JOHN BREWER

This reef has been surveyed extensively since 1984. Initially John Brewer Reef was subject to extremely high COTS populations and the reef was classified as an Active Outbreak. COTS populations subsequently declined and the reef was reclassified as Recovering in 1986. Median reef-wide live coral cover remained low (1-10%) through to 1990 before beginning to increase. Surveys in 1993 showed reef-wide live coral cover had increased to moderate (10-30%) levels and by 1998 overall coral cover peaked at high (30-50%) levels.Surveys in 2001 indicated COTS numbers had begun to increase and the reef was reclassified as Active Outbreak. COTS have remained at outbreak levels since this time and there has been a corresponding drop in coral cover to the current very low (1-5%) levels. COTS numbers remain high and John Brewer Reef is currently classified as Active Outbreak. White Syndrome Disease and coral bleaching were recorded from a small number of scattered coral colonies during surveys in 2003.

Detailed coral surveys since 1993 show that hard coral cover reached a maximum of 32% in 1996 then, with the impact of Cyclone Justin, declined slightly in 1997. A low level of coral bleaching was recorded in 1998 and 1999. Between the years 1999 and 2000 cover of hard coral decreased by 8% and cover of hard corals averaged 21% in 2000. This most recent decline was probably caused by increased COTS activity on this reef. Tabulate Acropora has remained the dominant hard coral throughout the survey period and changes in cover of hard coral have been largely driven by changes of abundance in this dyamic coral. Cover of soft corals also declined from 6% in 1995 to 2% in 2000. Only two taxa (Amblyglypdidodon and Chromis) showed positve trends over the last six years, in both cases the increasing trends were due to single abundant species. Amblyglphidodon curacao increased in abundance to 1997 then remained relatively stable whereas Chromis atripectoralis has increased steadily over the period of survey. Many of the declining taxa show a similar profile in which species driving the trends showed peaks in abundance in the 1995-97 period before steep declines to 2000. For Pomacentrus this pattern was evident in P. lepidogenys, P. moluccensis and P. coelestis with P. wardi showing a general decline over the period of survey. For Neopomacentrus, N. azysron peaked in 1995 and has declined to approximately one fifth of the 1995 high. For Chrysitera, C. rollandi and C. talbotti both peaked in abundance in 1996 from which point they have steadily declined. Likewise Acanthuridae, driven by Ctenochaetus spp. peaked in 1995-96 before declining to the current low abundance. The observed decline in Labridae is not evident in any species in particular.

John Brewer (No. 18-075) is a middle shelf lagoonal reef with an area of 17.5 sq.km. Last surveyed March 2003.







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