Complex Predator-Prey Interactions in Marine Soft-Bottom Communities: Crabs, Clams and Patch Dynamics

这项研究的总体目标是定量地确定海洋软底群落中捕食-被捕食动态的相互作用的调节因素和潜在的机制。研究人员拥有广泛的背景知识以及创新的超声波生物遥测技术，可以在切萨皮克湾的一个小河口(罗德河)检查捕食者-猎物复合体。研究人员将测量捕食者行为的组成部分，这些组成部分会导致功能和聚合反应的变化。捕食者-猎物复合体包括大型蓝蟹(Callinectes Sapidus)，它们以两种常见的非动物群贝类(Macoma balthica和Mya arenaria)为食，以及相互残食的小蓝蟹。底层鱼也是大量的捕食者，广泛以文蛤虹吸和其他生活在沉积物中的底栖无脊椎动物为食，但不是以大的完整的文蛤为食。早期的工作集中在猎物种类、沉积物类型和猎物密度对猎物遇到激烈捕食时的持久性的交互影响，重点是蓝蟹以文蛤为食的功能反应。生物遥测技术已经被用来确定捕食者行为和关键猎物斑块之间移动的变化范围。因此，这些研究集中在蓝蟹与猎物斑块的聚集反应，它联系着这个捕食者-猎物系统的调节因素、潜在机制和由此产生的动力学。本研究将：1)确定控制主要捕食者(大青蟹)聚集反应的交互因素(猎物种类、猎物密度和捕食者密度)；2)确定控制两种交替猎物(文蛤和小蟹)捕食率的交互因素(猎物密度和分布、栖息地避难所和捕食者密度)；3)研究大型青蟹聚集在捕食区以及在小蟹和文蛤之间转换的行为/生理机制。

The overall goal of this research is to determine quantitatively, the interactive regulatory factors and underlying mechanisms of predator-prey dynamics in a marine soft-bottom community. The researchers have extensive background knowledge as well as an innovative ultrasonic biotelemetry techniques to examine the predator-prey complex in a small sub-estuary (the Rhode River) of Chesapeake Bay. The researchers will measure the components of predator behavior which lead to changes in the functional and aggregative responses. The predator-prey complex includes large blue crabs (Callinectes sapidus) which feed on two common species of infaunal clams (Macoma balthica and Mya arenaria) as well as cannibalizing small blue crabs. Demersal fish are also abundant predators which feed extensively on clam siphons and other benthic invertebrates which live in the sediments, but not on large whole clams. Earlier work focused on the interactive effects of prey species, sediment type, and prey density on the persistence of prey encountering intense predation, with emphasis on the functional response of blue crabs foraging on clams. Biotelemetry has been used to determine the scales of variation in predator behavior and movement between key prey patches. Thus, these investigatins focus on the blue crab's aggregative response with prey patches, which links the regulatory factors, underlying mechanisms, and resulting dynamics of this predator-prey system. This research will: 1) determine the interactive factors (prey species, prey density, and predator density) regulating the aggregative response of the main predator (large blue crabs); 2) determine the interactive factors (density and distribution of prey, habitat refugia, and predator density) regulating predation rates upon two alternate prey (clams and small crabs); and 3) investigate the behavioral/physiological mechanisms of large blue crabs aggregating in prey patches and switching between small crabs and clams.