Abstract: Changes of caloric values and energy-rich organic compounds were studied in the detritus derived from mangrove Kandelia candel (L.) Druce leaf litter during the various in situ seasonal decomposition in Jiulong River Estuary, Fujian, China. The results showed that the caloric values varied little among the seasonal fallen leaves being a mean of 19.63 kJ/g dry wt or 21.55 kJ/g AF dry wt, the caloric values of detritus increased remarkably after decomposition but they more rapidly in summer and autumn than in winter and spring. The change was well in agreement with the degree of decomposition, being increased in the early decomposition period and slightly decreased in the later, with a peak at about the half-time of decomposition (50% weight loss). The maximum was averagely 17.67% of dry weight and 14.35 % of ash-free dry; weight basis over the initial values. The dissipation of total energy was somewhat slower than the loss of dry matter. As decomposition proceeds the energy of detritus was more and more contributed by raw protein, raw fat, raw fibers rather than by N-free extract. Therefore it is suggested that detritus at half-time of decomposition should be more important to marine detritivores from the viewpoint of energy supplement.

Key words: Mangrove: Kandelia candel, Leaf litter, Decomposition: Detritus: Energy