Formicula island: A tiny stronghold of biodiversity in the Ionian Sea















Formicula (or Fermiculo as the locals call it) is a small uninhabited island in the Inner Ionian Archipelago, characterised by the extended presence of Posidonia oceanica meadows and strong presence of marine megafauna species and seabirds, with the islet considered as an “Important Marine Mammal Area” (IMMA). Due to its natural wealth, Formicula suffers from extensive boating tourism activities, as well as illegal, unregulated and unreported fishing, which greatly disturb its habitats and biodiversity.

Name: Formicula (Inner Ionian Archipelago)

Natura 2000 site code: GR2220003 

Location: Ionian Sea

Coverage: 53.3 km²

Key traits of the area:

In 2022 iSea, visited Formicula twice 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.

In total, 0.63 km² of cohesive meadows were mapped surrounding the island of Formicula and its shoals, extending below 35m of depth. In addition, 80 different marine organisms were recorded and identified, belonging in 20 different taxa and providing proof of a very rich biodiversity which apart from fish, between them two non-indigenous species, includes marine phanerogams (other than Posidonia), sea algae, sponges, echinoderms, molluscs, and marine mammals. 

The conservation status of the meadows based on the Conservation Index (CI) was estimated at 0.98 and assessed as “very good state” in the sampled locations. Conversely, the shoot density and total image of the meadows portray a different picture, with shoot density ranging from 170-180. More research is needed to draw concrete conclusions and link the state of the meadows with possible stressors such as eutrophication and/or pollution. Finally, it is worth noting that fragmentation due to uncontrolled anchorage was observed at the site, as well as abandoned fishing gear.

The total blue carbon sequestered in the P. oceanica meadows of Formicula was estimated to be 2,512.63 MgC or 39.88 Mgc/ha. This value is the first estimate for blue carbon in the Inner Ionian Archipelago; however, more research and samplings are needed to have accurate conclusions.

Lastly, iSea in collaboration with Tethys Research Institute, Municipality of Lefkada, and Blue Marine Foundation created a joint letter to take immediate protection measures on the Formicula island and the reef near it as it is a very important area for the regional marine ecosystem. The proposed measures have been introduced in the Special Environmental Study (SES) concerning the Natura 2000 sites of the Ionian and Western Greece.

You can find the project’s reports below: