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Symphony: a tool for ecosystem-based marine spatial planning


Symphony is a model-based tool developed to support the implementation of ecosystem based maritime spatial planning. It is developed for Sweden but can be transferred to other countries. The model depicts through maps and other graphical representations (including sensitivity matrix), how ecosystem components respond to human pressures. The Symphony method provides valuable analyses for MSP in any context and informs planners of the baseline conditions and the potential effect of various planning options on the cumulative impacts in different areas.


Application in MSP:
Type of Issue:
Type of practice:
Stage of MSP cycle:
Cross-border / trans-national aspect:
Coherence with other processes:
Key words:

Questions this practice may help answer

  • How can cumulative impacts be assessed during different stages of the MSP process?

  • Which tool or methods are available for the assessment of environmental and cumulative impacts on ecosystems?

  • How are sensitivity matrices developed for ecosystems components?

Implementation Context

Marine spatial plans are the basis for governments on how to use marine space. The EU MSP Directive indicates that the planning shall be based on an ecosystem approach. Additionally, co-existence of uses or reduction of conflicts shall be promoted. In the context of the required Environmental Impact Assessment (EIA) during a planning process, information about cumulative impacts is core to make decisions. Symphony offers planners an analytical tool to estimate the cumulative environmental impact during the planning process. It allows early identification of areas of concern to consider mitigating planning options. Symphony provides information about cumulative impacts on the national level. In parallel there exist tools and models for the global (Halpern 2008), the continental (Micheli 2013), the regional (HARMONY, BSI) and the local (BAN 2010) level. 

The model was developed and applied as part of the Swedish MSP process in 2015 as well as in 2018 for the development of the draft of the Swedish maritime spatial plan based on an ecosystem approach. In parallel to the development of Symphony for the Swedish MSP, a similar approach was applied by Helcom in their holistic assessment of the Baltic sea (HOLAS). The basic method behind Symphony has been used for cumulative impact assessment in other parts of the world.

Aspects / Objectives

  • Assess the cumulative impacts of human activities and other pressures on various ecosystem components.

  • Identify areas of concern in the early stages of the planning process to inform development of scenarios for planning and implementation

  • Promote coexistence among marine uses and activities while protecting the ecosystem


The basic methodology for Symphony was based on scientific work by Halpern et al. (2008). Symphony nonetheless took this a step further through integration with ecosystem based MSP. Symphony is applied by calculating the cumulative impacts from the sum the average of all pressures’ effect on all considered ecosystems values (ecosystem components).  The Swedish territorial waters and EEZ is divided into cells of 250 by 250 m and the environmental impact is calculated for each cell. The final impact values are illustrated by colours to define the level of impact. The following 5 steps were applied as a methodology:

  1. Ecosystem Components: Development of maps of ecosystem components based on already existing data. It included data from 32 different ecosystem components
  2. Pressures: Development of pressure maps showing spatial extent of human activities governed by the MSP and aligned with their respective user areas in the plans. It included data from 41 different pressures. These are then aligned with the respective user areas in the plans in order to and develop and compare different plan alternatives based on impacts.
  3. Sensitivity Matrix: A sensitivity matrix was developed to model how sensitive each ecosystem component is to each pressure. This information was gathered through expert opinion.
  4. Baseline Results: This is made up of a calculation of each geographic unit to represent the current situation, using the formula:

Cumulative impact (P) is calculated as the sum or mean of the product of all pressures’ (B) effect on all ecosystem components (E), given the particular sensitivity (K) of every ecosystem component to every pressure.

5. The results are interpreted and recalculated for different plan options in order to compare alternatives and find plausible solutions.

Main Outputs / Results

The output when using the tool is a GIS based map with the predicted cumulative impacts for the coastal and marine areas of the Baltic Sea. The figures below show examples of various outputs.


Fig 1: Example showing the pressure Toxic metals in sediments, one of the 41 included pressure maps.

Fig 2: The map compares environmental impact in the different areas defined in the consultation version of the state-owned marine plan with environmental impact throughout the entire North Sea area. The Percentage comparison is based on average per area.

Fig 3: Geographical distribution of cumulative environmental impact in the North Sea. The color scheme range from lowest environmental impact (0%) to maximum environmental impact in the North Sea (100%) which is found in a small area outside Gothenburg, not included in the impact heat map shown here.

Please note that regarding figure 3, impacts in coastal waters are generally higher compared to offshore areas but coastal waters are not included in the national MSP. These coastal areas are included in Symphony but not covered by the heat map shown here.

Fig 4: Example of changes in cumulative impact when drafted plans are compared to the current state. Green shades indicate lower impact and red shades indicate higher impact, as a result of the MSP.


The tool is transferable in other countries provided that the data of the specific region or sea basin are fed into the database.

Contact Person

Jonas Pålsson
Senior Analyst, PhD 
Havs- och vattenmyndigheten / Swedish Agency for Marine and Water Management 
+46 (0)10-698 62 54 
+46 (0)76-538 61 87 (jonas[dot]palsson[at]havochvatten[dot]se)

Linus Hammar
Senior Analyst
Havs- och vattenmyndigheten / Swedish Agency for Marine and Water Management 
+46 (0)10-698 61 15 (linus[dot]hammar[at]havochvatten[dot]se)

Responsible Entity

Swedish Agency for Marine and Water Management