Conceptual model showing how nitrogen (N) loading boosts algal and non-algal turbidity in shallow lakes. Firstly, N addition mitigates summer N deficiency, which increases algal biomass and subsequently causes higher P concentrations via feedback mechanisms between algal blooms and sediment P release. Secondly, N addition-triggered high algal biomass increases the abundance of deposit-feeding tubificid worms and therefore enhances non-algal turbidity via sediment resuspension.