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1
Cason, Heather L. "Nesting behavior, growth rates, and size distribution of loggerhead sea turtles (Caretta caretta) on Blackbeard Island National Wildlife Refuge an evaluation of recruitment in Georgia /." Click here to access thesis, 2009. http://www.georgiasouthern.edu/etd/archive/spring2009/heather_l_cason/cason_heather_l_200901_ms.pdf.
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Thesis (M.S.)--Georgia Southern University, 2009."A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Directed by David C. Rostal. ETD. Includes bibliographical references (p. 47-49)
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Le, Gouvello Du Timat Diane Zelica Marie. "The effects of turtle-introduced nutrients on beach ecosystems." Thesis, Nelson Mandela Metropolitan University, 2016. http://hdl.handle.net/10948/6959.
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Resource subsidies are flows of nutrients from one ecosystem to another. Sandy beach ecosystems are at the interface between land and sea and thus receive nutrients from both land/seascapes. The seasonal nesting of sea turtles introduces large inputs of eggs, and so nutrients, onto sandy beach ecosystems, but little is known about the effects of these spatially and temporally variable nutrient input pulses on the dynamics of consumers in the recipient system. In this study, I examined the ecological role of sea turtles as vectors of nutrients that introduce large amounts of nutrients (in the form of eggs) from distant foraging grounds into nutrient-poor beach ecosystems. Although some of the nutrients return to the sea in the form of hatchlings, nutrients from unhatched and depredated eggs, dead and predated hatchlings, as well as chorioallantoic fluid and egg shells remain on the beach and presumably enter sandy beach food webs. I hypothesized that turtle nutrients significantly increase the availability of nutrients to sandy beach ecosystems and that those nutrients are incorporated by both terrestrial and marine food webs. These hypotheses were tested by comparing isotopic signatures of 13C and 15N of consumers on beaches with high and low turtle nest densities. The response of meiofauna to the decomposition of turtle eggs was also investigated. I predicted that meiofaunal abundance is positively affected by turtle nutrients and that higher meiofaunal abundances will be obtained in decomposing, depredated nests. I tested this hypothesis by comparing meiofaunal abundance in naturally predated nests to densities away from turtle nests (as a control). An in situ experiment that mimics conditions of naturally predated sea turtle nest, was set up to test meiofaunal community responses to turtle nutrients over time. The study indicates that sea turtle eggs represent a short pulsed resource subsidy that increases the nutrient and energy budget of sandy beach ecosystems. The results show that of the five potential nutrient pathways tested, ghost crabs appear to consume egg nutrients in measurable quantities, altering their diet and feeding behaviour according to food availability. The study also showed that there was a strong, but short-lived positive response of meiofauna to the introduction of nutrients, with increased abundance of all taxa in predated nests and experimental treatments. This response was particularly strong for nematodes which peaked in abundance after seven days. I conclude that turtle-derived nutrients represent a pulsed resource subsidy that makes significant contribution to the energy budget of sandy beach/dune ecosystems.
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Goshe, Lisa R. "Age at maturation and growth rates of green sea turtles (Chelonia Mydas) along the southeastern U.S. Atlantic Coast estimated using skeletochronology." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/goshel/lisagoshe.pdf.
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Avens, Larisa I. "Homing behavior, navigation, and orientation of juvenile sea turtles." Online version in pdf format, 2003. http://www.sefsc.noaa.gov/PDFdocs/Avens%5FDissertation%5F2003.pdf.
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Pendoley, Kellie Lee. "Sea turtles and the environmental management of industrial activities in North West Western Australia." Thesis, Pendoley, Kellie Lee (2005) Sea turtles and the environmental management of industrial activities in North West Western Australia. PhD thesis, Murdoch University, 2005. https://researchrepository.murdoch.edu.au/id/eprint/254/.
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The nesting demographics of sea turtles using beaches within the Barrow, Lowendal, Montebello (B-L-M) island complex on the North West Shelf of Western Australia were examined in the context of their spatial and temporal distribution and potential for exposure to industrially based artificial light sources. The distribution of overnight turtle tracks throughout the island complex confirmed high density nesting of Chelonia mydas (green turtles) on deep, sandy and high energy beaches and Natator depressus (flatback turtles) on deep, sandy and low energy beaches, while Eretmochelys imbricata (hawksbill turtle) tracks were most visible on shallow, sandy beaches adjacent to near shore coral reef habitat. The three species exhibited a summer nesting peak. Hawksbill turtles commenced nesting in September and continued through to January, green turtles commenced in November and decreased in March. Flatback turtles displayed the most constrained nesting season reported to date in Australia with 86% of the animals visits recorded in December and January only. Nesting population sizes estimated for the three species suggest that on a national scale the B-L-M complex is a moderately large green turtle and a large flatback rookery site. The hawksbill rookery is large on an international scale. While none of the green turtle nesting beaches fell within a 1.5 km radius of industrially based artificial light sources an estimated 42% of nesting flatback turtles and 12% of nesting hawksbill turtles were potentially exposed to these light sources.
Testing of green turtle and hawksbill hatchling response to different wavelengths of light indicate that hatchlings from the B-L-M region respond to low wavelength much like hatchlings tested in North America (Witherington 1992a). Flatback hatchlings displayed a similar preference for low wavelength light however their responses to discrete light wavelengths between 400 nm and 700 nm suggest that this species may not discriminate well between wavelengths that lie between 450 nm and 550 nm. This response may be related to the rapid attenuation of visible light that occurs in the turbid near shore habitats favoured by this species.
Field based arena studies carried out to investigate hatchling behaviour on nesting beaches with light types commonly used in industrial settings found green turtle and flatback hatchlings are significantly attracted to these lights compared to controls. Lights that emit strongly in the low wavelength range (i.e. metal halide and fluorescent) caused hatchling misorientation at lower intensities than the test light that emitted relatively poorly in this range (high pressure sodium vapour). Hawksbill hatchlings tested in situ under the influence of actual oil and gas onshore and offshore facility based lighting were disrupted from the most direct line to the ocean by these light emissions. Emergence fan mapping methods that measure hatchling orientation on nesting beaches were refined and are proposed as an alternative monitoring tool for use on beaches that are logistically difficult to access for large scale experimental orientation studies. The hatchling behaviour was clearly complicated by beach topography and moon phase.
Satellite tracking of post nesting female green and hawksbill turtles from North West Shelf rookeries has identified the Western Australian location of migratory corridors and foraging grounds for these species while Scott Reef turtles migrate from their south Timor Sea rookery to Northern Territory waters. Green turtle nesting on Barrow Island and Sandy Island (Scott Reef) forage at feeding grounds 200 - 1000 km from their nesting beaches. Hawksbill turtles nesting at Varanus Island and Rosemary Islands forage at locations 50 - 450 km from their nesting beaches. While all of the nesting beaches within the B-L-M island complex are protected under the Barrow-Montebello Marine Conservation Reserves, the only foraging ground similarly protected is the Northern Territory foraging ground used by Scott Reef green turtles. None of the foraging grounds used by North West Shelf green or hawksbill turtles is currently protected by conservation reserves.
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Pendoley, Kellie Lee. "Sea turtles and the environmental management of industrial activities in North West Western Australia." Pendoley, Kellie Lee (2005) Sea turtles and the environmental management of industrial activities in North West Western Australia. PhD thesis, Murdoch University, 2005. http://researchrepository.murdoch.edu.au/254/.
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The nesting demographics of sea turtles using beaches within the Barrow, Lowendal, Montebello (B-L-M) island complex on the North West Shelf of Western Australia were examined in the context of their spatial and temporal distribution and potential for exposure to industrially based artificial light sources. The distribution of overnight turtle tracks throughout the island complex confirmed high density nesting of Chelonia mydas (green turtles) on deep, sandy and high energy beaches and Natator depressus (flatback turtles) on deep, sandy and low energy beaches, while Eretmochelys imbricata (hawksbill turtle) tracks were most visible on shallow, sandy beaches adjacent to near shore coral reef habitat. The three species exhibited a summer nesting peak. Hawksbill turtles commenced nesting in September and continued through to January, green turtles commenced in November and decreased in March. Flatback turtles displayed the most constrained nesting season reported to date in Australia with 86% of the animals visits recorded in December and January only. Nesting population sizes estimated for the three species suggest that on a national scale the B-L-M complex is a moderately large green turtle and a large flatback rookery site. The hawksbill rookery is large on an international scale. While none of the green turtle nesting beaches fell within a 1.5 km radius of industrially based artificial light sources an estimated 42% of nesting flatback turtles and 12% of nesting hawksbill turtles were potentially exposed to these light sources.
Testing of green turtle and hawksbill hatchling response to different wavelengths of light indicate that hatchlings from the B-L-M region respond to low wavelength much like hatchlings tested in North America (Witherington 1992a). Flatback hatchlings displayed a similar preference for low wavelength light however their responses to discrete light wavelengths between 400 nm and 700 nm suggest that this species may not discriminate well between wavelengths that lie between 450 nm and 550 nm. This response may be related to the rapid attenuation of visible light that occurs in the turbid near shore habitats favoured by this species.
Field based arena studies carried out to investigate hatchling behaviour on nesting beaches with light types commonly used in industrial settings found green turtle and flatback hatchlings are significantly attracted to these lights compared to controls. Lights that emit strongly in the low wavelength range (i.e. metal halide and fluorescent) caused hatchling misorientation at lower intensities than the test light that emitted relatively poorly in this range (high pressure sodium vapour). Hawksbill hatchlings tested in situ under the influence of actual oil and gas onshore and offshore facility based lighting were disrupted from the most direct line to the ocean by these light emissions. Emergence fan mapping methods that measure hatchling orientation on nesting beaches were refined and are proposed as an alternative monitoring tool for use on beaches that are logistically difficult to access for large scale experimental orientation studies. The hatchling behaviour was clearly complicated by beach topography and moon phase.
Satellite tracking of post nesting female green and hawksbill turtles from North West Shelf rookeries has identified the Western Australian location of migratory corridors and foraging grounds for these species while Scott Reef turtles migrate from their south Timor Sea rookery to Northern Territory waters. Green turtle nesting on Barrow Island and Sandy Island (Scott Reef) forage at feeding grounds 200 - 1000 km from their nesting beaches. Hawksbill turtles nesting at Varanus Island and Rosemary Islands forage at locations 50 - 450 km from their nesting beaches. While all of the nesting beaches within the B-L-M island complex are protected under the Barrow-Montebello Marine Conservation Reserves, the only foraging ground similarly protected is the Northern Territory foraging ground used by Scott Reef green turtles. None of the foraging grounds used by North West Shelf green or hawksbill turtles is currently protected by conservation reserves.
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Groshens, Erica B. "Internesting and post-nesting movement and behavior of Hawksbill sea turtles, Eretmochelys imbricata, at Buck Island Reef National Monument, St. Croix, USVI." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09292009-020339/.
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Snoddy, Jessica E. "Physiological status and post-release mortality of sea turtles released from gillnets in the Lower Cape Fear River, North Carolina." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/snoddyj/jessicasnoddy.pdf.
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Coles, William C. "Aspects of the biology of sea turtles in the Mid-Atlantic Bight /." W&M ScholarWorks, 1999. http://web.vims.edu/library/Theses/Coles99.pdf.
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Honarvar, Shaya Spotila James R. "Nesting ecology of Olive Ridley (Lepidochelys olivacea) turtles on Arribada nesting beaches /." Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2824.
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Rybitski, Mary J. "Distribution of Organochlorine Pollutants in Sea Turtles." W&M ScholarWorks, 1993. https://scholarworks.wm.edu/etd/1539617662.
