The trophic state of shallow lakes in The Netherlands

Abstract

A study has been carried out on the development of an ecological assessment method for shallow lakes in The Netherlands. Analyses of eutrophication characteristics of 93 lakes with, in total, 127 sampling localities gave insight into some of the steering variables, such as total-P, total-N, chlorophyll-a and transparency. On the basis of phytoplankton species composition, three main groups of lakes could be distinguished. The first group, characterized by persistent filamentous Cyanobacteria, had the highest summer means of chlorophyll-a and totaI-P. The second group was characterized by non-persistent filamentous Cyanobacteria, occurring in low abundancies, and at lower chlorophyll-a and totaI-P concentrations. The third group of lakes was characterized by the absence or very low abundance of the filamentous Cyanobacteria. As a result of these analyses, criteria for the abatement of eutrophication in shallow lakes could be refined.

Comparison of the light‐limited growth of the nitrogen‐fixing cyanobacteria Anabaena and Aphanizomenon

“…present in eutrophic shallow freshwater lakes (Mur & Schreurs, 1995 ;Roijackers & Joosten, 1996). In general, cyanobacterial species capable of N # fixation will have a competitive advantage over non-diazotrophs if N # is the only N source available for growth.…”

Competition for phosphorus between the nitrogen-fixing cyanobacteria Anabaena and Aphanizomenon

“…and Aphanizomenon spp. occur regularly [2, 3], but it is not yet clear what leads to the dominance of either species. Although cyanobacterial N 2 fixation activity is primarily stimulated by low levels of combined inorganic nitrogen, it is also dependent on the availability of e.g.…”