measuring the vulnerability of a community to a given pressure: benthos species and bottom trawl in...
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Measuring the vulnerability of a community to a given pressure:
Benthos species and bottom trawl in the Barents Sea.
Jørgensen, LL, Certain G, Thangstad T, Planque B
Spatial workshop outputs: Annual meeting Paris 3-7 Dec 2012
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How environmental disturbance affects a community of species
Divers benthic community delivering ecosystem goods and services
Benthic end member community with few number of opportunistic species
Mixture where S, A and B increase
Disturbance
Modified after Pearson & Rosenberg 1978Bio
turb
atin
g,
filtr
atin
g,
Ha
bita
t st
ruct
urin
g
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Classical, experimental approach to measure disturbance effect on biodiversity:
Benthic community
Environmental noise Directed disturbance (”Pressure a, b or c”)
Need to identify “fingerprints” from a given pressure
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Trawling impact 2
93 B
aren
ts S
ea S
pec
ies
6 TraitsMobility Speed Strata Body shape Body Texture Mean weight
A theoretically super-vulnerable species
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From an given community sample, we can measure the
community vulnerability
V = community vulnerabilityv= species vulnerabilityP = frequencyi=1...S speciesj=1...L locations
S
i i
ijj v
pV
1 1
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Application to Benthic communities in the Barents Sea (1)
Robust communities in trawled area
All types of communities in untrawled area
Low Vulnerability High
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Conclusions
•This general method estimate the community vulnerability toward a given pressure (given that species vulnerability to a given pressure can be assessed)
1. Define manageable units (polygons) based on biota, climate, bottomtop,sed, drivers.
2. Identify LTDS of manageable pressures and natural drivers
3. Use 1 and 2 to follow fixed polygons over time?
4. Look into recovery rates by the use of “protected areas” controlled experiments with vulnerable keyspecies
Way forward