The main supply of nitrogen to the Wadden Sea

The main supply of nitrogen (N) to the Wadden Sea is as nitrate (NO3) through the sluices in the Afsluitdijk, at Kornwerderzand and Den Oever. The ratio of N to P is higher than the Redfield ratio, implying that N is not limiting in spring. During summer and autumn the low discharge of dissolved N through the sluices, the removal of particulate N from the water column by intense grazing on phytoplankton by filter-feeders and the permanent removal through denitrification (Nitrate ? nitrogen-gas) drastically reduces the supply of N relative to P, making N the limiting nutrient.