3.2. Local impacts and cyclonic versus non-cyclonic conditions
Water displacement, or velocity, plays an important role in reef habitats to deliver resources, remove waste, and disperse reproductive propagules (Denny and Shibata, 1989; Madin and Connolly, 2006; Monismith, 2007). In addition, Sebens et al. (1998) show that wave motion can lead to enhanced particle and zooplankton capture, such that periods of higher waves may benefit coral growth. Conversely, if wave-orbital velocity or wave forces exceed a certain value in any SLR scenario, coral may experience breakage, for example during cyclonic conditions. To investigate potential SLR impacts further, the change in wave-orbital velocity defined by the ratio Urms/Urms0 is adopted as an initial indicator of the impact of SLR on water displacements as a proxy for coral health. Here, Urms and Urms0 are the representative Urms velocities for the SLR condition and the baseline (SLR = 0) condition, respectively. Values of Urms/Urms0 greater or less than 1 indicate increases or decreases in wave-orbital velocity, respectively. Spatial variations in the impact of SLR in terms of this indicator were assessed for all bathymetries at different locations across the reef-lagoon transect; results presented here are for the fore-reef at a depth of 2 m below the elevation of the reef flat and at the centre of the reef flat. The ratios Urms/Urms0 on the fore-reef and reef flat for average wave conditions are plotted for varying reef flat depth ( Fig. 6) and as contours against reef width and reef depth ( Fig. 7).