The unseen threat of aquatic invasive species in US inland waters has emerged as a critical environmental challenge, silently disrupting ecosystems and economies. Invasive species introduced by human activities outcompete native organisms and cause significant environmental and economic damage, costing the U.S. about $120 billion annually. Aquatic invaders like zebra mussels and Asian carp are major contributors, threatening biodiversity, water quality, and recreational opportunities across various water bodies. Urgent action is needed to address this issue.

Pathways of Invasion

The unseen threat of aquatic invasive species often begins with human-mediated pathways. Recreational boating, aquaculture, and the aquarium trade are primary vectors. Zebra mussels (Dreissena polymorpha) entered the Great Lakes in the 1980s via ship ballast water and rapidly spread to inland waters. Boaters can unknowingly carry invasive species like hydrilla on trailers, and aquarium releases can introduce species like the northern snakehead. One thousand eight hundred six individual anglers (70%) of the 2576 survey participants in the 13 US states that border the Great Lakes and upper Mississippi River basins fished in more than one county during the survey year.

Ecological Impacts

The unseen threat of aquatic invasive species has serious ecological repercussions, upsetting food webs and decreasing biodiversity. Invasive species like the round goby and zebra mussels in the Great Lakes outcompete native fish and reduce food availability, leading to declines in species such as darters and sculpins. A 2024 report from Michigan Sea Grant found that lakes with zebra mussels have three times higher levels of Microcystis, a toxic algae that affects water quality and native organisms. To maintain ecosystem equilibrium, these disturbances highlight how urgently aquatic invasive species must be addressed.

a. Biodiversity Loss

Because aquatic invasive species reduce biodiversity, they represent an unseen hazard. Similar to the US, 200 cichlid fish species in Lake Victoria became extinct as a result of the introduction of Nile perch. Native plants are shaded, and habitat variety is reduced by dense mats of invasive species, such as Eurasian watermilfoil. According to the U.S. EPA, 70% of native aquatic species will become extinct this century, and 42% of endangered species will suffer major harm from invasive species. This loss of biodiversity not only reduces ecosystem resilience but also makes it more difficult for native species to adapt to shifting environmental conditions.

b. Food Web Alterations

Aquatic invasive species cause invisible harm by upsetting food webs. Because they sometimes have no natural predators in their new habitats, invasive species can proliferate unchecked. The introduction of peacock bass in Lake Gatun, Panama, simplified food webs, impacting zooplankton and insect populations, similar to trends observed in the US. Rusty crayfish occurrences have increased from 7% of all crayfish records collected during the first 20 years of their invasion (1965–1984) to 36% of all records during the last 20 years, and rusty crayfish have replaced the northern clearwater crayfish and virile crayfish as the most dominant member of the contemporary crayfish fauna. These changes disrupt the flow of nutrients and energy, endangering the stability of aquatic ecosystems.

Also Read: The Impact Of Invasive Species On Native Biodiversity And Ecosystem Services

Economic Consequences

The unseen threat of aquatic invasive species has a severe financial impact on everything from fisheries to infrastructure. Maintenance costs for municipalities are in the millions when quagga and zebra mussels choke water intake lines. Managing invaders like quagga and zebra mussels, which can harm power plants, water systems, boats, and docks, is projected to cost $500 million annually. Additionally, they have a detrimental effect on fishing and boating for pleasure, which lowers tourism-related income. Resources from other conservation initiatives must be diverted to monitor and eradicate them in order to control their spread.

a. Infrastructure Damage

Invasive species like quagga mussels pose significant risks to infrastructure. Their ability to attach to surfaces using byssal threads clogs pipes and damages boat motors. Lake Mead and its surrounding community spend over $20 million annually to combat mussel infestations. This infrastructure damage not only increases operational costs but also disrupts the flow of water for agricultural and urban use, underscoring the need for proactive measures to mitigate the threat posed by aquatic invasive species.

b. Fisheries and Recreation

Recreational activities and fisheries are significantly impacted by the unseen threat of aquatic invasive species. Native fish are outcompeted by invasive species, such as Asian carp, which lowers output in both commercial and recreational fisheries. Chick’s team examined Corps data collected from 1994 to 2013 and discovered that sport fish populations decreased by almost 30% in two carp-infested locations on the Mississippi River and one on the Illinois River, which had an impact on fishing-dependent local economies. Water hyacinths and other invasive species that obstruct waterways, make boating difficult, and restrict access to recreational areas exacerbate economic losses.

Also Read: Researchers Propose Innovative Strategies To Combat Florida’s Burmese Python Invasion

Management and Prevention Strategies

Because aquatic invasive species pose an invisible threat, a multimodal approach that includes prevention, early identification, and prompt treatment is required. Campaigns to raise awareness, such as “Clean, Drain, Dry,” teach boaters how to stop the spread of invasive species. With an emphasis on early identification, the EPA has invested over $50 million in more than 80 GLRI programs since 2010 to battle invasive species. Researchers can detect invaders early thanks to technologies like environmental DNA (eDNA) sampling, which guarantees timely containment to safeguard native ecosystems.

Regular monitoring, supported by eDNA, is crucial for managing aquatic invasive species. In 2023, the USGS will continue monitoring 109 sites in the National Water Quality Network (NWQN), covering important environmental settings, aiding surveillance, and enabling rapid response to new invasions. Innovative strategies, like using biological controls and physical removal, are being tested. Biological control using a native weevil is the safest way to control Eurasian watermilfoil, but it can be costly depending on the degree of infestation and the effectiveness of treatment. Converting invasive plants into biochar for wastewater treatment offers a sustainable resource solution.

Human Health Implications

The unseen threat of aquatic invasive species extends to human health, particularly through the proliferation of harmful algal blooms. Zebra mussels, by filtering nutrients, promote blooms of toxic cyanobacteria like Microcystis, which produce microcystins linked to liver damage. Even while many human illnesses may survive and spread in aquatic ecosystems without any hosts, it is crucial to keep in mind that more than 61% of all known human infectious pathogens are zoonotic, and around 75% of newly emerging human pathogens are zoonotic. These health consequences draw attention to the need for comprehensive management as well as the invasive species’ broader impacts.

Also Read: Policy And Legislation In Invasive Species Management: A Global Perspective

Conclusion

A major but sometimes disregarded threat to inland waters in the United States is aquatic invasive species. Local economy are strained, native species are harmed, and ecosystems are disturbed. More awareness and more robust preventative measures are needed to protect these waters. Our freshwater ecosystems can be preserved for future generations if we act today.

Also Read: Asian Hornet Invasion In Britain Sparks Alarm For Native Pollinators