Examining the influence of the newly delivered sediment and associated particulate nutrients in the inshore Great Barrier Reef

Stephen Lewis

This presentation addresses the question: What is the influence of the newly delivered sediment (i.e. from flood plumes) on turbidity regimes at coral reef and seagrass locations of the inshore GBR? Our logger data reveal a clear influence of the newly delivered sediment from flood plumes on both the initial suspended particulate matter (SPM) concentration and exposure (and the resultant light) during the plume event and, at some sites, in the resuspension events over the few months following the flood event. The particulate nutrients in association with the SPM also likely favour macroalgae growth at coral reef sites. The data also indicate that relatively small increases in SPM (~ 1 mg.L-1) can substantially reduce water clarity and light available to benthic autotrophs. Our new findings provide an enhanced process understanding for incorporation and validation to the eReefs model and help to better separate the influences of wave driven resuspension from dredging and newly delivered riverine sediment. The benefits of extensive end-user engagement and data sharing throughout the project life are also discussed.