Recent work also includes the development of a regional bio-optical algorithm for determining regional Secchi depth (ZSD) related to turbidity, clarity, and TSS in coastal waters in GBR waters over wet and dry seasons [59,61]. This algorithm has been used to calibrate MODIS time series of photic depth in GBR waters using inshore water quality collected through long-term monitoring programs [74,75]). The correlations between river loads of fine sediment (or proxies for these loads) and remote-sensed photic depth have been reported across the GBR [61]. For years of high river flow and large fine sediment loads, strong correlations are found across the entire GBR shelf. The correlations are strongest inshore in water depths of less than 20 metres and weaker correlations are observed further offshore. The effect of lower clarity in large river discharge years is driven by the river plume-delivered fine material, which contains large amounts of organic material in flocs [76] being resuspended in periods of strong winds and large tides (a characteristic in the central-southern GBR). This work is an integral part of recent work on modelling the influence of river flow and suspended sediments on the dry season turbidity of the GBR [59,61].