Identifying impact with ERSEM
Published: 14 February 2017
MERP models will be used to predict the ecosystem response to a number of scenarios, covering changes in nutrient loading, fishing pressure and climate change. To ensure we capture the cascade of changes from hydrodynamics, nutrients and plankton to fish, sea birds and marine mammals, 3D simulations of ERSEM in the UK shelf seas are used to quantify the changes in habitat (temperature, salinity, currents) and productivity associated with each scenario. These then drive the higher trophic levels models. The 3D ERSEM simulations are performed as part of the Shelf Sea Biogeochemistry (SSB) programme.
In SSB, ERSEM is used to quantitatively describe the cycles of carbon and major nutrients (nitrogen, phosphorus and silicon) and to assess how much they are impacted by anthropogenic disturbances, such as eutrophication and bottom trawling, or by global changes like climate change and ocean acidification. To fully disentangle the impact of those drivers, a series of scenarios is being run on the NERC supercomputing facility ARCHER to simulate the dynamics of the North Western European Shelf at 7 km resolution (“AMM7”), under different intensity of activities (e.g. different nutrient discharge from rivers, different trawling intensity).
ERSEM outputs will also be used to study the dynamics of the four major planktonic and benthic groups included in the model, and how these vary with time and with ecosystem properties. Simulated community composition will be validated using data collected during MERP.
In phase II (2017- 2019) of MERP's Module 6, further 3D simulations will be used to test a range of new ERSEM features developed for MERP (e.g. diversity in size and feeding of zooplankton and benthic fauna) in a realistic setting. This will allow studying in greater detail what drives the spatial and temporal dynamics of community diversity as well as assessing the impact of this on the biogeochemical cycling of carbon and nutrients. To achieve this goal, we will increase model resolution from 7 km to 1.5 km, allowing important mixing processes, due to eddies and internal tides, to be resolved. The figure shows the effect of the change in resolution in the currents' speed in the Celtic Sea domain (“CS15”). We will use this domain to study the impact of the emerging small-scale physical features (e.g. coastal front, offshore eddies) on biodiversity.