Cellulase activity of leaf litter and stream-dwelling, shredder macroinvertebrates

The magnitude and temporal variability of exocellulase ( beta -1,4-exoglucanase) activity in leaf litter and guts of shredding macroinvertebrates was determined over one year in four streams in Virginia, USA. The streams flowed in three physiographic provinces and hence varied as to geomorphology, hydrology, water chemistry and riparian landscape. No significant difference in exocellulase activity occurred between streams over the year. Considerable temporal variation in activity did occur in all streams, with peaks in autumn-early winter and again in spring, corresponding to the primary periods of input of fresh allochthonous organic matter. Litter bag studies showed that peak exocellulase activity occurred after about one month of processing. Exocellulase activity in the guts of shredders was generally correlated with activity in their detrital food, suggesting that gut enzyme activity was acquired.