However, there were considerable differences between Reef Groups, Distances and Seasons. learn more At Group A, at the reef edge (0 m) and during the summer, nearly half of measurements indicated hypoxia (<0 mV). This contrasted markedly with 4 m distance, at the same reef group, where none of the stations were

hypoxic and during winter where the proportion indicating hypoxia/anoxia, at the reef edge, was much lower (23%) ( Table 2, Fig. 2). This trend, of increased hypoxia during summer, and as a function of reef-proximity, was also seen, but of reduced magnitude, at Group B but virtually absent at Group D ( Table 2, Fig. 2). However, at Group D there was a trend of increased proportions of samples that were ‘transition’ (sensu Wildish et al., 2001) as a function of season and reef-proximity ( Table 2, Fig. 2). In close proximity to the reef, redox was highly variable, for example on Group A, during the summer, redox varied between −160 and +190 mV at the reef edge (Fig. 2). In terms of the random effects, within reef groups, there were

differences between modules (Table 3). There was also higher variability in redox during summer months compared with winter months (standard deviation multiplier ranged between 0.50 and 1.3) Metformin order and 1.6 × the variability in redox at 0 m compared with 4 m (see weightings in Table 3). In terms of the modelled fixed effects, mean redox differed between distances but this was influenced by both the reef location and season (Fig. 3). Redox was lower in close proximity to the reef (compare zero and 1 m distance, Fig. 3), and this difference was maximal during the summer, particularly at Group A, with projected means, at the reef-edge, being lower by 40–120 mV (95% CI) (Fig. 3). This affect was still discernible, but of reduced magnitude, at Group B, Protirelin but only during the summer (Fig. 3). At Group D there were negligible differences in mean redox as a function of distance regardless of season (Fig. 3) but, across all Groups and Distances, there was a general trend of redox levels being lower in the summer compared to winter (Fig. 2).

The exception to this seasonal trend occurred during February 2005, at Group A (0 m), where negative redox values were recorded (Fig. 2). The confidence intervals shown in Fig. 3, for distances 1 and 4 m, are entirely overlapping at all combinations of Season and Group and this is interpreted as indicating that the discernible impacts, on redox, of the reef did not extend beyond 1 m. The measurable impacts of the LLR, on sedimentary oxygenation status, did not extend more than 1 m from the reef edge. At the reef edge, redox levels were highly variable with a mean expected reduction of 80 mV during the summer, at Group A. At other reef groups reef-proximity had less of an effect and there was a clear trend of decreasing change in mean redox from Group A to B to D and from summer to winter.