Biological processes in the mesopelagic zone of the North Pacific: active carbon transport

海洋生态学家面临的一个重大挑战是能够预测气候变化对海洋、特别是深海中上层生态系统的影响，包括酸化、变暖和氧气减少。生物去除上层真光带中的碳，并将其输出到更深的水域，称为生物泵，在决定二氧化碳在表面的交换方面发挥着可变但重要的作用。从真光层被动和主动输出的90%以上的有机物在中深海层内再矿化，该层从真光带底部(~100米)延伸到超过1000米的深度。其中一些物质以十年或更少的营养物质、微量元素和二氧化碳的形式返回海面，而其余的有机物质转移到深海内陆并储存数千年。尽管重要而辽阔，但中大洋领域是海洋中研究最少的区域之一，因此我们预测推动真光带、深海和海洋边缘之间二氧化碳和营养物质交换的过程的能力有限。拟议研究的长期目标是广泛了解推动海洋中上层浮游生物和微型浮游生物的组成、多样性、密度和稳定性的基本生态原则。我们希望确定极地、温带和热带地区中上层海洋生态系统在结构和碳循环方面的不同/相似之处；第二，建立一个生态系统模型(未来的合作努力)，在上层海洋-中上层海洋-底层海洋之间提供机械联系。拟议研究的短期目标将侧重于东北太平洋中表层浮游生物和微型浮游生物的组成和垂直结构，其空间重点将是：(A)有助于描述东温带和北冰洋次太平洋中上层浮游生物和微型浮游生物的组成和垂直结构；(B)中层浮游生物和微型浮游生物的结构和多样性与覆盖生产力以及次表层氧浓度之间的联系；(C)用不同的微吨组量化从表层向中水转移的碳活性总量；(D)对“神秘的食物网”进行定量评估。这将建立在温哥华岛西海岸和PAPA站(太平洋次北极西部)的长期监测方案提供的研究机会的基础上。如果中水区域将成为未来捕捞的目标，拟议的研究对全球渔业将是重要的。广泛地说，它将用于开发北太平洋生物物理/渔业耦合模式的合作努力。通过提供关于水中食物网的新信息，这一提议将为制定跨学科的多国倡议奠定基础，以了解中上层生态系统及其在海洋碳循环中的作用，并在公海发展基于生态系统的管理。

A significant challenge for marine ecologists is to be able to predict climate change impacts, including acidification, warming and oxygen decline, on marine, particularly deep-sea, pelagic ecosystems. Biological removal of carbon from the upper, euphotic zone and export to the deeper waters, called the biological pump, plays a variable but significant role in determining carbon dioxide exchange at the surface. Greater than 90% of the organic matter exported both passively and actively from the euphotic zone is remineralized within the mesopelagic layer, which extends from the bottom of the euphotic zone (~ 100 m) to depths greater than 1000 m. Some of this material is returned to the surface as nutrients, microelements and carbon dioxide on decadal scales or less, while the remaining organic material is transferred to the deep ocean interior and stored for millennia. Despite importance and vastness, the mesopelagic realm is among the least studied regions of the ocean and thus our ability to predict the processes driving exchange in carbon dioxide and nutrients between the euphotic zone, deep-ocean and ocean margins is limited. The long-term goal of proposed research is to develop a broad understanding of the fundamental ecological principles driving the composition, diversity, density and stability of the mesopelagic plankton and micronekton in the ocean. We would like to identify the diss-/similarities in the structure and carbon cycling of mesopelagic zones in polar, temperate and tropical regions; second, to build an ecosystem model (future collaborative effort) that provides mechanistic links between epipelagic-mesopelagic-bathypelagic realms. The short term goals of the proposed study with the spatial focus on the NE Pacific mesopelagic zone will (a) contribute to a characterization of the composition and vertical structure of mesopelagic plankton and micronekton in the eastern temperate and sub-Arctic Pacific; (b) link structure and diversity of mesopelagic food webs to overlaying productivity, as well as to subsurface oxygen concentrations; (c) quantify the total carbon active transport from surface layers into midwaters by different groups of micronekton; and (d) assess quantitatively the “cryptic food web”. This will be built upon research opportunities provided by the long-standing monitoring programs off the west coast of Vancouver Island and at the Station Papa (western sub-Arctic Pacific). The proposed research will be important to global fisheries if midwater realm will become targeted for the future harvest. Broadly, it will be used in a collaborative effort to develop a coupled biophysical/fishery model of North Pacific. By providing novel information on midwater food webs, this proposal will lay foundation to the development of an interdisciplinary, multinational initiative to understand the mesopelagic ecosystem and its role in the marine carbon cycle as well to develop ecosystem-based management in the open ocean.