• Coralligene Conservation

    Protecting Aegean Coralligenous


In the depths of the Greek Seas, between 70 to 250 meters, lie the oldest, most complex and productive marine ecosystems: coralligenous habitats. Corals that survive here today may exceed the age of 7000 years. Today, human activity puts their survival at great risk.

Coralligenous habitats thrive in the dimly lit mesophotic zone. They are one of the oldest, most complex and productive marine ecosystems within the Mediterranean Sea. However, they remain one of the most understudied and least protected habitats. They are truly “out of sight and out of mind”. The lack of enforcement of existing legislation for their conservation puts the survival of these highly diverse and ecologically important habitats at immense risk of irreversible destruction, mainly due to bottom trawling fisheries. 

Despite EU and international legal requirements, coralligenous habitats are at risk of being destroyed any moment by trawling activities, which are still considered “legal”. This is due to the national authorities of Greece and other Mediterranean countries not upholding their obligations to map and protect these threatened marine habitats. 

“Protecting Aegean Coralligenous” is one of the key long-term marine conservation actions of Archipelagos Institute, aiming to halt the ongoing destruction of these pristine habitats. It is carried out in collaboration with the international environmental organization Oceana, the Life Sciences Department of University of Essex, United Nations Regional Action Center for the Mediterranean (UNEP / MAP – SPA RAC) and the Laboratory of Physical Geography of the National and Kapodistrian University of Athens, with the support of the Pure Ocean Fund. The active involvement from local fishermen of the Aegean islands, through participatory GIS, is also invaluable for this important endeavour.

Research on the “Aegean Explorer” leads the coralligenous conservation work

Coralligenous Habitats

Coralligenous habitats are considered one of the most important biodiversity hotspots in the Mediterranean. Hosting over 1700 species, coralligenous assemblages provide key spawning grounds for commercial fish and invertebrates. Their structural heterogeneity allows assemblages of porifera, anthozoans, bryozoans, hydroids, and many other organisms to coexist.  

Classified by the EU as “reefs”, coralligenous assemblages are endemic to the Mediterranean. Made up of encrusting coralline algae, these structures act as a carbonate sediment builder and provide a habitat for many marine species. The formation of this calcareous environment can take thousands of years, creating a natural monument stemming from algal species such as Lithophyllum sp. and Mesophyllum sp.

With extremely slow-growth rates of less than 1mm/year, previous studies have dated reefs surpassing 7,000 years of age, rendering their destruction irreversible. Due to the slow growth rate and increasing anthropogenic impacts, coralligenous habitats are widely considered “vulnerable marine ecosystems”. Current distributional data covers only 30 percent of the Mediterranean coast, with most data representing depths between 10 and 50 metres. Therefore, reefs between 50 and 200 metres, those most common in the Aegean, are understudied and their distribution remains largely unknown. 

Highly biodiverse sponge-dominated coralligenous reef at 90m depth provide an essential habitat for lobsters



By using a multi-faceted approach, Archipelagos Institute of Marine Conservation is working to halt the unregulated destruction of these distinctive habitats through the combination of the following actions: 

The multi-faceted approach of Archipelagos Institute aims to directly link research with conservation

Coralligenous Habitat Mapping & Biodiversity Surveys:

Researchers onboard the “Aegean Explorer” for the ongoing mapping of coralligenous habitat

A key prerequisite for the effective management and conservation of these biodiversity hotspots is creating accurate maps for the entire Mediterranean region. It is impossible to enforce no-trawling zones without such maps; the most urgent measure needed to protect this vulnerable habitat. Current research never resulted in the necessary maps and only achieved (large-scale) data for selected areas in the Mediterranean Sea. The existing knowledge gaps on the distribution of this ecosystem are even more prominent outside Marine Protected Areas (MPA), in particular, the eastern Mediterranean Sea. 

Years of Archipelagos’ preliminary research and information exchange with local communities resulted in potential hotspots of coralligenous reefs, with an urgent need for mapping. After the identification of these potential hotspots, Archipelagos has designed and is applying a rapid-assessment mapping technique using multi-beam sonar, biomass scanner technology and Remotely Operated Vehicle (ROV) surveys to accurately locate the habitats across the Aegean Sea. This advanced technology provides valuable insight on the presence of any marine habitat on the seafloor. ROV data is used to validate the presence and classify the habitat types and taxonomy in-depth.  

As a biodiversity hotspot, a comprehensive ecological assessment is of crucial importance to truly understand what specific protection the habitats need. One of Archipelagos’ key objectives is to identify protected and vulnerable species within the coralligenous habitats. For such an understudied region, and in particular a highly understudied habitat, there is a high possibility of finding new or unclassified species. 

Law & Policy: Promoting Legislation Enforcement

The most pressing issue to address for coralligenous conservation is the immense damage caused by unregulated trawling fisheries, that is due to the ineffective conservation measures combined with poor habitat mapping. As an urgent priority, Archipelagos Institute of Marine Conservation is working towards the implementation and effective enforcement of ‘no-trawl zones’ to protect the coralligenous habitats from further destruction.

The results of the research conducted by Archipelagos Institute and its partners is being communicated with policymakers at a national, EU and international levels aiming to promote legislative and conservation efforts on a regional and Mediterranean scale. Our immediate target is to create the scientific and policy foundations for the establishment of the first no-trawl zones over coralligenous habitats in the Aegean Sea. 

A forest of black coral, Antipathella subpinnata located at 100 meters depth in the eastern Aegean Sea. Even though it is a a protected species, it is located within a “legal” trawling area!

Community Engagement & Citizen Science

The ongoing marine conservation efforts of Archipelagos Institute rely on the strong support from the local communities. The active role of local fishermen from the Aegean Islands is invaluable. For almost 15 years, Archipelagos has developed a relationship of mutual trust and cooperation; exchanging locational information with the joint aim of halting the destruction of coralligenous habitats, and other destructive fishing practices before it is too late. 

By using the local environmental knowledge of fishermen, we are able to locate and map the most intact coralligenous habitats at low-cost and low-risk via participatory GIS. Fishermen provide an invaluable source of information to avoid the high cost of traditional methodologies. This is particularly important when mapping the extensive and remote parts of our coastlines. Furthermore, participatory GIS helps to achieve a great level of community engagement and conservation awareness by improving trust through collaboration. 

Looking to further raise public awareness and engagement, Archipelagos aims to foster a shared sense of responsibility to protect these unique habitats for future generations. By developing an awareness raising campaign for the threats and need for protection of these fragile habitats, we will present findings at a  local, national, EU and international level. Using targeted articles, videos and posts in both mainstream media and social media, we intend to reveal the conservation value, unique beauty and threats of these fragile ecosystems.

The results of the research conducted by Archipelagos Institute and its partners is being communicated with policymakers at a national, EU and international levels aiming to promote legislative and conservation efforts on a regional and Mediterranean scale. Our immediate target is to create the scientific and policy foundations for the establishment of the first no-trawl zones over coralligenous habitats in the Aegean Sea.