Ocean Acidification-Category 1- Impact of ocean acidification on survival of early life stages of planktonic copepods in the genus Calanus in the northern

虽然人们对世界海洋酸化的预测影响的关注集中在钙化生物上，但非钙化浮游生物也可能很脆弱。在这个项目中，研究者将评估海洋酸化对高纬度海洋中三种浮游桡足动物（Calanus属）繁殖成功的潜在影响。C. finmarchicus在北大西洋大部分沿海和深海的中浮游动物生物量中占主导地位。C. glacialis和较大的C. hyperboreus是北冰洋最丰富的浮游桡足类。以往的研究表明，海水中CO2的增加和pH的降低严重抑制了C. finmarchicus卵的孵化成功，但只是在极端水平下进行了测试。研究者实验室的初步结果表明，当pH值在7.9和7.5之间对应的海水二氧化碳浓度增加时，C. finmarchicus的孵化成功率大大降低。对地表pH值在下个世纪可能下降到7.7-7.8的预测，如果这些初步结果得到证实，就会对卡兰纳斯种群动态产生影响。例如，C. finmarchicus目前正处于其活动范围的南部边缘，即缅因湾。较高的表层温度和较低的pH值可能会抑制夏末/秋季开花期间的繁殖成功，而PI假设是维持该地区越冬种群的关键。研究人员将从缅因湾收集C. finmarchicus雌虫，并在加拿大同事的协助下，从圣劳伦斯河口下游深处收集C. glacialis和C. hyperboreus雌虫。他们将进行实验室实验，在控制天然海水和一系列严格控制二氧化碳浓度、pH值和温度的处理下，测量鹦鹉螺的孵化成功率、发育和生长阶段，以代表北方海洋可能的未来状态。在一次研究巡航中，研究人员将测量缅因湾（包括其深层盆地）表面和深处的二氧化碳分压和pH值。该研究将评估一个假设，即预测北部海洋二氧化碳水平的增加将影响Calanus物种的种群动态。利用研究巡航的结果和最近开发的基于个体的1-D生命周期模型，PI将详细探索缅因州湾较高温度和较低表面和深层pH值对C. finmarchicus种群动态的影响。更广泛的影响：在北大西洋和北冰洋食物网中，富含脂质的Calanus物种被认为是初级生产和更高营养水平之间的关键中间环节。较高的表面温度和较低的pH值对繁殖成功的影响可能会导致北部海洋中上层生态系统能量转移和结构的深刻变化。在缅因湾，C. finmarchicus是鲱鱼、沙枪鱼、鲭鱼以及濒临灭绝的北露脊鲸的主要猎物，因此需要对海洋酸化对其种群动态的影响进行彻底的评估。本研究将为研究生和本科生实习生提供跨学科的培训。数据将存放在一个公认的数据存档中心，结果将通过在科学会议上的报告和同行审查的研究文章传播。公众宣传将作为缅因湾研究所社区活动的一部分，包括与缅因州五年级和六年级学生的科恩互动学习中心相关的学习机会。

While attention concerning impacts of predicted acidification of the world's oceans has focused on calcifying organisms, non-calcifying plankton may also be vulnerable. In this project, the investigator will evaluate the potential for impacts of ocean acidification on the reproductive success of three species of planktonic copepods in the genus Calanus that are prominent in high latitude oceans. C. finmarchicus dominates the mesozooplankton biomass across much of the coastal and deep North Atlantic Ocean. C. glacialis and the larger C. hyperboreus are among the most abundant planktonic copepods in the Arctic Ocean. Previous research showed that hatching success of C. finmarchicus eggs was severely inhibited by increased CO2 and lower pH in seawater, but only tested at an extreme level. Preliminary results in the investigator's laboratory indicate that hatching success of C. finmarchicus is substantially reduced at increased seawater CO2 concentrations corresponding to pH levels between 7.9 and 7.5. Predictions of likely decline of surface pH levels to 7.7-7.8 over the next century raise questions about impacts on Calanus population dynamics if these preliminary results are confirmed. C. finmarchicus, for example, is presently at the southern edge of its range in the Gulf of Maine. The combination of higher surface layer temperature and lower pH may inhibit reproductive success during the late summer/fall bloom, which the PI hypothesize is critical to sustain the overwintering stock in this region. The investigators will collect C. finmarchicus females from the Gulf of Maine and, with the assistance of Canadian colleagues, C. glacialis and C. hyperboreus females from the deep lower St. Lawrence Estuary. They will conduct laboratory experiments in which hatching success, development and growth of Calanus nauplius stages are measured in controls of natural seawater and at a series of treatments in which CO2 concentrations, pH and temperature are rigorously controlled to represent possible future states of the northern ocean. The investigators will measure present surface and deep pCO2 and pH across the Gulf of Maine, including its deep basins, during a research cruise. The study will evaluate the hypothesis that predicted levels of CO2 increase in the northern ocean will impact population dynamics of the Calanus species. Using the results from the research cruise and a recently developed 1-D, Individual-Based life cycle model, the PI will explore in detail scenarios of impact of higher temperature and lower surface and deep pH on population dynamics of C. finmarchicus in the Gulf of Maine.Broader impacts: The lipid-rich Calanus species are considered key intermediary links between primary production and higher trophic levels in North Atlantic and Arctic Ocean food webs. Impacts of higher surface temperature and lower pH on reproductive success may potentially lead to profound changes in energy transfer and structure of pelagic ecosystems in the northern oceans. In the Gulf of Maine, C. finmarchicus serves as primary prey for herring, sand lance, and mackerel, as well as the endangered northern right whale, warranting thorough evaluation of ocean acidification effects on its population dynamics. This research will provide cross discipline training to a graduate student and undergraduate student interns. Data will be deposited in a recognized data archiving center and results disseminated through presentations at scientific meetings and peer reviewed research articles. Public outreach will be planned as part of the Gulf of Maine Research Institute community activities, including learning opportunities associated with the Cohen Center for Interactive Learning directed at fifth and sixth graders in the state of Maine.