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PROBLEMS CONCERNANT L'EUTROPHISATION MARINE 


M-T Gomoiu
Institut Roumain de Recherches Marines Constanta


Abstract
Based on the bibliography and the analysis of the present
state of the Black Sea coastal ecosystems, the authors
raises for the specialists discussion the problems concerning
the concept of marine eutrophication. In the paper a few 
definitions are quoted, including a possible one given by the
author: eutrophication (E) represents a complex process of
improving the trophic conditions for all the ecosystem levels,
a process which begins with the enrichement of basin waters
with nutrients up to the maximum level of the regulating
capacity of biogeochemical cycles without any disorder in the
reference ecosystem and first of all without diminishing the
oxygen concentration to critical levels; when the input of 
nutrients exceeds this maximum level, the eutrophication 
process turns into pollution. The author considers that the 
processes in the coastal marine ecosystems, which seem to be
similar to those occuring in lakes, could be defined for the
time being as a marine eutrophication syndrom (SEM) or an over-
fertilization syndrom (SSF). The meaning of the term "marine
eutrophication" as it results from the literature concerning
the Black Sea generally and the Romanian coast especially is
summarized in the paper as follows: 1. an increase in the 
quantities of nutrients;2. an increase in the global quantities
of phytoplankton and the apperance of red-tide cronically and
at higher and higher levels every year; 3. an increase in the
quantities of disssolved and particulate organic matter both in
sea water and sediments; 4. the appearence of hypoxic and anoxic
conditions; 5. a decrease in the number of zooplanktonic species
parallel with an increase in the density of dominant forms;
6. the disappearence or decrease in the populations of Zostera
or brown algae (Cystosera) and red algae (Phylophora) and the 
development of some species of green algae (Enteromorpha,
Cladophora); 7. mass mortalitiesof some benthic organisms and
modifications in the qualitative and quantitative structure of
bottom associations; 8. modifications in the structure of both 
fish populations and mammals (severe reduction of sturgeons 
stocks, the increase in the quantities of planktonofagous species;
the decrease in the dolphin stock, a.s.o.). In the end, the author
shows the necessity of further complex studies for understanding
and defining the marine eutrophication process and for taking
measures to limit overfertilization or marine pollution.