Aquatic species

Zebra mussels (dreissena polymorpha) are a small invasive freshwater mussel from southwestern Europe (specifically the Black and Caspian Seas) that first arrived in the Great Lakes in the 1980s. Since then, they have been spreading through eastern Canada and the United States impacting ecosystems, recreational activities and infrastructure.

Zebra mussels are filter feeders that will attach themselves to any solid surfaces touching infested waterways, like boats, docks, rocks, plants and native mussels. The females can produce up to one million eggs per breeding season, and the larvae can float in the water column for up to a month before attaching to available surfaces, colonizing in densities of up to 700,00 individual mussels per m². 

The presence of zebra mussels can negatively impact freshwater ecosystems by: 

• filtering water to the point where important food sources like plankton are depleted, which alters food webs (over-filtering also creates clear water allowing sunlight to penetrate deeper, which can increase growth of invasive aquatic plants like Eurasian watermilfoil)
• increasing toxic algae blooms, pathogenic bacteria and avian botulism, which impacts fish and wildlife
• altering spawning areas by changing the materials on the bottom of waterways, impacting fish egg survival

Since they are capable of heavily colonizing on various surfaces, they can also negatively impact recreational activities and vital infrastructure. Due to their razor-sharp shell, recreational users are at a risk of cutting their feet while walking on beaches or swimming in water infested by zebra mussels. These invasive mussels are also responsible for clogging intake structures used by water treatment facilities and power plants. The management of zebra mussels can be costly for local government agencies. Between 2017 and 2019, municipalities in Ontario reported spending $4.5 million annually on the control, prevention and detection of these mussels.

Larval zebra mussels, called veligers, are difficult to identify as they are too small to see with the naked eye. They are unable to swim on their own so they are free-floating, moving with the water currents.

Adult zebra mussels can be identified by their:

• triangular shape, often with dark and/or light bands on their shells
• small size (ranging from two to four centimeters long)
• tuft of fine threads, called byssal threads, near the opening of the bottom of the shell, which they use to firmly attach to underwater surfaces

Clean, drain and dry any recreational equipment (boats, canoes, kayaks, fishing gear, etc.) before entering a new body of water.

Learn how to identify zebra mussels using the identification above and/or by visiting NBISC’s website.

Report any sightings immediately to:

New Brunswick Invasive Species Council  
E-mail: [email protected]
Website: www.nbinvasives.ca/report-an-invasive-species

Department of Fisheries and Oceans
E-mail: [email protected]
Phone: 1-866-759-6600

Department of Natural Resources
Email: [email protected]
Phone: 506-453-3826

Include the following information:

• the exact location of the sighting (GPS coordinates) and date
• identifying features and photos of the mussel(s)

While some water-milfoil species are native to New Brunswick, Eurasian watermilfoil (myriophyllum spicatum) are an invasive species present in the Madawaska River and throughout the Saint John River. This submersed aquatic plant creates dense mats that interfere with recreational activity. It out-competes native plants, which negatively impacts our fish and wildlife. This invasive plant can spread when fragments cling to boats, motors and trailers and are moved to new areas.

Eurasian watermilfoil have:

• feather-like leaves arranged in whorls of three to six around the stem (four leaves are the most common) 
• whorls that are openly spaced (one centimeter or more) on long spaghetti-like stems 
• an average of 12 to 24 leaflet pairs per leaf 
• a plant tip that’s reddish in colour and small reddish flowers appear above the water surface in mid-summer

Do not pass through mats of vegetation and follow the guidelines below when moving from one body of water to another. Every time you move between water bodies, there is a risk of transporting aquatic invasive species. Please do the following:

• inspect and remove all visible aquatic plants, animals and mud from canoes, kayaks, jet skis, boats, motors, trailers, etc. 
• drain all the water from your boat, including the live well, bilge and motor
• wash watercraft with high-pressure or hot water or dry for five days
• check, clean and dry all personal gear, including waders, fishing lines and lures 
• dispose of unused bait responsibly
• never release plants, fish or other animals into a body of water unless they came out of that water

New Brunswick has one native crayfish, the Appalachian brook crayfish (cambarus bartoni), and two non-native introductions: the spinycheek crayfish (orconectes limosus) and the virile crayfish (o. virilis). Both non-native species are expanding their range in New Brunswick.

• adult non-native crayfish are up to 55 mm in carapace length (the native crayfish rarely exceeds 30 mm)
• the rostrum (the pointed projection between the eyes) is long when compared to that of the native crayfish
• one species has prominent spines on the sides of the head while another species has paired brownish, reddish, or greenish spots on the top of the tail section (neither of these features is present in the native species)

• remove any visible material and eliminate water from equipment before transporting (crayfish can survive for extended periods out of water, and newly hatched crayfish are barely visible to the eye)
• never release crayfish into a body of water unless they came from that water

Curly-leaf pondweed is an aquatic plant that can grow to form dense mats. These mats can alter and degrade the habitat of native plants, fish and wildlife and interfere with water-based recreation on lakes. Dying plants can accumulate on shorelines and contribute to algal blooms.

• curly-leaf pondweed is generally the first pondweed to come up in spring and to die back in summer
• all leaves are underwater
• leaf edges are serrated and wavy, like lasagna noodles
• generally grows in water 1-3m deep
• prefers shady, disturbed, dirty water

• remove all vegetation from your equipment before moving from one location to another
• never put wild or ornamental aquatic plants into natural water bodies

Didymo, or “rock snot,” is a freshwater alga that can form a thick mat that covers the stream bottom. This can impact native fish, plant and invertebrate communities. Didymo is not a threat to human health but can affect the enjoyment of recreational activities. It only takes a single cell to start a new colony.

• didymo looks slimy but feels like wet cotton wool
• it's beige/brown but never green
• it does not smell
• it's firmly attached and does not fall apart when rubbed
• dry didymo looks like toilet paper
• young colonies look like raised pimples on rocks

Check, clean and dry all equipment before moving from one location to another, even on the same water body. Follow established cleaning protocols.

Yellow floating heart is a water lily-like plant that spreads aggressively. These mats can displace native plants and animals, disrupt food webs, lower oxygen levels in the water, and interfere with water-based recreation.

• flowers have five petals arranged like a star
• two to five yellow flowers per stalk
• heart-shaped floating leaves notched almost to the centre, with slightly wavy margins and purplish undersides
• leaves measure three to 10 cm in diameter

• remove all vegetation from your equipment before moving from one location to another
• never put wild or ornamental aquatic plants into natural water bodies