Field measurements of ingestion and assimilation for the Australian brine shrimp Parartemia zietziana Sayce (Crustacea: Anostraca)

Abstract

AbstractIngestion and assimilation of the brine shrimp Parartemia zietziana were measured in the field. Populations in Pink Lake and Lake Cundare were used; both lakes are shallow (< 1 m), saline (> 60°/00), and located in western Victoria; they have tow primary production. P. zietziana relies largely on organic matter in lake sediment for food. Ingestion rate was measured in situ in Pink by following the uptake of 14C from labelled sediment. The rate of faecal pellet production was measured (in both lakes) by allowing animals to defaecate for 24 h in a net suspended in the lake. Ingestion rate varied from 0.35 to 13 01 × 10–1 mg dry wt h‐1 individual‐1 for a range in dry weight of shrimp from 0.2 to 2.3 mg individual‐1; for a similar range in weight, defaecation varied from 0.08 to 2.03 × 10‐1mg dry wt h‐1 individual‐1. These rates were converted to joules and assimilation efficiencies of 30–60% calculated. Regressions showed that change in dry weight of shrimp accounted for > 90% of the variance in both rates.