Fundamental macroecology and energy pathways in the mesopelagic zooplankton and micronekton communities

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Greatest challenge marine scientists presently facing is concomitant with the ability of predicting oceanic ecosystem and food web responses to climate change and pollution impacts. These are both possible when changes are detected but meaningless unless they translated into policies and management actions. The twilight or mesopelagic zone (200-1000 m depth) comprises 20% of the Earth oceans volume. It is vast, currently underexploited and remains largely understudied. However, it holds a great ecosystem service potential for the food provision (food security), nutraceuticals (e.g. essential oils), climate regulation (climate change mitigation) and biodiversity (Earth system resilience). Mesopelagic layer is important in both controlling marine productivity and sequestering anthropogenic carbon dioxide. Biological processes (plankton trophic dynamics, vertical migrations, decomposing rates.) are highly significant to air-sea interactions. A long-term goal of the proposed research is to develop a broad understanding of foundational ecological principles driving the composition, diversity, density and stability of the oceanic mesopelagic plankton and micronekton. First, 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. Short term goals of the proposed study in the mesopelagic zone will (a) contribute to a characterization of the composition and vertical structure of mesopelagic plankton and micronekton; (b) link structure, density and diversity of mesopelagic food webs to overlaying productivity, as well as to oxygen concentrations and acidity; (c) quantify the role of the mesopelagic zone in transferring energy to upper trophic levels, including fisheries production, as well as carbon sequestration, particularly carbon active transport from surface layers into midwaters by different groups of micronekton, and the "cryptic food web" responsible for the reverse carbon transport from mesopelagic to epipelagic layers; and (d) assess our abilities in predicting effects of mesopelagic processes on overall ocean productivity as well as future fisheries productivity. By providing novel information on midwater food webs, this proposal will lay foundation for the development of an interdisciplinary, multinational initiative to understand the mesopelagic ecosystem, its role in the marine carbon cycle, its ability to react to climate change and pollution challenges as well to develop ecosystem-based management in the open ocean.