Using Disruptive Coloration and Ultraviolet Light to Prevent Barnacle Settlement
Richard, Kailey Nicole
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Biofouling or the accumulation of unwanted micro and macro organisms is problematic for the shipping industry. Barnacles are one of the most abundant fouling organisms and their settlement on ship hulls can result in costly damage. Several methods have been developed to prevent the formation of biofouling, including antifouling coatings and mechanical techniques, but the search for more effective and environmentally friendly solutions is still ongoing. This thesis investigated two methods aimed at barnacle prevention: color patterning and the application of ultraviolet light. The first method utilized disruptive coloration, a common mechanism observed in nature by terrestrial organisms (i.e. butterflies) and marine organisms (i.e. cuttlefish), to distort the outline of the organism hindering it from detection. Two patterns (dots and stripes) and two-color patterns (white/red and yellow/red) were selected. In addition, three different sizes of these patterns were created based on the average size range of a barnacle cyprid: 1mm width by 1.5 mm spacing, 0.5 mm width by 0.75 mm spacing, and 0.25 mm width by 0.35 mm spacing. Testing over a four-month period, determined barnacle settlement was significantly different among patterns for months 1 and 3. However due to low settlement, the differences were not consistent throughout the study, and therefore disruptive coloration and pattern types could not definitely be identified as an antifouling mechanism. The second method used ultraviolet-C light (UVC) in synergy with surfaces of varying colors (red and white) and reflective properties (stainless steel and polycarbonate) to prevent barnacle settlement. Two small studies were conducted using two frequencies (one minute a day and one minute every six hours) each for a one-month period. In addition to investigating how the different surfaces worked with UVC, the indirect effect of stainless steel on polycarbonate was also tested. Barnacle settlement was not significant among UVC exposure to color panels, surface type, or by the indirect effects of stainless steel on polycarbonate. While both of the novel methods tested: disruptive color and UVC, did not have a consistent effect on barnacle settlement, some impact on other members of the biofouling community were observed. For example, tubeworm settlement was found to be greater on red surfaces compared to white surfaces and settled regularly on stainless steel panels over polycarbonate panels. Future work should investigate the impacts of both disruptive coloration and the application of UVC to target other members of the biofouling community. In addition, both of these techniques may be more successful when used in combination with additional antifouling methods.