Mamma turtle is a Loggerhead with this unusual track due to an injury to her right hind flipper. Jump to. Sections of this page. Accessibility Help. Email or Phone Password Forgot account? Sign Up. See more of Sunshine Coast Council on Facebook.
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Related Pages. Sunshine Coast Daily. Sunshine Coast Libraries Government Organization. Whats On? Sunshine Coast Community Organization. ABC Sunshine Coast. But that's invasive, and not so practical if you're hoping to examine hundreds of creatures. Jensen was stumped. At a turtle conference in Mexico, he bumped into Allen, a former koala researcher. Allen had used testosterone levels to track pregnancies in the tree-loving marsupials.
She went on to perfect ways of deciphering the sex of marine species based on hormone levels. All she needed was a little blood. The pair teamed up with others, including Australian turtle expert Ian Bell, and drew blood from Great Barrier Reef turtles. They performed a few laparoscopy exams to confirm the accuracy of Allen's methods. They compared their results with temperature data for nesting beaches. And they examined turtles of varying age.
The results caught them by surprise.
FLORIDA SEA TURTLE NESTING SEASON IS HERE
It appears that Raine Island has been producing almost exclusively female turtles for at least 20 years. This is no small thing. Eighty-acre Raine and its associated coral cays host one of the largest green sea turtle rookeries on Earth, where more than , turtles come to nest. During high season, 18, turtles may settle in at once. And those are just the females. Since scientists also were able to determine rough ages for the turtles they sampled, they also made another discovery.
Along that stretch of the northern Great Barrier Reef, where increasing heat had led to significant coral bleaching in recent years, the ratio of females to males had grown more severe with time. Turtles that hatched there around the s and s were also mostly female, but only by a ratio of 6 to 1. He was not affiliated with the study. The scope—encompassing the length of the Great Barrier Reef—and the multidisciplinary approach make the research highly valuable, he says.
Equally important is what Jensen and Allen found down south. There, turtles hatching from the southern reef near Brisbane—where temperatures have not increased as significantly, and where corals remain quite healthy—fare far better. There, female turtles today outnumber males by only 2 to 1. More work needs to be done to assess the changing sex ratios of green sea turtles in other parts of the world, such as this animal in the Galapagos Islands.
Since male sea turtles often mate with more than one female, and males typically mate more frequently, a slight female bias may be beneficial. A recent look at 75 sea turtle rookeries around the world showed the ratio of females to males was roughly 3 to 1. In fact, some turtle populations produced fewer males than females even a century ago. The question, though, is: how much has it changed, and how much is too much?
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Marine turtles have been around for million years and temperatures have risen and fallen during that time. Plus, after decades of decline from hunting, poaching, pollution, disease, development, habitat loss, and bycatch in commercial fishing, many populations around the world recently have shown signs of improvement.
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But these are animals that live for 50 years or more, and things are changing dramatically just in their lifetimes. Just on Raine Island alone, for example, rising seas have inundated nest sites, drowning eggs. Beach erosion is creating mini-cliffs, causing adult greens to fall onto their backs and die, unable to right themselves.
Australian authorities are spending millions of dollars restoring the island to improve life for turtles. Even so, scientists have been predicting for at least 35 years that the male-female balance of all seven sea turtle species—greens, loggerheads, leatherbacks, hawksbills, flatbacks, olive, and Kemp's ridleys—would be exceedingly vulnerable to climate change.
The reptiles are so temperature-sensitive that a rise of just a few degrees Celsius could in many places eventually produce entirely female offspring.
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That could wipe out whole populations. If temperatures climb too high, things actually get worse; eggs literally cook in their nests. Before the latest research, however, most studies suggested excessive feminization wouldn't pose a threat until late in the 21st century, and scant work had been done to examine what may be happening already.