Download or read book Foraging Ecology of Green Turtles Chelonia Mydas on the Texas Coast as Determined by Stable Isotope Analysis written by Catherine Concetta Theresa Gorga and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The green turtle, Chelonia mydas, is a circumglobal species that exhibits several important developmental or ontogenetic shifts throughout its life history. The first major shift occurs when juvenile turtles migrate from pelagic habitat, where they forage as omnivores, to coastal neritic habitat, where they become primarily herbivores, foraging on algae and seagrass. Anecdotal evidence and gut-content analyses suggest that juvenile green turtles in south Texas bays, such as the lower Laguna Madre and Aransas Bay, undergo an additional ontogenetic shift during this important life history stage. Evidence from stable isotope analysis (SIA) of scute tissues of green turtles from Texas' lower Laguna Madre and Aransas Bay supports an intermediate stage between this species' shift from pelagic waters to seagrass beds in neritic waters; this additional shift comprises an initial recruitment of post-pelagic juveniles to jetty habitat located on the channel passes Gulf-ward of adjacent bays before subsequently recruiting to seagrass beds in these bays. Examination of stable carbon ([delta]13C) and nitrogen ([delta]15N) isotopes in microlayers of scute tissue from several size classes of green turtles from the lower Laguna Madre and Aransas Bay was used to confirm the occurrence of two ontogenetic shifts. Smaller green turtles (35 cm SCL) exhibited more depleted [delta]13C signatures and more enriched [delta]15N signatures, consistent with jetty habitat, compared to those of larger counterparts ( 45 cm SCL) that displayed enriched [delta]13C signatures and depleted 15N signatures, consistent with seagrass habitat. Changes in the isotopic composition between these size classes indicate distinct shifts in diet. Post-pelagic juveniles first recruit to jetty habitat and forage primarily on algae, before subsequently shifting to seagrass beds and foraging primarily on seagrass. These findings indicate the use of a characteristic sequence of distinct habitats by multiple life history stages of green turtles in Texas bays, a conclusion with broad management implications for this endangered species.
Download or read book Advances in Understanding Sea Turtle Use of the Gulf of Mexico written by Donna Jill Shaver and published by Frontiers Media SA. This book was released on 2022-03-18 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Laguna Madre of Texas and Tamaulipas Revised Edition written by Kim Withers and published by Texas A&M University Press. This book was released on 2024-06-03 with total page 713 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Laguna Madre is the only hypersaline coastal lagoon on the North American continent and only one of five worldwide. The lagoon is renowned for its vast seagrass meadows, huge wintering redhead population, and bountiful fishing grounds. In 2000, the Nature Conservancy, whose mission is the conservation of biodiversity through protection of habitat, recognized the need to amass all known information about the Laguna Madre and implement a science-based conservation agenda. From those efforts came the first edition of this book. Now completely revised and updated, this second edition of The Laguna Madre of Texas and Tamaulipas is the culmination of two decades of additional research and continued conservation efforts in the region. Nearly 100 years of literature on the Laguna Madre and surrounding environments has been synthesized here. With 150 figures and illustrations, the book takes a broad and comprehensive look at both the Texan and Tamaulipan Laguna Madre. The value of this book for scientists, conservationists, resource managers, and policy makers involved in the future of the Texas and Mexico coasts is clear. Coastal residents, birders, anglers, and nature lovers who want to learn about and take care of the Laguna Madre will find this to be an indispensable guide.
Download or read book Habitats and Biota of the Gulf of Mexico Before the Deepwater Horizon Oil Spill written by C. Herb Ward and published by Springer. This book was released on 2017-06-26 with total page 948 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is open access under a CC BY-NC 2.5 license. The Gulf of Mexico is an open and dynamic marine ecosystem rich in natural resources but heavily impacted by human activities, including agricultural, industrial, commercial and coastal development. The Gulf of Mexico has been continuously exposed to petroleum hydrocarbons for millions of years from natural oil and gas seeps on the sea floor, and more recently from oil drilling and production activities located in the water near and far from shore. Major accidental oil spills in the Gulf are infrequent; two of the most significant include the Ixtoc I blowout in the Bay of Campeche in 1979 and the Deepwater Horizon Oil Spill in 2010. Unfortunately, baseline assessments of the status of habitats and biota in the Gulf of Mexico before these spills either were not available, or the data had not been systematically compiled in a way that would help scientists assess the potential short-term and long-term effects of such events. This 2-volume series compiles and summarizes thousands of data sets showing the status of habitats and biota in the Gulf of Mexico before the Deepwater Horizon Oil Spill. Volume 2 covers historical data on commercial and recreational fisheries, with an analysis of marketing trends and drivers; ecology, populations and risks to birds, sea turtles and marine mammals in the Gulf; and diseases and mortalities of fish and other animals that inhabit the Gulf of Mexico.
