A dynamical systems approach to modeling growth, spread, and control of invasive watermilfoil.

Current project members: Diana White and Jonathan Martin (Clarkson University, Mathematics), Michael Twiss (Clarkson University, Biology), and Kyle Monette (Clarkson Mathematics Undergraduate). Work is completed in collaboration with the Norwood Lake Association (NLA).

Past project members: Isabel Dengos (MSc in Mathematics, Clarkson)

*Project funded by the NYS DEC through their invasive species irradiation program.

In September 2016, I started modeling biological invasions in my own backyard (literally!). In particular, I'm working to develop a model to study the spread and biological control of invasive watermilfoil, one of the most invasive aquatic plants in the US. The test site I'm looking at is Norwood Lake (where I live), a small reservoir located along the Raquette River in Upstate New York.

Invasive watermilfoil project on Norwood Lake, Upstate NY

pull5.jpg
pull5.jpg

The end result (photo credit: Michael Twiss). The milfoil collected from a hand harvest can be used as fertilizer for local farmer's fields. It's important to make sure that wet milfoil doesn't make it's way back into a water body, since small fragments can remain viable for extended periods of time, growing new roots and creating new plants/problems if introduced back into the water.

press to zoom
20180608_142155.jpg
20180608_142155.jpg

Variable-leaf watermilfoil early June in Norwood Lake 2017 (Photo credit: Diana White). VLM begins growing in early/late spring, and depends on a variety of water conditions. As the season progresses (ending in early Fall), the plants out-compete most other native plants, to form a thick/dense canopy on the water surface.

press to zoom
pull2.jpg
pull2.jpg

Members of Clarkson and the Norwood community take advantage of a 12-foot drawdown to pull an 800 m^2 area of watermilfoil (photo credit: Michael Twiss)

press to zoom

ODE modeling: Modeling watermilfoil growth in a dense patch

milfoil2.png
milfoil2.png

Total biomass over time (left: shallow water, right: deep water).

press to zoom
milfoil5.png
milfoil5.png

Model sensitivity. Left: end of season (EOS) biomass vs lake depth, (middle) EOS biomass vs lake transparency, (right) EOS biomass vs temperature.

press to zoom

PDE modeling: Modeling the spread and control of invasive watermilfoil

milfoil4_edited.jpg
milfoil4_edited.jpg

Top: control using mats (mat applied for 30 days at T = 100 days). Note the overall decrease in end of season biomass. Bottom: No control.

press to zoom
milfoil.png
milfoil.png

press to zoom