ABSTRACT
Professional judgements will always form an intrinsic part of environmental assessment. No matter what method is applied for identifying and evaluating impacts, it is not possible to conduct an environmental assessment without relying on expert opinions. For this reason alone, team selection is crucial to the success of any EIA. Although expert opinion is not a method, it can be considered a tool for assessing complex project impacts. The ability of standard checklists and other generic tools is limited to the accurate identifi cation of a wide range of indirect impacts that may occur because of a project activity. Consider, for example, the range of potential impacts on an aquatic ecosystem due to mine water discharge. These include, but are not limited to (USEPA 2000): (1) death of fi sh, invertebrates, plants, domestic animals, or wildlife; (2) abnormalities in life forms, such as tumours, lesions, parasites, disease; (3) altered community structure, such as the absence, reduction, or dominance of a particular taxon (including increased algal blooms, loss of mussels, increase of tolerant species, etc); (4) loss of species or shifts in abundance; (5) response of indicators designed to monitor or detect biological, community, or ecological condition, such as the Index of Biotic Integrity (IBI) or the Invertebrate Community Index (ICI); (6) changes in the reproductive cycle, population structure, or genetic similarity; (7) alteration of ecosystem function, such as nutrient cycles, respiration, and photosynthetic rates; and (8) alteration of the geographic extent and pattern of different ecosystems, for example, shrinking wetlands, change in the mosaic of open water, wet meadows, sandbars, and riparian shrubs and trees. It is clear that even the most experienced aquatic biologist would be challenged to identify all potential impacts prior to further site-specifi c studies.
