Oxygen consumption in two aquatic coleoptera species: Hydrous piceus and Dytiscus marginalis

Abstract The respiratory activity in adults of two species of aquatic Coleoptera, Hydrous piceus and Dytiscus marginalis, was examined to assess the physiological responses of the oxygen content variations of their air stores, called physical gills. The respiration rates were measured at two temperature ranges between 19° C and 30° C by means of a dissolved oxygen metre. The two species showed no significant differences in oxygen consumption, but water temperature affected oxygen gains in the bubbles. The effect of body weight on respiration level did not differ significantly within the two temperature ranges in either species because of the similar weights among individuals. The oxygen exchange between the physical gills and the surrounding water can be used as a measure of the respiratory metabolism of these insects and of their interactions with the surrounding environment.