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PHYTOPLANKTON STRUCTURE AND DYNAMICS IN THE CONTINGENCE ZONE
BETWEEN THE WATERS OF THE DANUBE-BLACK SEA CANAL AND THE SEA WATERS


N. Bodeanu and Georgeta Ruta

Romanian Marine Research Institute Constanta

Abstract
This paper deals with the qualitative and quantitative structure and
dynamics of the phytoplankton in the contingence zone between the
Danube - Black Sea Canal waters and sea waters, paying attention to 
the relations between the two types of algal populations getting into
contact in that zone: the marine and brackishwater populations 
(peculiar to the Canal). The list of the planktonic algal species 
found during the research period (October 1992 - August 1993) is 
herein included; information is given for each characteristic of the
zone regarding the algal flora structure by systematic and ecological
groups, on the contributions of main algal groups to the phyto-
plankton quantity and on its yearly means; the annual dynamics of the
planktonic algal flora is described including their peaks distinct
from their amplitude point of view and calendaristic moment of
occurrence and predominant species for each sector. After analysing
the relations between the algal flora originated in the Canal and 
that in the sea, it has been noted the majoritary algal fraction
of each sector includes the autochtonous species of the basin (river
or marine basin) beloging to that sector, and the contribution of the
freshwater taxonomic elements in the sea area next to the Canal is
almost equal with that of the marine and brackiswater elements from
the sea which entered the neighbouring sector of the Canal. The
quantitative contributions of the marine and brackishwater 
populations to the phytoplankton of the mixed waters of the river-
marine harbour and of the Canal as well as the quantitative 
contributions of the freshwater populations to the phytoplankton
of the river-marine harbour and adjancent marine sector are 
presented. This paper ends with some considerations on the way in
which the prognosis regarding the phytoplankton ecological
implications induced by the inaguration of the Canal has been
confirmed. Some theoretical and practical conclusions in 
connection with the problems discussed in this paper are also
included.
Key words: phytoplankton, the Black Sea, the Danube-Black Sea Canal