Profile cover photo
Profile photo
Nicos Paroutis
3 followers
3 followers
About
Communities and Collections
View all
Posts

Post has attachment

Post has shared content
Loggerhead turtles home in on nests magnetically
Female turtles find their way back to nesting beaches by looking for unique magnetic signatures along the coast, according to a new study published in Current Biology.

Loggerhead turtles, for example, leave their natal beaches as hatchlings and traverse entire ocean basins before returning to nest, at regular intervals, on the same stretch of coastline where they were born. How sea turtles accomplish this natal homing has remained an enduring mystery until now.

Several years ago, Kenneth Lohmann, the co-author of the new study, proposed that animals including sea turtles and salmon might imprint on magnetic fields early in life, but that idea has proven difficult to test in the open ocean.

In the new study, Brothers and Lohmann took a different approach by studying changes in the behavior of nesting turtles over time. The researchers analysed a 19-year (1993–2011) database of loggerhead nesting sites on the Atlantic coast of Florida, an area encompassing the largest sea turtle rookery in North America.

Their analyses confirmed the predictions of the geomagnetic imprinting hypothesis. In some times and places, the Earth's field shifted so that the magnetic signatures of adjacent locations along the beach moved closer together. When that happened, nesting turtles packed themselves in along a shorter stretch of coastline, just as the researchers had predicted.

In places where magnetic signatures diverged, sea turtles spread out and laid their eggs in nests that were fewer and farther between.

Turtles are long lived, and females undertake reproductive migrations periodically throughout their adult lives. Thus, the population of turtles that migrate to a given beach to nest each year consists of two subsets: a group of first-time nesters, and another, typically larger group of older “re-migrants” that have nested in the area during previous years.

Sea turtles likely go to great lengths to find the places where they began life because successful nesting requires a combination of environmental features that are rare: soft sand, the right temperature, few predators, and an easily accessible beach.
http://news.scubatravel.co.uk/loggerhead-turtles-home-nests-magnetically.html
#turtle   #science   #marinebiology  
photo credit: Matt Kieffer [CC BY-SA 2.0]
Photo

Post has shared content
Warming seas stop green turtles basking
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 under 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.
Photo: Tim Nicholson
http://news.scubatravel.co.uk/warming-seas-stop-turtles-basking.html
#turtle   #science   #marinelife  
Photo

Post has attachment
Photo

Post has attachment

Post has attachment

Post has attachment

Post has attachment

Post has attachment
Wait while more posts are being loaded