Have you been enjoying the fall colour nature walks this month?

If so, chances are you’ve likely passed through a marsh, swamp or bog – which are all important forms of wetlands!

Did you know that wetlands help absorb the impact of flooding, filter sediments/toxic substances, and provide food and essential habitats for many species of fish, waterfowl, and mammals? They are very important ecosystems.

Wetlands were once evenly distributed throughout Canada, but are now increasingly scarce due to many factors – including the introduction of invasive species.

Trent University PhD candidate in the Environmental and Life Science Program, Verena Sesin (pictured below), has dedicated her research to exploring ways to help wetland managers control invasive species in a sustainable way.

Gardening for Science – Potting Plants for Verena’s Next Experiment (photo by R. Hamp)

Invasive plants, like the Phragmites australis (European Common Reed), are taking over wetland habitats, affecting the overall health of wetland ecosystems.

To eliminate and control invasive species, wetland managers often use a herbicide called GLYPHOSATE, which is highly toxic to many plants and can help kill off unwanted invasive plants from wetland areas.

Ideally, glyphosate application would remove all invasive plants and leave native plants untouched for a chance to recolonize the wetland… however, this is not the case!

Glyphosate is non-selective, meaning it will kill many plants in its path. Spraying this herbicide in biodiverse wetlands can harm both native and invasive species.

How can we use this herbicide more effectively to remove invasive species, but keep native ones healthy?

Verena is addressing this question with her research to attempt to discover a balanced approach to glyphosate-based invasive plant control, that effectively removes invasive plants while minimizing risks to native plants.

Verena conducted various experiments including:

  1. Planting 56 micro-wetlands in the Trent research gardens, packed with both native and invasive species to model a real wetland;
  2. Harvesting plant leaves from invasive plants that had been previously sprayed with glyphosate to see if the plant litter leached glysophate;
  3. Using a mist bottle to spray plants with a range of glyphosate solutions and monitoring plant growth and survival over time; and
  4. Comparing potential side effects on native plant species from different glyphosate application methods, including spraying and hand-wicking.

A perfect summer day for Verena – checking on her micro-wetlands – a total of 56 of those blue tubs placed into the Trent research garden (photo by V. Sesin)

Verena’s research findings show that:

  1. Plant species vary in their glyphosate sensitivity. Some plants are even 5 times more sensitive than others!
  2. Hand-wicking, rather than spraying, the plants to apply the herbicide can help reduce the risk of native plants nearby being negatively affected.
  3. Sprayed plants can accumulate glyphosate in their leaves and stems which can later leach into the water – potentially affecting other plants.
  4. Removing sprayed plants that may continue to leach glyphosate in the wetland could be considered to limit potential effects on other wetland biota.

Verena hopes her research findings will increase our understanding of potential risks of glyphosate applications in wetlands, and ultimately will be translated into sustainable wetland management practices by wetland managers.

Stopping the spread of invasive plants to protect wetlands is important – but it should be done in a careful and sustainable way that limits the harmful effects that herbicides can have on nearby native plant species.

Sightseeing in Hong Kong with Trent peers Erika Crowley (left) and Amanda Stubbs (right) after a great day at the IIES Graduate Students Forum Asia (photo by E. Crowley)

Thank you Verena for your important work that helps protect our wetlands!

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

Trent University is a hotspot for environmental science, with so many dedicated faculty and staff that are supporting me to do interdisciplinary work and to think outside the box. I also love Trent’s open community and many opportunities to get involved in campus life – such as seminars, student interest groups and varsity sports. I am happy to have met passionate and inspiring people through both my graduate program and other groups I have joined, including the Trent Graduate Students’ Association and the Trent Varsity Cross Country team. My most memorable experiences were trips to workshops and graduate student forums in Hong Kong and Edinburgh organized by the International Institute for Environmental Studies (IIES) at Trent, where I could share my research, meet like-minded people, and make meaningful connections for the future.