Data from: Estimating contributions of pelagic and benthic pathways to consumer production in coupled marine food webs

1. Pelagic and benthic systems usually interact, but their dynamics and production rates differ. Such differences influence the distribution, reproductive cycles, growth rates, stability and productivity of the consumers they support. Consumer preferences for, and dependence on, pelagic or benthic production are governed by the availability of these sources of production and consumer life history, distribution, habitat, behavioural ecology, ontogenetic stage and morphology. 2. Diet studies may demonstrate the extent to which consumers feed on prey in pelagic or benthic environments. But they do not discriminate benthic production directly supported by phytoplankton from benthic production recycled through detrital pathways. The former will track the dynamics of phytoplankton production more closely than the latter. 3. We develop and apply a new analytical method that uses carbon (C) and sulfur (S) natural abundance stable isotope data to assess the relative contribution of pelagic and benthic pathways to fish consumer production. 4. For 13 species of fish that dominate community biomass in the northern North Sea (estimated >90% of total biomass), relative modal use of pelagic pathways ranged from 85%. Use of both C and S isotopes as opposed to just C reduced uncertainty in relative modal use estimates. Temporal comparisons of relative modal use of pelagic and benthic pathways revealed similar ranking of species dependency over four years, but annual variation in relative modal use within species was typically 10-40%. 5. For the total fish consumer biomass in the study region, the C and S method linked approximately 70% and 30% of biomass to pelagic and benthic pathways respectively. As well as providing a new method to define consumers' links to pelagic and benthic pathways our results demonstrate that a substantial proportion of fish biomass, and by inference production, in the northern North Sea is supported by production that has passed through transformations on the seabed.Sulphur stable isotope data for North Atlantic (North Sea) fishesSulphur stable isotope data were collected for the study of food webs and benthic-pelagic coupling in the North Sea. They comprise natural abundance stable isotope measurements of δ34S for 415 individuals from 15 species of fish sampled in 2006. Measurements of δ13C and δ15N for the same individuals were previously published by Jennings and Cogan (2015). A numeric code is included with the present data to allow the δ34S measurements to be matched to the δ13C and δ15N measurements by individual. Trophic level estimates for the same individuals, based on δ15N measurements, are provided in Supplementary Material supporting Jennings and van der Molen (2015). Please read the README file for information.SIA_S_North_Sea_fishes_20171129.cs