Massachusetts, Hawaii and Florida) using static immer- .... collected at Ford Island and at the Florida Institute of Technology (FIT) exposure platform in the.
and Spatial Variations in Macrofouling Macrofouling of Temporal and of Silicone Fouling-release Coatings WOOD 1,1,*, *, KATHRYN TRUBY!, TRUBY1, JUDITH STEIN!, STEIN1, CHRISTINA DARKANGELO WOOD 33 4 2 4 DEBORAH WIEBE ,, ERIC HOLM , DEAN WENDTi, WENDT , CELIA SMITH ,, CHRISTOPHER CHRISTOPHER KAVANAGH5s, JEAN MONTEMARAN0 MONTEMARANO 33, GEOFF SWAINS SWAIN5 and ANNE MEYER6 1 ICE USA; GE Corporate Corporate Research Research and and Development, K1-4A54, One One Research Research Circle, Circle, Niskayuna, Niskayuna, NY NY 12309, USA; 2 2Bridger USA; Bridger Scientific, Bourne, MA 02532, USA; USA; 33NSWCCD, NSWCCD, Bethesda, MD 20084, USA; 4 4University Institute of Technology, Technology, Melbourne, FL 32901, USA; USA; University of Hawaii, Honolulu, Honolulu, HI 96813, USA; USA; 55Florida Florida Institute 6University NY 14214, USA 'University at Buffalo, Buffalo, NY
Nontoxic, low low surface free energy silicone coatings having reduced biofouling adhesion strength have been developed as as an alternative to to antifouling paints. macrofouling to to adhere; how howSilicone coatings permit macrofouling ever, fouling can be removed easily by water pressure or One of the the current methods used to light scrubbing. One the performance of non-toxic silicone fouling foulingevaluate the release coatings relies heavily on fouling coverage. The organismal community structure as as well as as total can affect affect the the ease of fouling removal from from coverage can these coatings. This paper explores fouling coverage fouland organismal adhesion over time. Long-term foul ing coverage data were collected at four sites (in (in immerMassachusetts, Hawaii and Florida) using static immer and oil-amended sion panels coated with silicone and differences in fouling cover coversilicone systems. Inter-site differences and community structure were observed for each age and coating. Intra-site Intra-site variation variation and and temporal temporal change change in coating. coverage of of fouling fouling was minimal, regardless of of coating coating coverage was minimal, formulation. The The extent extent of of coverage coverage was affected by the formulation. was affected by the duration of of immersion immersion and and the the local local environmental environmental duration conditions; these these factors factors may may also also have an impact impact on on the the have an conditions; foul-release capability capability of of the the silicone silicone coatings. coatings. Organ Organfoul-release ismal adhesion adhesion data data was collected in in Hawaii Hawaii and ismal was collected and Florida. These These adhesion adhesion measurements as aa Florida. measurements were were used used as tool to to discriminate discriminate and and rank fouling release coatings. rank fouling release coatings. tool
Keywords: fouling Keywords: foulingrelease; release;coatings; coatings;silicone; silicone;coverage; coverage; barnacle adhesion; tubeworrn tubeworm adhesion; oyster adhesion
INTRODUCTION environBiofouling is ubiquitous in the aquatic environ ment. Fouling on the hulls of marine vessels has been shown to reduce maximum speed and in increase propulsive fuel consumption (Haslbeck & & Bohlander, 1997). Traditional antifouling paints containing toxic triorganotin compounds or effective in controlling cupric oxide are highly effective the fouling (Bleile & & Rodgers, 1989). 1989). Due to envi environmental concerns, however, the application of of on triorganotin-based paints has been prohibited On smaller vessels ( 50 0
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structure. These seasonal changes reflected the fouling season common in temperate regions. eviThe cyclical pattern in coverage was more evi dent on RTVll RTV11® than on RTV11® + 10% SF1154® ® RTVll ® + 10% SF1l54 ® (Figures 3,4). Within the first month of immersion bryothere was a large settlement of encrusting bryo zoans on both panels sets. After this initial colonization the barnacles and tunicates became the dominant fouling types on these surfaces. At MMRTS, MMRTS, the the percentage percentage total total coverage coverage did did At not differ differ between between the the silicone silicone formulations formulations not (ANOVA, nn = 4, 4, pP = 0.340). 0.340). (ANOVA, Due to sampling artifacts, the fouling coverage data at the northeastern sites were grouped into bryoorganismal types; for example, encrusting bryo zoans and tubeworms were combined into one organismal group. At NE site BPS, BPS, the total coverage on both coatings increased during the spring and summer seasons and decreased 6). Fouling slightly over the winter (Figures 5, 6). RTV11® RTVll® + 10% coverage of RTVll ® and the RTVll ®+
SF1l54 ® was similar; the only notable differences SF1154® differences in total coverage occurred between November 1999. The fouling on both 1998 and February 1999. formulations at NE site BPS was made-up of a diverse assemblage of the organismal types. The contribuorganismal type that had the greatest contribu tion to the fouling coverage was the tunicates/ "rubbery" bryozoans. The total coverage at NE site MSS on both silicone coatings was similar to that that at at NE NE site site BPS, BPS, although although the the composi composito tion of of the the fouling fouling community community was was different different tion (Figures 7, 7, 8). 8). Fouling Fouling coverage coverage consisted consisted pri pri(Figures marily of sponges/anemones and encrusting marily of sponges/anemones and encrusting bryozoans/tubeworms. The The cyclic cyclic pattern pattern of of set setbryozoans/tubeworms. tlement in the temperate regions was seen with tlement in the temperate regions was seen with peaks on on both both panels panels at at NE NE site site MSS MSS in in the the late late peaks spring. Both Both of of the the silicone silicone coating coating formulations formulations spring. at NE NE site site MSS MSS had had similar similar coverage coverage patterns patterns at over time. The NE immersion sites showed over time. The NE immersion sites showed different seasonal coverage patterns and organisdifferent seasonal coverage patterns and organis mal composition composition of of fouling fouling coverage. coverage. mal
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Adhesion Strength of Oysters, Tubeworms, and Barnacles on Silicone Coatings at at Two Two Exposure Sites In Hawaii, oysters and tubeworms were abun abundant and colonized the test coatings in a quantity sufficient sufficient to make adhesion measurement possi possible. At the FITsite all primary hard fouling organ ble. FIT site all primary organisms (barnacles, tubeworms, and oysters) settled sufficient quantities to allow for comparisons in sufficient coatings. All adhesion measurements measurements between coatings.
were transformed transformed using (ln(x (In(x + + 1)) 1» before before statisstatis tical analyses were performed performed and an ANOVA analysis was used to discriminate statistically significant differences between coatings. significant differences In Hawaii the adhesion strength of both oysters and tubeworms to RTVll®+ RTVll ® + 10% SF1154® SF1154® was slightly less than the adhesion of those organisms to RTVll ® (Figure 9, Table III). This reduction reduction in RTVll® adhesion strength by the addition of oil was not statistically significant = 48, pP= 0.124; significant (oysters, n =
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