Salinity tolerance of Haliotis diversicolor supertexta at different salinity and temperature levels

Abstract

Juvenile abalones, Haliotis diversicolor supertexta Lischke maintained in different environmental regimes (25, 30 and 35‰ combined with 20, 25 and 30°C) were examined for salinity tolerance by increasing and decreasing salinity at a rate of 2‰/h. They were also examined for the LS50 (median lethal salinity) when transferred directly into a series of higher salinity (32–48‰) and lower salinity (9–25‰) water baths. The 50% CSMax (critical salinity maximum), USTL (upper salinity tolerance limit), 50% CSMin (critical salinity minimum) and LSTL (lower salinity tolerance limit) increased directly with salinity, but were inversely related to temperature. The juveniles maintained in 25°C and 25, 30 and 35‰ had 50% CSMin–50% CSMax of 11.2–41.8‰, 12.5–43.9‰ and 13.5–49.8‰, respectively. The juveniles maintained in 25‰ and 30°C survived salinity of 14–33‰, and those maintained in 35‰ and 20°C survived salinity of 20–45‰, when salinity was decreased or increased gradually. It is suggested that H. diversicolor supertexta juveniles maintained in 35‰ or higher at 20°C or lower survive salinity higher than 45‰ when salinity is increased. It is also suggested that the juveniles maintained in 25‰ or a lower salinity at 30°C or a higher temperature survive salinities lower than 14‰ when salinity is decreased.