Inhibition of adhesion of Ulva spores by organic biocides for marine anti-fouling paints

Abstract

the growth rate of Ulva, the settlement of Ulva spore and the amount of adhesive pad. The fluorescence images were obtained by fluorescence microscope because chlo-rophyll structure can absorb the light (Blue) and emit the fluorescence (Red) <Fluorescence image>. Then the images are converted by imageJ program and the number of settled spore on substrate can be calculated. Among the various biocides, we tested the 7 sample biocides selected

Copper pyrithione(CuPT), Zinc pyrithi-one(ZnPT), Preventol A5S(P-A5S), Preventol A6(P-A6), SeaNine 211N (S-211N), Zineb, and Econea(EC). SEM image analysis was performed to figure out the effect of biocide when the spore tries to settle on the substrate. These studies demonstrated that the growth rate of Ulva , the attachment densities of Ulva spores, and the amount of adhesive pad in the various biocide solutions can use as a quantitative analysis method of antifouling system. Furthermore, the three analyses methods could be the standard for antifouling data-base

Biofouling is the accumulation of a variety of marine plants and animals on the surface of submerged struc-tures. Specifically, the buildup of biofouling on marine vessels causes a significant problem. The accumula-tion of biofoulers on ship hulls increases the hydrodynamic drag and decreases the ship speed which can in-crease the fuel consumption. Besides, an increased cleaning costs and time-out of service are also required. The total annual global cost due to the biofouling is estimated at approximately $3 billion. A major part of this expense is an increased fuel consumption which is estimated at several hundreds of thousands of gallons. Currently, the most widely used antifoulants are biocides. Until 1980s, Tributyltin (TBT) was outstanding antifouling biocide with high efficiency. However, TBT has been prohibited until 2008 because it causes se-vere reproductive failure in marine animals. Many various biocides were developed, therefore, to find out more effective antifouling biocides and to figure out the optimal combination of various biocides for anti-fouling based on the experimental database. An alga, especially Ulva, is dominant kind of soft fouling organ-ism. Therefore, Ulva prolifera was used as a test organism. Ulva was cultured in two systems by using the growth chamber incubator. One was summer environment which is the condition of reproduction for 16h at 20 $^\circ$C: 8h Light:Dark(LD) cycle, illumination 4000lux. The other was winter which is for growth condition for 8h at 10$^\circ$C:16h LD cycle, illumination 1000lux. Ulva spores were collected in summer condition. To compare the efficiency of biocides, it needs to establish the analysis system. The quantitative analysis of antifouling can investigate with three different methods