Evaluation of the bioremediatory potential of several species of the red alga Porphyra using short-term measurements of nitrogen uptake as a rapid bioassay

Rates of inorganic nitrogen uptake by three Northeast US and three Asian species of Porphyra were compared in short-term incubations to evaluate potential for longer term and larger scale examination of bioremediation of nutrient-loaded effluents from finfish aquaculture facilities. The effects of nitrogen (N) species and concentration, temperature, acclimation history, and irradiance were investigated. Uptake rates increased ca. nine-fold from 20 to 150 mu M N. Nitrate and ammonium uptake occurred at similar rates. Irradiance had a strong effect, with uptake at 40 mu mol photons m(-2) s(-1) only 55% of uptake at 150 mu mol photons m(-2) s(-1). N- replete tissue took up inorganic nitrogen at rates that averaged only 60% of nutrient-deprived tissue. Although there were species ( P. amplissima > ( P. purpurea = P. umbilicalis)) and temperature effects (10 degrees C > 5 degrees C > 15 degrees C), interactions among factors indicated that individual species be considered separately. Overall, P. amplissima was the best Northeast US candidate. It took up ammonium at faster rates than other local species at 10 and 15 degrees C, two temperatures that fall within the expected range of industrial conditions for finfish operations.