Water calcium concentration modifies whole-body calcium uptake in sea bream larvae during short-term adaptation to altered salinities.
Whole-body calcium uptake was studied in gilthead sea bream larvae (9-83 mg) in response to changing environmental salinity and [Ca2+]. Calcium uptake increased with increased fish size and salinity. Fish exposed to calcium-enriched, diluted seawater showed increased calcium uptake compared with fish in diluted seawater alone. Calcium uptake was unchanged in Na(+)-enriched, diluted seawater. Overall, [Ca2+], and not salinity/osmolarity per se, appears to be the main factor contributing to calcium uptake. By contrast, drinking was reduced by a decrease in salinity/osmolarity but was little affected by external [Ca2+]. Calculations of the maximum contribution from drinking-associated calcium uptake showed that it became almost insignificant (less than 10%) through a strong decrease in drinking rate at low salinities (0-8 per thousand ). Diluted seawater enriched in calcium to the concentration present in full-strength seawater (i.e. constant calcium, decreasing salinity) restored intestinal calcium uptake to normal. Extra-intestinal calcium uptake also benefited from calcium addition but to a lesser extent.
Guerreiro
Pedro M
PM
Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
Fuentes
Juan
J
Flik
Gert
G
Rotllant
Josep
J
Power
Deborah M
DM
Canario
Adelino V M
AV
D000064:Acclimatization / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000493:pharmacokinetics*; D004326:Drinking; D005618:Fresh Water; D007814:Larva / Q000502:physiology; D021541:Sea Bream / Q000502:physiology*; D012623:Seawater / Q000032:analysis*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D002118:Calcium