Authors: Demare, Guillaume; Spieler, Marko;Grabow, Karsten;Rödel, Mark-Oliver;

Tropical savannas are globally extensive and ecologically invaluable ecosystems subject to serious anthropogenic stress. Defaunation, and especially the loss of large mammals, is pervasive in tropical savannas and known to trigger wide-ranging ecological effects, from vegetation changes to the loss of ecosystem function. However, virtually no research has investigated the effects of defaunation on small adjacent water bodies. This research gap persists because 1) tropical savannas have been historically neglected, 2) the ecological value of small water bodies is only recently being recognised, and 3) empirical baseline data is often lacking. In this study, we compared a rare pre-defaunation dataset with recently collected data on 213 freshwater assemblages, to investigate community structure and composition before and after a major defaunation event. Our research focused on a diverse species assemblage of amphibian larvae in temporary savanna ponds. Pond vegetation cover increased from 16.0% to 45.6% post-defaunation, i.e. a near three-fold increase. While some species have benefitted from such habitat changes, others have declined. These results shed new light on the potential role of large-bodied mammals in shaping adjacent ecosystems, and raise important questions concerning the functioning of temporary aquatic systems in the Anthropocene.