Formation and calcification of biofilms on antifouling paints in hard waters

Abstract

The deposition of biofilms on a commercial antifouling paint and a control paint was studied on panels immersed in a hard‐water river (Great Ouse) and an adjacent marina during the summer months of 1991. Various water analyses were performed including pH, alkalinity, conductivity, major anions and cations. From the measured data, the saturation index, PCO2 and charge balance of the waters were calculated. There was a reduction in the dry weight of biofilms on all panels coated with antifouling paint compared to the control. In the marina, the dry weight of the predominantly algal biofilm decreased with increasing depth. Calcium carbonate was deposited within all biofilms and a significant linear relationship was shown between CaCO3 and organic weight in both marina and river. However, the proportion of CaCO3 present within biofilms formed in the marina was greater than within those from the river. These results are discussed in relation to chemical and biologically mediated precipitation of CaCO3.