Proc 5th Intl Coral Reef Congress (Tahiti) (1985), 5, 21-26
Biology, sedimentology and geography of the vast inter-reefal Halimeda meadows within the Great Barrier Reef Province.*
Edward A Drew and Kay M Abel
Australian Institute of Marine Science, PMB No 3, MSO, Townsville,
Queensland 4810, Australia
*Contribution No 289 from the Australian Institute of Marine Science
Abstract
At least 2000 km2 of the seabed of the GBR Province are carpeted with algal vegetation composed almost entirely of Halimeda. These meadows occur principally between 11^50'S and 15^35'S at depths of 20 to 40 m, but smaller areas also occur in much deeper water (100 m or more) further south. This vegetation is composed mainly of the sprawling lithophytic species normally found on the reefs with the GBR. Biomass of up to 4 kg dry weight/m2 Halimeda (90% calcium carbonate) have been found and the meadows grow upon a coarse gravel composed of dead segments from the local vegetation. The meadows are confined to the outer part of the continental shelf, usually inshore from the outer barrier reefs, and may be supported by upwellings of nutrient-rich, deeper water from the Coral Sea.