Acute salinity tolerance of native and introduced freshwater gastropods of Tabasco, Mexico

Abstract

Background. The increase of salinity in continental ecosystems is a factor influencing organisms distribution, abundance, and development. Understanding how tolerance to environmental stress varies among populations helps to predict the effects of climate change on species locally adapted to their abiotic environment. Goals. Assess the effect of salinity on 4 native and 2 introduced gastropod species in Tabasco, by means of their LC50 and LC90, and LT50 and LT90. Methods. Salinity concentrations from 0-15 g/L were tested to determine LC50 and LC90 and tolerance ranges to acute salinity in 4 native and 2 introduced gastropods. Each concentration had 3 replicates with a control and 20 gastropods in each one. Mortality was quantified every hour up to 12 hours. The number of active mollusks was used as a salinity tolerance index. Results. Aroapyrgus clenchi ? 0.30 g/L and Pyrgophorus coronatus ? 1.00 g/L were the least tolerant species, while Pomacea flagellata, Tarebia granifera, and Melanoides tuberculata ? 5 g/L and Mexinauta impluviata ? 6 g/L were the most tolerant. Correlation between concentration and lethal time was inverse and significant. Conclusions. For the introduced species Tarebia granifera and Melanoides tuberculata, acute tolerance to salinity was not significantly different than Mexinauta impluviata and Pomacea flagellata; whereas all 4 were significantly different than Pyrgophorus coronatus and Aroapyrgus clenchi that are less tolerant to salinity.