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

Abstract

The 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.

Picoplankton abundance and cytometric group diversity along a trophic and latitudinal lake gradient

“…Lakes in Andean Patagonia were mainly formed by glacial and tectonic processes, which, together with hard rock composition and strong fluvial erosion, account for their typically very dilute waters; thus, these lakes are mostly ultraoligotrophic or oligotrophic. This region contains the largest and deepest glacial lakes in South America, situated in glacial valleys (Díaz et al 2000). The lakes on the Patagonian Plateau are generally shallower than the Andean lakes and range from mesotrophic to eutrophic (Quirós & Drago 1999), with higher total phosphorus and chl a values (Quirós & Cuch 1985).…”

Sporidiobolus longiusculus sp. nov. and Sporobolomyces patagonicus sp. nov., novel yeasts of the Sporidiobolales isolated from aquatic environments in Patagonia, Argentina

“…These aquatic environments are oligotrophic to ultra-oligotrophic temperate water bodies of glacial origin and have been classified as warm monomictic with a period of summer stratification (Díaz et al, 2000). Water samples were collected between December and January in 2001-2002 and in 2002-2003.…”

Populations of Odontesthes (Teleostei: Atheriniformes) in the Andean region of Southern South America: body shape and hybrid individuals

“…), conductivity (μS.cm -1 ), chlorophyll a (mg.m -3 ), Total Phosphorous (TP, mg.m -3 ), Total Nitrogen (TN, mg.m -3 ), and TN:TP ratio. Most of these data came from the ARLARE database (Quirós et al, 1988;Quirós, 1997) and other publications (IARH-INCYTH, 1995;Colautti et al, 1998;Díaz et al, 2000;Modenutti et al, 2000). Altitude, area, and perimeter were obtained from Google Earth (www.earth.google.com) and processed with Image Pro Plus 6.0 software.…”