Metabolic processes at Lizard Island, Great Barrier Reef (LIMER Expedition, 1975)

Chemical cycling and energetics of the coral reef system at Lizard Island, North Queensland were studied during September-October 1975 by the LIMER (Lizard Island Metabolic Exchange on Reefs) expedition, a cooperative investigation by 8 institutions. Calcification, primary production, the nitrogen cycle, the sulphur cycle, zooplankton distribution, and water currents of the reef system were investigated.

Patterns of water movement at ebb and flood tides was measured using Woodhead current drogues deployed 10 cm below the surface.

Calcification activity rates were based on the alkalinity-anomaly approach; areas measured were the algal crest on the seaward reef flat, a large pinnacle at the entrance channel to the lagoon, a transect across the central-leeward reef flat, a sandy algal bottom with small coral heads, and a sandy reef flat with extensive algal filming. Replicate samples of a foraminifera (Marginopora vertebralis), a common coral (Acropora), crustose and foliate algae (Lithothamnian and Halimeda spp.) were also measured experimentally in a laboratory for their rates of calcification.

Sulphate reduction and ammonia accumulation rates in reef and lagoon sediments were assessed.

The nitrogen cycle was investigated using in situ and experimental measurements. Concentrations of nitrate on the algal crest, the lagoonal reef flat and oceanic front of the reef were measured and rates of nitrate exportation into the lagoon calculated. Nitrogen fixation was measured using the C2H2 assay technique.

Primary production was estimated using measurements taken along a transect from the windward edge of the reef to the lagoon. Light attenuation was measured in the lagoon and in the ocean in front of the entrance.

Zooplantkon were sampled during the day and at night, in the water column at different depths, and from reef and lagoonal sediments. Both micro and macro-zooplankers (amphipods, cumaceans, large copepods, polychaetes, shrimp and fish larvae) were measured from 6 stations.