Decomposition of mangrove leaf litter in Chunda Bay, north Queensland

Ageing yellow leaves, still attached to branches, but ready to abscise were collected from three mangrove species, Rhizophora stylosa, Avicennia marina and Ceriops tagal var. australis in Chunda Bay. Groups of leaves from each species were weighed and sewn into mesh bags of 2 mm² mesh size. Five leaf groups from each species were retained to derive fresh weight:dry weight:ash free dry weight (AFDW) conversion factors. The remaining bags were distributed in the field according to a combination of habitat (fully submerged in creek or mid-intertidal zone of forest) and site (two sites separated by 1 km of mangrove forest). For each species, 3 bags were removed on days 14, 40, 71, 112 and 156 of the study. Only leaves of Rhizophora and Ceriops from forest habitats remained after this time and were collected on day 348.In the laboratory, leaves from each bag, were rinsed, sieved and a subsample taken for analysis of bacterial densities. The remainder was dried, ground and subsamples were used to determine percent ash, percent carbon and nitrogen and percent soluble tannins. This field research was undertaken to:1. determine decay rates of leaf leaf litter due to bacterial action and leaching in the intertidal zone of mangrove forests and in the adjacent subtidal waters2. determine the nutritive value of different types of leaf detritus to consumers. This study is a component of a larger project to measure the inputs to mangrove detrital pools from a range of sources including turnover of litter by shredders and and the breakdown of wood.