scholarly journals Orientation behaviour of leatherback sea turtles within the North Atlantic subtropical gyre

2015 ◽  
Vol 282 (1804) ◽  
pp. 20143129 ◽  
Author(s):  
Kara L. Dodge ◽  
Benjamin Galuardi ◽  
Molly E. Lutcavage
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Sensory Information ◽  
Subtropical Gyre ◽  
Dermochelys Coriacea ◽  
Male Adult ◽  
The North ◽  
The North Atlantic ◽  
Leatherback Sea Turtles ◽  
Nesting Beaches

Leatherback sea turtles ( Dermochelys coriacea ) travel thousands of kilometres between temperate feeding and tropical breeding/over-wintering grounds, with adult turtles able to pinpoint specific nesting beaches after multi-year absences. Their extensive migrations often occur in oceanic habitat where limited known sensory information is available to aid in orientation. Here, we examined the migratory orientation of adult male, adult female and subadult leatherbacks during their open-ocean movements within the North Atlantic subtropical gyre by analysing satellite-derived tracks from fifteen individuals over a 2-year period. To determine the turtles' true headings, we corrected the reconstructed tracks for current drift and found negligible differences between current-corrected and observed tracks within the gyre. Individual leatherback headings were remarkably consistent throughout the subtropical gyre, with turtles significantly oriented to the south-southeast. Adult leatherbacks of both sexes maintained similar mean headings and showed greater orientation precision overall. The consistent headings maintained by adult and subadult leatherbacks within the gyre suggest use of a common compass sense.

Estimating the age of juvenile loggerhead sea turtles in the North Atlantic

1997 ◽  
Vol 75 (1) ◽  
pp. 40-46 ◽  
Author(s):  
G. C. Hays ◽  
R. Marsh
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Drift Time ◽  
Loggerhead Sea Turtles ◽  
The North ◽  
The United Kingdom ◽  
The North Atlantic ◽  
Area North ◽  
Using Data ◽  
Nesting Beaches

Analysis of previously published records shows that the modal size of juvenile loggerhead sea turtles (Caretta caretta) found around the United Kingdom (the area north of 49°N and east of 12°W) is a carapace length of 20.5 cm. These turtles are believed to originate from nesting beaches in North America (principally Florida). We estimated their trans-Atlantic drift time using data from satellite-tracked buoys and from a mathematical model and, hence, estimated that the modal age of these juvenile turtles was between 1.80 and 3.75 years.

Plastic ingestion in oceanic-stage loggerhead sea turtles (Caretta caretta) off the North Atlantic subtropical gyre

2017 ◽  
Vol 121 (1-2) ◽  
pp. 222-229 ◽  
Author(s):  
Christopher K. Pham ◽  
Yasmina Rodríguez ◽  
Axelle Dauphin ◽  
Rita Carriço ◽  
João P.G.L. Frias ◽  
...  
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Caretta Caretta ◽  
Subtropical Gyre ◽  
Loggerhead Sea Turtles ◽  
The North ◽  
The North Atlantic

Lagrangian modeling of the active dispersal of juvenile leatherback turtles in the North Atlantic Ocean

2020 ◽  
Author(s):  
Philippe Gaspar ◽  
Maxime Lalire ◽  
Pierrick Giffard ◽  
Tony Candela
Keyword(s):  
North Atlantic ◽  
Sea Turtles ◽  
Sea Turtle ◽  
Juvenile Stage ◽  
Subtropical Gyre ◽  
Ocean Currents ◽  
Leatherback Turtles ◽  
The North ◽  
Active Dispersal ◽  
The North Atlantic

<p>It has long been assumed that young sea turtles drift passively with ocean currents. As a consequence, simple Lagrangian models have often been used to investigate the dispersal of various sea turtle populations during their juvenile stage. However, evidence is growing that juvenile sea turtles do not drift purely passively with ocean currents but also display some swimming activity, generally directed towards favorable habitats.</p><p>We have thus developed a new Sea Turtle Active Movement Model (STAMM) in which simulated individuals disperse under the combined influence of oceanic currents and swimming movements triggered by the need to find suitable habitats, that is areas with suitable water temperatures and sufficient food.  Preferred temperatures and food requirements are modeled to vary with the age (or size) of the simulated individuals.</p><p>STAMM is used here to investigate the active dispersal of juvenile leatherback turtles (Dermochelys coriacea) born in French Guiana, a major rookery for the Northwest Atlantic population. Our simulations reveal that:</p><ol><li> While currents broadly shape the dispersal area, habitat-driven movements profoundly structure the spatio-temporal distribution of juveniles within this area. Passive turtles can drift far North in deadly cold waters or concentrate in oligotrophic waters found at the center of the North Atlantic subtropical gyre. On the contrary, actively swimming juveniles tend to concentrate in favorable habitats along the northern boundary of the subtropical gyre and undertake seasonal north-south migrations allowing them to remain in suitable water temperatures.</li> <li>Active juveniles ultimately target rich areas of the Eastern Atlantic basin, in particular in the Bay of Biscay, off Galicia, Portugal and Mauritania, and in the western Mediterranean Sea where juvenile leatherbacks are actually observed. These zones are inaccessible to passive turtles.</li> <li>Arrival times of the active juveniles in these favorable zones are consistent with the observed sizes of individuals bycaught or stranded in these areas;</li> </ol><p>All together these results suggest that active habitat-driven swimming movements shall be systematically taken into account to produce realistic simulations of the spatial distribution of sea turtles during their pelagic juvenile stage. This is much needed to help develop effective conservation measures targeting this critical life stage.</p>

