Weather records in corals from northern Australia (CCEP Project)

A large scale coral core drilling program was undertaken between March 1986 and April 1987. Coral cores were collected from Porites spp. bommies on reefs between Darwin and Gladstone during four field trips.Cores were drilled using a purpose built coring rig operated by divers on SCUBA. The objective was to obtain long unbroken cores, drilled close to the growth axis of the colony, which had little damage from boring organisms. Cores were collected from bommies at the following locations: Nightcliff (Darwin); Coral Bay (Port Essington); off the mouths of the Jeannie and Pascoe Rivers and Burkitt Island (Cape York); Stanley Reef (Cape Upstart); Scawfell Island (south of the Whitsunday Islands); and Masthead Island (Capricorn Bunker Group).A computer-controlled fluoromicrodensitometer (Fluorac) was constructed to simultaneously record density and fluorescence of cores and analyse these data. An image-processing system was acquired to attempt to develop a standardised technique for rapid retrieval of fluorescent band proxy records from coral cores.Water samples were collected from the rivers nearest the bommies drilled in the vicinity of Cape York. Soil and river samples were also collected from various locations in the Fitzroy catchment area. These samples were analysed to identify any humic and fulvic acid compounds present. This project was initiated to collect long cores from Porites spp. bommies, from a wide range of locations, with the aim of establishing proxy rainfall figures for tropical Australia. The fluorescent bands in nearshore corals consist of terrestrial humic and fulvic acid compounds and the bands have been proven to be closely correlated with runoff from nearby river systems. Proxy data in corals could be invaluable in a variety of fields, including meteorology, climatology, agriculture and coastal engineering.A secondary component of this project was to trace the terrestrial components in the yellow-green fluorescent bands back to their sources to allow estimation of the contributions made by different rivers and to enable more precise estimates of zonal rainfall.