Publication Date:
2018-09-04
Description:
Marine ecosystems are exposed to increasing
human pressures and climatic change worldwide. It has
therefore become essential to describe ecosystem statuses
with respect to multinational protection schemes,
often necessitating long-term monitoring programmes.
Changes in the food-web structure, which can be monitored
via stable isotope measurements, represent an
important descriptor of the status of marine ecosystems.
We investigated long-term changes (29 years) in isotopic
values (δ13C and δ15N) in four indicative organisms
at different trophic levels in the southern North and
Baltic Seas: bladderwrack (Fucus vesiculosus), blue
mussel (Mytilus ssp.), eelpout (Zoarces viviparus), and
herring gull (Larus argentatus). Time series analyses
using generalised additive models revealed largely consistent
declines in δ13C and δ15N throughout all trophic
levels of the coastal food web at all study sites, indicating
a clear change in these coastal regions from 1988 to
2016. There were no clear long-term patterns in egg
biometrics for herring gulls, except for a consistent
increase in eggshell thickness. The declines in stable
isotope values were in line with the results of previous
long-term studies of single higher-trophic-level species,
which suggested that the noted changes were mainly
caused by altered foraging patterns of the studied species.
The current results demonstrate that declines in
δ13Cand δ15N have occurred throughout the whole food
web, not just in particular species. We discuss the possible
reasons for the decrease in stable isotope values,
including decreasing eutrophication and an increase in
terrestrial carbon sources
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
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isiRev