Changes across 66°W, the Caribbean Sea and the Western boundaries of the North Atlantic Subtropical Gyre

2018 ◽  
Vol 168 ◽  
pp. 296-309 ◽  
Author(s):  
M. Casanova-Masjoan ◽  
T.M. Joyce ◽  
M.D. Pérez-Hernández ◽  
P. Vélez-Belchí ◽  
A. Hernández-Guerra
Keyword(s):  
North Atlantic ◽  
Caribbean Sea ◽  
Subtropical Gyre ◽  
The North ◽  
The Caribbean ◽  
The North Atlantic

The spiralling North Atlantic Subtropical Gyre

2020 ◽  
Author(s):  
Kristofer Döös ◽  
Sara Berglund ◽  
Trevor Mcdougall ◽  
Sjoerd Groeskamp
Keyword(s):  
North Atlantic ◽  
Gulf Stream ◽  
Subtropical Gyre ◽  
The South ◽  
Spiral Flow ◽  
The North ◽  
Saline Waters ◽  
Downward Spiral ◽  
Meridional Overturning ◽  
The North Atlantic

<p>The North Atlantic Subtropical Gyre is shown to have a downward spiral flow beneath the mixed layer, where the water slowly gets denser, colder and fresher as it spins around the gyre. This path is traced with Lagrangian trajectories as they enter the Gyre in the Gulf Stream from the south until they exit through the North Atlantic Drift. The preliminary results indicate that these warm, saline waters from the south gradually becomes fresher, colder and denser due to mixing with waters originating from the North Atlantic. There are indications that there is also a diapycnal mixing, in the eastern part of the gyre due to mixing with the saline Mediterranean Waters, which would then be crucial for the Atlantic Meridional Overturning. The mixing in the rest of the gyre is dominated by isopycnic mixing, which transforms gradually the water into colder and fresher water as it spins down the gyre into the abyssal ocean before heading north.</p>

scholarly journals Surface Salinity in the North Atlantic Subtropical Gyre During the STRASSE/SPURS Summer 2012 Cruise

Oceanography ◽  
2015 ◽  
Vol 28 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Gilles Reverdin ◽  
◽  
Simon Morisset ◽  
Louis Marieé ◽  
Denis Bourras ◽  
...  
Keyword(s):  
North Atlantic ◽  
Subtropical Gyre ◽  
Surface Salinity ◽  
The North ◽  
The North Atlantic

scholarly journals Behaviour of leatherback sea turtles, Dermochelys coriacea , during the migratory cycle

2005 ◽  
Vol 272 (1572) ◽  
pp. 1547-1555 ◽  
Author(s):  
Michael C James ◽  
Ransom A Myers ◽  
C. Andrea Ottensmeyer
Keyword(s):  
Sea Turtles ◽  
Satellite Telemetry ◽  
Biological Significance ◽  
Dermochelys Coriacea ◽  
Behavioural Patterns ◽  
Nesting Behaviour ◽  
Migratory Cycle ◽  
Leatherback Sea Turtles ◽  
Migratory Patterns ◽  
Nesting Beaches

Leatherback sea turtles, Dermochelys coriacea , undertake broad oceanic movements. While satellite telemetry has been used to investigate the post-nesting behaviour of female turtles tagged on tropical nesting beaches, long-term behavioural patterns of turtles of different sexes and sizes have not been described. Here we investigate behaviour for 25 subadult and adult male and female turtles satellite-tagged in temperate waters off Nova Scotia, Canada. Although sex and reproductive condition contributed to variation in migratory patterns, the migratory cycle of all turtles included movement between temperate and tropical waters. Marked changes in rates of travel, and diving and surfacing behaviour, accompanied southward movement away from northern foraging areas. As turtles approached higher latitudes the following spring and summer, they assumed behaviours consistent with regular foraging activity and eventually settled in coastal areas off Canada and the northeastern USA. Behavioural patterns corresponding to various phases of the migratory cycle were consistent across multiple animals and were repeated within individuals that completed return movements to northern waters. We consider the potential biological significance of these patterns, including how turtle behaviour relates to predator avoidance, thermoregulation and prey distribution.

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