Ecological Risk Assessment


The Ecological Risk Assessment uses exposure-effect, and also recovery lag, to assess the risk to ecosystems from human activities. The Risk Assessment builds on ODEMM's Linkage Framework and Pressure Assessment. The categories of pressure are assigned numerical scores in the Ecological Risk Assessment to weight and group impact chains in order to prioritise management. Impacts can be grouped across pressures, sectors and/or ecological components, allowing for further exploration of the information at a more aggregated level.

The Pressure Assessment criteria can be directly related to the different aspects of risk (Figure 1), and the categorical assessments of the five criteria in the Pressure Assessment each assigned a numerical score for the risk assessment. Two criteria are used to describe the exposure of the ecological component to a sector-pressure combination, one criterion describes the severity of the interaction, and two criteria describe the time required for the ecosystem components to recover (recovery lag) from an impact (see Figure 1).

Figure 1 Pressure assessment criteria are grouped to assess Impact risk and Recovery Lag under the risk assessment framework

These scores are then combined to give:

  • Impact Risk, which is the combination of scores from the spatial extent, frequency and severity criteria, and where the greater the Impact Risk score, the greater the threat to that component or combination of components, and

  • Recovery Lag, described using a combination of the persistence of the pressure and the generic resilience (recovery time) of the ecological component. This aggregate criterion gives an indication of the time required for potential improvement in ecosystem state to be seen following the management of a specific impact chain, where the greater the recovery lag value, the longer time period required for an ecological component to recover back to its pre-impacted state.



The output is the Total Impact Risk which evaluates the likelihood and consequences of a specific impact chain or combination of impact chains (See Figure 2). The assessment allows the ‘worst’ impact chain or chains to be identified (either in terms of impact risk and/or recovery lag) in isolation or grouped in combinations e.g. by sector or pressure. Impact risk and recovery lag is calculated as the average of all impact chains aggregated by sector, pressure or ecological component. It is then possible to explore how management of particular sectors and/or pressures might reduce risk in the ecosystem (see Further Information below).


Figure 2 An example of Total Impact Risk scores associated with each sector in each European regional sea.


Using the Ecological Risk Assessment

Using the Pressure Assessment, impact risk and recovery lag are scored for all impact chains. Full details of the application are described in Knights et al. (2013) (link available below).

The ODEMM Ecological Risk Assessment (ERA) methodology allows users to identify risks at a broad level, such as that illustrated above for whole sectors. This allows high level prioritisation across and within regional sea ecosystems. To date, the ERA methodology has been applied withb the data generated from the completed Pressure Assessment of Europe's regional seas (see details on Pressure Assessment page). As the approach links directly to the data generated by the ODEMM Pressure Assessment, any update or new application of the Pressure Assessment could then easily be converted into a risk output. Furthermore, it is possible to use the ODEMM ERA for management strategy evaluation (see Resources page on the iMSE tool).

Skills Needed

Running the ERA analysis requires an understanding of ecology and statistics and as the assessment utillises the data from the ODEMM Pressure Assessment it is important that any user understands the methodology and assumptions behind both the ERA and the Pressure Assessment. The contacts given below can be consulted on suitability of the available application and/or generation of a new assessment with the information given below.

Further Information

A description of the methodology plus results from an application in Europe's regional seas can be found in the following report: ODEMM Ecological Risk Assessment Technical Report.pdf

The method is also described in Chapter 5 of ODEMM's final deliverable (Robinson et al. (2014) - ODEMM Report.pdf) and an application is now published in the ICES Journal of Marine Science (Knights et al., 2015; ICES Journal of Marine Science 72(3), 1105–1115. doi:10.1093/icesjms/fsu245)

Developers: Antony Knights, Gerjan Piet, Ruud Jongbloed and Leonie Robinson with contributions from the wider ODEMM team

Tool Contacts: Antony Knights ( or Gerjan Piet (

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