Upper thermal tolerance of the endemic freshwater stingray Potamotrygon magdalenae and inference on its populations

Abstract

Knowledge on thermal tolerance limits provide important clues to the capacity of a species to withstand acute thermal conditions. Climatic models predict the increase and intensification of events such as heat waves, therefore understanding the upper thermal limits that a species can tolerate, has become of utmost importance. We measure the upper thermal tolerance of the endemic freshwater stingray Potamotrygon magdalenae acclimated to experimental conditions, using the Critical Thermal Methodology (CTM). We also describe the behavior of individuals and infer the possible consequences of temperature increases in the habitats of P. magdalenae populations. There were no significant differences between sexes in temperature tolerance or behavior. The Critical Thermal Maximum - CTMax (39{o}C) was 5.9{o}C above the maximum recorded temperature for the study area. Although P. magdalenae was tolerant to high temperature and currently is not living at its upper thermal limit, its survival in Guarinocito Pond will be threatened if the increasing trend in temperature conditions keeps growing over time. SUMMARY STATEMENTPotamotrygon magdalenae shows tolerance to high temperatures regardless of sex and size; however, can be threatened in the future if the temperature in its habitat continues rising.