|Eutrophication of the western Dutch Wadden Sea, a short review|
Van Raaphorst, W.; Mom, B. (1995). Eutrophication of the western Dutch Wadden Sea, a short review, in: Morán, X.A.G. et al. (Ed.) (2006). Oceanography of the Bay of Biscay. Scientia Marina (Barcelona), 70(Suppl. 1): pp. 5-16
In: Morán, X.A.G.; Rodríguez, J.M.; Petitgas, P. (Ed.) (2006). Oceanography of the Bay of Biscay. Scientia Marina (Barcelona), 70(Suppl. 1). Institut de Ciències del Mar: Barcelona. 208 pp., more
In: Scientia Marina (Barcelona). Consejo Superior de Investigaciones Científicas. Institut de Ciènces del Mar: Barcelona. ISSN 0214-8358, more
|Authors|| || Top |
- Van Raaphorst, W.
- Mom, B.
A short review is given on existing literature and data on the eutrophication of the western Dutch Wadden Sea. An extension is made of the previously published trends to the early nineties. Eutrophication is defined here as any increase in the rate of supply of nutrients or organic matter to an ecosystem. Effects of increased nutrient loads e.g. increased algal blooms are not included in this review. Annual loads of total P and total N in the river Rhine at Spijk/Lobith have decreased since 1982-1987 to values comparable to those in the sixties and early seventies. Due to inputs in the Dutch part of the drainage basin of the Rhine, total nutrients loads from the Rhine to the North Sea have decreased substantially less during the last decade. The recent decrease in the nutrient loads from the Rhine is not reflected in the N and P concentrations in Dutch coastal waters close to the Wadden Sea. The total P and total N concentrations in the northern part of Lake Ijssel as well as the discharges from the lake into the Wadden Sea follow a similar decrease as the loads of the Rhine since the mid-eighties, however with a time lag of a few years. At present, discharges into the Wadden Sea are as low as before the seventies. Concentrations of total P and N in the western Wadden Sea followed the steep increase in the loads from Lake Ijssel in the early seventies, but showed different trends hereafter. In contrast to Lake Ijssel and the adjacent North Sea both N and P dropped since 1978-1983, i.e. some years before the onset of the decrease in the main nutrient sources, and stabilized at relatively low levels since then. This suggest a major role of internal processes in controlling nutrient levels in the Wadden Sea. At present the concentrations are comparable to those in the sixties and early seventies.