The responses of three species of bivalve mollusc to declining oxygen tension at reduced salinity

Abstract 1. 1. Geloina ceylonica and Anadara granosa experience hypoxic conditions and can regulate their oxygen consumption at reduced oxygen tension in water of full sanity. 2. 2. These two species, and Mytilus edulis , can also regulate oxygen consumption at reduced oxygen tension in diluted sea water. Their capacity to regulate is reduced under these conditions, although only in Anadara is this reduction very marked. 3. 3. At reduced salinity, oxygen consumption by Mytilus is inhibited at first, but recovers within 48 hr. The ability to regulate oxygen uptake at reduced oxygen tension is not lost during the acclimation period. 4. 4. At 23·5% 0 S perfusion index increases with reduced P O 2 , but at 16·3% 0 S perfusion index does not change as P O 2 is reduced to 60 mm Hg.