Rapid post-bloom resuspension in the northeastern Atlantic

Abstract

The importance of particulate matter input on the seafloor following spring bloom and of resuspension processes in middle and high latitudes of the north Atlantic ocean has been recently emphasized. However the possibility of the coupling between both processes until now, has not been reported. To study the fate of the particulate matter after its arrival on the bottom, a deep-sea observatory has been launched in the NEA (Nuclear Energy Agency) area of the northeastern Atlantic abyssal hill province. Time series of botton currents, near bottom particle concentration measurements and time lapse photographs were obtained from March to July 1988, while particulate matter fluxes were recorded with a sequential sediment trap. The most interesting results are the observation of a series of events starting with the arrival on the bottom of 5–10 mm aggregates following the spring bloom, their disaggregation within 2 weeks immediately followed by a rise of the near-bottom particle concentration, concomitant with the passage of a bottom current eddy. These observations illustrate how rapid disaggregation rates may lead to resuspension following high particulate matter input.