Sediment grain size distributions differed between shelf locations within each season (Fig. 3a and b) with minimal variation within each shelf location. The mean grain size of trapped sediments differed significantly across inner-, mid-, and outer-shelf reef locations on the central GBR (Fig. 4 and Table 2), with trapped sediments being 1.7 and 8 times larger on outer-shelf reefs compared to mid- and inner-shelf reefs respectively. However, no seasonal differences were found in trapped sediment grain size (planned contrast analysis; mean grain size, F(1,72)=0.011, P=0.917), indicating suspended sediment stability and uniformity over time.