All data are presented as means ± the standard error of the mean
(SE). Plasma osmolality, solute concentrations and tissue-specific NKA
activity were analysed by one-way ANOVA and pairwise post hoc t-tests
(Holm adjusted alpha level). Rectal gland masses were compared
across treatments using ANCOVA with body mass as the co-variate.
Within salinity treatments, plasma osmolality and environmental
osmolality were compared using one-sample t-tests. All analyses
were run using R (R Core Team, 2013).