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Loggerhead
Sea Turtle (Caretta caretta) Satellite Tagging
ProjectSarah V. Mitchell, NOAA Gray's Reef National Marine Sanctuary Poster presented in Mazatlan '98--18th Annual Sea Turtle Symposium
Site Background
Gray's Reef National Marine Sanctuary (GRNMS) is one of the largest nearshore live-bottom reefs of the southeastern United States. As such it is an important habitat for sea turtles including the threatened loggerhead sea turtle. The ledges and overhangs of the reef provide the loggerhead sea turtle with protected resting spots, a bountiful resource of food, and close proximity to nesting sites on barrier island beaches. The National Oceanic and Atmospheric Administration (NOAA) manages Gray's Reef and the other national marine sanctuaries to protect their natural resources. For each sanctuary, a management plan is developed to encourage compatible public uses, and to promote scientific understanding and public awareness of the marine environment. Gray's Reef National Marine Sanctuary is located 32 kilometers (17.5 nautical miles) off Sapelo Island, Georgia and encompasses 58 square kilometers (17 sq. nautical miles) of live-bottom habitat.
Gray's Reef is a submerged hard bottom (limestone) area that, as compared to surrounding areas, contains extensive but discontinuous calcareous sandstone outcropping of moderate (3 meters) height with sandy, flat-bottomed troughs between. The series of rock ledges and sand expanses has produced a complex habitat of caves, burrows, troughs, and overhangs that provide a solid base for the abundant sessile invertebrates to attach and grow. This rocky platform with its carpet of attached organisms is known locally as a "live bottom habitat". This topography supports an unusual assemblage of temperate and tropical marine flora and fauna. Algae and invertebrates grow on the exposed rock surfaces: Dominant invertebrates include sponges, barnacles, sea fans, hard coral, sea stars, crabs, lobsters, snails, and shrimp.
Satellite transmitter tracking of male loggerheads captured at Gray's Reef National Marine Sanctuary, off the coast of Georgia, USA, necessitated a method of attachment that reduced the time of transmitter attachment and the risks to the animal. The length of time for the adhesive to cure, potential thermal reaction in the adhesive mixture, and reliability of transmitter attachment to the carapace were examined.
Assessment of several methods of attachment of transmitters led to the findings of two-part epoxy as a viable alternative to fiberglass. Use of epoxy significantly reduces the length of time of transmitter application compared to fiberglass. The attachment procedure typically requires less than 20 minutes when using epoxy as the adhesive. Fiberglass attachment of transmitters typically requires several hours (the time will vary and is dependent on environmental conditions such as temperature and humidity, as well as the ratio of catalyst added to the adhesive).
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PROCEDURE 
1) Clean Attachment Area:
- · Wash the carapace with seawater between each of the following steps
- · Scrape off barnacles with a plastic paint scraper
- · Scrub with a green scrubby
- · Sand with medium grit sandpaper
- · Dry area thoroughly
2) Attachment:
- · If the bottom surface of the transmitter is smooth, score opposing diagonal lines into the bottom surface of the transmitter with a semi-sharp object such as a screw driver or metal putty knife.
- · Set-up and prepare supplies
- · Have caulk gun loaded with 2-part Foil Fast® epoxy, and secure nozzle in place on gun.
- · Thoroughly mix 2 oz of Sonic Weld® by hand.
- · Roll the Sonic Weld® into 1 cm coils the following lengths ( these figures are formulated for transmitters that measure 7 X 14.5 cm on the bottom surface):
- · 2 coils that are each 18 cm long
- · 4 coils that are each 7 cm long
·
Place a 1 cm diameter by 18 cm long coil of thoroughly
mixed Sonic Weld® around the edge of the bottom of
the transmitter such that it covers 1/3 of a long side,
the entire short side and 1/3 of the following long side,
as shown in the drawing at right. This coil will form a
lip on the transmitter when it is mounted on the
turtle.- · Repeat with the other 1 cm diameter by 18 cm long coil of Sonic Weld® to the opposite end of the bottom of the transmitter (again 1/3 long side - entire short side - 1/3 long side).
- · Attach one coil 7 cm long (1 cm in diameter) to each of the 4 coil ends that you have just placed on the transmitter. Leave these ends hanging free at this point.
- · Completely cover the entire bottom of the transmitter with a generous amount of Foil Fast®.
