Invasive species are organisms introduced to an ecosystem where they are not native, causing or likely to cause economic or environmental harm. These biological invaders are a major driver of biodiversity loss and contribute significantly to global plant and animal extinctions. The financial toll is immense, with worldwide costs surpassing $423 billion annually due to agricultural losses, infrastructure damage, and management expenses. Preventing the introduction of these species is the most effective and least costly defense against this growing threat.
Preventing Initial Introduction
Preventing the initial introduction of a non-native species is the most cost-effective defense against biological invasions. Governments and international bodies focus heavily on biosecurity measures and strict border controls to intercept potential invaders. This involves comprehensive inspection and quarantine protocols for imported goods, cargo, and agricultural products that can accidentally harbor organisms.
One major pathway for marine invasive species is the ballast water of large commercial ships. The International Maritime Organization (IMO) introduced the Ballast Water Management Convention, requiring ships to manage this water. The D-2 standard mandates that ships install specialized treatment systems to remove or neutralize harmful aquatic organisms before discharging the water. All ships are required to comply with this standard by 2024, significantly reducing the transport of microscopic organisms across oceans.
Land-based trade, particularly the nursery and pet industries, also creates significant pathways for introduction. Regulatory efforts now require businesses to adopt biosecurity protocols, such as quarantining new plant arrivals and ensuring equipment is thoroughly cleaned. This diligence prevents non-native plants, pests, or pathogens from entering the supply chain.
Early Detection and Rapid Response
When prevention efforts fail, Early Detection and Rapid Response (EDRR) strategies are employed to find new incursions before they become established. EDRR aims at eradicating a new population quickly. Because invasive species populations can grow exponentially, the window for successful eradication is often very small, making speed paramount.
Advanced surveillance technologies monitor large or remote areas. Remote sensing tools, such as hyperspectral imaging carried by drones or satellites, can analyze subtle differences in plant pigment and structure to map the presence of an invasive plant species. This data allows land managers to identify a threat before it is visible on the ground.
Citizen science networks are leveraged to expand surveillance across broad landscapes. Programs like EDDMapS and various smartphone apps allow the public to report sightings with GPS coordinates and photos. This crowdsourced data is verified by experts, quickly mobilizing local response teams for rapid assessment and control measures. Timely reporting is essential because eradication costs rise exponentially as an invader’s distribution increases.
Managing Established Invasive Species
Once an invasive species is widespread and established, managers must shift from eradication to control and population reduction, often through Integrated Pest Management (IPM). IPM uses a combination of control methods tailored to the specific species and environment. The three primary control methods are mechanical, chemical, and biological.
Mechanical control involves the direct removal of the invasive organism, ranging from hand-pulling in sensitive habitats to using heavy machinery for large-scale infestations. While highly selective, physical control is often expensive and can cause soil disturbance, which may create open ground for new invasive plants to colonize. For woody plants, the cut-stump method involves cutting the trunk and immediately applying a chemical to the stump to prevent re-sprouting.
Chemical control uses targeted applications of herbicides or pesticides, only after other options have been considered. Modern IPM protocols prioritize selective chemicals that target specific biological groups, or non-selective chemicals applied directly to the plant, such as injecting an herbicide into a tree trunk. This precision minimizes the risk of harming non-target native species and reduces the volume of chemical released into the environment.
Biological control introduces a natural enemy, such as an insect or pathogen, to keep the invasive species’ population in check. Before release, these biocontrol agents must undergo rigorous host specificity testing to ensure they will only attack the target invasive species. This testing prevents scenarios where a non-native control agent becomes invasive itself by preying on native wildlife.
How the Public Can Help Stop the Spread
Individual actions are a powerful defense against invasive species. The spread of aquatic invasive species is countered by the public following the “Clean, Drain, Dry” protocol for watercraft and fishing gear. This involves thoroughly cleaning all visible mud, plants, and animals, draining all water on land, and completely drying the equipment before entering a new water body.
The release of unwanted pets and aquarium contents is a major pathway for introduction. Pet owners are encouraged never to release exotic animals, fish, or aquarium plants into natural areas, as these organisms often thrive without natural predators. Responsible alternatives include returning the animal to a pet store, rehoming it, or contacting a veterinarian for humane euthanasia.
Home gardeners can contribute by choosing native plants instead of non-native ornamentals that may escape cultivation and become invasive. Native plants are adapted to local conditions and provide food sources and habitat for local insects and wildlife, strengthening the native ecosystem’s resilience.
Citizens can act as an early warning system by reporting any unusual or suspected invasive species sightings to local resource agencies or through mobile apps like IveGot1. This participation supports the EDRR framework, providing the timely data needed to control a new invasion before it takes hold.