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首页> 外文期刊>Estuarine Coastal and Shelf Science >Delivery and movement of horseshoe crab eggs (Limulus polyphemus) in the breaking waves and swash uprush of an estuarine foreshore
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Delivery and movement of horseshoe crab eggs (Limulus polyphemus) in the breaking waves and swash uprush of an estuarine foreshore

机译：马蹄蟹卵（Li卵）在海浪前滩的冲浪和冲刷隆升中的输送和运动

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Knowledge of conditions for entrainment of eggs and larvae from beach spawning sites is critical in determining the likelihood that these food sources will be delivered to shorebirds. The exhumation of horseshoe crab eggs buried within the beach foreshore is a function of changes in wave and current velocities over a tidal cycle. This field study was conducted to evaluate the temporal constraints to egg release at two different locations across the foreshore of a sandy estuarine beach in Delaware Bay, New Jersey. Wind, wave, current characteristics, beach change and eggs in transport were sampled over two tidal cycles. Egg counts were determined using four colors of dyed-egg tracers placed as point sources 5 and 10 m bayward of the expected upper limit of swash. Tracer recovery varied from 1% to 18% of the tracer eggs buried. Wave heights were relatively low (instrumented H_s = 0.09-0.17 m) but with long periods (5.6-8.8 s). Results reveal that egg release is discontinuous and occurs in pulses when the swash and breakers migrate across the injection points on the rising tide and when the breakers migrate past the injection points during the falling tide. A lack of tracer at the upper (5 m) injection point after early stages of high tide is likely due to the maximum disturbance depth being achieved early, leaving no eggs within the swash boundary layer. Peaks in recovery of tracer initially buried at the lower (10 m) location after the breakers migrated up the foreshore well past the injection location are likely from eggs deposited in the wrack on the upper beach or reburied in the sediment near the upper limit of swash and remobilized by high swash uprushes. These results using point sources of tracer eggs suggest that the contribution of eggs from within the beach matrix is temporally variable across the foreshore. Most eggs are released during rising tide, but additional eggs can be released during falling tide if the depth of activation of the bed is greater than on the rise due to net erosion or change to higher wave-energy conditions. Successful shorebird foraging at other times in the falling tide appears due to transport of eggs released earlier in the tidal cycle and delivered alongshore and not due to eggs exhumed in-situ at that time.
机译：了解从海滩产卵场带走卵和幼虫的条件，对于确定将这些食物来源输送给水鸟的可能性至关重要。埋在海滩前滨的horse蟹卵的发掘是潮汐周期内波浪和流速变化的函数。进行了这项野外研究，以评估新泽西州特拉华湾沙质河口海滩前岸两个不同地点卵子释放的时间限制。在两个潮汐周期中对风，浪，当前特征，海滩变化和运输中的卵进行了采样。使用四种颜色的染卵示踪剂确定鸡蛋计数，这些示踪物被放置在预期的斜率上限的5和10 m处，作为点源。示踪剂的回收率介于埋藏的示踪卵的1％到18％之间。波高相对较低（测量H_s = 0.09-0.17 m），但周期较长（5.6-8.8 s）。结果显示，当斜盘和破碎锤在涨潮时跨过注入点迁移时，以及破碎锤在下降潮汐时越过注入点迁移时，卵的释放是不连续的，并且以脉冲形式发生。在涨潮的早期阶段之后，在上部注入点（5 m）缺少示踪剂，这可能是由于尽早达到最大扰动深度，在斜流边界层内没有卵。在破碎锤向着注入点上方的前海沿岸迁移之后，最初埋藏在下部（10 m）位置的示踪剂的恢复峰值可能来自沉积在上部海滩残骸中的卵或重新埋藏在冲刷上限附近的沉积物中并因高冲积潮而复员。使用示踪卵的点源的这些结果表明，海滩基质中卵的贡献在整个前滨随时间变化。大多数蛋在涨潮时被释放，但是如果由于净侵蚀或改变波能条件而使床的激活深度大于上升时，则在落潮时可以释放更多的蛋。在落潮时的其他时间，成功的shore鸟觅食是由于潮汐周期中较早释放并沿岸运送的卵的运输所致，而不是由于当时就地发掘出卵而引起的。

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