- · Place the transmitter in the correct position
on the turtle and press the transmitter firmly against
the carapace.
- · Excess Foil Fast® will discharge as the transmitter is placed on the turtle from the 2 openings on the long sides in areas where there is an absence of Sonic Weld®. If Foil Fast® does not flow outside from the bottom of the transmitter, remove the unit and apply additional Foil Fast® to transmitter and reapply onto carapace.
- · Press the lip coils of Sonic Weld® securely in place against the carapace. Press the 4 loose pieces of Sonic Weld® into the carapace forming a triangle on each side on the transmitter as shown in the drawing (The transmitter forms one of the sides of the triangle, the other two sides are formed by the 7 cm long coils.)
- · Fill in the triangle formed by the Sonic Weld® on each side of the transmitter with Foil Fast®.
- · The epoxy will set in 7 to 8 minutes.
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Project Objectives:
The objectives of this project are to monitor:
Methodology:
Although observations by sanctuary staff have documented the presence of various size and age groups of loggerhead sea turtles within the sanctuary and along the South Atlantic Bight, little is known about the turtle's daily and seasonal behavior or their use of the ocean habitats, especially off the coast of Georgia. Many studies have focused on nesting behavior and post nesting movement of adult females, while little work has been conducted on adult male and juvenile behavioral patterns and spatial use of coastal waters.
GRNMS Sea Turtle Satellite Tagging Project utilizes backpack satellite tags to monitor adult and juvenile loggerhead sea turtle behavior and movement in the South Atlantic Bight. Specifically, parameters including turtle's position, time, and depth are electronically collected and transmitted via satellite to scientists at GRNMS. The data allow scientists to 1) help explain movement and dive patterns of loggerhead sea turtles, 2) develop a biological model to increase the predictability of these patterns, and 3) obtain information concerning loggerhead behavior and activity off the coast of Georgia.
The loggerhead turtle has an elongate, heart shaped shell
that is ridged and made of two layers. The first layer is a
bony structure formed by the fusion of vertebrae and ribs,
while the second is a covering of keratinized scales or
scutes (similar to our finger and toe nails) which make up
the outer shell layer. The shell of the loggerhead turtle,
is called a carapace. For this study the satellite
transmitters will be attached to the turtle using a new
2-part adhesive placed on the highest part of the animal's
carapace, the second vertebral scale. A sea turtle, like all
reptiles, must surface to breath and when it does an air
bubble forms under its shell producing positive buoyancy,
bringing the animal to the surface in a flat, prone
position, rather than head first. As a result, the
transmitter antenna is placed facing backwards so when the
turtle surfaces, so too will the transmitter. As the turtle
and transmitter are exposed to air, the data collected while
underwater is transmitted via satellite.
Tagging Nesting Turtles
For this study, three nesting female loggerhead sea
turtles were 
captured
on Wassaw and Blackbeard Island beaches. Both islands are
part of the US. Department of the Interior National Wildlife
Refuge System.
Tagging Offshore Turtles
NOAA vessels are utilized to capture adult male loggerhead sea turtles at GRNMS. To capture a loggerhead offshore, a turtle is directed by NOAA divers into a hand held net, carried to the surface, and lifted onto a boat (boat lift and net were designed by the author, Gray's Reef National Marine Sanctuary). The turtle is returned to the capture site after the transmitter has been attached and the adhesive has set.
Preliminary Results:
The two-part epoxy method of attachment for satellite transmitters has proven successful in this study. Transmitters attached with this method have remained attached, delivering information, via satellite, from the turtles for eight months.
Research at GRNMS:
The Gray's Reef National Marine Sanctuary Management Plan outlined strategies for the effective management of the area's resources. A stated goal of the plan is to promote and coordinate research to enhance scientific understanding of the sanctuary and improve management decision making. A main objective to achieve this was implementation of a resource studies plan based on existing knowledge of live bottom ecosystems and evolving management issues.
The Gray's Reef National Marine Sanctuary recognizes the importance of long term monitoring to understand and recognize the health and status of the significant resources found in the sanctuary. Long term monitoring of the resources also serves the management concerns of other state and federal agencies as Gray's Reef is one of the largest natural live-bottom reefs in the South Atlantic Bight and serves as a good indicator of overall live bottom health in this region.
Acknowledgements: