The Seasonal Contribution of Different Celtic Sea Shelf Sediments to Benthic Carbon Cycling

Continental shelf sediments are responsible for sequestering significant amounts of organic carbon annually, and this usually occurs in cohesive sediments. It is still unclear how much variation there is in organic carbon sequestration between different sediment types (cohesive, permeable), and the relative spatial and temporal variability of these measurements. Here we present initial findings on community respiration rates (diffusive and total oxygen uptake rates) from whole core incubations experiments run on three cruises in the Celtic Sea. Sampling covered four different benthic sites (mud, sand, muddy sand and sandy mud), representing a gradient between cohesive and permeable sediments. Sediment cores were collected pre-, during- and post-phytoplankton bloom, to encompass the different organic matter inputs reaching the benthos over an annual cycle. There are clear differences in oxygen uptake rates between sediment type, and a trend according to season, which links directly to organic matter input. This demonstrates the relative contribution of the micro and meiofauna to community respiration, and the organic carbon turnover rates for different shelf sea sediments in the Celtic Sea.