Metabolism of a typical Pampean Shallow lake is governed by nutrients and seston

PADULLES LUZ; GIORGI ADONIS; ZUNINO EDUARDO; TORREMORELL ANA

Congreso; Congreso; Global Lake Ecological Observatory Network. All Hands' Meeting; 2022; 2022

GLEON

Shallow lakes in the Pampas region of Argentina are important for local economic activities and represent the typical “postcard picture” of the landscape. Pampas region is a very large grassland (1.2 x 106 km2) and has 10 500 shallow lakes ranging in size from 0.5 to 10 ha. We analyze metabolism, effects of nutrient dynamics and composition of picoplankton and phytoplankton in a typical Pampean shallow lake, Laguna de Lobos.Metabolic parameters: gross primary production (GPP), net ecosystem metabolism (NEM) and ecosystem respiration (R), show significant differences between autumn and summer. GPP there was positive correlation with soluble reactive phosphorus (SRP) and R there was negative correlation with pH. We performed a discriminant analysis with the variables that gave significant differences to properly classify the variables in the different seasons. The variables used were: hydrometric level, SRP and suspended particulate inorganic matter (SPIM) in the first function and total nitrogen (TN), R and suspended particulate organic matter (SPOM) in the second. The predominant algae were the filamentous cyanobacteria. Heterotrophic bacterial has a positive relationship with a TN and negative with secchi depht. The picocyanobacteria colonial form has a positive relationship with TP and negative with R and TN/PT.In this shallow lake, autotrophic metabolism predominance in spring and the heterotroph metabolism in the other seasons. In the annual cycle, predominance of heterotrophic metabolism. SRP and SPIN were explained variables of GPP seasonal variations and SPOM, chlorophyll and TN were explained variables of R seasonal variations.