Predation by the Physonect Siphonophore Nanomia cara

在世界海洋中，了解浮游食物网是如何运作的，对于预测有机循环的数量和速度至关重要。对浮游生物动态最不了解的调节者之一是生活在中水深处(30？1000英寸)的软体浮游动物。体型管水母类通过捕食进行自上而下的控制特别困难，主要是因为这些多态的动物极其脆弱，当用浮游生物网捕获时很容易破碎。这项调查将使用载人潜水器(约翰逊？海？林克)和它携带的工具来量化常见的、但研究较少的、胶状的纳米虫群体的分布、丰度、行为和取食。将在缅因湾地区(威尔金森盆地、乔治斯浅滩和海洋学家峡谷)进行实地研究，在那里，这种体型管水母Cara的种群可能是浮游动物猎物种群的重要调节因素。初步调查表明，N.Cara有可能消耗相当一部分初级消费者的常备种群，特别是桡足类Calanus finmarchicus的非繁殖阶段IV？V。这种金枪鱼物种的高死亡率可能对区域和流域规模的渔业不利。对仔细收集的菌落进行实验室调查，将确定在类似于现场条件(如温度和黑暗)的环境中的消化和呼吸速率(=氧气消耗和氮气排泄)。这些数据与实地研究相结合，将为预测Nanomia Cara的捕食影响提供基础。这项关于个体和种群捕食死亡率的研究将扩大美国在缅因湾/乔治斯海岸地区的GLOBEC计划中开展的工作。这项研究的结果也可能对NOAA的COP Georges Bank捕食研究有用，特别是如果N.Cara捕食幼鱼的话。

In the world's oceans, understanding how planktonic food webs operate is crucial to predicting the amounts and rates of organic cycling. Among the least understood regulators of plankton dynamics are the soft?bodied zooplankton that reside at midwater depths (30?1000 in). Top?down control via predation by one group, the physonect siphonophores, has been especially difficult to quantify, principally because these polymorphic animals are extremely fragile and readily fragment when collected with plankton nets. This investigation will use a manned submersible (Johnson?Sea?Link) and the tools it carries to quantify the distribution, abundance, behavior, and feeding of the common, but poorly studied, gelatinous colonies of Nanomia cara. Field studies will be conducted in the Gulf of Maine region (Wilkinson Basin, Georges Bank and Oceanographer Canyon) where populations of this physonect siphonophore Nanomia cara are likely to be important regulators of zooplankton prey stocks. Preliminary investigations have indicated that N. cara has the potential to consume a significant portion of the standing stocks of primary consumers, specifically the non?reproducing stages IV?V of the copepod Calanus finmarchicus. High mortality rates of this calanoid species can be detrimental to fisheries on regional and basin scales. Laboratory investigations of carefully collected colonies will determine rates of digestion and respiration (=oxygen consumption and nitrogen excretion) in environments that are similar to in situ conditions (e.g., temperature and darkness). These data in conjunction with field studies will provide a basis for predicting the predatory impact of Nanomia cara. This study of predation mortality at individual and population levels will broaden the work undertaken in the U.S. GLOBEC program in the Gulf of Maine/Georges Bank regime. Results from this research are also likely to be useful for NOAA's COP Georges Bank Predation study, especially if N. cara preys on larval fishes.