Invasive Species in Nevada: Threats to Ecosystems

By: Jennie Johnson

Nevada's diverse ecosystems, from arid deserts to lush wetlands, face significant threats from invasive species. These non-native organisms disrupt local habitats, outcompeting native species and altering ecosystems. Here’s a look at some of the invasive species in Nevada, detailing their impacts, the challenges they pose, and the efforts to manage them.

1. Grass Carp (Ctenopharyngodon idella)

Grass carp, introduced to control aquatic vegetation, have become a significant problem in Nevada's waterways, particularly in lakes and reservoirs. They consume large amounts of vegetation, leading to the depletion of native aquatic plants, which are crucial for maintaining healthy aquatic ecosystems. This consumption destabilizes habitats, increases water turbidity, and disrupts the spawning grounds for native fish. By reducing the availability of aquatic plants, grass carp also diminish food resources for invertebrates and other aquatic animals.

Management Efforts

Controlling grass carp populations involves careful management strategies, including the use of barriers to prevent their spread and monitoring their impact on local ecosystems. Biologists sometimes introduce sterile grass carp (triploids) to ensure they do not reproduce. In some cases, physical removal or relocation is used to reduce their numbers.

Impacted Locations

In Nevada, grass carp are particularly problematic in the Truckee and Carson River basins and various reservoirs used for irrigation and recreation. Their presence in these water bodies threatens the ecological balance and the health of aquatic habitats.

2. Tamarisk (Tamarix spp.)

Impact and Challenges

Tamarisk, or saltcedar, is a shrubby tree that invades riparian zones, consuming large quantities of water and reducing availability for native plants and animals. It also increases soil salinity, making environments inhospitable for native vegetation. Tamarisk's dense growth alters stream flows, increases the risk of wildfire, and creates a monoculture that displaces diverse plant communities. This change impacts wildlife that depends on native riparian habitats for food and shelter.

Management Efforts

Efforts to control tamarisk include mechanical removal, chemical treatments, and biological control using insects like the tamarisk beetle (Diorhabda spp.), which feeds on tamarisk leaves. Restoration projects often follow tamarisk removal to replant native vegetation and restore ecological balance.

Impacted Locations

Tamarisk is widespread in Nevada, especially along the Colorado River, the Virgin River, and in the Lahontan Valley. Its presence in these areas has led to significant changes in riparian ecosystems, affecting water availability and habitat quality for native species.

3. Quagga Mussel (Dreissena rostriformis bugensis)

Impact and Challenges

Quagga mussels are small freshwater mollusks that attach to surfaces in dense clusters. In Nevada, they clog water intake systems, outcompete native mussels, and disrupt aquatic ecosystems by filtering out plankton, which is essential to the aquatic food web. Their presence can lead to significant economic costs for maintaining water infrastructure and managing their ecological impacts.

Management Efforts

Managing quagga mussels involves regular monitoring of water bodies, boat inspection and cleaning programs to prevent their spread, and the use of chemical treatments in water systems. Public awareness campaigns are critical in educating boaters and water users about preventing the spread of these mussels.

Impacted Locations

Quagga mussels have heavily infested Lake Mead, Lake Mohave, and the Colorado River system in Nevada. These invasions threaten water supply infrastructure and native aquatic species, altering the ecology of these important water bodies.

4. Cheatgrass (Bromus tectorum)

Impact and Challenges

Cheatgrass is an invasive annual grass that spreads rapidly across Nevada's sagebrush steppe. It competes with native plants for resources and dramatically alters fire regimes by creating a continuous, highly flammable fuel layer. This leads to more frequent and intense wildfires, which can destroy native plant communities and give cheatgrass a competitive advantage.

Management Efforts

Efforts to control cheatgrass include the use of herbicides, controlled burns, and reseeding with native or less flammable plant species. Fire prevention strategies and public education about reducing wildfire risks are also critical components of managing cheatgrass.

