Documentation of Yields of Laver Porphyra After Treating with Acidified Seawater and High Salinity Seawater to Suppress Red Rot Disease
Ken-ichi Sakaguchi*1, Chan Sun Park*2, Makoto Kakinuma*2, and Hideomi Amano*2
A series of treatments, designed to increase the yield of harvested laver Porphyra infected with red rot disease, were compared. Treatments examined included the effects of washing thalli for 5 min with acid seawater (adjusted to pH 2.0), washing with high salinity seawater (15% and 20% salt), and washing with a combination of acid seawater and high salinity seawater (20% salt). Experiments were conducted at both 8oC and 15oC. Zoospores were inoculated into seawater (5000 spores/L) and after 3 days the extent of the infection of the Porphyra thalli was measured. Thalli were then treated with acidified seawater, high salinity seawater or a combination of both, and grown in cultivation tanks containing normal seawater (3.0% salt) at 8oC (ca. water temperature of winter) or 15oC (ca. water temperature of autumn). Cultures were grown for 5 weeks and thalli were treated weekly. At 15oC, washing with both acidified water and high salinity seawater (20% salt) was the most effective treatment yielding a 2.1 fold increase in harvest relative to controls (untreated). At 8oC, acidified seawater treatment was the most effective giving a 1.7 fold increase in yield.
*1 Fisheries Research Division, Mie Prefectural Science and Technology Promotion Center
*2 Faculty of Bioresources, Mie University