Seasonal patterns of phytoplankton productivity and abundance in nearshore oligotrophic waters of the Levant Basin (Mediterranean)

A biweekly sampling program from two stations at the easternLevant Basin was carried out during a 1-year period (1983).The first station (neritic) was located 2 km offshore over theIsraeli continental shelf, while the second (pelagic) was located10 km offshore slightly beyond the continental shelf. It wasfound that during summer the relatively close pelagic watershad chlorophyll a concentrations comparable with the most oligotrophicdeep sea regions of the world's oceans. During winter and spring,profound fluctuations were observed in both phytoplankton standingcrop and primary productivity at the neritic station. This wasin response to weather phenomena, such as heavy rains or storms,which did not affect the pelagic Station to such an extent.The picoplanklon size fraction (<3 µm) dominated atthe neritic station during summer and fall, while the nanoplanktonfraction (3–20 µm) dominated during spring. At thepelagic station the picoplankton fraction dominated almost allyear round, but it is suspected that some portion of it wasphotosynthetically inactive.