Réseau de surveillance benthique – Région Bretagne. Approche sectorielle subtidale : Identification et caractérisation des habitats benthiques du secteur Trégor-Goëlo

In 2000 Ifremer launched and coordinated the development of a monitoring strategy for the REBENT network (REseau BENThique) in order to assess the aftermath of the “Erika” oil spill which took place in December 1999. Its aim is to provide consistent baseline knowledge on coastal benthic habitats, as well as to develop a monitoring tool that detects changes at various spatial and temporal scales. Sector-based seabed habitat mapping in shallow water (< 50 m deep), is currently being conducted throughout Brittany's coastal waters using a combination of geoacoustic marine systems together with ground-truthing using biological grab sampling and seabed observations. Due to the extended area, the overlap of soft and rocky bottoms, and contrasting hydrological conditions, the region of Tregor-Goelo is characterized by a mosaic of seabed habitats which host highly diversified fauna and flora. Six major soft-bottom macrofaunal communities were identified from 19 sampling stations. Detailed mapping of their distribution was achieved by means of morphosedimentary analyses based on a combination of remote sensing geoacoustic systems (multibeam echosounder and sidescan sonar), grab samplings and video observations. If at a regional scale, the description of benthic populations in the western Channel was made by Cabioch in 1968, the coastal area of Tregor-Goelo did not have so far been mapped for benthic habitats.