Influence of temperature, size and sex on aerial respiration of Pomacea canaliculata (Gastropoda: Ampullariidae)

SEUFFERT, MARÍA EMILIA; MARTÍN, PABLO RAFAEL

MALACOLOGIA

INST MALACOL

Lugar: Michigan; Año: 2009 vol. 51 p. 191 - 200

0076-2997

Pomacea canaliculata is a freshwater Neotropical gastropod that has both a gill and a lung. During aerial respiration pumping movements of the cephalopodium lead to lung ventilation through an extensible siphon in contact with the water surface. Laboratory trials were performed to investigate the effect of temperature, size and sex on lung ventilation frequency, duration of each pumping movement and number of pumping movements. Lung ventilation frequency increases significantly with temperature and this may be due to an increase in basal metabolic rate and a decrease in dissolved oxygen. Lung ventilation frequency also showed a positive relationship to snail size, probably related to a decrease in the gas exchange surface relative to body mass. The duration of each pumping movement decreased asymptotically with temperature, suggesting that the velocity of muscular contraction is the limiting factor in the response of this variable. The number of pumping movements showed no response to temperature but increased with size within sexually differentiated snails, probably due to an increase in the respiratory dead space, since the lung is a simple sac and siphon length increases with snail size. None of the aerial respiration variables investigated showed differences between sexes. Snail depth during lung ventilation increases markedly beyond a shell length of 20 mm. Lung ventilation begins within three hours of hatching and is performed routinely as long as the snails are active even in oxygen saturated waters. However, the mechanism and degree of air dependence in P. canaliculata need to be clarified to reach a better comprehension of the effects of lung ventilation on distribution at different spatial scales and on daily time allocation.