Animals can be invasive too! Asian carp are an example of a nonnative species
that can replace native fish populations. These carp are threatening to upset the
balance of Lake Erie reducing populations of fish such as walleye. One model
suggests that Asian carp could eventually account for up to 34% of the total fish
weight in the lake.
Bighead and silver carp, imported from Asia to control algae, compete with native fish that eat microscopic plants and animals. Another Asian species, grass carp, will feast on aquatic vegetation that provides crucial habitat and spawning grounds. They have been found in Lakes Erie, Michigan and Ontario, although it’s uncertain how many there are or how widely they have spread.
If you visited Lake Erie this summer there is a chance you saw algal blooms. Unfortunately, you didn’t need to go that far, as we had a harmful algal bloom detected on the Maumee River right here in Defiance. 🙁
Having a bloom such as this on moving water demonstrates that we have a long way to go in reducing the nutrients entering our streams and rivers. These algal blooms occur when there is excess phosphorus & nitrogen, as algae and cyanobacteria feed on these nutrients. In addition, warmer water can increase the blooms making them more likely to occur in stagnant systems, usually not moving water flowing down a river! The Defiance Department of Health responded by posting warning signs at access points along the River.
Fixing the Harmful Algal Bloom problem will not occur overnight, but Ohio has signed an agreement with some specific targets for reducing phosphorus inputs. We have committed to a 20% reduction by 2020 and a 40% reduction by 2025. Scientists are working to identify target areas and strategies that will be most effective by using computer models and data such as land use, soil type, and conservation practices to pinpoint phosphorus hotspots.