Change in the Channel

The researchers embark on the Neomysis vessel to collect samples of seawater at two locations serving as reference points, one near the coast and the other off the Isle of Batz.

A first series of samples is taken 500 metres from the coast, at the point "Estacade." This natural environment is particularly sensitive to climate change and human activities. The first analyses date back to 1985.

In the offshore waters 5 km from the first reference point, the effects of human activities are less pronounced. Measurements taken here are more indicative of changes in the marine environment in the Western Channel, which are associated more particularly with climate change.

Using a Niskin bottle, the engineers sample seawater both at the surface and at a depth of 60 m.

The seawater samples are prepared on board for laboratory analysis. Several biogeochemical parameters will be measured with great precision: salinity, temperature, nutrients, etc.

The engineers use a net to take samples of phytoplankton, the concentration and diversity of which act as indicators of the ecological status of this environment.

At Roscoff, salinity and temperature have been monitored regularly since 1952. These data provide evidence of long-term changes.

In addition to the bimonthly manual data collection operations, automatic sensors have been placed under the “Astan” cardinal buoy located halfway between the coastal and open water sampling points.

The SOMLIT (Service d’Observation en Milieu LITtoral [Department for Observation of the Coastal Environment]) observation network includes nine other marine stations around the French coastline which carry out bimonthly measurements using the same protocols.

All the data acquired are made available in open access (OA) on the Internet, providing researchers around the world with reliable measurements for their studies. A regular temperature increase of several tenths of a degree has been observed since these measurements began.