Quirks & Quarks

Invasive spiny water flea comes with a big cost

The spiny water flea was introduced in the 1980s and migrated into smaller lakes, eating algae-eating Daphnia and disrupting lake ecosystems

European water flea is wiping out important invertebrates in North American waters

Spiny water flea - the long spiny tail is a defence against small fish. (Jake Walsh)
The spiny water flea was first spotted in the Great Lakes in the early 1980's. The tiny zooplankton had arrived in the St. Lawrence Seaway in the ballast water of Russian ships. By 2009, it had found its way to various inland waterways, including Lake Mendota in Wisconsin, where it has contributed to a decline in the water quality there.

A new study by Dr. Jake Walsh, a researcher in the Center for Limnology at the University of Wisconsin, found that the spiny water flea has a huge appetite for the native Daphnia zooplankton. Daphnia were previously able to keep the lake clean and clear by consuming algae, until the arrival of the spiny water flea, which devoured the Daphnia.

Through various models and estimates, the study was also able to assign a dollar value for clear water to the residents of the lake area ($140 million), as well as a cost for a clean up ($80 to $160 million). The study demonstrated that apart form the ecological cost, there is also a monetary price that comes with invasive species.  

Related Links

- Paper in PNAS
- University of Wisconsin-Madison release
- Washington Post story