Mini-review: Impact and dynamics of surface fouling by solitary and compound ascidians

Abstract

Globally, ascidians are a significant contributor to benthic marine fouling communities, but have remained poorly studied in this context. In some cases, such as in shellfish and finfish aquaculture, ascidians are the most problematic of all fouling organisms. The disproportionate impact of ascidian fouling in some specific geographic locations has been related directly to anthropogenic translocation of these organisms around the globe. In the case of ascidians, therefore, the economic issue of biofouling and the ecological ramifications of invasion are inextricably linked. This mini-review briefly discusses the introduction of non-native ascidians to areas where they have subsequently proven to be a significant fouling pest. The elements of ascidian reproductive ecology that support their aggressive fouling character are discussed and the scant information pertaining to their adhesion and adhesives is presented. Finally, strategies for mitigating ascidian fouling are examined. It is suggested that sufficient working knowledge currently exists to support the inclusion of one or more common ascidian species as ‘standard’ test organisms used for evaluation of novel fouling-resistant surfaces.

Keywords:

• ascidian
• tunicate
• settlement
• adhesion
• biofouling
• fouling

Acknowledgements

The authors gratefully acknowledge three anonymous peer reviewers and Dr David Williams (Akzo Nobel, International Paint Ltd.) for their assistance and contributions during the drafting of this manuscript. They also thank Dr Cory Bishop for providing images for use in Figure 2. Nick Aldred and Tony Clare acknowledge funding support from the Office of Naval Research [Grants N00014-08-1-1240, N00014-13-1-0633 and N00014-13-1-0634 to A.S. Clare] and Nick Aldred was granted a James Chair visiting professorship at St Francis Xavier University, during which valuable experience with these organisms was gained.