Coral calcification in massive Porites in the nearshore region of the northern Great Barrier Reef

Brief description

Ten massive Porites colonies were collected from the fringing reefs of each of 4 inshore islands of the Great Barrier Reef in January 2004. Two reefs were located in the Far Northern Region (Hannah Island and Hay Islands) and two reefs were located approximately 450 km away in the Northern Region (High Islands and Kent Islands). All colonies were >=30 cm in diameter and were selected from the leeward side of each island at depths between 1 and 3 m below the lowest astronomical tide. Of the 40 colonies collected, 38 colonies were found to be suitable for the analysis of growth parameters.A slice, approximately 7mm thick, was cut from the centre of each colony, dried and X-rayed. The positive X-ray prints were used to identify two tracks on each slice with clear annual density bands and also to date these bands. Skeletal density was measured at 0.25 mm intervals along each track using a gamma densitometer. From these measurements, spatial and temporal variations in three annual coral growth parameters; annual extension (linear distance between adjacent density minima (cm/y)), skeletal density (g/cm³) and calcification rate (the product of skeletal density and annual extension, g/cm²/y) were calculated. The three variables were then averaged across the two densitometer tracks for each corresponding growth year.While the age of annual growth bands ranged from 1971 to 2003, few bands were recorded before 1988 and analysis was focused on the period 1988-2003. Average monthly SST for each region were obtained from the HadISST 1.1 database, available from the British Atmospheric Data Centre. This study was carried out to examine temporal and spatial variation in growth parameters of massive Porites corals from two inshore regions of the Great Barrier Reef. The relationship between growth parameters and sea surface temperature (SST) was also investigated.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Statement: The procedures used to determine growth parameters are described in:Barnes DJ and Lough JM (1989) The nature of skeletal density banding in scleractinian corals: fine banding and seasonal patterns. Journal of Experimental Marine Biology and Ecology 126: 119-134.Chalker BE and Barnes DJ (1990) Gamma densitometry for the measurement of skeletal density. Coral Reefs 9: 11-23.Lough JM and Barnes DJ (1990a) Intra-annual timing of density band formation of Porites coral from the central Great Barrier Reef. Journal of Experimental Marine Biology and Ecology 135: 35-57.Lough JM and Barnes DJ (1990b) Measurement of density in slices of coral skeleton: effect of densitometer beam diameter. Journal of Experimental Marine Biology and Ecology 143: 91-99.

Notes

Credit
Cooper, Timothy F, Dr (Principal Investigator)

Credit
Lough, Janice M, Dr (Custodian)