Data Trawler - Project details

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Project details

Title: Ecological and carbon sequestration role of mesopelagic organisms in the Southern Ocean
Id: 2561
Investigator(s): Ben Scoulding
CSIRO Oceans & Atmosphere - Hobart [details]

Rudy Kloser
CSIRO Oceans & Atmosphere - Hobart [details]

Description: The small crustaceans, squids, fishes and gelatinous organisms that make up micronekton are a key biological component of the worlds’ oceans many making nightly migrations from mesopelagic 200-1000 m depths to the surface epipelagic 0-200m depths. Understanding their diversity, distribution, biomass and energetic needs are key to further understanding the carbon cycle and linking primary production to top predators. Commonly nets, optic and acoustic samplers are used to determine the taxonomy, size, biomass, trophic linkage and energetics of zooplankton and micronekton. Each of these sampling methods have bias and uncertainty that need to be quantified prior to attributing changes within and between regions. In particular for the gelatinous community that covers a wide range of taxonomic and energetic groups that are difficult to sample with nets. To improve vessel mounted acoustic and net sampling methods of macro-zooplankton and micronekton a new profiling multi-frequency acoustic optical system has been developed with the ultimate aim of it being used as a remote sampling tool. On this voyage we will be testing the next phase of a profiling lagrangian acoustic and optical probe (PLAOS) to sample these organisms to depths of 1000 m. These tests will involve detailed sampling of the repeatability of the measurements when varying lighting, using new broadband acoustic sensors and a new buoyancy engine to enable the system to do repeat profiles. A RMT8 single wire net will be used to capture micronekton for species identification and isotope studies. Development of this methodology and technology will significantly advance our knowledge of micronekton biomass and distribution and provide the necessary structure and function understanding for the development of carbon and ecosystem models of the open ocean linking to the ACE CRC carbon program as well as the MESOPP ecosystem program. It is envisaged that the majority of the sampling will be done at night for both the PLAOS and net sampling working around the other projects as needed. We envisage ~10-12 PLAOS deployments and ~5 net deployments during the voyage.
Years: 2020

List of surveys that this project was on.

Use [details] link to view survey details (map, reports, metadata etc) including links to download data.

Survey InvestigatorDescription

Elizabeth Shadwick (CSIRO O&A) The primary objective is to first deploy a new set of SOTS moorings (SOFS-12 and SAZ-25) and then recover the existing SOTS moorings (SOFS-11 and SAZ-24). Each of the SOTS moorings delivers to specific aspects of the atmosphere-ocean exchanges: • the SAZ sediment trap mooring collects samples to quantify the transfer of carbon and other nutrients to the ocean interior by sinking particles and investigate their ecological controls. • the Southern Ocean Flux Station (SOFS) mooring measures meteorological and ocean properties important to air-sea exchanges, ocean stratification, waves, currents and biological productivity and ecosystem structure. Water samples are collected for more detailed nutrient and plankton investigations after recovery. Ancillary work will obtain supporting information on atmospheric and oceanographic conditions using CTD casts, underway measurements, Continuous Plankton Recorder and autonomous glider, and potentially casts of a bio-optical sensor package. Voyage objectives: 1. Deploy SOFS-12 meteorology/biogeochemistry mooring. 2. Deploy SAZ-25 sediment trap mooring. 3. Recover SOFS-11 meteorology/biogeochemistry mooring. 4. Recover SAZ-24 sediment trap mooring. 5. CTD sampling (2 cast to 4550m, 2 to 600m) at the SOTS site, including collecting samples for nutrients, oxygen, dissolved inorganic carbon, alkalinity, and particulate matter analyses. 6. Ship meteorological observations at SOFS buoy for comparisons. 7. Deployment of CSIRO glider for satellite calibration validation during the SWOT fast sampling phase, in support of IN2023_V07. 8. Potential recovery of BGC-Argo float, or CSIRO glider, using new recovery device. 9. Tow CPR on transit to SOTS (after the seamount survey). 10. Carry out underway air and water sampling and sensor measurements, including bio-optics and bio-acoustics.
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