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Mesozooplankton component. General objective : Quantitative assessment of its biomass and production and its impacts on phytoplankton stocks and vertical matter flux. Approaches :
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Mesozooplankton component • General objective: Quantitative assessment of its biomass and production and its impacts on phytoplankton stocks and vertical matter flux. • Approaches: • 1. The biomass (as organic carbon and nitrogen) determined by combination on size structure (estimates based on OPC/ZOOSCAN measurements)* and direct determination of carbon and nitrogen contents(with CHN)* in mesozooplankton fractions. • 2. The samples for description of zooplankton communities*. • 3. Complementary process studies to estimate biological rates (details to be discussed during this meeting **) and fluxes through the compartment. • - Egg production experiments* • - Others • *: Innovative approach • *: Classical approach
Details ►Sampling 1. - Bongo net tows for samples Standard: Depth from 200 m to the surface Alternatives: - Depth defined in real time observation from size particles distribution UVP (to be discussed). - Open-close nets 2. - Net tows for living organisms
►Processing on board: • 1. Collected samples • Conditioning samples for preservation • Conditioning samples for weighting C/N: filtrations • 2. Collected living organisms • 24 h Egg production experiments
►Measurement Lab OPC/ZOOSCAN: Fine resolution if the size-structured biomass Binocular: Faunistic distributions Counting from egg experiments
►Objectives : 1. Quantify mesozooplankton biomass (200 µm-2000 µm) based on a fine resolution of its size structure using OPC and ZOOSCAN, and CHN weighting. Deliverables - Total biomass - Size-fraction biomasses (200-300 µm;300-500 µm;500-1000 µm; >1000 µm) from OPC/ZOOSCAN and from CHN on similar size fraction - Fine size-distribution of biomass from OPC and binocular: define main contributors
►Objectives (suite): 2. Description of zooplankton communities Deliverables - Taxonomic tables per station - Identification of main contributors on size spectra 3. Derived index of zooplankton production with the slope of the biomass size spectrum Deliverables - Index of production - Derived fluxes as allometric relationship to weight: Respiration of planktonic communities by the use of biomass spectra and allometric relations
►Objectives (suite): 4. Estimate zooplankton production from classical method: egg production of copepods Deliverable: Egg production per female Egg production per biomass fraction – Secondary production