Ontogeny of Osmoregulation and Salinity Tolerance in Two Decapod Crustaceans:Homarus americanusandPenaeus japonicus

Abstract

Osmoregulation and salinity tolerance were studied in larvae and post-larvae of two species of crustaceans. Homarus americanus and Penaeus japonicus, that have different types of embryonic development.In both species, salinity tolerance decreased through the larval stages, was at a minimum at metamorphosis, and increased in post-larval stages. In H. americanus, the lethal salinity for 50% of the animals (24 h LS50) at 20C was about 1 7%o at metamorphosis, and about 10.5-12%o in stages IV and V. In P. japonicus, the 24 h LS50 at 25C was about 25%o at metamorphosis, and about 7-10% from the sixth post-larval stage onwards.In both species, larvae were hyper-osmoconformers and the osmoregulatory pattern changed after metamorphosis to the juvenile/adult type. In //. americanus, stages IV and V slightly hyper-osmoregulated in low salinities. In P. japonicus, post-larvae hyper-hypo-regulated, and their regulatory capacity increased up to the fifth post-larval stage.In young stages of H. americanus and P. japonicus, Osmoregulation and salinity tolerance appear correlated, and are modified at metamorphosis. These results are discussed iih regard to their ecological and physiological implic i md to previous studies on other species.

Effects of reduced salinities on development and bioenergetics of early larval shore crab, Carcinus maenas

“…Among the intrinsic factors, the ontogeny of osmoregulation, especially, needs further investigation, i.e. the development of regulatory structures (Hong, 1988;Bouaricha et al, 1994) and endocrine systems (Charmantier et al, 1988;Bouaricha et al, 1991;Charmantier and Charmantier-Daures, 1991). In our study, larval respiration was in general reduced at low salinities.…”

Low Salinity Rearing of the Pacific White Shrimp Litopenaeus vannamei: Acclimation, Survival and Growth of Postlarvae and Juveniles

“…They reported better survival of juveniles in salinities of 2 ppt and 0 ppt, compared to postlarvae. Other studies in L. vannamei 20 , and other penaeid species such as M. japonicus 4 , P. indicus 10 and L. setiferus 18 have also shown that salinity tolerance increases with PL age. Increased survival seen at the juvenile stages suggests that by this stage L. vannamei develops increased osmoregulatory capacity as has been reported for other decapod crustaceans 4 .…”

“…Other studies in L. vannamei 20 , and other penaeid species such as M. japonicus 4 , P. indicus 10 and L. setiferus 18 have also shown that salinity tolerance increases with PL age. Increased survival seen at the juvenile stages suggests that by this stage L. vannamei develops increased osmoregulatory capacity as has been reported for other decapod crustaceans 4 . PL size has been indicated to be indirectly correlated to a larger gill area, which in turn is thought to represent a better osmoregulatory capacity 1 .…”

Ontogeny of osmoregulation in the grapsid crab Armases miersii (Crustacea, Decapoda)

“…This ontogenic change in the patterns of osmoregulation can be compared with that in other species, and it may be assigned to one of 3 different types that have been proposed (Charmantier et al 1988;review in Charmantier 1998). Armases miersii belongs to the third category, in which the pattern of osmoregulation changes during the postembryonic development.…”

“…The latter occurs in species where metamorphosis is spread over several molts, e.g. in Penaeus japonicus and probably other penaeid shrimps (Charmantier et al 1988). In the literature, there are controversial views of the timing of metamorphosis in brachyurans.…”