Green sea turtles may stop basking on beaches around the world within a century due to rising sea temperatures, a new study suggests.
Naturalists as early as Darwin observed beach basking in green turtles (Chelonia mydas). It helps the threatened animals regulate their body temperatures and may help their digestion and immune systems.
After analysing six years of turtle surveys and 24 years of satellite data, researchers from Duke University, the National Oceanic and Atmospheric Administration (NOAA) Pacific Islands Fisheries Science Center and the University of Ioannina in Greece found the turtles bask less often when sea surface temperatures rise.
If global warming continues, they may stop basking altogether by 2102. Or even earlier in some places like Hawaii where you might stop seeing turtles sunning themselves on the beach in less than 25 years.
The cut-off point for Green Turtles is 23 °C at the sea surface. Warmer than this and they don’t need to get out to get warm.
Not all green turtles bask on land. Though the turtles are found in tropical and subtropical oceans around the world, beach basking has only been observed in Hawaii, the Galapagos Islands and Australia. Sea surface temperatures at these sites have been observed to be warming at three times the global average rate.
It is not yet clear whether populations that currently bask on land during cooler months will adapt to warming sea temperatures and begin to bask exclusively in the water, as do some other populations around the world.
Terrestrial basking sea turtles are responding to spatio-temporal sea surface temperature patterns, Kyle S. Van Houtan, John M. Halley, and Wendy Marks. Biology Letters, January 14, 2015. DOI: 10.1098/rsbl.2014.0744
Photo credit: Tim Nicholson