Adaptive Significance of the Formation of Multi-Species Fish Spawning Aggregations near Submerged Capes
Adaptive Significance of the Formation of Multi-Species Fish Spawning Aggregations near Submerged Capes
复制标题
水下岬附近多物种鱼类产卵聚集体形成的适应性意义
作者：
M. Karnauskas;L. Chérubin;Claire B Paris
背景许多鱼类在独特的地貌特征如水下海角或“海角”产卵，广泛使用这些地点产卵必然意味着一些进化优势。在这些海角产卵被认为会导致卵的快速离岸运输，从而减少捕食水平，并促进分散到合适的栖息地。方法/主要结果要测试这个“离礁运输”的假设，我们使用的流体动力学模型，并探讨地形对电流的影响，在水下的海角产卵发生，并在类似的海角产卵不发生，沿着中美洲堡礁。在这项研究中建模的所有海角产生涡流脱落制度，但特定的涡流属性产卵和非产卵地点之间的差异。产卵场的涡旋明显强于非产卵场，上升流和锋面是涡旋形成过程的产物。锋面区，特别是在边缘的涡流附近的货架，可能会保留幼虫和营养物质。产卵场漩涡的直径和寿命也更可预测。在产卵和控制网站发布的被动颗粒分散从释放网站以相似的速度，但产卵网站的颗粒更高度聚集在他们的分布比那些从控制网站，并保持更接近海岸在任何时候。结论/意义我们的研究结果与以前的假设相矛盾，即海角产卵导致高蛋分散由于离岸运输，他们是有吸引力的产卵，由于高，可变电流。相反，我们表明，目前的制度在产卵地点是更可预测的，集中的鸡蛋，并保持幼虫更接近海岸。这些属性将通过年复一年地保持相对相似的招募模式而赋予进化优势。
Background Many fishes are known to spawn at distinct geomorphological features such as submerged capes or “promontories,” and the widespread use of these sites for spawning must imply some evolutionary advantage. Spawning at these capes is thought to result in rapid offshore transport of eggs, thereby reducing predation levels and facilitating dispersal to areas of suitable habitat. Methodology/Principal Findings To test this “off-reef transport” hypothesis, we use a hydrodynamic model and explore the effects of topography on currents at submerged capes where spawning occurs and at similar capes where spawning does not occur, along the Mesoamerican Barrier Reef. All capes modeled in this study produced eddy-shedding regimes, but specific eddy attributes differed between spawning and non-spawning sites. Eddies at spawning sites were significantly stronger than those at non-spawning sites, and upwelling and fronts were the products of the eddy formation process. Frontal zones, present particularly at the edges of eddies near the shelf, may serve to retain larvae and nutrients. Spawning site eddies were also more predictable in terms of diameter and longevity. Passive particles released at spawning and control sites were dispersed from the release site at similar rates, but particles from spawning sites were more highly aggregated in their distributions than those from control sites, and remained closer to shore at all times. Conclusions/Significance Our findings contradict previous hypotheses that cape spawning leads to high egg dispersion due to offshore transport, and that they are attractive for spawning due to high, variable currents. Rather, we show that current regimes at spawning sites are more predictable, concentrate the eggs, and keep larvae closer to shore. These attributes would confer evolutionary advantages by maintaining relatively similar recruitment patterns year after year.