Download or read book Assessing the Composition of Green Turtle Chelonia Mydas Foraging Grounds in Australasia Using Mixed Stock Analyses written by Michael Paul Jensen and published by . This book was released on 2010 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the population dynamics in both breeding and foraging habitats is a vital part of assessing the long-term viability of any species, especially those that are highly migratory. This is particularly true for green turtles, Chelonia mydas, which are long-lived marine turtles that undergo migrations for several years as post hatchlings until they select foraging grounds, and as adults, migrate between their foraging grounds and nesting beaches. Monitoring of populations at the foraging grounds may help detect early signs of population trends that would otherwise take decades to be observed at the nesting beach. In order to gain such insights the connectivity between nesting and foraging habitats must be established. Genetic analysis of rookeries to define discrete populations (stocks), in combination with Mixed Stock Analysis (MSA) based on data from molecular markers, provides an effective approach for estimating the origin of turtles sampled away from their nesting beach. In this thesis, new investigations into the genetic structure of green turtle populations in Australasia were conducted using longer (~780 bp) mitochondrial (mt) DNA sequences, larger sample sizes and new locations. This information provided the baseline data used in Mixed Stock Analyses of the composition of foraging grounds in three regions of Australasia including Western Australia, the Great Barrier Reef (GBR) and Malaysia. In chapter 2, I review what has been learned since the first MSA studies in marine turtles more than a decade ago. Since the early 1990s, numerous studies used this method to elucidate the rookery origins of young pelagic stage turtles and of older turtles in benthic foraging grounds, in fisheries by-catch and in strandings. These studies have all shown how Mixed Stock Analysis has provided valuable new insights into the distribution of marine turtles, although in most cases the estimates are affected by large uncertainty. Several issues in the effective use of MSA need to be addressed concerning study design, sample sizes and the resolution provided by the genetic marker. Nonetheless, Mixed Stock Analysis holds great potential for monitoring population trends at oceanic and coastal foraging grounds for all size classes. Comparisons of adults and juveniles provide an opportunity to pick up early signs of shifts in the contributions of populations that may indicate population decline (or increase) (e.g., Chapter 5). Recent increases in industrial development of coastal island and offshore habitats in Western Australia (WA) have highlighted the need to better understand the dynamics of marine turtle populations in these areas. An analysis of previously sampled populations (Management Units; MUs) and four new rookeries identified two possible new Management Units in this region at Cobourg Peninsula and Cocos (Keeling) Island and grouped Browse Island with the existing MU at Scott Reef and Barrow Island to the large North West Shelf MU. These analyses used a 780 bp sequence of the mtDNA control region that encompassed the 386 bp sequence used in a previous study. The longer sequence, larger sample sizes and new locations revealed more than doubled the number of haplotypes (n = 39) than previously observed. However, this made little difference to the population genetic structure as common haplotypes were still shared among population. MSA showed that the majority (>90%) of turtles foraging at Shark Bay were from neighbouring North West Shelf rookeries, while the Cocos (Keeling) foraging ground was composed of turtles mainly from Cocos (~70%), but with some contributions from North West Shelf and possibly Scott Reef MUs. In an investigation of foraging populations in Malaysia, mtDNA sequence data were analysed from 81 immature green turtles at two foraging grounds at Mantanani Island and Layang Layang Island located northwest of Sabah, Malaysia. Previously published data from 17 Australasian green turtle populations were used as the baseline data for tracing back the origin of turtles at the two foraging grounds. The majority of these turtles originated from major rookeries in the Malaysia and Philippine Turtle Islands (~30%), and Sarawak (~60%) in north-western Borneo. These same rookeries have a long tradition of using unshaded beach hatcheries that has resulted in the production of mostly female hatchlings. This may have contributed to the 1:4 female biases seen at the two foraging grounds. The implications of hatchery practises at nesting beaches are discussed and the importance of continued monitoring and research at these foraging areas is highly recommended to improve the management of marine turtles in the region. Detailed MSA of green turtle aggregations at six major foraging grounds along the east coast of Australian were combined with data from more than 30 years of mark–recapture efforts along the Great Barrier Reef. Overall, the MSA in combination with the mark-recapture data supports a model in which the foraging aggregations are composed of individuals from the two Great Barrier Reef stocks (nGBR, sGBR) with small contributions from other stocks. The north/south transect of foraging grounds analysed spanned ~2300 km. Along this transect the main contributor shifted from being predominantly the nGBR stock at foraging grounds in Torres Strait, Clack Reef and the Howicks Group to predominantly the sGBR stock at Edgecombe Bay, Shoalwater Bay and Moreton Bay. At the most northern foraging ground in the Torres Strait, significant shifts in haplotype frequencies between juveniles and adults resulted in major shifts in the estimated stock contributions for these groups. Fewer juveniles originated from the nGBR stock and higher proportion originated from the sGBR and „other‟ stocks in comparison to adults. This trend was apparent in the four most northern foraging grounds, even in Edgecombe Bay, which had a predominance of turtles from the sGBR stock. Point estimates of contributions from the nGBR stock dropped from 0.89 in adults to 0.53 in juveniles in Torres, Strait, from 0.69 to 0.49 at Clack Reef, from 0.66 to 0.49 in the Howicks Group and from 0.10 in adults to 0.01 in juveniles at Edgecombe Bay. In contrast, at the Shoalwater Bay foraging ground the opposite was observed, with a drop in contribution from the sGBR stock from 0.98 in adults to 0.84 and 0.85 in juveniles and sub-adults, respectively, and an increase in contributions from „other‟ stocks in juveniles and sub-adults. The observed patterns at the various foraging grounds likely resulted from several causes and four possible explanations are explored, the mostly likely of which were that (i) juveniles have shifted foraging grounds as they mature, or that (ii) reduced hatching success from the main nGBR rookery at Raine Island for more than a decade has resulted in reduced recruitment into the nGBR foraging ground. The later possibility suggests a need to take action to conserve the nGBR population The combined strength of data derived from mark-recapture studies, demographic studies to determine sex, maturity and breeding status of the turtles, genetic studies to determine stock composition and satellite telemetry, are needed to provide informed assessments of foraging populations necessary for guiding sustainable management of marine turtles.

