Phytoplankton blooms in the oligotrophic open South Adriatic waters

Abstract

The phytoplankton bloom recorded in April 1987 in the offshore south Adriatic waters was compared with a less extensive bloom in April 1986. Differences between 1986 and 1987 hydrographic data occurred because of different hydrometeorological conditions. April 1987 was a period of a pronounced advection of eastern Mediterranean water ( S > 38.65%, T>14° C) into the Adriatic, and the extensive phytoplankton bloom was probably induced by earlier upwelling. The difference between the situations in 1986 and in 1987 can be attributed to the measurements being made at two different stages of the phytoplankton blooms. In 1986, the measurements were made during the first phase, whereas in April 1987 they were made during the late phase of the bloom. The complex dynamics of the south Adriatic waters probably involve upwelling/downwelling and advection.