Effect of terrestrial plant extracts on the fouling community at Mar del Plata harbour

JORGE PALERMO; MÓNICA GARCÍA; MIRIAM PÉREZ; MARIANELA SÁNCHEZ; GUILLERMO BLUSTEIN

Río de Janeiro

Simposio; Latin American Biodeterioration and Biodegradation Symposium; 2016

Immersion of a solid substrate in seawater produces a rapid adsorption of dissolved organicmatter on its surface. The resulting organic "conditioning" film is glycoprotein or "humic" innature and makes the surface wettable. Bacteria, diatoms and spores attach onto the substrateand this growing lawn, composed of dead and living cells and their secreted slime togetherwith the macromolecular film, constituted the so-called primary film. Larvae of macrofoulers(sessile marine organisms such as polychaetes, mussels, barnacles, tunicates) then attach tothe microfouling film.Antifouling paints have been for long time the most effective method to protect ship hulls.They prevent biofouling by releasing biocides (such as organotins or copper compounds) at aconstant rate. However, their use has been restricted in many countries due to human healthissues related to its application and the growing pollution of the environment.Several bioactivities of secondary metabolites from terrestrial plants are well known, andthese can turn them into promising candidates as antifouling compounds. In this work, theantifouling activity of ethanolic extracts from Verbena officinalis and Tillandsia tenuifoliaincluded in soluble matrix paints was studied. For the preparation of the antifouling paint,colophony and oleic acid were dissolved in a xylene/white spirit mixture. Then, ethanolicextracts (1.5% v/v) and pigments were added and dispersed. Three coats of paint were appliedon sandblasted acrylic tiles. Panels (treatments and controls) were hung in a marina in Mar delPlata harbour (Argentina). After 45 days exposure in the sea, coatings containing V. officinalisor T.tenuifolia extracts significantly inhibited total cover percentage of the main foulingorganisms related to controls (p<0.05). Antifouling paints affected settlement but in varyingdegree. Adhesion of calcareous tubeworms (Hydroides elegans) and sandtube builders(Polydora sp.) was strongly inhibited by V. officinalis and reduced by T.tenuifolia. On theother hand, the common algae Enteromorpha intestinalis and Ectocarpus sp., the bryozoanBugula neritina and colonial ascidian Botryllus sp. were affected in a similar way, i.e.,reduction in settlement related to controls. It is important to remark that the soft coralAntothoe chilensis was completely inhibited by both paints.These preliminary results showed that V. officinalis and T.tenuifolia extracts can be employedas bioactive agents for antifouling paints.