Grazing and Carbon Cycling by the Epipelagic Crustacean Zooplankton of the Arabian Sea

史密斯9310599在阿拉伯海观测到了地球上任何地方对海洋性质的一些最强烈的大气强迫，在那里，季节性逆转的季风风驱动着快速流动的垂直扩展的洋流，复杂的涡流，大范围的开阔海洋上升流，沿海上升流和明显的混合层加深。这一地区的生产周期是季节性波动。在西南季风季(6-9月包括在内)，由于大风不仅导致营养丰富的深水抬升，而且将风尘带到这个热带海洋的表层，初级生产力最大。在东北季风期间(10-11月包括在内)和季风间期，初级生产力显著降低。在西南季风季，浮游动物的生物量和次生生产力也有所增加。根据对索马里的早期研究，假设阿曼近海表层浮游动物的物种组成从一个季风季到另一个季风季发生重大变化，西南季风期间的生物量主要由快速增长的中大型浮游动物食草动物，如Calanoides和Eucalanus等主导。在其他季节，这些食草动物在地下深处的数量减少。相对较大、生长迅速的食草动物的季节性出现在很大程度上决定了浮游动物群落对西南季风(上升流)期间在阿拉伯海发展的浮游植物群落的放牧影响。放牧影响反过来调节了碳向深度的通量，是该地区碳沉积时空格局的一个重要因素。在阿曼附近的阿拉伯海，可以结合调查放牧对阿拉伯海中部常年营养不良的碳通量的贡献，来研究由上升流区放牧群落的大的季节性变化所驱动的碳通量。氧浓度在大约150米处的陡峭梯度将大多数上层食草动物限制在这个深度以上的表层。将使用多重开闭网(MOCNESS)来研究上层中大型浮游动物食草动物的作用，以确定分布和丰度，特别注意氧-亚氧界面和孵化实验以确定摄食、粪便颗粒产量和生长速度。

Smith 9310599 Some of the strongest atomspheric forcing of oceanic properties anywhere on our planet is observed in the Arabian Sea where seasonally reversing monsoon winds drive fast- flowing, vertically extensive currents, complex eddy fields, broad-scale, open ocean upwelling, coastal upwelling and pronounced mixed-layer deepening. Cycles of production in this region are seasonal oscillations. During the southwest monsoon season (June-September inclusive), primary productivity is maximal owing to strong winds which not only cause the uplift of deep water rich in nutrient, but also deliver aeolian dust to the surface layer of this tropical ocean. During the northeast monsoon (October-November inclusive) and intermonsoon periods, primary productivity is markedly reduced. Biomass of zooplankton and secondary productivity are also elevated during the southwest monsoon season. Based upon earlier studies off Somalia, the epipelagic zooplankton off Oman is hypothesized to undergo significant changes in species composition from one monsoon season to another, with biomass during the southwest monsoon dominated by rapidly growing meso- and macrozooplanktonic grazers such as Calanoides and Eucalanus. These grazers exist in reduced abundance at subsurface depths during other seasons. The seasonal appearance of relatively large, fast growing grazers determines, to a large extent, the grazing impact of the zooplanktonic community on the phytoplankton assemblage that develops in the Arabian Sea during the southwest monsoon (upwelling). The grazing impact in turn modulates the flux of carbon to depth and is an important factor in the spatial and temporal patterns in carbon deposition in this region. In the Arabian Sea off Oman, carbon fluxes driven by large, seasonal changes in the grazing community of the upwelling area can be studied in combination with investigation of the grazing contribution to carbon fluxes associated with the perennially oligotrophi c region of the central Arabian Sea. A steep gradient in oxygen concentration located at approximately 150 meters acts to restrict most epipelagic grazers to a surface layer above this depth. The role of the epipelagic meso- and macrozooplanktonic grazers will be studied using: multiple opening/closing nets (MOCNESS) to determine distribution and abundance with particular attention to the oxic-suboxic interface and incubation experiments to determine ingestion, fecal pellet production, and growth rates