U.S.-GLOBEC: NWA Georges Bank: Effects of climate variability on Calanus dormancy patterns and population dynamics in the Northwest Atlantic

鳍足类是世界海洋中的关键生物，以高速率消耗初级和次级产品，是无脊椎动物、幼体和小型中上层鱼类、海鸟和海洋哺乳动物的猎物。许多生活在温带和高纬度地区的最丰富的桡足类动物，包括西北大西洋的Calanus finmarchicus，可以在它们的部分生命周期中休眠，这是一种发育受到抑制的状态。在休眠期间，桡足类逃离没有生产力的表层水域，在深水中生活几个月，之后它们出现并迁徙到水面，通常是在春季开花之前。从休眠中苏醒出来的桡足类的时间和丰度为活跃季节的种群增长设定了初始条件，可能对桡足类种群动态和幼鱼的摄食和生长都至关重要。同样，进入休眠的时间和由此导致的表层水域中猎物可获得性的减少，可能对表层浮游动物的种群动态很重要。对于Calanus finmarchicus或其他开放海洋桡足类物种来说，控制休眠开始和休眠的物理和生物因素是未知的。本项目旨在通过对西北大西洋Calanus finmarchicus休眠反应和相关环境条件的区域间比较和基于个体的模型(IBM)模拟来确定控制Calanus finmarchicus休眠开始和摆脱休眠的因素。这项研究验证了这样一种假设，即种群动态的地区间差异是由于不同的环境条件作用于具有相似休眠和生理速率对环境参数的反应的桡足类动物造成的。来自西北大西洋七个地区的数据集将被汇编，并与观测的生物物理数据集进行比较，以测试关于休眠控制机制的假设。IBM将在各个地区进行模拟，以检验改进后的休眠控制假说的合理性。IBM还将进行模拟，以测试模型对休眠和生理速率函数不确定性的敏感性，并评估种群对现实的地表和深海温度年际变化以及春季水华时间和幅度变化的反应。模拟的种群对气候变异性的反应将与太平洋微囊藻和马绍拉微囊藻正在进行的类似分析进行比较。拟议的研究结果对于理解影响一大类浮游生物季节性生产的基本过程将是重要的。这一知识对于理解气候变化对西北大西洋和东北太平洋食物网的整体营养影响至关重要。拟议的研究涉及一名硕士研究生和一名博士后的直接参与。这项研究代表了来自新汉普郡大学和NOAA太平洋渔业环境实验室(PFEL)的科学家之间的持续合作，其中包括与达尔豪西大学和加拿大渔业和海洋部实验室的科学家的合作。此外，这项提案的预期结果将适用于当前和拟议的GLOBEC桡足类种群建模工作。从这项工作中获得的信息将被证明对海洋哺乳动物(主要以C.finmarchicus为食的北方露脊鲸)以及乔治斯海岸和缅因湾的鳕鱼、鲱鱼和其他鱼类物种的管理以及对气候变化对这些物种的影响的了解是有价值的。

Calanoid copepods are key organisms throughout the world's oceans, consuming primary and secondary production at high rates, and serving as prey for invertebrates, larval and small pelagic fish, seabirds, and marine mammals. Many of the most abundant copepods in temperate and high latitudes, including Calanus finmarchicus in the Northwest Atlantic, can spend part of their life cycle in dormancy, a state of suppressed development. During dormancy, copepods escape unproductive surface waters and reside in deep water for several months, after which they emerge and migrate to the surface, usually prior to the spring bloom. The timing and abundance of copepods emerging from dormancy set initial conditions for population growth in the active season and is likely critical for both copepod population dynamics and for feeding and growth of larval fish. Similarly, the timing of entry into dormancy and consequent reduction of prey availability in surface waters, may be important to population dynamics of surface planktivores. The physical and biological factors that control onset of and emergence from dormancy are not known for Calanus finmarchicus or other open ocean copepod species.This project aims to identify the factors that control onset of and emergence from dormancy in Calanus finmarchicus in the Northwest Atlantic using both an inter-regional comparison of dormancy response and associated environmental conditions and individual-based model (IBM) simulations. The research tests the hypothesis that inter-regional differences in population dynamics are caused by different environmental conditions acting on copepods with similar dormancy and physiological rate responses to environmental parameters. Data sets from seven regions of the Northwest Atlantic will be compiled and compared to observational bio-physical data sets to test hypotheses about dormancy control mechanisms. IBM simulations will be run in individual regions to test the plausibility of the refined dormancy control hypotheses. IBM simulations will also be run to test the sensitivity of the model to uncertainty in dormancy and physiological rate functions, and to evaluate population responses to realistic interannual variability in surface and deepwater temperature and shifts in the timing and magnitude of the spring bloom. Modeled population responses to climate variability in C. finmarchicus will be compared to similar ongoing analyses in C. pacificus and C. marshallae. The results of the proposed research will be important for understanding basic processes that influence seasonal production of a major group of plankton. This knowledge is critical to understanding the overall trophic impact of climate change on food webs of both the Northwest Atlantic and Northeast Pacific.The proposed research involves the direct participation of one Master's level graduate student and one postdoctoral student. This research represents a continuing collaboration between scientists from the University of New Hampshire and NOAA's Pacific Fisheries Environmental Laboratory (PFEL), and it includes collaborations with scientists at Dalhousie University and Canadian Department of Fisheries and Oceans Laboratories. In addition, the results expected from this proposal will be applicable to current and proposed GLOBEC copepod population modeling efforts. The information gained from this work will prove valuable to management for marine mammals (northern right whale that feeds primarily on C. finmarchicus), as well as cod, herring and other fish species on Georges Bank and in the Gulf of Maine and for the understanding of impacts of climate change on these species.