My research is primarily field-based and focused on improving our ability to assess ecosystem health using fish populations as an integrator of environmental condition.
I developed an effects-based ecosystem health assessment approach that uses data on growth and reproductive rates, survival, and indicators of condition to generate and test site-specific hypotheses that identify stressors responsible for changes in fish populations.
I try to understand the responses of wild fishes to natural and anthropogenic stressors including inputs from pulp mills, oil refineries, agriculture, and municipalities, assess the suitability of laboratory or artificial studies for predicting field effects.
My current interest lie in developing a new paradigm for ecosystem health assessment, developing methods for watershed-level cumulative effects assessment and testing hypotheses about the role that variation in fish reproductive life histories plays in species differences in detecting impacts, recovering from impacts and how to predict impacts.
Long term and short term objectives
My long term objectives are to broaden the understanding of fish reproductive strategies, use this understanding to generate new models, sampling designs and strategies for achieving environmental protection goals, and to disseminate these finding by providing a stimulating training environment for both students and environmental professionals that is interdisciplinary in nature and international in focus. The short term objectives of are to test a series of hypotheses about
- the relationship between a species’ reproductive strategy and its sensitivity to population-level impacts of contaminants,
- using natural variability in habitat to develop predictive capabilities of reproductive development and growth, and
- how reproductive strategies affect the potential for recovery from long term contaminant exposures.
Understanding fish population responses to stressors requires an interdisciplinary approach at various spatial and temporal scales and this research capitalizes on related studies in my lab on focused on the relationship of molecular signals of exposure to whole organism consequences, and the ecological relevance of indicators.
Most significant research contributions (2004 to present)
Most of my research relates to improving the sensitivity of monitoring programs to detect environmental impacts of stressors on fish, designing novel approaches to optimize these programs in terms of sensitivity and relevance, and developing approaches for detecting and understanding cumulative effects. My research formed the basis for the development of Federal Environmental Effects Monitoring (EEM) programs for pulp and paper mills (1992), metal mines (2001), and municipal waste dischargers (gazetted Feb 2010).
Impact of fish reproductive life history on sensitivity to pollution: Prior to the development of EEM requirements, the focus had been on understanding how fish communities or measures of abundance are affected by industrial effluents. As a result of my earlier studies, regulated Canadian monitoring programs have shifted to monitoring individual fish species. Species available for monitoring vary widely across Canada, as do their reproductive strategies and timing of spawning, and there was little known about which to choose and when to sample to understand environmental impacts.
It was not known how that variability affects species sensitivity to environmental impacts. We compared seasonal changes in reproductive profiles and patterns in 8 species with differing reproductive strategies; these data were used to define optimal sampling windows for monitoring programs to detect impacts on reproduction which have been incorporated into the new guidance documents for EEM programs.
A review of >500 recent monitoring programs in Canada has shown that when small-bodied fish species were collected outside of the optimal sampling period (73% of the time), they showed a reduced responses or no response as compared with collections conducted during peak reproductive development. These observations are providing the focus for new hypotheses about the ways in which variation in reproductive life history affects sensitivity of fish species to environmental contamination
Development of a framework for cumulative effects assessment: Although there is a regulated requirement in Canada to conduct cumulative effects assessment for new developments, there are no accepted methods for understanding the responses of fish populations to multiple environmental stressors.
Over the last 20 years I have developed an effects-based approach to this kind of assessment - this framework has grown out of a series of projects on multiple stressors that I led to develop a method for determining the causes of impacts. I have applied this effects-based approach in the Saint John River, and have been invited by governments to apply this approach in numerous rivers across Canada and internationally.
Investigation of non-point source impacts from agriculture on fish populations: Impacts of non-point sources like agriculture on wild fish have not been widely studied. A number of my recent students have examined its impacts on fish growth, reproduction, survival and distributions. Our research has shown that, in spite of the variety of stressors in agricultural areas, the best predictors of risk to fish populations are maximum summer temperature and intensity of summer (July, August) rainfall.
My recent Uruguayan research has shown that sediments and water from agricultural areas are associated with significant endocrine impacts and fish reproductive risk , which has resulted in significant international invitations to collaborate on novel approaches for monitoring agricultural impacts in Uruguay and Sri Lanka.
Impacts of pulp and paper effluents on fish populations: Beginning in 1989, my laboratory was the first to find that effluent from some pulp mills was capable of delaying sexual maturity and reducing gonadal size in fish. We were also the first to examine the impacts of pulp mill process type, the benefits of modernization, and installation of waste treatment on wild fishes, and I have completed several recent reviews and developed guidance for monitoring of this industry in Canada and Chile.
The Canadian pulp mill industry is in trouble and many facilities are closed. My recent research is looking for signs of recovery of fish populations after mill closure, modifying laboratory studies for understanding the mechanisms underlying the timing of recovery, defining critical effect sizes for study designs, and proposing alternate approaches for field studies, as well as short term indicators of impacts, the development and refinement of non-lethal sampling methodologies, and the potential for new modern mills in South America to cause reproductive impacts.
My expertise has been recognized with numerous invitations to speak, teach courses or review developments in 9 countries; I was on the Organizing Committee of the 8th Pulp Mill Conference and co-hosted the 9th Internat Conf (Fredericton, 09). I am on the EEM National Science team (since 1999), am regularly consulted by industry and government for advice on study designs, and have received invitation internationally from government and industry to Industry meetings in Chile, to give short courses to industry in Brazil, by the World bank to review a development in Uruguay (declined), and to review potential threats of development.
Impacts of sewage effluents on fish populations: Whereas most recent work has focused on the endocrine impacts of chemicals in sewage effluents, my lab’s research has been on assessing whole organism effects to look at the consequences of exposure. We are developing methods to separate the effects of sewage from other effluents in the field, and using these wastewaters as model effluents for refining laboratory bioassays to detect endocrine effects.
We recently demonstrated that invertebrate populations show similar population-level responses as fish to sewage and pulp mill effluents, and that responses to sewage can be much stronger than to other effluents. I have also co-developed monitoring programs for sewage outfalls and results of these studies have directly contributed to a new regulation requiring EEM for municipal discharges (published in Feb 2010), and with the Water Environment Research Foundation (US).