As temperatures drop on Long Island, sea turtle populations should too -- but when they don't, the turtles get sick, and marine experts are trying to raise awareness of those animals in need.

The Riverhead Foundation for Marine Research and Preservation will hold its 18th annual 5k Run for Ridley on Saturday as part of its Sea Turtle Awareness Month. The walk will wind through downtown Riverhead and include free water, snacks and juice, said foundation spokeswoman Rachel Bosworth.

The month itself also includes a lecture series with information on how to help during the cold season, she said. The goal is to draw attention to a condition called "cold-stunning" that affects sea turtles in the chilly northern waters between the end of October and January, she said.

"It's important for people to really start thinking about cold-stunning," Bosworth said. "Now this is the time of year when we do start to see a lot of sea turtles on the beach that are suffering from cold-stunning."

Most turtles begin to move south when the weather starts to get colder, but not all of them make it in time. Cold-stunning occurs when water temperatures drop below 50 degrees, said Robert DiGiovanni, the foundation's executive director and senior biologist.

The condition is similar to hypothermia and causes the animals to struggle to move and eat, he said. They may wash up on beaches, particularly on the North Fork, and appear dead, but many can be revived with attention from biologists.

Most sea turtles seen on Long Island, including the Kemp's Ridley turtle, are endangered, according to the state Department of Environmental Conservation.

"The critical thing is for the public to understand if they see a turtle on the beach and it's not moving, don't assume it's dead," DiGiovanni said.

Instead, the public should call the Riverhead Foundation's stranding hotline at 631-369-9829.

DiGiovanni added that they're asking the public to help comb the beaches to find stranded turtles, as the foundation has limited resources and receives most of the animals they treat after getting reports from the public.

advertisement | advertise on newsday

The cost to register for Saturday's event is $25. It costs $30 the day of the event. Check-in is from 8 a.m. to 9:30 a.m.

For more information about the run and lectures, visit riverheadfoundation.org.