Download or read book Diet Characterization in Immature Neritic Green Turtles Chelonia Mydas Using Gut Contents and Stable Isotope Analyses written by Natalie Christine Williams and published by . This book was released on 2012 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent developments in open water research have refined our understanding of green turtle, Chelonia mydas, foraging ecology, but diet characterization among populations remains understudied. Previous hypotheses state that once young green turtles recruit to shallow water habitat they shift rapidly from an omnivorous to herbivorous diet. Supporting evidence has primarily been derived from traditional gut content analysis that only provides a small window in time to perceive the diet of an animal. In contrast, stable isotope analysis explore show a consumer uses its resources over a broad temporal scale. We tested the dietary shift hypothesis using gut content and stable isotope analyses to assess the nutritional ecology of a juvenile green turtle aggregation in the northern Gulf of Mexico. We examined the gut contents of 65 green turtles collected from 2008 and 2011 hypothermic stunning events in St. Joseph Bay, Florida. Gut contents were evaluated using volume, dry mass, percent frequency of occurrence, and index of relative importance (IRI). Juvenile green turtles showed omnivorous feeding behavior, feeding on a variety of animal and vegetal items with a bias towards seagrass and tunicates. In addition, we evaluated feeding consistency by stable isotope patterns from epidermis tissue. We measured the stable carbon (delta13C)and nitrogen (delta15N)isotope values in epidermis of 43 green turtles, ranging from 22.5 to 72.7cm in curved carapace length (CCLmin), and eight known prey items (e.g., algae, seagrasses, invertebrates) collected in 2011. Our study provides a foundation for characterizing the foraging ecology of green turtles in St. Joseph Bay and highlights the value of utilizing isotopic ecology for further foraging studies.
Download or read book Proceedings of the Thirty first Annual Symposium on Sea Turtle Biology and Conservation written by and published by . This book was released on 2012 with total page 352 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 Long term Changes in Juvenile Green Turtle Abundance and Foraging Ecology in the Indian River Lagoon Florida written by Christopher Augustus Long and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine turtles are distributed in temperate, sub-tropical and tropical waters and beaches worldwide, often in areas heavily impacted by humans. Although there are many threats to marine turtle populations, the growing threats of nutrient pollution and harmful algal blooms are relatively understudied despite their widespread impacts on coastal marine ecosystems that marine turtles depend on. By studying juvenile green turtles (Chelonia mydas) in the Indian River Lagoon, Florida, where nutrient pollution and HABs are a widespread and longstanding issue, I aimed to conduct a case study of how these threats may affect this federally Threatened species. In Chapter 2, I used four concurrent, 18-year data sets to characterize and assess the interrelatedness of long-term trends in seagrass cover, macroalgae occurrence, juvenile green turtle abundance, and juvenile green turtle growth rates. From 2000 to 2018, IRL seagrass cover declined precipitously, macroalgae rose slowly through 2011 then declined during two severe HABs, juvenile green turtle abundance declined slowly, and growth rates declined through 2011 then rose through 2018. In Chapter 3, I conducted a 9-year study of juvenile green turtle foraging ecology using a comparative stable isotope approach. I found that carbon and nitrogen stable isotopic variance declined during and after two severe HABs in the IRL. In Chapter 4, I used two complementary methods to assess the diet of juvenile green turtles after two severe algal blooms in order to assess changes compared to previous diet studies. Visual identification of forage items showed that juvenile green turtle diet remained dominated by nutrient-tolerant red macroalgae with smaller components of seagrass and green algae; metabarcoding techniques largely failed to resolve their diet. My results highlight the web of complex effects and responses that factor in to determining the effects of nutrient pollution and HABs on juvenile green turtles. Future studies of habitat selection, foraging ecology, and the effects of these on juvenile green turtle growth and survival are needed to fully assess the threat of nutrient pollution.
