Alkenones and SST of surface sediments (Appendix)

We have analysed alkenones in 149 surface sediments from the eastern South Atlantic in order to establish a sediment-based calibration of the U37K' paleotemperature index. Our study covers the major tropical to subpolar production systems and sea-surface temperatures (SST's) between 0° and 27°C. In order to define the most suitable calibration for this region, the U37K' values were correlated to seasonal, annual, and production-weighted annual mean atlas temperatures and compared to previously published culture and core-top calibrations. The best linear correlation between U37K' and SST was obtained using annual mean SST from 0 to 10 m water depth (U37K' = 0.033 T + 0.069, r**2 = 0.981). Data scattering increased significantly using temperatures of waters deeper than 20 m, suggesting that U37K' reflects mixed-layer SST and that alkenone production at thermocline depths was not high enough to significantly bias the mixed-layer signal. Regressions based on both production-weighted and on actual annual mean atlas SST were virtually identical, indicating that regional variations in the seasonality of primary production have no discernible effect on the U37K' vs. SST relationship. Comparison with published core-top calibrations from other oceanic regions revealed a high degree of accordance. We, therefore, established a global core-top calibration using U37K' data from 370 sites between 60°S and 60°N in the Atlantic, Indian, and Pacific Oceans and annual mean atlas SST (0-29°C) from 0 m water depth. The resulting relationship (U37K' = 0.033 T + 0.044, r**2 = 958) is identical within error limits to the widely used E. huxleyi calibrations of and attesting their general applicability. The observation that core-top calibrations extending over various biogeographical coccolithophorid zones are strongly linear and in better accordance than culture calibrations suggests that U37K' is less species-dependent than is indicated by culture experiments. The results also suggest that variations in growth rate of algae and nutrient availability do not significantly affect the sedimentary record of U37K' in open ocean environments.

Survey bottom trawl data of Micromesistius poutassou (blue whiting) in Bay of Biscay and Celtic Sea from the EVHOE time series (1997-2011)

Data were collected during various groundfish surveys carried out by IFREMER from October to December between 1997 and 2011, on the eastern continental shelf of the Bay of Biscay and in the Celtic Sea (EVHOE series). The sampling design was stratified according to latitude and depth. A 36/47 GOV trawl was used with a 20 mm mesh codend liner. Haul duration was 30 minutes at a towing speed of 4 knots. Fishing was restricted to daylight hours. Catch weights and catch numbers were recorded for all species and body size measured. The weights and numbers per haul were transformed into abundances per km**2 by considering the swept area of a standard haul (0.069 km**2).