Sub-PI on July 13, 2023
Patrick Siwula, WI DNR Southeast Region AIS Coordinator and Amanda Schmitz, WI DNR Waukesha AIS Coordinator, completed the 1st of 2, sub-Point Intercept aquatic plant surveys on July 13, 2023.
The sampling grid for the sub-PI was centered on waypoint 397. This location is where the 1st finding of SSW was found during the August 2022 Full-PI survey. The sub-PI grid has 64 sampling points. The map of the grid includes the legend and scale.
SSW was found in 10 of the 64 locations that were sampled at a depth of 3 to 7 feet. On their way back to the Hart Drive launch, 3 additional SSW locations were observed that were outside the sub-PI grid.
WDNR Comments & Recommendation:
Overall, the SSW is primarily concentrated in the area of full PI point 397. Fortunately, in that area, the SSW was co-occurring with many native aquatic plant species (along with the Eurasian Watermilfoil), which is what they were hoping to find.
The additional SSW patches, that were outside of the sub-PI grid, on the way back to the launch were a little bit larger than what they saw by full PI point 397 (~ 3’x3’ – 5’x5’), but were also completely surrounded by native plant growth or Eurasian watermilfoil. This again is what they were hoping to find, that any SSW patches would be intermixed with or surrounded by strong aquatic plant communities that will provide competition with the SSW.
Overall, the littoral zone (where there is enough light to support plant growth) was almost entirely vegetated, meaning that there is not currently a lot of ‘open real estate’ for SSW to move into.
Patrick Siwula discussed these results with Heidi Bunk as well as the Statewide Limnologist (Michelle Nault) and AIS Program Lead (Amy Kretlow):
The SSW is not currently dominating where found, topping out, causing navigational issues, etc.
The native plant community was observed to be quite robust around the SSW, including dense chara and coontail in many locations.
In light of these findings, the WDNR recommended not pursuing a management intervention, such as hand pulling, for the SSW at this time.
Additional Resources:
You can find out more about Starry Stonewort on the WDNR Starry Stonewort website page.
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