PRODUCTIVIDAD, ESTADO TRÓFICO Y DINÁMICA FITOPLANCTÓNICA EN LA LAGUNA SAUCE GRANDE Y SU AFLUENTE HOMÓNIMO (PCIA. DE BUENOS AIRES, ARGENTINA)

MARTÍNEZ A. M.; CONY N.; CACERES E.; FERRER N.

Biologia Acuatica

Instituto de Limnologia

Año: 2016 vol. 31 p. 50 - 62

1668-4869

The shallow lake Sauce Grande is located in the southwest of Buenos Aires province.It is a widening of the Sauce Grande River that flows in and out of the lake. The aim of this studyis to estimate for the first time the primary productivity (PP) of this lake and to contrast thephysiochemical variables, phytoplankton structure and trophic status with those of its maintributary. Monthly samplings (April-September 2014) were performed in the middle basin of theriver and on the coast of the lake. We recorded in situ physical and chemical parameters with amultisensor Horiba U-10. Phytoplankton samples were collected with a plankton net for thequalitative study and with plastic bottles for quantitative analysis.The greatest physicochemicaldifferences corresponded to turbidity and conductivity with values of 581.3 NTU and 9 mS/cm forthe lake and 17.7 and 1.7, for the river. The average PP in the lake was 252.1 mg C/m3.h.Cyanobacteria were the most abundant taxonomic group in both systems, although itsabundance was greater in the shallow lake. The Carlson index, based on the concentration ofchlorophyll a and total phosphorus, identifies the lake as eutrophic, while the river was classifiedas oligo-mesotrophic according to the same variables. Our results suggest that the SauceGrande Lake is an autotrophic system with a highly productive metabolism. The remainingproduction becomes biomass and accumulates within the system, in the form of high levels ofphytoplankton abundance, in particular a massive proliferation of Cyanobacteria.