Publication Date:
2017-02-23
Description:
A sound knowledge on trophic interactions is essential to understand ecosystems and their
resilience to anthropogenic perturbations. Stable isotope analysis (carbon and nitrogen) and
literature information on taxon-specific prey spectra were combined to explore the food web
structure of two major benthic assemblages in the German Bight (southern North Sea): the
Amphiura filiformis-association of silty sands, and the Tellina fabula-association of fine
sands. Carbon isotopic signatures of suspended particulate and sediment organic matter were
consistent with ranges reported for temperate marine phytoplankton, suggesting that both food
webs are mainly fueled by pelagic primary production. More negative δ13C values at the
Amphiura filiformis-station furthermore indicated a small contribution of continental organic
matter at this station, which is located off the Weser and Elbe estuaries. Primary consumer
feeding guild composition varied between assemblages, reflecting differences in physical
properties of sediments and food availability: deposit- and interface feeders were the most
important primary consumer guilds in the Amphiura filiformis-association, whereas filter- and
interface feeders played a major role in the Tellina fabula-association. Both communities had
four trophic levels, with fishes and predatory polychaetes occupying the highest trophic
positions. While primary consumer guilds occupied the same trophic level in the Amphiura
filiformis-association, deposit feeders of the Tellina fabula-association had a trophic level
intermediate of other primary and higher order consumer guilds, likely due to differences in
species composition and selective feeding. Both food webs were characterized by their high
directed connectance, trophic generalism of consumers, and a large proportion of cannibalistic
taxa. These features are characteristic of marine food webs in general, but also reflect a
selection for opportunistic taxa in the southern North Sea, a region characterized by high
levels of environmental and anthropogenic disturbances.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Thesis
,
notRev
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