Download or read book New frontiers in the application of stable isotopes to ecological and ecophysiological research written by Keith Alan Hobson and published by Frontiers Media SA. This book was released on 2023-08-14 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Foraging Ecology of the Green Sea Turtle Chelonia Mydas written by Kate'Lyn Wills and published by . This book was released on 2010 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Green Turtle and Man written by James Jerome Parsons and published by . This book was released on 1962 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ecology of Juvenile Green Turtles Chelonia Mydas at a Temperate Foraging Area in the Northeastern Gulf of Mexico written by Erin McMichael and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: In recent years, scientists have recognized the need to conduct in-water studies to better understand the biology of juvenile sea turtles. Little is known regarding the seasonal abundance of juvenile populations in temperate developmental areas such as those in the Gulf of Mexico. It is likely that the Gulf of Mexico supports a year-round population of juvenile sea turtles.
Download or read book Tracking Turtles Back in Time written by Calandra N. Turner Tomaszewicz and published by . This book was released on 2016 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: Of the five species of sea turtles that inhabit the east Pacific Ocean, two, the North Pacific loggerhead (Caretta caretta) and East Pacific green turtle (Chelonia mydas), experience some of the highest rates of globally documented mortality in a productive foraging hotspot near the Baja California Peninsula (BCP), Mexico. This area, the Gulf of Ulloa, overlaps with high levels of fishing, resulting in thousands of dead turtles, many that wash up on the beach of Playa San Lázaro on the BCP. It is unknown how long loggerheads inhabit distinct regions of the North Pacific, and to what degree juvenile individuals in the population demonstrate variation in their life history patterns. Similarly, it is unknown how long green turtles occupy oceanic regions of the eastern Pacific before settling into more nearshore habitats, or how they use the Gulf of Ulloa. My research determined the residency duration at different foraging grounds within the eastern Pacific, as well as basic demographic information such as age-at-settlement, age-at-maturation, and timing of ontogenetic shifts, for these two endangered sea turtle populations. By determining life history parameters and the length of time individuals in these populations spend in distinct high-risk habitats, managers can better understand exposure to spatially explicit threats and prioritize conservation approaches. I focused particularly on duration of time spent in the high-bycatch waters of the Gulf of Ulloa. To this end, I developed a novel technique that combined skeletochronology (the study of growth and age increments in bones) with sequential stable carbon ([delta]13C) and nitrogen ([delta]15N) isotope analysis of humerus bone growth layers. Naturally occurring stable isotope gradients exist in ocean systems such that habitats and foraging behaviors can be distinguished (i.e. nearshore vs. offshore habitats or high vs. low trophic levels). Given these isotope gradients, the combination of skeletochronology with stable isotope analysis of sequentially sampled growth layers provides a multi-year record of location, diet, size, age, and annual growth of individual turtles, allowing the reconstruction of life history and long-term habitat use patterns. The combination of these techniques allowed me to address questions that could not be answered using either technique alone.
Download or read book Synopsis of the Biological Data on the Green Turtle Chelonia Mydas Linnaeus 1758 written by Harold F. Hirth and published by . This book was released on 1997 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Using Biomarkers to Assess the Migratory Ecology and Reproduction of the Florida Green Turtle Chelonia Mydas written by Ryan Maddox Chabot and published by . This book was released on 2017 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Migratory connectivity between breeding and foraging areas is a vital component of the ecology of a diverse collection of marine vertebrates. Habitat quality, composition, and resource availability at these locations have direct ramifications for individual fitness. The green turtle (Chelonia mydas) is a long-lived, highly migratory species of conservation concern. Important green turtle nesting habitat in Florida is protected, but more information is needed to identify foraging habitats and the influence these habitats have on reproduction. Here, I used stable isotope analysis of [delta]13C, [delta]15N, and [delta]34S and satellite telemetry validation to determine the number of putative foraging areas used by the breeding aggregation at the Archie Carr National Wildlife Refuge (ACNWR), and the relative contribution of each foraging area. I evaluated the influence of foraging area and other variables on egg size, clutch size, hatching success, and emerging success using model selection frameworks. Isotopic values of skin and eggs were used to build conversion equations between the two tissue types. Results suggest strong migratory connectivity between the ACNWR and the Florida Keys/Florida Bay complex. I found that the influences of foraging area are likely to be more detectable when evaluating female-centric fitness metrics like clutch size and egg size; these influences are more muted in hatching and emerging success, which are strongly influenced by nest incubation conditions. These are the first green turtle-specific tissue conversion equations for [delta]13C and [delta]15N, and the first [delta]34S equation for any marine turtle species. These will allow researchers to have a “common currency” between frequently collected samples to better compare results.
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 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.
