Influence of climate variability on the composition of the fish community in the Middle Paraná River

ANA PIA RABUFFETTI

FABICIB

Universidad Nacional del Litora

Año: 2019 vol. 23

0329-5559

This thesis deals with the effects of climatic fluctuations occurred in La Plata basin during the last 100years on the fisheries of the Paraná River in its middle reach. The significance of hydroclimatic variablescompared with others accounting for anthropic impacts on the population changes of commercial species, was appraised. The results enabled to approach the probable influence on the ichthyofauna ofdistinct future climatic scenarios advanced for the basin. Data series covering more than 8 decades(1934-2016) of the most frequent and abundant commercial species inhabiting the main channel as wellas the nearby large floodplain of the Paraná River, were used. Fish attributes (biomass, size -Ls-, bodycondition factor) changed over time. Their long (short) term increments/reductions were closely relatedwith fluctuations of 18 hydroclimatic variables. Positive effects on the ichthyofauna were recorded during humid periods (1900-1940 and 1970-2000), when the frequency of large spring-summer floods increased (these floods had an average frequency of 4-6 years along the whole studied period). An increment of the anthropic incidence (accounted through 9 variables), was recorded during the last twodecades. Future hydroclimatic conditions as predicted by available models, would not be adequate forcommercial fisheries since a decrement of discharges and hydrological connectivity is expected and,thus, of the reproductive success and catches of the different species (particularly the large migrants).