Aquatic Invasion Discussion Questions

    Aquatic Invasion Discussion Questions

    1. What are the characteristics of an environment that is vulnerable to invasive species?

    Lack of biotic constraints: Natural predators or disease, which the invading organism had in its native environment are biotic constraints. Natural predators help control populations of their prey. Since an invasive species often has no natural predator in its non-native environment, its population rapidly increases. With a large population, it is easy for an invasive species to out-compete native species.

    Disturbances: Fire, construction, agriculture, etc., prior to the invasion cause a disruption in an ecosystem’s natural function and structure. A disrupted ecosystem is vulnerable to invasive species establishment.

    Proximity to potential sources of invasive species: Since people transport many non-native species, urban areas and recreational areas typically have a high number of invasive species. 

    New species often find their way into new ecosystems, but not all become nuisance species. In order for a non-native species to become an invasive species, it must harm and negatively impact its new environment.

    2. What can be done to control aquatic invasive species?

    Mechanical Control removes an invasive species by hand or with a machine. The process is often very labor intensive and needs multiple efforts. In Utah Lake, the Common Carp is being removed using boats, large nets, and hand labor to capture and remove about five million pounds of fish annually over a six year period. Trapping, electricity, trawling, or baiting may also be used.
    Chemical Control uses chemical applications to control invasive species. The chemical Rotenone is often used to treat water bodies infested with invasive fish species. However, chemicals like Rotenone, such as pesticides, herbicides, or other piscicides, are often not target-specific and can harm water resources as well as other plants and animals besides invasive species.

    Biological Control involves the release of a new species in the environment to control an invasive species. A biological control agent, the salt cedar leaf beetle (Diorhabda elongata), feeds on tamarisk. It has been released in nine western states including Utah in order to control tamarisk populations.

    3. What are specific procedures to protect against introduction of aquatic invasives?

    • Assume every water body is contaminated and that boats and equipment should always be considered contaminated
    • Eliminate water from all equipment before transporting anywhere
    • Remove all visible mud, plants, and fish/animals
    • Keep one set of equipment for use only on infested waters
    • Decontaminate equipment following each use, whenever possible, by cleaning and drying anything that came in contact with the water
    • Keep boat and equipment clean between trips and let dry for as long as possible
    • Do not release or put plants, fish or animals into a body of water unless they came out of that body of water
    • Report the finding of an aquatic invasive species to the Utah Division of Wildlife Resources at 801-538-4700

    4. Why are the definitions of invasive species sometimes unclear?

    Some non-native species are considered harmful and therefore invasive by some sectors of our society while others consider them beneficial. This discontinuity is reflective of the different value systems operating in our free society and  contributes to the complexity of defining the term invasive species. An example of this occurs with European honeybees, which produce honey and pollination services, but can cause problems by constructing hives in buildings or can be a serious human health concern for those that are highly allergic to their sting. However, most people would not consider the European honeybee as an invasive species because of the services (food and pollination) they provide. For more information see:

    5. How do aquatic invasive species affect water quality?

    Aquatic invasive species affect water quality through small changes in the ecosystem. These small changes have a significant, negative impact over time. One example of this is the Common Carp. This is a fish which feeds by browsing through underwater vegetation. This feeding uproots plants which muddies the water and destroys the food and cover needed by other fish. Another example of this is the Water Hyacinth. This is a plant which blocks light for photosynthesis, which greatly reduces oxygen levels in the water. This reduction in oxygen in turn reduces other underwater life such as fish and other plants, thus depleting biological diversity which alters an ecosystem’s animal community. (For more information see:

    6. What are some impacts of aquatic invasive species?  How do invasive species affect water resources and what are the associated effects?

    Aquatic invasive species have far-reaching affects. Invasive aquatic plants and animals destroy habitats in coastal waterways and interrupt the flow of water in inland desert irrigation canals. They clog storm canals leading to the flooding of homes and displace native species in our nation’s wetlands.  Furthermore, they compete with native species for resources, often leading to a decline in the population of native species. One example of this is seen in the competition between the native Cutthroat Trout and the nonnative Brown Trout in many rivers within Utah. Both are competing for the same food source, which is causing a decline in the native Cutthroat Trout population.

    7. Invasive species have a place in their native habitat.  When introduced to a new habitat, they are only doing what every other organism does: taking advantage of opportunities to survive and perpetuate their species.  How does knowing this change our actions in order to mitigate the spread of invasive species?

    Most invasive insects, marine invertebrates, and microorganisms are accidentally introduced. For this reason, most countries have many restrictions and regulations in place detailing how imported and exported products will be monitored.

    8. What are our future management, policy, and societal needs to lessen or adapt to the effects of invasive species as they alter aquatic ecosystems?

    The best way to limit impacts of non-native species is to prevent them from invading and becoming established in a new area. If this fails, eradication may still be possible, but generally only if the species is identified and treated quickly. Once established, efforts to restrict spread to uninfested areas can limit further damage.
    Controlling population sizes in heavily invaded areas can also reduce deleterious effects, but is unlikely to lead to eradication. Last, maintaining healthy natural communities, either by limiting human disturbance, or restoring of previously impacted areas, can limit opportunities for exotics to take hold.”

    9. What can you do to prevent the spread of invasive species?

    • Inspect your boat and equipment (waders, etc.).  Remove any plants or animals
    • Decontaminate boats and equipment before use in another waterbody
    • Drain water from the motor and all containers including, balast tank, bilge, and transom well and allow them to dry
    • Never transfer live aquatic species from one water body into another
    • Never dump aquarium plants or pets in lakes or streams
    • Don’t plant invasive species in your yard or garden
    • Get involved in a project to remove invasive species