Biogeochemical responses of intertidal sediments to simulated warming and epi-faunal loss: a mescosm experiment.

Ocean warming and the disproportionate loss of larger (often predatory) fauna are major threats to seabed (benthic) ecosystem functioning. In a mescosm study we tested how faunal species loss affects microbial carbon sequestration and retention in intertidal sediments, under both ambient and predicted warming conditions (ambient + 2 deg C), whilst manipulating the presence/absence of the shore crab Carcinus maenas. We used stable isotope pulse-chase techniques to trace the fixation and retention of a fixed dose of 13C-labelled sodium bicarbonate within sediment organic matter and microbial biomass. These datasets include the environmental conditions (Temperature, Salinity, Oxygen Concentrations and pH) within the mesocosms and the biogeochemical responses of the surfical (00-0.5 cm) sediment layer. This includes changes in chlorophyll a concentrations and chlorophyll a patchiness over time, differences in concentrations and 13C-enrichment of the sediment Total Organic Carbon (TOC) and microbial Polar Lipid Fatty Acid (PLFA) between treatments, and profiles of the relative abundance of the individual PLFAs and 13C-labelled PLFAs (in molar %).