Temperature effects on carbon-specific respiration rate and sinking velocity of diatom aggregates – potential implications for deep ocean export processes

• Published in: Biogeosciences Vol. 10; no. 6; pp. 4073 - 4085
• Main Authors: Iversen, M. H, Ploug, H
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 20.06.2013; Copernicus Publications
• Subjects: Bacillariophyceae; Earth and Related Environmental Sciences; exopolymer particles tep; Exports; fecal pellets; Geovetenskap och miljövetenskap; hydrostatic-pressure; interannual variability; marine snow; microbial-degradation; nw mediterranean sea; organic-carbon; pelagic environment; sargasso sea
• ISSN: 1726-4189; 1726-4170; 1726-4189
• DOI: 10.5194/bg-10-4073-2013

Most deep ocean carbon flux profiles show low and almost constant fluxes of particulate organic carbon (POC) in the deep ocean. However, the reason for the non-changing POC fluxes at depths is unknown. This study presents direct measurements of formation, degradation, and sinking velocity of diatom aggregates from laboratory studies performed at 15 °C and 4 °C during a three-week experiment. The average carbon-specific respiration rate during the experiment was 0.12 ± 0.03 at 15 °C, and decreased 3.5-fold when the temperature was lowered to 4 °C. No direct influence of temperature on aggregate sinking speed was observed. Using the remineralisation rate measured at 4 °C and an average particle sinking speed of 150 m d−1, calculated carbon fluxes were similar to those collected in deep ocean sediment traps from a global data set, indicating that temperature plays a major role for deep ocean fluxes of POC.