Abstract
IN LABORATORY experiments for eleven days, the effect of dissolved ammonium and phosphate on the absorption, growth, and nutritional content of Dictyota dichotoma was examined to determine their potential application as a nutrient biofilter. Five combinations of phosphates and ammonium concentration (0.8/8, 2/20, 4/40, 6/60, and 8/80 mu mol/L) were added to Sterile seawater. Molar phosphorus/ nitrogen ratio was 1:10. Over a 24hrs period, 69.2-99.9% of the available ammonium and 90.7-100% of the available phosphate were taken up by D. dichotoma. The highest specific growth rate was 9.3 +/- 0.2% day(-1) at 6/60 mu mol/L while the lowest was 5.11 +/- 0.3% day(-1) at mu mol/L. On the other hand at 8/80 mu mol/L the biomass was decreased in the second day of treatment Total soluble carbohydrate, total soluble protein, and total lipids of the tested D. dichotoma were significantly increased with the increase of PO4-3/NH4+ concentration and greater than their respective initial content. The highest averages of total soluble carbohydrate (TSC) (9.79 +/- 0.45% dry wt.), total soluble protein (TSP) (16.3 +/- 0.32% dry wt.) and total lipid (8 +/- 0.30% dry wt.) were observed at the concentration of 6 mu mol/L for PO4-3 and 60 mu mol/L for NH4+. Based on these results, D. dichotoma has a strong absorption capacity for ammonium & phosphates, and as bioremediator in eutrophic environments can be a promising applicant.