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The Transformation of Energy by a Stream Detritivore, Pteronarcys Scotti (Plecoptera)

McDiffett, Wayne F.
Ecology 1970 v.51 no.6 pp. 975-988
Pteronarcys, body weight, calorimetry, detritivores, energy conversion, energy metabolism, exoskeleton, feces, leaves, nymphs, photoperiod, respiratory rate, statistical analysis, streams, temperature, trout, Georgia
The bioenergetics of a detritus—feeding stonefly Pteronarcys scotti, were invetigated. The nymphs were collected from a north Georgia trout stream and held under simulated field conditions of temperature and photoperiod in a laboratory stream. Rates of respiration and egestion were measured at temperatures approximating those in the field at the time of collection. An estimate of the growth rate of nymphs was made from a statistical analysis of monthly field samples. Calorimetric determinations were made of nymphs, molted exoskeletons, and feces. A 17—month energy budget for the average nymph was tabulated on the basis of the data collected. Assimilation and growth efficiencies were found to be low with mean values of 10.6%, 34.2%, and 3.6% for assimilation and net and gross growth efficiencies, respectively. An assessment was made of the rate of leaf breakdown by the nymphs, and a value of approximately 29.1% of the dry body weight per day was calculated. The functional importance of the organism to the stream community is discussed.