2 - Ship-based sampling approaches

This module introduces the main ship-based sampling approaches that are implemented to measure and understand ocean biogeochemistry and ecology.
The first module will be dedicated to the carbonate system and introduces the fundamental concepts of inorganic carbon chemistry in marine environments, along with the biogeochemical and physical factors that regulate air–sea CO₂ fluxes. It highlights the role of the ICOS (Integrated Carbon Observation System) research infrastructure and the importance of high-quality sea surface pCO₂ measurements in constraining the ocean carbon budget. The course also covers the principles of operation of instruments used for autonomous measurements of carbonate system parameters on board Ships of Opportunity, with a focus on the systems installed on the research vessel Gaia Blu, which measure pH, using a spectrophotometric system, pCO₂ and total alkalinity.
The second module focuses on plankton net sampling. The WP2 closing net represents a targeted, ship-based sampling method designed to collect meso-zooplankton and other marine particles at specific depths. Unlike open nets, the closing mechanism allows for discrete sampling at predefined vertical intervals, minimizing contamination between water layers. This approach is essential for studying the vertical distribution, diel migration, and biodiversity of zooplankton communities. Deployed from research vessels during oceanographic cruises, the closing net enables high-resolution, depth-stratified biological data collection, supporting ecosystem assessments and long-term monitoring strategies. This module is going to present also the Underwater Vision Profiler 6 (UVP6) that is an advanced optical instrument deployed from research vessels to capture high-resolution images of particles and plankton in the water column. Integrated into CTD rosettes or deployed autonomously, the UVP6 collects quantitative data on particle size spectra, marine snow, and mesozooplankton without the need for net sampling. It enables real-time profiling of vertical distributions from the surface to deep waters, supporting ecological studies and biogeochemical assessments. Within ship-based sampling strategies, the UVP6 provides a non-invasive, complementary tool to traditional nets, enhancing the spatial and temporal resolution of marine biodiversity observations.
The third module is dedicated to the water sampling from the rosette, measurements of the underwater light field and its optical constituents. The rosette/CTD system will be presented and strategies to follow to optimize the water sampling of marine planktonic ecosystems will be described. Ship-based profiling techniques and instruments to measure undewater optics are also described. Focus is given on radiometers, absorption and scattering meters, and Secchi disk.