Biological and chemical oceanographic measurements from Western Australia and Northern Territory shelf waters

An extensive series of hydrographic and biological oceanographic measurements were made on the transit legs of the RV Lady Basten in July-August 1993 and October-November 1993 in North Western Australia. The westward route proceeded across the Timor Sea from Darwin to Scott Reef and after a series of biological oceanographic measurements and oceanographic instrument deployments at that site, to Dampier. On the return voyage, the scientific party aboard the Lady Basten made further biological measurements at sites near Scott Reef, then carried out an extensive program of water sampling along the Kimberley coast before proceeding east across the Timor Sea to Darwin.

In all, 68 hydrographic stations were sampled in the Timor Sea and on the North West Shelf. Water column primary production measurements were made at 16 of these stations and bacterial production measurements at 16 stations.

Measurements made at sampling stations along the transit route included:

1. Water column temperature, salinity and density structure
2. Dissolved and particulate nutrient (N, P, Si) concentrations
3. Phytoplankton biomass and community size structure
4. Zooplankton standing crop and composition
5. Water column primary production
6. Water column bacteria numbers and biomass (westward leg only)
7. Water column bacterial production (westward leg only)
8. Trichodesmium abundance and distribution
9. N fixation by Trichodesmium (eastward leg only)