What Ontario is doing

To prevent these unwanted invaders from coming into the province, Ontario has regulated all species in the genus Salvinia (watermoss) as prohibited invasive species under the Invasive Species Act, 2015.

Learn more about the Invasive Species Act and regulations.

Background

Watermoss, also known by its genus name Salvinia, is a group of aquatic invasive ferns. They:

  • are free floating plants that thrive in nutrient rich waters
  • inhabit freshwater lakes, rivers, streams and ditches
  • prefer slow moving or stagnant water protected from wave action, where they are able to uptake more nutrients

While no longer permitted in Ontario, watermoss species are sometimes used in aquaria and backyard water gardens. Improper disposal of aquaria or water garden plants are the main pathways for its introduction to a new area.

Watermoss fronds can easily break off. If they are introduced to a new area, they can start a population.

Once established, watermoss species can spread rapidly through connected waterbodies, hitchhiking on uncleaned boats and equipment.

Range

Native distribution

Most Salvinia species are native to Central and South America and have been reported in more than 20 countries.

Salvinia natans, also known as floating fern, is native to Europe, Asia and Northern Africa.

Introduced range

  • Salvinia molesta (also known as giant salvinia) has populations in South Carolina, North Carolina, Virginia, New Jersey, Pennsylvania and California.
  • Salvinia minima, also known as water spangles or floating fern, have been reported in northeastern U.S. states including New York and Massachusetts.
  • Salvinia natans has been reported in the U.S. but no populations are currently known to be established. It is also established in Jamaica and Cuba.
  • To date there have been no documented reports of any Salvinia species in the wild in Ontario or anywhere in Canada.

Impacts of watermoss

Watermoss species can have a range of negative impacts in ecosystems they invade, including:

  • reducing biodiversity by creating dense mats on the water's surface, which blocks sunlight from reaching native species
  • reducing dissolved oxygen levels in water which can lead to fish kills
  • negatively impacting recreational activities such as boating and swimming
  • clogging water infrastructure, including hydro-electric power station intakes

How to identify watermoss

There are approximately 12 known species in the watermoss (Salvinia) genus. While the identification of each individual species will vary, they can be identified by common features including:

  • floating fronds with small round to oval leaves covered in tiny hairs, helping them stay afloat
  • bright green leaves which may appear lighter or darker depending on environmental conditions
  • rapid growth in favourable conditions, leading to the formation of dense mats on the water's surface

What you need to know

  • Learn how to identify watermoss species and how to prevent the introduction or spread of these plants into local waterways.
  • It is against the law to import, possess, deposit, release, transport, breed, grow, buy, sell, lease or trade any watermoss species in Ontario. 
  • Never release plants into the natural environment. This can unintentionally start an invasion that will negatively affect Ontario’s native species.
  • Never buy or grow any watermoss species to use in an aquarium, water garden, or for any other purpose. 
  • Always clean, drain and dry your watercraft if removing it and transporting it to another waterbody. 

As of January 1, 2022, boaters must open or remove drain plugs and other devices to allow water to drain. They must also take reasonable measures to remove plants, animals and algae from their watercraft, watercraft equipment and trailer before transporting it overland. Boaters must ensure watercraft, watercraft equipment and trailers do not have aquatic plants, animals, or algae attached to them before arriving at a launch site or placing the watercraft into any waterbody.

Reporting illegal activity

If you have any information about the illegal importation, distribution, or sale of any watermoss species, report it immediately to either:

If you see a watermoss species or another invasive species in the wild, do one of the following: