CLIMATE VARIATION AND EL-NINO SOUTHERN OSCILLATION EVENTS ON THE GREAT-BARRIER-REEF - 1958 TO 1987

Seasonal and inter-annual variation of several surface climate variables near the Great Barrier Reef (GBR) are described for the 30-year period, 1958-1987. Large inter-annual variability of rainfall and river flow in coastal Queensland is linked to the aperiodic influences of El Nino-Southern Oscillation events. These events also affect sea surface temperature and wind fields, though the inter-annual variability of these variables is not as large as rainfall and river flow. The major impacts on waters of the GBR appear to be greatly increased freshwater inputs, reduced surface radiation (and thus light levels) and enhanced tropical cyclone activity during anti-El Nino events. El Nino events have less effect on climate of the GBR because they tend to maintain winter-like conditions. The effects of this background of high variability in the physical environment on reef processes must be considered when examining changes in such processes, changes in climate (e.g. due to global warming) or increases in anthropogenic impacts.