E. Cataldi

Serum ions concentration and atpase activity in gills, kidney and oesophagus of european sea bass (Dicentrarchus labrax, pisces, perciformes) during acclimation trials to fresh water

Abstract 1. 1. Kidney, oesophagus and gill Na + -K + ATPase activity and serum Na + , K + and Cl − concentrations are evaluated in European sea bass during experimental acclimation to fresh water. 2. 2. Kidney and oesophagus ATPase increase in low salinity and reach a maximum in fresh water. 3. 3. Gill ATPase decreases during the acclimation trials and rises again to normal values after a 3-week stay in fresh water. 4. 4. Na + and K + serum concentrations decrease during the trials and increase back after a 3-week stay in fresh water. 5. 5. The correlations between enzymatic activities, serum ion concentrations, morphological changes and environmental salinity are discussed.

Acclimation trial ofMugil cephalus juveniles to freshwater: morphological and biochemical aspects

SynopsisAcclimation trials ofMugil cephalus juveniles (SL = mean 28.05, sd = 3.54 mm) were performed by means of a gradual transfer to freshwater in 48 h. The adaptation capabilities ofM. cephalus were evaluated using descriptors such as tissue osmolality, chloride cell number, Na+-K+ ATPase activity and morphological aspects of oesophagus and gills. The high survival rate and tissue osmolality regulation demonstrate the adaptation ability of striped mullet of this size. Chloride cell number and osmolality proved to be good markers of functional adaptation. The morphological and biochemical aspects of oesophagus and gills in juveniles are similar to those of the adult, suggesting that osmotic regulatory mechanisms are precociously developed to allow the colonization of eutrophic inland waters.

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.

Hydrobiology and Fish biology

(1986). Hydrobiology and Fish biology. Bollettino di zoologia: Vol. 53, No. sup001, pp. 93-100.