Download or read book The Biology of Sea Turtles written by Jeanette Wyneken and published by CRC Press. This book was released on 2013-03-25 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the first volume of The Biology of Sea Turtles was published in 1997, the field has grown and matured in ways few of the authors would have predicted—particularly in the areas of physiology, behavior, genetics, and health. Volume III presents timely coverage of emerging areas as well as the integration of approaches and information that did not exist even a decade ago. The book assembles the foremost experts in each topic to provide the most up-to-date and comprehensive book on sea turtles available today. New areas covered include in vivo imaging of structure, spatial distributions of marine turtles at sea, epibiosis, imprinting, parasitology, and climatic effects. Life history is explored in three chapters covering age determination, predator-prey interactions, and mortality from bycatch. The Biology of Sea Turtles, Volume III will inspire scientists and students to explore and expand their understanding of these intriguing animals. The book provides clear baseline summaries, thoughtful syntheses, and effective presentation of the most fundamental topics spanning form and function, health, distributions, behavior, genetics, evolution, and ecology. Its scope and depth make it the definitive go-to reference in the field.

Download or read book Proceedings of the Twenty ninth Annual Symposium on Sea Turtle Biology and Conservation written by and published by . This book was released on 2012 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Juvenile Green Turtle Chelonia Mydas Foraging Ecology written by Eliza Inez Gilbert and published by . This book was released on 2005 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: For the endangered green turtle, Chelonia mydas, a fundamental component of recovery and conservation is an understanding of its foraging ecology. Foraging optimality models suggest animals will select resources of high quality over those of low quality. For green turtles, this behavior is important, as sufficient quantities of nutritionally adequate forage items are necessary for growth and reproduction. One intrinsic element in the understanding of green turtle foraging ecology is to identify and document the availability and quality of forage resources preferred by green turtles.

