ABSTRACT: The fatty acid compositions of amorphous aggregates were determined in samples collected in northern Adriatic regions of different eutrophication degree and in different seasonal conditions of the plankton communities. It was shown that healthy and active phytoplankton can be present in the aggregate communities, particularly various diatom species. Four different groups of aggregates were sorted by cluster analysis, comparing fatty acid proportions and ratios (C16:1/C16:0, C16:1/C18:1 and C16POLY/C18POLY). The growth stages of the aggregate diatom populations included the lag, exponential and stationary growth phases as well as decay phases. The aggregate diatom composition of several samples was significantly different from the surrounding water. The results confirmed a previous hypothesis that the northern Adriatic aggregates represent self sustaining communities developing throughout the summer.

KEY WORDS: Aggregates · Fatty acids · Phytoplankton · Diatoms · Northern Adriatic

Published in MEPS Vol. 139 (1996) on August 29
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1996