Donatella Crosetti

Variations in renal morphology during adaptation to salinities in tilapias

SynopsisFifteen days oldOreochromis niloticus andO. mossambicus juveniles were gradually adapted to 10, 20, 30 and 35 ppt sea water. Kidney morphology was observed after transfer to higher salinities and compared with freshwater controls. Despite differences in salinity tolerance, both species have similar transformations when transferred at high salinity, particularly reduction of the glomerular area after 2 months adaptation to sea water, and change in tubule morphology.

Oesophagus structure during adaptation to salinity in oreochromis niloticus (Perciformes, pisces) juveniles

Abstract Fifteen days old Oreochromis niloticus juveniles were gradually adapted to 10, 20, 30 and 35‰ sea water. The morphology of the oesophagus epithelium was observed at different intervals after transfer to higher salinities. At 10‰, no changes are evident compared to fresh water controls. Regions of single columnar epithelium, reported to play a role in ion trasport, appear within the normal pluristratified one at 20, 30 and 35‰ four weeks after transfer from fresh water. These modifications widen in individuals left for longer at high salinities.