LAUSR

Many riverine systems experience periodic flooding events as part of their natural flow regimes. These events can provide nutrients, create access to seasonal environments, and refill associated wetlands (Junk et al., 1989; Pringle, 2001). Understanding the effects of flooding events is particularly important because of the widespread alteration of flow regimes by humans, both deliberately (e.g., electricity generation and regulation for agriculture) and inadvertently (e.g., climate change; Nilsson et al., 2005). Nevertheless, there are still many knowledge gaps regarding the effects of floods on aquatic organisms. Aquatic turtles are one of the key groups for which the effects of flooding are still understudied. Turtles are important members of aquatic ecosystems that serve numerous ecological roles and often comprise a large portion of the vertebrate biomass (Lovich et al., 2018; Santori et al., 2020). They are also among the most critically endangered vertebrates (Stanford et al., 2020), and changes in flood regimes could depress their populations. Some turtle species have life histories that are closely linked to flow regimes, with floods either providing resources (Georges & Guarino, 2017) and access to new habitats (Bodie & Semlitsch, 2000; Doody et al., 2002) or triggering hatching and nest emergence (Doody et al., 2001). For most species, however, their associations with floods are poorly understood, and this knowledge gap could hamper conservation efforts. Here we report a large and rapid increase in the surface activity of the Mexican giant musk turtle (Staurotypus triporcatus; a near-threatened species of bottom-dwelling turtle) following a flooding event. We discuss hypotheses regarding Received: 1 April 2022 Revised: 27 July 2022 Accepted: 3 August 2022