Related to WP 2.2

Version 20 Nov. 09

Tool title and potential use

Vulnerability index for surface water ecosystems

Novelty and background

Ecosystem vulnerability is an underdeveloped concept in ecotoxicological risk assessment.
Ecotoxicological risk assessment is not only required for general objectives, such as the continental-scale regulation of chemical substances. The scale of environmental management is usually smaller and requires assessment on relatively small geographic units (hydrographic basins, local administrative units, etc.), where site-specific approaches are required for protecting specific ecosystems. The responses of different ecosystems to a particular stressor may be very different. Therefore, information on the characteristics of potentially endangered ecosystems is essential in site-specific risk assessment.
Ecological vulnerability must be assessed at different hierarchical levels (population, community, ecosystem, landscape). The problem is not easy, particularly if one considers that the responses of different populations are generally different as a function of different stressors. Moreover, ecosystem vulnerability considers the response at the community level. The characteristics of a community are not merely the sum of the characteristics of individual populations; structure and function of the community are also regulated by emergent properties that are not easily described and predicted from lower hierarchical levels.
A numeric “Vulnerability index” has been developed, in order to evaluate the potential response of aquatic ecosystem features to multiple stressors.

Description of tool and current state

The “Vulnerability index” is defined by the following algorithm:

where:
Vx = Vulnerability of ecosystem to stressor X
Sex = Score attributed to the influence of the stressor X on the Sensitivity of the community
Sux = Score attributed to the influence of the stressor X on the Susceptibility to exposure
Rx = Score attributed to the influence of the stressor X to Recovery capability
HAx = Score attributed to the influence of the stressor X on the Habitat Alteration
Sex, Sux, Rx and HAx are defined by a simple scoring system (from 0 to 3), developed to estimate the influence that a potential stressor can produce on a given component of the vulnerability
The index has been successfully applied to two Italian rivers in different quality conditions.
More applications and calibration would be useful.

References

1.  Ippolito A, Sala S, Faber J H , Vighi M (2009). Ecological vulnerability analysis: a river basin case study. Sci Total Environ.
2.  De Lange H J, Sala S , Vighi M, Faber J H (in press)
Ecological vulnerability in risk assessment - a review and perspectives , Sci Total Environ

Responsible scientists:

Marco Vighi, University of Milano Bicocca,

Alessio Ippolito, University of Milano Bicocca,