Decomposition processes in mangrove mud in the Fly River estuary, Papua New Guinea

Microbial productivity, nutrient chemistry and rates of nutrient regeneration were examined in muds of different mangrove forests in the Fly Delta, Papua New Guinea.Three forest types Rhizophora-Bruguiera, Nypa and Avicennia-Sonneratia with high and low intertidal stations in each forest type.Sedimentary variables were: temperature; grain size; salinity; porosity; and percent sand, silt and clay.Microbial samples were measured for chlorophyll a, phaeopigments and bacterial numbers. Bacterial production rates were measured by two procedures: the rate of [3H]methyl thymidine ( = Tdr) incorporation into DNA and by the rate of [3,4,5-3H] leucine (L = Leu) incorporation into protein.Dissolved nutrient (DOC, DON, DOP, ammonium, nitrite, nitrate and phosphate, silicate) flux measurements and primary production (O2 flux) were made for each site.Cores were taken for measurements of solid-phase elements and porewater nutrients at each site. To examine microbial productivity, nutrient chemistry and rates of nutrient regeneration in muds of mangrove forests. This research project was a component of a larger project to determine the influence of freshwater and detrital export from the Fly River system on adjacent pelagic and benthic systems.