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1997-1998 RESEARCH CRUISES SCHEDULE TROPICS97 Leg 1 (8-23 May 1997) Physical Oceanography of the Bismark Sea and Sepik River Estuary. Principal investigator : Dr. George Cresswell, CSIRO Division of Oceanography, Chief Scientist OBJECTIVE The main goal of the cruise will be to make a 3-dimensional map of the currents and water properties in and around the Sepik River plume. A secondary aim will be to occupy stations along a transect across the continental slope and shelf in to the coast of southern Papua New Guinea. MOORING POSITIONS Two moorings will be deployed at 200 m and 500 m isobaths near the Sepik mouth. The first of these will be recovered at the end of the cruise, its data downloaded and redeployed. Both moorings will be recovered by an AIMS vessel after one year (1998). Three sediment traps from AIMS will be also deployed.
TROPICS97 Leg 2 (24 May-11 June 1997) Principal investigator: Dr K. Woolfe SCIENTIFIC OBJECTIVE To understand mechanisms and establish models of coastal ocean trapping, bypassing, and cycling of solutes and sediments from wet tropical rivers draining the high relief areas of Papua New Guinea into very different coastal shelves. We hope to determine the processes that control the dispersal of wet tropical riverine dissolved and particulate material into the coastal ocean, and how these processes affect estuarine, deltaic, coastal, shelf, and slope productivity, marine resources, & sustainable development options. CRUISE OBJECTIVES
TROPICS 97 Leg 3 (17 July-4 August 1997) Gulf of Papua - Chemical and Biological Oceanography Principal Investigator : Mr Ron Szymczak OBJECTIVES The specific objective of this cruise is to determine the fate of riverine material entering the Gulf of Papua from the Fly & Purari Rivers and to the Bismarck Sea from the Sepik River. That is, to determine to what extent this material (a) is trapped on the inner-shelf via elemental scavenging processes in the water column, (b) chemically transformed via chemical and/or biological mediation, and/or (c) bypasses the shelf and thus enters the coastal ocean. The study will include both dissolved and particulate forms of nutrient elements (N, P, Si), trace elements (heavy metals, radionuclides, rare earth elements, noble metals) and organic matter (hydrocarbons, PAH's). Special emphasis will be placed on several specific components (iron, manganese, carbon, sulfur, hydrocarbons) known to undergo dynamic chemical transformations in the transition from a freshwater to marine environment. To achieve these objectives, studies will be performed in the estuarine, inner and outer shelf zones of the Fly/Purari and Sepik Rivers outflow regions. We will:
TROPICS97 Leg 4 (4-22 August 1997) Principal Investigator: Dr Denis Mackay OBJECTIVES The major objectives of this part of the TROPICS program would be to investigate the supply of nutrients, organics and trace metals to the equatorial region from the Sepik River. This supply depends on a range of physical (river flow, mixing, current regimes), biological (biological uptake, light penetration, grazing) and chemical process (adsorption, desorption, precipitation, chemical transformation) that would necessitate a multidisciplinary approach. One of the objectives of this cruise is to identify organic biomarkers and isotopic signatures that can be used to trace sediment transport from riverine to oceanic regimes. Use of these biomarkers will, as part of the TROPICS studies allow comparisons of sediment deposition in estuarine and non-estuarine systems. Comparisons of labile and non-labile organic material will be useful to assess scavenging effects and how this relates to organic matter signatures in recent sediments, preservation and subsequent diagenetic products. Measurements of biological productivity and phytoplankton biomass will enable us to assess the relative importance of nutrients (including micronutrients such as iron), light and grazing in this region. Sediment traps may be deployed both on the continental shelf and in the open ocean to determine the vertical fluxes of carbon and related elements. We will also measure the disequilibrium between naturally occurring actinides to provide an independent estimate of particle fluxes and to calibrate the collection efficiency of the sediment traps. Some estimates of phytoplankton class abundances will be made by direct counting and these will be compared with estimates of class abundances from HPLC measurements of photosynthetic pigments. A program for calculating these abundances has been developed at the Division of Oceanography.
TROPICS97 Leg 5 (22 August-19 September 1997) Principal Investigator : Dr Gregg Brunskill Leg 5A : Salinity & Particle Gradient Chemistry OBJECTIVES :
Leg 5B : Mangrove, Estuary, and Tidal Creek Sediment Coring OBJECTIVES :
TROPICS98 Leg 6 (20 May-15 June 1998) Principal Investigators : Drs Gregg Brunskill and Peter Isdale Sepik River Estuary/Bismark Sea Leg 6A (24 May-1 June 98) Recover Creswell Moorings/Sediment Coring OBJECTIVES :
TROPICS LEG 6B (10 days in June 1998) Sepik Region Coral Drilling OBJECTIVES :
Additional benefits: We will use the expedition, and its outcomes, to underpin the complementary research of the TROPICS program by providing information which gives a much longer perspective to the sediment core interpretations and the physical oceanographic data from loggers.
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