Evaluation of Larval Transport Models using a Programmable, Vertically Migrating 'Zooplankton Mimic'

我们对海洋种群如何在其部分或全部生命周期中受到海洋环流的影响的理解，目前仅限于大规模的环流和生物地理分布。中尺度和小尺度的相互作用是很难研究的，其中个体有机体是首要的。本研究将开发的垂直迁徙拉格朗日漂移器将模拟十足类幼虫在野外的小尺度垂直游泳行为。根据对幼虫行为的实验室和野外观察，将在螃蟹产卵的地方释放漂移器，以确定垂直迁移是否可以解释幼虫在河口的滞留和最终到达成年栖息地。一个较大的漂流者携带着Argos卫星发射器，将跟踪行为对从切萨皮克湾(切萨皮克湾的Callinectes senidus)出口的蟹幼虫运输的影响。一些海洋模型预测，蓝鳍金枪鱼将被冲出大西洋中部海湾，但密集的种群仍在切萨皮克湾入海口50公里范围内，显然是以巨型幼体和幼鱼的形式重新进入海湾。具有不同幼虫行为的漂移器将有助于解决这是由近地表幼虫的风致平流、底流中大眼目动物的被动迁移还是由于垂直迁移到洪水潮流中而增强的迁移造成的。对人类有相当大价值的贝类资源之一是切萨皮克湾和美国东南部其他河口的蓝蟹。对幼虫分布的研究表明，它们在生命周期的一部分离开切萨皮克湾，但在接近成年期时重新进入该湾。目前尚不清楚它们在水柱中的位置、它们在水柱中上下移动的能力，以及海湾和大西洋中部的当地水流是如何结合在一起来维持海湾的种群数量的。一种可以模仿幼虫行为的小型漂浮器正在开发中。漂流者将携带一个卫星发射器，这样当它被水流携带时，它的位置就可以被跟踪，并可以指定它在水柱中的上下移动。漂流者将部署在成年蓝蟹产卵的地方。漂流者将允许测试各种游泳行为，以确定哪种行为和水流的组合(S)最真实地复制了已知的幼虫分布，并导致切萨皮克湾螃蟹种群的维持。

Our understanding of how populations in the sea are affected by the ocean circulation to which they are subject during part or all of their life cycle is restricted at the moment to large scale circulation and biogeographic distributions. Mesoscale and small scale interactions, where the individual organism is of primary importance, are difficult to study. The vertically migrating Lagrangian drifter to be developed in this study will emulate the small-scale vertical swimming behavior of decapod larvae in the field. Drifters programmed according to laboratory and field observations of larval behavior will be released where crabs are spawning to determine if vertical migration can account for retention of larvae in estuaries and ultimate arrival at adult habitats. A larger drifter, carrying an ARGOS satellite transmitter, will track effects of behavior on transport of crab larvae exported from an esutary (Callinectes sapidus in Chesapeake Bay). Some oceanographic models predict that C. sapidus will be swept out of the mid-Atlantic Bight, but dense populations remain within 50km of the mouth of Chesapeake Bay,k apparently re-entering the Bay as megaloae and juveniles. Drifters programmed with alternative larval behaviors will help resolve whether this is caused by wind-driven advection of near- surface larvae, passive transport of megalopae in bottom currents, or transport enhanced by vertical migration into flood tidal currents. %%% One of the shellfish resources of considerable value to man is the blue crab of Chesapeake Bay and other estuaries of the southeastern United States. Studies of the distribution of the larvae have shown that they exit Chesapeake Bay during part of their life cycle, but then re-enter the Bay when they near adulthood. It is not clear how their position in the water column, their ability to move up and down in the water column, and the local currents in the Bay and mid-Atlantic Bight combine to maintain the populations in the Bay. A small drifter that can mimic larval behavior is being developed. The drifter will carry a satellite transmitter so that its position can be tracked as it is carried by the currents, and its movement up and down in the water column can be specified. The drifter will be deployed where the adult blue crabs spawn. The drifter will allow various swimming behaviors to be tested to determine which combination(s) of behavior and currents most realistically copy known larval distributions and result in maintenance of the crab population in the Chesapeake Bay.