Zooplankton plays a crucial role in aquatic ecosystems, serving as indicators of water quality and linking lower trophic levels, such as algae, to higher levels, like fish. Its role in biogeochemical cycling is significant yet not fully understood. Accurate abundance estimates of zooplankton are essential for various research fields. Traditionally, plankton nets of various sizes and designs have been used to collect samples, each yielding different abundance estimates due to their unique sampling characteristics. To document these characteristics, the hydrodynamics of nine commonly used plankton nets were numerically investigated using computational fluid dynamics (CFD), specifically the Reynolds averaged Navier-Stokes (RANS) methods. The study focused on several nets, including the 1 m² MOCNESS, CalCOFI 1-m Ring net, Multinet Midi, and Bongo nets of different diameters, as well as three Apstein nets for microzooplankton sampling. Simulations of vertical tows assessed filtration efficiency, filtration pressure, and pressure distribution across the nets. Towing velocities for smaller mesozooplankton nets ranged from 0.5 to 2.3 knots, while microzooplankton nets operated between 0.07 and 0.66 m/s. The results were compiled into technical characteristic sheets for each net, providing valuable insights for researchers.
