title: Effect of low salinity on the yellow clam Mesodesma mactroides.
abstract: The aim of this study was to determine the lethal salinity (LC50) for the yellow clam Mesodesma mactroides (Bivalvia: Mesodesmatidae) and identify histopathological alterations that could be used to diagnose structural changes in clam tissue. Clams in two size classes (adults and juveniles) were placed in 10 L chambers and exposed to salinities of 35, 30, 25, 20, 15, 10, and 5 g/L. There were triplicate chambers with seven clams each for each salinity. The LC50 values for a 48 h exposure were 6.5 g/L and 5.7 g/L for adults and juveniles, respectively. For a 96 h exposure, the LC50 values were 10.5 g/L for adults and 8.8 g/L for juveniles. The histological examination of yellow clams exposed to 10 g/L for 96 h showed intercellular oedema and necrotic foci in the epithelium of the digestive gland and occlusion of the lumen of the digestive gland. In conclusion, M. mactroides can be characterised as a moderately euryhaline species, tolerating salinities from 35 to 15 g/L.
authors.affiliation: Estação Marinha de Aquacultura, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.
authors.forename: Y B M
authors.initials: YB
authors.lastname: Carvalho
authors.affiliation: Estação Marinha de Aquacultura, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.
authors.forename: L A
authors.initials: LA
authors.lastname: Romano
authors.affiliation: Estação Marinha de Aquacultura, Instituto de Oceanografia, Universidade Federal do Rio Grande, Rio Grande, RS, Brazil.
authors.forename: L H S
authors.initials: LH
authors.lastname: Poersch
mesh_terms: D000818:Animals; D049872:Bivalvia; D007928:Lethal Dose 50; D054712:Salinity; D013997:Time Factors