KOPPRIO German Adolfo
congresos y reuniones científicas
Effects of climate change and eutrophication on the natural reserve Laguna Chasicó, a coastal brackish lake of Argentina.
KOPPRIO, G.; FREIJE, R. H.; HOFFMEYER, M. S.; POPOVICH, C. A.; STRUSSMANN, C. A.; LARA, R. J.
Bahia Blanca, Argentina
Conferencia; ECSA 44. Science and management of estuaries and coast: a tale of two hemisferes; 2008
ECSA, IADO, CONICET, UNS, ANPCyT
This lake was probably connected with the Bahía Blanca paleoestuary and is nowadays the lowest water body of South America (- 18m below m.s.l.). In this region there has been a rainfall increase over historic average since the 1970s, consequently this lake have experienced several dramatic floods. The inundation peak coincided with one of the strongest ENSO (El Niño-Southern Oscillation) events of the century. As consequence its salt content decreased from ~100 g l-1 to currently ~20 g l-1. This particular type of brackish ecosystem has favored the exceptional growth of Odontesthes bonariensis, a zooplanktivorous and commercially important fish. The main objective of this work is to understand the planktonic and pelagic community of this lake and its dependence on the hydrological regime in the current and under a climate change scenario. According to the high concentration of phosphates (5.37 μM) this lake is classified as hypereutrophic. The low N/P ratio (2.14) has favored cyanobacterial blooms. Toxic cyanophytes often responsible of fish mortalities such as Nodularia spp. and Oscillatoria sp. were detected. The biodiversity in the zooplankton is low: the copepod Boeckella poopoensis is the main species in abundance and biomass. Several models of global warming predict stronger ENSO events, with an increased inundation risk and further changes in the biota of the brackish lake. Two biological attributes of pejerrey, temperature-induced reproductive dysfunctions (e.g. thermolabile sex determination and heat-induced reduced fertility) and low adaptation to fresh water, make it particularly vulnerable to further increases in water temperature and rainfall, respectively.