Physical and Physiological Growth Contraints of Key, North Sea Gelatinous Zooplankton

由于缺乏检测生长生理的对照实验，许多海洋系统中胶状浮游动物的丰度正在增加，其营养动力学后果尚不清楚。这项拟议的研究探索了北海四种关键的胶状捕食者的生物能量学(代谢：合成代谢和分解代谢)：金枪鱼、毛囊蓝藻、侧耳和莱氏沼虾。在水华条件下，这两个水母和两个鞭毛虫物种都可以自上而下地控制浮游动物资源，限制能量流向其他初级消费者。此外，它们还可以直接捕食主要海洋鱼类物种的早期幼体。这些胶状捕食者的捕食压力在水动力汇聚区特别强烈，例如在北海的锋面：滋养动力“热点”。这项建议中计划的研究应该能够量化这些主要捕食者的能量和营养需求，并测量和模拟食物数量和食物质量(以元素比率的变化表示)对四种胶状浮游动物生长和繁殖的交互影响。这项研究扩展了先前的结果，这些结果表明，与其他次级消费者(例如幼鱼)相比，食物的营养化学计量比的变化如何影响水母的生产力方面存在根本差异。我们的实验测试了关于海洋系统中关键捕食者的生态化学计量和资源有限增长的基本假设。我们从生理实验中获得的知识将被用来建立动态的能量平衡和胶状浮游动物觅食和生长的基于个体的模型(IBM)，据我们所知，这是第一次在这样的模型中不仅考虑能量，而且考虑食物质量。如果我们希望了解水母的生长动态和资源限制，这些实验室和模拟活动是必不可少的，也是获得这些捕食者在北海和其他地方的营养动态影响的可靠预测的必要条件。

The abundance of gelatinous zooplankters is increasing in many marine systems with unknown trophodynamic consequences due to a lack of controlled experiments examining growth physiology. This proposed research explores the bioenergetics (metabolism: anabolism and catabolism) of four, key gelatinous predators in the North Sea: Aurelia aurita, Cyanea capillata, Pleurobrachia pileus and Mnemiopsis leidyi. During bloom conditions, each of these two scyphozoan and two ctenophore species can exert top-down control on zooplankton resources, limiting the flow of energy to other primary consumers. Moreover, they can directly prey upon early larval stages of key marine fish species. Predation pressure by these gelatinous predators is particularly intense at hydrodynamic convergence zones such as fronts: trophodynamic “hot spots” in the North Sea. The research planned in this proposal should allow the quantification of energetic and nutrient demands of these key predators, and measure and model the interactive effects of food quantity and food quality (expressed as changes in elemental ratios) on growth and reproduction in the four gelatinous zooplankters. The research expands upon previous results suggesting fundamental differences in how changes in nutrient stoichiometry of food affect the productivity of jellyfish compared to other secondary consumers (e.g., larval fish). Our experiments test fundamental hypotheses regarding ecological stoichiometry and resource-limited growth in key predators in marine systems. Knowledge gained from our physiological experiments will be used to create dynamic energy budgets and individual-based models (IBMs) of foraging and growth for gelatinous zooplankton, and it is to our knowledge the first time that not only energy, but also food quality is taken into account in such models. These laboratory and modelling activities are essential if we hope to understand growth dynamics and resource limitation in jellyfish and are a perquisite for gaining robust projections of the trophodynamic impacts of these predators in the North Sea and elsewhere.