Sea turtle nesting threatened by beach lights

30/04/2009 12:13:02 Beach lights and rubbish hindering turtle conservation
April 2009. Sea turtles nest on beaches all over the world, but it is now understood that their nesting patterns can be severely disrupted by human disturbance, especially rubbish on beaches and beachside lights.

Florida turtles
Sea turtle nesting season has begun on Florida's beaches, which means beach residents and visitors must follow a few precautions to ensure a successful season.

Lights along the beach should be ‘managed' to prevent disorienting a female that comes ashore at night, according to biologists with the Florida Fish and Wildlife Conservation Commission (FWC). To do this, lights that are needed for human safety should be shielded so they are not visible from the beach or, preferably, turned off when not needed. The instincts of the ancient sea creature tell her to proceed toward the brighter horizon over the ocean. Bright lights on the landward side of the beach can confuse the nesting sea turtle and the hatchlings that emerge from the nest. Lights on the beach can lead them away from the ocean. 

Misplaced light can kill thousands of turtles
"Just one light can kill thousands of turtles over several years," said Dr. Robbin Trindell, a biologist with the FWC. "Many lights burn all night without contributing to human safety."

A leatherback sea turtle digs a nest on a Florida beach while a young boy practices responsible beach behavior by not disturbing the female's nesting patterns. The leatherback is the largest living turtle, reaching a weight of 1,500 pounds in some cases. Credit FWC

5 species of turtle nest on Florida's beaches
Five species of sea turtles nest on Florida beaches, with the loggerhead showing up in the largest numbers. Green and leatherback sea turtles also nest regularly, while two other species, Kemp's Ridley and hawksbill sea turtles, nest occasionally in Florida but inhabit Florida waters. The FWC lists the loggerhead as a threatened species; the other four are listed as endangered.

Loggerhead nesting
Nearly 90 percent of the loggerhead population that nests in the south-eastern United States does so on Florida's beaches. This population is one of only two large loggerhead nesting populations worldwide. Sea turtles are air-breathing reptiles well-suited for sea life with a hydrodynamic-shaped shell and large, powerful front flippers. These physical characteristics enable them to dive deep into the ocean and to swim long distances.

June-July is peak nesting in Florida
Female loggerhead turtles begin coming ashore in the spring, with peak months for laying eggs in June and July. The nesting female digs a hole with her hind flippers and then lays approximately 115 eggs. After covering the nest with sand, the massive creature, weighing from 150 to 300 pounds, makes her way back to the ocean. A female might come ashore two to five times during the nesting season. Amazingly, females come back to the same beach where they hatched decades earlier. The males, once they make the long crawl after hatching out of the egg, never return to land.

Loggerhead hatchlings can become disoriented by beach lighting as they try to head to the ocean. Credit FWC

Light pollution
Late in the summer, after an incubation of 55 to 70 days, the hatchlings begin breaking out of their shells. Up to 100 hatchlings wait below the sand surface until darkness, when they emerge together and crawl out of the nest. Instinct tells the 1- to 2-inch hatchling to head toward the brightest horizon and away from dark silhouettes. In days long gone in Florida, the brightest horizon shone over the ocean, and the hatchlings would move away from the shadows on the dunes and begin the crawl to the sea.

Rubbish danger
In modern-day Florida, hatchlings must crawl through a battlefield of debris left by humans. Furniture discarded by lazy beachgoers can obstruct a nesting female turtle or become a trap for the hatchlings. Avoiding firework leftovers strewn along the hatchling's path can cause exhaustion and delay in getting to the water. If a hatchling is stranded on the beach when the sun rises, its chance for survival diminishes, and dehydration and sun exposure become hazards.

"We can all help sea turtles survive," Trindell said. "If we just take personal responsibility, we can go a long way to ensure the sea turtle co-exists with us for many more years to come."
For wildlife-friendly lighting options, go to www.MyFWC.com/Conservation , and click on "Conservation & You."