Resumen

LAGOS, Marcelo E  y  CACERES, Cristian W. Effect of aerial exposure in acid-base equilibrium in intertidal mobile organisms: Petrolisthes laevigatus (Guérin, 1835) (Decapoda: Porcellanidae) as study case. Rev. biol. mar. oceanogr. [online]. 2008, vol.43, n.3, pp. 591-598. ISSN 0718-1957.  doi: 10.4067/S0718-19572008000300018.

Due to the action of tidal rhythms, intertidal animals can spend 50% of their lives exposed to aerial conditions, which produces highly specific physiological responses (e.g. high tolerance to desiccation, development of alternative pathways of oxygen uptake). Such responses have mostly been studied in sessile species. In this article, we studied physiological responses in the concentrations of calcium and CO₂ partial pressure in the hemolymph of the intertidal crab Petrolisthes laevigatus. We experimentally exposed individuals of this species to variations in aerial exposure (0, 6, 15, 60, 120, 240 and 360 min). Changes in pH, concentrations of calcium (Ca²⁺) in the hemolymph and exoskeleton, bicarbonate ion (HCO₃) and the partial pressure of CO2 in the hemolymph were evaluated. The results show a reduction of exoskeleton calcium [Ca²⁺] and an increase in hemolymphatic calcium [Ca²⁺] concentrations with increasing aerial exposition. These results could indicate the dissolution of exoskeleton CaCO₃, suggesting a regulation of the acid-base balance during aerial exposure. The lowest pH and the highest HCO₃- and PCO₂ concentrations were found in the group with 0 minutes of aerial exposure (i.e. submerged conditions). This results would indicate a respiratory alkalosis response during emersion periods, which results in reduced breathing capacity during periods of immersion.

Palabras clave : Crab; homeostasis; physiological adaptation; respiration.