Saline preferendum for the
European sea bass, Dicentrarchus labrax, larvae and juveniles: effect
of salinity on early development and sex determination
E. Saillant, A. Fostier, P. Haffray, B. Menu, B.
Chatain-2003
Journal of Experimental Marine Biology and Ecology, 287(1) : 103-117
Abstract:
The sea bass, Dicentrarchus labrax, is an
eurhyaline marine fish. Juveniles of this species are known to frequent
estuaries and lagoons where salinity is lower than in the open sea. Sex
determination occurs during this phase of fish life and has been shown
labile and sensitive to environmental factors. In this work, the effect of
rearing salinity on sex determination and early development of the sea bass
was investigated. An excess of males (87%) was found in all groups and the
salinity level [(natural sea water salinity, mean: 37 ppt) vs. (15 ppt)],
when maintained constant, had no effect on the sex-ratio. The transfer from
low to high salinity at 93 days post-fertilization (p.f.) increased the
percentage of males (93%) suggesting that sexual differentiation in this
species may be influenced by such an osmotic stress. Growth was improved by
a 15 ppt salinity at the beginning of larval rearing (14 days p.f.) and at
the end of pre-growing (234–458 days p.f.), periods during which low
temperatures were applied. Survival during larval rearing and nursery were
also improved in the groups reared at low salinity and so was swimbladder
inflation. These results show that sea bass juveniles have a low saline
preferendum, a finding that corresponds to the conditions they actually
encounter in the wild during their juvenile ecophase; sex determination is
not directly modulated by the salinity level but seems to be subjected to
complex environmental regulations.
(Laboratoire
de Recherche en Pisciculture Marine, IFREMER, Chemin de Maguelonne 34250,
Palavas-les-Flots, France, e-mail: esaillant@wfscgate.tamu.edu)