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Cheung, Sze-man. "Ecology, conservation and trade of freshwater turtles in Hong Kong and Southern China, with particular reference to the critically endangered Cuora trifasciata /." View the Table of Contents & Abstract, 2007. http://sunzi.lib.hku.hk/hkuto/B38724790.
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Brazier, Wayne. "Environmental cues and sensory preferences directing the nesting process in loggerhead turtles, caretta caretta, nesting in Maputaland, South Africa." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1015688.
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Animals use their senses for everything on an immediate, and day to day fashion – detecting danger, finding food, finding mates among other activities. In sea turtles and other migratory species senses are used for long-distance migrations. Senses such as smell, vision and hearing, have been studied experimentally under laboratory conditions but seldom have been investigated in the field. This thesis takes a combination of field and laboratory experiments and investigates some of the hypotheses involved in natal homing and nest site selection. The loggerhead’s nesting distribution in Maputaland is distinct with characteristic high and low density nesting areas which are consistent from year to year. Investigations by earlier researchers on these beaches suggested that beach characteristics, such as beach morphodynamic type and beach width, do not appear to influence the beaches at which loggerheads emerge to nest. The high density nesting area (with approximately 440 loggerhead emergences/km) have similar beach characteristics as the low density nesting area (with <50 loggerhead emergences/km). It is therefore suggested that there is another cue that drives nest site selection. It can either be related to a physical characteristic not yet realised, or is a non-physical (but chemical or biological) cue. This dissertation aims to identify the sensory inputs received during the nest selection process, as well as sea-finding ability after nesting. To investigate the mechanism causing the high-density as opposed to the low-density nesting area, three potential drivers were investigated namely: chemical imprinting (as a natal beach cue), ambient and artificial light (as deterrents) and social facilitation (as a learned behaviour). It was also attempted to identify the strength of the most common senses – vision, hearing and smell. As animal ethics restricts interfering with emerging or nesting turtles, the strengths of these senses were tested during sea-finding by adult loggerheads. The results indicate that sulfide concentrations appear to be used as chemical cues for nesting as these concentrations are elevated (>150 percent) in the high density nesting beaches compared to the low density nesting beaches within and among seasons however further investigations are required. Artificial light (range: 0.045–0.5 lux) is an active deterrent of female emergences while ambient light, even under extreme conditions such as lightning during electric storms (up to 8.2 lux), appears to have no observable influence on the spatial or temporal distributions of emergences. Social facilitation appears unlikely as a primary nest site selection factor for loggerheads. It may however, play a minor secondary role to preferred areas or hotspots. Sea-finding in post-nesting female loggerheads appears to be driven exclusively by visual cues such as the light horizon, with minimal to no influence from other cues (the sound of the breakers, slope or smell of the ocean) which solidify the visual system’s use in sea-finding. This research on the nest site selection of loggerheads and the sensory systems involved in this process has added valuable information to the limited pool of knowledge already present and has created a solid framework on which further investigations can be based. Future work in this field should focus on integrating a suite of sensory stimuli and cues to receive a greater understanding of the sensory systems used in nest site selection.
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Alfaro, Shigueto Joanna Olga Gissella. "Ecology and conservation of sea turtles in Peru." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3472.
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Some of the key elements to assess the status of any wildlife population in a given geographical area are the levels of recruitment, survival and mortality. Whilst most of the information on marine turtles has been obtained from nesting sites, turtles spend most of their lives at sea. The conservation status of marine turtles in the southeast Pacific is poorly documented. This is particularly true for countries like Peru, where nesting events are very rare, although five species of turtles from populations from all over the Pacific basin, use these waters as foraging grounds. Little information exists on the threats to turtle populations in foraging areas or the magnitude of these impacts. Small-scale fisheries are a globally important economic activity serving as a source of food and employment for ca. 1 billion people; however we show that they also have serious impacts on marine turtle populations from all over the Pacific basin in the form of incidentally captured marine turtles. The five chapters that constitute this thesis are intended to increase our understanding of small-scale fisheries impacts on this taxon during their aquatic life stages. This work focuses on describing these fisheries, their impacts on marine turtles and proposes methodologies to monitor and assess the level of bycatch from small-scale fisheries. We also discuss alternative ways to prevent fisheries interactions and promote the involvement of artisanal fishermen in the southeast Pacific in implementing conservation solutions.
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Houghton, J. D. R. "The behaviour and physiological ecology of sea turtles." Thesis, Swansea University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637311.
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Male loggerhead turtles (Caretta caretta) were observed in a shallow (< 2 m) lagoon. Preferred food sources were Mytilus galloprovincialis, Posidonia oceanica and discarded fish entrails. Foraging dives were of short duration, presumably because of the small lung volumes required to attain neutral buoyancy at shallow depths. In-water observations of juvenile hawksbill turtles (Eretmocheyls imbricata) were made. Curved carapace length was estimated to within 10 cm of actual size. Foraging grounds of adults and juveniles did not appear to overlap. Juvenile hawksbills alternated between short, shallow foraging dives and deeper, longer resting dives. Time depth recorders were attached to loggerhead turtles (n = 2). Dives to the seabed (< 20 m) accounted for 59% and 755 of the interesting interval. Benthic dives decreased markedly following or prior to a nesting event. This contrasted the predominance of open-water dives reported in Japan. Open-water resting may occur when turtles are travelling and, conservely, when little time is spent travelling turtles opt to remain predominantly on the seabed. Atypically deep v-dives were identified for loggerhead and green (chelonia mydas) turtles. These appeared pre-determined, within the physiological scope of the species and may allow direct bathymetric information to be gathered. Patterns of hatchling emergence were documented and related to in-nest thermal conditions. Variation existed between and within individual nests. Hatchlings from nests displaying large thermal range emerged over a longer time-scale than those with more uniform temperatures. Incubation during data were used as a proxy of sex ratios. Variation existed within and between nesting seasons with 'atypical' seasons characterised by predominantly male production. Egg failure and neonate mortality were investigated in loggerhead clutches. First clutches were more likely to contain a higher proportion of eggs displaying no gross signs of development. Possible factors underpinning this are explored as are its implications at population level.
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Hochscheid, Sandra. "Thermoregulation, metabolism and buoyancy regulation in sea turtles." Thesis, University of Aberdeen, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288349.
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1. This study was performed to investigate a mechanism of heat exchange in sea turtles and how temperature and different acclimation time affects their metabolic rates. In another part of this thesis I aimed to test the possibility of a correlation between dive duration and both metabolic rate and state of buoyancy known to be regulated via the gas volume in the lungs of Chelonian sea turtles. 2. All experiments were conducted on captive loggerhead (Caretta caretta) and green turtles (Chelonia mydas) housed in a individual tanks with circulating seawater from the adjacent Gulf of Naples (Western Mediterranean). The total range of body masses of turtles used encompassed 2 to 60 kg. 3. It was demonstrated, using Doppler ultrasound, that sea turtles change blood flow in their appendages in response to external cooling and heating. Although this was efficient to accelerate whole body warming and delay the cooling of the body, turtles eventually equilibrated their body temperatures with that of the surrounding water. 4. The Q10 effect on metabolic rate of sea turtles subject to acute exposure to varying temperatures was 1.3. However, during long term exposure to seasonally decreasing water temperatures turtles showed a more pronounced reducted of metabolic rate (O10 = 5.4). Contemporaneously food intake and general activity were greatly reduced as well and dive durations increased. Body temperatures showed the same seasonal trend as the decreasing water temperatures. 5. Oxygen consumption rates of individual turtles, measured over 24-h-periods, peaked at different times of the day and no specific dynamic action after feeding could be detected.
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Hamed, Ahmed. "Economic Valuation of Florida Sea Turtles in Face of Sea Level Rise." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5942.
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Sea level rise (SLR) is posing a great risk of flooding and inundation to coastal areas in Florida. Some coastal nesting species, including sea turtle species, have experienced diminished habitat from SLR. In an effort to assess the economic and ecosystem service loss to coastal areas with respect to sea turtles Contingent Valuation Method (CVM) and Habitat Equivalency Analysis (HEA) were used.
The CVM was used to measure the economic impacts of SLR on sea turtles. Open-ended and dichotomous choice CVM was used to obtain the willingness to pay (WTP) values of Florida residents to implement certain mitigation strategies which would protect Florida's east coast sea turtle nesting areas. The problem of sample selection bias was reduced by surveying residents of two cities that would potentially have varying interest in coastal conservation due to their relative distance from the coast. The hypothetical WTP of Florida households to implement policies designed to protect sea turtle habitat from development encroachment was estimated to be between $21 and $29 per year for a maximum of five years. Characteristics of respondents were found to have statistically significant impacts on their WTP. Findings include a negative correlation between the age of a respondent and the probability of an individual willing to pay the hypothetical WTP amount. Counter intuitively, it was found that WTP of an individual was not dependent on prior knowledge of the effects of SLR on sea turtle habitat. As the level of this awareness increased, the probability to pay the hypothetical WTP value decreased. The greatest indicators of whether or not an individual was willing to pay to protect sea turtle habitat were the respondents' perception regarding the importance of sea turtle population health to the ecosystem, and their confidence in the conservation methods used.
Concepts of Habitat Equivalency Analysis were used in order to determine the ecosystem service lost due to SLR. The study area of Archie Carr National Wildlife Refuge (ACNWR) has a continually increasing sea turtle population due to various conservation efforts. However, how the inundation of the coastal area will injure this habitat was assessed, and if mitigation strategies to compensate for the loss are necessary. The carrying capacity (CC) of the refuge was chosen as the metric of the ecosystem service. Using the estimated area of ACNWR and the approximate area needed by a sea turtle to nest, the theoretical number of sea turtle nests possible on the refuge was calculated. This value was then projected to the year 2100 using the sea level rise scenarios provided by IPCC (2007) and NRC (2010). In order to quantify the injury caused by the decrease in the refuge's CC, the number of sea turtle nests on the refuge was projected to the year 2100 using the data obtained over the past 30 years. The analysis concludes a potential loss of service to be experienced as early as 2060's due to the carrying capacity of the refuge diminishing with the loss of the habitat due to the increase in the mean sea level.M.S.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering; Water Resources Engineering
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de, Wet Anje. "Factors affecting survivorship of loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles of South Africa." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1007900.
