Zebra Mussel

Description

Zebra Mussels are small, freshwater mollusks identifiable by their distinctive black, brown, and white zigzag patterns. While they bear a resemblance to Quagga Mussels (another invasive mussel to Canada), Zebra Mussels are smaller, more square, and have a narrower body.

  • Scientific name: Dreissena polymorpha
  • Common name(s): Zebra Mussel

  • French name: Moule Zébrée

  • Regulatory status: Zebra mussels are listed under the federal Aquatic Invasive Species Regulations in Canada. It is prohibited to import Zebra Mussels into Canada. Efforts to prevent their entry into the country involve collaborations with the Canada Border Service Agency and provincial and territorial governments to intercept contaminated watercraft and aquarium products.

Zebra mussels

Zebra Mussel © Peter Taylor, some rights reserved (CC BY-NC)

Introduction and Spread

Native to the Black and Caspian Seas region of southeastern Europe, Zebra Mussels were first introduced to North America through ballast water discharged from ships in the late 1980s. They have since spread across eastern Canada and the United States, largely due to their ability to attach to watercraft and survive out of water for up to 18 days under humid conditions [1]. This trait allows them to be easily transported over land to new water bodies.

Distribution

Zebra Mussels have been found in several major water systems across North America, including Lake St. Clair, the Great Lakes, the St. Lawrence River, the Mississippi River watershed, Lake Winnipeg, Red River, Nelson River, and the Saint John (Wolastoq) River watershed. As of 2024, Fisheries and Oceans Canada have reported that zebra mussels have expanded into New Brunswick waters as far east as Mactaquac, near Fredericton, in the Wolastoq (Saint John) River.

Habitat

Zebra mussels thrive in freshwater environments and are incapable of surviving in marine conditions. They spread through natural water currents as larvae and can attach to any solid surface in the water [2]. Important dispersal mechanisms include attachment to watercraft and floating in ballast water, which necessitates the Clean, Drain, Dry protocol for water users moving between water bodies.

Identification

  • Larval Stage (Veligers): Microscopic and free-floating, they are difficult to detect without magnification. They move with water currents and are unable to swim on their own.

  • Adult Stage: Identified by their striped shells and small size, adults possess byssal threads near their shell’s opening which helps them to anchor to surfaces underwater.

Impacts

Zebra Mussels create significant ecological and socio-economic challenges. Ecologically, they disrupt food webs by outcpmpeting native mussels andfiltering the water of substrates. Clearer water increases the growth of aquatic vegetation and can cause toxic algal blooms [3]. They are particularly harmful to native mussel species, many of which are at risk of suffocation when Zebra Mussels attach to them. Economically, they cause extensive damage to water infrastructure and watercraft by clogging intake structures, leading to millions of dollars in damages annually in Canada.

Management Actions

Prevention and management of Zebra Mussel spread include:

  • Regulation: As a prohibited species, their import and transport are strictly regulated.

  • Surveillance and Monitoring: Environmental DNA (eDNA) sampling is used by provincial governments and federal agencies like Fisheries and Oceans Canada to assist with early detection. Public Education: Informing the public about the importance of cleaning, draining, and drying all watercraft and equipment.

  • Inspection and Decontamination: Provinces like Manitoba, Saskatchewan, and Alberta have implemented boat inspection and decontamination teams to prevent inland spread. It is important to follow the steps to Clean Drain Dry every time as larvae are invisible to the human eye and can survive approximately 18 days out of water.

What You Can Do:

Observations and Reporting:

The public is encouraged to report sightings of Zebra Mussels to help with early detection and management efforts. Reports can guide the implementation of rapid response strategies to contain and mitigate the spread of this invasive species.

CLEAN DRAIN DRY:

  • Inspect and clean plants, animals, and mud from watercraft, trailer, and gear (fishing gear, waders, boots, etc).
  • Drain all water from your watercraft, trailer, and gear (e.g. buckets, well, bilge, ballast etc.).
  • Dry all parts of your watercraft, trailer and gear completely between trips.

Additional Information

Resources:

1. Vanderbush, Brandon & Longhenry, Chris & Lucchesi, David & Barnes, Michael. (2021). A Review of Zebra Mussel Biology, Distribution, Aquatic Ecosystem Impacts, and Control with Specific Emphasis on South Dakota, USA. Open Journal of Ecology. 11. 163-182. 10.4236/oje.2021.112014.
2. Czerniawski, Robert, and Tomasz Krepski. “Does lake eutrophication support biological invasions in rivers? A study on Dreissena polymorpha (Bivalvia) in lake-river ecotones.” Ecology and evolution vol. 11,18 12686-12696. 13 Aug. 2021, doi:10.1002/ece3.8013
3. Czerniawski, Robert, and Józef Domagała. “Reduction of zooplankton communities in small lake outlets in relation to abiotic and biotic factors.” Oceanological and Hydrobiological Studies 42 (2013): 123-131.

Invasive Species Categories

Stop The Spread: Report Invasive Species

How to Prevent and Manage Invasive Species

The Impact of Invasive Species on Canada’s Ecosystems and Economy

Invasive Species Resources: Guides, Manuals, and Best Practices