Retrospective Analysis of Dispersive and Retentive Behaviors of Young-of-the-Year Estuarine Fishes: Are Fish Otoliths Environmental Chronometers?

耳石微化学的最新进展为研究人员提供了在个体发育过程中追踪鱼类扩散的强大手段。该方法提供了有关鱼类扩散和运动的空间和时间信息。虽然利用耳石微量化学来重建海洋鱼类的环境历史已经得到了广泛的认可和报道，但基本的问题--鱼的耳石是否能起到‘忠实的环境计时器’的作用--在很大程度上还没有得到检验。这个项目测试了这样的假设，即耳石锶反映了河口和海洋鱼类个体发育早期盐度的变化。这一假说将在切萨皮克湾进行评估，因为这个系统包含环境梯度的极端范围。这项研究将严格检验耳石锶在实验室和野外环境中都能反映盐度的假设。该办法将分为三个层次，包括：1)对在恒定和波动的盐度和温度水平下饲养的个体进行耳石锶元素分析；2)对野生捕获和笼养个体的耳石锶进行元素分析，以及作为实地验证的一种手段；以及3)测量大范围(例如河口进出)和细尺度(河口运动内)切萨皮克湾年龄段河口鱼类幼体扩散的模式。将测量五种具有重要生态意义的河口物种的空间行为，它们的早期生活策略截然不同：美国鳗鱼、美国沙鱼、白鲈、斑点黄口鱼和斑点猪。S特别指出，锶/钙比值的准确度和精密度的具体估计将被用来评估耳石锶是否可以测量沿盐度梯度的扩散和年轻鱼类的后遗症空间历史。

Recent advances in otolith microchemistry have provided researchers with a powerful means of tracking fish dispersal throughout ontogeny. The approach provides both spatial and temporal information on fish dispersal and movement. While the use of otolith microchemistry for reconstructing environmental histories of marine fishes is well recognized and reported, the fundamental question, whether fish otoliths can function as `faithful environmental chronometers?` remains largely untested. This project tests the hypothesis that otolith strontium is reflective of changing salinities during the early ontogeny of estuarine and marine fishes. The hypothesis will be evaluated in the Chesapeake Bay because this system contains extreme ranges in environmental gradients. The research will rigorously test the hypothesis that otolith strontium is reflective of salinity in both laboratory and field environments. The approach will be three-tiered, including: 1) retrospective elemental assays of otolith strontium of individuals reared under constant and fluctuating schedules of salinity and temperature levels; 2) elemental assays of otolith strontium of wild caught and caged individuals, and the relation otolith strontium to ambient salinity as a means of field verification; and 3) measurement of broad scale (e.g. estuarine ingress and egress) and fine scale (within estuary movements) patterns of dispersal by young of the year (YOY) estuarine fishes in the Chesapeake Bay. Spatial behaviors will be measured for five ecologically important estuarine species with contrasting early life tactics: American eel Anguilla rostrata, American shad Alosa sapidissima, white perch Morone americana, spot Leiostomus xanthurus, and hogchoker Trinectes maculatus. S pecies specific estimates of accuracy and precision of the Sr:Ca ratio will be used to evaluate whether otolith strontium can measure dispersal along a salinity gradient and hindcast spatial histories of YOY fishes.