MAP Technical Reports Series No. 106 UNEP

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Figure 9 summarizes the most important sites of reported phenomena of eutrophication
in coastal and lagoon areas. Virtually all the countries around the Mediterranean offer more or
less obvious cases; although the northern shores are generally the most affected, the problem
of eutrophication is also causing serious problems in the south, and there is ground for fear that
these problems may assume much vaster proportions than at present. If forecasts are correct,
the population of the North African states will rise from today's 109,300,000 inhabitants to
208,000,000 in the year 2,025 (Agnelli Foundation, 1991). Considering further the development
stage of production technologies in these countries and the virtually total absence of
environmental policies, eutrophication problems will scale up in the future.
As to the scientific information available about Mediterranean eutrophication, coverage
provides a fairly satisfactory picture of the present situation, although the density of information
acquired on specific problems varies depending in part on the existence of qualified research
institutes and the availability of funds. Thus, the absence of data on the coastal waters of
Albania, Syria, Libya and Morocco makes it impossible to define the trophic status of their
transition waters.
5.2 Review of recorded incidents of eutrophication by regions and countries
5.2.1 Spain: Western Mediterranean
Alboran Sea. Diatom blooms occur periodically along the southern shores of Spain
from the Straits of Gibraltar to Almeria as a result of upwelling generated along the path of the
Atlantic current entering through the Straits of Gibraltar. Moving along the Andalusian coast and
offshore into the southern Alboran Sea at its eastern boundary, this current determines the socalled
Almeria-Oran Front which showed a permanent bloom recently described by Tintore et
al. (1989) and Martinez et al. (1990). The same conclusions were reached by Minas et al. (1983),
who emphasize that the high productivity of the basin to the North-West of the Alboran Sea is
strongly related to upwelling associated with the anticyclonic vortex generated by the flows of
Atlantic waters entering through the Straits of Gibraltar.
Localized eutrophication is reported in the Bay of Malaga, where Jmenez et al. (1986)
describe the presence of winter blooms. Cortes et al. (1985) also reported high values of
chlorophyll-a in the area off the city of Malaga in 1992; the authors indicate the effluents from
Malaga and the input of the Guadalhorce river as the main causal factors. Significant quantities
of dinoflagellates which produce PSP group toxins were also reported by Bravo et al. (1990)
along the Andalusia coastal area between Malaga and the Bay of Algeciras; in this case the
species was Gymnodinium catenatum which, in January-February 1989, was present with
concentrations in excess of 3,000 cells/l.
East coast and Baleares. Describing the distribution of nutrients in the Gulf of Sant Jordi
(Terragona), which is under the influence of the nutrient inputs of the Ebro river, Deya (1981)
emphasizes the fact that the development of the autotrophic biomass is phosphorus controlled.
At Barcelona, Margalef (1968) reports a case of "red tide" produced by Chattonella subsalsa. At
the port of San Carlos de la Rapita, geographically to the South of the Ebro delta, in May 1989
Delgado et al. (1990) observed a large bloom (28,000,000 cells/l) of Alexandrium minutum (a
dinoflagellate listed amongst the species capable of synthesizing group PSP toxins). Other
reports come from the Cullera zone, where diatoms (Thalassiosira and Chaetoceros species)
have generated blooms with values of 7,200,000 cells/l during the