Effects of nitrate availability in two culture media (von Stosch (VSES), and artificial ASP 12-NTA), and nitrogen sources (seawater enriched with nitrate, ammonium or urea in concentrations ranging from zero to 30 µM) were evaluated in two brown morphs (BR-1, BR-2), one light-green morph (LG) and one dark-green morph (DG) of Hypnea musciformis (Wulfen) J.V. Lamour. Higher growth rates of the four morphs were observed in VSES medium. However, artificial ASP12-NTA medium induced tetrasporangium development in DG morph. Growth rates of the four colour morphs followed kinetic of saturation-type nutrient uptake in treatments with urea. In contrast, growth rates of BR-1, BR-2 and LG morphs were inversely proportional to ammonium concentrations, and those higher than 15 µM were lethal. Growth responses of colour morphs of H. musciformis showed intraspecific variations, and they could be used as bioindicators of nitrogen pollution in marine environment by their low tolerance to ammonium.
ammonium; Hypnea musciformis; nitrate; urea
