What can ecosystem models tell us about the risk of eutrophication in the North Sea?

S Saux Picart,S Wakelin,M Butenschön,J Holt,L De Mora,J I Allen,Y Artioli

doi:10.1007/s10584-014-1071-x

S Saux Picart, S Wakelin + Show 5 more

Open Access

https://doi.org/10.1007/s10584-014-1071-x

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Abstract

Eutrophication is a process resulting from an increase in anthropogenic nutrient inputs from rivers and other sources, the consequences of which can include enhanced algal biomass, changes in plankton community composition and oxygen depletion near the seabed. Within the context of the Marine Strategy Framework Directive, indicators (and associated threshold) have been identified to assess the eutrophication status of an ecosystem. Large databases of observations (in situ) are required to properly assess the eutrophication status. Marine hydrodynamic/ecosystem models provide continuous fields of a wide range of ecosystem characteristics. Using such models in this context could help to overcome the lack of in situ data, and provide a powerful tool for ecosystem-based management and policy makers. Here we demonstrate a methodology that uses a combination of model outputs and in situ data to assess the risk of eutrophication in the coastal domain of the North Sea. The risk of eutrophication is computed for the past and present time as well as for different future scenarios. This allows us to assess both the current risk and its sensitivity to anthropogenic pressure and climate change. Model sensitivity studies suggest that the coastal waters of the North Sea may be more sensitive to anthropogenic rivers loads than climate change in the near future (to 2040).

Highlights

Shelf seas are the most highly productive regions of the world ocean providing a diverse range of goods and services
Eutrophication is a process resulting from an increase in anthropogenic nutrient inputs from rivers and other sources; the consequences of which can include enhanced algal biomass, changes in plankton community composition and oxygen depletion near the seabed
Amongst the variety of indicators commonly used to evaluate the eutrophication status, we chose a sub-sample for which a large number of measurements are available, and we define thresholds drawing on the Common Procedure (OSPAR 2005) as a basis to develop and demonstrate our methodology

Summary

Introduction

Shelf seas are the most highly productive regions of the world ocean providing a diverse range of goods (e.g., food, renewable energy) and services (e.g., carbon, nutrient cycling, biodiversity and transport). Eutrophication is a process resulting from an increase in anthropogenic nutrient inputs from rivers and other sources; the consequences of which can include enhanced algal biomass, changes in plankton community composition and oxygen depletion near the seabed. All of these effects have been observed in the southern North Sea (e.g., Lenhart et al 2010; Weston et al 2008). Downscaled climate forced simulations of marine ecosystems indicate that increased stratification in the NE Atlantic leads to a reduced oceanic nutrient supply into the North Sea, potentially leading to a significant reduction in primary production by 2100 (Holt et al 2012)

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