Impacted Locations

Cheatgrass is prevalent throughout Nevada, particularly in the Great Basin region. Its presence has transformed large areas of sagebrush steppe into fire-prone landscapes, threatening wildlife habitats and the stability of these ecosystems.

5. Red Swamp Crayfish (Procambarus clarkii)

Impact and Challenges

The red swamp crayfish is an aggressive feeder that consumes aquatic plants, invertebrates, and small fish. In Nevada, they disrupt food webs and lead to the decline of native species. Their burrowing activities can damage stream banks and levees, increasing erosion and altering water flow patterns. Their predation on aquatic vegetation can degrade habitat quality for other species.

Management Efforts

Managing red swamp crayfish involves trapping, habitat modification, and public education to prevent their spread. Some areas have implemented targeted removal programs to reduce their population and mitigate their impact on local ecosystems.

Impacted Locations

In Nevada, red swamp crayfish are found in various freshwater systems, including ponds, lakes, and slow-moving streams. They are particularly problematic in the wetlands and agricultural waterways of southern Nevada, where their impact on local ecosystems and infrastructure is most severe.

6. Russian Olive (Elaeagnus angustifolia)

Impact and Challenges

Russian olive is a thorny shrub or small tree that invades riparian areas, displacing native vegetation and reducing biodiversity. It forms dense thickets that can block access to waterways for wildlife and increase fire risk. Russian olive also alters soil chemistry by fixing nitrogen, making it difficult for native plants to reestablish once the tree has invaded.

Management Efforts

Control methods for Russian olive include mechanical removal, herbicide application, and prescribed burns. Restoration efforts often follow to replant native species and restore habitat quality. Public awareness and prevention measures are also essential to control its spread.

Impacted Locations

Russian olive is found throughout Nevada, particularly along the Humboldt River and in the Carson River watershed. Its dense thickets have altered the structure and function of riparian ecosystems, making it a significant concern for habitat conservation.

7. American Bullfrog (Lithobates catesbeianus)

Impact and Challenges

The American bullfrog is a large, voracious predator that consumes a wide variety of prey, including insects, fish, small mammals, and other amphibians. In Nevada, they outcompete and prey on native frog populations, contributing to their decline. Bullfrogs also have a significant impact on the aquatic ecosystems they invade, disrupting local food webs and altering habitat conditions.

Management Efforts

Management strategies for bullfrogs include habitat modification, trapping, and removal. Some areas employ exclusion techniques to prevent their spread, such as barriers and modified water levels. Public education on the impact of bullfrogs and the importance of not releasing them into the wild is crucial.

Impacted Locations

Bullfrogs are widespread across Nevada, particularly in the wetlands and freshwater systems of the Las Vegas Valley and the Truckee River basin. Their presence in these areas threatens the diversity and stability of local aquatic ecosystems.

8. Nutria (Myocastor coypus)

Impact and Challenges

Nutria are large, semi-aquatic rodents that cause extensive ecological damage through their feeding and burrowing behaviors. They consume aquatic plants, leading to the destruction of wetlands and increasing erosion. Their burrowing into levees, dikes, and riverbanks weakens these structures and increases the risk of flooding. Nutria also outcompete native wildlife and are potential carriers of diseases.

Management Efforts

Efforts to control nutria in Nevada involve trapping and removal, habitat modification, and public awareness campaigns to report sightings and prevent their spread. Restoration of damaged habitats is also critical to mitigate their impact.

Impacted Locations

In Nevada, nutria have been reported in southern areas, especially in the Las Vegas Wash and Wetlands Park. Their presence in these wetland habitats poses significant risks to the ecosystem and water management infrastructure.

9. New Zealand Mud Snail (Potamopyrgus antipodarum)

Impact and Challenges

New Zealand mud snails reproduce rapidly and can reach extremely high densities, outcompeting native snails and invertebrates for food. Their dense populations can disrupt food webs and degrade aquatic habitats. These snails are highly resilient, capable of surviving in a wide range of environmental conditions and spreading through various water systems.

