Artificial light on water attracts turtle hatchlings during their near shore transit

We examined the effect of artificial light on the near shore trajectories of turtle hatchlings dispersing from natal beaches. Green turtle (Chelonia mydas) hatchlings were tagged with miniature acoustic transmitters and their movements tracked within an underwater array of 36 acoustic receivers placed in the near shore zone. A total of 40 hatchlings were tracked, 20 of which were subjected to artificial light during their transit of the array. At the same time, we measured current speed and direction, which were highly variable within and between experimental nights and treatments. Artificial lighting affected hatchling behaviour, with 88% of individual trajectories oriented towards the light and spending, on average, 23% more time in the 2.25 ha tracking array (19.5 ± 5 min) than under ambient light conditions (15.8 ± 5 min). Current speed had little to no effect on the bearing (angular direction) of the hatchling tracks when artificial light was present, but under ambient conditions it influenced the bearing of the tracks when current direction was offshore and above speeds of approximately 32.5 cm s−1. This is the first experimental evidence that wild turtle hatchlings are attracted to artificial light after entering the ocean, a behaviour that is likely to subject them to greater risk of predation. The experimental protocol described in this study can be used to assess the effect of anthropogenic (light pollution, noise, etc.) and natural (wave action, current, wind, moonlight) influences on the in-water movements of sea turtle hatchlings during the early phase of dispersal.

[1]  M. Hamann,et al.  Early swimming activity of hatchling flatback sea turtles Natator depressus: a test of the ‘predation risk’ hypothesis , 2009 .

[2]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[3]  M. Thums,et al.  Tracking sea turtle hatchlings — A pilot study using acoustic telemetry , 2013 .

[4]  Blair E. Witherington,et al.  Entendiendo, Evaluando y Solucionandolos Problemas de Contaminación de Luz en Playas de Anidamiento de Tortugas Marinas/Understanding, assessing, and resolving light- pollution problems on sea turtle nesting beaches , 2000 .

[5]  J. O’Hara.  Thermal Influences on the Swimming Speed of Loggerhead Turtle Hatchlings , 1980 .

[6]  K. Horch,et al.  Visual spectral sensitivity of hatchling loggerhead (Caretta caretta L.) and leatherback (Dermochelys coriacea L.) sea turtles, as determined by single-flash electroretinography , 2008 .

[7]  Christopher G. Lowe,et al.  Testing a new acoustic telemetry technique to quantify long-term, fine-scale movements of aquatic animals , 2011 .

[8]  M. Salmon,et al.  Orientation and swimming behavior of hatchling loggerhead turtles Caretta caretta L. during their offshore migration , 1987 .

[9]  C. Eizaguirre,et al.  Nano-tags for neonates and ocean-mediated swimming behaviours linked to rapid dispersal of hatchling sea turtles , 2014, Proceedings of the Royal Society B: Biological Sciences.

[10]  M. Salmon,et al.  Frenzy and Postfrenzy Swimming Activity in Loggerhead, Green, and Leatherback Hatchling Sea Turtles , 1992 .

[11]  K. Fritsches.  Australian Loggerhead sea turtle hatchlings do not avoid yellow , 2012 .

[12]  M. Salmon.  Artificial night lighting and sea turtles , 2003 .

[13]  M. Salmon,et al.  Effects of exposure to artificial lighting on orientation of hatchling sea turtles on the beach and in the ocean , 2007 .

[14]  S. Wood.  Fast stable restricted maximum likelihood and marginal likelihood estimation of semiparametric generalized linear models , 2011 .

[15]  Lohmann,et al.  Orientation and open-sea navigation in sea turtles , 1996, The Journal of experimental biology.

[16]  G. H. Jacobs,et al.  Photopic Spectral Sensitivity of Green and Loggerhead Sea Turtles , 2004, Copeia.

[17]  Dale M. Webber,et al.  Ultrasonic Telemetry, Tracking and Automated Monitoring Technology for Sharks , 2001, Environmental Biology of Fishes.

[18]  John P. Croxall,et al.  EFFECTS OF SATELLITE TRANSMITTERS ON ALBATROSSES AND PETRELS , 2003 .

[19]  E. Gyuris.  The rate of predation by fishes on hatchlings of the green turtle (Chelonia mydas) , 1994, Coral Reefs.

[20]  K. Pendoley.  Sea turtles and the environmental management of industrial activities in North West Western Australia , 2005 .

[21]  D. Booth.  Swimming for your life: locomotor effort and oxygen consumption during the green turtle (Chelonia mydas) hatchling frenzy , 2009, Journal of Experimental Biology.

[22]  Lohmann,et al.  Perception of ocean wave direction by sea turtles , 1995, The Journal of experimental biology.

[23]  Ruth M. Casper.  Guidelines for the instrumentation of wild birds and mammals , 2009, Animal Behaviour.

[24]  Peter M. Ostafichuk,et al.  Calculating the ecological impacts of animal‐borne instruments on aquatic organisms , 2013 .

[25]  Travis Longcore,et al.  Ecological consequences of artificial night lighting , 2006 .

[26]  David R. Anderson,et al.  Model selection and multimodel inference : a practical information-theoretic approach , 2003 .

[27]  Rory P. Wilson,et al.  When three per cent may not be three per cent; device-equipped seabirds experience variable flight constraints , 2012 .

[28]  N. Arai,et al.  Ontogeny of the dispersal migration of green turtle (Chelonia mydas) hatchlings , 2009 .

[29]  M. Salmon,et al.  Do swimming loggerhead sea turtles (Caretta caretta L.) use light cues for offshore orientation , 1990 .