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Marine Strategy Framework Directive

BLUE2 Integrated Source-to-Sea Modelling

Integrated numerical modelling frameworks can be useful for several purposes related to the MSFD, such as to determine baseline conditions from the past, estimate the future impact of pressures and the suitability of measures, complement scarce datasets and help prioritize sampling activities.

  • Topic / Tool | Last updated: 29 Oct 2026
Marine Strategy
Blue2

The Blue2 is a comprehensive suite of modelling tools, developed by the JRC's D2 Ocean and Water Unit. This framework encompasses a variety of models designed to simulate and evaluate European Union marine ecosystems comprehensively across diverse management and policy scenarios.  It covers the Mediterranean Sea, Baltic Sea, North Sea, Bay of Biscay and Iberian coast and Black Sea.  It includes the following set of models:

blue2 diagram
Land-use models

The land-use model is CAPRI, a global agro-economic model used to assess impacts of agricultural, trade and environmental policies on the agricultural sector. This module depicts the spatial and temporal aspects of agricultural practices e.g., the evolution of nutrients from mineral fertilizer, manure and crop fixation impacting land and freshwater-marine environments.

Hydrological models

These models simulate the freshwater conditions of EU rivers and lakes regarding their quality (nutrient concentration) and quantity (water flow). More specifically, the freshwater nutrient levels are computed by the Geospatial Regression Equation for European Nutrient losses (GREEN) hydrological model. GREEN includes a geospatial data model for Europe, where data are linked to the hydrological structure of the river network to model nitrogen and phosphorus flow in the river basin according to different pathways (Grizzetti et al., (2017) and Grizzetti et al., (2025)). Europe is divided into c.a. 1 million catchments of 7 km2 average size. In complement, GREEN incorporates the freshwater flux from the LISFLOOD model. The freshwater flux and nutrient loads at the land / sea interface are used as inputs by the hydrodynamic and biogeochemical ocean model.

Hydrodynamic and biogeochemical models

The hydrodynamic component of Blue2MF is the General Estuarine Transport Model (GETM) that simulates marine water dynamics (current, temperature, salinity), permitting a realistic description of each EU seas in a 3D manner. The biogeochemical module, tailor fitted for the characteristics of each basin, simulates nutrient transport and fate within the planktonic food web.

Lagrangian model

LTRANS-ZLev model is used to simulate the dispersion, accumulation and beaching of floating inert particles, such as plastic debris, within marine environments.

High Trophic Levels (HTL) Model

Also known as ecosystem  models, these assess the dynamics of marine organisms, ranging from phytoplankton to top predators, including fisheries. The HTL is simulated using Ecopath with Ecosim (EwE) which captures the structure and the dynamics of the marine food webs. A specific configuration is set up for each EU region (the Mediterranean Sea and the Black Sea). The HTL component uses the physical (i.e., temperature, salinity) and biogeochemical (i.e., phytoplankton biomass) fields generated by the coupled hydrodynamic-biogeochemical model.

BLUE2

Each of the modelled EU marine regions has a tailored setup and different spatial resolutions to account for specific characteristics of the marine ecosystems. The external forcing and conditions (e.g., the atmospheric conditions) are identical to all models to ensure consistency in scenarios testing.

By integrating key physical, chemical, and biological components across diverse management and policy scenarios, Blue2 provides essential support for informed policy decisions. Its practical applications have included:

  • evaluating the effects of water scarcity on marine ecosystems and its implications for the blue economy
  • examining the impact of macrolitter on megafauna
  • investigating the consequences of eutrophication on EU marine ecosystems

 These outcomes are pivotal in underpinning essential EU policies and strategies aligned with the "source to sea" approach. This approach emphasises the interconnectedness of terrestrial, freshwater, and marine environments, promoting holistic management and conservation efforts.

The Blue2  Integrated Source-to-Sea Modelling supports key EU environmental policies, notably including:

  • Water Resilience Strategy
  • Ocean Pact 
  • Marine Strategy Framework Directive
  • Biodiversity Strategy
  • Water Framework Directive
  • Zero Pollution Action Plan

 Additionally, the framework may contribute to Maritime Spatial Planning Directive and the Common Fisheries Policy. 

Explore further

Coastal Blue Carbon

In the BLUE2 framework, Coastal Blue Carbon (CBC) specifically describes the carbon stored in coastal vegetated ecosystems (e.g., seagrass meadows) and associated sediments.

The overlooked impacts of freshwater scarcity on oceans as evidenced by the Mediterranean Sea

Water stress is an urgent issue in many regions worldwide, particularly in southern European countries. This study reveals the consequences of decreased freshwater flow on marine ecosystems in the Mediterranean…

Assessing the potential for seaweed cultivation in EU seas through an integrated modelling approach

The potential of large-scale seaweed cultivation to contribute to achieving ambitious EU-wide objectives, such as food security, energy independence, carbon neutrality and ecosystems restoration, is widely recognized…

Water/marine Zero Pollution Outlook

Forward looking analyses are needed in order to anticipate which policy/management options can deliver the very ambitious objectives of the Zero Pollution (ZP) action plan…

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