The brown mussel Perna perna on the Natal coast, South Africa: utilization of available food and energy budget

Abstract

The filtration rate of P. perna (L.) at the approximate annual mean local water temperature (20.degree. C) is high, being 2.7 .times. 10-3 (shell length in mm)1.86 l h-1 or 8.85 (dry flesh weight in g)0.66 l h-1. It was able to filter latex particles down to at least 0.46 .mu.m in diameter, these being roughly the mean size of free coccoid bacteria in the study area. Its mean assimilation efficiency, determined by the Conover method, was 61% on a natural diet of particles < 100 .mu.m in diameter which had a mean organic content of 3.16 mg l-1. The feces production rate is also established and an energy budget for P. perna is discussed in the light of available data.