Abstract
Ecological concerns about antifouling paints containing non-green tin and copper compounds have highlighted the need for environmentally friendly alternatives. We report here a field test conducted in estuarine waters over two months designed to evaluate the efficiency of a number of active natural and man-made chemical ingredients added into a silicon-polyurethane marine paint. Early steps of biofouling in cold seawater of the St. Lawrence Estuary (Canada) were observed. Analyses, including dry biomass, flow cytometry and spectrofluorimetry, demonstrated a short-term antibacterial action of chitosan-based paints although no significant anti-algal action was observed. Cuprous oxide paints were efficient against bacteria and algae invasion in the first two weeks, especially those with added organic biocides such as isothiazolone and copper pyrithione. However, the overall dry biomass and chlorophyll a content were similar for all chitosan-and copper-based paints after 63 days. Microscopic observations revealed variation in the highly diverse benthic diatom population including species Navicula, Melosira, Cocconeis, Nitshzcia, Fragilaria and Amphora. Results suggest no real long-term efficiency for tested antifouling paints and highlight a particular need for green antifouling ingredients that are active under northern estuarine conditions.
Highlights
Being a source of environm ental and economical problems, the invasive bi ofouling process creates adverse effects on all immersed structures limiting their utilization and accelerating their corrosion
Unfortunate ly, TBT was found to be the m ost toxic substance ever introduced in the m arine environ ment, with harmf ul effects to non-target organism s [2 ]
The first aim of this work was to test the efficiency of finely ground (60 m esh) chitosan incorporated as an antifouling additive into a polyurethane marine paint lacking any other biocide
Summary
Being a source of environm ental and economical problems, the invasive bi ofouling process creates adverse effects on all immersed structures limiting their utilization and accelerating their corrosion. Unfortunate ly, TBT was found to be the m ost toxic substance ever introduced in the m arine environ ment, with harmf ul effects to non-target organism s [2 ]. Tin-free alternative antifouling chemical agents for use in the aquatic environment have been a topic of increasing concern over the past years as stable degradation prod ucts could cause environm ental problem s by their increasing concentrations [1,4]. Com pounds isolated from m arine organism s such as b acteria, algae, cnidaria, bryozoa, chordate an d other sessile ben thic invertebrate s were tested again st biofouling [4,5,6]. A r ecent example is given by Tsoukatou et al [7], where sponge m etabolites a nd their sy nthetic derivatives were tested in laboratory against fouling organisms
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