The ability of an aquatic ecosystem to process impacts internally should also be assessed – dense Typha capensis reedbeds, for example, are often highly resilient in terms of their sensitivity to impacts like sediments, nutrient enrichment and other water quality impacts (Hall, 1990), while Ziegler et al. (2006) provide one example of research showing the efficacy of hardy Cyperaceae sedges (in this case Fimbristylis aphylla) in terms of sediment trapping and nutrient uptake.