Evaluating impacts of bottom trawling and hypoxia on benthic communities at the local, habitat, and regional scale using a modelling approach

Bottom trawling disturbance and hypoxia are affecting marine benthic habitats worldwide. We present 22 an approach to predict their effects on benthic communities, and use the approach to estimate the state, 23 the biomass relative to carrying capacity, of the Baltic Sea at the local, habitat and regional scale. 24 Responses to both pressures are expected to depend on the longevity of fauna, which is predicted from 25 benthic data from 1558 locations. We find that communities in low-salinity regions mostly consist of 26 short-lived species, which are, in our model, more resilient than those of the saline areas. The model 27 predicts that in 14% of the Baltic Sea region benthic biomass is reduced by at least 50%, whereas an 28 additional 8% of the region has reductions of 10-50%. The effects of hypoxia occur over larger spatial 29 scales and lead to a low state of especially deep habitats. The approach is based on a simple 30 characterization of the benthic community, which comes with high uncertainty, but allows for the 31 identification of benthic habitats that are at greatest risk and prioritization of management actions at the 32 regional scale. This information supports the development of sustainable approaches to manage impact 33 of human activities on benthic ecosystems.