Impact of a warm anomaly on export fluxes of biogenic matter in the eastern Fram Strait

• Main Authors: Lalande, Catherine, Bauerfeind, Eduard, Nöthig, Eva-Maria, Beszczynska-Möller, Agnieszka
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Fram Strait; Sea ice
• Online Access: https://epic.awi.de/id/eprint/30559/; https://hdl.handle.net/10013/epic.39535

As part of the HAUSGARTEN long-term observatory, sediment trap deployments were carried out before, during, and after the anomalously warm Atlantic Water inflow observed from 2005 to 2007 in the eastern Fram Strait. Downward export of particulate organic carbon (POC), zooplankton fecal pellet carbon (FPC), and biogenic particulate silica (bPSi) were measured from August 2002 to June 2003 and from July 2004 to July 2008 to indirectly assess the impact of the warm anomaly on phytoplankton and zooplankton production in the region. Lower and less frequent bPSi and FPC fluxes were observed during most of the warm anomaly period, indicating a decrease in the production of diatoms and fecal pellets under warmer conditions. The simultaneous increases and decreases in bPSi and FPC export suggest that zooplankton production was indirectly affected by an increase of water temperature through a change in diatom production. Biogenic silica and fecal pellet export always increased in the presence of ice cover in the sediment trap area, even during the warm anomaly period, suggesting that sea ice is a key factor influencing the frequency of export events in the eastern Fram Strait. Very low ice concentrations in 2005 and 2006 may partly be due to the warm anomaly, although solar radiation and ice drift due to wind stress also govern ice cover extent in the region. Nevertheless, the long-term measurements of export fluxes in the eastern Fram Strait showed that warmer conditions resulted in an intensified retention of bPSi and fecal pellets in the upper water column when associated with a reduction in ice cover.