DECOMPOSITION OF WATER HYACINTH DETRITUS IN EUTROPHIC LAKE WATER

A study was conducted to determine the seasonal production of detritus by water hyacinths [Eichhornia crassipes (Mart.) Solms] cultured in eutrophic Lake Apopka water, and the decomposition of detritus in situ and under laboratory conditions. Annual averages for C, N and P deposited through detritus production at the sediment-water interface were 2870, 176 and 19 kg ha-1 yr-1, respectively. Decomposition rates were faster in the root zone of hyacinth mats than at the sediment-water interface. Approximately 92% of the detritus C deposited at the sediment-water interface was decomposed in one year, while only 11% of the detrital organic N was mineralized. Detrital tissue gained P during decomposition, suggesting P limitation for the system. Dry-weight loss of detrital tissue was significantly correlated with the mass of C lost (r2 = 0.947**), C/N ratio (r2 = 0.644**) and C/P ratio (r2 = 0.428**).