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Using ocean circulation models to explore factors influencing variability in hatchling sea turtle dispersal
Title
Using ocean circulation models to explore factors influencing variability in hatchling sea turtle dispersal.
Author
DuBois, Morgan Jaime
Abstract/Description
When sea turtles hatch, they journey offshore to the open ocean. Currents are one of the factors that influence the success of this journey. The spatial ecology influencing hatchling turtles must be evaluated to protect them most effectively. Here, I examine how spatial, temporal, and climatological factors impact the dispersal of turtle hatchlings via ocean currents. I use the HYCOM global model combined with the Ichthyop particle simulator to measure the current driven dispersal of sea...
Show moreWhen sea turtles hatch, they journey offshore to the open ocean. Currents are one of the factors that influence the success of this journey. The spatial ecology influencing hatchling turtles must be evaluated to protect them most effectively. Here, I examine how spatial, temporal, and climatological factors impact the dispersal of turtle hatchlings via ocean currents. I use the HYCOM global model combined with the Ichthyop particle simulator to measure the current driven dispersal of sea turtles. In a global analysis, spatial traits are a key factor driving dispersal. Annual variability in ocean currents also impact how far turtles can go. The differences in dispersal distance expand across sites and years the longer the turtles are in the water. I also evaluated the spatiotemporal variability in dispersal distance for the Gulf of Mexico endemic Kemp's Ridley sea turtle (Lepidochelys kempii) and related that variability to the frequency and severity of hurricanes. There are important spatiotemporal differences in dispersal that suggest varying levels of hatchling dispersal for each rookery. Further, increased frequency and intensity of hurricanes decreases the dispersal of hatchlings in the Gulf of Mexico. These findings can assist in model building and conservation planning for sea turtles worldwide.
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Date Issued
2020, 2020
Identifier
1201541370, WFE0000711
Format
Document (PDF)
Piloting the use of stereo-video cameras to develop a non-invasive in-water index of juvenile sea turtle length distributions in the Bahamas and the northern Gulf of Mexico
Title
Piloting the use of stereo-video cameras to develop a non-invasive in-water index of juvenile sea turtle length distributions in the Bahamas and the northern Gulf of Mexico.
Author
Siegfried, Tabitha Renee
Abstract/Description
The northern Gulf of Mexico (nGOM) from the Panhandle to the Big Bend areas of Florida have had few studies that assess sea turtle population dynamics in-water. This study aimed to expand sea turtle research within this geographic region by collecting in situ data on sea turtles using a stereo-video camera system (SVCS). First, the accuracy of a SVCS to measure straight carapace length (SCL) of sea turtles in the Bahamas and Florida was assessed. To achieve this, 63 juvenile, subadult, and...
Show moreThe northern Gulf of Mexico (nGOM) from the Panhandle to the Big Bend areas of Florida have had few studies that assess sea turtle population dynamics in-water. This study aimed to expand sea turtle research within this geographic region by collecting in situ data on sea turtles using a stereo-video camera system (SVCS). First, the accuracy of a SVCS to measure straight carapace length (SCL) of sea turtles in the Bahamas and Florida was assessed. To achieve this, 63 juvenile, subadult, and adult sea turtles across three species, were hand-captured and measured. Mean percent bias of stereo SCL ranged from -0.61% (± 0.11 SE) to -4.46% (± 0.31 SE) across all species. SVCS was then used to assess the population structure within the nGOM. Results show that artificial reefs are serving as developmental habitats for juvenile Chelonia mydas, while also supporting sub-adult and adult Caretta caretta and juvenile Lepidochelys kempii. This indicates that the coastal waters of the nGOM should be considered an important habitat for sea turtle populations and should be prioritized for research. Establishing novel, non-invasive methodologies to collect data on abundance, size distribution, and habitat use of sea turtles, can help improve conservation status assessments.
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Date Issued
2020, 2020
Identifier
1233040286, WFE0000740
Format
Document (PDF)
Growing pains
Title
Growing pains: investigating satellite tag epoxy attachments on juvenile turtles.
Author
Vidal, Alexander
Abstract/Description
While nesting behavior of sea turtles is well understood, gaps in knowledge exist for inwater movements. This is especially true for neonate and small juvenile turtles, which are overall data poor at pelagic and early neritic stages. The use of satellite-linked platform terminal transmitters (PTTs) allows scientists to study sea turtle movements; however, long-term tracking of sea turtles comes with a unique set of challenges. Tracking durations can be brief and limited by technical failures....
Show moreWhile nesting behavior of sea turtles is well understood, gaps in knowledge exist for inwater movements. This is especially true for neonate and small juvenile turtles, which are overall data poor at pelagic and early neritic stages. The use of satellite-linked platform terminal transmitters (PTTs) allows scientists to study sea turtle movements; however, long-term tracking of sea turtles comes with a unique set of challenges. Tracking durations can be brief and limited by technical failures. Most PTTs on small juveniles fail within one year. There is a general consensus among many biologists who tag small juvenile turtles that tags are failing due to premature detachment from carapace expansion. I tested this growth-caused detachment hypothesis through a series of controlled experiments. First, using empty red-eared slider (Trachemys scripta elegans) shells, I conducted axial load testing with model transmitters attached. Second, using juvenile red-eared sliders with model PTTs, I recreated the stress of shell growth on the epoxied-tag attachment. In both experiments, a suite of epoxies were tested, expansion factors were measured, and data was compared to sea turtle growth rates. This research contributes to the knowledge of how adhesives interact with a growing turtle shell.
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Identifier
1294313663, WFE0000769
Format
Document (PDF)