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Loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles as well as their eggs and hatchlings have been protected on their nesting beach in South Africa (SA) since 1963. Both nesting populations were expected to show similar trends in recovery following the application of identical protection and conservation measures. The loggerhead nesting population has responded favourably to these protection efforts. In contrast, the leatherback nesting population showed an initial increase but is currently stable. The reason for this difference in response is thought to be due to differential offshore mortality of these two species. This prompted an investigation into the different sources of sea turtle mortality in the South Western Indian Ocean (SWIO). Specific aims were to identify and quantify sources of loggerhead and leatherback mortality on nesting beaches as well as in the oceans. Reasonable survivorship at all age classes is important to ensure recruitment of new nesting individuals into sea turtle populations. Mortality of nests, eggs per nest and hatchlings were quantified over two seasons for the loggerheads and leatherbacks nesting in SA. The beach was patrolled on foot to encounter and record females emerging from the ocean and later, hatchlings from their nests. The nests were then monitored during the incubation period and excavated once hatched. The fates of 925 nests were determined during these two nesting seasons (2009/2010 and 2010/2011). The main source of loggerhead and leatherback nest destruction was predation (8.6 percent and 15.7 percent respectively) followed by nest erosion (2.2 percent and 6.3 percent respectively). Overall nest success was high but higher for loggerheads (89 percent) than for leatherbacks (78 percent). The main cause of egg mortality for both species was early developmental arrest, followed by predation by ants and ghost crabs. Hatchlings en route to the sea were almost exclusively predated by ghost crabs (4.2 percent of emerged loggerhead hatchlings and 3.2 percent of emerged leatherback hatchlings). It appears that both species benefit from the coastal conservation efforts. When sea turtles leave the nesting beach, either as hatchlings or adults, conservation and monitoring becomes more difficult and sea turtles are exposed to a multitude of threats, including anthropogenic threats. Age classes tend to be spatially separated due to different habitat and dietary requirements. The type of threat sea turtles are exposed to thus depends on the current age class. Offshore sources of mortality in the SWIO were identified and where possible loggerhead and leatherback mortality was quantified and mapped spatially. Loggerheads were mostly exposed to and had the highest mortality in the artisanal fisheries in the SWIO (> 1000 per annum), inshore trawling (ca. 41 per annum), shark nets (protective gill nets) (21.6 ± 6.7 per annum) and the pelagic longline fishery (5.0 ± 4.4 per annum). In contrast, leatherbacks with a pelagic lifestyle, were mostly exposed to pelagic longline fisheries (7.8 ± 7.8 per annum). A spatial analysis of fishing activities indicated that leatherback home ranges overlapped 41percent with pelagic longline fishing activity in the SA EEZ, whereas the overlap between pelagic longliners and loggerhead home ranges was 29 percent. The quantified sources of mortality provide some explanation for the trend in the loggerhead nesting population but not the trend in the leatherback nesting population. Hatchling survivorship to adulthood was estimated to determine the viability of the two nesting populations as well as to determine whether offshore mortality was responsible for the difference in recovery of the two populations. Loggerhead hatchling survivorship to adulthood was estimated at between 2 and 10 per 1000 hatchlings, the minimum requirement for an increasing population. The adopted sophisticated model shows that leatherbacks have a survival rate of 5 to 10 per 1 000 hatchlings. However, this suggests that the population is increasing, but the leatherback population is stable. Perhaps the age to maturity of SA leatherbacks is greater than 12 years, or fisheries-related mortality affects younger age classes than initially thought. It is therefore recommended that the turtle monitoring area is extended to include other potential nesting grounds. In addition, observer or monitoring programs for commercial as well as artisanal fisheries needs to be extended throughout the SWIO to quantify sea turtle mortality. Ultimately a comprehensive multi-regional approach is required for the conservation of these highly migratory species.
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Fish, Marianne R. "Coastal development and sea-level rise : impacts on sandy beaches and sea turtles." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435124.
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Sandy beach habitat is threatened globally by climate change and extensive human modification of coastal areas. Loss of sandy beaches is of concern for the many species dependent on this habitat: in this thesis I focus on sea turtles, which rely on beaches for nesting. To provide a context for the subsequent chapters, I begin by reviewing the ways in which sandy beaches are altered by humans, and how these alterations have affected sea turtles. Resilience of beaches to environmental change depends on local physical and anthropogenic influences. Analysis of the relative vulnerability of coastlines in the Caribbean region to alteration reveals extensive spatial variability. One of the major sources of beach alteration in the Caribbean is the tourism industry and many beaches used by sea turtles are now also used by tourists. I assess the overlap between turtle and tourist beach-state requirements and suggest that integrated management is facilitated where the requirements of turtles and tourists are complementary. One of the impacts of human alteration of coastal areas is extensive beach erosion. The latter part of the thesis focuses on erosion management options. As tourists benefit from maintenance of beaches, I examine the potential for them to fmancially contribute towards beach management. I highlight the management options that would result in beach states preferred by tourists, whilst also maintaining the ecological integrity of beaches. One such option is the use of setback regulations, which aids long-term beach maintenance by moving buildings away from the beach. Models of beach loss under a range of setback-regulation distances and sea-level rise scenarios predict that implementation of setback regulations at a sufficient distance may mitigate beach loss caused by sea-level rise.
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Coufal, Kendra. "A profile of oestrogrens and a survey of endocrine disrupters in marine turtles of Australia and Malaysia /." St. Lucia, Qld, 1998. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16547.pdf.
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Piper, Jessie Celeste 1950. "Anthropology, sustainability and the case of Mexico's sea turtles." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278137.
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Mexico was formerly an important breeding ground for six marine turtle species. Over the last several decades, overexploitation of turtles for their meat, eggs, and hides, as well as habitat destruction, has led to alarming rates of decline in all species. The problem of sea turtle conservation is a promising area for questions of anthropology and sustainable human systems because decline of these species is related to unsustainable development and subsistence practices that have disenfranchised small coastal fishing cooperatives. Common property resource theory aids the analysis of the context in which overexploitation takes place. Conserving sea turtles will depend on the development of localized institutions for managing natural resources in perpetuity and for negotiating the array of regional, national, and global factors relevant to sea turtle endangerment and preservation. Anthropology can play a vital role in this process of developing sustainable interactions between human subsistence needs and natural resource conservation.
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Scott, Rebecca. "Lagrangian analysis of sea turtle ecology." Thesis, Swansea University, 2013. https://cronfa.swan.ac.uk/Record/cronfa42364.
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Many marine organisms are highly mobile, which presents a variety of research and conservation management challenges. Sea turtles are a particularly paradigmatic group of long distant migrants whose movements as adults have been detailed by satellite tracking technology. However, small hatchlings are not amenable to this approach. This thesis used Lagrangian oceanography approaches to study the cryptic lives of juvenile turtles, since ocean currents drive their dispersion from natal beaches. Through increasingly sophisticated and novel uses of Lagrangian surface drifter buoys, state-of- the-art global ocean models and emerging animal life history datasets, my PhD thesis details significant findings of the key life history attributes of these enigmatic migrants. Initially, 1 modelled the dispersal of hatchlings from their nesting beaches to derive the first robust estimates of hatchling growth rates and by so doing, highlighted the long maturation times of turtle species. Then, I programmed hatchling swimming behaviour into ocean model simulations to reveal how these small drifters could improve their survival chances in strong current flows. More interdisciplinary research also highlighted aberrant routes of dispersal that can arise through storm displacements. Subsequent meta-analysis on the movements of flying, swimming and walking migrants highlighted key biological determinants of sea turtle migrations. Spatio-temporal analysis of sea turtle marine protected area (MPA) use highlighted minor (tractable) legislative revisions that would significantly improve MPA effectiveness. Finally, research culminated in a global synthesis of the movement patterns of adult and hatchling sea turtles which provided global support for a new migration paradigm, that whilst adult turtles travel independently of ocean currents, ocean currents still indirectly drive the ontogeny of adult sea turtle migrations and foraging habitat selections due to their past experiences as drifting hatchlings. This new understanding into the biological and physical determinants of sea turtle migration strategies is thus hoped to have broad conservation utility.
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Seney, Erin E. "Historical Diet Analysis of Loggerhead (Caretta caretta) and Kemp's Ridley (Lepidochelys kempi) Sea Turtles in Virginia." W&M ScholarWorks, 2003. http://www.vims.edu/library/Theses/Seney03.pdf.
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Huang, Yedan. "Return migration a case study of "sea turtles" in Shanghai /." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/HKUTO/record/B39558629.
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黃曄丹 and Yedan Huang. "Return migration: a case study of "sea turtles" in Shanghai." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39558629.
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Byles, Richard Allan. "Behavior and ecology of sea turtles from Chesapeake Bay, Virginia." W&M ScholarWorks, 1988. https://scholarworks.wm.edu/etd/1539616593.
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Immature foraging sea turtles occupy Chesapeake Bay, Virginia annually from May through November. Telemetry was used to monitor the movements and behavior of loggerhead, Caretta caretta, and Kemp's ridley, Lepidochelys kempi, turtles during 1981-1985. Both species utilized the estuary for summer foraging, but exhibited habitat-preference and behavioral differences that amounted to resource partitioning between the species. Loggerheads oriented towards major river outflows and tended to move along channel sides with the tidal flow while ridleys occupied shallower foraging areas and did not range as far with the tide. Strong site tenacity was displayed by both species once foraging areas were established. Differences were apparent in respiratory behavior; ridleys remained on the surface for longer and underwater for shorter periods than loggerheads. Ridleys had a tendency to stay on the surface longer during daylight than night hours, whereas loggerheads surfaced and submerged longer during night than daylight. Estimates of daylight respiration behavior of loggerheads (surface to dive time ratio of 1:17) were used to adjust estimates of population size. Replicated aerial surveys for loggerheads yielded an unadjusted mean population over 1982-1985 of 423. A respiration adjustment factor which accounts for turtles unseen because they are below the surface (17 turtles below the surface for every one seen at the surface) yielded an average annual estimate of 7905. Reported mortality is a small percentage (1.4) of the adjusted population estimate. Mark-recapture, aerial survey and biotelemetric techniques were used in 1980 and 1982-1985 to elucidate migrations of loggerheads and ridleys which are incapable of overwintering in Chesapeake Bay. For both species, the period of residence in the Bay was correlated with water temperature. Migrations to the Bay were linked to vernal warming; the heaviest concentrations of turtles were found south of the 18 C isotherm. Fall migration was linked less strongly with declining water temperature and appeared to be related to the onset of winter storms. Migrating loggerheads remained nearshore in southerly currents in the fall. Contact with most telemetered loggerheads was broken in the vicinity of Cape Hatteras, North Carolina. A satellite-tracked loggerhead spent two months in the vicinity of the Gulf Stream offshore before contact was broken.
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Young, Erina J. "Health and disease status of sea turtles in Western Australia." Thesis, Young, Erina J (2022) Health and disease status of sea turtles in Western Australia. PhD thesis, Murdoch University, 2022. https://researchrepository.murdoch.edu.au/id/eprint/66116/.
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The current state of sea turtle health in the Indian Ocean is largely unknown, especially for the endemic flatback turtle (Natator depressus) which is listed as ‘vulnerable’ in Western Australia (WA) and ‘data deficient’ globally. Anecdotally, the causes of illness, injury, and death in Western Australian turtles are comparable to those in other parts of Australia and the world (e.g., spirorchiidiasis, fibropapillomatosis, and marine debris interaction) but scientific studies to validate these reports are particularly limited in this region. To address these knowledge gaps, causes of both live and dead turtle strandings in WA were investigated through an array of veterinary diagnostic techniques including necropsy, clinical pathology, diagnostic imaging, histopathology, parasitology, microbiology, toxicology, and molecular analyses. Health assessments were conducted on live animals to determine baseline levels of health and disease for specific populations, predominately nesting and foraging flatback turtles.
Through these health and disease investigations, baselines were developed, along with the discovery of new diseases in flatback turtles including a novel haemoparasite, Haemocystidium spp., occurring specifically in the foraging life stage; a potentially emerging zoonotic bacterium, Streptococcus iniae associated with a multi-species mass mortality event involving post-hatchlings; as well as spirorchiidiasis, previously unreported in this species. Other unusual and emerging diseases were also reported in sea turtles in this study, including microsporidial myopathy, salt gland adenitis, gout, and pseudogout.
In this study, natural disease-related causes of mortality occurred more frequently than direct anthropogenic causes, with parasitoses the most frequently occurring natural disease. Spirorchiidiaisis was the most common cause of mortality (32.0%) with a prevalence of 93.2% in turtles susceptible to the disease (i.e., excluding the post-hatchling life stage). The next most common cause of mortality was unknown (17.3%), followed by trauma (13.3%), endoparasitosis (10.7%), infectious disease (6.7%), and pneumonia (6.7%), with the remaining mortality categories each accounting for less than 5% of cases (including systemic inflammation, osmoregulatory disorder, gastrointestinal impaction, gastrointestinal foreign body, fibropapillomatosis, and metabolic disorder).
