Is watercress helping or hurting P.E.I. streams? A UPEI student aims to find out

CBC

17-06-2025

If you're near a freshwater stream or river in Prince Edward Island this summer, you might spot UPEI biology student Julie Goodwin at work.
Goodwin is spending the summer tracking watercress, an aquatic perennial herb that grows in slow-moving bodies of water and is also edible. Her goal is to learn where watercress is growing and how it's affecting Island streams.
She said not much is known about the plant's history on the Island, so her work is helping create a snapshot for future research. It could also support better decisions about whether the plant should be controlled.
"We have baseline data from when it was introduced, but that was quite a while ago," she told CBC's Island Morning.
"Since then, there has been no distribution tracking. We don't know now if it has gotten more abundant, if it has moved downstream, if it's moved to other streams. And just because it's not reported somewhere, that doesn't mean it's not there."
So far, she said, a lot of what's known about watercress distribution on P.E.I. has come from citizen science through platforms like iNaturalist. The app allows users to share photos and locations of plants and animals, helping researchers gather data for scientific and conservation purposes.
"In the world… plant collection and plant identification is a serious issue. There is a lack thereof," she said.
Benefits and drawbacks
Goodwin said that after speaking with different watershed groups, she learned the impact of watercress varies depending on the environment.
"Some watershed groups have mentioned that it grows so abundantly that it over-widens their streams and causes flooding, which damages aquatic habitats, and it out-competes native plants," she said.
"However, other groups have just noticed it kind of sitting along the banks, catching sediment, even being nursery habitat... I myself have seen frog eggs laid on watercress early in the season."
That variation highlights why more data is needed to better understand the plant's role in Island ecosystems, Goodwin said.
"There's lots of relationships in the ecosystems in which the watercress resides, and understanding those relationships is really what this project is about," she said.
"We want to understand why it's here, what's interacting with it, what kind of changes it might be having in the ecosystems. And from there, we can then go on to collect more data and more data over the years and be able to track it. And, really, that will move toward proper management and conservation."
How Islanders can help
Goodwin is hoping Islanders can help her gather data this summer. She's asking people to snap photos of any watercress they come across and upload them to iNaturalist.
She said those who want to contribute directly can also send photos to her email along with the GPS co-ordinates, which are easily accessible from most smartphones.
That information will be added to her personal monitoring system and help identify at-risk areas that might be more likely to accumulate watercress.
"Eventually, once we have enough data, and once we do a bit of a pilot study this summer, hopefully we can develop a practical monitoring system that watershed groups can use to track it every year. And it's not just a summer project," she said.