Figure 5. Composite echogram showing ring structures.
Physical - biological interactions are fundamental to the production and reproduction of marine life. These large-scale interactions can be observed through coincident distribution patterns of organisms and environmental variables (e.g. temperature).
Direct physical-biological coupling is more difficult to observe, although internal waves are frequently mimicked in plankton distribution patterns as recorded by acoustic systems.
During the MAR-ECO cruise the scientific echosounders on the vessel recorded at least four clearly defined ring structures of planktonic organisms over horizontal scales ranging tens of kilometres. Due to the change in current flow at the centre of the structure, we assume these structures to be rings or eddies created either by topography, collision between water masses, or, most probably, an interaction between these factors.
The structures were recorded east of the mid-Atlantic Ridge in the northern part of the study area and could potentially originate from water flow through the Charlie-Gibbs Fracture Zone. To our knowledge such large scale physical–biological coupling has not been previously observed.
Scientists to be credited: Olav Rune Godoe, John Horne, Stein Kaartvedt, Caristiona Anderson, Ruben Patel