Chan Sun Park1 and Eun Kyoung Hwang2
1 Department of Marine and Fisheries Resources, Mokpo National University, Muan 58554, Republic of Korea
2 Fisheries Seed and Breeding Research Institute, National Institute of Fisheries Science, Haenam 59002, Republic of Korea
Discoloration of Pyropia refers to deterioration of the quality of laver as well as the production due to the color change and detachness of frond with lack of nutrients in seawater. In this study, we investigated that the critical concentration of nitrogen causing the discoloration of P. suborbiculata, the effective period for the recovery of the discolered thalli, and the appropriate nutrient concentration. To calculate critical nutrient concentration that causes the discoloration of the thalli, culture experiment was conducted at 5 DIN concentrations (30, 50, 70, 90, 110 mg L-1) for 14 days. To test recovery of discolored thalli, culture experiment was conducted at 4 NH4-N concentrations (10, 20, 40, 60 mg L-1) for 96 hours. After 8 days culture, discoloration of thalli was induced according to the nutrient concentration between 70 and 90 mg L-1of dissolved inorganic nitrogen. When the nutrient deficiency period was less than 10 days, the color recovery of the discoloration-induced thalli was significantly recovered within 48~72 hours when NH4-N was treated with 20 ppm. In this study, we revealed that the discoloration of Pyropia caused by the lack of nitrogen concentration in culture farms can be restored by supplying nitrogen within an appropriate period and concentration.