EXECUTIVE SUMMARY
Under the auspices of the Aquatic Effects Technology Evaluation (AETE) Program, a literature review was undertaken to assess eight population level, benthic macroinvertebrate fitness parameters as potential biomonitors for the Canadian mining industry. The parameters were reviewed primarily from the perspectives of ecological significance, technical ease/constraints of execution, and business considerations such as labour requirements and general costs of application. The macroinvertebrate fitness parameters reviewed were:
- density (no. individuals/species/area)
- size (head-width, total body length)
- condition (weight/head-width)
- fecundity (no. eggs/female)
- adult emergence (no. individuals, timing of emergence)
- distributional changes (micro-distributional changes on or within substrate)
- morphological deformities (irregularities in structure of menta and antennae)
- fluctuating asymmetry (FA) (irregularities in bilateral symmetry)
These eight parameters were chosen because the first six have a history of use over the last 25 years in assessing natural and anthropogenically induced stress (i.e., impairment to Darwinian fitness) within both lotic and lentic ecosystems. Parameters 7 and 8 have been utilized to measure impacts within aquatic systems primarily since 1990 onward. Of the eight parameters listed, variability in benthic macroinvertebrate density, at both the population and community levels, has been a tool used by the mining industry to assess potential impacts within aquatic systems. Parameters 2-8 are discussed within an “exploratory context” for the mining industry, relative to the utility they may offer to assess potential impacts within aquatic ecosystems.
The linkage of benthic macroinvertebrate species to one another and other components within food webs/ecosystems is illustrated based on research documenting the complex structure and dynamic nature of food webs. These illustrations demonstrate that factors impacting one component of the food web can potentially have a cascading impact upon others. These linkages indicate that by biomonitoring the fitness of benthic macroinvertebrates, extrapolations may be made regarding the health of the food web and the overall potential impacts of mining activities.
Several advantages associated with the use of macroinvertebrates (e.g., general ubiquity, relatively high abundance, short life cycles, general sedentary nature, well defined taxonomy, relative ease of collection) to evaluate the potential impact of stress within aquatic ecosystems are outlined. The utility and advantages of population level rather than community level measures are discussed. Literature suggests that an examination of four species of intermediate density per site is the optimal choice to assess impacts, between control and reference sites, in a practical, meaningful and cost-effective manner.
While each of the eight fitness parameters discussed may be useful biomonitors from a scientific or ecological perspective, not all would be appropriate for use in evaluating environmental impacts from a technical and cost perspective. Based on an extensive literature review and discussions with Beak Environmental Consultants Ltd. and EBA Engineering Consultants Ltd., technical aspects of application and associate costs suggest that density, size, condition, morphological deformities and fluctuating asymmetry may be most useful to assess the effects of mining within aquatic ecosystems. Although analyses of fecundity, adult emergence and distributional changes offer meaningful ecological insight, consultants suggest these parameters may be prohibitively time consuming and costly to apply.
The literature reviewed in this study should provide a foundation upon which pilot experiments may be conducted to ultimately determine whether, and which, population level macroinvertebrate fitness parameters are practical, meaningful and cost-effective as biomonitoring tools for the mining industry. As the study illustrates, the application of these eight parameters to mining is at an elementary stage (with the exception of density), thus pilot experiments to explore the utility of these parameters appear to be a “logical next step”.