We developed the first flatback turtle reference intervals (RIs) in Reference Value Advisor (RefVal v2.1) following the American Society of Veterinary Clinical Pathology (ASVCP) guidelines. We found flatback turtle RIs were generally similar to other published sea turtle RIs and reference values (RVs) but detected significant differences in our study for the various boundary conditions including life stage (nesting or foraging), as well for measurement methodology (field or laboratory tests), justifying the establishment of separate RIs/RVs for nesting and foraging flatbacks, and for field and laboratory techniques.
This study was the first sea turtle health and disease investigation in WA and the eastern Indian Ocean to offer broader insights into sea turtle health and disease status on a regional scale. These essential baselines provided a number of crucial functions which include serving as a reference point for future studies to monitor changes in population health and disease levels. Specifically, these baseline data will be useful for future comparative studies of the same population where changes are an indication of a changing environment. The blood RIs can be used for disease diagnosis, monitoring progress and assessing prognosis of clinical flatback turtle cases in rehabilitation. Considering that diseases in the marine environment are predicted to rise with increasing anthropogenic pressures, detection of new and emerging diseases is of significance to the global knowledge of sea turtle diseases; and for understanding and mitigating disease threats to sea turtle populations. Finally, this study provided a framework to integrate health into future conservation management decisions to ensure the long-term survival of sea turtles.
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Nichols, Wallace J. "Biology and conservation of sea turtles in Baja California, Mexico." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280439.
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I studied the in-water anthropogenic impacts on sea turtles, origins of sea turtles on foraging and developmental areas, their migration routes, and described regionally appropriate conservation needs. Sea turtles inhabiting Baja California waters originate on distant beaches in Japan, Hawaii, and southern Mexico. Results from genetic analyses, flipper tagging and satellite telemetry indicate loggerhead turtles (Caretta caretta) feeding along Baja California's coast are born in Japan and make a transpacific developmental migration of more than 20,000 km, encompassing the entire North Pacific Ocean and that East Pacific green turtles (Chelonia mydas) originate on and return to rookeries in Michoacan, and the Islas Revillagigedo, Mexico. Hawksbill turtles (Eretmochelys imbricata), once the target of a lucrative fishery for their shell, are now extremely scarce and only juveniles were encountered. The region's importance to the biology of sea turtles, regionally and Pacific-wide, warrants urgent conservation action. While protected legally, sea turtles are subject to furtive hunting and incidental catch. Coastal development, pollution, and boat collision are secondary threats. Annual consumption of sea turtles in the region is estimated at between 7,800 and 30,000 animals. Sea turtles are eaten regularly in most coastal communities and turtles are considered an irreplaceable traditional food. The decline of sea turtles in these waters has cost us both ecologically and culturally. Sea turtle recovery in Baja California, as all conservation activities, will be a matter of cultural and social evolution. For recovery to occur, strong, community-based incentives and educational programs are needed. In the near term, increased enforcement efforts, monitoring of mortality, and establishment of sea turtle sanctuaries are among the solutions. Without expansion to include community-specific initiatives such efforts may be futile. A long-term, multi-faceted sea turtle "conservation mosaic" program has been launched, consisting of community-based research on life history and population biology, an international education and public outreach campaign, regional sea turtle conservation areas, a monitoring and stranding network, and several policy initiatives that will permanently protect sea turtles and their habitat.
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Keinath, John A. "Movements and behavior of wild and head-started sea turtles." W&M ScholarWorks, 1993. https://scholarworks.wm.edu/etd/1539616710.
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Flipper-tagging, aerial surveys, and satellite telemetry was used to investigate the occurrence, migratory routes, distances traveled, swimming speeds, diving behavior, and the relation of water temperature to movements and timing of migration of wild loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) sea turtles. The behavior and movements of head-started loggerhead turtles was investigated with satellite telemetry and compared to wild turtles. Flipper-tagged loggerhead and Kemp's ridley turtles inhabit Chesapeake Bay during the warm months and many return in subsequent seasons. Aerial surveys showed that loggerhead turtles migrate from south of Cape Hatteras to northern waters during May and June, and return to the south of Cape Hatteras in the autumn, usually during October or November. Satellite telemetry supported aerial survey data, and showed that loggerhead and Kemp's ridley turtles migrate nearshore to the south of Cape Hatteras in the autumn, although one loggerhead became pelagic in the North Atlantic. Kemp's ridleys and some loggerheads migrate as far south as Florida for the winter months, while some loggerheads overwinter in the Gulf Stream off North Carolina. Loggerheads which returned to Chesapeake Bay used similar migratory routes during the northerly and southerly migrations. Loggerhead and Kemp's ridley turtles spent up to 94% of 12 h periods submerged (ridley mean = 81%, loggerhead mean = 88%), and mean dive durations ranged from 13 to 124 min (ridley mean = 66 min, loggerhead mean = 74 min), making 13 to 38 dives over a 12 h period (ridley mean = 25, loggerhead mean = 25). Temperatures measured by satellite transmitters attached to Kemp's ridley turtles ranged from 13-23 C (mean = 17 C), while loggerhead temperatures ranged from 6-33 C (mean = 20 C). Movements of turtles appear to be mitigated by temperatures about 15 C. Movements and diving behavior of head-started loggerheads were different than wild turtles. Some head-started turtles entered the Gulf Stream and traveled eastward across the Atlantic, while others wandered in various directions. Head-started loggerheads made more (mean = 69) and shorter dives (mean = 21 min) over a 12 hr period than wild turtles, and spent significantly less time submerged (mean = 54%) than wild turtles.
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Marchiori, Erica. "Parasitic infections in sea turtles and cetaceans in Mediterranean Sea waters, with a focus on the Adriatic Sea." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3426708.
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Parasitic infections contribute to natural mortality in population of free ranging sea turtles and cetaceans worldwide. Notwithstanding all host-dependant factors influencing the outcomes of parasitic infections, some parasites, spanning from protozoan to helminthic taxa, have a high pathogenic potential and can cause fatal disease in these animals. Sea turtles blood flukes (Digenea: Spirorchiidae) are a main factor in mortality of populations of green and loggerhead turtles in Atlantic and Pacific Ocean. In order to explore presence and pathology of spirorchiidiasis in the Mediterranean area, data from 168 loggerhead turtles (Caretta caretta) stranded dead along North Western Adriatic coast were collected during a six-years period. Parasitological study and pathological findings revealed the presence of eggs and adult flukes of Hapalotrema mistroides and Neospirorchis – Neogen 11, with prevalence of 15.5% and 6.0% respectively. Mild lesions were observed, including multifocal granulomatous enteritis and chronic focal vasculitis of the major vessels. Egg emboli were found widespread in the tissues, mostly attributable to H. mistroides. Sequencing of rDNA markers (28S and ITS-2) and phylogenetic analyses revealed the identity of the Mediterranean isolates with Floridian specimens. Genetic analysis on the hosts led to the conclusion that the life cycles of both genera can be entirely supported by the Mediterranean ecosystem. To estimate the infection intensity, a new rapid method was set up. Correlation between spleen egg burden and fecal egg output was studied by means of statistical tests applied to splenic tissue and fecal material, revealing the absence of correlation and the unreliability of fecal burden to assess severity of the disease in vivo. Gastrointestinal helminth community of loggerheads was also studied, revealing a species diversity typical of demersal stage turtles and similar to that observed in other neritic areas of the Mediterranean.
As for cetaceans, crassicaudosis is considered one of most severe helminthic infections in these animals. Nevertheless, knowledge on the epidemiology of Crassicauda species is scarce, due to constraints of sampling free-ranging wild host species and to the difficulty of obtaining entire specimens suitable for morphologic studies. Presence and pathology of Crassicauda boopis were investigated in fin whales (Balaenoptera physalus) stranded along Italian coasts. Severe lesions linked to the presence of adult nematodes in circulatory system and kidneys were detected in five rorquals (5/7), associated with renal function impairment and arteritis of the mesenteric vessels linked to spirurid larvae migrans. Morphological studies enabled the identification of the adult nematodes as C. boopis. Sequencing of molecular barcode regions was performed on adult and larval nematodes from the whales; additionally, specimens of Crassicauda spp. isolated from toothed whales were morphologically and molecularly studied. A multigene analysis made on the barcode regions of rDNA and on the mtDNA revealed the ITS-2 spacer to be the most efficient marker in species differentiation inside the genus Crassicauda. This analysis opened new insights on the identity of the isolated larvae migrans and on the life cycles of these poorly known nematodes. Furthermore, during the parasitological examination, immature elements of the genus Pennella were recovered from one fin whale and described from a morphological point of view for the first time. Preliminary molecular data were obtained, with the aim of clarifying the taxonomy of the genus Pennella. The coccidian Toxoplasma gondii was detected in the tissues of one rorqual as well, likely associated with a chronic infection.
In conclusion, these parasitological surveys highlighted the importance of a continue monitoring of the health of these endangered species avoiding underestimating the potential impact of parasitic diseases in natural mortality.Le infestazioni parassitarie contribuiscono alla mortalità naturale in popolazioni di tartarughe marine e cetacei in tutto il mondo. A prescindere dai diversi fattori dipendenti dall’ospite che possono influenzare l’esito di tali infestazioni, alcuni parassiti, dai protozoi agli elminti, possiedono un alto potenziale patogeno, tale da essere causa primaria di morte. Infestazioni da Trematodi Digenei del sistema cardiocircolatorio (Digenea:Spirorchiidae) sono un’ importante causa di morbidità in popolazioni di tartarughe marine degli oceani Pacifico e Atlantico. Per indagare la presenza e la patologia di questa infestazione nel Mediterraneo, sono stati raccolti dati da 168 tartarughe Caretta caretta spiaggiate lungo la costa adriatica nord occidentale in un periodo di sei anni. L’approccio parassitologico, sia tradizionale che molecolare, e lo studio anatomopatologico hanno rivelato la presenza di uova e adulti di Hapalotrema mistroides e Neospirorchis – Neogen 11 con prevalenze di 15.5% e 6.0% rispettivamente. Sono state riscontrate lesioni lievi, tra cui enterite granulomatosa multifocale e vasculite cronica focale a carico dei grossi vasi. Il sequenziamento dei markers genomici (28S e ITS-2) e l’analisi filogenetica hanno permesso di verificare l’identità dei nostri campioni con quelli isolati in Florida. Analisi genetiche effettuate sugli ospiti hanno portato a concludere che il ciclo vitale di questi parassiti può completarsi all’interno del Mediterraneo. Un nuovo metodo rapido per la quantificazione dell’intensità di infestazione è stato quindi messo a punto. È stata studiata la correlazione tra l’emissione di uova nelle feci e la presenza di uova nei tessuti attraverso l’applicazione di test statistici, che hanno rivelato l’inattendibilità del valore della carica di uova fecali al fine di stimare la gravità dell’infestazione in vivo. Per quanto riguarda i cetacei, la crassicaudosi è una delle più gravi elmintiasi in questi animali ma ciononostante i dati sull’epidemiologia di Crassicauda spp. sono ancora scarsi, a causa delle limitazioni poste dal campionare queste specie ospite e alla difficoltà di ottenere campioni parassitologici integri. La presenza e la patologia della crassicaudosi sono state studiate in balenottere comuni (Balaenoptera physalus) spiaggiate lungo le coste italiane. Gravi lesioni collegate alla presenza di nematodi adulti nel sistema circolatorio e nei reni sono state trovate in cinque animali (5/7), in presenza di insufficienza renale in un caso e arterite dei vasi mesenterici associata alla presenza di larvae migrans di nematodi spiruridi. Gli studi morfologici, comparati con le descrizioni in letteratura, hanno permesso di identificare i parassiti adulti come Crassicauda boopis. Sono state sequenziate le regioni di barcoding sui parassiti adulti e sulle larve e, parallelamente, altri individui di Crassicauda spp., isolati da odontoceti, sono stati studiati morfologicamente e molecolarmente. Un’analisi multigenica sulle regioni barcode ha rivelato che il segmento ITS-2 si è rivelato il più efficiente nella distinzione di specie all’interno del genere Crassicauda. Questa analisi apre nuove questioni riguardo l’identità delle larve migrans e il ciclo vitale di questi nematodi. Durante l’esame parassitologico, elementi immaturi di Pennella spp. sono stati isolati da una balenottera e descritti morfologicamente per la prima volta. Dati molecolari preliminari sono stati ottenuti al fine di chiarire la tassonomia del genere Pennella. Toxoplasma gondii è stato isolato da un altro esemplare, associato a infezione cronica. I dati parassitologici raccolti hanno rivelato l’importanza di un continuo monitoraggio della salute di queste specie che tenga in considerazione il potenziale effetto delle parassitosi sulla mortalità naturale.
