Effect of salt and brine-beet juice de-icer on osmoregulatory physiology of the freshwater amphipod Hyalella azteca (Saussure, 1858) (Amphipoda: Hyalellidae)

Abstract

Abstract The anthropogenic salinization of freshwater is concerning because it can negatively impact the success and survival of freshwater animals. Road salt (NaCl) in cold climates contributes to salinization and organic based de-icers have been developed to mitigate the effects of NaCl on freshwater. One of these de-icers is sugar beet juice, and few studies have examined its effects on freshwater animals. We exposed Hyalella azteca (Saussure, 1858), a freshwater amphipod, to different concentrations of NaCl (salt-contaminated water or SCW) and a NaCl brine and beet-juice mixture used as a de-icing product (brine-beet juice de-icer, BBJD). The LC50 of NaCl on H. azteca was 12.8 g l–1 and for BBJD was 4.6% (which at that percentage contained ~ 4.2 g l–1 Na+). Sub-lethal doses of SCW elevated hemolymph Na+ and BBJD exposure resulted in elevated K+ concentration as well as acidification of the hemolymph. Both Na+/K+ ATPase (NKA) and V-type H+-ATPase (VA) were localized to the coxal gills, whereas only NKA was found in the sternal gills. There was a qualitatively apparent decrease in expression of NKA in the gills of SCW-treated amphipods. NKA and VA expression qualitatively increased with BBJD exposure in the gut. The NKA and VA activity in whole-body homogenates was lower in BBJD and SCW. Results show that Hyalella azteca responds to SCW and BBJD by altering parameters of ionoregulatory physiology in different ways.