Publication Date:
2019-07-17
Description:
Ecosystems are under pressure from multiple human disturbances whose impact may
vary depending on environmental context. We experimentally evaluated variation in the
separate and combined effects of the loss of a key functional group (canopy algae) and
physical disturbance on rocky shore ecosystems at nine locations across Europe.
Multivariate community structure was initially affected (during the first three to six
months) at six locations but after 18 months, effects were apparent at only three. Loss
of canopy caused increases in cover of non-canopy algae in the three locations in
southern Europe and decreases in some northern locations. Measures of ecosystem
functioning (community respiration, gross primary productivity, net primary productivity)
were affected by loss of canopy at five of the six locations for which data were
available. Short-term effects on community respiration were widespread, but effects
were rare after 18 months. Functional changes corresponded with changes in
community structure and/or species richness at most locations and times sampled, but
no single aspect of biodiversity was an effective predictor of longer-term functional
changes. Most ecosystems studied were able to compensate in functional terms for
impacts caused by indiscriminate physical disturbance. The only consistent effect of
disturbance was to increase cover of non-canopy species. Loss of a canopy algae
temporarily reduced community resistance to disturbance at only two locations and at
two locations actually increased resistance. Resistance to disturbance-induced
changes in gross primary productivity was reduced by loss of canopy algae at four
locations. Location-specific variation in the effects of the same stressors argues for
flexible frameworks for the management of marine environments. These results also
highlight the need to analyse how species loss and other stressors combine and
interact in different environmental contexts.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
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