1.?Introduction . Human activities have dramatically altered global nutrient cycles, resulting in a remarkable rise of global nitrogen emissions since the 1950s (Steffen et al 2015 ), mainly stemming from fertilizers, wastewater, and atmospheric deposition (Caraco and Cole 1999 , Fowler et al 2013 ). However, the effects of changes to the nitrogen cycle on aquatic ecosystem integrity are modulated not just by the amount but also by the timing (i.e. seasonality) of the nutrient av...