Measuring Changes in Nutritional Status, Growth Rate, and Reproductive Condition of Deposit Feeders in Response to Sediment Transport - Methods

泥沙输运是一个普遍存在的海洋学过程。理论模型和有限的实验室研究表明，沉积物运输影响提供给底栖沉积物捕食者的有机物的数量和质量，但影响的幅度和方向（即积极或消极）在现场基本上是未知的。如果泥沙运输能够增加食物资源，那么沉积物捕食者的反应可能表现为个体生长速度的提高、能量储存产物的积累或繁殖产量的增加。相反，如果沉积物运输对食物资源产生不利影响，则应看到这些特性的负响应。这些反应可能单独发生，也可能以各种组合方式发生。需要在野外收集的动物中测量这些参数的方法，以便为沉积物运输对沉积物食用者能量学的影响以及最终对种群动态的影响的假设提供现实的测试。为了开始朝这个方向发展，dr。Taghon和Prahl将确定几种物种（包括棘皮动物、多毛动物和软体动物）的营养状况、生长速度和生殖状况在不同的实验室喂养制度下的变化。他们将测量3个特性随时间的变化，以评估它们在跟踪沉积物运输中对沉积物的反应中的用途：脂质储存的积累或使用（营养状况指数），RNA:DNA比率（生长速度指数）和生殖状况。

Sediment transport is a ubiquitous oceanographic process. Theoretical models and limited laboratory studies indicate that sediment transport influences the quantity and quality of organic matter supplied to benthic deposit feeders, but the magnitudes and directions of the influences (i.e., positive or negative) in the field are essentially unknown. If sediment transport acts to enhance food resources, the response by deposit feeders might be manifested as increased individual growth rates, by accumulation of energy storage products, or by increased reproductive output. Conversely, negative responses in these properties should be seen if sediment transport adversely affects food resources. Such responses might occur singly or in various combinations. Methods to measure these parameters in animals collected from the field are needed in order to provide realistic tests of hypotheses about the effects of sediment transport on the energetics of deposit feeders and ultimately, on population dynamics. To begin moving in this direction, Drs. Taghon and Prahl will determine how nutritional status, growth rate, and reproductive condition of several species (including echinoderms, polychaetes, and molluscs) vary under different laboratory feeding regimes. They will measure changes over time in 3 properties to evaluate their use in tracking the response of deposit feeders to sediment transport: the accumulation or use of lipid stores (index of nutritional status), RNA:DNA ratios (index of growth rate), and reproductive condition.