Invasive Mussels in Thunder Bay National Marine Sanctuary

February 2020

Invasive species are organisms that cause ecological or economic harm in environments where they have been introduced. They can make their way to ocean and Great Lakes ecosystems through the ballast water of oceangoing ships, intentional and accidental releases of aquaculture species, aquarium specimens or bait, and other means. Today, meet two invasive species in Thunder Bay National Marine Sanctuary.


[Divers swim alongside a shipwreck. Instrumental music plays in the background, and a blue banner with text appears in the bottom left corner]

Thunder Bay National Marine Sanctuary protects the history within Lake Huron.

[The camera switches between shots of divers in Thunder Bay]

To date, nearly 100 shipwrecks have been discovered within the sanctuary boundaries.

These vessels tell the stories of our maritime past and serve as living museums.

[Camera pans over footage of a shipwreck covered in tiny mussels]

Today, these sunken ships are threatened by a tiny menace: invasive mussels.

[An aerial view of the Great Lakes is shown, with two large vessels sailing between small islands]

A few decades ago, zebra and quagga mussels were introduced to the Great Lakes, likely by ocean vessels dumping ballast water.

[Schools of fish swim around an underwater structure covered in mussels]

Of the many invasive species in the Great Lakes, zebra and quagga mussels have had the greatest negative impact on sanctuary resources.

[A diver swims with a flashlight pointed at a shipwreck underwater, which is also covered in mussels]

These mussels have an affinity for hard surfaces such as boats, docks, buoys, and submerged archaeological resources.

[Camera pans over the shipwreck covered in mussel colonies]

Zebra and quagga mussel colonization makes accurate data collection of the wrecks difficult for archaeologists.

[A boulder underwater is shown, with a large crack down the middle filled with mussels. A diver swims along the lake bottom in the background]

Archaeologists are not the only ones having a hard time with the introduction of mussels to the Great Lakes.

[Camera pans to an up-close shot of a mussel colony]

These invasive mussels filter out small zooplankton, leaving less food for many native invertebrates.

[A colony of mussels is pictures on the bottom of the lake]

That can have repercussions all the way up the food web.

[Video cuts back to footage of the diver swimming alongside a shipwreck]

Thunder Bay National Marine Sanctuary is actively seeking research partners to conduct work connected to invasive species as a key issue.

[Screen fades to black, and credits roll. The Earth is Blue logo is pictured, and the website is listed below. The logos for NOAA and National Marine Sanctuaries slide onto the screen, followed by credits:
Cinematography: Nick Zachar/ NOAA
Editor: David Ruck/ NOAA
Music: Matt McIntosh/ NOAA
Shannon Shikles/ NOAA
Universal Production Music]