Evelyn Robertson is a recent graduate from the Trent University Bachelor of Science Honours in Environmental and Resource Science.

She just completed her undergraduate research thesis studying invasive species in the Trent River.

Invasive species are animals or plants that have entered an ecosystem from another region of the world – and they don’t belong in their new found place.  They can harm the natural resources in an ecosystem and threaten human use of the affected areas.

watersoldierShip ballast water, accidental release, and human-caused entries (such as moving wood from one area to another) are all reasons invasive species can find their way into a new area – and most often, they aren’t welcome. 

Unfortunately, invasive species are capable of causing extinctions of native plants and animals and significant biodiversity loss.

Invasive species compete with native organisms for limited resources, causing a major threat to their livelihood. In addition, habitats are often significantly altered, resulting in huge economic impacts and disrupted ecosystems.

Evelyn’s research focused on the water soldier,  an invasive perennial aquatic plant native to Europe and Northwest Asia.  In 2008, this invasive plant was found near the Hamlet of Trent River, Ontario – the only known wild population in North America.


Because this plant is commonly used as a decorative plant in water gardens – it is suspected that this is likely the source of its introduction in the Trent River.

The presence of water soldier in water bodies can cause significant damage to ecosystems, such as:

  • Shading out native plants;
  • Altering the chemistry of the surrounding water;
  • Reducing recreational activities like swimming and boating due to dense mats of vegetation; and
  • Harming swimmers and people that handle the plant through its serrated leaves.

Evelyn’s research sought out to discover the beneficial and/or harmful effects of one plant on another plant from the release of biochemical (known as allelochemicals) from plant parts through both natural and agricultural systems.

She studied this allelopathic relationship between the COONTAIL (a native plant) with the WATER SOLDIER (an invasive plant).

In aquariums, Evelyn grew both plants for a 21 day period and weighed them every day to find trends in their changing biomass. She then placed them in containers of water that had been previously exposed to the other species to see the change in photosynthesis rates over time.

Evelyn discovered there was a significant decrease in both the growth rate and photosynthesis of water soldier (invasive) when in the presence of coontail (native)

This means that water soldier turions (waterlike buds or seedlings) may not be able to compete with their native counterpart, the coontail and that they would not be able to grow and survive where coontail grows.

Evelyn’s research showed that strengthening lake and river resistance to invasive plants can be facilitated by ensuring native species are growing healthily.

She mentioned we must work to regulate environmental stresses and disturbances caused by human impact. If we can protect the native plants in our lakes, our water bodies will be in better condition to fight invasive plants. 

One of the consequences of climate change is the increase in cases of invasive species entering unwelcoming territories due to environmental stresses in their native areas – so we must ensure our water bodies are healthy enough to withstand their introduction.

Thank you Evelyn for this important research! 


Here is what Evelyn has to say about her experience at Trent University:

“Even though Trent is smaller compared to other universities, it has done an amazing job providing a wide range of opportunities to all students, being able to complete this research happened to be one of these opportunities for me. My supervisor, Dr. Eric Sager, was always ready and willing to support me throughout the different stages of the research. Professors at Trent always make time for undergraduate students who are interested in pursuing any research, and without their dedication, Trent wouldn’t be the amazing school I just graduated from!”