Damaged for decades by anchors scraping the seabed, new eco-mooring are designed to be less harmful to the posidonia plants.

Diver Makis Sotiropoulos used a special drill to bore three metres into the seabed before installing the ecological anchorage with its two symmetrical fins.

"We pull upwards to lock it in place before attaching a chain and a marker buoy," he told AFP.

The buoy then enables a vessel to moor "in complete safety", he said.

The project is run by the Greek ministry of merchant marine, which aims to extend it across the country's 13,000 kilometres (8,000 miles) of coast, 70 percent of which is covered by Posidonia seagrass meadows.

"When we establish a nationwide network of mooring buoys, then those with boats will be able to tie up safely, quickly and efficiently and at the same time the seabed will not be damaged," ministry secretary general Evangelos Kyriazopoulos told AFP.

The ribbon-like plants have been classified as a "priority habitat" by the European Union for various marine species.

"Posidonia is among our best allies in the fight against climate change and deserves our full attention," said Maria Salomidi, a researcher at the Hellenic Centre for Marine Research (HCMR).

The seagrass meadows "capture and store carbon beneath their rhizomes (root stems), produce oxygen, filter and purify the water, and support biodiversity," she said.

- Severe damage -

A large number of Posidonia root stems are torn out when anchors are raised.

"Very often I have observed anchors lying on posidonia meadows," said Rouli Prinianaki, a diver and member of the NGO Aegean Rebreath, which is part of the campaign.

The Greek state organisation for environment and climate change (OFYPEKA) has termed anchoring "one of the most significant threats" to the plants.

Around 40 ecological moorings have been installed in Greece in recent years, mostly in marine parks of the Ionian Sea and near the island of Alonissos.

Fifteen eco moorings have been installed in Alonissos "but they are not enough for the thousands of boats in summer," said Spyridon Iosifidis, a fish specialist at the OFYPEKA directorate for the Sporades island group.

- Need for legislation -

Experts say Greece must speed up and broaden the installation of ecological moorings for pleasure boats that flock to its bays in summer.

Athens "needs to legislate to protect seagrass meadows and allow them to regenerate" following the example of the Balearic Islands in Spain and the French Mediterranean coast, said WWF Greece biologist Vangelis Paravas.

According to HCMR, the problem is particularly acute along the coasts and islands of the Ionian Sea, the Saronic Gulf and the Cyclades, where over-tourism is threatening certain areas.

"The number of vessels has increased and there is neither monitoring nor information," said HCMR's Salomidi.

Managing the moorings can be a profitable commercial activity, promoting high-quality tourism, she adds.

"It is extremely important to develop such a network of mooring buoys across the country, both to protect the environment and to support the growth of maritime tourism," the ministry's Kyriazopoulos said.