Effects of environmental and surface factors on settlement and adhesion of the barnacle Balanus amphrite

PhD ThesisBiofouling is a substantial problem for the maritime industry. Organisms growing on underwater surfaces increase drag on ships’ hulls and damage coastal machinery. Billions of dollars are spent annually on mitigating fouling. The tropical barnacle (Balanus amphitrite) is a major fouling species. This thesis investigates the effects of some of the major environmental controls for this benthic species, (surface chemistry, temperature and food availability), on the adhesion and adhesives of two of its life cycle stages, the settlement-stage cypris larva (the final larval stage of barnacles) and the adult

Competence and discrimination during cyprid settlement in Amphibalanus amphitrite

Amphibalanus (=Balanus) amphitrite is a tropical/sub-tropical barnacle species which is naturally exposed to sea temperatures of 16-27 degrees C throughout its larval development. An established technique widely employed by investigators of A. amphitrite settlement involves the storage of cyprids at 4-6 degrees C prior to their use in bioassays. Our study focuses on the effects on ageing temperature on settlement and discrimination of A. amphitrite larvae. Using cyprids aged at 2 temperatures, 6 and 23 degrees C, we confirmed the general trend in the literature that young d0 cyprids of this species do not appear competent to settle. Performing cyprid settlement assays at 20, 25 or 28 degrees C, we observed that the proportion of settled cyprids when incubated at 28 degrees C was greater than that of cyprid incubated at 25 degrees C and 20 degrees C. Settlement rates of cyprids aged at 6 degrees C and 23 C increased relative to age from d1 to d10 irrespective of temperature. Cyprids lost the ability to undergo attachment and metamorphosis at d14 or d15 when aged at 6 degrees C or 23 degrees C respectively. In the choice assays executed in this study, cyprids generally chose to settle on adult extract-treated areas. But localised settlement on adult extract-treated areas decreased with time. Choice settlement assays at set age intervals during the cypris larval stage showed that cyprids were able to discriminate between con- and allospecific adult extracts. The duration and the temperature of cyprids storage influenced selectivity. (C) 2012 Elsevier Ltd. All rights reserved

The effects of a serine protease, Alcalase®, on the adhesives of barnacle cyprids (Balanus amphitrite)

Barnacles are a persistent fouling problem in the marine environment, although their effects (eg reduced fuel efficiency, increased corrosion) can be reduced through the application of antifouling or fouling-release coatings to marine structures. However, the developments of fouling-resistant coatings that are cost-effective and that are not deleterious to the marine environment are continually being sought. The incorporation of proteolytic enzymes into coatings has been suggested as one potential option. In this study, the efficacy of a commercially available serine endopeptidase, Alcalase® as an antifoulant is assessed and its mode of action on barnacle cypris larvae investigated. In situ atomic force microscopy (AFM) of barnacle cyprid adhesives during exposure to Alcalase supported the hypothesis that Alcalase reduces the effectiveness of the cyprid adhesives, rather than deterring the organisms from settling. Quantitative behavioural tracking of cyprids, using Ethovision 3.1, further supported this observation. Alcalase removed cyprid 'footprint' deposits from glass surfaces within 26 min, but cyprid permanent cement became resistant to attack by Alcalase within 15 h of expression, acquiring a crystalline appearance in its cured state. It is concluded that Alcalase has antifouling potential on the basis of its effects on cyprid footprints, un-cured permanent cement and its non-toxic mode of action, providing that it can be successfully incorporated into a coating

Real-Time Monitoring of Tetraselmis suecica in A Saline Environment as Means of Early Water Pollution Detection

Biological water pollution, including organic pollutants and their possible transportation, via biofouling and ballast water, has the potential to cause severe economic and health impacts on society and environment. Current water pollution monitoring methods are limited by transportation of samples to the laboratory for analysis, which could take weeks. There is an urgent need for a water quality monitoring technique that generates real-time data. The study aims to assess the feasibility of three sensing techniques to detect and monitor the concentrations of the model species Tetraselmis suecica in real-time using eleven samples for each method. Results showed UV-Vis spectrophotometer detected increasing concentration of Tetraselmis suecica with R2 = 0.9627 and R2 = 0.9672, at 450 nm and 650 nm wavelengths, respectively. Secondly, low-frequency capacitance measurements showed a linear relationship with increasing concentration of Tetraselmis suecica at 150 Hz (R2 = 0.8463) and 180 Hz (R2 = 0.8391). Finally, a planar electromagnetic wave sensor measuring the reflected power S11 amplitude detected increasing cell density at 4 GHz (R2 = 0.8019)

Poly(ethylene glycol)-Containing Hydrogel Surfaces for Antifouling Applications in Marine and Freshwater Environments

This work describes the fabrication, characterization, and biological evaluation of a thin protein-resistant poly(ethylene glycol) (PEG)-based hydrogel coating for antifouling applications. The coating was fabricated by free-radical polymerization on silanized glass and silicon and on polystyrene-covered silicon and gold. The physicochemical properties of the coating were characterized by infrared spectroscopy, ellipsometry, and contact angle measurements. In particular, the chemical stability of the coating in artificial seawater was evaluated over a six-month period. These measurements indicated that the degradation process was slow under the test conditions chosen, with the coating thickness and composition changing only marginally over the period. The settlement behavior of a broad and diverse group of marine and freshwater fouling organisms was evaluated. The tested organisms were barnacle larvae (Balanus amphitrite), algal zoospores (Ulva linza), diatoms (Navicula perminuta), and three bacteria species (Cobetia marina, Marinobacter hydrocarbonoclasticus, and Pseudomonas fluorescens). The biological results showed that the hydrogel coating exhibited excellent antifouling properties with respect to settlement and removal. © 2008 American Chemical Society