Effects of prolonged starvation on body mass and respiratory physiology of the New Zealand abalone or pāua, Haliotis iris

Context Subtidal, adult pāua experience irregular food supply. The effects of prolonged starvation have not been examined. Aim To examine effects of 105-day starvation on body mass, respiration and haemolymph proteins. Methods Pāua, maintained at 15°C, were divided into groups that were either fed Macrocystis pyrifera, or starved; each group was further divided between pāua whose haemolymph was sampled at intervals and those sampled only at the beginning and end of the experimental period. Body mass, condition, oxygen uptake and gonad index were measured at the start and end. Key results Total mass of both fed and starved groups did not change significantly. The condition of the starved individuals decreased significantly. Haemocyanin accounts almost entirely for haemolymph proteins. The haemolymph haemocyanin concentration in fed abalone fell by 17–27% over 105 days, and by 49–63% in starved individuals. Final normoxic oxygen uptake was similar in starved and fed pāua and declined similarly during hypoxia. Conclusions Pāua may survive extended periods of starvation by metabolising body tissues and haemocyanin, with only minor changes in their mass, condition and aerobic respiration. Implications These primitive gastropods have mechanisms to survive stressors associated with low food availability. Maintenance of body volume in this osmoconformer supports gill perfusion and the functioning of the hydraulic skeleton in locomotion.