CELLULOSE DIGESTION AND METABOLISM IN THE FRESH-WATER AMPHIPOD GAMMARUS-PSEUDOLIMNAEUS BOUSFIELD

1. Weight-specific respiration and feeding rates of Gammarus pseudolimnaeus were inversely related to body weight at 12-degrees-C, the temperature of the stream from which they were collected. 2. At this temperature animals could digest about a third of ingested, purified C-14-cellulose. In animals greater than 20 mg live weight, about 38% of ingested cellulose was metabolized; animals smaller than 20 mg metabolized about 28%. 3. Respired CO2 from cellulose metabolism was 33-47% of measured uptake of O2 in animals greater than 20 mg live weight and approximately 25% in smaller animals. 4. Ability to digest cellulose would be of nutritional benefit to Gammarus feeding on any plant material, but would be of particular advantage in the spring/summer period when fine detritus is the main foodstuff.