CINDY ELLEN RUSSELL / CRUSSELL@STARBULLETIN.COM
Studies at Sea Life Park are under way to narrow down the temperature range that determines the gender of sea turtles.
Researchers try to determine whether nest temperatures influence the gender of unborn Hawaiian green sea turtles
Whether it's a boy or a girl might have something to do with "nest temperatures."
And when it comes to Hawaiian green sea turtles, nest temperatures could be an important factor in keeping the ratio of females and males about the same, some scientists believe.
"It's one of the last great mysteries left for Hawaiian sea turtles," said biologist George Balazs, head of the Marine Turtle Research Team of the National Marine Fisheries Service. This is the first time this type of research is being done in Hawaii on the endemic, threatened species.
Sea Life Park, the Marine Turtle Research Team of the National Marine Fisheries Service and the University of Alabama at Birmingham are working together to determine whether pivotal temperatures are the reason for gender determination for Hawaiian green sea turtles. Experts believe warmer temperatures produce females while cooler temperatures produce males.
Data is expected to be available in four months, with researchers continuing their work through 2007.
"(Hawaii) has relatively cool nesting beaches compared to other beaches in the world where sea turtles nest," said Thane Wibbels, associate biology professor of the University of Alabama and principal scientist on the study.
Researchers believe Hawaii's turtles have adapted to those cooler temperatures, producing an equal ratio of males and females.
Balazs has operated a stranded and salvage team for sea turtles in isle waters for 22 years. Through his research, autopsies performed on dead turtles showed an equal ratio of males and females. When they are too small, their gender cannot be determined based on their appearance, he said.
"The study will help reaffirm that our field studies are indeed correct, that we have a 1-to-1 sex ratio or thereabouts, meaning it's a healthy, balanced male-to-female sex ratio," Balazs said.
Balazs has been studying green sea turtles for 37 years and said Hawaii's nesting temperatures are quite low compared with other nesting beaches in the world.
"There should be a larger number of males," he said. Experts believe that the Hawaiian green sea turtle population has adapted to "significantly lower pivotal temperatures. The temperature seems to have shifted in the Hawaiian green sea turtles. At least, that's what we're investigating," Wibbels said.
The study is significant for conservation and preservation reasons as well as to determine how the turtles adapt to climate changes. "They demonstrated to be very adaptable," said Dr. Renato Lenzi, general manager of Sea Life Park. "The more we can find out about them now, the more we'll be able to predict down the road."
About 130 to 140 eggs are being used in the study. About 200 turtles will be used for the study before they are released into the ocean. Eggs are hatched in the sand by female Hawaiian green sea turtles in the conservation colony of Sea Life Park. Since 1976 about 400 to 1,000 hatchlings have been produced at the park annually.
Each egg is marked and incubated for about 60 days. When the turtles hatch, each is tagged on its flippers to determine the incubator in which it is placed. When the turtle is big enough, about 8 inches in diameter, experts conduct a laparoscopic procedure to determine whether the turtle is male or female.
A majority of the Hawaiian green sea turtles nest at the French Frigate Shoals about 400 miles off Kauai. It takes about 20 to 35 years for the turtles to reach maturity, Balazs said.