UPTAKE OF AMINO ACIDS BY MARINE POLYCHAETES UNDER ANOXIC CONDITIONS

1. The effect of anoxia on influx and net flux of amino acids from dilute solutions into two species of marine polychaetes was studied. 2. Rates of influx and net flux correspond quite closely at ambient concentrations greater than 10 µM. Anoxic conditions, produced by incubating specimens of Marphysa and Pareurythöe in solutions containing 2 mM KCN or through which N₂ was bubbled, did not affect the tight correspondence between influx and net flux, though rates were reduced by approximately 50%. 3. The effect of P_o2 on influx and net flux was examined using a continuous flow system. Influx and net influx remained at control rates down to P_o2' s 10 to 20% of air saturation values. 4. Comparisons of rates of net flux to measured values of O₂ consumption indicate that these animals can acquire sufficient reduced carbon to account for their oxidative needs if their surfaces are exposed to amino acid levels on the order of 50 to 65 µM. 5. Primary amines in the interstitial water of sediments in the immediate vicinity of populations of these worms averaged between 123 and 131 µM. 6. Marphysa and Pareurythöe live in habitats that are relatively rich in amino acids, and they possess transport systems capable of the net accumulation of these compounds at rates sufficient to provide a significant supplement to other forms of feeding. The uptake process continues during periods of anoxia, though its rate and overall contribution to metabolic requirements are reduced.