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