Download or read book Proceedings of the International Symposium on Sea Turtle Conservation Genetics 12 14 September 1995 Miami Florida written by Brian W. Bowen and published by . This book was released on 1996 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research and Management Techniques for the Conservation of Sea Turtles written by and published by . This book was released on 1999 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Identifying foraging and space use patterns of juvenile green sea turtles Chelonia mydas in Brewers Bay St Thomas using a fine scale positioning acoustic array written by Taylor Brunson and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: As green sea turtle (Chelonia mydas) populations in the Caribbean recover from historical overexploitation, growing environmental obstacles pose threats to the recovery of this species. The invasion of Halophila stipulacea seagrass in previously Syringodiumfiliforme and Halodule wrightii -dominated beds drastically alters the composition of green turtle foraging habitat. This change in forage supply for juvenile and adult green turtles in the Caribbean could impact their future habitat use and resource partitioning, information that conservation and management agencies use to implement protective guidelines for this species. We conducted a fine-scale tracking study of green turtles’ space use and movement patterns in Brewers Bay, St. Thomas to investigate their foraging selectivity in the mixed-species seagrass beds. The fine-scale positioning system(FPS) acoustic receiver array was deployed across ~1.5 km2 of the bay, which includes seagrass, coral reef, and sand/rock benthic habitat. Seventeen individual juvenile green sea turtles were tracked with acoustic transmitters with an estimated precision of ± 2meters. The native and invasive seagrass composition was mapped in the highest trafficked daytime area to pair with the turtles’ foraging locations. Turtles displayed typical diel patterns of movement with higher activity levels in shallow mixed-seagrass habitats during the day and lower activity levels in shallow reefs and rocky habitats at night. These movement results were linked to seagrass composition within the sampling grid using resource selection functions (RSF) to estimate turtle selection towards each seagrass species in Brewers Bay. Turtles were actively selecting the two native species, with no selection towards the invasive seagrass despite its high abundance. Interestingly, three individuals utilized foraging areas outside the sampling grid and in deeper water with monotypic invasive seagrass. This pattern of space use has not been observed in past tracking and observational studies in Brewers Bay, implying that part of this population has started modifying its foraging patterns to incorporate H. stipulacea.

Download or read book Sea turtles in the Mediterranean Distribution threats and conservation priorities written by Paolo Casale and published by IUCN. This book was released on 2010 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Evaluation of Seagrass Community Structure and Its Role in Green Sea Turtle Chelonia Mydas Forgaging Dynamics in the Lower Laguna Madre written by Tracy Fisher Weatherall and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Satellite tracking data of juvenile and subadult green turtles captured and released by Texas A & M University at Galveston's Sea Turtle and Fisheries Ecology Research Lab (STFERL) from the lower Laguna Madre indicate green sea turtles (Chelonia mydas) exhibit high fidelity to seagrass communities where they can be found year-round. Population growth is prerequisite to eventual down listing of this endangered species to a threatened status and its subsequent recovery. The role Texas' green turtle population will play in this recovery will depend, in part, on the ability of seagrass communities in the lower Laguna Madre to sustain continued growth of this population. Seagrass community structure was characterized during 7-8 March 2009 to determine if foraging grounds in the lower Laguna Madre can sustain green turtle population growth. Differences in seagrass community structure influencing foraging potential between high fidelity sites (Region 1) were compared to adjacent areas in which green turtles have not been captured and tracked by the STFERL (Region 2). Seagrass samples were taken from six seagrass communities to characterize seagrass and invertebrate community parameters. In addition, three standardized and randomized bag seine collections of nekton, invertebrates and plant debris were conducted within the six seagrass communities. Family richness and abundance of fishes and invertebrate fauna were assessed from the standardized bag seine collections. Seagrass species including Thalassia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass) were found in Region 1 whereas T. testudinum and H. wrightii were found in Region 2. Total seagrass biomass from Region 1 was significantly greater than that from Region 2 implying a healthier seagrass community. Seagrass beds in Region 2 were highly patchy and sparse. Family richness and faunal density collected with the bag seine in Region 1 were significantly higher than those in Region 2 suggesting seagrass habitat complexity was higher in Region 1. These data suggest a trend toward increased seagrass habitat quality and community complexity in Region 1 which, in turn, may contribute to a healthier seagrass environment that serves as an optimal foraging area for green turtles in the lower Laguna Madre.

