The problems of the Emilia Romagna coastal waters: facts and interpretations

Abstract

In this work, the two main problems concerning the upper Adriatic coastal waters are examined: the so-called algal blooms and the gels or excretions. The former comprises the uncontrolled reproduction of microalgae causing an enormous mass of living matter which is incompatible with bathing, the decomposition of which causes oxygen consumption and the death of the animals living on the sea bottom. This phenomenon is not new along the Emilia Romagna coast but has become more severe during the last 15 years and is strongly connected with the polluting loads from the Po and other minor rivers along the coast. The latter — in respect to the upper Adriatic coastal waters during the summers of 1988 and 1989 — is due to the excretion of products which are normally emitted by algal cells with various functions and which, under circumstances still not completely understood, can reach enormous amounts as occurred in the summer of 1989. In the July of that year, it was calculated that about 10 000 km2 of sea were covered by a layer of gel. The nature of the compounds of which the gel is formed has been individuated in polysaccharides forming a structure incorporating 98-99% of water and which is completely harmless for humans. The most probable cause of the formation of these gels has been identified with the strong meteorological and climatic anomalies which characterized that period, traces of which have not been found in the data of the preceding 100 years.