Summary 1.Extensive research has been carried out on the biological, physical and chemical characteristics of surfaces that promote, or prevent, marine fouling. The texture of the substratum is probably the most important factor affecting settlement of the Acorn Barnacle Semibalanus balanoides in the field. The aim of this study was to examine the relationship between fractal and Euclidean descriptions of substratum surface complexity and settlement of the Acorn Barnacle. 2. Replicate settlement panels with smooth, fine, medium and coarse surfaces were manufactured using a precise and accurate technique. Two-dimensional profiles were measured using a laser profilometer, and two surface complexity indices, potential settling sites (PSS) and the Minkowski fractal dimension (MFD) were calculated. PSS is a Euclidean measure of the surface complexity taking into account the body size and settlement behaviour of the barnacle larvae, whereas MFD is a fractal dimension related to the complexity of the surface at a variety of scales. 3. In a field experiment, settlement density of S. balanoides was positively related to both PSS and MFD. To break the correlation between PSS and MFD, surfaces were modified by sandblasting with either 64-125-µm or 250-500-µm grains. This decreased MFD but did not affect PSS. 4. A further field experiment found that this erosion using small-scale sand particles had no effect on settlement of the barnacle. It was concluded that S. balanoides larvae were responding to characteristics of the surface related to PSS and not MFD. 5. Although a correlation was found between species abundance and the fractal complexity of its habitat, further experimentation showed that there was no causality in this relationship. Many surveys, with no experimentation, of aquatic and terrestrial communities have shown relationships between organisms and their habitat and assumed causality; however, care must be taken in interpretation of such studies. Jacobi & Langevin 1996;Wieczorek & Todd 1998). The most common fouling marine invertebrates are barnacles, which are ecologically and economically important and consequently they have been extensively studied (see, for example, Stubbings 1975;Crisp 1984;Southward 1987). The thoracian barnacles are characterized by the Acorn Barnacle Semibalanus balanoides L. The adult barnacle is sessile and dispersion and colonization of new sites is achieved by a planktonic larva. The process of moving from the final stage planktonic larva (cyprid) to the settled adult barnacle requires careful selection of the settlement site if metamorphosis is to be successful and fitness of the adult is to be maximized (e.g. Young 1987;Hoffman 1988;Raimondi 1988, Raimondi 1990Walters & Wethey 1991;Pineda 1994). Many barnacle species have been shown to be highly selective in their choice of the settlement site, even in a high energy littoral zone, and parameters such as colour (Kon-ya & Miki 1994) Much work has been carried out on the effect of surface roughness on the settlement of barnacles. ...
We describe the calibration of a technique allowing quantitative measurements of industrial coatings with thicknesses as small as 10-20 nm. Wax films doped with fluorescent rhodamine dye have been deposited by an electrospray method onto an optically flat surface of aluminium-coated glass. The films were of 220-450 nm peak thickness, which we measured with an optical profilometer using laser triangulation. Possession of a set of films allowing an absolute calibration of the fluorescence intensity versus thickness to be achieved for application in trials of the fluorescence method for measuring coating thicknesses of 10-20 nm under industrial process conditions.
A highly precise technique for manufacturing tiles with complex naturalistic three-dimensional surfaces for macrofaunal settlement studies is described. The tiles are cast in filled polyester resin from polyvinylsiloxane impressions of model surfaces. Comparison of settlement of barnacle cypris larvae (Semibalanus balanoides) between one week and one year old tiles showed that there was no toxic effect of the resin on settlement or recruitment. Analysis of the surfaces using a laser profilometer demonstrated that the mean difference between two tiles cast from the same mould was 1.9 µm. The tiles are very strong, stable in both freshwater and seawater, can be made in most colours and can be used to replicate biotic and abiotic substrata. They have been tested in a variety of settlement studies at various sites around the world.
Personnel will wear protective clothing andgloves at all timeswhile handling beryllium components of thereflector system. Respirators will be worn, and vacuum cleaners used, while filing or cutting beryllium parts. Radiation measuring devices will be worn by all personnel working in the radiation area. The appropriate safety organization will be notified prior to the commencement of work. No smoking will be permitted in the Restricted Area. All steel parts used in the assemblies will require a protective film. Completed sector assemblies and drive shaft assemblies will be firmly secured in their respective shipping containers and stored at LASL while waiting shipment to NRDS. Reflector assembly work sheets, containing serial numbers, must be filled out during the assembly. See sample sheets, pages 28 and 29. The Reflector System Parts List showing Description, Part No., Quantity for Sub-Assembly and Quantity for Reactor Assembly Is shown on pages 30, 31 and 32. A Tooling List for the Reflector Sector Assembly Is shown on page 32. All changes to procedures and/or parts must be reported on specified forms. Sample change forms (pages 33 and 34) are Included.
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