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Aquatic Invasive Species

Introduction to Aquatic Invasive Species 

Invasive species are one of the major threats to biodiversity and ecosystem health globally. Their introduction causes negative environmental, economic and social impacts. The following list highlights some of these negative impacts: 

    1. Disruption of local food chain 
    2. Outcompeting for resources 
    3. Habitat destruction 
    4. Disruptions in the nutrient cycles 
    5. Impacts on water quality 
    6. Introduction of disease 
    7. Impacts on forest and soil structure 
    8. Threats and impacts on endangered and/or culturally significant species 

Invasive species are able to rapidly establish themselves into new environments outside of their natural ranges. There are several reasons why invasive species are able to establish themselves quickly: 

    1. Lack of natural predators 
    2. Quick reproductive rates 
    3. Native species lack the defence mechanisms needed to combat them

The Situation in Georgian Bay 

Since Georgian Bay is subject to both aquatic and terrestrial invasive species. This page will focus on the aquatic invasive species, more specifically fish and invertebrates, and information on the terrestrial (and wetland fringe) invasive species can be found on our Terrestrial Invasive Species page

One of the major concerns in the Georgian Bay ecosystem is the impact of invasive species on species at risk and their habitats, as Georgian Bay is home to approximately 50 species at risk [Species at Risk page]. The presence and impact of invasive species are subject to change with climate change which makes this a dynamic and ever-evolving issue. 

The Round Goby 

The Round Goby is a bottom feeding fish that was introduced into the Great Lakes System in ~1990 through ballast water and was able to spread rapidly. The main threats they pose on the Georgian Bay and the Great Lake Systems are their negative impacts on the local aquatic species populations. They feed on smaller aquatic organisms and fish eggs, including several species at risk and sport fishing species. This has led to changes in the natural fish populations and food chain, and impacts on the local sport fishing industry. 

There have been possible links to botulism in birds who consume the Round Gobies. It is believed that zebra and quagga mussels that contain toxins, Botulism Type E, are consumed by the round goby and move up through the food chain to other predatory fish and birds that feed on them. For more information on this, check out our post on this topic. Round Goby are now prolific – there may be more than 100 billion of them in the Great Lakes. Consequently they are providing a food source for most larger predatory fish. 

For more information check out these information pages 

    1. Ontario’s Invading Species Awareness Program: Round Goby 
    2. Georgian Bay Forever: Invasive Round Gobies
    3. Invasive Species Centre: Round Goby   
    4. State of the Bay: Round Goby: Fishing for facts: how is the Round Goby so successful?

Zebra and Quagga Mussels 

Zebra Mussels have a long history in Georgian Bay as they were introduced into the Great Lakes System through the discharge of ballast water in ~1986. The Zebra mussels were able to quickly establish themselves within the Great Lake Systems and Georgian Bay due to their rapid reproductive rates. They are able to attach themselves to most hard substrates (rocks, pipes, boats, etc) which leads to the disruption of fish habitat, public nuisance, property damage and the blocking of water intakes. Zebra mussels filter out plankton which disrupts the natural food chain and leads to changes in nutrients available in the ecosystem.

Similar to the Zebra Mussels, the Quagga mussel was introduced through the discharge of ballast water in ~1989. Quagga mussels are similar to the Zebra mussels and impact the ecosystem in similar ways except that the Quagga mussels have been shown to inhabit a larger range of depth than the Zebra mussels and can attach themselves to both soft and hard substrates. The Quagga mussels will outcompete the Zebra mussels when they are present in the same environment. 

For more information check out these information pages 

    1. Nature Conservancy of Canada: Zebra Mussels 
    2. Invasive Species Centre: Zebra and Quagga Mussels 
    3. State of the Bay: Zebra and Quagga Mussels 
    4. Ontario’s Invading Species Awareness Program: Zebra and Quagga Mussels  
    5. Animal Diversity Web: Dreissena bugensis 
    6. Animal Diversity Web: Dreissena polymorpha
    7. Quagga and Zebra Mussel Fact Sheet

Invasive Asian Carp Species (the new potential invasive species)

There are four main species of Asian Carp: Bighead, Silver, Grass and Black, that are a concern for the Great Lakes and Georgian Bay ecosystems. In general the Asian Carp threaten the local ecosystems through their disruption of the food chain and habitat but each individual species poses a unique threat to the ecosystem.

The Bighead Carp and Silver Carp pose similar threats. They have no natural predators, out-compete native aquatic species for resources (but not with each other), continuously feed as they lack a “true stomach” , and are able to cross breed with each other. The Silver Carp also disrupt recreational activities as they jump out of the water when triggered by vibrations, such as a boat motor. The Black Carp also lacks natural predators which leads to the disruption of the local food chain and fish habitat. They would consume native freshwater mussels whose populations are under stress within Ontario. 

There is no clear evidence that Bighead, Silver and Black Carp have reached the Great Lakes yet, but Grass Carp have. They also lack natural predators and disrupt the ecosystem as they consume ~40% of their body weight in aquatic vegetation daily. This is a major threat to the coastal wetlands of Georgian Bay, as the coastal wetlands provide multiple ecosystem services. In addition to the threat to the coastal wetlands, the Grass Carp only digests ~ 50% of the vegetation and expels the rest which leads to increased nutrients in the system. Excess nutrients can lead to unfavourable conditions for certain aquatic species and development of harmful algal blooms. 

Check out our Asian Carp information page for further information and the current status on what’s being done to combat this issue.

For more information see: 

    1. Asian Carp Canada
    2. Invading Species Awareness Program: Asian Carp  
    3. Georgian Bay Forever: 4 Species of Asian Carp + the Common Carp 
    4. Invasive Species Center: Asian Carp Canada Update 

More Aquatic Invasive Species 

The Great Lake System varies over a large geographic area and therefore the distribution of invasive species varies depending on ecological conditions. In addition to invasive species currently present within the Great Lake System there are several species that have the potential to enter into the system and establish themselves. The following list provides additional information on the other most relevant invasive species. 

Currently in The Great Lake System 

Potential Threat to the Great Lake System 

Because of the ecological, economical and cultural importance of the Great Lake System, there are several organizations that monitor and provide information on the status of aquatic invasive species. More general information can be found at the following; 

What You Can Do To Help 

There are several ways to help reduce the spread or initial introduction of invasive species into an area as well as help reduce or eradicate invasive species in the area. 

    1. Learn which invasive species are in your area and how to identify them 
    2. Report invasive species 
    3. Clean off watercrafts, trailers, fishing gear etc. particularly when moving between water bodies
    4. Don’t buy Round Goby bait (or another invasive species bait) 
    5. Don’t release non-native species into the environment (fish, plant, mammal etc)
    6. Learn proper removal protocol 

Further Information Developed by GBA 

The GBA is dedicated to providing our members with relative information on this topic. The following are website posts we have developed on this topic over the years. 

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