The effects of nitrate and phosphate on growth of algae, Ulva rigida

Nutrients especially nitrate and phosphate are the main limiting factors of algal growth in aquatic ecosystems. The present study was conducted to examine the effects of different concentrations of nitrate and phosphate simultaneously on growth of macro algae, Ulva rigida. For this purpose, algae were fed various concentrations of nitrate and phosphate during ۲۸ days in ۳۰۰ L tanks in the form of ۴ experimental treatments with three replicates. The experimental treatments were: T۱: ۱۰ mg L-۱ NO۳+۵ mg L-۱ PO۴, T۲: ۲۰ mg L-۱ NO۳+۱۰ mg L-۱ Po۴PO۴, T۳: ۳۰ mg L-۱ NO۳+۱۵ mg L-۱ PO۴, T۴: ۴۰ mg L-۱ NO۳+۲۰ mg L-۱ PO۴ and one control treatment was considered. According to the results, all experimental treatments showed increased growth compared to the control treatment (p<۰.۰۵). There were no significant differences in growth of algae between T۳ and T۴ (p>۰.۰۵). The highest values of gain weight (۸۸.۰۲±۰.۷۴ g, nearly ۱۷ times more than the initial weight) and daily growth percent (۶۰.۵۷±۱.۲۹ %) were observed in algae of T۳ and then T۴ (daily growth percent: ۴۲.۹۵±۱.۵۶ %). In conclusion, our results suggest that a concentration of ۳۰ mg L-۱ NO۳+۱۵ mg L-۱ PO۴ is more suitable for the growth of macro algae, U. rigida.

Keywords:

Macro algae , Ulva rigida , Concentration , Nitrate , Phosphate