A calibration that predicts Secchi depth, chlorophyll a and suspended
solids from this indicator system for GBR inshore reefs is
presented in Table 4. This analysis combines the data from all 20
reefs from the two studies. Nine of the indicators were strongly
correlated to Secchi depth (Fig. 5), while four other indicators
(esp. the coral juvenile indicators and crustose coralline algae)
were strongly related to chlorophyll, and a total of nine indicators
were strongly related to total suspended solids (Table 4). For example,
an increase of 1 unit in the FORAM index represented a 1.8 m
increase in Secchi depth, while a decline in the FORAM index by 1
unit represented an increase in chlorophyll by 1.4 lg L1 or in total
suspended solids by 2.9 mg L1
. Equally, a 10% decline in macroalgal
cover represented a 4.4 m increase in Secchi depth, a decline in
chlorophyll by 1.6 lg L1 or in total suspended solids by
3.4 mg L1
. Estimates can be improved and confidence intervals
derived by averaging the estimates from multiple bioindicators.