Figure 5
From: Impacts of light limitation on corals and crustose coralline algae
Water quality conditions before and during a large-scale, capital dredging project on the coral reefs surrounding Barrow Island (north-west Australia) where ~7.6 M m3 of sediment was removed over a 530 d period (for further details see Jones, et al.23 and Fisher, et al.22). Turbidity (NTU) and benthic PAR levels (DLI, mol photons m−2 d−1) are shown for the extended pre-dredging baseline and dredging phase at one site, located 0.8 km from the primary excavation site at 6.2 m depth. Horizontal coloured ribbons on the right hand quantile plot show the range of calculated DLI thresholds for each of the 3 species and life stages (see Table 2) investigated, including A. millepora, P. acuta and P. acuta juveniles for both 10 and 50% impacts on colour index (EI10 = orange and EI50 = red). Data presented are the daily mean NTU and DLI (black), with 30 d running means (blue solid line). Periods when the 30 d running mean DLI drops below the experimentally calculated threshold values (Table 2) are indicated by the appropriate threshold colour. Quantiles of 30 d running mean DLI are also presented across the pre-dredge (grey) and dredging (black) phases.
