Plankton Distribution in the Mediterranean Sea, 1962-1963

Naval Oceanographic Office ships collected 34 plankton samples in the Mediterranean between 6 July 1962 and 24 August 1963. Species composition was quite similar throughout the sea. Ninety-four genera of plankters were identified from the western sector and 84 genera from the eastern sector. Seven of 11 major taxa were two to ten times more numerous in the western portion of the sea and only two of these taxa proved more numerous in the eastern portion. About 20 percent of the forms listed were bioluminescent. Many plankters enter the Mediterranean from the Atlantic through the Strait of Gibraltar and are swept eastward by the prevailing currents, becoming progressively scarcer towards the eastern sector of the sea.