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 parts per thousand combined with 20, 25 and 30 degrees C) were examined for salinity tolerance by increasing and decreasing salinity at a rate of 2 parts per thousand/h. They were also examined for the LS50 (median lethal salinity) when transferred directly into a series of higher salinity (32-48 parts per thousand) and lower salinity (9-25 parts per thousand) 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 degrees C and 25, 30 and 35 parts per thousand had 50% CSMin-50% CSMax of 11.2-41.8 parts per thousand, 12.5-43.9 parts per thousand and 13.5-49.8 parts per thousand, respectively. The juveniles maintained in 25 parts per thousand and 30 degrees C survived salinity of 14-33 parts per thousand, and those maintained in 35 parts per thousand and 20 degrees C survived salinity of 20-45 parts per thousand, when salinity was decreased or increased gradually. It is suggested that H. diversicolor supertexta juveniles maintained in 35 parts per thousand or higher at 20 degrees C or-lower survive salinity higher than 45 parts per thousand when salinity is increased. It is also suggested that the juveniles maintained in 25 parts per thousand or a lower salinity at 30 degrees C or a higher temperature survive salinities lower than 14 parts per thousand when salinity is decreased. (C) 2000 Elsevier Science B.V. All rights reserved.