Spatial and Temporal Characteristics of Entrainment and Transport of Horseshoe Crab (Limulus polyphemus) Eggs in the Swash Zone of Estuarine Beaches

鱼类和无脊椎动物卵的携带、扩散和沉积的位置和时间对许多生物的摄食行为和生命周期具有重要影响。一个关键的例子是马蹄蟹卵作为西半球海鸟的营养来源的重要性，这些海鸟从南美洲迁徙到北极数千公里。本项目将研究SWASH(波浪上冲和反冲)过程在调节由于捕捞马蹄蟹和改变河口海滩栖息地而受到压力的马蹄蟹和迁徙滨鸟之间的关系中所起的作用。这些强调强调了理解维持马蹄蟹和滨鸟之间联系的物理过程的重要性。卵子在沼泽中的运输机制尚不清楚，现有的沉积物运输模型是为暴露在海洋环境中的海滩设计的，而不是在河口。这项研究将确定SWASH中解释沉积物和鸡蛋夹带和运输的关键过程，并使用新泽西州特拉华湾两个地点的现场数据来测试SWASH输送模型的适用性。将收集以下数据：1)水流速度、深度、宽度和持续时间，2)在前滨注入示踪剂的泥沙和鸡蛋的夹带，在仅由泥沙和破碎器和泥水共同作用的位置挖掘和输送泥沙和鸡蛋，以及3)使用全负荷泥沙捕集器在泥沙和卵子中输送的数量。这项研究将确定泥沙和鸡蛋的冲刷参数与总负荷之间的统计显著关系，并将利用跨岸水流速度和泥沙负荷数据来检验和校准输运模型。这项研究的结果将填补我们对高潮汐环境下河口海滩冲刷过程的理解的空白。冲浪区是对这些海滩上的风暴作出反应的最高输移率的地方，研究结果将为侵蚀和淤积的循环提供更好的过程解释。随着河口更多的沙质海岸被人工滋养以保护人类住区，除了提供海岸保护和娱乐空间的传统目的外，越来越需要海滩滋养设计标准来提高生物生产力和生态系统功能。随着对沼泽区鸡蛋运输知识的增加，候鸟种群的种群适宜性和基于营养来源的潜在危害模型将得到加强。该项目还为两名本科生提供了密集的实地和实验室体验，他们将有机会与自然地理和生物学的教师一起进行实地实验，从而获得独特的学习经验，将这两个领域的知识整合到关键资源问题的研究中。

The location and timing of entrainment, dispersal and deposition of eggs of fish and invertebrates have important implications for the feeding behavior and life cycles of many organisms. A key example is found in the significance of horseshoe crab eggs as a nutritional source for western hemisphere shorebirds that migrate thousands of kilometers from South America to the Arctic. This project will examine the role of swash (wave uprush and backwash) processes in mediating the relationship between horseshoe crabs and migratory shorebirds that are both under stress due to horseshoe crab harvesting and alteration of estuarine beach habitat. These stresses place increased importance on understanding the physical processes that maintain the link between horseshoe crabs and shorebirds. The mechanics of egg transport in the swash are not known, and existing models of sediment transport are designed for beaches in exposed ocean environments, not in estuaries. This study will identify key processes in the swash that explain sediment and egg entrainment and transport and test the applicability of swash transport models using field data from two sites in Delaware Bay, New Jersey. Data will be gathered on: 1) flow velocity, depth, width and duration of the swash, 2) entrainment of sediment and eggs using tracer injected in the foreshore in locations where exhumation and transport is due to both the swash and breakers and swash alone, and 3) amount of sediment and eggs transported in the swash using total load sediment traps. Statistically significant relationships between swash parameters and total load for sediment and eggs will be determined, and data on cross-shore flow velocities and sediment load will be used to test and calibrate a transport model.The results of this study will fill the gap in our understanding of swash processes on estuarine beaches in high micro-tidal environments. The swash zone is where the highest rates of transport occur in response to storms on these beaches and study results will provide better a better process explanation for cycles of erosion and accretion. As more sandy shores in estuaries are artificially nourished to provide protection to human settlements, there is an increasing need for beach nourishment design criteria that enhance biological productivity and ecosystem function in addition to the traditional purposes of providing shore protection and recreation space. Population fitness of migratory bird populations and models of potential endangerment based on nutritional sources will be enhanced from increased knowledge of egg transport in the swash zone. The project also provides an intensive field and laboratory experience for two undergraduate students who will have the opportunity to work on a field experiment with faculty from both physical geography and biology and thus have a unique learning experience that will integrate these two fields of knowledge to the study of a critical resource problem.