Download or read book Biology of Australasian Frogs and Reptiles written by Gordon Clifford Grigg and published by . This book was released on 1985 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Marine Turtles in the Great Barrier Reef World Heritage Area written by Kirstin Dobbs and published by . This book was released on 2001 with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Leatherback Turtle written by James R. Spotila and published by JHU Press. This book was released on 2015-10-30 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most comprehensive book ever written on leatherback sea turtles. Weighing as much as 2,000 pounds and reaching lengths of over seven feet, leatherback turtles are the world’s largest reptile. These unusual sea turtles have a thick, pliable shell that helps them to withstand great depths—they can swim more than one thousand meters below the surface in search of food. And what food source sustains these goliaths? Their diet consists almost exclusively of jellyfish, a meal they crisscross the oceans to find. Leatherbacks have been declining in recent decades, and some predict they will be gone by the end of this century. Why? Because of two primary factors: human redevelopment of nesting beaches and commercial fishing. There are only twenty-nine index beaches in the world where these turtles nest, and there is immense pressure to develop most of them into homes or resorts. At the same time, longline and gill net fisheries continue to overwhelm waters frequented by leatherbacks. In The Leatherback Turtle, James R. Spotila and Pilar Santidrián Tomillo bring together the world’s leading experts to produce a volume that reveals the biology of the leatherback while putting a spotlight on the conservation problems and solutions related to the species. The book leaves us with options: embark on the conservation strategy laid out within its pages and save one of nature’s most splendid creations, or watch yet another magnificent species disappear.

Download or read book 2000 IUCN Red List of Threatened Species written by Craig Hilton-Taylor and published by IUCN. This book was released on 2000 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Release of the 2000 Red List is a major landmark for IUCN. It is the first time that listings of animals and plants have been combined and the first time that the Red List has been produced on CD-ROM. The 2000 Red List combines new assessmentsincluding all bird species, many antelope and bat species, most primates and sharks, all Asian freshwater turtles, more molluscs, and many otherswith those from previous publications. The combination of animals and plants into a single list containing assessments of more than 18,000 taxa (11,000 of which are threatened species) and the move towards improved documentation of each species on the list means that a hard-copy version of the Red List would run to several volumes. This, combined with the fact that the Red List will be updated annually, led to the decision to release the Red List in electronic format, via the World Wide Web and as a CD-ROM.

Download or read book The Biology of Sea Turtles Volume II written by Peter L. Lutz and published by CRC Press. This book was released on 2002-12-17 with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt: The success of the first volume of The Biology of Sea Turtles revealed a need for broad but comprehensive reviews of major recent advances in sea turtle biology. Biology of Sea Turtles, Volume II emphasizes practical aspects of biology that relate to sea turtle management and to changes in marine and coastal ecosystems. These topics i

Download or read book The Biology of Sea Turtles Volume III written by Jeanette Wyneken and published by CRC Press. This book was released on 2013-03-25 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the first volume of The Biology of Sea Turtles was published in 1997, the field has grown and matured in ways few of the authors would have predicted-particularly in the areas of physiology, behavior, genetics, and health. Volume III presents timely coverage of emerging areas as well as the integration of approaches and information that did n

Download or read book World Atlas of Seagrasses written by Frederick T. Short and published by Univ of California Press. This book was released on 2003 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Seagrasses are a vital and widespread but often overlooked coastal marine habitat. This volume provides a global survey of their distribution and conservation status.

Download or read book Diel Foraging Patterns in the Juvenile Green Turtle Chelonia Mydas L in St Croix United States Virgin Islands written by John C. Ogden and published by . This book was released on 1983 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The diel foraging behavior of juvenile green turtles (Chelonia Mydas L.) ~ 7 to 8 kg in size was studies by visual observations from a fixed point and by acoustical tracking of three tagged animals, two of which were followed for >1 wk. Green turtles fed in a shallow seagrass-covered bay most commonly by day. There were usually two feeding bouts, one in the morning and one in the afternoon and each turtle visited a characteristic feeding area. Turtles were inactive at night and usually in mid-day in characteristic resting sites in coral reefs separated from the feeding sites by 0.2 to o.5 km. Pre-sunrise feeding activity was noted consistently in one tagged turtle while the other entered the feeding area later in the morning and remained there much of the day. Approximately 9 h per day were spent on the feeding sites by both turtles where the major food of one was determined by fecal examination to be turtle grass Thalassia testudinum König. Turtles were occasionally observed in groups of up to three, but they appeared to be generally solitary rather that social in their behavior.