Sinking particle properties from polyacrylamide gels during the KErguelen Ocean and Plateau compared Study (KEOPS): Zooplankton control of carbon export in an area of persistent natural iron inputs in the Southern Ocean

• Published in: Limnology and Oceanography
• Main Authors: Ebersbach, F, Trull, T
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society of Limnology and Oceanography 2008
• Subjects: Earth Sciences; Oceanography; Chemical Oceanography; Kerguelen; Southern Ocean
• Online Access: http://aslo.org; https://doi.org/10.4319/lo.2008.53.1.0212; http://ecite.utas.edu.au/54193

The Kerguelen ocean and plateau compared study (KEOPS) examined the origin of elevated phytoplanktonbiomass in naturally iron-fertilized waters over the Kerguelen plateau during midsummer (JanuaryFebruary2005). We report sinking particle characteristics determined from image analysis of thousands of individualparticles collected in viscous polyacrylamide gels placed in free-drifting sediment traps at two sites: a highphytoplankton biomass site over the central plateau (A3) and a moderate biomass site at its periphery (C5). Theparticles were divided into three types (1) oval fecal pellets, (2) cylindrical fecal pellets, and (3) aggregates. Theaggregates were most abundant and mainly consisted of agglomerations of the cylindrical fecal pellets.Conversion of the pellet and aggregate volumes to carbon contents suggests export fluxes of 5060 mg C m22 d21at 100-m depth, in reasonable agreement with independent estimates from carbon and 234Th measurements. Ourobservation that the majority of the particle flux was processed through the heterotrophic foodweb contrasts withthe results of artificial iron-fertilization experiments and with models for export from productive diatomdominatedwaters that emphasize direct export of phytoplankton detritus. The KEOPS results may offer moreappropriate scaling for the response of ecosystem structure and carbon export to persistent iron fertilization in theSouthern Ocean.