Sponge population surveys were conducted in mid-winter (July 1983) at 8 sites along a 1.3 km transect across the reef flat, north of the weather station on Flinders Cay. All sponges within duplicate 2 x 2 m quadrats were collected, identified and weighed (wet weight).
Respirometry was used to measure rates of oxygen exchange on 20 to 55 g (wet weight) samples of sponge tissue. Rates were measured for 5 specimens of each of Carteriospongia "folpap", Carteriospongia "cups" and Phyllospongia "fingers" and 2 specimens of Thorectidae "firmred". Integrated daily productivity was estimated by using light profiles, measured at the time and interpreted using published equations. Summer productivity rates were estimated using the July production and respiration rates and summer light profiles, with no provision for changes in photoadaptation or temperature. Chlorophyll a content (µg/g wet weight) and mean thickness (mm) of the sponge tissue used for respirometry were also measured.