02832nas a2200241   4500008004100000022001400041245016400055210006900219260001300288300001100301490000700312520206900319653001402388653001202402653001402414653001902428653001302447653001502460653003102475100001402506700001802520856005202538       2008                        eng d  a0090-434100aAmeliorating effect of chloride on nitrite toxicity to freshwater invertebrates with different physiology: a comparative study between amphipods and planarians0 aAmeliorating effect of chloride on nitrite toxicity to freshwate  c2008 Feb  a259-650 v543 a<p>High nitrite concentrations in freshwater ecosystems may cause toxicity to aquatic animals. These living organisms can take nitrite up from water through their chloride cells, subsequently suffering oxidation of their respiratory pigments (hemoglobin, hemocyanin). Because NO(2)(-) and Cl(-) ions compete for the same active transport site, elevated chloride concentrations in the aquatic environment have the potential of reducing nitrite toxicity. Although this ameliorating effect is well documented in fish, it has been largely ignored in wild freshwater invertebrates. The aim of this study was to compare the ameliorating effect of chloride on nitrite toxicity to two species of freshwater invertebrates differing in physiology: Eulimnogammarus toletanus (amphipods) and Polycelis felina (planarians). The former species presents gills (with chloride cells) and respiratory pigments, whereas in the latter species these are absent. Test animals were exposed in triplicate for 168 h to a single nitrite concentration (5 ppm NO(2)-N for E. toletanus and 100 ppm NO(2)-N for P. felina) at four different environmental chloride concentrations (27.8, 58.3, 85.3, and 108.0 ppm Cl(-)). The number of dead animals and the number of affected individuals (i.e., number of dead plus inactive invertebrates) were monitored every day. LT(50) (lethal time) and ET(50) (effective time) were estimated for each species and each chloride concentration. LT(50) and ET(50) values increased with increases in the environmental chloride concentration, mainly in amphipods. Results clearly show that the ameliorating effect of chloride on nitrite toxicity was more significant in amphipods than in planarians, likely because of the absence of gills (with chloride cells) and respiratory pigments in P. felina. Additionally, this comparative study indicates that the ecological risk assessment of nitrite in freshwater ecosystems should take into account not only the most sensitive and key species in the communities, but also chloride levels in the aquatic environment.</p>
10aAmphipoda10aAnimals10aChlorides10aLethal Dose 5010aNitrites10aplanarians10aWater Pollutants, Chemical1 aAlonso, A1 aCamargo, J, A  uhttps://continenticola.myspecies.info/node/1720