Multibeam and seismic survey, physical oceanography, and sea-bottom videos from the Bay of Biscay

We report the northernmost and deepest known occurrence of deep-water pycnodontine oysters, based on two surveys along the French Atlantic continental margin to the La Chapelle continental slope (2006) and the Guilvinec Canyon (2008). The combined use of multibeam bathymetry, seismic profiling, CTD casts and a remotely operated vehicle (ROV) made it possible to describe the physical habitat and to assess the oceanographic control for the recently described species Neopycnodonte zibrowii. These oysters have been observed in vivo in depths from 540 to 846 m, colonizing overhanging banks or escarpments protruding from steep canyon flanks. Especially in the Bay of Biscay, such physical habitats may only be observed within canyons, where they are created by both long-term turbiditic and contouritic processes. Frequent observations of sand ripples on the seabed indicate the presence of a steady, but enhanced bottom current of about 40 cm/s. The occurrence of oysters also coincides with the interface between the Eastern North Atlantic Water and the Mediterranean Outflow Water. A combination of this water mass mixing, internal tide generation and a strong primary surface productivity may generate an enhanced nutrient flux, which is funnelled through the canyon. When the ideal environmental conditions are met, up to 100 individuals per m² may be observed. These deep-water oysters require a vertical habitat, which is often incompatible with the requirements of other sessile organisms, and are only sparsely distributed along the continental margins. The discovery of these giant oyster banks illustrates the rich biodiversity of deep-sea canyons and their underestimation as true ecosystem hotspots.

Planktic foraminiferal turnover across the Paleocene-Eocene transition in the Bay of Biscay, North Atlantic

Planktic foraminifera across the Paleocene-Eocene transition at DSDP Site 401 indicate that the benthic foraminiferal mass extinction occurred within Subzone P 6a of Berggren and Miller (1988), or PS of Berggren et al. (1995) and coincident with a sudden 2.0? excursion in 6r3C values. The benthic foraminiferal extinction event (BFEE) and Sr3C excursion was accompanied by a planktic foraminiferal turnover marked by an influx of warm water species (Morozovella and Acarinina), a decrease in cooler water species (Subbotina), a sudden short-term increase in low oxygen tolerant taxa (Chiloguembelina), and no significant species extinctions. These faunal changes suggest climatic warming, expansion of the oxygen minimum zone, and a well stratified ocean water column. Oxygen isotope data of the surface dweller M. subbotina suggest climate warming beginning with a gradual 0.5? decrease in delta180 in the 175 cm preceding the benthic foraminiferal extinction event followed by a sudden decrease of 1? (4°C) at the BFEE. The delta13C excursion occurred over 27 cm of sediment and, assuming constant sediment accumulation rates, represents a maximum of 23 ka. Recovery to pre-excursion delta13C values occurs within 172 cm, or about 144 ka. Climate cooling begins in Subzone P 6c as indicated by an increase in cooler water subbotinids and acarininids with rounded chambers and a decrease in warm water morozovellids.

Stomach content records of albacore (Thunnus alalunga) and bluefin tuna (Thunnus thynnus) in the North Atlantic Drift Region focusing on the Bay of Biscay between 2004 and 2011

The tuna stomach database from AZTI-Tecnalia corresponds to 7 years of sampling from 2004 to 2011. Due to the absence of continuity in the different projects dealing with the feeding ecology of tunas, the sampling could not be performed every year for both species, and no sample was collected in 2008. However, the fish stomach content record contents composition - by prey weight - of 1525 albacore caught in the Bay of Biscay and surrounding waters of the North Atlantic Drift Region in 2005 (n=397), 2006 (n=196), 2007 (n=37), 2009 (n=95), 2010 (n=566) and 2011 (n=234) ; and of 686 bluefin tunas caught in the Southeastern Bay of Biscay in 2004 (n=32), 2005 (n=36), 2006 (n=3), 2009 (n=257), 2010 (n=233) and 2011 (n=125). Samples have been obtained from scientific research surveys (using a variety of different fishing gears), from commercial fisheries catches, from individual fish voluntarily sampled by recreational fishermen and from fish accidentally stranded on coastlines. Each predator is identified by an ID and its length and wet weight are given. In case the wet weight could not be measured, it was estimated through a length-weight relationship equation and is indicated in the comment for the Predator mass column. The total weight of each prey is given, as well as the weight of each prey taxonomic group in each stomach.

Predominance of heavily calcified coccolithophores at low CaCO3 saturation during winter in the Bay of Biscay

Coccolithophores are an important component of the Earth system, and, as calcifiers, their possible susceptibility to ocean acidification is of major concern. Laboratory studies at enhanced pCO2 levels have produced divergent results without overall consensus. However, it has been predicted from these studies that, although calcification may not be depressed in all species, acidification will produce "a transition in dominance from more to less heavily calcified coccolithophores" [Ridgwell A, et al., (2009) Biogeosciences 6:2611-2623]. A recent observational study [Beaufort L, et al., (2011) Nature 476:80-83] also suggested that coccolithophores are less calcified in more acidic conditions. We present the results of a large observational study of coccolithophore morphology in the Bay of Biscay. Samples were collected once a month for over a year, along a 1,000-km-long transect. Our data clearly show that there is a pronounced seasonality in the morphotypes of Emiliania huxleyi, the most abundant coccolithophore species. Whereas pH and CaCO3 saturation are lowest in winter, the E. huxleyi population shifts from <10% (summer) to >90% (winter) of the heavily calcified form. However, it is unlikely that the shifts in carbonate chemistry alone caused the morphotype shift. Our finding that the most heavily calcified morphotype dominates when conditions are most acidic is contrary to the earlier predictions and raises further questions about the fate of coccolithophores in a high-CO2 world.