The Results are Coming in for Island Lake’s BioBlitz!

Two people standing on a bridge looking out over a wetland.

Surveying Invasive Species at Island Lake Conservation Area

This past July, we conducted our first invasive species bioblitz at Island Lake Conservation Area to identify invasive species present in the park. The two-day pilot had staff searching the park’s forests, lake and shoreline looking for invasive forest insects, plants and diseases and invasive aquatic plants, fish and invertebrates.   

Here’s what we discovered.

On Land

During our land surveys, we observed and counted over 2,100 individual invasive plants. The plants cover 435,920 square metres of land area. That’s equivalent to the area of 276 hockey rinks!

Two people on a trail looking at their phones
Staff using their smart phones to record observations.

The top three most observed invasive plants were:

  1. European buckthorn (Rhamnus cathartica) – 772 observations
  2. Invasive honeysuckles (Lonicera spp.) – 415 observations
  3. Glossy buckthorn (Frangula alnus) – 353 observations

European buckthorn was the most pervasive invasive plant at the park. Crews counted an estimated 37,250 individual stems of buckthorn. We also found four invasive plants that are unfortunately available at many garden centers and nurseries in Ontario.

  • Chinese silvergrass (Miscanthus sinensis)
  • Japanese-spurge (Pachysandra terminalis)
  • Yellow iris (Iris pseudacorus)
  • Chinese wisteria (Wisteria sinensis)
Common buckthorn
Common Buckthorn

There is currently no legislation against selling invasive species unless they are listed under the Invasive Species Act. You can help stop the spread of invasive species by choosing native plants for your gardens using our guide to invasive plant alternatives

Japanese knotweed (Reynoutria japonica) is listed as restricted under the Invasive Species Act, which means it cannot be sold or moved. Crews found it in two areas covering a total of 32 square metres. We’ve been prioritizing Japanese knotweed removal at our conservation areas over the past decade. The patches found at Island Lake will be added to the list for future removal work.

Crews also looked for forest pests and were pleased to not find any new invasive insects or signs of dying hemlock trees, as a result of hemlock wooly adelgid (Adelges tsugae). It’s spreading in Ontario but we have not yet observed it in Credit River Watershed. This invasive insect slowly kills eastern hemlock trees by feeding on the tree’s sap. Thankfully it was not observed at Island Lake.

Group of people conducting surveys in a forest.
Staff doing a forest pest transect. 

Invasive forest insects found at Island Lake include:

  • Japanese beetle (Popillia japonica)
  • European praying mantis (Mantis religiosa)
  • Emerald ash borer (Agrilus planipennis)
  • Beech bark disease (Cryptococcus fagisuga and Neonectria faginata)
Two Japanese beetles feeding on a leaf.
Japanese beetle feeding on a leaf.

In the Water

Crews used a number of techniques to look for invasive fish, minnows, mussels and snails in the over 121 hectares of water at Island Lake. This included seine nets at 19 sites, minnow traps at 17 sites and sediment collections at 37 sites. Only one aquatic invasive species was found in abundance: banded mystery snails (Viviparus georgianus).

Hand holding a snail shell in front of an identification card.
Identifying banded mystery snail (Viviparus georgianus).

Crews also looked for plants growing in the lake and along the shoreline. We found three invasive plants:

  • Curly-leaved pondweed (Potamogeton crispus)
  • Eurasian water-milfoil (Myriophyllum spicatum)
  • Phragmites (Phragmites australis australis)
Four people in canoes referring to a paper.
Our experts discussing the identification of narrow-leaved pondweeds.  

The first invasive species bioblitz at Island Lake was a success. Staff sharpened and shared their identification skills and tested new sampling methods. Over the course of two days, priority areas throughout the park were surveyed. As results continue to come in, we will be adding them to our dataset. Using what we learned during this pilot, we will adjust our data collection protocols and apply them at future invasive bioblitzes.

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Comments (8)

    1. Credit Valley Conservation

      Thanks Jean! We only listed the three most abundant plants and then highlighted 4 of the more common nursery species. But both garlic mustard and purple loosestrife were in the top 10 species seen during the blitz (garlic mustard: 1.6 ha and loosestrife 0.7 ha).

  1. Now that the inventory is done, when will the control efforts begin? Will there be an opportunity for volunteering? It would be a great place to showcase best practices to encourage people to deal with the invasive plants on their own property.

    1. Credit Valley Conservation

      Hi Nancy, CVC has been doing some priority invasive management at ILCA since 2011. This includes species such as dog-strangling vine, buckthorn and garlic mustard in priority locations. Coincidentally, last Sat (Sept 10th) we held a buckthorn removal volunteer workday at ILCA, where 16 community volunteers helped weed wrench out buckthorn.

    1. Credit Valley Conservation

      Hi Rob, it depends on size, for smaller stems hand pulling or using a weed wrench are great options. And for larger stems or large patches, it gets more complicated. See OIPC technical bulletin for control details.

  2. Thats great work guys.
    May i ask a question, not being an expert
    I thought Purple Loosestrife was an urgent problem, displacing native Cattails and Reed Grass, reducing wetland areas. I never hear anything these days but I see it everywhere I go
    And I love Cattails !

    1. Credit Valley Conservation

      Hi Antony, purple loosestrife was the first major invasive back in the early 90’s that gained public attention. CVC worked with local volunteers to pull plants and did releases of the biocontrol (neogalerucella beetles) down in the south part of the watershed to help combat the purple loosestrife populations between 1995-1999. Until the mid 2000’s the neogalerucella beetles did a great job at keeping the populations in check. However, by 2015 we started noticing more loosestrife in the upper watershed. So in 2016 we did another release of neogalerucella at two sites (one of which was Island Lake). We are continuing to monitor the population to see if another release will be warranted.

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