S2). Across years, mean photic depth was strongly related to Burdekin FG-4592 in vitro discharges (Fig. 5, R2 = 0.65). Burdekin discharges increased from low to higher values, with some periods of minor declines in between and a maximum in the year 2011. At the same time, there was a distinct gradual decline in mean photic depth (from

8.5 m to 6.5 m), with some periods of minor recovery in between, and a minimum in the year 2011. To determine how the suggested river influence extended across the shelf, the above analyses were repeated for the five cross-shelf transects separately (Fig. 6). The relationship of photic depth to Burdekin discharge values was strong for inshore, lagoon and midshelf bands (correlation coefficients: inshore: R2 = 0.61, lagoon: R2 = 0.64, midshelf: R2 = 0.56), weaker within the coastal strip that is chronically turbid (R2 = 0.45), and very weak for outer shelf waters (R2 = 0.24). The intra-annual Trametinib datasheet relationship between river discharge and the residuals of photic depth was also strong. Averaged across the ten years, the seasonal Burdekin River started discharging in January, peaked in March, declined

to low levels in April, and remained dry for the rest of the year (Electronic Supplement, Figs. S1 and S2). There were strong differences in the freshwater discharge volumes of the Burdekin River between water years, with four dry water years (2003–2006) being followed by six wet years with on

average 64.4% greater discharge volumes (2007–2012; Table 1). Data were therefore separated into the four dry and six wet water years. Averaged across the whole continental shelf, mean daily photic depth was 19.8% lower in the wet compared to the dry water years. The timing of the individual peaks and troughs, and the number of days of decline and recovery were relatively similar between these two sets of years, however the decline was more pronounced in the wet compared to the dry years (Fig. 7). In the wet years, regional mean photic G protein-coupled receptor kinase depth dropped below 10 m photic depth (a regional water quality guideline threshold; Great Barrier Reef Marine Park Authority, 2009) for 156 days, whereas in the dry years it was below 10 m for an average of 9 days per year. Standardized photic depth (i.e., the residuals from the GAMMs after removal of the environmental drivers) was highest in September to December, and steeply declined from December/January to April/May. From there on, photic depth started to increase again near-monotonously over a period of about four to five months, and returned to its maximum levels in the mid to late dry season (Table 2, Fig. 7). Regional daily mean photic depth was therefore reduced, from its dry season maximum, for about six to eight months after the Burdekin started flowing, included an approximately four months long period after the river discharges had subsided.