[en] Senegalese sole juveniles were held into flow-through respirometers and submitted to a sudden salinity change. Briefly, 40-50 g body weight fish were kept into chambers with initial salinity of 37.5 ppt (the same as in culture tanks) and, after an acclimation of 4 hours, the salinity was changed to 5 or 55 ppt. A control group did not experience any salinity alteration. Oxygen consumption was registered every 14 min and fish were sampled (gill biopsy and plasma) at different times (at t=4.5 h and t=7 h in order to determine gill Na+,K+- ATPase activity and plasma cortisol concentration. At t=4.5 h, oxygen consumption showed an inverse relationship with salinity, while gill Na+,K+- ATPase activity increased. Plasma cortisol levels presented a "U-shaped" relationship with salinity. At 7 h, oxygen consumption was higher in the control group, while cortisol and gill Na+,K+- ATPase activity varied in parallel to salinity. Our results suggest that sudden salinity changes evoked an acute stress situation (cortisol increased up to 15x over the basal level) which was slightly attenuate after 7 h. Fish quickly adapted its respiration rate to the new environmental conditions and this rate returned progressively to its normal values after the shock. Regarding enzyme activity, fish increased (55 ppt) or decreased (5 ppt) the ATPase activity depending on the salinity, as described in other studies. This work was supported by Interreg Project 0251_ECOAQUA_5_E, financed by the EDRF (European Regional Development Fund). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua. <span lang="EN"> </span> &nbsp;

[es] Juveniles de lenguado senegal&eacute;s fueron mantenidos en respir&oacute;metros y sometidos a un cambio brusco de salinidad. Resumidamente, peces de 40-50 g se mantuvieron a una salinidad de 37.5 ppt y, despu&eacute;s de una aclimataci&oacute;n de 4 horas, la salinidad se vari&oacute; a 5 &oacute; 55 ppt. Un grupo control no experiment&oacute; ninguna alteraci&oacute;n. El consumo de ox&iacute;geno fue registrado cada 14 min y los peces fueron muestreados (plasma y branquias) a diferentes tiempos (t=4.5 h y t=7 h para determinar la actividad Na+,K+- ATPasa branquial la concentraci&oacute;n de cortisol en plasma). A t=4.5 h, el consumo de ox&iacute;geno fue inversamente proporcional con la salinidad, mientras que la actividad Na+,K+- ATPasa branquial creci&oacute;. El cortisol plasm&aacute;tico present&oacute; una curva en forma de "U" en funci&oacute;n de la salinidad. A t=7 h, el consumo de ox&iacute;geno fue mayor en el grupo control, mientras que la Na+,K+- ATPasa branquial vari&oacute; en paralelo con la salinidad. Nuestros resultados sugieren que un cambio brusco de salinidad provoca una situaci&oacute;n de estr&eacute;s agudo (cortisol aumenta 15 veces su valor basal), que se aten&uacute;a ligeramente despu&eacute;s de 7 h. Los peces r&aacute;pidamente adaptan su tasa respiratoria a esta nueva condici&oacute;n ambiental y luego var&iacute;a progresivamente a su valor inicial. Respecto a la actividad enzim&aacute;tica, los peces aumentaron (55 ppt) o disminuyeron (5 ppt) la actividad ATPasa en funci&oacute;n de la salinidad, como se ha descrito en previos trabajos. Este trabajo fue apoyado por el proyecto Interreg 0251_ECOAQUA_5_E , financiado por el FEDER (Fondo Europeo de Desarrollo Regional). www.juntadeandalucia.es/agriculturaypesca/ifapa/ecoaqua.