The sum of carbohydrate, protein, and lipid carbon was reported as the labile carbon fraction (LOC), assumed to be the fraction of total OM potentially available to consumers. The ratio of each carbon pool (i.e., PRT, CHO, and LIP) to total labile organic carbon was calculated for each sediment type. Sediments treated in a muffle furnace (550 °C,6 h) were used as blanks for each chemical analysis.