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
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
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
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
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
Application to Benthic communities in the Barents Sea (1)
Robust communities in trawled area
All types of communities in untrawled area
Low Vulnerability High
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