Summer classification of Southern Hemisphere temperate lakes (Patagonia, Argentina)

Abstract

AbstractThe purpose of this paper was to synthesize observations of 21 cold temperate lakes from Patagonia, Argentina. To do this, objective limnological variables and the phytoplankton summer structure were analysed using multivariate statistical tools. The results suggest that the most important variables defined a trophic gradient based on nutrients, conductivity and phytoplanktonic attributes. Cluster analysis pointed to three groups of lakes. Steppe lakes (group III) were distinguished from mountain‐Andean lakes (groups I and II) through their higher conductivity and ammonia concentration values, higher net phytoplankton density and lower species diversity. The two groups of Andean lakes differed with regard to the biomass of Bacillariophyceae and Prymnesiophyceae, water temperature and dissolved inorganic nitrogen concentration. The influence of the biomass (as biovolume) of each taxonomic group in lakes of different trophic status was examined. Although all Andean lakes appear to be similar, as shown by their similar salt and nutrient concentration values, the phytoplankton biomass split into different taxa and clearly distinguished subgroups. The work presents original information about the phytoplanktonic community structure from all the lakes and the first limnological data on 10 of them, from a region that is poorly known.