1 3 Oecologia (2017) 184:151–160 DOI 10.1007/s00442-017-3862-z BEHAVIORAL ECOLOGY –ORIGINAL RESEARCH Tuned in: plant roots use sound to locate water Monica Gagliano 1 · Mavra Grimonprez 1 · Martial Depczynski 2,3 · Michael Renton 4 Received: 31 October 2016 / Accepted: 31 March 2017 / Published online: 5 April 2017 © Springer-Verlag Berlin Heidelberg 2017 the abilities of roots to perceive and respond correctly to the surrounding soundscape. These findings highlight the urgent need to better understand the ecological role of sound and the consequences of acoustic pollution for plant as well as animal populations. Keywords Foraging behavior · Hydrotropism · Moisture sensing · Bioacoustics · Directional root growth Introduction All living organisms have basic needs and can only sur- vive in environments where vital resources are available for those needs to be met. Water is one of those essential resources and its availability plays a critical role in terres- trial ecosystems where it strongly influences abundance, spatial distribution and species interactions of a wide range of plant and animal groups (Hawkins et al. 2003; McCluney and Sabo 2009; McCluney et al. 2012; Ledger et al. 2013). Because water is often limited and can be unevenly distrib- uted across time and space, both animals and plants have evolved a number of morphological and physiological traits as well as behavioral strategies to cope with water scarcity and avoid dehydration. Ultimately when faced with water scarcity, both animals and plants have two main options: water-saving or water-seeking. Several animals and plants have evolved to cope with water scarcity through their impressive physiological capacity to save previously acquired water (e.g., cam- els, Bekele et al. 2013; cacti, Niklas 1997). Taken to an extreme, bryophytes like the so-called ‘resurrection plants’ can remain in a dried state for years and then, rehydrate and return to a fully functional state within 48 h of rain (Scott 2000). These and many other morphological and Abstract Because water is essential to life, organisms have evolved a wide range of strategies to cope with water limitations, including actively searching for their preferred moisture levels to avoid dehydration. Plants use moisture gradients to direct their roots through the soil once a water source is detected, but how they first detect the source is unknown. We used the model plant Pisum sativum to inves- tigate the mechanism by which roots sense and locate water. We found that roots were able to locate a water source by sensing the vibrations generated by water mov- ing inside pipes, even in the absence of substrate moisture. When both moisture and acoustic cues were available, roots preferentially used moisture in the soil over acoustic vibra- tions, suggesting that acoustic gradients enable roots to broadly detect a water source at a distance, while moisture gradients help them to reach their target more accurately. Our results also showed that the presence of noise affected Communicated by Hermann Heilmeier. Electronic supplementary material The online version of this article (doi:10.1007/s00442-017-3862-z) contains supplementary material, which is available to authorized users. * Monica Gagliano monica.gagliano@uwa.edu.au 1 Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, WA 6009, Australia 2 Australian Institute of Marine Science, Crawley, WA 6009, Australia 3 Oceans Institute, University of Western Australia, Crawley, WA, Australia 4 School of Plant Biology, University of Western Australia, Crawley, WA 6009, Australia