Italy - The Orbetello Lagoon and the Tuscan Coast
335
gases from the bottom, and sometimes fish kills (Lenzi and Salvatori
1986; Lenzi 1992). This has led to a considerable reduction of fish catch
from about 200 kg ha -1 to 120 kg ha -1.
Besides eutrophication stress, benthic communities also suffer periodically from detrimental effects of low water levels and the consequent
decomposition of the dying macroalgae followed by anoxia and development of toxic hydrogen sulphide. Owing to all these causes, the resilience
of lagoon communities has greatly decreased: communities are not able
to recover during the short-term marine influences.
14.2.5 Adopted Ways of Management
In order to limit further negative effects on the lagoon ecology in the
future, some management decisions have been made.
Three pump systems have been set up at the lagoon mouths of Nassa,
Ansedomia and Fibbia with pumping capacities of 4000 I s -1 in 1982
increased to 8000 I S-1 in 1993 at Nassa, 4000 I S-1 in 1986 at Ansedomia,
and 4000 I s - 1 in 1994 at Fibbia, respectively. In addition, since 1987
continuous harvesting and removal of 2500-10000 t wet weight of seaweeds per year have been carried out, employing boats.
Management decisions are aiming at increasing the water circulation
when tides are too feeble, and removal of part of the system's excess
energy which, in this case constitutes the seaweed biomass (Lenzi 1992).
In recent years, purification by plants as a way of treatment of both
domestic and agricultural waste waters has been suggested (Bombelli
et al. 1993). However, such solutions have met with difficulties from the
local administration which favours engineering solutions. Thus, a project
is under development constructing a big sewer trunk-line to collect all
wastes from the Orbetello lagoon basin and discharge them offshore.
14.2.6 Marine Coastal Areas Around the Orbetello Lagoon
The marine coastal areas around the Orbetello lagoon are important,
because of their high diversity of submerged biocoenoses due to the wide
range of substrates which include mud, sand, and rocky bottoms. Wide
meadows of Posidonia oceanica and Cymodocea nodosa can be found
near the Parco Naturae Maremma (oof the Uccellina Hills) and along the
coast of Monte Argentario (Lenzi and Micarelli 1993; Fig. 14.1). Two of
these meadows are Posidonia barrier reefs (Lenzi 1987).
The increase in human population during summer has brought about
several almost insoluble problems. At present, all wastewaters, treated or
335
gases from the bottom, and sometimes fish kills (Lenzi and Salvatori
1986; Lenzi 1992). This has led to a considerable reduction of fish catch
from about 200 kg ha -1 to 120 kg ha -1.
Besides eutrophication stress, benthic communities also suffer periodically from detrimental effects of low water levels and the consequent
decomposition of the dying macroalgae followed by anoxia and development of toxic hydrogen sulphide. Owing to all these causes, the resilience
of lagoon communities has greatly decreased: communities are not able
to recover during the short-term marine influences.
14.2.5 Adopted Ways of Management
In order to limit further negative effects on the lagoon ecology in the
future, some management decisions have been made.
Three pump systems have been set up at the lagoon mouths of Nassa,
Ansedomia and Fibbia with pumping capacities of 4000 I s -1 in 1982
increased to 8000 I S-1 in 1993 at Nassa, 4000 I S-1 in 1986 at Ansedomia,
and 4000 I s - 1 in 1994 at Fibbia, respectively. In addition, since 1987
continuous harvesting and removal of 2500-10000 t wet weight of seaweeds per year have been carried out, employing boats.
Management decisions are aiming at increasing the water circulation
when tides are too feeble, and removal of part of the system's excess
energy which, in this case constitutes the seaweed biomass (Lenzi 1992).
In recent years, purification by plants as a way of treatment of both
domestic and agricultural waste waters has been suggested (Bombelli
et al. 1993). However, such solutions have met with difficulties from the
local administration which favours engineering solutions. Thus, a project
is under development constructing a big sewer trunk-line to collect all
wastes from the Orbetello lagoon basin and discharge them offshore.
14.2.6 Marine Coastal Areas Around the Orbetello Lagoon
The marine coastal areas around the Orbetello lagoon are important,
because of their high diversity of submerged biocoenoses due to the wide
range of substrates which include mud, sand, and rocky bottoms. Wide
meadows of Posidonia oceanica and Cymodocea nodosa can be found
near the Parco Naturae Maremma (oof the Uccellina Hills) and along the
coast of Monte Argentario (Lenzi and Micarelli 1993; Fig. 14.1). Two of
these meadows are Posidonia barrier reefs (Lenzi 1987).
The increase in human population during summer has brought about
several almost insoluble problems. At present, all wastewaters, treated or