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The disappearance of a type of sea grass from the Medi terranean may
be as serious as the loss of the Amazon rainforest, say environmentalists.
If steps are not taken to stop the underwater ‘deforestation’, much of the
life in the Mediterranean will disappear. A survey by the environmental
group Greenpeace shows that heavy metals, insecticides, oil spills, fishing
and tourism all contribute to the decline of the sea grass.

Posidonia oceanica provides food and shelter for some 400 species of
algae and several thousand species of fish and molluscs. The extensive ‘forests’
of sea grass generate so much oxygen that they have been dubbed ‘the lungs
of the seabed’. A square metre of sea grass generates about 10 litres of
oxygen a day.

P. oceanica is a native of the Mediterranean, growing as far down as
40 metres where the water is clear enough for light to reach it. Javier
Romero, an ecologist at the University of Barcelona who has studied the
plant for 10 years, says losses have been especially obvious off the Costa
Brava, in the northeast, and off Valencia and Alicante farther south. ‘Where
tourism flourishes there is a general decline of P. oceanica.’

According to Marion Stoler of Green peace, untreated sewage encourages
the growth of plankton, which prevents light from reaching the grasses on
the sea floor. ‘Trawlers also wreck plantations by scraping the seabed.
Anchors from pleasure craft pull up the grass, and sandy beaches – created
to enhance the tourist value of certain coastal areas – wreak havoc among
the grass plantations,’ she says.

The sea grass is vital to the fishing industry; research has shown that
400 square metres of sea grass can support 2000 tonnes of fish a year. ‘Octopus
and sea bass, two favourite Spanish dishes, thrive on the sea grass plantations,’
says Romero. ‘It is absolutely fundamental to the proper functioning of
the Mediterranean ecosystem.’ The beds also help to protect the shore from
erosion.

France was first to raise the alarm about the shrinking beds of sea
grasses. ‘Paris adopted legislation for the protection of the grass when
the government realised that 50 per cent of the sea grass coverage had disappeared,’
Romero says. Spain is now drawing up similar plans to protect its sea grasses.