CANYON HEADS AND RIVER PLUMES: HOW MIGHT THEY INFLUENCE NERITIC PLANKTONIC FORAMINIFERA COMMUNITIES IN THE SE BAY OF BISCAY?

The present study discusses the distribution of living planktonic foraminifera (LPF) in a neritic environment from the SE Bay of Biscay. Four sites, located at the head of Capbreton Canyon and near the Adour River mouth, were sampled during four cruises between June 2006 and July 2008. Each site was sampled with a plankton net (>100 mu m) to characterize the LPF communities. The four onshore stations are here compared to three offshore stations located along a bathymetric transect on the Plateau des Landes to document the influence of submarine canyon bathymetry and river input on LPF communities. Five major species were observed: Globigerina bulloides, Globigerinella calida-G. bulloides complex, Neogloboquadrina pachyderma dextral, Globorotalia inflata, and Turborotalita quinqueloba. Late spring (mid-June 2006) standing stocks showed a decreasing trend toward the coast, whereas fall (late November 2007) and summer (mid-July 2008) standing stocks showed higher values at the canyon head and onshore stations. High standing stocks dominated by specimens from the G. calida-G. bulloides complex were recovered in late November 2007 at neritic stations and could be related to upwelling and/or strong tidal currents in the submarine Capbreton Canyon. Their distribution and production in the SE Bay of Biscay is affected by the Adour River turbidity discharge and also by mesoscale upwelling events induced around the Capbreton Canyon head.