Características limnológicas y estructura de la ictiofauna de una laguna asociada al Río Quinto (Córdoba, Argentina)

Abstract

The Quinto river (Popopis) originates in San Luis province and connects by channels to numerous pampean shallow lakes. In the southern region of province of Córdoba, these wetlands provide different ecological services, many of which are linked to fish fauna. However there is little literature base in this regard. In march 2010, water quality and ichthyofauna structure of Onagoity shallow lake (34°46’25 “S, 63°38’37” W, 190 ha) were evaluated. The water was oligohaline (2.30 mg/L), very hard (314 ppm CaCO3) and sulfate-chloride-sodium type. The relationship Ca+Mg/Na+K was 0.23. The average values of pH, temperature, dissolved oxygen and transparency (Secchi disk) were 8.84, 23.5 ºC, 9.7 mg/L and 0.33 m respectively. In connection to the ichthyofauna, 13 species were captured belonging to 5 orders and 9 families: Odontesthes bonariensis, Cyprinus carpio, Jenynsia multidentata, Cyphocharax voga, Astyanax eigenmanniorum, Bryconamericus iheringii, Oligosarcus jenynsii, Cheirodon interruptus, Hoplias malabaricus, Corydoras paleatus, Loricariichthys anus, Pimelodus albicans y Rhamdia quelen. The diversity indexes of Simpson and Shannon-Wiener were 0.84 and 3.04 bits respectively and Pielou equity was 0.82. Considering all of the fishing gear used, silverside O. bonariensis was the most abundant species in number (31.0%), with a length-weight relationship: W = 0.578 E-06 * StL 3,149 (n = 92, R2 = 0.99, 95% CI of b = 3.11 to 3.18) and catch per unit effort (CPUE) of 26.1 kg/net/20 hours and 165 fish/net/20 hours.