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Vase Tunicate

Ciona intestinalis

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If you think you have found an aquatic invasive species:

  1. do not return the species to the water
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    • the exact location (GPS coordinates)
    • the observation date
    • identifying features
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Vase tunicate. Also called: Sea vase tunicate

Vase tunicate. Also called: Sea vase tunicate

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The Vase Tunicate is an invasive solitary tunicate believed to have originated in the Northeast Atlantic.

Origin and distribution

The earliest record of Vase Tunicate in North America was in the eastern United States in 1850 and on the Canadian east coast (New Brunswick) in 1852. It was uncommon in the region until 1997, when large populations of the species were discovered on the southwest coast of Nova Scotia. The species was first recorded in Prince Edward Island in 2004. The species is now found in:

In Newfoundland, Vase Tunicate was first identified on September 19, 2012, during a DFO wharf and breakwater dive survey in Burin, Placentia Bay. This is the first record of vase tunicate in Newfoundland waters. Follow-up surveys in October and November 2012 discovered Vase Tunicate was also present in Little Bay and Marystown. The greatest abundance was found in Little Bay on:

Smaller numbers were found in Burin and Marystown on wharf structures. The species has not been found in any Newfoundland aquaculture farms to date.

Map showing the Canadian Maritime Provinces: Nova Scotia (N.S.), New Brunswick (N.B.), Prince Edward Island (P.E.I.). Their surrounding coastal waters are divided into subregions, which are outlined in black. Areas that have green shading indicate that Vase Tunicate has been observed in subregions: 1: Bay of Fundy (N.S.), 2: Southwest (N.S.), 3: Eastern Shore (N.S.), 4: Cape Breton (N.S.), 5: Northumberland Strait (N.S.), 6. Bay of Fundy (N.B.), 7: Chaleur Bay (N.B.), 10: Northumberland Strait (P.E.I.), 11: Gulf of St. Lawrence (P.E.I.).

Observed distribution of Vase Tunicate in subregions of Canada's Maritime provinces.

Note: Observation within a subregion does not mean the species is found throughout it. Lack of observation within a subregion does not mean the species is absent from that subregion. It means that it has not been observed there.

Map showing the distribution of Vase Tunicate in Gulf region waters of: northeastern Nova Scotia (N.S.), eastern and northern New Brunswick (N.B.), Prince Edward Island (P.E.I.). A red dot indicates that this species has been observed in that location.

Vase Tunicate distribution in Gulf region

Click image to enlarge

Vase Tunicate Distribution in Newfoundland Waters

Vase Tunicate Distribution in Newfoundland Waters

Click image to enlarge.

Distribution Location and Bay
  • Burin
  • Little Bay
  • Marystown

Identifying features

Similar species (native)

Sea Potatoes (Boltenia ovifera), Sea Grapes (species in the genus Molgula) and Sea Peaches (Halocynthia pyriformis) are native solitary tunicate species that may be confused for the Vase Tunicate. However, these native solitary tunicates usually grow alone or in small groups (not found in dense aggregations) and differ in their shape and texture from the Vase Tunicate:

Habitat

Temperature and salinity play a major role in the growth and reproduction of vase tunicate. In temperate or shallow regions, Vase Tunicates may live 12 to 18 months and produce 2 generations per year; however they may live 2 to 3 years and reproduce 1 year or less in deeper, colder areas.

Ecological and economic impacts

Vase tunicate

Vase tunicate

Since the Vase Tunicate is a filter feeding animal, it is a natural competitor for other filter feeders (including mussels and other commercial bivalves). Aquaculture farms in the Maritimes (particularly Nova Scotia and Prince Edward Island) have reported:

The Vase Tunicate is mostly composed of water, and in dense aggregations can carry substantial weight. This added weight may lead to increased maintenance cost to boaters, as well as decreased boat speed and maneuverability.

Mode of arrival

The Vase Tunicate likely reached Canadian waters attached to the hulls of ships.

Mode of dissemination

Vase Tunicate regional dispersion is likely dues to hull fouling of slow-moving vessels such as floating barges, small fishing or recreational water craft within many coastal areas.

Government action

Fisheries and Oceans Canada is monitoring the distribution of invasive biofouling species (that is, aquatic species that live attached to hard surfaces) on the Atlantic and Pacific Coasts to detect new invasions and track the spread of Vase Tunicate. Research is ongoing to learn about the biology of this species in the Newfoundland environment and to develop mitigation methods and communications strategies to control and prevent its spread throughout the province.

Controlling abundance

Vase Tunicate is listed as the most problematic invasive species to mussel aquaculture in the Maritime Provinces, and therefore every effort must be made to prevent the spread of the species to eastern mussel aquaculture farms.

Tunicates can be easily spread through movement of gear, shellfish, and commercial and recreational boats. To control the spread of vase tunicate, boat hulls and gear should be visually inspected and cleaned regularly by letting air dry for at least 48 hours. Care should be taken that plant and animal material and water is disposed of on land and no materials go back into the water. Antifouling paints are effective in preventing settlement of vase tunicate and should be applied regularly. Every effort should be made to remove populations from wharves and surrounding structures.

Surveys and monitoring for vase tunicate is an effective tool in early detection. Early detection of recently established populations may provide an opportunity to control, contain, or ideally eradicate new populations before they spread.

For further information

References

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