Spatial and Temporal Distribution of Phytoplankton a Mediterranean Estuarine Canal System

Abstract

Phytoplankton composition and distribution in a Mediterranean coastal drainage canal is discussed. The study includes the end portion of the Albufera of Majorca Gran Canal and it was studied from December 1992 to November 1994. Physical and chemical gradients are affected by fresh and marine water fluxes, which are responsible for phytoplankton heterogeneity. There is a gradual reduction in phytoplankton abundance (chlorophyll a and cells) from the inland sites to the outer I marine) ones. The phytoplankton is dominated by small-sized forms, mostly under 5 µm. Along with the high cell abundance, this indicates the eutrophic character of this system. The studied system shows the two phytoplankton dynamic models described for temperate estuaries. The innermost part of the canal shows two bloom periods throughout the annual cycle, one in the spring and' the other in the autumn, both associated with water input from the Albufera. Nearest the sea, the phytoplankton dynamics, characterised by summer bloom, is tied up with mineralization processes of the organic matter and mainly with phosphorus recycling from the sediment. The filter role of these coastal wetlands is also confirmed.