ALBERT

Description: Estimates of significant wave height and period, together with tidal current speed over a semi-lunar cycle, were used to predict the area on the Australian continental shelf over which unconsolidated sediment was mobilised (threshold exceedance). These sediment-entraining processes were examined independently to quantify their relative importance on the continental shelf. Using observed grain size data, mobilisation from swell waves occurred on ∼31% and tidal currents on ∼41% of the continental shelf. Swell wave energy is sufficient to mobilise fine sand (0.1 mm diameter) to a water depth of 142 m on the Otway Shelf near the western entrance to Bass Strait. Tidal currents in King Sound (northwest shelf) are capable of mobilising large areas of medium sand (0.35 mm diameter) 100% of the time. Superimposing the distribution of threshold exceedance by wave and tidal currents indicates that there are areas on the shelf where either wave-induced or tidal currents dominate, some areas where waves and tides are of relatively equal importance and still other areas where neither is significant. We define six shelf regions of relative wave and tidal energy: zero (no-mobility); waves-only, wave-dominated, mixed, tide-dominated and tides-only. Our results provide a predictive, process-based understanding of the shelf sedimentary system that has applications to marine engineering projects and to regional studies of pollution dispersal and accumulation where significant shelf sediment mobilisation is a factor.

Description: Recently, researchers have begun to identify the prevalence of trait simplification, loss and reversal across all levels of biological organization. These studies have taken increasingly integrated approaches, incorporating phylogenetic, developmental and molecular methods, in the quest towards understanding the patterns and processes behind evolution in reverse. Here, we highlight the emerging interest in the reversibility of evolution by discussing a spectrum of studies examining both the genotypes and phenotypes of evolution in reverse. These integrative approaches have greatly increased our knowledge of the biological interactions that produce patterns of evolution in reverse and have led to promising new areas of research.