Management Efforts

Managing New Zealand mud snails includes preventing their spread through public education and boat cleaning protocols. Regular monitoring of water bodies and targeted removal efforts, where feasible, are also essential. Biological control and habitat management are areas of ongoing research to find effective long-term solutions.

Impacted Locations

New Zealand mud snails are found in several Nevada rivers and streams, including Lake Tahoe, the Truckee River and the Carson River. They are of particular concern at lake Tahoe where prevention is serious and the snails could impact the clarity of the water. Their presence in these water bodies threatens native aquatic life and complicates efforts to maintain healthy aquatic ecosystems. 

10. Eurasian Watermilfoil (Myriophyllum spicatum)

Impact and Challenges

Eurasian watermilfoil is an invasive aquatic plant that forms dense mats on the surface of water bodies. It crowds out native plants, alters water quality, and hinders recreational activities such as boating and fishing. The thick growth of watermilfoil can deplete oxygen levels in the water, harming fish and other aquatic life.

Management Efforts

Control methods for Eurasian watermilfoil include mechanical removal, the use of herbicides, and biological control using certain species of fish or insects that feed on the plant. Regular monitoring and rapid response to new infestations are crucial to preventing the spread of this invasive plant.

Impacted Locations

In Nevada, Eurasian watermilfoil has invaded various lakes, ponds, and slow-moving streams, particularly in the Carson River and Lake Tahoe basins. Its presence in these water bodies poses a threat to local ecosystems and recreational activities.

11. Yellow Starthistle (Centaurea solstitialis)

Impact and Challenges

Yellow starthistle is an aggressive weed that infests grasslands, rangelands, and disturbed areas. It competes with native grasses and forbs for resources, reducing forage quality for livestock and wildlife. The plant's sharp spines deter animals from grazing and create barriers that limit movement. Yellow starthistle can also alter soil moisture and nutrient levels, further causing disadvantages to native plant species.

Management Efforts

Managing yellow starthistle involves the use of herbicides, mechanical removal, and biological control agents such as insects that specifically target the plant. Restoration efforts to reestablish native vegetation are also important in areas where starthistle has been removed.

Impacted Locations

Yellow starthistle is widespread across Nevada, particularly in the northern and western parts of the state, including the Great Basin. It thrives in disturbed areas and rangelands, where its dense growth reduces habitat quality for both wildlife and livestock.

12: Red-eared Slider (Trachemys scripta elegans)

Impact and Challenges

The Red-eared Slider, a popular pet turtle, has become a problematic invasive species in Nevada. Originally native to the southeastern United States, it has been widely introduced across the country, including in Nevada, through the pet trade and subsequent release by owners. Red-eared sliders outcompete native turtle species for food, basking sites, and nesting areas. Their aggressive feeding habits allow them to dominate local ecosystems, leading to declines in native turtle populations.

Management Efforts

Controlling the spread of Red-eared Sliders in Nevada involves several strategies including public education; informing pet owners about the ecological impacts of releasing turtles into the wild and promoting responsible pet ownership. Initiatives like "adopt, don’t release" campaigns help reduce the number of released pets. Population Control is important in areas where the turtles are established, efforts may include trapping and removal. Finally, supporting the recovery of native turtle species through conservation programs and habitat restoration projects.

Impacted Locations

In Nevada, Red-eared Sliders are found in various aquatic habitats, including urban and suburban ponds, lakes, and rivers. They are particularly common in the Las Vegas Valley and other developed areas where they have been released by pet owners. Their presence in these habitats threatens native turtle species like the Mojave Desert Tortoise (Gopherus agassizii) and Western Pond Turtle (Actinemys marmorata). This turtle was rescued and relocated last fall at Virginia Lake in Reno.