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Horton, Michael Scott. "Reproductive success of sea turtles nesting on Wabasso Beach, East-Central Florida." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/77902.
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During the summers of 1988 and 1989, nests of 528 loggerhead sea turtles (Caretta caretta), 27 green sea turtles (Chelonia mydas), and 1 leatherback sea turtle (Dermochelys coriacea) were monitored on Wabasso Beach in Indian River County, Florida. Two hundred and forty four of the loggerhead and 2 of the green sea turtle nests were marked during night surveys as the females laid their clutches, permitting exact clutch counts and carapace measurements on the nesting females. Each marked nest was inspected daily for signs of disturbance and hatching. After incubation (70 days), study nests were excavated and inventoried to determine hatchling emergence success. Parametric multiple regressions, nonparametric multiple regressions, and logistic regressions were used to determine the effects of several measured variables on clutch sizes and incubation times; and nesting, hatchling emergence success, and predation. Excluding the last 2 weeks of the nesting season, nesting was positively correlated with ocean temperatures (P< 0.05), but not with human beach-side development (P> 0.05). Nesting loggerheads on the study area had an average carapace length of 89.8 cm (S.E.=0.31), and a mean clutch size of 112 eggs (S.E.=1.07). Clutches required an average of 53.9 days (S.E.=0.21) to incubate during 1988, with a hatchling emergence success of 57%. During 1989, the mean incubation time and hatchling emergence success was 51.5 days (S.E.=0.21) and 44%, respectively. Over the 2 study years, the average green turtle nest had 118 eggs, took 54.6 days to incubate, and had a hatchling emergence success of 40%. During 1988, 4.6% of the loggerhead nests were lost to beach erosion or alteration (deposition of sand on nests by the surf). This loss was 22% during 1989 for loggerheads, and 30% over both years for green turtles. The difference in loggerhead losses over the 2 years was due to 2 late-season hurricanes which affected the area during 1989. Predation on loggerhead nests was 16% and 8% during 1988 and 1989, respectively. In both years, predation was positively correlated with human beach-side development (P<0.05); during 1989, predation also was positively correlated with distance of the nest from the beach dune (P< 0.05). Clutch size and carapace size of nesting females were positively correlated (P< 0.05). Incubation time was negatively correlated with egg laying date, and hatchling emergence success was strongly affected by the late summer storms of 1989. The study area produced an estimated 70,469 loggerhead sea turtle hatchlings per year (8,808 hatchlings/km), and 535 green sea turtle hatchlings per year (66 hatchlings/km). The number of loggerhead sea turtle hatchlings produced per nest was adversely affected by beach-side development.Master of Science
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Sapp, Adam. "Influence of small vessel operation and propulsion system on loggerhead sea turtle injuries." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33845.
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Loggerhead sea turtles (Caretta caretta) can be found worldwide, inhabiting tropical and subtropical coastal waters. The loggerhead was classified as an endangered species and placed on the International Union for Conservation of Nature and Natural Resources (IUCN) Red List in 1996 (IUCN 2006).The problem of sea turtle mortality as a result of collisions with vessels is of increasing concern, especially in the southeastern United States, where increased development along the coasts results in increased recreational boat traffic. In the United States, the percentage of strandings that were attributed to vessel strikes has increased from approximately 10% in the 1980's to a record high of 20.5% in 2004 (NMFS 2007).
This report presents results from field experiments designed to investigate the ways in which loggerhead sea turtles are injured in boat collisions, and the effectiveness of several mitigation options for reducing the risk of fatal interactions. In order to conduct these field experiments, a synthetic sea turtle carapace was designed and built that approximated the structural behavior of a biological sea turtle carapace. Hodges (2008) quantified the material strength properties of loggerhead sea turtle carapaces. From these results, it was determined that the target parameter for simulating tensile strength in a synthetic carapace should be force per unit width of sample. Hodges designed and constructed an artificial carapace made of composite material for use in controlled experiments.
Modifications were made to the design proposed by Hodges (2008) to facilitate rapid construction. Several designs were tested using the force per unit width as the target strength parameter and compared to the strength of the biological carapace. Tests on the design ultimately adopted showed a force per unit width 17.6% stronger than the biological carapace. The composite material being stronger than the biological carapace means the testing will result in conservative reports of damage. Once the design and construction methods were finalized, approximately 60 artificial carapaces were fabricated for field testing. A frame, weighting scheme and buoyancy unit were designed and fabricated so that each test carapace floated at proper draft and had realistic specific gravity and weight.
Field testing procedures were designed to investigate the influence of a) boat speed, b) animal position in the water column, and c) vessel propulsion system on the severity of vessel collisions on turtles. All experiments were done with small (<6 m in length) vessels. Boat/sea turtle collisions were simulated by placing a test specimen (a synthetic carapace attached to a test frame) in the water column and striking it with the vessel. The speeds considered were idle (7 km/h), sub-planing (14 km/h), and planing (40 km/hr). The two animal positions in the water column were 1) at the water surface and 2) at "prop depth" (depth to the center of the propeller hub on the standard outboard motor). Five propulsion options were tested: 1) a standard outboard motor, 2) a standard outboard motor with Hydroshield® propeller guard 3) a standard outboard motor with Prop Buddy® propeller guard, 4) a jet outboard motor and 5) a jet-propelled personal watercraft, often referred to generically as a "jet ski". The experiments typically included five trials per test configuration.
Catastrophic (presumably fatal) damage was defined to occur when any damage penetrated the carapace. Small wounds (< 4 cm in length) along the sides or rear of the artificial carapace, where the shell and bone extend beyond the edge of the body cavity, were not classified as catastrophic This definition was used to classify the effectiveness of the various mitigation options.
Results indicate that reducing the speed of the vessel reduces the odds of severe damage to the animals. Of all of the tests performed with the standard outboard motor (including tests with propeller guards installed), 25% of those performed at idle speed resulted in catastrophic damage, compared to 100% for planing speed tests. The two tested propeller guards both modified the type of damage to the animal when compared to similar tests with the standard motor configuration, but they only slightly reduced the risk of catastrophic damage. At idle speed, with propeller guard installed, 10% of the tests resulted in catastrophic damage. The corresponding number for the standard motor was 40%. At planing speed, 100% of the tests resulted in catastrophic damage, with or without the propeller guard.
No catastrophic injuries were observed during testing of both jet propulsion systems (jet outboard and jet ski) at any speed or depth in the water column. Both feature a much smaller draft than the standard outboard, which results in little chance of striking an animal below the surface. And both the jet outboard and the jet-powered watercraft feature water intakes that are relatively smooth and appeared to slide across the animal with minimal damage to the carapace when the model animal was floating on the surface.
The experiments described here involved a limited range of hull configurations; results may be different for hulls or propulsion systems drastically different than those tested here. But the results obtained indicate that equipment, in the form of the boat's propulsion system, and the mode in which it is used both play a role in defining the risk of boats to turtles in the field.
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Wabnitz, Colette Catherine Chantal. "Sea turtle conservation and ecosystem-based management with a focus on green turtles (Chelonia mydas) and seagrass beds." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/24239.
Full textAbstract:
The design of effective species management and recovery plans for sea turtle populations requires targets that are informed by an understanding of knowledge gained at the level of individuals/populations in the context of the wider goal of protecting an ecosystem's structural and functional attributes. In this thesis I present the first detailed investigation of the multiple levels at which sea turtles, particularly green turtles (Chelonia mydas), interact with ecosystems.
I begin by developing a framework for an age-structured population-level assessment of food consumption for hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta), and green turtles. This entailed construction of species-specific growth models for the western Atlantic, and subsequent integration of results with morphometric, survival, abundance, and food conversion efficiency to derive consumption estimates.
At the ecosystem level, I developed models for the Caribbean and Hawai’í, where green turtles are present at very low abundances and reaching carrying capacity, respectively. In the Caribbean, results showed that green turtle grazing of seagrass substantially altered habitat complexity, reducing the refuge role of seagrass to reef fish and invertebrates, and leading to potentially dramatic changes in species biomass and composition. In Hawai‘i, by feeding on algae, green turtles were found to contribute to the resilience of reefs in the face of disturbance, a functional role that needs to be explicitly included in future studies of reef dynamics. Taken together, these findings highlight the need to consider trophic and indirect interactions in the evaluation of sea turtles’ role within ecosystems.
Accurate and reliable estimates of foraging habitat extent are essential to inform realistic and sustainable turtle recovery targets, particularly given the current degraded state of coastal ecosystems. Using Landsat satellite imagery, I present a novel mapping approach for seagrass habitats at large scales. Such regional initiatives are also urgently needed if the international community is to meet aims to conserve 10 – 30 % of specific habitats. A comparison between reef extent, determined using remote sensing and existing data, showed that discrepancies ranged from + 1,316 % to - 64 %, underlining our limited ability to ascertain progress towards adopted global marine conservation targets based on current data.
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Searle, Linda. "Robinson Point, Belize: An Important Foraging Ground for Endangered Sea Turtles in the Western Caribbean Sea." NSUWorks, 2013. http://nsuworks.nova.edu/occ_stuetd/155.
Full textAbstract:
Anecdotal reports, flipper tag returns, satellite migration paths, and above-water and net surveys have identified an important foraging area for sea turtles in the Robinson Point area, 12 kilometers southwest of Belize City. Visual observations confirmed that sea turtles were actively foraging at Robinson Point. Sixteen 30 minute visual observations from stationary and drifting boats made 132 sea turtle sightings from October 2007 through January 2008, with a maximum of 40 sightings made in one survey. In-water capture methodology tested the traditional turtle net, which captured 14 turtles in 63 sets for a success rate of only 22%. There were 11 green turtles captured during the migratory months from April through October, and three hawksbill turtles were captured during non-migratory months, November through March, indicating that both species were resident at Robinson Point. No loggerheads, adult males, or juvenile turtles were captured, but anecdotal reports confirmed presence. Size range for captured hawksbills was between 63.7 - 80.4 cm SCLnn and between 70.9 - 91.5 cm SCLnn for green turtles. There were two recaptured turtles. One was a nesting hawksbill tagged in Mexico in 2008 and recaptured at Robinson Point in 2009, and the other was a sub adult hawksbill that was captured at Robinson Point in 2008 and recaptured in 2013 in Nicaragua. There was a small growth of fibropapilloma on one green turtle. Habitat surveys suggest benthic communities are more diverse than previously described consisting of prey items sought by sea turtles. Geomorphology of the Robinson Point area is equally diverse and provides shelter for resident turtles. Proposed boundaries for a turtle conservation zone at Robinson Point and an internesting zone to protect turtles at Belize premier hawksbill nesting beach at Gales Point, are linked to existing protected areas, and would facilitate protection of sea turtles not only in Belize, but also throughout the Caribbean.
