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 <25% to >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.