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Turtle
migration directly influenced by drift experiences with ocean currents as
hatchlings
Date:
May 14, 2014
Source:
University of Southampton
Summary:
New research has found that adult sea-turtle
migrations and their selection of feeding sites are directly influenced by
their past experiences as little hatchlings adrift in ocean currents. When they
breed, adult sea turtles return to the beach where they were born. After
breeding, adult sea turtles typically migrate several hundreds to thousands of
kilometres to their feeding habitats. However, there has been little
information about how turtles chose their feeding sites.
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New research has found that adult sea-turtle migrations and
their selection of feeding sites are directly influenced by their past
experiences as little hatchlings adrift in ocean currents.
When they
breed, adult sea turtles return to the beach where they were born.. After
breeding, adult sea turtles typically migrate several hundreds to thousands of
kilometres to their feeding habitats. However, there has been little
information about how turtles chose their feeding sites. For example, some
turtles migrate to feeding habitats thousands of kilometres away, while other
turtles don't migrate or feed in the open ocean.
The study,
which involves the University of Southampton, looked at what habitats the
turtles would have experienced as juveniles. New-born hatchling sea turtles are
too small to track with satellite tags. However, when they emerge from their
eggs, they head to the ocean and drift with ocean currents to their juvenile
development habitats. The researchers combined all the available satellite
tracking data on adult turtles with models of how the world's sea water moves
past nesting sites to study where the hatchling sea turtles drift to.
By comparing
global patterns in the migrations of all satellite tracked sea turtles with
global hatchling drift patterns, they showed that adult sea turtle migrations
and foraging habitat selections were based on their past experiences drifting
with ocean currents.
Dr Rebecca
Scott, who led the study soon to be reported in the journal Ecology,
says: "Hatchlings' swimming abilities are pretty weak, and so they are
largely at the mercy of the currents. If they drift to a good site, they seem
to imprint on this location, and then later actively go there as an adult; and
because they're bigger and stronger they can swim there directly,"
explained Dr Scott, who is based at the GEOMAR Helmholtz Centre for Ocean
Research in Kiel, Germany.
"Conversely,
if the hatchlings don't drift to sites that are suitable for adult feeding, you
see that reflected in the behaviour of the adults, which either do not migrate
or they feed in the open ocean, which is not the normal strategy for most turtle
species."
Many animal
groups undertake great migrations, and the process of learning where to go on
these travels can take several forms. For example, some juvenile whales and
birds learn migration routes by following their mothers or more experienced
group members, whilst other bird and insect species see to be born with the
information or a map sense that informs them where they should migrate.
However,
neither of these strategies works for turtles. Once the adult female has laid
her eggs on a beach, her involvement in her offspring's development ends. When
the hatchlings crawl down the beach into the water, they are on their own;
there is no experienced turtle to follow, and they go where the ocean takes
them.
Dr Bob Marsh
from the University of Southampton, who was Dr Scott's supervisor and co-author
of the study, said: "Although it is known that ocean currents have a large
influence on the dispersion of small planktonic organisms, these findings
reveal ocean currents also directly shape some the migrations of some of the
largest, most powerful long distance migrants in the animal kingdom."
Story
Source:
The above
story is based on materials provided by University of Southampton. Note: Materials may be
edited for content and length.
Journal
Reference:
- Rebecca Scott, Robert Marsh, Graeme Hays. Ontogeny of long distance migration. Ecology, 2014; 140425082009005 DOI: 10.1890/13-2164.1
Cite This
Page:
University of Southampton.
"Turtle migration directly influenced by drift experiences with ocean
currents as hatchlings." ScienceDaily. ScienceDaily, 14 May 2014.
<www.sciencedaily.com/releases/2014/05/140514084554.htm>.