因为他们能够使用的行为，以避免缺氧沃茨，这种行为是密切相关的个别物种的缺氧耐受性。缺氧导致水柱的生物分层，造成营养转移尚未量化的影响。PI先前的工作提供了一个高分辨率，空间上明确的数据库，以与2011年预期的缺氧进行比较，并解决有关这些影响的具体假设。更广泛的影响：考虑到墨西哥湾商业渔业（约占美国总上岸量的20%，约9.91亿美元）和休闲渔业（约占全国咸水捕捞支出的30%，并支持全国近25%的休闲咸水就业机会）的经济重要性。角点实验室是国家科学基金会海洋科学教育卓越中心（NSF-COSEE）和本科生经验（REU）计划的一部分。在可能的情况下，在这个NSF快速反应赠款，PI将涉及REU本科学生和教师在他们的研究。所有数据都将及时提交给BCO-DMO数据库，以便更广泛的科学界可以使用。

Since 2003 the PIs have conducted 5 summer cruises in the northern Gulf of Mexico using high-resolution sampling to define the spatially-explicit relationships between physical structure, hypoxia and pelagic zooplankton distributions. After the Deepwater Horizon spill, the PIs received a NSF Rapid Response grant to measure zooplankton community composition and abundance in the same spatial domain as the previous 5 cruises. They now have one of the most comprehensive, synoptic data sets on temperature, salinity, oxygen, phytoplankton, zooplankton and fish in the northern Gulf of Mexico. Synthetic products from these efforts include biomass size spectrum models which have been used to assess anthropogenic effects on planktonic and fish food-webs; the species composition of phytoplankton, microzooplankton, mesozooplankton, and fish; fish diet data; and fish growth potential models to quantitatively assess fish habitat requirements based on food availability and physical conditions. For the past several months and continuing into summer 2011, the amount of freshwater delivery to the Gulf has been of historic proportions, creating the largest stratified and hypoxic water column seen in a century (http://www.cop.noaa.gov/gulf_hypoxia_forecast/). Earlier studies by the PIs in Chesapeake Bay suggest that vertical extent of hypoxia (% water column) may be the main factor causing shifts in both location and size distribution of zooplankton. Change in the vertical structure of zooplankton populations directly impacts trophic transfer to fish, since they are more tolerant of low oxygen than their zooplanktivorous predators. The PIs propose to take advantage of a planned survey cruise to collect and analyze zooplankton in the study area (LA-TX shelf) from 25 July to 2 August. Intellectual Merit: The impact of hypoxia on benthic organisms has been well-studied and the impacts are largely understood. Pelagic organisms, such as zooplankton, present a more difficult problem as they are able to use behavior to avoid hypoxic waters and this behavior is tightly related to the hypoxia tolerance of individual species. Hypoxia results in water columns that are biologically stratified, causing as yet unquantified impacts on trophic transfer. The PIs' prior work provides a high-resolution, spatially explicit database to compare with the anticipated hypoxia of 2011 and address specific hypotheses about these effects. Broader Impacts : Given the economic importance of the Gulf of Mexico commercial fisheries (about 20% of the U.S. total landings representing about $991 million) and recreational fishing (generating ~30% of the nation's saltwater fishing expenditures and supporting nearly 25% of the nation's recreational saltwater jobs). The Horn Point Laboratory is part of the National Science Foundation's Center for Ocean Sciences Education Excellence (NSF-COSEE) and Experience for Undergraduates (REU) programs. Where possible in this NSF RAPID response grant, the PIs will involve REU undergraduate students and teachers in their research. All data will be submitted to the BCO-DMO database in a timely manner so they will be available to the larger scientific community.