The Effects of Artificial Light Intensity on Sea Turtle Nesting Behavior at Playa Cabuyal, Guanacaste, Costa Rica

Alexander Silowsky, Purdue University


Fine-scale light intensity sampling was conducted at Playa Cabuyal, a remote, unprotected beach in the Guanacaste province of Costa Rica. These data were then interpolated and used to determine the relationship between light intensity and sea turtle nesting locations of three species as well as the prevalence of false crawls by these nesting turtles. Mean light intensity during nighttime surveying sessions during the wet season on 20-24 November ranged from 0.51 ± 0.01 lux to 0.53 ± <0.01 lux, with occasional spikes in light intensity as high as 0.56 lux obtained near the only private residence on the beach. Sea turtle nesting data collected over six nesting seasons revealed that nesting success (“nesting success” here defined by oviposition) within the segment of beach illuminated by the private residence was not significantly altered by increased light intensity for black (p = 0.676), leatherback (p = 0.875), or olive ridley sea turtles (p = 0.963). The illuminated sectors were not found to have any impact on sea turtle nesting success for any of these tested species. The presence of light at the private residence was found to have a beach-wide impact on the nesting success rate of black sea turtles (p = 0.013) irrespective of proximity to the sectors in which increased light intensity was detected, suggesting that visibility of the light fixture itself has a greater impact on sea turtle nesting success than light intensity at the site of the nest.




Paladino, Purdue University.

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