Collaborative Research: US GLOBEC: Predation Impacts on Target Specie: Roles of Frontal Proceses and Small Predator Species

GLOBEC乔治斯银行项目正在寻求了解决定四个目标物种--鳕鱼和黑线鳕幼体及其主要饲料猎物--尺足类Calanusfinmarchicus和Pseudocalanus spp的种群动态的物理和生物过程。这些过程的核心是无脊椎动物和鱼类捕食者对这四个物种的捕食，本研究的目的是描述和量化这一死亡来源。该方法结合了来自持续的大范围调查的乔治斯滩捕食者和目标猎物物种的丰度和共生情况的信息，以及主要捕食者物种的取食特性和比率的新数据。在第一阶段和第二阶段，Madin博士、Sullivan博士和Bolens博士使用肠道内容物分析(通过显微镜和免疫分析)和喂养实验(船上和实验室，在小容器和系膜中)来获得喂养数据。前两个阶段的实地抽样侧重于分层效应(1995年)以及水和生物的来源、保留和损失(1997年)等主题。在第三阶段，他们将(在1999年)把实地工作的重点放在关于锋面区域对目标物种及其捕食者的运输、聚集和相互作用的影响的问题上。传统的采样将辅以视频系统，以检测大型胶状捕食者。对浮游生物群落动力学研究的重大新贡献将是确定杂食性桡足类在限制草食动物产量中的作用，以及对湍流在控制胶状捕食者捕食率中的作用的实验研究。乔治斯滩的物理和水文环境为目标物种及其捕食者的生物相互作用奠定了基础。河岸的水深测量和其上及其周围的环流模式在其南北边界上以及沿其60米等深线，在混合良好的中央海脊和季节性分层的南侧之间形成了锋区。最后一个区域，潮汐混合前锋，划分了两个在水文和生物方面非常不同的区域。这些研究人员将在1999年的两次巡航中在这条战线上工作，以确定沿锋面和跨锋面的猎物和捕食者的分布和丰度，锋面动态对聚集和相互作用的影响，以及生物从一边到另一边的交换。峰顶和侧翼区域是他们在以前的过程研究中集中努力的地方，也是目标物种与其主要捕食者之间出现严重重叠的地方。与锋面相关的湍流、辐合和交换可能会对不同取食生物的捕食者产生不同的影响。长期了解乔治斯银行系统的关键是建立全面的物理-生物模型。这项研究应该对这些模型做出重大贡献，提供特定于季节、地点、物种以及主要捕食者、捕食者阶段和猎物密度的捕食死亡率数据。

9806465MadinThe GLOBEC Georges Bank program is seeking to understand the physical and biological processes which determine the population dynamics of four target species -- larval cod and haddock, and their main forage prey, the copepods Calanusfinmarchicus and Pseudocalanus spp. Central among these processes is predation by invertebrate and fish predators on these four species, and the objective of this study is the description and quantification of this source of mortality.The approach combines information on the abundance and co-occurrence of predators and target prey species on Georges Bank, derived from the continuing Broad Scale Survey, with new data on feeding specificity and rates of the principal predator species. During Phases I and II, Drs. Madin, Sullivan and Bollens have used both gut-contents analysis (by microscopy and with immuno-assays) and feeding experiments (shipboard and laboratory, in small containers and mesocosms) to obtain feeding data. The field sampling during the first two Phases focused on the themes of stratification effects (1995) and source, retention and loss of water and organisms (1997). In Phase III they will direct field efforts (in 1999) to questions concerning effects of frontal regions on the transport, aggregation and interaction of target species and their predators. Conventional sampling will be supplemented with a video system to detect large gelatinous predators. Significant new contributions to the study of plankton community dynamics will be identification of the role of omnivorous copepods in limiting production of herbivores, and experimental studies of the role of turbulence in controlling predation rates of gelatinous predators.The physical and hydrographic environment of Georges Bank sets the stage for the biological interplay of target species and their predators. The bathymetry of the Bank and the pattern of circulation on and around it create frontal regions on its north and south boundaries, and along its 60 m isobath, between the well-mixed central Crest and the seasonally stratified southern Flank. This last region, the tidal mixing front, divides two areas which are very different in terms of hydrography and biology. These researchers will work at this front on two cruises in 1999, to determine the distribution and abundance of prey and predators along and across the front, the effect of frontal dynamics on aggregation and interaction, and the exchange of organisms from one side to the other. The Crest and Flank regions are where they have concentrated efforts in previous process studies, and where there appears to be a critical overlap in occurrence between target species and their main predators. Turbulence, convergence and exchange associated with the front may have different effects on predators with different feeding biologies. The key to long-term understanding of the Georges Bank system is development of comprehensive physical-biological models. This study should make a major contribution to these models with data on predation mortality which is specific to season, location, species, and for principal predators, stage and density of the prey.