Effects of aerial exposure on oxygen consumption by the New Zealand mussel Perna canaliculus (Gmelin, 1791) from an intertidal habitat

Abstract

Aquatic and aerial oxygen uptake were measured for Perna canaliculus (Gmelin) (length 20–60 mm) collected from mid-tide and low tide levels of a rocky shore during summer and winter. Oxygen uptake increased with tissue dry weight in aquatic and to a lesser extent aerial conditions at most temperatures investigated, 10, 15 and 20°C in summer and 5, 10 and 15°C in winter. Aerial exposure reduced oxygen uptake up to 87% of the aquatic value with greater reduction at higher exposure temperatures. Oxygen uptake was similar in mussels from both shore levels and there was no pronounced increase in the aquatic oxygen consumption of mid-shore individuals. There was little evidence of seasonal adjustment in the aquatic oxygen uptake rate–temperature ( R– T) curve for mussels from either mid- or low-shore levels; generally oxygen uptake increased at higher exposure temperatures. In contrast, oxygen uptake of P. canaliculus in air was generally reduced at higher exposure temperatures, and there was a small seasonal acclimatory response. Calculations of the daily oxygen requirements of mussels from the two shore levels suggest energy savings of 35% for mid-shore mussels during summer due to reduced oxygen demand in aerial conditions at higher temperatures.