title: Earth-strength magnetic field affects the rheotactic threshold of zebrafish swimming in shoals.
abstract: Rheotaxis, the unconditioned orienting response to water currents, is a main component of fish behavior. Rheotaxis is achieved using multiple sensory systems, including visual and tactile cues. Rheotactic orientation in open or low-visibility waters might also benefit from the stable frame of reference provided by the geomagnetic field, but this possibility has not been explored before. Zebrafish (Danio rerio) form shoals living in freshwater systems with low visibility, show a robust positive rheotaxis, and respond to geomagnetic fields. Here, we investigated whether a static magnetic field in the Earth-strength range influenced the rheotactic threshold of zebrafish in a swimming tunnel. The direction of the horizontal component of the magnetic field relative to water flow influenced the rheotactic threshold of fish as part of a shoal, but not of fish tested alone. Results obtained after disabling the lateral line of shoaling individuals with Co2+suggest that this organ system is involved in the observed magneto-rheotactic response. These findings constitute preliminary evidence that magnetic fields influence rheotaxis and suggest new avenues for further research.
authors.affiliation: Rosenstiel School of Marine & Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, USA.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cresci
authors.affiliation: Department of Physics, University of Naples Federico II, MSA Campus, Via Cinthia 21, 80126 Napoli, Italy; INFN, Section of Naples, MSA Campus, Via Cinthia 21, 80126 Napoli, Italy.
authors.forename: Rosario
authors.initials: R
authors.lastname: De Rosa
authors.affiliation: Cooperative Institute for Marine & Atmospheric Studies, Rosenstiel School of Marine & Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, USA; Atlantic Oceanographic and Meteorological Laboratory, National Oceanic and Atmospheric Administration, Miami, FL 33149, USA.
authors.forename: Nathan F
authors.initials: NF
authors.lastname: Putman
authors.affiliation: Department of Biology, University of Naples Federico II, MSA Campus, Via Cinthia 21, 80126 Napoli, Italy. Electronic address: agnisola@unina.it.
authors.forename: Claudio
authors.initials: C
authors.lastname: Agnisola
mesh_terms: D000818:Animals; D005618:Fresh Water; D060526:Magnetic Fields; D013550:Swimming; D015027:Zebrafish / Q000502:physiology*
keywords: Magnetic field; Orientation; Rheotaxis; Shoal; Zebrafish