Site details

(lookup in gazetteer)
Flag of France
5 stars - Fully protected as a national park or Natura 2000 site by national legislation
LTBR Focal Site

Map type: Google Maps  SVG (dynamic)  Image (static)

Aerial view of the Northern basin Photo:

Synoptic description of site:

The bay of Brest constitutes a semi-enclosed coastal macrotidal ecosystem (surface: 180km˛) under the influence of both freshwater inputs from rivers and fast mixing exchange with waters from the Atlantic Ocean.

Extensive description of site:

The Bay of Brest is a semi enclosed area, shallow (average depth 5m) with all types of grounds ranging from muds to pebbles, together with a high salinity range (i.e. 0 to 36 PSU). Tidal range is high (7m), and the bay has some of the most extensive shores in Brittany.

Habitats present:
Seagrass bedsX

Description of fauna and flora:

Due to the great variety of soft and rocky bottoms in the bay, the species richness is very high. Also, the bay has the largest and probably richest maerl beds in France. The fauna and flora have been studied since the 19th century and thus are very well documented.

Human impact:

The area is under the influence urban and industrial effluents in its northern basin (20% of the total area) due to the presence of Brest conurbation (220,000 inhabitants). The southern basin is seasonally fished for scallops and for Venus. Heavy nutrient inputs (from agricultural origin) come from the large watershed of the two main rivers. Strong tidal currents however ensure renewal of the water sufficient to avoid eutrophication events or heavy pollution of the northern basin.


All facilities for marine biodiversity research are available, from research vessels, diving teams, fully equipped laboratories (University and IFREMER) and the Centre de Documentation de la Mer (France’s biggest marine library).

Available database and website:

The species inventory of the IUEM marine station is available as hardcopy, while a web site is under development ( The IFREMER website provides a database on contaminant concentrations in several biota.


Commitment and ongoing research:

The IUEM marine station has two research laboratories working on all aspects of marine biodiversity in the Bay of Brest (phytoplankton, zooplankton, marcroalgae, macrofauna, fishes). IFREMER laboratories lead ongoing survey programs in the area. The eastern part of the southern basin has been proposed as a Natura 2000 area. The REBENT project (national long term benthic assemblages survey) includes 6 stations in the bay of Brest.