Publication Date:
2017-02-09
Description:
The degradation of ecosystems is often associated
with losses of large organisms and the concomitant
losses of the ecological functions they mediate.
Conversely, the resilience of ecosystems to stress is
strongly influenced by faunal communities and
their impacts on processes. Denitrification in
coastal sediments is a process that may provide
ecosystem resilience to eutrophication by removing
excess bioavailable nitrogen. Here, we conducted a
large-scale field experiment to test the effect of
macrofaunal community composition on denitrification
in response to two levels of nutrient
enrichment at 28 sites across a biologically
heterogeneous sandflat. After 7 weeks of enrichment,
we measured denitrification enzyme activity
(DEA) along with benthic macrofaunal community
composition and environmental variables. We
normalised treatment site specific DEA values by
those in ambient sediments (DEACN) to reveal the
underlying response across the heterogeneous
landscape. Nutrient enrichment caused reductions
in DEACN as well as functional changes in the
community; these were both more pronounced
under the highest level of nutrient loading (on
average DEACN was reduced by 34%). The degree
of suppression of DEACN following moderate
nitrogen loading was mitigated by a key bioturbating
species, but following high nitrogen loading
(which reduced the key species density) the
abundance and diversity of other nutrient processing
species were the most important factors
alleviating negative effects. This study provides a
prime example of the context-dependent role of
biodiversity in maintaining ecosystem functioning,
underlining that different elements of biodiversity
can become important as stress levels increase. Our
results emphasise that management and conservation
strategies require a real-world understanding
of the community attributes that facilitate nutrient
processing and maintain resilience in coastal
ecosystems.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
,
info:eu-repo/semantics/article
Format:
application/pdf
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