In ephemeral streams, floods can temporarily connect isolated pools and provide otherwise spatially restricted organisms with the option to stay in or leave a pool. A field survey of the middle-eastern fire salamander (Salamandra infraimmaculata) larvae demonstrated that 18% disappeared from pools during high-discharge events, and ∼2% were found subsequently in downstream pools.We conducted indoor experiments to test whether larvae alter drift rate in response to different velocities and perceived risk of predation. We manipulated flow velocities within the range of natural ephemeral streams during floods. Anesthetized larvae (passive drifters) drifted out of a central pool faster than conscious larvae at low velocities but not at high velocities, suggesting that conscious larvae actively resisted hydraulic pressures. Drift of small larvae out of a pool in the presence of a caged, larger cannibalistic conspecific was faster than in the absence of a predator, indicating that the larvae perceived and attempted to avoid the predator. Our findings confirm that larval drift that occurs from normally isolated temporary pools in ephemeral streams, is in part behaviorally controlled, and can be mediated by predation risk. We suggest that larval drift can serve as a dispersal pathway for amphibians and may be of particular importance at local spatial scales when the terrestrial habitat surrounding breeding sites is fragmented and movement of terrestrial stages is restricted.
- ephemeral streams
- temporary pools
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science