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Nishizawa, Hideaki. "Study on Conservation Management of Sea Turtles by Using Genetic Information." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188860.
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Mansfield, Katherine Lamont. "Sources of mortality, movements and behavior of sea turtles in Virginia." W&M ScholarWorks, 2006. https://scholarworks.wm.edu/etd/1539616760.
Full textAbstract:
Aerial surveys are commonly used to evaluate in-water sea turtle abundances. A correction is applied to account for turtles diving below the observed surface. Historically, observations of summer/fall surfacing behavior were used for this correction, assuming constant behavior among seasons. Using radio/acoustic telemetry, seasonal differences in sea turtle surfacing behavior were determined among Kemp's ridleys and loggerheads. Mean time spent at surface in the spring ranged between 9.9%-30.0% with significant differences among individuals. Observed surfacing times were higher than historic summer/fall observations (Byles 1988; 5.3%), indicating that historic springtime abundances were overestimated by 50%-80%. Aerial surveys (2001-2004) indicated a 65%-75% decline in the Chesapeake Bay sea turtle population since the 1980's. Current sea turtle estimates range between 2,500-5,500 turtles compared to 6,500-9,000 turtles observed in the Lower Bay alone in the 1980's. Satellite telemetry was used to track long-term movements of adult and juvenile turtles utilizing Virginia's waters. Loggerheads and Kemp's ridleys were found to exhibit significant fidelity to Bay and coastal waters south to Cape Hatteras. Several individuals established winter habitat off Cape Hatteras, adjacent to the outer continental shelf and Gulf Stream. Fall migrations commenced when surface temperatures dropped below 20??C. Some turtles migrated south to Georgia, Florida and the Gulf of Mexico. Two turtles were transported by the Gulf Stream to the north Atlantic and the Grand Banks, indicating some plasticity in habitat use. Virginia's pound net fishery was considered a primary source of sea turtle mortality in the 1980's. Fisheries surveys (2000-2002) indicated a significant reductions in fishery effort and hazardous large mesh and string leaders. No subsurface bycatch mortalities were observed during side scan sonar surveys (2001-2002). Pound nets are no longer a significant source of sea turtle mortality in Virginia. Pound net recaptures of live turtles (1979-2002) indicated strong philopatry to specific foraging areas, including strong inter-annual site fidelity. Over 20% of tagged loggerheads were recaptured in study nets during 1-11 seasons. Satellite telemetry was used to track the movements of one adult loggerhead captured multiple times from 1999-2002. Home range analyses indicated a 73.9% overlap in the total range over a three-year period.
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Smith, Donald Thomas Jeremy. "The cranial morphology of fossil and living sea turtles (Cheloniidae, Dermochelyidae and Desmarochelyidae)." Thesis, Kingston University, 1989. http://eprints.kingston.ac.uk/20531/.
Full textAbstract:
Many of the early taxonomic studies of fossil sea turtles relied heavily on postcranial evidence. Both the Cheloniidae and Dermochelyidae were erected on detail of the shell and limbs. ‘Desmatochelys’ was originally described in part using cranial evidence, but later workers (Zangerl and Sloan, 1960) suppressed the family on evidence from the shell. Little in the way of comparative work has been undertaken using the cranial morphology of fossil or living forms. This is thought long overdue. The first bone by bone description of the living cheloniids has revealed a large number of taxonomically useful characters and a close relationship between the genera. However, a great deal of interspecific variation was noted. ‘Chelonia mydas’ is considered to format least three subspecies on cranial evidence. The newly described ‘Natator (Chelonia) depressa’ is thought distinct from other living forms. The Dermochelyidae are seen to be a very conservative group and a large number of cranial characters link fossil and living forms. The arterial circulation of Dermochelys is redescribed and the importance of the blood flow to the head for use by the salt secreting glands in electrolyte balance is shown to be important. The Desmatochelyidae is shown to be a family in its own right, and a number of other genera, notably ‘Rhinochelys’ and ‘Notochelone’, are thought members of the group. Many of the basicranial features identified by Gaffney in the 70s for other fossil groups have been shown to be of use in the taxonomic study of the families under review.
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Kochinsky, Lyle J. "The Effects of Iodophor Compound on Skin Lesion Disease in Sea Turtles." NSUWorks, 1989. http://nsuworks.nova.edu/occ_stuetd/80.
Full textAbstract:
The culture of sea turtles provides a means for reestablishing depleted natural populations through restocking and, at the same time, alleviates pressures of over-exploitation on existing populations. A major problem in the rearing of sea turtles is disease control, particularly skin-disease. Necrotic skin lesions develop within the initial months of raising hatchlings and usually result in death, if not treated. Unfortunately, most treatments for controlling skin diseases in sea turtles have proven to be ineffective and labor intensive.
The primary objective of this study was to determine the effectiveness of an iodophor compound (Vanodine™) and standard treatment (KMnO4) in the prevention and treatment of developing skin lesion disease observed in sea turtle aquaculture. Samples of skin lesions encountered in the culture of sea turtles were described and identified. Bacteria associated with these skin lesions were isolated, cultured, and identified.
To test the prophylaxis of the treatments three study groups (N=35) of Caretta caretta (loggerhead sea turtles) were randomly selected from a mixed group of hatchlings, from six egg clutches. One group served as a “control" and remained untreated. The other two groups were treated with (1) Vanodine at a final concentration of 1:10,000 (100 ppm) and (2) Potassium permanganate (KMnO4) at a concentration of 1:1,000 (1,000 ppm). In both treatment groups, chemicals were added directly to the water of the holding tanks and maintained for 8-10 hour intervals.
To confirm the prophylactic effect, the initially untreated and KMnO4 treated groups were switched to Vanodine treatment on the seventh week of the study and the turtles in the initially Vanodine treated group were removed from treatment. This cross-over experiment followed the same experimental protocol as the initial phase of the prophlactic study. In order to determine the effectiveness of Vanodine on already established skin lesions, untreated loggerhead sea turtles of approximately 4 months of age were ramdomly divided into two groups. One group remained untreated and another group was treated with Vanodine at a final concentration of 1:10,000 (100 ppm) for 8 to 10 hours daily. This procedure continued for seven weeks, at which time the untreated group was treated with Vanodine and treatment in the initially Vanodine treated group was terminated. This cross-over experiment was identical in procedure and duration to the initial treatment study.
The susceptibility for natural skin lesion development in hatchling loggerhead sea turtles had been reported to occur during the third to fourth month after hatching. In this study, skin lesions developed in the Vanodine and untreated groups during the fifth week of life: however, skin lesions occurred during the second week on the turtles exposed to KMnO4.
Vanodine inhibited skin and scute lesion development in sea turtle hatchlings. Turtles which had previously developed skin lesion disease were successfully treated with Vanodine. It is important to note that Vanodine did not inhibit all lesions but was significant in reducing lesions when compared to the untreated and KMnO4 treated groups.
More and larger skin lesions occurred in the KMnO4 group than in the untreated group. KMnO4 had been used as a standard treatment for skin lesion disease in sea turtles and is effective on some skin lesion types, if administered topically. In this study, the addition of KMnO4 to the water of the holding tank was not successful in the prevention of skin and scute lesions in newly hatched loggerhead sea turtles when compared to the untreated group of turtles.
Switching the KMnO4 group to Vanodine (week 7) resulted in a highy significant (P>0.9995) decreasing trend in skin lesion number and area. After the KMnO4 turtles were exposed to Vanodine, lesion number first increased for initial two weeks of treatment, but then declined at a substantial rate thereafter. Skin lesion area decreased throughout the study period. Visible KMnO4 staining and matting of necrotic tissue around established lesions persisted for about two weeks after treatment was switched. The flushing of residual KMnO4 in conjunction with regeneration of stain damaged tissue appeared to be required before Vanodine could effectively treat existing skin lesions.
Scute lesions, especially those associated with Salmonella sp., were eliminated by the exposure to Vanodine. Number and area of scute lesions in the prophylactic study, became significantly (p>0.9995) lower in the Vanodine treated group compared to the untreated group after six weeks of treatment and remained significantly different throughout the cross-over experiment.
Scute lesion number and area were greater in the KMnO4 group compared to the untreated group, with the difference becoming highly significant (P>0.9995) by week six. KMnO4 was not effective in controlling scute lesions when compared to the untreated and Vanodine treated groups.
Vanodine seems to have two important roles in controlling skin lesion disease in sea turtle culture. First, the biocidal properties of the iodophor cause a possible reduction in the microbial load infiltrating the lesions. Second, Vanodine treatment of the water in the holding facility permits sufficient time for lesion healing by inhibiting the invasion of “opportunistic” pathogens. It appears that “opportunistic” pathogens which invade the already open lesion cause the high morbidity and mortality associated with skin lesion diseases in hatchling sea turtles.
The procedure developed in this study for treating an entire group of sea turtles by administering the iodophor directly 'into the water of the holding facility is very efficient when compared to the labor intensive practice, utilized by many previous methods, in which turtles were treated individually. Vanodine's application to raising sea turtles affords a one-step procedure for administering the iodophor to the entire stock, and enhancing the hatchling survival rate.
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Glen, F. "Studies on the behaviour and ecology of hatching and adult sea turtles." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637062.
Full textAbstract:
The timing of emergence of green turtle (Chelonia mydas) hatchlings from their nest on two beaches on Ascension Island was monitored. Emergence of hatchlings predominantly occurred at night, and was inhibited by increasing temperatures at superficial sand depths. No single thermal cue was found to play a role during the emergence of loggerhead turtle (Caretta caretta) and green turtle hatchlings from their nests on Cyprus. No difference in temperature within loggerhead and green turtle clutches was observed in northern Cyprus and on Ascension Island. The magnitude of metabolic heating during the final third of incubation, was positively related to clutch volume. A comparison of body size and flipper size was carried out on green turtle hatchlings from Ascension Island and Cyprus. Ascension Island hatchlings were larger than hatchlings from Cyprus. Incubation temperature appeared to influence body size on Ascension Island, with higher temperatures producing smaller hatchlings. Rhythmic throat movements were recorded during the various nesting stages of green turtles on Ascension Island. Throat movements occurred consistently during the various stages, although were statistically lower during egg deposition. Female green turtles were weighed post oviposition during nesting at Ascension Island. Turtles were found to lose 0.22kgd-1, as they do not feed during their time at the island. A dichotomy in depth utilisation between green turtles during their interesting interval in Ascension Island and Cyprus was observed. This difference was attributed to differences in food availability at the two sites. Depth and swim speed during U-dives carried out by a green turtle were measured during the inter nesting period in Cyprus. Typically the turtle initially descended at a steep angle (around 60°) but as the dive continued this angle lessened until the turtle approached the seabed at an average angle of about 15°.
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Caldas, Patrício Ana Rita. "Ecology of the green sea turtle (Chelonia mydas L.) in a changing world." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/30061.
