A numerical study of marine larval dispersal in the presence of an axial convergent front
A numerical study of marine larval dispersal in the presence of an axial convergent front
复制标题
存在轴向会聚锋面的海洋幼虫扩散的数值研究
DOI：
10.1016/j.ecss.2012.02.001
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发表时间：
2012
影响因子：
2.8
通讯作者：
L. Giménez
中科院分区：
文献类型：
--
作者：
P. Robins;S. Neill;L. Giménez
河口轴向辐合锋产生强烈的次级（跨河口）流，这对幼虫的扩散和定居很重要，并在本研究中显示有助于出生种群的河口滞留，从而促进生产。本文探讨了几种幼虫的迁徙策略，这些策略由压力、速度、盐度和太阳辐射等感官线索同步，与河口轴向辐合锋有关——这是一种在许多幼虫集中的沿海地区形成的重要循环机制；因此，这些结果对渔业管理具有启示意义。三维水动力模型应用于一个理想的渠道，参数化从观测康威河口的轴向收敛锋，英国。该模式模拟了锋面两侧横截面环流，这是由于纵向气流的横向切变与轴向盐度梯度的相互作用造成的。轴向地面辐合主要发生在涨潮期，而地面辐散则发生在退潮期。拉格朗日粒子跟踪模型随后使用一系列模拟潮汐和气候情景的速度来跟踪河口的幼虫。结果表明，轴向辐合锋有利于幼虫在河口滞留。特别是对经历潮汐流运输和潮汐迁移的幼虫，保留率提高。与潮汐同步的幼虫表现出最强的向陆地扩散，而模拟桡足类（潮汐和盐度线索的组合）在河口中部释放位置表现出“完全保留”。最后，幼虫的垂直迁移速度必须超过背景垂直速度，才能获得最大的滞留增强。
Estuarine axial convergent fronts generate strong secondary (cross-estuary) flows which can be important for larval dispersal and settlement, and have been shown in this research to aid estuarine retention of natal populations which will promote production. This paper explores several larval migratory strategies, synchronised by sensory cues such as pressure, velocity, salinity and solar radiation, in relation to an estuarine axial convergent front – an important circulatory mechanism that forms in many coastal regions where larvae are concentrated; hence these results have implications for fisheries management. A three-dimensional hydrodynamic model is applied to an idealised channel, parameterised from observations of a well documented axial convergent front in the Conwy Estuary, UK. The model simulates the bilateral cross-sectional circulation of the front, attributed to the interaction of lateral shear of the longitudinal currents with the axial salinity gradient. Axial surface convergence develops during the flood phase of the tide and (weaker) surface divergence during the ebb phase. Lagrangian Particle Tracking Models subsequently use velocities from a range of simulated tidal and climatic scenarios to track larvae in the estuary. The results show that axial convergent fronts aid estuarine retention of larvae. Specifically retention is enhanced for larvae that experience tidal stream transport and diel migration. Tidally-synchronised larvae exhibit the strongest landward dispersal while the modelled copepod (a combination of tidal and salinity cues) exhibits ‘full retention’ in the mid-estuary release location. Finally, the vertical migration speed of the larvae must exceed the background vertical velocities in order to get the greatest enhancement of retention.