Ion levels in the gastrointestinal tract content of freshwater and marine–estuarine teleosts

摘要: This study investigated the relationship between ion levels (Na+, Cl−, K+, Ca2+, and Mg2+) in fluid phase total chyme of contents gastrointestinal tract segments freshwater marine–estuarine teleosts collected different salinities (0–34 ppt) estuarine portions Sao Goncalo channel, southern Brazil. In addition, relative contribution feeding osmoregulation to ionic content each portion fishes ambient was analyzed. There no salinity when considering all species together. However, there a significant positive two fish (Micropogonias furnieri Genidens barbus) three or more salinities. most species, changed throughout tract, suggesting absorption, but ionoregulatory mechanisms seem vary according species.