Neuer¹, Susanne, Andrés Cianca², Maria-José Rueda², Octavio Llinás², Robert Davenport³, Tim Freudenthal³, Gerold Wefer³, Magdalena Santana-Casiano⁴ and Melchor González Dávila⁴

¹Arizona State University, Tempe, USA, E-mail: Susanne.neuer@asu.edu, ²Instituto Canario de Ciencias Marinas, Telde, Gran Canaria, Spain, ³University of Bremen, Geosciences, 28359 Bremen, Germany, and ⁴University of Las Palmas de Gran Canaria, Faculty of Marine Science, Gran Canaria, Spain

First seven years of biogeochemical data at the European time series station ESTOC

ESTOC (European Station for Time-Series in the Ocean, Canary Islands) is located 100 km north of the Canary Islands in the eastern boundary system of the subtropical North Atlantic gyre. Standard parameters of hydrography, nutrients, oxygen chlorophyll a and dissolved inorganic carbon have been measured at the station since 1994 in monthly intervals; monthly measurements of pCO₂ were added in 1996. Particle flux has been measured with moored particle traps at the station since 1991, and with surface tethered traps seasonally since 1995. Primary production was inferred from the in situ chlorophyll concentration by applying a bio-optical model.

Here we present data obtained at ESTOC from 1994 until 2000, focusing on the seasonality and interannual change of surface water processes and carbon export. In general, the seasonal cycle of phytoplankton biomass at the station is typical of a subtropical gyre station; a marked phytoplankton biomass maximum in winter follows the break-up of the seasonal thermocline in late fall. Chlorophyll levels in winter are around 0.4 mg l^-1, and in summer around 0.05 mg l^-1 in the surface. Yearly integrated primary production at ESTOC is around 12 mol C m^-2 yr^-1 and particulate C-export amounts to 0.2 mol C m^-2 yr^-1, determined both by surface-tethered traps at 200 m and moored sediment traps at 500 m. Net CO₂ fluxes at ESTOC are positive with an average value of 179 mmol CO₂ m^-2 yr^–1. We will estimate physical and biological components of the carbon balance at ESTOC using the available rates and total inorganic carbon variability determined at the station.