Commercial shellfish farming is increasing in Brazil to provide for the growing local and international markets. Shellfish (mussel and oyster) production in Brazil is greatest in the state of Santa Catarina where three sea ports with national and international commerce are sources of non-indigenous species (NIS) that have the potential to find suitable habitat in the shellfish farms. Here we describe the tunicate community associated with shellfish farms during the past 10 years. Survey results

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... identified 17 species of which only one was native. Two were clearly introduced. Of the 14 species classified as cryptogenic, 10 were probably introduced. Tunicates become very abundant in farms and as a consequence farms require periodic cleaning of the shells as well as associated equipment. Styela plicata and Didemnum perlucidum are the most abundant and may become a threat to natural communities, but they are currently not found on natural substrates. Ciona intestinalis and Styela clava were not found in shellfish farms, even though C. intestinalis, at least, has been introduced many times in Brazil. We recommend that a public awareness program be developed to prevent colonization by C. intestinalis in the bivalve farms. Additionally, we emphasize that the diversity of possibly introduced species also requires close monitoring for rapidly expanding populations, since a diversity of life cycles and biological requirements also increases the probability of the appearance of a new pest.