Heat production inLittorina saxatilis Olivi andLittorina neritoides L. (gastropoda: Prosobranchia) during an experimental exposure to air

Abstract

The adaptation of littorinid molluscs to prolonged aerial exposure was investigated by the determination of heat production. I_ittorina saxatilis, inhabiting the upper euhttoral, reached a maximum metabolic activity during submersion (heat production: 3.26x 10-3J S-l(gadw) -1. On the first three days of desiccation, the heat production was continuously reduced to 40% of the submersed value. A prolonged aerial exposure was lethal for this species. In the supralittoral L.neritoides, three stages of energy metabohsm could be observed: an intermediate heat production during submersion {1.97 x I0-3j s-l{gaaw)-1), an increased metabohsm during the first hour of aerial exposure (heat production 204 % of submersed value), and a minimal metabolism (39% of the submersed value and 19 % of maximum value) during the following days and weeks of desiccation.Recovery depended on water salinity; L. saxatilis proved to be less euryhaline than L. neritoides.Thus, the metabolic adaptations correlate with the level of littoral habitat; inactivity combined with a drastically reduced energy consumption is a metabolically economic way to survive in periodically dry environments.

Physiological adaptations to high intertidal life involve improved water conservation abilities and metabolic rate depression in Littorina saxatilis

“…Some authors suggest that aerobic metabolism dominates during air exposure in high intertidal animals (Houlihan 1979, Yipp et al 1986, Simpendörfer et al 1995, while others argue that aerobic metabolism in air is most important for low-and mid-shore animals, whereas high-shore invertebrates may rely more heavily on anaerobiosis during air exposure (Kronberg 1990, McMahon 1990. Until now there have been very few attempts to quantify the relative contribution of aerobic and anaerobic metabolism in supplying energy during air exposure in intertidal invertebrates (Shick et al 1983(Shick et al , 1986.…”