Ecotoxicology

Ecotoxicology is the study of the movements of toxic materials through the environment and their effects on living organisms and ecosystems.  Materials that have acute or chronic effects on development or the functioning of organisms can reduce their evolutionary fitness and alter the outcome of ecological interactions.  These effects can thus potentially alter the structure of populations and communities, and ultimately the functioning of ecosystems.

 

The level of toxicity of materials varies widely as do their effects among species.  Natural materials can have toxic effects, but effects of anthropogenic chemicals is particularly interesting and of concern because living organisms and natural ecosystems do not have co-evolutionary experience with these contaminants.

 

 

 

 

 

 

 

 

Deformed tail of a tadpole exposed to road de-icing salt

Photo: D. Sanzo

 

 

 

 

 

 

 

 

Some species may be particularly vulnerable to pollution because of their biological characteristics and habitat requirements.  Amphibians are considered to be sensitive to contaminants because of their permeable skin and dependence on water.  Many amphibians require aquatic or moist habitats for reproduction, development, foraging or hibernation.  Many species also require adjacent terrestrial habitat for foraging, hibernation, or dispersal.  Most North American amphibian species follow a bi-phasic life cycle of aquatic larvae and terrestrial adults.  Because of their biological characteristics, habitat requirements, and sensitivity to pollution, amphibians are considered to be excellent indicators of ecosystem health.       

 

We are studying the effects of two widely used substances on amphibians.  Nitrogen based fertilizers are heavily used globally, are highly soluble in water, and often enter wetlands via agricultural runoff at critical times during amphibian life cycles.  Another widely used environmental contaminant in northern countries is road-deicing salt.  Chloride concentrations are rising in many areas because salts in road runoff enter adjacent wetlands and accumulate.  We are studying effects of nitrate fertilizers and sodium chloride on growth, development, behaviour, and survivorship of larval amphibians.  Our approach is primarily lab-based where we can obtain precise control in acute and chronic experiments using larvae of aquatic amphibians.

 

Tank set up for tadpole chronic toxicity experiment     Photo: D. Sanzo

 

We also collaborate with other researchers in studying the toxicological effects of organochlorine contaminants on amphibians and reptiles using field sampling.  Although these chemicals are not highly soluble in water, they are lipophilic, persistant, and can bioaccumulate in food webs.  Concentrations and effects of organochlorine contaminants such as DDT, DDE and PCBs can persist for centuries after application ceases.  Funding of our ecotoxicological research has provided by NSERC and Parks Canada.    

 

Jar set up for acute toxicity experiment                     Photo: D. Sanzo

 

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