Exploring relationships among hydrology, human disturbance and fish abundance in a series of very shallow lowland river lakes

ROSSO, JUAN JOSE; QUIRÓS, ROLANDO

Cochabamba, Bolivia

Congreso; International Congress on Development, Environment and Natural Resources: Multi-level and Multi-scale Sustainability; 2007

The study lakes are very shallow hypertrophic environments located at the populated headwaters of Salado River, in the Pampa plain, Argentina. The highly fluctuating flow regime and the anthropogenic impacts probably impose stressful and variable conditions on fish. Our objective is to explore how abundance of the 5 major fish species of these lakes is related with several environmental and human factors. Variation in fish abundances was significantly related with anthropogenic or environmental variables in 4 species. Fish abundance of bottom-dwelling species were positively related with anthropogenic variables and showed inverse relationships with water residence time (Tw). Conversely, a planktivorous fish was positively correlated with water conductivity and Tw and would be negatively affected by human disturbance. Small carnivorous showed no significant correlations with any variable. Our findings suggest that hydrological stress might exert abiotic control on fish assemblages in shallow lowland river lakes, whereas anthropogenic impacts should also be considered important.