The Management of Eutrophicated Waters
59
On the Atlantic coast, serious eutrophication problems have been
reported in Brittany with dire consequences for local tourism. Ulva proliferation is at the origin of the expression "green tides"; areas such as
Lannion Bay and the bay of St. Brieuc are particularly well documented
cases (Kopp 1977). The phenomenon has been recorded for over 20 years
since 1968, and is expanding in Lannion Bay to such an extent that there
alone, 10 years ago, some 25000 m 3 of Ulva lactuta and U. rigida were
gathered in a single season. These algae can reproduce throughout the
year and the freeing of reproductive cells is apparently linked with the
tidal cycle (Brault 1983). Ulva lactuta is, incidentally, spread over all
oceans. It is thus not surprising that it has caused a series of problems in
Denmark, where it proliferated in Odense Fjord.
In France still, algal proliferation has increased along the coasts of the
Languedoc-Roussillon and Corsica. The affected areas have extended to
St. Malo and the southwest (La Rochelle, salt water lakes of the Landes)
on the Atlantic and to Sete on the Mediterranean. In addition, the
phenomenon has expanded in time as it now occurs in May through
November.
No phytoplankton blooms have been reported for the Greek eastern
Mediterranean, viz. the Aegean, Ionian and Levantine seas, though high
nutrient content has been observed in several gulfs (Kavala, Patraikos,
Pagassitikos). Algal blooms are frequent in Saronikos Gulf where eutrophication is common. Intensive agriculture contributes to the situation (Panagotidis and Pagou 1990). Heavy concentrations of nutrients,
attributed to run-off and river discharge have been studied in the Gulf of
Alexandroupolis (Friligos and Karydis 1988). Red tides are not infrequent in this lagoon (1951, 1989).
Urbanization, industrialization, agriculture, harbor and canal
construction, tourism, drilling and marine mining have modified the
Black Sea's phytoplankton over the last decade and a half (Table 2.1). A
considerable biomass increase has been observed and blooms have
become more frequent (Bodeanu 1984, 1992). Reduction of nutrient
influx is an absolute necessity to curb the blooms, the massive algal
development and the eutrophication (Bodeanu 1992).
An ecological decline is threatening the Romanian coast. During 1989,
blooms attained their highest development ever (Bodeanu and Roban
1989; Skolka and Bolaga 1990). The strength of blooms and the intensity
of eutrophication had already been reported in 1984 (Bologa 1985/1986).
Benthic seaweeds showed a gradual, but continuous qualitative and
quantitative decline since mid-century (Bologa 1989). A very high
chlorophyll a content in the pre-Danubian Black Sea sector, observed for
some 20 years, is due to eutrophication (Bologa et al. 1985). Second only
59
On the Atlantic coast, serious eutrophication problems have been
reported in Brittany with dire consequences for local tourism. Ulva proliferation is at the origin of the expression "green tides"; areas such as
Lannion Bay and the bay of St. Brieuc are particularly well documented
cases (Kopp 1977). The phenomenon has been recorded for over 20 years
since 1968, and is expanding in Lannion Bay to such an extent that there
alone, 10 years ago, some 25000 m 3 of Ulva lactuta and U. rigida were
gathered in a single season. These algae can reproduce throughout the
year and the freeing of reproductive cells is apparently linked with the
tidal cycle (Brault 1983). Ulva lactuta is, incidentally, spread over all
oceans. It is thus not surprising that it has caused a series of problems in
Denmark, where it proliferated in Odense Fjord.
In France still, algal proliferation has increased along the coasts of the
Languedoc-Roussillon and Corsica. The affected areas have extended to
St. Malo and the southwest (La Rochelle, salt water lakes of the Landes)
on the Atlantic and to Sete on the Mediterranean. In addition, the
phenomenon has expanded in time as it now occurs in May through
November.
No phytoplankton blooms have been reported for the Greek eastern
Mediterranean, viz. the Aegean, Ionian and Levantine seas, though high
nutrient content has been observed in several gulfs (Kavala, Patraikos,
Pagassitikos). Algal blooms are frequent in Saronikos Gulf where eutrophication is common. Intensive agriculture contributes to the situation (Panagotidis and Pagou 1990). Heavy concentrations of nutrients,
attributed to run-off and river discharge have been studied in the Gulf of
Alexandroupolis (Friligos and Karydis 1988). Red tides are not infrequent in this lagoon (1951, 1989).
Urbanization, industrialization, agriculture, harbor and canal
construction, tourism, drilling and marine mining have modified the
Black Sea's phytoplankton over the last decade and a half (Table 2.1). A
considerable biomass increase has been observed and blooms have
become more frequent (Bodeanu 1984, 1992). Reduction of nutrient
influx is an absolute necessity to curb the blooms, the massive algal
development and the eutrophication (Bodeanu 1992).
An ecological decline is threatening the Romanian coast. During 1989,
blooms attained their highest development ever (Bodeanu and Roban
1989; Skolka and Bolaga 1990). The strength of blooms and the intensity
of eutrophication had already been reported in 1984 (Bologa 1985/1986).
Benthic seaweeds showed a gradual, but continuous qualitative and
quantitative decline since mid-century (Bologa 1989). A very high
chlorophyll a content in the pre-Danubian Black Sea sector, observed for
some 20 years, is due to eutrophication (Bologa et al. 1985). Second only