Effects of Deforestation‐Induced Warming on the Thermal Tolerance of an African Clariid Catfish

Tropical countries, particularly in Africa, are experiencing more frequent deforestation events, often due to agricultural expansion. Deforestation can increase sunlight penetration in freshwater ecosystems, leading to increased average water temperatures and stronger diel temperature fluctuations.

To investigate the effects of deforestation‐induced warming and potential adaptive responses from fish, we compared the upper thermal tolerance limits of smooth‐head catfish (Clarias liocephalus) populations from deforested and forested sections of the Dura and Mpanga river systems in and around Kibale National Park, Uganda. We also incorporated a long‐term acclimation period in simulated forested/deforested water temperatures to test for differences in the thermal acclimation ability of two populations.

Populations from forested sites had lower CT_max values relative to populations sampled from deforested sections of the same drainage. However, long‐term acclimation in simulated deforested conditions increased their CT_max to values mirroring individuals from the deforested habitat. Individuals from a regenerating wetland (despite long‐term historical deforestation) exhibited CT_max values similar to populations from a forested site.

These results suggest that C. liocephalus may be able to thermally respond to deforestation‐induced warming under current global temperatures; however, results may have also revealed a potential thermal ceiling for the species.