PHYTOPLANKTON COMPOSITION AND DISTRIBUTION AS AN EXPRESSION OF PROPERTIES OF RESERVOIRS

Abstract

Some 335 sedimented samples of phytoplankton collected in 91 Spanish reservoirs (cold season of 1974–75) were counted. More than 250 species were recognized. A principal component analysis has been performed on the correlation matrix of the log-transformed densities of 41 species or groups of species, those preceded by a dash in Table 3 (Figure 1). The second component is related to mineralization (alkalinity, Figure 5), the third component to the fertility of water, and the fourth to the degree of stratification. The distribution on the plane defined by components III and IV segregates life-forms. The ordination of the reservoirs, according to their scores on the components II and III, is geographically coherent (Figures 3 and 4) and makes limnological sense (Table 3). These results can be compared with the ordination of the same reservoirs suggested before, and independently based on chemical data and on the composition of the phytoplankton collected with a net (1972–74). The agreement is satisfactory, ...