Final Report of the Working Group on Integrative Physical-biological and Ecosystem Modelling (WGIPEM)

The Working Group on Integrative Physical-Biological and Ecosystem Modelling (WGIPEM) met in Copenhagen, Denmark, on 16–20 April 2018. 29 participants from 11 countries discussed recent advances in biological-physical modelling approaches and how to make best used of complex models. Modelling approaches considered are various and range from hydrodynamic-biogeochemical models to individual-based models (IBM) as well as spatially explicit foodweb models and so called end-to-end models.This year, a particular attention was put on addressing the possible uses of models by a wider community (including stakeholders). Through a joint session with the Working Group on Multispecies Assessment Methods (WGSAM) about model skill assessment, the group concluded on the necessary honesty regarding model skills and the value to transparently report strengths and weaknesses. Differentiating between model skills in hindcast and forecast was found important, and the usefulness of sensitivity anal-yses was reasserted for gaining insights in model and system behaviour and better prioritizing parameterization efforts. WGSAM and WGIPEM agreed to work together in future in order to produce practical guidelines on model skill assessment and har-monize methods within ICES. A joint session was also organized with the Working Group on Integrated Assessments of the North Sea (WGINOSE) and the Working Group on Ecosystem Assessment of Western European Shelf Seas (WGEAWESS) to increase interactions between these groups as we move towards the operationalization of the Ecosystem Based Management (EBM) in the North East Atlantic area. Intergrated Ecosystem Assessments (IEA) groups appear to have more contacts with stakeholders than WGIPEM, which is sometimes associated with semi-quantitative modelling ap-proaches. Comparison of approaches and/or using complex models to better quantify the links between compartments in IEA approaches are two possible pathways for fu-ture collaboration. Furthermore, integrated models were proven useful to explore un-certainty due to sampling design of sea surveys, and such results could be transferred to other ICES groups.As part of WGIPEM mission to identify gaps of knowledge, a discussion with WGINOSE and the Benthos Ecology Working Group (BEWG) was organized to ad-vance on the representation of benthos within integrated models. Additionally to fruit-ful exchanges regarding available data on spatial distribution of benthic species, habi-tat mapping, state and trends of species, the importance of traits rather than taxonomic description was reasserted when aiming at modelling the functioning of ecosystems. Moreover, it was recognized that not only benthos descriptions, but also sediment fluxes are a challenge to model realistically.