The life
of a sea turtle begins as it hatches within the buried sand and instinctively
sprints into the water amidst a gauntlet of predators. But many survive... then vanishes, their movements secretly held by the
vast ocean.
Depending
on the species, a sea turtle spends 1-15 years in the open sea, the so-called ‘lost
years’ — the period that ensues after the turtles break free from their eggs to
reach the open ocean until the time they come back as large juveniles to their
feeding grounds near coastlines. Scientists find it critical to understand this
because it serves as the foundation of sea turtle populations. Sea turtles live
long lives so understanding this missing part of their ‘biography’ and the
threats they may encounter is important to inform conservation efforts and
guide policies.
According
to Katherine Mansfield, who has studied turtles for more than 20 years, the
challenge in completing the turtles’ biographies is that it’s just difficult to
survey an entire ocean.
But they
did it.
 |
| Figure from Mansfield et al. (2014) |
She and
her team of researchers from the University of Central Florida fit 17 newborn
loggerheads with tiny satellite tags. It took them a long time to perfect this.
What they realized is that turtle’s shells are made of keratin (as our
fingernails are). So what they did is seek a collaborator’s manicurist, and, with her brilliant idea, they were able to fit the satellite tags using
an acrylic base coat that seals the shell from peeling. The tags lasted for
more than 7 months.
These
efforts produced a map which clearly shows the movements of loggerheads for 27
to 220 days.
What
Mansfield found out is that the basic overall pattern of movement of
loggerheads coincides with previous knowledge, but there were significant
nuances in the path each individual turtle takes.
For
instance, contrary to common knowledge that turtles go straight and fast to the
North Atlantic Gyre (and they’re mostly right), it turns out they took their
time running in local circles, even taking them away from the gyre to the
Sargasso Sea.
Sargassum, a type of brown algae, is a favorable habitat for baby turtles since it provides shelter against predators. It's also a haven for the cold-blooded turtles because the warmer waters of the seaweed-filled surface allow them to grow faster and reach sexual maturity earlier.
Sargassum, a type of brown algae, is a favorable habitat for baby turtles since it provides shelter against predators. It's also a haven for the cold-blooded turtles because the warmer waters of the seaweed-filled surface allow them to grow faster and reach sexual maturity earlier.
Unraveling clues where baby turtles go during their 'lost years' and have it mapped out has been a feat for Mansfield and her team. There are more questions though. So after 5
years, she and a large team of researchers took it a notch
higher.
They
developed a computer model that predicts where sea turtle hatchlings go after
they leave Florida's shores.
That's
for our next blog.
Stay
tuned.
________
Mansfield, K. L., Wyneken, J., Porter, W. P., & Luo, J.
(2014). First satellite tracks of neonate sea turtles redefine the ‘lost years’
oceanic niche. Proceedings of the Royal Society B: Biological Sciences, 281(1781),
20133039.
Putman, N. F., Seney, E. E., Verley, P., Shaver, D. J., López‐Castro, M. C., Cook, M., ... & Peña, L. J. (2019). Predicted distributions and abundances of the sea turtle ‘lost years’ in the western North Atlantic Ocean. Ecography 42:1-12.
Putman, N. F., Seney, E. E., Verley, P., Shaver, D. J., López‐Castro, M. C., Cook, M., ... & Peña, L. J. (2019). Predicted distributions and abundances of the sea turtle ‘lost years’ in the western North Atlantic Ocean. Ecography 42:1-12.
Science Daily (2019 Dec 23). Where do baby sea turtles go? New research technique may provide answers. Retrieved from http://bit.ly/37Mpcls
Yong, Ed. (2014 Mar 4). Where do Baby Turtles Go During Their Lost Years? Retrieved from https://on.natgeo.com/2uM5K9I