Bonus: Toxic Algae Blooms/Harmful Algae Blooms

Toxic algae blooms, commonly caused by cyanobacteria, are a growing concern in Nevada’s water bodies. These blooms can produce harmful toxins that pose significant risks to both humans and wildlife. While not always classified as invasive, some species of algae can invade new habitats and proliferate under favorable conditions. In Nevada, blooms have been reported in key locations such as Lake Mead, Washoe Lake, and Lahontan State Park. These blooms thrive in nutrient-rich waters, often fueled by agricultural runoff, wastewater discharge, and warm temperatures. They disrupt aquatic ecosystems by depleting oxygen levels, leading to fish kills, and can contaminate drinking water sources. The presence of toxic algae affects recreational activities like swimming and fishing and poses serious health risks to pets and humans who come into contact with or ingest the contaminated water. Managing these blooms involves monitoring water quality, reducing nutrient inputs, and educating the public on the dangers and prevention of toxic algae outbreaks.

Invasive species in Nevada pose significant challenges to the health and sustainability of its ecosystems. Effective management and mitigation efforts are crucial to preserving the state's biodiversity and natural resources. Public awareness and proactive management are key to controlling these invasions and protecting Nevada's unique landscapes.

This overview highlights the diverse and severe impacts of invasive species in Nevada. Each species demonstrates how non-native organisms can disrupt the balance of local ecosystems, leading to widespread ecological and economic consequences. Restoration efforts, like those taking place at Rosewood Nature Study Area, demonstrate how we can be stewards of our Nevada parks and open spaces.

__________________________

Sources:

General Information on Invasive Species in Nevada

1. Nevada Department of Wildlife - Invasive Species

   - Overview of invasive species in Nevada and their impact on ecosystems.

   - Nevada Department of Wildlife (http://www.ndow.org/Nevada_Wildlife/Invasive_Species/)

2. Nevada Invasive Species Council

   - Resource for information on invasive species management and prevention efforts in Nevada.

   - Nevada Invasive Species Council (https://nevadainvasivespecies.org/)

Specific Invasive Species

Grass Carp

3. Nevada Department of Wildlife - Grass Carp

   - Information on grass carp and management practices.

   - Nevada Department of Wildlife - Grass Carp (http://www.ndow.org/Nevada_Wildlife/Fish/Grass_Carp/)

4. Invasive Species: Grass Carp (PDF):

   - Detailed factsheet about the grass carp's impact and management.

   - Invasive Species - Grass Carp (PDF) (https://www.fs.fed.us/database/feis/animals/fish/ctid/all.html)

Tamarisk

5. USGS - Tamarisk (Saltcedar):

   - Comprehensive overview of tamarisk’s impact and control measures.

   - USGS - Tamarisk (https://www.usgs.gov/centers/western-ecological-research-center/science/invasive-tamarisk-impacts-and-management)

6. Tamarisk Coalition:

   - Information and resources for managing tamarisk invasions.

   - Tamarisk Coalition (https://riversedgewest.org/)

Quagga Mussel

7. Nevada Department of Wildlife - Quagga Mussel:

   - Information on the distribution and impact of quagga mussels in Nevada.

   - Nevada Department of Wildlife - Quagga Mussel (http://www.ndow.org/Nevada_Wildlife/Invasive_Species/Quagga_Mussels/)

8. National Park Service - Quagga Mussel:

   - Overview of the quagga mussel issue in Lake Mead and other affected areas.

   - National Park Service - Quagga Mussel (https://www.nps.gov/lake/learn/nature/quaggamussel.htm)

Cheatgrass

9. Cheatgrass Management Handbook:

   - Guide to managing cheatgrass in the Great Basin.

   - Cheatgrass Management Handbook (PDF) (https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5410110.pdf)

10. USDA - Cheatgrass:

    - Information on the impact of cheatgrass and management techniques.

    - USDA - Cheatgrass (https://www.fs.fed.us/database/feis/plants/graminoid/brotec/all.html)

Red Swamp Crayfish

11. USGS - Nonindigenous Aquatic Species Database: Procambarus clarkii:

    - Detailed information on the red swamp crayfish and its distribution.

    - USGS - Procambarus clarkii (https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=217)

12. Nevada Department of Wildlife - Crayfish:

    - Overview of crayfish issues in Nevada.

