Abstract
Atomic force microscopy (AFM), laboratory settlement assays and field tests were used to correlate cyprid footprint (FP) morphology with the behaviour of cyprids on different substrata. AFM imaging under laboratory conditions revealed more porous and larger FPs on glass exposing a CH3-surface than on aminosilane functionalised (NH2-) surfaces. The secreted FP volume was found to be similar on both substrata (2.1–2.6 μm3). Laboratory settlement assays and marine field tests were performed on three substrata, viz. untreated clean glass, NH2-glass, and CH3-glass. The results distinguished settlement preferences for NH2-glass and untreated glass over CH3-terminated surfaces, suggesting that cyprids favour settling on hydrophilic over hydrophobic surfaces. On combining observations from different length scales, it is speculated that the confined FP size on NH2-glass may induce a higher concentration of the settlement inducing protein complex. Settlement may be further facilitated by a stronger adherence of FP adhesives to the NH2-surface via Coulombic interactions.
Acknowledgements
The present research is supported by a Dutch Polymer Institute grant no. DPI–510 (to GJV). The authors thank Dr Wan Xin Sun from Veeco Asia for kindly providing instrumental support for AFM experiments. The authors also thank Dr Dominik Janczewski of IMRE for substantial support for the preparation of samples for field test and Mr Md Razali Bin Duriat from TMSI for the help in the preparation of panels for field test. They thank Xing Yi Ling from University of Twente for assistance in vapour-deposition of silane molecules on glass substrata and Ching Sing Lim of TMSI for assistance with field tests. The authors thank Prof Tony Clare and Dr Nick Aldred of the University of Newcastle for kindly providing cyprid larvae of B. amphitrite.