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 1978 Bioturbating, filtrating, Habitat structuring

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 293 Barents Sea Species 6 Traits MobilitySpeedStrataBody shapeBody TextureMean weight A theoretically super-vulnerable species

From an given community sample, we can measure the community vulnerability V = community vulnerability v= species vulnerability P = frequency i=1...S species j=1...L locations

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