The zebra mussel is a highly invasive species that was accidentally introduced to the Great Lakes region of the United States in the 1980s. The map below shows the distribution of zebra mussels in 2010. • Zebra mussel location What is the primary reason the large-scale spread of zebra mussels concerns scientists? Zebra mussels out-compete native mussel species. © Zebra mussels are a freshwater species. Zebra mussels are a desired food for humans. Zebra mussels are eaten by some fish and birds.

Although the map showing the distribution of mussels in not included but the question can be answered based on general understanding of invasive species. The answer is:

Zebra mussels out-compete native mussel species.

Explanation:

Invasive species in biology refers to the species of an organism that is foreign to a particular area/location with an ability to grow very rapidly to the point of being a threat to the local species of organisms that are native to the area.

This is the case of the Zebra mussel, which was accidentally introduced to the Great Lakes region of the United States in the 1980s. It is a major concern for scientists (like every other invasive species) because of its potential to outgrow and outcompete native mussel species i.e mussel species naturally found in the lake.