Water column and sediment processes in the Fly River delta and Gulf of Papua, Papua New Guinea

In July-August 1989 (from sites D1- D7) and February 1990 (from sites D1- D10 in the delta, and GP1-GP8 in the gulf) samples were taken to determine standing stocks of dissolved nutrients (ammonia, nitrate, phosphate, silicate), chlorophyll a, total suspended load, microparticulate organic carbon and nitrogen, bacteria and zooplankton. Of the 107 taxa, adult copepods were identified to species level while other taxa were grouped at higher taxonomic levels. Three replicate samples were taken of surface and bottom water where depth <10m; in deeper water, samples were also taken at intermediate depths - depth, salinity, temperature, Secchi disc depths and tidal period were recorded. Floating macroparticulate matter (leaves, sticks, seeds, etc.), and associated neuston (surface dwelling fauna), was sampled. Plant material was dried, weighed and subsamples analysed for carbon and nitrogen and the mean C:N ratio calculated. Primary production was estimated by 14C uptake. Oxygen consumption (community metabolism) and bacterial production were measured.

Fourteen of the sites from 1989 and 1990 (D1, D2, D4, D5, D7, D9, D10, GP1, GP3, GP4, GP5, GP6, GP7, GP8) were analysed for particulate copper in sediments, porewaters and bottom waters. Dissolved copper fluxes across the sediment-water interface were measured.

In September-October 1991 and January 1993, surface waters of the Fly Delta and Gulf of Papua were sampled (D2, D3, D4, D6, D7, D9, D15, 1GP1, 1GP2, 1GP3, 1GP8, MGP1, MPG2, OGP1, OGP2, plus another 16 [numbered] stations in the Fly delta). CTD casts for salinity and temperature profiles were taken. Nutrient analyses were performed, chlorophyll a concentrations analysed and bacterial densities and production estimated. Primary production was estimated by 14C uptake. Total suspended solids, particulate carbon, nitrogen, phosphorus, and the C:N ratio were measured. Dissolved organic carbon, silicate, phosphate, ammonia and nitrate, and dissolved inorganic nitrogen and phosphorus were measured.