Environmental DNA Reveals Hidden Invasive Species in Waterways

Invasive species are a growing threat to Finland’s native nature. They can outcompete native species, spread diseases, and disrupt the balance of ecosystems. The challenge is that invasive species are often detected only after they have already spread and started affecting the environment.

Environmental DNA, or eDNA, offers an effective solution to this problem. It enables precise and rapid identification of invasive species often before they have a chance to spread widely or cause significant harm. Early detection allows timely decisions to support conservation and control efforts.

Example: The Pumpkinseed Sunfish — Effective Mapping Before Population Growth

Puro Analytics carried out a survey on the presence of the pumpkinseed sunfish (Lepomis gibbosus) in cooperation with Kala- ja Vesitutkimus Oy. The pumpkinseed is a species native to North America that has likely entered Finnish waters as a result of the aquarium trade.

Although this small fish may appear harmless, it reproduces efficiently and can outcompete native species and degrade water quality. The species is small and tends to stay hidden, which makes detection with traditional methods challenging. When the population is still small, individuals may go completely unnoticed.

With environmental DNA, the pumpkinseed sunfish can be detected even when the population is still small—when control efforts are easiest and most effective.

How Does eDNA Detect Invasive Species in Water Environment?

Environmental DNA is based on the idea that organisms leave traces of their genetic material in the environment. In the case of fish, this can include skin cells, mucus, or feces that are released and dispersed through the water. DNA is first filtered from water samples, then isolated and analyzed in a laboratory to determine whether a specific species is present in the area.

For the pumpkinseed sunfish, this means:

• Detecting the species before it forms a large population

• Locating where exactly the invasive species occurs (depending on water flow patterns)

• Monitoring the effectiveness of control measures over time

Effective Invasive Species Control Starts with Up-to-Date Information

The earlier an invasive species is detected, the more likely its spread can be prevented. Environmental DNA enables systematic monitoring, particularly in areas where precision and reliability are crucial.

These include, for example:

• Natura sites and other sensitive protected water areas

• Ports and heavily trafficked waterways (often the first points of introduction for invasive species)

• Municipal and state water management programs

• Permit processes and fisheries assessments

Puro Analytics — Supporting Invasive Species Management

Puro Analytics provides expert environmental DNA analysis that reveals even those invasive species hiding beneath the surface or otherwise difficult to detect. Our services help authorities, companies, planners, and environmental organizations make informed decisions at the right time. With us, you get reliable results and a clear picture of what is truly happening in your water systems.