Graphs of periphyton (as mean chlorophyll a) versus mean soluble reactive phosphorus - SRP (top), mean soluble inorganic nitrogen - SIN (middle) and mean water temperature (bottom), with sites coded by frequency of mobility (symbol shape) and degree of shade (symbol shade). Low mobility sites have sand mobile <10% of days. High mobility sites have sand mobile >10% of days. [after Hoyle et al. 2016]