Underwater reforesting initiative in Gyaros

Underwater reforesting initiative in Gyaros

“For years, we’ve been witnessing the decline, but it has reached alarming levels over the past decade. Climate change and the proliferation of invasive species are exacerbating the situation. I fear what all this means for the Greek seas, especially for a country that invests a quarter of its GDP in marine-related services and activities,” says Maria Salomidi, a researcher at the Institute of Oceanography at the Hellenic Center for Marine Research (HCMR).

An experienced diver, Salomidi has participated in numerous research programs, witnessing firsthand the changes occurring beneath the waves. She – along with many other scientists – contends that the situation in Greece’s waters is far worse than commonly believed. Recent studies confirm what coastal residents and divers have empirically observed: the gradual degradation of crucial marine ecosystems.

To address this issue, scientists across the Mediterranean are seeking solutions, including better management practices such as fishing regulations and restoration efforts. One such initiative, originating in Italy, focuses on replanting shallow reefs. This approach, tailored to the Eastern Mediterranean, is now being implemented in Greece through a European-funded project.

“Tree-like seaweeds serve as important indicators of marine ecosystems’ health, particularly along undisturbed Mediterranean coastlines,” Salomidi explains. “Regrettably, we estimate that over 60% of their cover in reefs in Greece have been lost. This is primarily due to the proliferation of herbivorous sea urchins, which graze unchecked, hindering coral regeneration. Additionally, overabundant herbivorous fish, such as the invasive spinefoots, contribute to the problem.” Salomidi emphasizes the role of top predators, such as large fish, in maintaining the balance of ecosystems. “We’ve seen a drastic decline in these predators due to overfishing. Their absence disrupts the natural food chain, leading to ecosystem collapse.”

As awareness grows, efforts to restore marine ecosystems are becoming increasingly urgent. “We must recognize the vital role of these lions and wolves of the sea,” Salomidi urges. “Their absence leads to ecosystem collapse and the loss of marine forests.”

Marine forests

Seaweed forests are vital for preserving biodiversity, serving as essential habitats for various marine species. These underwater ecosystems support marine life by providing food, shelter and breeding grounds while also contributing to nutrient cycling, carbon sequestration and water purification.

A team led by Dr Annalisa Falace from the University of Trieste embarked on a mission several years ago to restore seaweed forests in Marine Protected Areas of Italy. Collaborating with the HCMR, the scientists aimed to address the alarming decline of underwater forests.

‘We estimate that over 60% of seaweed forests in Greece have been lost. This is partly due to the proliferation of herbivorous sea urchins, which graze unchecked, hindering natural regeneration,’ says researcher Maria Salomidi

Polytimi-Ioli Lardi, a doctoral candidate at the University of the Aegean and a research assistant at the HCMR, sheds light on their efforts. “The first experimental cultivation was carried out in 2021 at the HCMR facilities,” she states. “We faced various difficulties, but for a first attempt, we did quite well.”

Their proposal to restore underwater forests received funding from the European Union’s LIFE program under the title REEForest. The REEForest program aims to restore underwater Cystoseira forests in areas of Italy and Greece to enhance coastal biodiversity. These areas include protected marine zones around Italy’s Sinis Peninsula, Mal di Ventre island, Bergeggi and Cilento National Park, as well as Greece’s Gyaros island in the Aegean Sea.

“This year, we are cultivating a species of Cystoseira which used to be quite common in Greece,” Lardi explains. “The process involves collecting terminal segments of the algae and rinsing them thoroughly with filtered seawater.”

The spores are released onto ceramic tiles in tanks with seawater. “After two or three days, they begin to develop rhizoids, allowing the safe anchoring of the young individuals on the ceramic surfaces,” Lardi adds.

Scientist-divers collect branches of the algae Cystoseira. In the laboratory, they will use the fertilized seeds of the plant to grow them.

The small ceramic tiles remain under controlled conditions in the laboratory for approximately three weeks. “Subsequently, there are two options. Either you leave them for a few weeks on disks floating in the sea at a depth of about 3 meters, to achieve better growth outside the cramped conditions of the lab. Or, once they are ready, you transfer and secure the ceramic tiles to rocky coastal surfaces. This year, this aspect of the operation is scheduled to take place off Gyaros in mid-June, with the collaboration of the Central Aegean Management Unit of the Organization for the Protection of the Environment (NECCA),” Lardi concludes.

The project’s success hinges on meticulous monitoring. “The project sites will be continuously monitored in the coming years to evaluate the effectiveness of restoration measures,” Salomidi explains.

“Awareness and public outreach activities on the protection of marine biodiversity will also be implemented,” she says. As the initiative gains traction, it holds promise for the broader restoration of underwater forests in the Mediterranean. “Depending on the success of the actions, we will contribute to the development of guidelines to support national and European policies,” Salomidi concluded.


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