A Procedure for Ecological Tiered Assessment of Risks (PETAR)
Doctoral thesis, 2002

Institutions in developed countries have proposed several Ecological Risk Assessment (ERA) procedures, and the majority of study cases have been carried out there. The use of (often expensive) existing ERA procedures in developing countries is questionable given their limited resources and scarce background information of relevance for risk assessments. There is an obvious need to adapt existing ERA procedures to account for data gaps and constrains on the acquisition of new data without compromising the scientific value of the assessment. This thesis presents a "Procedure for Ecological Tiered Assessment of Risks" (PETAR), which consists of a three-tiered evaluation of risks, successive tiers requiring more detailed investigations. The tiered approach assures that resources available for site-specific investigations are directed toward answering well formulated questions raised during the early stages of the assessment. The first tier, the preliminary assessment, is a qualitative evaluation of existing information on stressors, sources of stressors and expected ecological effects. The second tier is the regional risk assessment, a semi-quantitative evaluation of ecological risks posed by environmental problems over large geographical areas, which results in a ranking of sources and stressors having the greatest potential for ecological impact and subareas inside the study area more likely to be impacted. The final tier is a local risk assessment, a quantitative assessment of ecological risks posed by environmental problems over small geographical areas that incorporates methodologies for establishing causality between exposure to multiple stressors and effects on endpoints of ecological relevance. The applicability of the PETAR procedure was verified by a case study conducted in a reserve of the Atlantic rain forest in Brazil. Results of the evaluation of risks at the regional scale can be used by the reserve administration to establishing conservation priorities. The evaluation of risks at the local scale effectively assessed the causes and consequences of environmental degradation in a small geographic area.

local scale

regional scale

developing country


rain forest

multiple stressors


ecological risk assessment



Rosana Moraes

Department of Environmental Systems Analysis

Subject Categories

Other Environmental Engineering



Report - Department of Environmental Systems Analysis, Chalmers University of Technology: 2002:12

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 1929

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