Full textAbstract:
Climate change is threatening biodiversity, causing populations and species to adapt, or otherwise, become extinct. Sea turtles have survived dramatic climate changes in the past, however, due to a history of intense human exploitation, and the current anthropogenic threats, their current resilience may be jeopardized. The main pursuits of this thesis were to i) evaluate the resistance of green turtles to predicted climate change impacts, using a globally significant rookery, in Poilão, Guinea-Bissau, as a case study; and ii) assess key population parameters to inform the conservation management of this resource. As the work developed I additionally had the opportunity to study the dynamics of an emerging disease in a juvenile foraging aggregation from Puerto Rico, which contributed to a broader understanding of resilience in this species. Specifically, I investigate the nest site selection behaviour of green turtles, their nesting environment, and the outcomes for their offspring, at Poilão, and apply this information to infer on the resilience of this population under future scenarios of climate change. I explore the connectivity established by the dispersal of post-hatchlings from Poilão, followed by their recruitment to foraging grounds, to set the geographical context of this major population. Lastly, I model the dynamics of Fibropapillomatosis, which affects juvenile green turtles globally, and examine the potential for disease recovery. The green turtle rookery in Poilão shows some resilience to expected climate change impacts. This significant population likely contributes to all juvenile foraging aggregations along the west coast of Africa, and to some extent to those in South America. Currently, green turtles are capable of recovery from Fibropapillomatosis, however, the incidence of disease may be enhanced by climate change.
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Brock, Kelly. "EFFECTS OF A SHORE PROTECTION PROJECT ON LOGGERHEAD AND GREEN TURTLE NESTING ACTIVITY AND REPRODUCTION IN BREVARD COUNTY, FLORID." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2946.
Full textAbstract:
Marine turtle reproductive success is strongly correlated with the stability and quality of the nesting environment. Because females show fidelity to key nesting beaches, the management and physical characteristics of these beaches directly affect future generations of marine turtles and may be essential for the recovery of these threatened and endangered species. The impacts of beach restoration on loggerhead turtles (Caretta caretta) and on green turtles (Chelonia mydas) were investigated. Previous studies concerning beach nourishment projects have focused on loggerhead turtles. I compared data between nourished and non-nourished areas and between loggerhead and green turtles. I found, at one season post-nourishment, negative effects on nesting success and no significant effect on reproductive success for both loggerheads and established the same relationships with green turtles. Physical attributes of the fill sand, which did not facilitate acute scarp formation or severe compaction, did not physically impede turtles in their attempts to nest. Instead, the decrease in nesting success was attributed to an absence of abiotic and or biotic factors that cue nesting behavior. The increase in loggerhead nesting success rates during the second season post-nourishment was attributed to the equilibration process of the seaward crest of the berm. After the beach was restored, both species of turtles placed nests significantly farther from the water in the nourished area than in the non-nourished area. Green turtles nested on or near the dune and loggerheads nested on the seaward crest of the berm. The tendency of loggerheads to nest closer to the water resulted in more loggerhead than green turtle nests being "washed out" by erosion during the equilibration process. There was a significant increase in hatching success only for loggerheads when wash outs were excluded, thus illustrating the importance of nest placement and the detrimental effects of the equilibration process to the reproductive success of loggerheads. A decrease in reproductive output occurred during the first season post-nourishment. The reduction in the estimated total number of hatchlings produced (reproductive output) was a consequence of decreased nesting success lowering nest numbers. This reduction demonstrates that, regardless of similar reproductive success rates, marine turtles incurred net losses during the first season following nourishment. These results further reveal the impacts of decreased nesting success and the importance of minimizing excessive non-nesting emergences associated with beach nourishment.M.S.
Department of Biology
Arts and Sciences
Biology
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Botha, Marié. "Nest site fidelity and nest site selection of loggerhead, Caretta Caretta, and leatherback, dermochelys coriacea, turtles in KwaZulu-Natal, South Africa." Thesis, Nelson Mandela Metropolitan University, 2010. http://hdl.handle.net/10948/1233.
Full textAbstract:
Loggerhead and leatherback sea turtles nest on the beaches of the north-eastern portion of Kwazulu-Natal within the iSimangaliso Wetland Park. Loggerheads place ~60 percent of all nests within an 8 km stretch of beach, whereas leatherbacks tend to space their nests more evenly along the entire length of the monitoring area. The study aimed to determine nest site fidelity of loggerheads and leatherbacks (using four decades of nesting data housed by Ezemvelo KZN Wildlife) and the factors that influence nest site selection of both species within the 56 km of turtle monitoring area (32N to 100S) and the 5 km area of high-density loggerhead nesting (0N to 12N). The effectiveness of nest site selection was then determined through the hatching success of loggerheads over the 5km area (0N to 12N). Results showed that loggerheads show a high degree of nest site fidelity (~3 km) with nest site fidelity of individuals increasing over subsequent seasons of nesting, as well as these individuals using the same stretches of beach for nesting (the most popular area being 1N to 4N for repeat nesters). Leatherbacks displayed nest site fidelity of ~9 km and this did not increase over successive seasons of nesting. In terms of nest site selection, loggerheads and leatherbacks both avoided areas where low shore rock was present, whereas both species preferred nesting on beaches of intermediate morphodynamic state. Leatherback nesting was significantly higher in areas with wider surf zones. Both species were able to surpass the high water mark when nesting as nests below this point would be almost certainly doomed. Hatching success of loggerheads was comparative to high (83 %) relative to other studies, however, nest success varied across the beach from beacon 1N to 12N. Areas where highest nest success was observed were not areas of highest nest density presumably due to artificial lighting. Results from this study increase our understanding of the evolutionary biology of loggerhead and leatherback turtles in South Africa and the effectiveness of loggerhead nest site selection through hatching success.
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Wang, Hui-Chen. "Trace metal uptake and accumulation pathways in Kemp's ridley sea turtles (Lepidochelys kempii)." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2413.
Full textAbstract:
Little is known of trace metal concentrations and their possible role in the
mortality of critically endangered Kemp??s ridley sea turtles (Lepidochelys kempii).
Research described herein characterized concentrations of seven trace metals ??
Ag, Cd, Cr, Cu, Hg, Pb and Zn ?? in the blood and carapace tissue of captive
Kemp??s ridleys for use in assessing levels of these metals in wild counterparts.
Concentrations of same trace metals were characterized in post-pelagic through
adult life stages of 127 wild Kemp??s ridleys captured from the Gulf of Mexico and
southeast Atlantic during 2000 to 2002. Blood, carapace, liver, kidney, and
muscle tissues from live and/or stranded Kemp??s ridleys were analyzed for the
aforementioned trace metals via graphite furnace atomic absorption
spectrophotometer and cold vapor atomic fluorescence techniques conducted
under class-100 clean laboratory conditions. Similar trace metal assessments
were conducted on blue crab (Callinectes sapidus) prey to determine the role of
food as a possible uptake pathway in Kemp??s ridleys.
Overall, trace metal levels in live, captive as well as wild ridleys were higher
in carapace tissue than in blood. Carapace concentrations of Ag, Cr and Hg in
Kemp??s ridleys across all post-pelagic life stages increased with increasing
straight carapace length (SCL). Carapace tissue of wild ridleys exhibited higher
Cr, Hg, and Pb levels than their blue crab prey, regardless of study area;
whereas, crabs yielded higher Ag and Cu concentrations. Dead stranded ridleys
yielded higher Ag, Cr, Hg, Pb, Zn levels in carapace tissue, whereas, their liver
exhibited higher Cd and Cu levels. This finding suggests carapace tissue could
serve as a suitable surrogate sample source for internal organs/tissues when
monitoring exposure of live Kemp??s ridleys to certain metals. The fact that larger,
stranded ridleys exhibited higher Ag, Cd, Hg, Pb and Zn levels than did their
smaller, live analogs from Texas and Louisiana implies that these older ridleys
had increased opportunities to accumulate higher metal concentrations in their
carapace tissue than did their younger conspecifics. This trend suggests that
carapace tissue has the potential to accumulate trace metals while blood-borne
concentrations reflect only recent exposure to trace metals.
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Okuyama, Junichi. "Study on conservation and enhancement of endangered sea turtles using animal behavioral information." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/135982.
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Finlayson, Kimberly. "Development, validation and application of an in vitro toxicological model for sea turtles." Thesis, Griffith University, 2018. http://hdl.handle.net/10072/381655.
Full textAbstract:
Chemical contaminants accumulate in marine megafauna globally, including sea turtles. Logistical and ethical constraints around exposure experiments using large, long-lived, and often threatened species, has limited our understanding of how these pollutants may affect wildlife. The knowledge gaps are outlined in a systematic quantitative literature review (Chapter 2), which found that in vitro bioassays offer an ethical, reproducible, and cost-effective alternative for investigating the effects of contaminants. The development of an in vitro toxicological model can provide important information for conservation and management. This thesis aimed to develop, validate and demonstrate the applicability of an in vitro model for sea turtles. Cell cultures were established from skin and internal organs of green sea turtles including heart, small intestine, ovary and liver. Important questions concerning individual variation (Chapter 3) and variation between tissue types (Chapter 4) were addressed to select an ideal cell culture for further testing and validation. Variation in cytotoxic response was generally low between cell cultures established from different individuals. This suggests that one cell line can be used representatively. However the results highlight the importance of preliminary analysis in order to select a cell culture with an average response and this chapter provides a framework for doing so. Variation in cytotoxic response between tissue types was also generally low, though a clear pattern in organ sensitivity was apparent. This pattern identified skin as the most sensitive tissue type. This is particularly useful for future research, as skin can more readily be obtained from live, healthy turtles. Based on the results from Chapter 3 and 4, an ideal cell culture was selected for continued use. The usefulness of the selected cell culture was validated in two additional bioassays measuring oxidative stress and genotoxicity to test the effects of 16 model compounds (Chapter 5). Oxidative stress was measured through the formation of reactive oxygen species and genotoxicity was measured through the formation of a micronucleus. The results from cytotoxicity (Chapter 4), oxidative stress and genotoxicity assays (Chapter 5) were used in a screening risk assessment for wild turtle populations based on contaminant accumulation data from the literature. These screening risk assessments identified a number of locations where turtles may be at risk from current contaminant concentrations. Finally, the applicability of the in vitro model to broader ecological questions was demonstrated (Chapter 6). Blood extracts of turtles from three different foraging grounds were used in the bioassays to examine differences in exposure. This data, along with chemical analysis of trace elements, was used to assess risk from chemical exposure to these populations. Blood extracts from Moreton Bay turtles caused significantly stronger responses in both the cytotoxicity assay and oxidative stress assay, both of which were important factors contributing to differences between foraging grounds when combined with trace element data. The measured effect concentrations for blood extracts from Moreton Bay turtles were approximately half the concentration found in blood, indicating a higher risk associated with chemicals in blood from turtles in Moreton Bay compared to the other sites monitored. These results illustrate that using in vitro bioassay data can provide unique information into exposure and effects in sea turtles, and this data can be used to identify and prioritise populations at risk. This thesis has demonstrated that species-specific in vitro methods are suitable and useful in identifying chemical risk to sea turtles. In vitro methods can be used to understand the molecular initiating events of chemicals in sea turtles, data from these studies can be used in screening risk assessments, and finally, in vitro models can be used with biological samples to assess current concentrations and mixtures of contaminants. Altogether, species-specific in vitro models offer a promising avenue for sea turtles and other marine megafauna as well.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Jones, William Mason. "Physical Parameters Affecting Incubating Temperatures in Loggerhead Sea Turtles, Caretta caretta, in Virginia." W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539617732.
