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

我们对海洋种群在其部分或全部生命周期中如何受到海洋环流影响的理解目前仅限于大尺度环流和生物地理分布。在中尺度和小尺度的相互作用中，个体生物是最重要的，很难研究。本研究拟培育的垂直迁移拉格朗日漂虫将模拟野外十足类幼虫的小尺度垂直游动行为。根据实验室和对幼虫行为的实地观察安排的漂流者将被释放到螃蟹产卵的地方，以确定垂直迁移是否可以解释幼虫在河口滞留和最终到达成虫栖息地的原因。一艘较大的漂流船将携带ARGOS卫星发射机，跟踪从河口出口的螃蟹幼虫（切萨皮克湾的calinectes sapidus）的行为对运输的影响。一些海洋学模型预测，sapidus将被席卷出大西洋中部海湾，但在切萨皮克湾口50公里范围内仍有密集的种群，很明显，它们以巨藻和幼鱼的形式重新进入海湾。具有不同幼虫行为的漂流者程序将有助于解决这是由近地表幼虫的风驱动平流引起的，是大翅虫在底流中的被动运输，还是由垂直迁移到洪水潮汐流中加强的运输。对人类有相当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，但当它们接近成年时又回到海湾。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海湾的当地洋流如何共同维持海湾的种群数量。一种可以模仿幼虫行为的小型漂浮物正在被开发。这艘漂流船将携带一个卫星发射机，这样当它被洋流携带时，它的位置就可以被跟踪，它在水柱中的上下运动也可以被指定。漂船将被部署在成年蓝蟹产卵的地方。该漂流器将允许测试各种游泳行为，以确定哪种行为和水流的组合最真实地复制已知的幼虫分布，并导致维持切萨皮克湾的螃蟹数量。

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.