Correlative assays of barnacle cyprid behaviour for the laboratory evaluation of antifouling coatings: a study of surface energy components

Abstract

Laboratory evaluation of antifouling coatings is underpinned by settlement studies with specific fouling organisms. Established methods provide insight into the likelihood of failure of a particular coating system, but can neglect the process of surface selection that often precedes attachment. The present approach for quantifying the exploratory behaviour of barnacle cypris larvae suggested that inspection behaviour can be a rapid and predictive proxy for settlement. Two series of xerogels with comparable total surface energy, but different dispersive and polar components, were evaluated. Settlement assays with three-day-old cyprids of Balanus improvisus demonstrated that while attachment was not linked directly to dispersive free energy, the composition of the xerogel was nevertheless significant. Behavioural analysis provided insight into the mechanism of surface rejection. In the case of a 50:50 PH/TEOS (phenyltriethoxysilane-based) xerogel vs a 50:50 TFP/TEOS (3,3,3-trifluoropropyltrimethoxysilane-based) xerogel, wide-searching behaviour was absent on the former.

Keywords:

• Barnacle
• antifouling
• settlement behaviour
• behavioural analysis
• cyprid
• xerogel

Acknowledgements

All of the authors are grateful to Dr Eric Holm of the Naval Surface Warfare Centre for his helpful comments on the experiments and draft manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors extend their gratitude to the Office of Naval Research (ONR) for funding support to develop their larval tracking system [N00014-13-1-0633, N00014-16-1-2988 to ASC; N00014-13-1-0634, N00014-16-1-3125 to ASC & NA], and to the European Commission [FP7 SEAFRONT project] (ASC). MRD would also like to thank the ONR for funding support [N0014-16-1-3065, N0014-16-1-2143].