Efficiency of aquatic PIT‑tag telemetry, a powerful tool to improve monitoring and detection of marked individuals in pond environments

Identifying and tracking individuals across time are a prerequisite to uncover key traits of their ecology and behavior. However, obtaining fine-grain individual data at multiple locations, especially in aquatic environments, is challenging due to trade-offs between time constraints and detection probabilities. Aquatic telemetry of passive integrated transponder (PIT)-tagged organisms has been proposed to cope with detectability issues, but its efficiency
has not been tested in stagnant waters. This technology was evaluated in ponds by monitoring marsh frogs (Pelophylax ridibundus). Multivariate survival models were fitted to quantify the success of detection rates over detection times and across ponds characterized by different habitat features. An average detection rate of 81% was obtained in less than
18 min on average, whereas a maximum detection rate was achieved in almost a quarter of the surveys. The detection rates were lower in the deeper and larger ponds but increasing detection times improved detection probabilities. Altogether, these results show that PIT-tag telemetry is a powerful tool to survey aquatic organisms, such as pond-breeding amphibians. The generalization of the use of this monitoring technique in ponds can therefore encompass finegrain analyses over numerous sites and fill the gap between studies at local and landscape scales.