REEF FORAMINIFERA AS BIOINDICATORS: A COMPARISON BETWEEN LOW ISLES AND HERON ISLAND REEFS, GREAT BARRIER REEF, AUSTRALIA

Low Isles and Heron Island Reefs are two coral reef platforms in the Great Barrier Reef in northeast Australia. Low Isles, located in the northern part of the Great Barrier Reef, is developed on an area of the shelf dominated by terrigenous mud and lies within the reach of river flood plumes. Heron Island, situated near the southern reaches of the Great Barrier Reef, is developed on the outer shelf where sediments are dominated by calcium carbonate. The differences in reef setting provide an excellent opportunity to study how terrigenous input, which may contain fertilizers, may distress coral communities. Such effects are here investigated through a comparative study the benthic foraminiferal assemblages of both reefs. Reef-dwelling foraminifera of the Caribbean and Atlantic have been shown to be good proxies for coral growth because many contain endosymbionts similar to coral and require the same environmental conditions to flourish. We examine the applicability of this proxy for Pacific reefs. Statistical methods, originally developed for the Caribbean, are applied to the examination of foraminifera species on Heron and Low Isles reefs to determine which of the two reefs is more suitable for coral growth. It is expected that Low Isles Reef should show signs in foraminiferal assemblages that suggest that the environment is stressful to corals, while results from Heron Reef should show the opposite. This result would imply that runoff from agricultural activities on the mainland may be adversely affecting coral growth in nearshore areas.