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.
Ireland ->
Maynooth University ->
Type = Article
Ireland ->
Maynooth University ->
Academic Unit = Faculty of Science and Engineering: Research Institutes: Hamilton Institute
Ireland ->
Maynooth University ->
Status = Published
Nicholas V.C. Polunin,
Andrew Parnell,
Nicola D. Walker,
Aileen C. Mill,
Simon Jennings,
Jessica I. Duffill Telsnig