TY - JOUR
T1 - Long-Term Changes of Particle Flux in the Canary Basin Between 1991 and 2009 and Comparison to Sediment Trap Records Off Mauritania
AU - Fischer, Gerhard
AU - Neuer, Susanne
AU - Ramondenc, Simon
AU - Müller, Thomas J.
AU - Donner, Barbara
AU - Ruhland, Götz
AU - Ratmeyer, Volker
AU - Meinecke, Gerrit
AU - Nowald, Nico
AU - Klann, Marco
AU - Wefer, Gerold
N1 - Funding Information:
We dedicate this contribution to the memory of our friend Dr. Helge Meggers whose contributions to paleoceanography and microfossil observations off NW Africa have been invaluable. We acknowledge the guidance of the expeditions with RV Meteor and RV Poseidon, in the later years by Tim Freudenthal. We are indebted to ships’ crews and masters of the relevant cruises (Supplementary Material). For discussion, we thank Oscar Romero, Holger Kuhlmann, and Gesine Mollenhauer. Thanks to colleagues from former ICBM in Telde, Gran Canaria (now PLOCAN) for the support during and before the ships’ cruises. Establishing such a long time series of fluxes and water column studies at ESTOC and off Cape Blanc was only possible due to a long-term funding by the Deutsche Forschungsgemeinschaft through the SFB 261, the RCOM, and the MARUM Excellence Cluster “The Ocean in the Earth System” at Bremen University. Further, the long financial support for the technologicl innovations and current meter moorings by the BMBF (also through JGOFS) and the EU is greatly acknowledged. We thank the three reviewers for helpful comments and the editorial staff of “Frontiers.”
Publisher Copyright:
© Copyright © 2020 Fischer, Neuer, Ramondenc, Müller, Donner, Ruhland, Ratmeyer, Meinecke, Nowald, Klann and Wefer.
PY - 2020/7/14
Y1 - 2020/7/14
N2 - Eastern Boundary Upwelling Ecosystems (EBUEs) are associated with high biological productivity, high fish catch and they highly contribute to marine carbon sequestration. Whether coastal upwelling has intensified or weakened under climate change in the past decades is controversially discussed and different approaches (e.g., time-series of chlorophyll, wind, sea surface temperature, modeling experiments) have been considered. We present a record of almost two decades of particle fluxes (1991–2009) from ca. 600 to 3100 m water depth in the Canary Basin at site ESTOC (European Station for Time series in the Ocean Canary Islands; ca. 29°N, 15°30.W, ca. 3600 m water depth), located in the offshore transition zone of the northern Canary Current-EBUE. We compare these flux records with those measured at a mesotrophic sediment trap site further south off Cape Blanc (Mauritania, ca. 21°N). The deep ocean fluxes at ESTOC in ca. 3 km recorded the evolution of the coastal Cape Ghir filament (30–32°N, 10–12°W) due to lateral advection of particles, whereas the upper water column sediment traps in ca. 1 km reflected the oligotrophic conditions in the overlying waters of ESTOC. We observed an increased emphasis in spring-time fluxes since 2005, associated with a change in particle composition, while satellite chlorophyll biomass did not show this pattern. Due to its northern location in the CC-EBUEs, spring biogenic fluxes at ESTOC provide a better relationship to the forcing of the North Atlantic Oscillation than those recorded further south off Cape Blanc. Off Cape Blanc, deep fluxes showed the best overlap with the deep ESTOC fluxes during the spring season before 2005. On the long-term, both chlorophyll and particle fluxes showed an increasing trend at ESTOC which was not observed further south at the mesotrophic Cape Blanc site. This might indicate that, depending on their location along the NW African margin, coastal upwelling systems react differently to global change.
AB - Eastern Boundary Upwelling Ecosystems (EBUEs) are associated with high biological productivity, high fish catch and they highly contribute to marine carbon sequestration. Whether coastal upwelling has intensified or weakened under climate change in the past decades is controversially discussed and different approaches (e.g., time-series of chlorophyll, wind, sea surface temperature, modeling experiments) have been considered. We present a record of almost two decades of particle fluxes (1991–2009) from ca. 600 to 3100 m water depth in the Canary Basin at site ESTOC (European Station for Time series in the Ocean Canary Islands; ca. 29°N, 15°30.W, ca. 3600 m water depth), located in the offshore transition zone of the northern Canary Current-EBUE. We compare these flux records with those measured at a mesotrophic sediment trap site further south off Cape Blanc (Mauritania, ca. 21°N). The deep ocean fluxes at ESTOC in ca. 3 km recorded the evolution of the coastal Cape Ghir filament (30–32°N, 10–12°W) due to lateral advection of particles, whereas the upper water column sediment traps in ca. 1 km reflected the oligotrophic conditions in the overlying waters of ESTOC. We observed an increased emphasis in spring-time fluxes since 2005, associated with a change in particle composition, while satellite chlorophyll biomass did not show this pattern. Due to its northern location in the CC-EBUEs, spring biogenic fluxes at ESTOC provide a better relationship to the forcing of the North Atlantic Oscillation than those recorded further south off Cape Blanc. Off Cape Blanc, deep fluxes showed the best overlap with the deep ESTOC fluxes during the spring season before 2005. On the long-term, both chlorophyll and particle fluxes showed an increasing trend at ESTOC which was not observed further south at the mesotrophic Cape Blanc site. This might indicate that, depending on their location along the NW African margin, coastal upwelling systems react differently to global change.
KW - Canary Current
KW - Cape Blanc
KW - ESTOC
KW - biological pump
KW - climate change
KW - particle flux
KW - seasonality
KW - sediment traps
UR - http://www.scopus.com/inward/record.url?scp=85088795140&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85088795140&partnerID=8YFLogxK
U2 - 10.3389/feart.2020.00280
DO - 10.3389/feart.2020.00280
M3 - Article
AN - SCOPUS:85088795140
SN - 2296-6463
VL - 8
JO - Frontiers in Earth Science
JF - Frontiers in Earth Science
M1 - 280
ER -