Predation by the Physonect Siphonophore Nanomia cara

在世界海洋中，了解浮游生物食物网如何运作对于预测有机循环的数量和速度至关重要。在浮游生物动力学的最不为人所知的调节者中，软？生活在水中深处(30？1000年)。最高?其中一组，即physonect siphonophores，通过捕食来控制下降，尤其难以量化，主要是因为这些多态动物非常脆弱，在用浮游生物网收集时很容易破碎。这次调查将使用载人潜水器(约翰逊？海吗?链接)和它所携带的工具来量化分布，丰度，行为，以及常见的，但研究很少的凝胶状卡拉纳米虫菌落的摄食。实地研究将在缅因湾地区（威尔金森盆地、乔治海岸和海洋学家峡谷）进行，在那里，这种水母的种群可能是浮游动物猎物种群的重要调节者。初步调查表明，N. cara有潜力消耗相当大一部分主要消费者的库存，特别是非？重现第四阶段？桡足动物Calanus finmarchicus的V。这种类calanoid物种的高死亡率可能对区域和流域尺度的渔业有害。对精心收集的菌落进行实验室调查，将确定在与原位条件（例如，温度和黑暗）相似的环境中消化和呼吸（=氧气消耗和氮排泄）的速率。这些数据与实地研究相结合，将为预测卡拉纳米虫的捕食影响提供基础。这项在个体和种群水平上对捕食者死亡率的研究将扩大美国在缅因湾/乔治海岸地区开展的GLOBEC项目的工作。这项研究的结果也可能对NOAA的COP乔治滩捕食研究有用，特别是如果N. cara捕食幼鱼。

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.