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Sea turtle biology & conservation

Sea turtle biology & conservation - THE BIOLOGY&...

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Unformatted text preview: THE BIOLOGY & CONSERVATION OF SEA TURTLES Michelle Johnston – Dept. of Env. Health Sciences – Ph.D. Candidate – Sept. 9, 2008 “If the world goes on the way it is going, it will be a world without sea turtles. Some people accept this calmly, but I mistrust the prospect. Sea turtles are part of the old wilderness of the Earth, the hormones that make him human. If we let sea turtles go it is a sign we are ready to let all wilderness go. When that happens we shall no longer be exactly human.” human.” ~ Dr. Archie Carr What is a Sea Turtle Sea turtles are large, air breathing reptiles that live in subtropical and tropical waters subtropical around the world. They belong to the class Reptilia, which also encompasses snakes, lizards, Reptilia crocodiles, and dinosaurs, their ancient relatives! Millions of years ago, reptiles were one of the first animals to live on land, away form water. Many reptilian characteristics result from these animals adapting to land. Reptilian characteristics include: 1. Vertebral or spinal column – Because reptiles are vertebrates, just like birds and mammals, they must have a vertebral column to support their body weight on land. land. 2. Scales – Scales, or scutes, aid in armoring the body and preventing water loss. scutes 3. Air Breathers – Reptiles are just like us, they need to breath air to survive. They do not have gills! 4. Cold-blooded – Reptiles have a three-chambered heart and are cold-blooded, or ectothermic. The Coldthreecoldectothermic external environment largely determines their body temperature. 5. Internal Fertilization – In other words, the sperm fertilizes the egg inside the female. Also, many reptiles, and all sea turtles, lay eggs. 1 Fossil Record Sea turtles appeared Sea in the fossil record around 200 million years ago Fossil records show the now Fossil extinct Archelon ischyros was Archelon one of the largest marine turtles that ever lived (13 ft.) Sea turtles, saltwater crocs, sea Sea snakes, and marine iguanas are the only surviving reptiles that depend on the sea Anatomy Extinction and why should I care? A threatened species is any species likely to become an endangered species within the near future. endangered Under the U.S. Endangered Species Act, an endangered species is “Any species which is in danger of extinction throughout all or a significant portion of its range.” A plant or animal becomes extinct when range.” the last living individual of that species dies, causing it to vanish from the planet forever. Plants and animals have been going extinct for millions of years; it is a natural part of evolution. years; Today, however, species are going extinct at a much faster rate than normal, mainly due to human impacts. Habitat destruction, over consumption, and pollution are just a few of the problems are decreasing the diversity of the life on earth. Much can be learned about the condition of the environment by looking at sea turtles. They are an looking indicator species – sea turtles travel all over the ocean, connect land and sea, and therefore, reflect the indicator and health of the earth. They have survived for over 200 million years, and if they are in trouble, then the years, ocean is in trouble, the earth is in trouble, and so are we! Suddenly, sea turtles are struggling to Suddenly, survive, largely because of the things people are doing to the ocean and the land. What does this mean ocean for us? 2 Why should we save sea turtles? Sea turtles add to the wildlife and biodiversity of our planet. They play an important role in the balance of the ocean’s ocean’ ecosystem. They are interconnected and an essential component in the ocean’s food web by keeping jellyfish and sea grass ocean’ populations under control. Beach Health Beach Medical uses Medical Indicator Species Indicator Sea Turtles of the World Kemp’s Ridley Kemp’ (Lepidochelys kempii) kempii) •Smallest of all sea turtles Physical Characteristics: •Status=Most endangered species! •Adults up to 80 pounds •Heart-shaped shell Heart- Nesting Characteristics: •Diurnal nesters •Arribadas •Rancho Nuevo, Mexico 3 Kemp’s Ridley Kemp’ (Lepidochelys kempii) kempii) History of Nesting Effort: •1947=40,000 females •1968=2,000 females •1980’s=200 females 1980’ •2002=1,000 females Nest Protection Efforts: •All nests moved to corral •Headstarting program •Beach protection •TED implementation Olive Ridley (Lepidochelys olivacea) olivacea) Nesting Characteristics: Status of Nesting Efforts: •Nocturnal nesters •Small subpopulations are recovering •Arribadas •Controlled harvest of eggs •Mainly Pacific Ocean •Black market for eggs Australian Flatback (Natator depressus) Physical Characteristics: •Status=Data deficient •Very flat shell Status of Nesting Efforts: •Stays in coastal waters around Australia •Nests 4 times/season with an average of 50 eggs per nest 4 Green Turtle (Chelonia mydas) Characteristics: •Status=Endangered •Green fatty tissue inside body Diet: •Hatchlings/Juveniles=omnivorous Threats: •Adults=strictly herbivorous •Poaching of meat for food •Jaw is serrated •Fibropapilloma Fibropapilloma Fibropapillomatosis, or commonly called FP, is a deadly tumor-forming disease that may be tumorlinked to pollution in the oceans and near shore waters. Fibropapilloma Fibropapilloma Hypothesis: foraging sea turtles (e.g. green sea turtles) Hypothesis: are being exposed to the benthic dinoflagellates that produce okadaic acid when they consume seagrass or macroalgae. macroalgae. The tumor-promoting toxin, okadaic acid, from The tumorbenthic dinoflagellates, such as Prorocentrum lima, Prorocentrum then cause the development of tumors. Prorocentrum Prorocentrum spp. use macroalgae and sea grass as substrate. When turtles feed on seagrass and macroalgae, they are macroalgae, consuming dinoflagellates and the okadaic acid toxin. 5 Black Turtle/East Pacific Green (Chelonia mydas agassizi) Physical Characteristics: •Status=Data deficient •Separate subspecies??? •DNA tests •Dark gray/black carapace •Narrow VS. Round carapace Leatherback Turtle (Dermochelys coriacea) Characteristics: Diet: •Status = Critically Endangered •Feed exclusively on jellyfish •Fleshy projections in throat to catch food •Leathery skin •10 feet in length •2,000 pounds •White longitudinal ridges Leatherback Turtle (Dermochelys coriacea) Fastest reptile Fastest (9.8 meters/sec) Deep divers (4,260 feet) Deep Adaptations: Adaptations: Shell Shell Pressure Pressure (oxygen, nitrogen) Counter shading Counter 6 Hawksbill Turtle (Eretmochelys imbricata) Characteristics: •Status=Endangered •Small with narrow head and beak •Brilliant patterns on carapace •Frequently seen around coral reefs Threats: •Feed on sponges, anemones, squid, and shrimp •Shell is used to make tortoiseshell jewelry, hair pins, boxes •Still trade market in Asia and Caribbean Loggerhead Turtle (Caretta caretta) Physical Characteristics: •Status=Threatened in US Endangered internationally •Large head compared to body size Diet: •Reddish brown carapace •Blue crabs •Yellowish head, neck, flippers •Whelks •Average length: 3 to 4 feet •Horseshoe crabs •Average weight: 250 to 350 pounds •Other Crustaceans Loggerhead Turtle (Caretta caretta) Shell Characteristics: • Carapace is made up of bony plates: 1. Marginal scutes 2. Inframarginal scutes 3. Medial scutes • Plastron made of plates • Vertebrae fused to shell 7 Loggerhead Turtle (Caretta caretta) Skull Characteristics: • Skull has seven cavities • Two cavities for ??? • One cavity for ??? • One cavity for ??? • Two cavities for ??? • One cavity for ??? Loggerhead Turtle (Caretta caretta) What is an Epibiont? Epibiont • Any type of organism that settles on the carapace, flippers, head, neck of a sea turtle Barnacles Hydrozoans COMMON TYPES: Tube Worms Barnacles Sea Squirts Polychaete Worms Skeleton Shrimp Dinoflagellates Leeches Bryozoans Loggerhead Life Cycle 8 Loggerhead Turtle (Caretta caretta) Reproduction: • •Nest every 2, 3, or more years Mate in water near natal nesting beach • Nesting Cycles: Late April-early May April- • Female mates with multiple males • Multiple paternity • Egg formation=2 weeks •Nest 4 to 6 times per season Loggerhead Turtle (Caretta caretta) Nesting: • Usually occurs at night • Emerges and crawls above high tide line • Digs body pit • Digs nest cavity using rear flippers • Nest cavity shaped like upside down light bulb • Nest cavity depth= 18 to 24 in. • Nest cavity width=10 in. 9 Loggerhead Turtle (Caretta caretta) Egg Deposition: • Contractions start and eggs drop from cloaca • Eggs drop 2-3 at a time 2- • Eggs size of ping pong balls and are soft and leathery • Mucous=antibacterial properties? • Average clutch size=120 eggs IS THIS TURTLE CRYING??? Loggerhead Turtle (Caretta caretta) Covering: • Fills in nest cavity with rear flippers • Uses front flippers to throw sand/wrack and camouflage nest • Circles entire body pit area to cover • Crawls back to ocean and will return to lay next clutch in 2 weeks weeks Loggerhead Turtle (Caretta caretta) Eggs: • Soft & leathery = Ability to dimple • 90% yolk and 10% albumin • Embryo develops 6-12 hours after egg 6deposition • Embryo develops under dimple • Dimple creates air pocket for gas exchange • Yolk provides nutrients to embryo during development 10 Loggerhead Turtle (Caretta caretta) Hatching: • Temperature plays important role in: 1. Length of incubation ( temp=faster; temp=slower) 2. Sex of hatchling (no X or Y chromosomes) 3. Sex ratio of clutch ( temp=females; temp=males) *Pivotal temperature for a 50:50 ratio of males to females is 29°C 29° Loggerhead Turtle (Caretta caretta) Hatchlings: • Hatchlings crack out of shell 45-60 45days after being laid • Use chipping tooth = caruncle • Group effort to hatch out=conveyor belt • Low oxygen levels in nest cavity • Takes 2 to 4 days to reach surface of sand • “Bowling” on surface indicates hatching Bowling” Photo credit, Zoe Bass, 2003 Loggerhead Turtle (Caretta caretta) Emergence and Journey to the Sea: • Usually emerge at night and head towards brightest horizon • Swimming frenzy for 24 to 48 hours • Swept up in Gulf Stream/North Atlantic Gyre • Spend 1-10 years in Sargasso Sea 1Sargasso then head around gyre again • Reach reproductive age at a minimum of 20 to 30 years 11 Threats to Sea Turtles Predatory Threats: • Ghost crabs (eggs & hatchlings) • Raccoons (eggs & hatchlings) • Ants (eggs & hatchlings) • Birds (hatchlings at sea) • Fish (hatchlings at sea) • Sharks (juveniles to adults) • Man (eggs and adults) Threats to Sea Turtles Man-Made Threats: ManArtificial Beachfront Lighting Artificial Coastal Development and Armoring Coastal Beach Alteration and Nourishment Beach Marine Debris and Pollution Marine Harvesting Harvesting Boating Boating Fishing Fishing Shrimp Trawling Shrimp ARTIFICIAL LIGHTS Man-made Threats: Man• Artificial lights • Coastal development • Beach renourishment • Beach armoring (sea walls, revetments, groins, etc.) •Deter nesting females • Marine pollution •Disorient emerging hatchlings • Commercial fishing efforts •Cause mortality • Recreational fishing efforts •Lighting ordinances for nesting beaches • Poaching of eggs and turtles for consumption •“Lights out for sea turtles!!” turtles!!” 12 COASTAL DEVELOPMENT: Renourishment, armoring, etc. Renourishment, Man-made Threats: Man• Artificial lights • Coastal development • Beach renourishment • Beach armoring (sea walls, revetments, groins, etc.) • Marine pollution • Commercial fishing efforts • Recreational fishing efforts • Poaching of eggs and turtles for consumption •Loss of critical nesting habitat •Sand compaction/soil content •Creating obstacles for successful nesting attempts MARINE POLLUTION: Man-made Threats: Man• Artificial lights • Coastal development • Beach renourishment • Beach armoring (sea walls, revetments, groins, etc.) • Marine pollution • Commercial fishing efforts • Recreational fishing efforts • Poaching of eggs and turtles for consumption •Dumping of trash •Ingestion by turtles •Non-point source pollution = loss of Nonwater quality = loss of foraging habitat = loss of turtles COMMERCIAL/RECRATIONAL FISHING EFFORTS: Man-made Threats: Man• Artificial lights • Coastal development • Beach renourishment • Beach armoring (sea walls, revetments, groins, etc.) • Marine pollution • Commercial fishing efforts • Recreational fishing efforts • Poaching of eggs and turtles for consumption 13 Long Line Fishery Shrimping Turtle Excluder Devices (TED’s) (TED’ • Designed by Sinky Boone, GA shrimper in 1980’s 1980’ • 97% effective in excluding turtles • Installed mid-way in net mid- • Turtle can escape net to get to surface to breathe • New 2003 TED regulations require SE shrimpers to pull Leatherback sized TED’s TED’ Conservation “Marine turtles have persisted for eons, prospering without protected areas, protected conservation laws, action plans, research manuals, and other accouterments of accouterments conservation programs. It is when people are involved, with over-exploitation and overhabitat perturbation, that biological conservation becomes essential.” essential.” J.G. Frazier, Smithsonian Institution 14 Conservation The management of sea turtles in the United States falls into two categories: the National Marine Fisheries Service is responsible for sea turtles in the marine environment and the Fish and Wildlife Service has jurisdiction over sea turtles on Service land. Because management responsibilities are spilt, people at all levels work together to preserve, or actively protect, sea turtles from danger. Problems? Conservation Beach Patrols Beach Nest Relocation (egg numbers) Nest Tagging Programs Tagging PIT (passive integrated transponder) PIT and Flipper Conservation Satellite Telemetry Satellite Importance? Importance? 15 Conservation Ecotourism Ecotourism Pritchards Island Pritchards Conservation Rehabilitation Rehabilitation Conservation Turn off beach lights! Turn No Plastic….ever! No Plastic… Stay off dunes Stay Don’t disturb nesting Don’ efforts Red Flashlights Red Volunteer Volunteer 16 THANK YOU!!! Sea Turtle Websites: •http://www.blueocean.org •http://www.dnr.sc.gov/seaturtle/index.htm •http://www.georgiaseaturtlecenter.org/ •www.seaturtle.org •www.seaturtlehospital.org •http://seamap.env.duke.edu/ 17 ...
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