The dry mass of reed mesh bags was monitored daily for 40 days at two sites in an Italian lagoon. The original daily-collected data set was manipulated by increasing inter-sampling time intervals to assess the effect of varying the sampling lag on the detection of inter-sites differences in decomposition patterns. At daily intervals, differences between sites were significant, although non-random, short-term mass fluctuations were observed. However, for linear interval increments, there were no between-site differences for lags ≥7 days; in addition, for geometrical interval increments significant differences were never observed. Our study suggests that the temporal resolution chosen for a decomposition study may affect the detection of inter-site differences, emphasizing a previously-unexplored time dependency for leaf detritus decay patterns