On Mechanisms of Physical and Biological Links Between Coastal and Open-sea Waters in Marginal Seas

In marginal and semi-enclosed seas the relation of shallow to deep-water areas is much higher, than in other parts of the ocean. As a result, there are higher concentrations of terrigenous nutrients and contaminants, and their positive as well as negative effects strongly depend on vertical and horizontal mixing in shallow and deep parts of the sea. Biological characteristics, especially chlorophyll and phytoplankton concentrations, change in conformity with local physical parameters and nutrients distribution. Experimental investigations in the shelf and near-shore areas of the Sea of Japan, supplemented by satellite observations data, have shown that small-scale processes in boundary bottom layers in shallow area, responsible for terrigenous material supply into water, are linked to larger-scale processes in deeper parts of the sea. The main mechanisms of that linkage are inertial, gravitational and inertia-gravitational internal waves generated over the continental slope, were the most effective interaction of tides and meso-scale eddies and exchange of energy between horizontal and vertical motions take place. In the seas with stable temperature stratification internal waves in a shoaling thermocline transform into series of discrete boluses with trapped cold cores, which penetrate into vertically homogenous zones and in that way lead to additional horizontal fluxes of mass and momentum. It is worth to note that eddies moving along shelf boundaries are at the same time generators of small-scale mixing processes in near-shore waters and consumers of the mixing results. So we suggest that information on eddies, obtained with the help of satellites, together with tidal calculations, can be used for forecasting of phytoplankton distribution and blooms in marginal seas.