Science > Ecol / Ecos Research > Aquatic Ecotoxicology

Aquatic Ecotoxicology

Study Personnel: David Kreutzweiser (Research Scientist) (705) 541-5648, Scott Capell and Kevin Good (Environmental Technicians)

Under the Aquatic Ecology and Ecotoxicology Study, laboratory and field-based projects are conducted to determine the effects of forest management activities and other disturbances on aquatic organisms and their environment. These include the assessment of forest pesticide effects and the impacts of forest disturbance, such as logging operations. Projects are conducted in collaboration with colleges and universities, other federal and provincial government agencies, and private industries.

A primary objective is to determine how forest management activities and other forest disturbances interact with, and impact on, water resources in forest watersheds. Current research activities fall under the following themes:

Forest Pesticide Effects

With increased emphasis on the development of alternatives to chemical pesticides, several natural and biological materials are being tested for feasibility in forest pest management applications. We conduct experiments to determine individual- to community-level effects of these alternative pesticides on aquatic organisms and ecosystems. Lab experiments are conducted at our Aquatic Ecotoxicology Laboratory located in the Lake Superior State University Aquatic Research Laboratory (http://www.lssu.edu/arl/). Flow-through toxicity test units and re-circulating microcosms are used to determine direct and system-level toxic effects of alternative pesticides on microbial communities, macroinvertebrates and larval fish.

For testing under more natural conditions, stream and pond mesocosm studies are performed at the Icewater Creek Research Area north of Sault Ste. Marie. Under these controlled field conditions, pesticide effects on aquatic insects, zooplankton communities, microbial processes and algal biomass are investigated. Projects under this theme currently or recently include the environmental assessments of an ecdysone-agonist insecticide, tebufenozide (Mimic), and a natural, botanical insecticide from neem seed kernel extracts, azadirachtin (Azatin, Neemix).

Fate and Effects of a Genetically Engineered Insect Virus in Aquatic Systems

One alternative pest management strategy being developed is the use of genetically engineered insect viruses. Because these viruses are highly specific to the target insects, they can be used as a means of transferring a genetic insert into a target insect with little risk of cross-transfer or adverse effects in non-target organisms. The genetic inserts can increase the insecticidal activity of the virus in the target insects, thus providing a biological insecticide for pest management applications. However, if genetically engineered insect viruses are to be considered as alternative insecticides for pest management programs, the environmental safety of these viruses must be demonstrated.

Aquatic microcosm protocols have been developed and implemented to test the fate and effects of these genetically engineered insect viruses. The microcosms are designed to closely simulate natural water bodies and contain natural surface water and organic bottom substrates. Replicate microcosms are inoculated with wild type (natural) insect virus or recombinant virus. Response parameters are measured in the virus-contaminated microcosms and compared to replicate control microcosms. Measurements include water quality, microbial decomposition activity, microbial respiration, and microbial community structure (as determined by differential carbon source utilization in Biolog microplates). The distribution and fate of the virus in water and organic bottom substrates are being tracked by DNA extraction and polymerase chain reaction (PCR) techniques. Outdoor aquatic mesocosms (in-ground polyethylene tanks) are also used for testing under more natural conditions. Protocols for sampling, extracting and detection of natural and recombinant viral DNA in these quasi-natural aquatic systems are under development.

Effects of Alternatives to Forest Clear-cutting on Habitat and Biota of Headwater Streams

Partial Harvesting. Environmentally focussed forestry practices are being developed and implemented across Canada. As alternative forest management techniques and strategies are developed and tested, it is essential that environmental studies are conducted at the same time to ensure that the alternative practices are in fact providing significant environmental protection. Large-scale field projects have been established to investigate the effects of harvesting disturbance on processes and structure of the forest ecosystems. One of these projects is located in the tolerant hardwood forests of the Lake Superior shoreline at the Turkey Lakes Experimental Watershed. This is a multi-agency, multi-disciplinary project investigating many silvicultural and environmental aspects of partial-cut harvesting. Our group is focussing on headwater streams and their associated biota. Responses in streams of watersheds harvested at varying degrees of disturbance are being compared to nearby undisturbed streams.

Primary emphasis of the study is on determining effects of forest harvesting on the biodiversity of aquatic invertebrates. Associated habitat parameters are also being measured. These include bottom substrate characteristics, debris dam frequency, organic matter deposition and characteristics, woody debris distribution, canopy composition, sedimentation on stream beds, and organic matter inputs. Other study groups are monitoring further stream quality parameters to which biotic responses can be linked. These include continuous discharge measurements, water temperatures, water chemistry, and groundwater and nutrient inputs.

Fire. In May 1999, a boreal mixedwood research site at Black Sturgeon Lake north of Nipigon, Ontario was completely burned by wildfire. A baseline data set on the habitat and biota of low-order watersheds had been established in preparation for a further forest harvesting impacts study. The wildfire provided impetus and opportunity to characterize the effects of extensive fire across contiguous watersheds on stream ecology. This study is ongoing and examining effects of wildfire on stream habitat characteristics and aquatic invertebrate communities.

Riparian Harvesting. A third multi-agency, inter-disciplinary research project has been established with the support of the Ontario Living Legacy Trust near White River, Ontario to examine the ecological consequences of partial harvesting in riparian areas of boreal streams. The objective is to determine if partial harvesting at up to 50% removal in riparian zones of boreal streams can be conducted without adverse ecological effects. The study also provides ecological information on the structure and function of riparian areas of low-order boreal mixedwood watersheds. Response variables include fisheries habitat, aquatic invertebrates, songbird communities, shoreline salamander populations, vegetation responses, ground disturbance, harvesting productivity, and flying insect populations. Emphasis is on the ecological linkages among these components, their contributions to riparian ecological function, and their responses to harvesting disturbance.

Ecological Responses in Headwater Streams to Varying Carbon Fluxes Across Land/Water Interfaces

Most climate change models predict that this part of North America will experience warmer, wetter winters and hotter, dryer summers over the next several decades. This is likely to result in changes to the quantity and quality of water draining forest watersheds. Increased winter and spring runoffs, followed by lower-than-normal summer and fall stream flows are predicted under a climate change scenario. Associated with these changes in stream flow, are likely to be alterations in the production and transport of nutrients and sediments across land/water interfaces. Our research efforts are directed at determining the ecological consequences of these changes in nutrient flux, and at examining the ecosystem processes underpinning these changes.
Current activities are focussed on dissolved organic carbon (DOC) production, movement and ecological effects in headwater streams of forest catchments. In particular, we are examining the influence of climate change (drier summer conditions through watershed manipulation) on the quantity and quality (bioavailability) of DOC transported to receiving waters, and the influence of differential DOC sources on microbial community function in headwater streams. Microbial endpoints are being measured because this is the trophic level that is likely to be most sensitive to changes in DOC, and because microbial communities play a vital role in almost all energy transfer processes and subsequent biotic community structuring in aquatic systems. The experimental approach includes the use of outdoor stream mesocosms in which microbial responses to differential DOC are determined. Field studies in low-order forest watersheds are being conducted in which the production and export of DOC, and microbial responses in receiving waters will be investigated across an ecophysiological gradient reflecting different climatic conditions. These ecophysiological conditions are being exaggerated by further watershed manipulations.