Active substances from Ceramium botryocarpum used as antifouling products in aquaculture

Epiphytes and fouling organisms induce problems in aquaculture, reducing yield of open-water and on-shore farms. By weighing down materials, fouling can also cause equipment failure. The presence of Ceramium botryocarpum (Rhodophyta, Ceramiales) in tank cultures (Innovalg, France) significantly limits the establishment of opportunist green algae such as Cladophora, Bryopsis or Ulva usually disturbing the cultures. In order to demonstrate the antifouling activity of substances released by C. botryocarpum, the activities of different extracts have been tested on representative marine species such as marine bacteria, phytoplankton, and spores of macroalgae. The extracts from spring strongly inhibit the development of marine bacteria, phytoplankton and spores of Ulva at concentrations between 25 and 150 μg mL− 1. These results confirm the presence of active substances in C. botryocarpum. No significative trend on the variation in the antifouling activity from September to July has been highlighted. Compared with toxic biocides commonly used in antifouling paints, natural extracts of Ceramium present no cytotoxicity. Active substances from C. botryocarpum could be used to fight against bacterial and algal fouling problems in aquaculture systems.