A serious threat to the Lake Erie ecosystem is invasive species. Many of these species have entered the Great Lakes through the ballast water of ships. At least 25 non-native species of fish have entered the Great Lakes since the 1800s, including:
- Rusty crayfish
- Spiny water flea
- Round goby
- Tubenose goby
- Sea lamprey
- Eurasian ruffe
- White perch
- Zebra mussel
- Quagga mussel
Weren’t mussels a big issue at one time?
Zebra mussels arrived in North America in 1988. Quagga mussels invaded the Great Lakes in 1989 and are now found throughout Lake Erie. Quagga mussels are slightly larger than the zebra mussels and have a higher tolerance for cold water. They disrupt the Lake’s ecosystem by competing with many native algae since they eat many of the same organics, but they do not eat phosphorus. Such conditions allow cyanobacteria (also known as blue-green algae) to thrive. Cyanobacteria can release toxins into the Lake water that pose a hazard to swimmers and other recreational users.
Why am I hearing about Asian carp?
Based on the problems caused by non-native species, scientists are closely watching other species that have invaded nearby ecosystems. Asian carp are of particular concern because they have been found in nearby waterways that eventually connect to the Great Lakes. Asian carp entered the Mississippi River watershed after floods in the mid-1990s allowed them to escape from fish-rearing and wastewater treatment ponds in the southern United States, where they had been brought in to remove algae and organic matter. These carp are filter feeders that consume huge volumes of plankton from the food chain, starve out the young of native species, and quickly spread and overwhelm resident populations of game fish. If the Asian carp enter the Great Lakes watershed it will produce another huge change in the ecosystem. The U.S. Environmental Protection Agency(EPA) and state and local agencies have constructed a permanent electric barrier to prevent the fish from entering the Great Lakes through Lake Michigan.