Speaker 1: Welcome to brain stuff from how stuff works, Hey, brain
Speaker 1: stuff loin vocal bomb here. Australia's Great Barrier Reef is
Speaker 1: an enormous climate change experiment that's not happening in the
Speaker 1: safe isolation of a laboratory. Instead, the warming waters off
Speaker 1: the east coast of the continent have a profound real
Speaker 1: world effect on thousands of miles of coral as well
Speaker 1: as the animals that live there. For decades, scientists have
Speaker 1: suspected that increases in ocean's temperatures would affect sex ratios
Speaker 1: in certain animals, and research shows that's exactly what's happening
Speaker 1: to the Pacific Green Sea turtles. In most of Earth's creatures,
Speaker 1: gender is determined during the fertilization process. That's not true
Speaker 1: of animals like turtles, crocodiles, and alligators, though, which rely
Speaker 1: on a concept called temperature dependent sex determination, or TDS
Speaker 1: to dictate these sex of their offspring. In the case
Speaker 1: of turtles, warming waters and sands are altering the TDS
Speaker 1: process during the breeding season. The turtles, which can grow
Speaker 1: to nearly five hundred pounds that's about two ms, with
Speaker 1: a shell diameter of four feet or one point two meters,
Speaker 1: flop ashore and bury their eggs in the sand. The
Speaker 1: temperature of that sand determines whether baby turtles will wind
Speaker 1: up with blue or pink flippers. Figuratively speaking, if the
Speaker 1: incubation temperature is below eighty two degrees fahrenheit or thirty
Speaker 1: degrees celsius, the turtles will hatch as males. Above eighty
Speaker 1: eight degrees fahrenheit or thirty one degree celsius, the babies
Speaker 1: will be female. A similar problem has been reported in
Speaker 1: loggerhead turtles on Florida beaches, since scientists have noticed a
Speaker 1: strong bias toward female turtles in some instances. Up to
Speaker 1: to see how varying temperatures might affect turtle populations, scientists
Speaker 1: compared sex ratios of turtles near multiple breeding grounds around
Speaker 1: the Great Barrier Reef. They used blood tests and laparoscopy
Speaker 1: to determine the sex of these animals. At the southern
Speaker 1: edge of the reef, near Brisbane water, temperatures are cooler
Speaker 1: and female turtles out number males by a ratio of
Speaker 1: two to one, about sixty five to sixty nine percent female. However,
Speaker 1: about one thousand, two hundred miles north, in the largest
Speaker 1: and most critical sea turtle rookery in the Pacific Ocean.
Speaker 1: Warmer sea and air temperatures are having a dramatic effect
Speaker 1: of hatchlings are female. Although each male can mate with
Speaker 1: more than one female during a breeding season, a severe
Speaker 1: imbalance in sex ratios doesn't bode well for temperature sensitive
Speaker 1: species like sea turtles. Furthermore, once the incubating sand becomes
Speaker 1: too warm, it outright kills the developing organism, further threatening
Speaker 1: turtle populations. The study was published in January in the
Speaker 1: journal Cell Biology. The researchers write, our study highlights the
Speaker 1: need for immediate management strategies aimed at lowering incubation temperatures
Speaker 1: at key rookeries to boost the ability of local turtle
Speaker 1: populations to adapt to the changing environment and avoid a
Speaker 1: population collapse or even extinction. Today's episode was written by
Speaker 1: Nathan Chandler and produced by Tristan McNeil. For more on
Speaker 1: this and lots of other environmental topics, visit our home planet,
Speaker 1: how stuff Works dot com.