Drinking and Na+/K+
ATPase activity during early development of European sea bass, Dicentrarchus
labrax Ontogeny and
short-term regulation following acute salinity changes
S. Varsamos, S.E. Wendelaar Bonga, G. Charmantier, G.
Flik-2004
Journal of Experimental Marine Biology and Ecology, 311(2): 189-200
Abstract:
The short-term osmoregulatory capacity of sea bass (Dicentrarchus
labrax) larvae and juveniles at consecutive developmental stages was
evaluated by an analysis of drinking rates and whole-body and branchial Na+/K+
ATPase activity. The effect of acute salinity stress on those parameters was
assessed from hatching to the juvenile stage. Drinking rate normalised to
body weight (DRbw) decreased throughout postembryonic
development. DRbw was not affected by salinity in yolk sac
larvae. However, significant differences were observed in older larvae and
in juveniles submitted to hypo- and hyperosmotic challenges. Post yolk sac
larvae and juveniles always drink, but at a lower rate in hypoosmotic media
compared to hyperosmotic media. A correlation was established between DRbw
and blood osmolality during the postembryonic development of the sea bass.
Na+/K+ ATPase specific and total activity in whole
larval homogenates decreased from hatching to the 5-mm yolk sac larva stage
and increased in 10-mm stage larvae. The enzyme specific activity in the
gills, from post yolk sac larvae to juveniles, decreased whereas the total
activity increased during the same period. Developing sea bass have a better
capacity to cope with hypoosmotic than hyperosmotic media.