Which two species were notably introduced in Michigan for biological control of aquatic weeds but are now prohibited?

The two species that were notably introduced in Michigan for biological control of aquatic weeds and are now prohibited are grass carp and tilapia.

Grass carp were introduced as a means to manage aquatic vegetation effectively, given their appetite for various types of submerged weeds. However, their potential to overconsume native aquatic plants and disrupt local ecosystems has led to concerns about their impact on biodiversity and the balance of fish populations within bodies of water. Due to these ecological risks, they are now subject to stringent regulations to prevent undesirable consequences.

Tilapia were also considered for aquatic weed control because of their ability to consume plants. However, similar to grass carp, they pose risks related to ecological balance and the introduction of non-native species. This has resulted in the prohibition of their use for biological control in Michigan.

Both species illustrate the complexities of managing ecosystems and underline the importance of assessing ecological impacts before introducing non-native species for pest control.