Modelling nitrogen and phosphorus recovery potential by Ulva fasciata

Abstract

This study investigated the nitrogen and phosphorus uptake efficiency and recovery potential by the cosmopolitan macroalga Ulva fasciata. An equation to estimate biomass production, as well nitrogen and phosphorus recovery, by Ulva species is further proposed. Results showed that U. fasciata removed 99 % of nitrogen (NH4-NO3) and 22% of phosphate dissolved in water. Tissue nitrogen, phosphorus and chlorophyll-a increased 73, 20 and 244 %, respectively, demonstrating rapid assimilation of nutrients fueling U. fasciata’s growth (5.69 % day-1). The constructed equation correlating fresh weight and area showed that 0.21- and 11.35-tons ha-1 year-1 of phosphorus and nitrogen could be recovered and that 3.47 tons of dry biomass could be produced. Tissue data add to the understanding of physiological effects of nutrient availability in U. fasciata. The efficient removal of dissolved nitrogen and phosphorus represents an important ecosystem service with potential for production of value-added by-products.