| The investigation design implied studying integral nutritive base of fish not by artificial depth series but by zones naturally formed by temperature and salinity gradients in the water column of the Black Sea. The synchronous biological, hydrochemical and hydrological observations were conducted mainly in the western part of the sea during summer 1951, spring 1952, autumn 1954 and winter 1956. Assessment of the food supply in pelagic zone suggested discrimination between fodder and inedible plankton. To reliably figure out nutritive base for warm-water and for cold-water fishes, the depth of each naturally generated seawater zone, food capacity of which depends on season, should be taken into consideration. Hypothetically, warm- and cold-water fishes... |
