This book is the outcome of a NATO Advanced Research Workshop on "The
Eastern Mediterranean as a laboratory basin for the assessment of
contrasting ecosystems" that was held in Kiev, Ukraine, March 23-27,
1998. The scientific rationale of the workshop can be summarized as
follows. The Eastern Mediterranean is the most nutrient impoverished and
oligotrophic large water body known. There is a well-defined eastward
trend in nutrient ratios over the entire Mediterranean that starts at
the Gibraltar Straits and, through the western basin, proceeds to the
Ionian and Levantine Seas. Supply of nutrients to the entire
Mediterranean is limited by inputs from the North Atlantic and various
river systems along the sea. The unique feature of the Mediterranean is
the presence of an eastward longitudinal trend in available
nitrate/phosphate ratios. This apparently induces a west-to-east
variation in the structure of the pelagic food web and trophic
interactions. In this context the Mediterranean, and in particular its
Eastern basin, provides probably a unique platform to explore the
hypotheses related to the suggested phosphate-limitation on production
and to the shift between "microbial" and "classical" modes of operation
of the photic food web. The major exception of the overall oligotrophic
nature of the Eastern Mediterranean is the highly eutrophic system of
the Northern Adriatic Sea. Here, during the last two decades the
discharges of the northern rivers (especially of the Po), together with
municipal sewage, have led to a very marked increase of nutrients and
subsequent imponent eutrophication events.