Iglesias, Aimé LucilaFitoplancton, epipelon, materia orgánica y fósforo de una laguna arreica en relación con f

Abstract

The Alternative Stable States Hypothesis has been revised over the last years, owing to the differences found between shallow lakes from temperate zones and those from other latitudes and climates. Studies performed in shallow lakes of the Pam-pean region showed that the temporal and spatial changes and the interactions between algal communities are very complex. In these shallow lakes the epiphyton and epipelon may play significant roles that can be as or ever more important as the roles described for phytoplankton. In Lacombe Lake, three different phases of equilibrium were defined, one of them with intermediate characteristics between clear and turbid phases. The aim of this paper was to analyze the individual fit of some estimators of system dynamics of in-frequently used application in the equilibrium state definition to this conceptual scheme. The differences between phases were mainly identified in water variables, whereas sedi-ment variables did not show great variations although changes in system?s state were be-ing recorded. Chlorophyll a, phytoplankton density and water organic matter were the best indicators of the phases. With respect to sediment variables, the three phases were only differentiated on the basis of variations in the settled planktonic algae.