Behavioural bioassays for non-biocidal coatings

Abstract

Within hours, any undefended structure immersed in the marine environment will become fouled: a term known as biofouling. This phenomenon causes substantial economic losses and affects not only shipping vessels but also static structures. Although metal biocides added to coatings have proved very effective against biofouling, there were increasing concerns about the detrimental effects these were having on non-target species. The problem facing manufacturers of these coatings is the lack of available testing methods for non-biocidal antifouling coatings. This thesis aims to develop a framework for a suite of behavioural bioassays to investigate the efficiency of non-biocidal coatings. The research represents methodological investigations coupled to pilot studies. Three fouling species were investigated, Spirorbis borealis, Balanus amphitrite, and Balanus improvisus. All three species showed significant differences in behaviour on nonbiocidal coatings supplied by Akzo Nobel and these behaviours could be used to discriminate between coatings. Immersion trials were carried out in Sweden, Singapore and the UK, in order to ascertain whether behavioural parameters of the larvae in the laboratory could be used to predict fouling observed in the field. All three species demonstrated that aspects of their behaviour could be used to predict fouling at least at one location, with both Spirorbis borealis and Balanus amphitrite displaying behaviour that could be used to predict fouling in all three sites. The research showed that the behavioural bioassays have the potential to be developed into an acceptable commercial screening test. From the conclusions a final protocol for filming, digitising and analysing larval behaviour, in order to predict field fouling is presented. Development of this protocol could lead to a rapid commercial screening test for non-biocidal antifouling coatings.