![]() ![]() Yoder and Ishimaru 11 reported unusual high concentrations of phytoplankton (especially of two diatoms, Skeletonema costatum and Asterionella japonica) in DW cascaded off the southeastern United States continental shelf, at depths higher than 100 meters. Although some studies have documented episodic changes of abundance, biomass and composition of plankton along water column as result of winter convective events 6, 7, 8, 9, 10, studies on the effects of shelf DW advection on the plankton communities are still insufficient. DSWC off the shelf break has been recognized as having a major role in bringing oxygen to deep water masses 3 and, by providing cross-shelf transport of organic matter, nutrients, oxygen and organisms, it has the potential to change the biodiversity of deep-sea communities, affecting biogeochemical cycles, and influencing the overall deep-sea functioning 3, 4, 5. Although more than 60 sites of cascading have been documented around the world, due to its highly intermittent nature both in time and in space, the wider-scale significance of this phenomenon has still to be quantified 1. Once formed those waters descend down the continental slope as near-bottom gravity current or as intermediate-depth intrusion 1. cooling or salification of coastal waters). The dense shelf water cascading (DSWC) is a type of gravity current, occurring when dense water (DW) forms over the continental shelf due to atmospheric forcing (i.e. The open-ocean dense water convection has long been acknowledged as substantial player in the global thermohaline circulation, while only recently the role of dense water formation over the shelf and cascading off the shelf break 1, 2 has been recognized. We conclude that the predicted climate-induced variability in DW formation events could have the potential to affect the ecosystem functioning of the deeper part of the Mediterranean basin, even at significant distance from generation sites. The Lagrangian numerical model set up on this diatom confirmed that DW flow could be an important mechanism for plankton/particles export to deep waters. DWs showed unusual high abundances of Skeletonema sp., a diatom that bloomed in the north Adriatic during DW formation. Results indicated a relatively higher contribution of heterotrophs in DW than in deep resident water masses, probably as result of DW-mediated advection of fresh organic matter available to consumers. 460 km south the area of origin and compared to resident ones in term of plankton biomass partitioning (pico to micro size) and phytoplankton species composition. Following the 2012 north Adriatic Sea cold outbreak, DW masses were intercepted at ca. ![]() However, whether DW flow across shelves may affect the composition and structure of plankton communities down to the seafloor and the particles transport over long distances has not been fully investigated. Dense waters (DW) formation in shelf areas and their cascading off the shelf break play a major role in ventilating deep waters, thus potentially affecting ecosystem functioning and biogeochemical cycles.
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