red algae have halogen-containing m

red algae have halogen-containing metabolites(bromine and/or iodine,sometimes even chlorine)in their tissues,and it is believed that they serve anti-bacterial functions in addition to a function in deterring herbivory.these compounds indicate allelopathic interaction between red algae and their environment(fenical,1975).other algae may have similar positive or negative affects on other organisms.in aquaria with additions of iodide or iodine,the growth of such red seaweeds may curb the growth of fungi,pathogenic bacteria,other algae or cyanobacteria.