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Equilibrio ácido-base durante la exposición aérea en el molusco bivalvo Perumytilus purpuratus (Lamarck, 1819) (Bivalvia: Mytilidae)

2009; University of Valparaíso; Volume: 44; Issue: 1 Linguagem: Inglês

10.4067/s0718-19572009000100018

0718-1957

Luis A. Montecinos, José A. Cisterna, Cristian W. Cáceres, Gonzalo S. Saldías,

Marine Bivalve and Aquaculture Studies

For effects of tidal rhythms, intertidal bivalves are exposed to prolonged daily emersion periods during low tide.As a response to air exposure, the mussel Perumytilus purpuratus (Lamarck, 1819) closes its valves and shifts its metabolism to anaerobic pathways by the interruption of the oxygen flux.Consequently, body fluids low their pH causing the CaCO 3 disolution of the shell, which would act as a pH buffer.In this study, the role of shell CaCO 3 in the regulation of internal homeostasis at different periods of aerial exposure was evaluated.We measured the variation of pH, Ca 2+ and HCO 3 -concentrations in the extrapallial cavity and Ca2 + concentration at the shell of P. purpuratus individuals from the low and high intertidal zones.The results show that pH increases in the extrapallial cavity fluids during the emersion period in the laboratory, followed by a decrease of the shell Ca 2+ .Ca 2+ and HCO 3 -concentrations did not show a significant variation in extrapallial fluids during the aerial exposure periods.Moreover, significant differences were found in the Ca 2+ and HCO 3 -concentrations at the extrapallial fluids between individuals from low and high tidal levels.However, in the majority of measured variables, in spite of acclimation period, the basal levels were different between individuals from the low and high intertidal zones, suggesting physiological differences due to genetic differences among organisms inhabiting both zones.