Site details

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5 stars - Fully protected as a national park or Natura 2000 site by national legislation
LTBR Focal Site

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Glenan Islands from the east. Photo: D Rault

Synoptic description of site:

South Britanny France 10 miles south off Concarneau The GLENAN archipelago is constituted of a series of rocky islands covering approximatively 35 km2 surrounding sandy zones . This lagoon-like structure is unique on Atlantic coast.

Extensive description of site:

The Glenan Archipelago comprises a series of rocky granite islands covering approximatively 50 km2 surrounded by sandy zones, and is situated 17km south of Concarneau Bay (South Britanny). The island circle delimits a small shallow inner sea. This “lagoon” type of landscape is unique on the NE Atlantic coast, and results in a variety of degrees of water agitation that determines a complex patchwork of sedimentary and rocky bottoms.

Habitats present:
Littoral XX
Sublittoral XX
Seagrass beds 

Description of fauna and flora:

The inventory of the submarine rocky flora and fauna of the Glenan Islands demonstrates southern influences with, in particular, a dominance of Saccorhiza bulbosa in the upper levels of laminarians and an abundance of fields of Cystoseira sp. in N.E. and inside the archipelago. The archipelago presents a very large variety of facies within the biocenose of laminarians. Owing to the transpency of the water on the South and West borders of the archipelago, the laminarian biocenose extends below 26m. The northern part of the archipelago is more sheltered with a lesser water clarity.

Pristiness: High


The Glenan Islands are sufficiently far from the continental coast for being protected of the major anthropogenic effects. No important industry over 100km.

Human impact:

The archipelago is practically devoid of permanent human inhabitants (the number never exceeds 5-10). There is some tourist activity (mainly sailing) in summer, but practically no pollution. Commercial fishing is diverse in the area, but only small boats (<12 m) can operate and trawling is prohibited. Dredging occurs locally (maërl beds).


Only one main island is accessible by public transport (summer). All islands are accessible from the mainland (Concarneau) by local boats. The distance from the Islands to the fully equipped marine biology station in Concarneau is approximately 17km.

Available database and website:

Databases of locally found marine species are still in preparation. Website:


Commitment and ongoing research:

The Glenan site has been studied regularly for more than 120 years and is major focus for the Concarneau Marine Station’s programmes and regional networks of subtidal survey. The Marine Biology Station of the Muséum National d’Histoire Naturelle (Concarneau) has an agreed science plan and specifically allocated budget for biodiversity work on the Archipelago.

Additional Information:

A more detailed description of the area and extensive list of references are available as hard copies.