The efficiency of seven diversity and one similarity indices based on phytoplankton data for assessing the level of eutrophication in lakes in central Sweden

Seven diversity and one similarity indices calculated on the basis of phytoplankton data were studied for their usefulness for eutrophication studies in lakes in central Sweden. The lakes of different eutrophication levels (eutrophic, mesotrophic and eutrophic) were investigated monthly during autumn 1998. All of the diversity indices calculated (Hurlbert's, Margalefs, Menhinick's, Shannon's, Simpson's, McNaughton's and Species Number) failed to distinguish between different levels of eutrophication. However, the use of similarity index based on presence-ab sence matrices of phytoplankton species proved its high efficiency for eutrophication studies in the lakes in central Sweden. The consideration of abundance, additionally to presence-absence data, was concluded not to be as efficient as only presence-absence matrices. We recommend the use of similarity index based on presence-absence matrices of phytoplankton species as a good tool for the assessment of the level of eutrophication in the lakes studied. (C) 1999 Elsevier Science B.V. All rights reserved.