Influence of climate variations on ChascomA0s shallow lake thermal conditions and its consequences on the reproductive ecology of the Argentinian Silverside (Odontesthes bonariensis-Actinopterygii, Atherinopsidae)

It is well known that water temperature directly affects fish reproduction. The aim of this study was to develop a predictive model to determine water temperature conditions on a typical Pampas shallow lake (ChascomA(0)s, 35A degrees 36'S, 58A degrees 02'W) from local climate variables (specifically air temperature and rainfall). In addition, this model was used to assess the variability of local climate and water temperature conditions in this lake over the last 47 years, and predict possible effects on pejerrey reproductive phenology. The temperature model showed a good fit demonstrating a direct influence of the local climate into the lake water temperature. As consequence of a demonstrated warming in ChascomA(0)s City, an average increase of 1.4A degrees C was evident in ChascomA(0)s lake over the analyzed period, which was mainly due to a thermal increase during the warmer seasons (spring, summer, and autumn). This pattern of warming drove to a shortening in the pejerrey spawning season length, estimating a decrease of 19 days over the period of 47 years. Thus, this study showed that a tight association between the climate variability and the change in fish reproductive phenology can occur in species inhabiting shallow lakes.