Effects of salinity on the growth and mucous cells of the abalone Haliotis diversicolor Reeve, 1846

Abstract

This study was conducted to determine the influence of salinity on the growth of abalone Haliotis diversicolor Reeve, including the density and size of mucous cells. Abalone individuals were reared in the laboratory at salinities of 20, 25, 31, 35 and 40 ppt. The mucous cells of the lips, gills and digestive gut of H. diversicolor, which react to some forms of stress such as suboptimal salinity, were characterized following staining with Alcian Blue–Periodic Acid–Schiff`s Reagent (AB–PAS). The specific growth rate in wet weight and shell length of H. diversicolor were highest at 31 ppt and lowest at 20 ppt (0.52 vs 0.15% d−1, and 0.058 vs 0.021 mm d−1, respectively). The abalone H. diversicolor tolerated salinity fluctuations within the range of 20–40 ppt, but growth was optimum at 25–35 ppt. Mucous cells of the lips and gills showed significant differences (ANOVA, df = 4, P = <0.001) in cell density and cell size, being less dense and larger at 31 ppt than at 40 ppt, which could be an effect of osmotic and ionic regulation. Consistent with reports in literature, salinity ranges of 25–35 ppt are suitable for growth of H. diversicolor. Results of this study indicated that areas with such salinity are favorable for stock enhancement and mariculture of the abalone H. diversicolor.