Aquatic Invasive Species (AIS) Outreach Project
Aquatic Invasive Species (AIS) Background
The presence of AIS is one of the most pervasive and potentially irreversible impacts on marine ecosystems. The World Conservation Union (IUCN) rates AIS as one of the four greatest threats to the world’s oceans, along with land-based pollution, over-exploitation of resources, and destruction of habitat. AIS in BC’s marine environment, such as invasive tunicates, or the European green crab may pose significant ecological and economic risks to the shellfish farming industry and other marine stakeholders. On Canada’s East coast, invasive tunicates have resulted in significant grow-out, harvesting and processing challenges for the mussel farming industry.
Therefore, this interpretive website was produced as a pro-active measure, to help marine stakeholders identify AIS so that further colonization or spread may be controlled. The species highlighted on this site should not be confused with the various native tunicates or crab species.
Why Look for Tunicates?
Tunicates are known as fouling organisms. This means they grow on hard substrates such as rock, boulders and gravel as well as artificial substrates such as boat hulls, docks, and aquaculture gear. Tunicates can out compete and suffocate filter feeding bivalves such as mussels and oysters.
What is a Tunicate?
A tunicate is a filter-feeding invertebrate. Tunicates draw water in through an incurrent siphon, filter food from the water passing through their pharynx, and expel the filtered water and waste products out an excurrent siphon. Tunicates can be solitary (Figure 1) or colonial (Figure 2) where there are multiple smaller versions, called zooids, embedded within a common tinuc. Colonial tunicates can regrow from small fragments of the colony.
Figure 1. Solitary Tunicate
Figure 2. Colonial Tunicate
