Made In The Shade
Artificial shade could help ensure survival of male sea turtles
Male sea turtles can’t take the heat. Warmer temperatures cause turtle eggs to produce females – leading to concerns that global warming could wipe out mates. A new study from Central America, however, suggests that a few sheets of plastic could help one highly endangered species produce some pretty cool guys.
Among “marine turtles, sex is determined by incubation temperature, such that warming temperatures could lead to a higher production of female hatchlings,” a research team reports in Global Change Biology. Exactly how climate change could affect this key piece of turtle reproduction isn’t well understood, however. To fill in some of the gaps, the researchers studied the link between temperature and sex at Caribbean beaches in Colombia and Panama where critically endangered Leatherback sea turtles dig nesting holes and lay their eggs.
For three breeding seasons – in 2005, 2006 and 2007 – the team buried sensors in the sand at different depths, recording temperatures every 30 minutes. Then, they compared how temps compared to the sex of hatchling turtles. Overall, they estimated that about 92% of the turtles hatching from the nests were females.
Next, the researchers plugged their data into forecasts of future beach temperatures, based on global climate models. The results weren’t encouraging: Within a decade, they found, warming could produce “complete feminization” of hatchlings.
But there was a bit of hope for the boys; small, “male-producing refugia” could hang on in the cooler parts of some nests, in nests dug in cooler parts of some beaches, or in nests dug on beaches that have sand that doesn’t warm up so much. To save males, “these natural refugia could be assigned preferential conservation status,” the researchers note.
But what if saving bisexual beaches isn’t enough? To see if there was a way for conservationists to make sure that at least some eggs were cool enough to produce males during a criticial developmental period, the researchers tried erecting black plastic sun shields over some nests. The artificial shade “was effective in reducing nest temperature [and] producing a higher proportion of male hatchlings, without compromising the fitness or hatching success.”
The findings suggest a two-step strategy, the authors conclude. First, “conservation managers could establish priorities based on the impacts and threats present in each breeding area to preferentially conserve male producing beaches and nests.” In “extreme” situations, however, “manipulation of the incubation temperatures of some nests to ensure that they” produce males may be necessary as “an emergency response to the severe impacts of climate change.” – David Malakoff | August 28, 2011
Source: Juan Patino-Martinez et al. (2011). A potential tool to mitigate the impacts of climate change to the caribbean leatherback sea turtle. Global Change Biology doi: 10.1111/j.1365-2486.2011.02532.x
Image © Steven Francis | Dreamstime.com
