THE EFFECTS OF TEMPERATURE ON THE ABSORPTION EFFICIENCY OF NITROGEN AND PHOSPHORUS AND PHOTOSYNTHETIC PHYSIOLOGICAL CHARATERISTICS IN FOUR MACROALGAE SPECIES

Purifying wastewater with biological methods is highly important in the field of ecological recirculating aquaculture. To study the effects of temperature on the absorption of nitrogen and phosphorus and photosynthetic performance of macroalgae in sea water, four species including Ulva fasciata, Ulva intestinalis, Gracilaria lemaneaformis and Pyropia haitanensis were cultured under four temperature conditions (15, 20, 25 and 30℃). The results showed that: (1) most N and P had been absorbed by the four macroalgae species, and the absorbing ability from high to low is Ulva intestinalis>Ulva fasciata>Pyropia haitanensis>Gracilaria lemaneaformis; (2) extremely high and low temperature will limit the absorbing of N and P, growth, relative electron transfer rate, and chlorophyll fluorescence in four macroalgae species; (3) U. fasciata and U. intestinalis were the best choices due to their high absorption rates of N and P and the tolerance of a wide temperature range; (4) nitrogen and phosphorus could be completely absorbed within 48h by the four macroalgae species. To promote algal growth, improve the removal efficiency of nutrients, as well as prevent secondary pollution caused by nutrition limited negative growth of macroalgae, it’s better to replace the wastewater within 24—48h, or apply the circulation mode in the process of wastewater treatment.