Field-based Behavioural Bioassays for Testing the Efficacy of Antifouling Coatings

Improving non-toxic coatings using immersion trials is time consuming and requires more rigorous data analysis than is necessary for toxic coatings. The aim of this study was to determine if the exploratory behaviour of barnacle cyprids on coatings deployed in the field can be used as a bioassay for coating efficacy. A standard tin-based coating, and a silicone and unknown non-toxic coatings were videoed remotely underwater using a high resolution camera. Exploratory behaviours of the coatings by cyprids were digitised. There was a significant difference in larval behaviour between coatings (MANOVA, p <0.001 ). Canonical discriminant analysis clearly separated the three coatings and enabled 100% prediction of group membership. Thus the behaviour of exploring cyprids can be used to discriminate between the coatings. This study has demonstrated how a simple field-based bioassay could be suitable for the testing of antifouling coatings and may therefore offer some scope for rapidly pre-screening coatings prior to full-scale immersion trials. However, several disadvantages with the bioassay are noted, including variable illumination in the field, the high cost of the equipment used, the long time required to manually analyse recorded video, and the need for a predictable larval supply.

Keywords:

• Coating
• Bioassay
• Cyprid
• Semibalanus
• Immersion Trials
• Barnacle