Upper Thermal Tolerance of the Endemic Freshwater StingrayPotamotrygon Magdalenaeand Inference on its Populations: An Endemic Potamotrygonid Resistant to High Temperatures Facing Thermal Changes

Abstract

ABSTRACTKnowledge 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 stingrayPotamotrygon magdalenaeacclimated 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 ofP. magdalenaepopulations. There were no significant differences between sexes in temperature tolerance or behavior. The Critical Thermal Maximum - CTMax (39ºC) was 5.9ºC above the maximum recorded temperature for the study area. AlthoughP. magdalenaewas 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 magdalenaeshows tolerance to high temperatures regardless of sex and size; however, can be threatened in the future if the temperature in its habitat continues rising.