Temperature and massive fish deaths in southern South America

Abstract

Based on a compilation of data on massive fish deaths occurred in southern South America during the
Twentieth Century, we assessed the importance of climatic variables on these phenomena. We found a strong relationship
(R2 =0.68) between these massive fish deaths and the mean monthly air temperature. Along the annual
temperature range there is a central range (14.6° C to 20.0° C), where the probabilities that a fish community
suffers massive deaths is very low. Its central point (17.3° C) is very close to the mean annual value (17.2° C) of
air temperature variation. We considered this agreement as corroboration at community level of Pianka’s theory
on physiological optima. This relationship allows to monitoring the influence of climate changes, because the
environmental variation and the zones of mortality and no mortality will change with predicted changes of the
mean monthly values of air temperature.