Working Group on Integrative, Physical-biological and Ecosystem Modelling (WGIPEM)

<p dir="ltr">The Working Group on Integrative, Physical-biological and Ecosystem Modelling (WGIPEM) aims to facilitate end-to-end ecosystem modelling by bringing together marine ecosystem modellers working on ocean physics, lower and higher trophic levels, encouraging knowledge exchange and networking between them. To this end we focus on model development, model coupling and model skill assessment. Process-based ecosystem models have a large potential for use in marine management, from assessing the spatial and temporal impact of marine protected areas and offshore renewable energy projects to helping define the baseline for eutrophication assessments. Here, models can simulate different management options (e.g. relocation of fishing effort around protected sites, impact of the Baltic Sea Action Plan nutrient ceilings), quantifying their marine impact on an ecosystem level. These models are specifically adept at so called Before-After-Control-Impacts studies in that context. Conclusions drawn from such work (increase in fish biomass and biodiversity inside closed areas does not offset the loss of these outside the areas, the proposed nutrient ceilings will not lead to desired Chlorophyll-a concentrations in the Western Baltic) are extremely relevant to efficient, cost-effective marine management.</p><p dir="ltr">The actual use of ensemble ecosystem modelling in setting the official thresholds for eutrophication indicators in the 4th application of the OSPAR Common Procedure hopefully marks a turning point for use of modelling in management. Despite the clear advantages uptake of modelling in marine governance remains low, as policy-makers prefer observational evidence to simulated evidence. WGIPEM is challenging this situation by means of opinion pieces, stating that observational data should be validated using models to determine their spatial and temporal representativeness. The relevance of this work is clear: members have shown that cruise direction strongly influences cruise results, that indicator assessments can change drastically depending on the temporal and spatial distribution of sample points used, and have demonstrated its feasibility by quantifying how representative a single observational station is within its wider coastal environment.</p><p dir="ltr">Recently many modelling studies have focused on the impact of offshore renewable energy extraction and climate change impacts. Here members found that wind farms can have far-field impacts on marine ecosystems, but also that tidal currents can mitigate some of the hydrodynamic effects. Climatic changes can disrupt fish larval development by an increasing mismatch (spatial, temporal) between early life stages and their food supply, affecting recruitment success for commercial species. This type of work is facilitated by the new Online Model Library of Larval Fish, allowing for easier knowledge access on larval stage parameterizations. The library also highlights the large knowledge gaps in this area.</p><p dir="ltr">Exciting new developments in ecosystem modelling include incorporation of evolutionary dynamics (including descriptions of individuals’ genetic structure) and the thermal time concept (more directly linking physiological performance with environmental forcing). These developments may be crucial to simulate marine ecosystem change among a multitude of stressors. But to gauge the impact of the changing environment on people’s livelihoods the models should be used together with socio-economic scenarios, as demonstrated by a coupled model study in Patagonia. This way social equity can also be brought into the realm of marine decision-making.</p>