Annual Biodeposition and Gross Energy Budget of Mature Pacific Oysters, Crassostrea gigas

Abstract

The mean annual volume of seawater pumped by Pacific oysters in Departure Bay, British Columbia is 1488 liters/g per year. The energy requirement for metabolism and pumping is 1.74 cal/liter, while the mean annual caloric content of the seawater is 60.4 cals/liter. Annual biodeposition is 8.9 g/g per year; these data applied to a mean biomass of 190 g/m2 for a mature oyster reef show that 22,052 kcal are theoretically available for ingestion, but only 11% are retained, mostly to be biodeposited. The biodeposits have a caloric value of 1545 kcal/m2 and furnish an important nutritional substrate. Another important contribution to the food web is the annual release of gametes, equivalent to 502 kcal/m2 reef.