Full textAbstract:
Detailed physical profile of eight transplanted loggerhead sea turtle, Caretta caretta, nests were obtained from Virginia and northeastern North Carolina and reburied in Back Bay National Wildlife Refuge (BBNWR), Virginia Beach, Virginia during the summers of 1987, '88, and '89 to determine if the physical location of the egg within the nest had an affect on sex determination. Transplanted nests were reburied in sandy substrate at a depth of 15-60 em on south facing dunes, and a Campbell Scientific data-logger logged synchronously environmental data. The following data were collected: temperatures at various locations within a nest, net absorbed radiation, ambient temperature, rainfall (em), substrate moisture content, and tide cycles. To understand the determination of sex, a time series analyses was employed to explain the variability, the periodicity, and the irregular oscillations of the temperature data. The regression analysis, using the periodicity of the spring/neap cycles, indicated a significant diurnal and spring/neap tidal affect. The 29.5 and 14.7 day cycle were significant. In addition, a delayed heating affect on the dune temperatures was noted 3-5 days after the lowest tides of the full and new moon cycles which consistently occurred at approximately 3:00P.M. Temperature records in nests at BBNWR were consistent with those producing a predominance of male hatchlings (<28.0C). Temperatures which produced females did exist, but were infrequent. Maximum beach face heating resulted in elevating · temperatures from 1-3C at the 37cm depths. This affect could produce females in late summer and early fall. Physical parameters varied with depth, time of day, and season (summer/fall). The results of this study are important to conservation of sea turtles because they contribute much to the knowledge of how nest manipulation may control sex ratios. Using the approach developed in this study, a mathematical model to predict sex ratios could be developed that would be applicable for various physical regimes found on most major nesting beaches of various sea turtles around the world.
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Roncari, Chiara. "Evaluation of microplastic content in faecal sample from hospitalized loggerhead sea turtles (Caretta caretta) of the North Adriatic Sea." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20386/.
Full textAbstract:
Microplastics represent persistent and highly dispersal pollutants in the marine environment. The knowledge about ingestion and relative effects in large marine vertebrates, such as sea turtles, is still fragmentary. To date, studies on MP accumulation in these animals were based on the analysis of gastrointestinal tracts obtained after necropsy. In this study, we developed a protocol that allows the study of the MP through faecal material from alive turtles, that can be used in rescue centres in several locations. Specifically, faecal samples from 45 specimens of Caretta caretta, rescued along the coast of Emilia-Romagna and Marche (Italy) from 2016 to 2019 were assessed for MP content through different hospitalization periods. A unique sample was collected from 24 animals, while for 21 specimens two samples were obtained. This allowed us to quantify and characterize the MPs and to evaluate putative differences in the excreted particles during the hospitalization period.
All individuals showed MPs in the faeces, for an average value of 6 ± 6.09 particles/animal. The maximum number of particles found in a single individual is 34 MPs. Filamentous particles were the most represented shape and transparent/white and red colours prevailed over the other colours.
Analyses of data about first sampling show a significant negative correlation between MP number and turtle’s size. This could be due to the different feeding behaviours that occur in these animals according to their life stage. The absence of significant differences between classes and categories of shape and colours particles could be due to the high contamination of the preys in the Adriatic Sea.
The absence of significant differences between the first and second sampling (where available), suggests that during the hospitalization period there might have been external influences that affected the results, including MP intake with diet, which would be considered in future studies.
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Mellet, Bernice. "Ecological risk assessment of fisheries on sea turtles in the South Western Indian Ocean." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/9957.
Full textAbstract:
The SWIO is an area of great biodiversity and included in the diverse species that occupy the region are five species of sea turtles that include green turtles, hawksbills, leatherbacks, loggerheads and olive ridleys. Despite considerable conservation efforts at sea turtle rookeries in the South Western Indian Ocean, only green and loggerhead turtle populations have shown an increase in population size in recent years (<10 years), whereas leatherbacks remained stable and hawksbills and olive ridleys declined. This begs the question if fisheries (or other offshore pressures) are responsible for slowing the recovery of these populations in the region, and if so, which specific fisheries are responsible for this trend? Several offshore (mostly industrial) and coastal (mostly artisanal) fisheries overlap with sea turtle distribution at sea. Industrial fisheries that are globally known to have a demonstrable impact on sea turtle populations are longline and to a lesser extent purse seine fisheries, whilst prawn trawl, gillnet and beach seine fisheries are coastal fisheries with a known negative impact on sea turtle populations. Holistic conservation strategies should be developed that include both land and sea protection for sea turtle species. It is thus necessary to identify and manage offshore threats including fisheries activities, particularly those fisheries that are showing the highest risk to sea turtle populations. This prompted an investigation into the bycatch rates and mortality of all sea turtle species that occur in the SWIO region in several offshore and coastal fisheries including both industrial (longline, purse seine and prawn trawl) and artisanal (including gillnet and beach seine) fisheries. The specific aims were (i) to identify and quantify the interactions (and if possible mortality) of sea turtle species in fisheries and (ii) to identify vulnerable species/populations to fishing operations using a semi-quantitative Ecological Risk Assessment (ERA) in the form of a Productivity-Susceptibility Analysis (PSA). Published information, online databases and technical reports were used as data sources to establish a database containing essential information regarding fishing effort and sea turtle bycatch in the region. The existing information was used to map fisheries extent and effort within the region, and to perform bycatch calculations. Interactions and mortality rates for sea turtles in five fisheries were quantified using bycatch rates from regional studies. Between 2000 – 2011, industrial longline and purse seine fisheries captured sea turtles at a rate of 4 388 indiv.y-1, with the mortality rate being 189 indiv.y-1. The bulk of these interactions were in the longline industry that captured 4 129 ± 1 376 indiv.y-1, with a corresponding mortality rate of 167 ± 53 indiv.y-1. The most commonly caught species (in longlines) were loggerheads and leatherback turtles, but the greatest impact is expected to be on the leatherback population due to the high interaction rate relative to population size. The bycatch (259 ± 34 indiv.y-1) and mortality (20 ± 2 indiv.y-1) rates of sea turtles in the purse seine fishery was considerably lower than the longline fishery. The purse seine fishery thus does not seem to have a significant impact on sea turtle populations in the SWIO. The impact of all forms of fish aggregation devices were excluded from the analysis as the impacts of these are poorly documented. Coastal prawn trawl, gillnet and beach seine fisheries captured an estimate of between 50 164 - 52 370 indiv.y-1 from 2000-2011. The highest bycatch rate was estimated for gillnet fisheries (40 264 indiv.y-1) followed by beach seine fisheries (9 171 indiv.y-1) and prawn trawl fisheries (at 1089 – 2795 indiv.y-1). The gillnet fishery could be responsible for slowing the recovery rate of green turtle and leatherback populations in the SWIO due to the high capture rates in this fishery compared to the population sizes of the species. Beach seine and prawn trawl fisheries are not expected to be hamper the recovery rate of any of the populations in the SWIO due to the low levels of interactions and low mortality rates compared to the population sizes. There are however very few data available regarding the bycatch of sea turtle species within these fisheries, highlighting the need for further research regarding this. A productivity-Susceptibility Analysis (PSA) was used to evaluate the relative vulnerability of species to fisheries, and is frequently applied in data poor situations. Limited data on sea turtle life history characteristics and population dynamics of species in the SWIO prompted the use of a PSA to determine the species most vulnerable to fisheries in the region. Results of the PSA indicated that gillnet fisheries poses the largest fishery-related threat to sea turtle populations, specifically the green and leatherback populations. The longline fishery that poses a particular threat to the leatherback population in the SWIO is also a particular concern. A cumulative impact assessment (combining fisheries and other threats) indicated that the SWIO leatherback population is extremely vulnerable to the combination of threats that influence this population in the SWIO. Even though individual fisheries may pose a small threat, the cumulative impacts of the fisheries can lead to severe impacts on populations such as slowing the recovery rate of populations. There are however significant data gaps that require attention in order to fully assess the impact of these fisheries on sea turtle populations. Despite the fact that fisheries are not implicated as a mayor reason for the decline in the hawksbill and olive ridley populations in the region, these two species are in decline indicating that there are other factors responsible for the decline not yet identified. It however remains imperative to reduce the mortality from all sources to ensure the continued viability of sea turtle populations in the region.
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Cheung, Sze-man, and 張思敏. "Ecology, conservation and trade of freshwater turtles in Hong Kong andSouthern China, with particular reference to the critically endangeredCuora trifasciata." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B45015739.
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au, Pendoley@newton dialix com, and Kellie Lee Pendoley. "Sea Turtles and the Environmental Management of Industrial Activities in North West Western Australia." Murdoch University, 2005. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20060612.120104.
Full textAbstract:
The nesting demographics of sea turtles using beaches within the Barrow, Lowendal,
Montebello (B-L-M) island complex on the North West Shelf of Western Australia were
examined in the context of their spatial and temporal distribution and potential for
exposure to industrially based artificial light sources. The distribution of overnight turtle
tracks throughout the island complex confirmed high density nesting of Chelonia mydas
(green turtles) on deep, sandy and high energy beaches and Natator depressus
(flatback turtles) on deep, sandy and low energy beaches, while Eretmochelys
imbricata (hawksbill turtle) tracks were most visible on shallow, sandy beaches
adjacent to near shore coral reef habitat. The three species exhibited a summer
nesting peak. Hawksbill turtles commenced nesting in September and continued
through to January, green turtles commenced in November and decreased in March.
Flatback turtles displayed the most constrained nesting season reported to date in
Australia with 86% of the animals visits recorded in December and January only.
Nesting population sizes estimated for the three species suggest that on a national
scale the B-L-M complex is a moderately large green turtle and a large flatback rookery
site. The hawksbill rookery is large on an international scale. While none of the green
turtle nesting beaches fell within a 1.5 km radius of industrially based artificial light
sources an estimated 42% of nesting flatback turtles and 12% of nesting hawksbill
turtles were potentially exposed to these light sources.
Testing of green turtle and hawksbill hatchling response to different wavelengths of
light indicate that hatchlings from the B-L-M region respond to low wavelength much
like hatchlings tested in North America (Witherington 1992a). Flatback hatchlings
displayed a similar preference for low wavelength light however their responses to
discrete light wavelengths between 400 nm and 700 nm suggest that this species may
not discriminate well between wavelengths that lie between 450 nm and 550 nm. This
response may be related to the rapid attenuation of visible light that occurs in the turbid
near shore habitats favoured by this species.
Field based arena studies carried out to investigate hatchling behaviour on nesting
beaches with light types commonly used in industrial settings found green turtle and
flatback hatchlings are significantly attracted to these lights compared to controls.
Lights that emit strongly in the low wavelength range (i.e. metal halide and fluorescent)
caused hatchling misorientation at lower intensities than the test light that emitted
relatively poorly in this range (high pressure sodium vapour). Hawksbill hatchlings
tested in situ under the influence of actual oil and gas onshore and offshore facility
based lighting were disrupted from the most direct line to the ocean by these light
emissions. Emergence fan mapping methods that measure hatchling orientation on
nesting beaches were refined and are proposed as an alternative monitoring tool for
use on beaches that are logistically difficult to access for large scale experimental
orientation studies. The hatchling behaviour was clearly complicated by beach
topography and moon phase.
Satellite tracking of post nesting female green and hawksbill turtles from North West
Shelf rookeries has identified the Western Australian location of migratory corridors and
foraging grounds for these species while Scott Reef turtles migrate from their south
Timor Sea rookery to Northern Territory waters. Green turtle nesting on Barrow Island
and Sandy Island (Scott Reef) forage at feeding grounds 200 1000 km from their
nesting beaches. Hawksbill turtles nesting at Varanus Island and Rosemary Islands
forage at locations 50 450 km from their nesting beaches. While all of the nesting
beaches within the B-L-M island complex are protected under the Barrow-Montebello
Marine Conservation Reserves, the only foraging ground similarly protected is the
Northern Territory foraging ground used by Scott Reef green turtles. None of the
foraging grounds used by North West Shelf green or hawksbill turtles is currently
protected by conservation reserves.