Seasonal ecosystem metabolism across shallow benthic habitats measured by aquatic eddy covariance.

Abstract

Shallow benthic habitats are hotspots for carbon cycling and energy flow, but metabolism (primary production and res-piration) dynamics and habitat-specific differences remain poorly understood. We investigated daily, seasonal, andannual metabolism in six key benthic habitats in the Baltic Sea using ~ 2900 h of in situ aquatic eddy covariance oxygenflux measurements. Rocky substrates had the highest metabolism rates. Habitat-specific annual primary productionper m2 was in the order Fucus vesiculosus canopy > Mytilus trossulus reef > Zostera marina canopy > mixed macrophytescanopy > sands, whereas respiration was in the order M. trossulus > F. vesiculosus > Z. marina > mixed macrophytes >sands > aphotic sediments. Winter metabolism contributed 22–31% of annual rates. Spatial upscaling revealed that ben-thic habitats drive > 90% of ecosystem metabolism in waters ≤5 m depth, highlighting their central role in carbon andnutrient cycling in shallow waters