JGOFS (Arabian Sea): Effects of the Oxygen Minimum Zone on Mesozooplankton Distributions and Food Webs

小行星9310590 这项研究是阿拉伯海全球海洋通量联合研究的一部分，研究的问题是，阿拉伯海真光层以下广泛存在的亚氧条件是否将后生动物的碳循环主要限制在最低含氧层以上和以下的区域，以及这是否导致深层碳浓度（以浮游生物量的形式）升高。 该项目有两个重点：（1）测量中层浮游动物的分布和按大小划分的深海垂直层生物量，特别注意最低含氧区及其上下界面;（2）检查最低含氧区对浮游动物营养关系的影响，包括浮游动物与细菌之间的潜在联系。 垂直分层的浮游动物样品下降到3500米，将采取在四个季节与MOCNESS浮游生物网系统白天和黑夜在四个密集的JGOFS站和间隔沿着断面的站点之间的中型浮游动物的分布和大小分级的生物量的测定。 浮游动物的肠道内容物将通过透射电子显微镜进行分析，以确定营养网。 最低含氧层的上下界面可能是浮游动物和颗粒丰度高以及有机物质密集加工的地点，将特别作为研究分布和食物网的目标。 最低含氧量区内的中型浮游动物丰度低，可能有助于增加有机物质向海底的通量，因为这些食草动物对中层水颗粒物质的利用将减少。 在最低含氧区界面，中型浮游动物丰度高，食物链短（从细菌到浮游动物），这表明在狭窄的深度窗口内对有机物质进行了激烈的处理，可能起到了过滤沉降颗粒的作用。 这项工作将有助于阐明有机物质在通过水柱到达海底的过程中如何发生变化。 它将有助于了解阿拉伯海的季节性季风循环和由此产生的生产力高峰是如何与碳通量和沉积相联系的，并可能为预测气候变化的影响提供类比。

9310590 Gowing This research, part of the Joint Gobal Ocean Flux Study (JGOFS) of the Arabian Sea, addresses the question of whether the widespread suboxic conditions below the euphotic zone in the Arabian Sea restrict carbon cycling by metazoans primarily to regions above and below the oxygen minimum zone and whether this results in elevated carbon concentrations (in the form of plankton biomass) at depth. This project has two foci: (1) the measurement of mesozooplankton distributions and size-fractionated biomass in vertical strata to the deep sea, with particular attention to the oxygen minimum zone and its upper and lower interfaces, and (2) examination of oxygen minimum zone effects on zooplankton trophic relationships, including the potential zooplankton-bacteria link. Vertically stratified zooplankton samples down to 3500 m will be taken during four seasons with a MOCNESS plankton net system day and night at the four intensive JGOFS stations and at intervals along transects between the stations for the determination of mesozooplankton distributions and size-fractionated biomass. Gut contents of zooplankton will be analyzed by transmission electron microscopy for determination of trophic webs. The upper and lower interfaces of the oxygen minimum zone, which may be locations of high zooplankton and particle abundances and intense processing of organic material, will be specially targetted for studies of distributions and food webs. Low mesozooplankton abundances within the oxygen minimum zone may contribute to enhanced fluxes of organic materials to the sea floor, because the utilizatimn of particulate material in midwater by these detritivores would be reduced. High mesozooplankton abundances and a short food chain (bacteria to zooplankton) at the oxygen minimum zone interfaces would suggest intense processing of organic material localized within a narrow depth window, possibly acting as a filter for sinking particles. This work will help elucidate how organic material may be altered during passage through the water column to the sea floor. It will contribute to understanding how the seasonal monsoon cycle of the Arabian Sea and resultant productivity peaks are coupled to carbon fluxes and deposition and may provide analogies for predicting effects of climate change.