Water was sampled at three stations located between Port Douglas and Undine Reef and at a single station on the leeward side of Agincourt Reef twice before Cyclone Sadie (January 11 and 18, 1994) and twice after Cyclone Sadie (February 1 and 3, 1994).
Water samples were collected with a water bottle from the sea surface and near the bottom at each of these four stations. Salinity was immediately determined using a YSI conductivity meter. Duplicate 10 ml subsamples were collected from each bottle, filtered with disposable syringe filters and stored frozen for later analyses of nitrate and phosphate using a multichannel segmented flow autoanalyzer.
Observations of the Daintree River plume were made following a further period of heavy rainfall, which occurred from the 18-20 February, 1994. A series of hydrographic measurements were conducted at eleven stations between Cape Tribulation and Port Douglas on February 21 and 22. At 4 stations close to the mouth of the Daintree River, water samples were collected from two to four different depths using Niskin bottles. Duplicate 10 ml subsamples were obtained, processed as described above, and analysed for dissolved inorganic and organic nitrogen. A 100 ml subsample was also obtained from each bottle, filtered onto a Whatman GF/F glass fibre filter, stored frozen and analysed for chlorophyll by fluorometry.