Biodiversity on the islands of Ouessant and Molène is rich and unique. The importance of some coastal habitats is recognized by the European Union, and many species of high natural heritage value can be found there, including the Marsh Harrier, Dartford Warbler, Red-billed Chough, Land Quillwort, and Least Adder’s Tongue. The islands are a stopover and nesting place for sea birds (storm petrels). The beaches are home to a wide variety of algal and benthic species. A colony of grey seals and a sedentary group of bottlenose dolphins also call the Molène archipelago home.

The current challenge is to maintain balance in the various ecosystems of the Biosphere reserve, in the face of developing human activities on the larger islands and at sea.

On Ouessant Island, rural activities like small-scale cultivation and livestock breeding have almost disappeared. The Reserve strives to preserve its characteristic landscapes – moors criss-crossed with dry stone walls (which protect crops from the wind, sea spray, and from livestock left to graze freely on the hillsides over the winter months), and dotted with small stone shelters.
On the Île de Molène, the tradition of commercial fishing remains small-scale.

Traditional algae production in the Molène archipelago has been modernized, and is the largest algae “field” in Europe harvested for use as raw materials in nutritional and cosmetic products.

Today, the main economic activity of the islander population is tourism. This results in significant population growth over the summer months, which has consequences for the environment.