Benthic primary production and mineralization in a High Arctic fjord: in situ assessments by aquatic eddy covariance

Marine Ecology Progress Series

Mikael K. Sejr¹  Karl M. Attard¹  Kasper Hancke¹  Ronnie N. Glud¹ 

关键词: Benthic primary production;    Carbon cycling;    Arctic;    Aquatic eddy covariance;    Benthic macrofauna;   

DOI  :  10.3354/meps11780

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: Coastal and shelf systems likely exert major influence on Arctic Ocean functioning, yet key ecosystem processes remain poorly quantified. We employed the aquatic eddy covariance (AEC) oxygen (O₂) flux method to estimate benthic primary production and mineralization in a High Arctic Greenland fjord. Seabed gross primary production (GPP) within the 40 m deep photic zone was highest at 10 m (29 mmol O₂ m^-2 d^-1) and decreased to 5 mmol O₂ m^-2 d^-1 at 40 m, while nighttime community respiration (CR) ranged from 11 to 25 mmol O₂ m^-2 d^-1. CR decreased to ~2.5 mmol O₂ m^-2 d^-1 at 80 m and remained constant with further depth. Fauna activity accounted for ~50% of the CR at depths ≤60 m but was <15% at depths ≥80 m. Benthic GPP and CR were comparable when scaled to the outer fjord area ≤40 m depth (2.7 and 3.1 t C d^-1), and here the seabed was twice as important as the pelagic compartment for primary production. However, when scaled to the entire outer fjord area of which 80% is >40 m, benthic GPP was 26% of the pelagic production. CR was 2-fold higher than GPP over this region (5.7 t C d^-1) and thus net heterotrophic. By scaling AEC-derived Arctic benthic GPP to the entire Arctic Ocean using modelled seabed light data, we estimate an annual Arctic Ocean benthic GPP of 11.5 x 10⁷ t C yr^-1. On average, this value represents 26% of the Arctic Ocean annual net phytoplankton production estimates. This scarcely considered component is thus potentially important for contemporary and future Arctic ecosystem functioning.

【 授权许可】

Unknown