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The distribution of live benthic foraminifera (>63 μm) in box core samples from coarse sediments of the Ria de Vigo (NW Iberian margin) is mainly related to food availability and bottom current range. Live benthic foraminifera are dominated by small forms (63–125 μm). Faunal densities and diversity values suggest that very coarse substrates provide a favorable settlement for live benthic foraminifera. It is suggested that microalgae or bacterial biofilms that colonize shell surfaces are the main food resource for foraminifera. During upwelling events, the food supply to the bottom increases and the environment is colonized by opportunistic species. Moderate- to low-velocity bottom currents favor such pathways. The upwelling not only enhances the density of benthic foraminifera, but also allows the arrival of new species from the shelf. Attached forms are related to relatively high-velocity bottom currents and free living forms to moderate- to low-velocity bottom currents. Live benthic foraminifera inhabit a wide range of sediment depths and are not restricted to the uppermost centimeter. Under relatively high-velocity bottom current regimes, the vertical distribution of live benthic foraminifera is controlled by current strength. In coarse sediments, attached forms commonly considered strict epifaunal, and inhabiting above the disturbance depth, are considered “pseudoepifauna.” Below the disturbance depth, the sediment is not affected by currents and a “true” infauna is recognized.

High resolution benthic foraminiferal stable isotopes (δ18O, δ13C) and molecular biomarkers in the sediments are used here to infer rapid climatic changes for the last 8200 years in the Ría de Muros (NW Iberian Margin). Benthic foraminiferal δ18O and δ13C potentially register migrations in the position of the hydrographic front formed between two different intermediate water masses: Eastern North Atlantic Central Water of subpolar origin (ENACWsp) and subtropical origin (ENACWst). The molecular biomarkers in the sediment show a strong coupling between continental organic matter inputs and negative δ13C values in benthic foraminifera. The rapid centennial and millennial events registered in these records have been compared with two well known North Atlantic Holocene records from the subtropical Atlantic sea surface temperatures (SST) anomalies off Cape Blanc, NW Africa and the subpolar Atlantic (Hematite Stained Grains percentage, subpolar North Atlantic). Comparison supports a strong link between high- and low-latitude climatic perturbations at centennial–millennial time scales during the Holocene. Spectral analyses also points to a pole-to-equator propagation of the so-called 1500 yr cycles. Our results demonstrate that during the Holocene, the NW Iberian Margin has undergone a series of rapid events which are likely triggered at high latitudes in the North Atlantic and are rapidly propagated towards lower latitudes. Conceivably, the propagation of these rapid climatic changes involves a shift in atmospheric and oceanic circulatory systems., The authors acknowledge to the EU project HOLSMEER: Holocene Shallow Marine Environments of Europe (EVK2-CT-2000-00060) for providing samples and financial support, GRACCIE (Consolider-Ingenio, CDS 2007-00067); CONTOURIBER (CTM 2008-06399-C04-01/MAR) y Proxecto 08MDS036000PR (Xunta de Galicia). L.P. and P.D. also thank the EU Acces to Research Infrastructures Paleostudies Program (Geosciences Faculty, Bremen University, Germany) for providing us with analytical facilities, and to F. Lamy for all the help provided. L.P. acknowledges a fellowship from the Comer Abrupt Climate Change Foundation (USA). Thoughtful comments and discussion provided by P.G. Mortyn are greatly thanked. Also thanks to Antje Volker and an anonymous reviewer for very insightful comments that helped to improve the quality of this paper. This is LDEO contribution 7352.

High resolution benthic foraminiferal oxygen and carbon stable isotopes (?18O, ?13C) from core EUGC-3B are used here to infer rapid climatic changes for the last 8500 yr in the Ría de Muros (NW Iberian Margin). Benthic foraminiferal ?18O and ?13C potentially register migrations in the position of the hydrographic front formed between two different intermediate water masses: Eastern North Atlantic Central Water of subpolar origin (ENACWsp), and subtropical origin (ENACWsp). The isotopic records have been compared with two well established North Atlantic marine Holocene paleoceanographic records from low (Sea Surface Temperatures anomalies off Cape Blanc, NW Africa) and high latitudes (Hematite Stained Grains percentage, subpolar North Atlantic). This comparison clearly demonstrates that there is a strong link between high- and low-latitude climatic perturbations at centennial-millennial time scales during the Holocene. Spectral analyses also points at a pole-to-equator propagation of the so-called 1500 yr cycles. Our results demonstrate that during the Holocene, the NW Iberian Margin has undergone a series of cold episodes which are likely triggered at high latitudes in the North Atlantic and are rapidly propagated towards lower latitudes. Conceivably, the propagation of these rapid climatic changes involves a shift of atmospheric and oceanic circulatory systems and so a migration of the hydrographical fronts and water masses all along the North Atlantic area.

13 pages, 6 figures, 2 tables., The Tagus Prodelta (W Portugal) and the Muros Ría (NW Spain) are areas of high deposition rates registering high-resolution palaeoclimatic records for western Iberia. We compare the climatic conditions of the two areas over the last two millennia based on proxies of temperature (sea surface temperatures and oxygen isotopes), continental input (grain size, iron and magnetic susceptibility) and productivity (inorganic and organic carbon, carbon isotopes, benthic foraminifera and diatoms). Biogeochemical changes in the Tagus Prodelta reflect widely recognized North Atlantic climatic periods encompassing the Roman Period (AD 0-350), the Dark Ages (AD 400-700), the ‘Mediaeval Warm Period’ (MWP; AD 800-1200) and the ‘Little Ice Age’ (LIA; AD 1300-1750). The atmospheric North Atlantic Oscillation (NAO) drives the Tagus Prodelta multidecadal, long-term variability in precipitation-river input during cold periods (negative NAO) and marine upwelling during warmer periods (positive NAO), a scheme that is reversed in the Galician region. The Muros Ría shows only local hydrodynamics until AD 1150, including a ‘suboxic’ event in the inner Ría around AD 500-700. Since AD 1150 Atlantic warm upwelled waters have ventilated the outer Ría but only reach the inner Ría at AD 1750. The twentieth-century records are also interpreted as a reflex of the inverse NAO mode in both areas, resulting in amplification of the LIA biogeochemical water conditions. Centennial-scale solar activity appears to be another important forcing mechanism (or the only one, if solar activity drives the NAO and ‘Bond-cycles’) behind changes in the hydrography of the Tagus Prodelta, and primary production, bottom ventilation and organic carbon degradation in the Muros Ría., We are grateful to participants and crews of Discovery 249, Poseidon PALEO 1, and B/O Mytilus cruises, and for laboratory technical assistance in grain size, LECO, isotopes, foraminifera and diatoms at the INETI-Laboratory of Marine Geology. Thanks to C. Kissel for the magnetic susceptibility measurements in Gif-sur-Yvette, to M. Siegl for isotope measurements and the ARI-Program at the University of Bremen, to E. Salgueiro and 5. Vaqueiro for XRF measurements at the Bremen Core Repository, to J. Heinemeier for helpful discussions during the construction of age models, to A. Ferreira for critical data discussion and A. Voelker for comments on the manuscript. The comments of an anonymous reviewer helped to improve the final version of this paper. Financial support was provided by EU project HOLSMEER (EVK2-CT-2000-00060). T. Rodrigues was supported by the Fundação para a Ciéncia e Tecnologia, INGMAR project.