Golden Star Tunicate


Golden Star Tunicate, or Botryllus schlosseri, is a colonial tunicate which forms flat colonies and may vary from orange, yellow, green, or violet in colour. Zooids (individuals) are about 1 to 2 mm in width and grouped such that they form a star or flower shaped pattern 5 to 10 mm in diameter. They grow on a variety of man-made substrates (docks, boat hulls, buoys, ropes, etc.) and natural hard substrates in the shallow subitdal zone, mainly in protected areas. This tunicate can withstand estuarine environments with low salinities (down to 15 ppt).

Eggs are fertilized within the matrix of the colony and larvee are free-swimming for up to 24 hours. Like other colonial tunicate species golden star tunicate can produce new colonies from fragments.

(Photo credit : D. Mouland, DFA)

Means of introduction

Since the larval period of Golden Star Tunicate is short it is not likely spread through ballast water and is thought to be spread mainly through hill fouling.

Managment of the species

Fish and shellfish harvesters should avoid transferring harvested shellfish and fishing gear to other areas. Gear should be thoroughly dried before transfer. Boat hulls should be inspected and, if necessary, manually cleaned. Any organisms removed from the boat hulls or gear should be disposed of on land. If pressure washing is necessary to remove the colonial tunicates off equipment only do so on land (not on the water) and make sure the out-flow does not go into the sea, as colonies can re-grow from small fragments. Report sightings by using the contact information on the main AIS page.

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