    - Nevada Department of Wildlife - Crayfish (http://www.ndow.org/Nevada_Wildlife/Crayfish/)

Russian Olive

13. Colorado State University - Russian Olive:

    - Fact sheet on Russian olive, including its impact and management.

    - Colorado State University - Russian Olive (https://extension.colostate.edu/topic-areas/natural-resources/russian-olive-6-506/)

14. Invasive Species - Russian Olive:

    - Resources and information on controlling Russian olive in riparian areas.

    - Invasive Species - Russian Olive (https://www.invasivespeciesinfo.gov/terrestrial/plants/russian-olive)

American Bullfrog

15. USGS - American Bullfrog

    - Comprehensive overview of the bullfrog’s ecology and impact.

    - USGS - American Bullfrog (https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=71)

16. California Invasive Plant Council - Bullfrog

    - Information on the impacts and management of bullfrogs.

    - California Invasive Plant Council - Bullfrog (https://www.cal-ipc.org/plants/profile/lithobates-catesbeianus-profile/)

Nutria

17. USDA APHIS - Nutria

    - Detailed guide on the impacts and management of nutria.

    - USDA APHIS - Nutria (https://www.aphis.usda.gov/aphis/ourfocus/wildlifedamage/operational-activities/nutria)

18. Nevada Department of Wildlife - Nutria

    - Information on nutria in Nevada, including sightings and management.

    - Nevada Department of Wildlife - Nutria (http://www.ndow.org/Nevada_Wildlife/Nutria/)

New Zealand Mud Snail

19. New Zealand Mud Snail Management and Control

    - Strategies and guidelines for managing New Zealand mud snails.

    - New Zealand Mud Snail Management (PDF) (https://www.fws.gov/southwest/federal_assistance/PDFs/New_Zealand_Mudsnail_Management_Control.pdf)

20. USGS - New Zealand Mud Snail

    - Information on the distribution and ecological impact of New Zealand mud snails.

    - USGS - New Zealand Mud Snail (https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1008)

Eurasian Watermilfoil

21. USDA - Eurasian Watermilfoil

    - Overview of Eurasian watermilfoil, its impacts, and control measures.

    - USDA - Eurasian Watermilfoil (https://www.fs.fed.us/database/feis/plants/forb/myrspic/all.html)

22. Aquatic Nuisance Species Task Force - Eurasian Watermilfoil

    - Resources and information on managing Eurasian watermilfoil.

    - Aquatic Nuisance Species Task Force - Eurasian Watermilfoil (https://www.anstaskforce.gov/Species%20fact%20sheets/Eurasian_watermilfoil.pdf)

Yellow Starthistle

23. USDA - Yellow Starthistle

    - Detailed information on yellow starthistle and its management.

    - USDA - Yellow Starthistle (https://www.fs.fed.us/database/feis/plants/forb/censol/all.html)

24. California Invasive Plant Council - Yellow Starthistle

    - Resources and strategies for controlling yellow starthistle.

    - California Invasive Plant Council - Yellow Starthistle (https://www.cal-ipc.org/plants/profile/centaurea-solstitialis-profile/)

Red-eared Slider

25. USGS - Red-eared Slider

    - Information on the ecology, distribution, and impacts of red-eared sliders.

    - USGS - Red-eared Slider (https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1261)

26. Invasive Species Specialist Group - Red-eared Slider*

    - Overview of the red-eared slider’s invasive status and control methods.

    - Invasive Species Specialist Group - Red-eared Slider (http://www.iucngisd.org/gisd/species.php?sc=71)

About the Author

Jennie is serving her third Americorps VISTA term as the Wetland Restoration Outreach Coordinator. She is from right here in Reno and went to the University of Nevada, Reno for a degree in Cultural Anthropology. She’s excited to use her marketing background to teach people about the parks and opportunities in their community. She enjoys running, hiking, sunshine and events such as Moms on the Run and the American River Half Marathon.