Lemnos: The blue lungs of the Aegean Sea


















The northeastern part of Lemnos where the Natura 2000 site: Chortarolimni - Limni Alyki kai Thalassia periochi (GR4110001) is situated, extends beyond the coastline and well into the North Aegean Sea. The site covers an area of 183.13 km², of which 117.92 km² are attributed to habitat 1120 (Posidonia oceanica), making it one of the largest cohesive meadows of Posidonia in Greece and probably its greatest marine carbon sink. Previous mapping efforts in the general area indicate that the meadows expand outside the protected area surrounding the whole island and cover more than 250 km² (Traganos et al., 2018). Lemnos holds a great biodiversity and this feature is probably attributed to the fact that intensive fishing doesn’t occur in the area the past ten years. Given the abundance and variety the site sustains, suspicions that assign it as an important area for sea turtles and seabirds have some ground. The combination of the last two statements results in an area with high potential for conservation actions. Local stakeholders are very active and motivated by all that concerns the safeguarding of the site, so key actions have been taken to adopt management measures.

Name: Limnos | Chortarolimni - Limni Alyki kai Thalassia periochi
Natura 2000 site code: GR4110001
Location: North Aegean Sea
Coverage: 566,97 km²


Key traits of the area:

In 2022 iSea, visited Northeast Lemnos and recorded the marine biodiversity, the ichthyofaunal biomass and the conservation status of P. oceanica, mapped the meadows and estimated its blue carbon potential. Apart from the research activities, iSea also advocated for the adoption of management measures in the area, partnering with key stakeholders in a regional and national level.

Regarding the habitat mapping, a satellite multispectral image of 3m resolution was employed to map the designated area of interest and a random forest algorithm was applied to make the mapping more detailed and accurate. The analyses resulted in a mosaic of 83.72 km² spreading almost beyond 20 km from the coast.

The rich local biodiversity of the area was also documented and comprised of several fish species, marine phanerogams (other than Posidonia), sea algae, sponges, echinoderms, molluscs, marine mammals, and seabirds. In total, 59 marine organisms were recorded, belonging to 13 different taxa.

For the health assessment of the meadow, non-invasive techniques were used. P. oceanica leaves of 1.2m were observed in depth ranging between 4-15m. The overall sight of the meadow exhibits between a “moderate status” and a “good status” based on the quadrat survey which resulted in a variation of shoot density from 170-595.

The total blue carbon sequestered in the P. oceanica meadow mapped in Northeastern Lemnos was estimated at 274,891.81 MgC for the total area and 32.83 Mgc/ha.

Lastly, the final report concerning the area and the threats it may face were sent to the Ministry of Environment and Energy and shared with NECCA which is responsible for the protection and preservation of such types of sites.

You can find the project's report below: