Abstract
The Pampa Plain, in the central region of Argentina, is mostly drained by the Salado River. The fish fauna of this river is mostly known from field collections in lower reach lakes. Consequently, we aimed to explore the composition and structure of the fish assemblages in the upper Salado River lakes. Patterns in dominance and persistence of species and assemblage level attributes were correlated with environmental and human activity-derived (NO3:NH4) variables. Overall, 19,913 individuals of 17 species included in 5 orders and 11 families were collected. Several species are first records for the upper Salado River lakes. There was a marked proliferation of species in the family Characidae. Conversely, the remainder 10 families were only represented by one or two species. The species composition along the study lakes changed slightly but their relative contribution to the total fish collected (dominance) varied greatly. Rather few species were present in all collections suggesting an important interannual variability in assemblage stability. The gradient in water conductivity was an important factor for the persistence of particular species in the lakes. The gradients in water conductivity and NO3:NH4 ratio were associated with particular fish communities dominated by different groups of species. These results suggest that even when broad management and conservation strategies should encompass the system as a whole, lake-specific approaches must also be addressed. Overall, our results highlight that human impacts on surface waters may interact with environmental factors to influence the dynamics of fish species and the structure of their communities.
Highlights
The most recent biogeographical revision of Argentinean fishes (López et al, 2008) classifieds the fish fauna of the Salado River (Buenos Aires province) and its main tributary the Vallimanca stream into the Pampean province, sharing affinities with several drainages of central Argentina
Patterns in fish species composition and assemblage structure in Salado River lakes spite of that the southern boundary of the Brazilian subregion is located at the Negro River, in Argentina (Almirón et al, 1997) the Salado River basin already represents the southern range of many Neotropical species (Ringuelet, 1975; López et al, 2002)
In the upper Salado River lakes, species from Characiformes and Siluriformes orders made up more than 75% of the total fish fauna. This is a constant pattern of fish assemblage organization for most freshwater environments of South America (Lowe-McConnell, 1987; Rodríguez & Lewis, 1990; Pouilly et al, 1999)
Summary
The most recent biogeographical revision of Argentinean fishes (López et al, 2008) classifieds the fish fauna of the Salado River (Buenos Aires province) and its main tributary the Vallimanca stream into the Pampean province, sharing affinities with several drainages of central Argentina. This revision represents a major contribution to fulfil the “blank” in the scenario described in one of the latest synthesis of South America freshwater fish biodiversity (Junk, 2007). These lakes are highly fluctuating in salinity and water residence time (Quirós et al, 2002a) and had been largely modified by man and his use of land and water (Quirós et al, 2006)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
