Keep Lights Out for Loggerheads

By S.C. Dept. of Natural Resources

Published: October 7, 2009

The support of South Carolina coastal residents is needed more than ever before to raise awareness and educate our visitors to Keep Light’s Out for Loggerheads.  Loggerhead sea turtles nest on barrier islands in South Carolina from May through October. 
Currently in South Carolina, 21 disorientation events of loggerhead (Caretta caretta) hatchlings have been reported to the S.C. Department of Natural Resources (DNR) Marine Turtle Conservation program (http://www.dnr.sc.gov/seaturtle).  The number of disoriented nests per beach is:

* Hilton Head – 8
* Town of Edisto Beach – 4
* Isle of Palms – 4
* Cape Island – 3
* Sullivan’s Island – 1
* Hunting Island State Park - 1

These disorientation events may have affected as many as 2,520 hatchlings (the average number of eggs in a nest is 120).  The causes of these disorientations include streetlights, gas stations, exterior lights on commercial establishments, high density dwellings and beach front homes, including pool lights.  People on the beach at night carrying flashlights or lanterns, bonfires, and landscape lighting can also disorient loggerhead hatchlings.
When loggerhead hatchlings emerge from the shell they are attracted to blue and green wavelengths of light which are naturally reflected off the ocean through natural celestial light. They use this natural light to navigate from the nest towards the ocean.  This same mechanism is used by adult nesting females when nesting. If an artificial light source on the beach is brighter than the natural light, the hatchlings will head towards this artificial source.  These artificial lights can be a direct source such as a beach front home’s exterior flood light or a street light; the artificial light can also be indirect, scattered light that creates a sky glow effect.
When a hatchling sea turtle is attracted away from the ocean towards a direct or indirect source of light, biologists describe this as a disorientation event.  The hatchlings become disoriented and crawl away from the ocean towards the brightest light. During this disorientation event, hatchlings are more susceptible to nocturnal predators and desiccation.  While crawling the wrong way on the beach, hatchlings exhaust valuable, limited energy stores needed to swim offshore.  Hatchlings need energy once in the ocean to swim towards floating Sargassum seaweed found 10 – 15 miles offshore. They use the seaweed as camouflage to protect them from predators.  The seaweed is also home to small crustaceans that loggerhead hatchlings eat to replenish their energy.
From May to mid-August, loggerheads come ashore to deposit approximately 120 eggs in a nest cavity in the dry sand dune system.  Sixty days later, loggerhead hatchlings emerge out of the nest at night and head to the ocean.  Nests hatch from July through the end of October.  Loggerheads are listed as threatened under the Endangered Species Act and are protected by federal and state laws.
County and local lighting ordinances exist to protect sea turtles.  To see a list of lighting ordinances in South Carolina, please visit (PDF file): http://www.dnr.sc.gov/seaturtle/volres/ordinances.pdf.  Violating local or county lighting ordinances carry fines up to $500.  If a sea turtle hatchling is disoriented by artificial light, the maximum federal fine for harming a threatened species is $25,000. As coastal development continues to increase, the number of disorientation events will also rise.  The loggerhead nesting population in the southeastern United States is continuing to decline and it has been recommended that this species be reclassified from threatened to endangered.
Follow sea turtle nesting and stranding in South Carolina in real time. Visit our sea turtle nest monitoring page (http://www.seaturtle.org/nestdb/index.shtml?view=2) and our sea turtle stranding page (http://www.seaturtle.org/strand).
South Carolina’s natural resources are essential for economic development and contribute nearly $30 billion and 230,000 jobs to the state’s economy overall. Find out why “Life’s Better Outdoors” at: http://www.dnr.sc.gov/green/index.html.