Ecological characterization of the assemblages of potentially toxic bloom-forming Cyanobacteria in Pampean shallow lakes (Argentina)

INÉS O'FARRELL; MARÍA PAULA HUBER; MIGUEL MANCINI; IRINA IZAGUIRRE; ROMINA SCHIAFFINO; CAROLINA GONZÁLEZ; LILEN YEMA; MARÍA LAURA SÁNCHEZ; LEONARDO LAGOMARSINO; FIORELLA COCCIOLO

Cracovia

Conferencia; 11th International Conference of Toxic Cyanobacteria; 2019

Pampean shallow lakes (Argentina) are affected by blooms of toxic cyanobacteria (CyanoHABs) since the middle of the last century. Although these shallow and typically eutrophic systems are habitats that favor CyanoHABs development, the recent and strong increase in nutrient concentration and the high frequency of extreme drought events (associated with the intensification of agriculture and climate change respectively), have accelerated this problem. The environmental determinants that affect the success of the different species differ according to the morpho-functional features conferring fitness for the acquisition of nutrients and light, among other factors. The objective of this work is to temporarily characterize CyanoHABs in shallow lakes with different limnological characteristics.In the framework of the PAMPA2 network project (CONICET), monthly monitoring of nine lakes located along a humidity gradient in the Pampa Region was performed between October 2012 and December 2015. The structure of the assemblages of bloom forming planktonic cyanobacteria was analyzed considering both species and eco-strategies abundance and biovolume. Our results indicate that the composition and intensity of the blooms are more likely to be affected by the conditions of nutrients, light and macrophyte development than by the location of the lake in the geographical gradient. The composition and abundance varied annually in close relationship with the water regime.In addition, total microcystin concentration was analyzed in warm periods for six lakes; the toxin was found in all systems, generally at levels below 1 μg / L (WHO guide level); inter-annual differences were found.Individual (colonies and filaments) morphological variations were analyzed in one lake (Salada de Monasterio), observing relationships between filament length and turbidity, which affect the biomass.