|
|
1989 Records 80 Pages Open / Close all records
| ID |
Full Title |
Author   |
Year |
PDF |
| 2014 |
Long-term decline of the western Pacific leatherback, Dermochelys coriacea: a globally important sea turtle population |
Tapilatu RF, Dutton PH, Tiwari M, Wibbels T, Ferdinandus HV, Iwanggin WG, Nugroho BH |
2013 |
639 KB |
|
KEYWORDS: Bird’s Head Peninsula, Papua Barat, Indonesia, conservation, decline, Dermochelys coriacea, leatherback sea turtle, nesting trend, western Pacific |
|
ABSTRACT: The leatherbacks nesting at Bird’s Head Peninsula, Papua Barat, Indonesia, account for 75% of the total leatherback nesting in the western Pacific and represent the last sizeable nesting population in the entire Pacific. Sporadic nest counts at Jamursba Medi Beach at Bird’s Head have indicated a declining trend from the 1980s through 2004, although a relatively high amount of nesting has recently been documented at Wermon Beach, located 30 km east of Jamursba Medi. We used expanded year-round nesting surveys from 2005 to 2011 at these two primary nesting beaches to obtain more robust estimates of the nesting population size and to evaluate long-term nesting trends. We found a 29% decline in nesting at Jamursba Medi and a 52% decline at Wermon from 2005 through 2011. We found that the estimated annual number of nests at Jamursba Medi has declined 78.3% over the past 27 years (5.5% annual rate of decline) from 14, 522 in 1984 to 1, 596 in 2011. Nesting at Wermon has been monitored since 2002 and has declined 62.8% (11.6% annual rate of decline) from 2, 994 nests in 2002 to 1, 096 in 2011. Collectively, our findings indicate a continual and significant long term nesting decline of 5.9% per year at these primary western Pacific beaches since 1984. Mark-recapture with PIT tags, initiated in 2003, resulted in the tagging of 1, 371 individual nesting females as of March 2012. Observed clutch frequencies ranged from 3-10 per season with a mean of 5.5 6 1.6 and, based on nest counts, provide an estimate of approximately 489 females nesting in 2011. The persistent and long term decline we report for the Bird’s Head leatherback population follows other dramatic declines and extinctions of leatherback populations throughout the Pacific over the last 30 years. These findings highlight the urgent need for continued and enhanced conservation and management efforts to prevent the collapse of what might be the last remaining stronghold for leatherbacks in the Pacific.
EXTERNAL LINK
|
|
| 2016 |
Resilience of marine turtle regional management units to climate change |
Fuentes, M. M. P. B., Pike, D. A., Dimatteo, A., Wallace, B. P. |
2013 |
N/A
|
|
|
KEYWORDS: Climate change adaptation, Conservation planning, Expert opinion, Flatback turtle, Green turtle, Hawksbill turtle, Leatherback turtle, Loggerhead turtle, Olive ridley turtle, Sea turtle |
|
ABSTRACT: Enhancing species resilience to changing environmental conditions is often suggested as a climate change adaptation strategy. To effectively achieve this, it is necessary first to understand the factors that determine species resilience, and their relative importance in shaping the ability of species to adjust to the complexities of environmental change. This is an extremely challenging task because it requires comprehensive information on species traits. We explored the resilience of 58 marine turtle regional management units (RMUs) to climate change, encompassing all seven species of marine turtles worldwide. We used expert opinion from the IUCN-SSC Marine Turtle Specialist Group (n = 33 respondents) to develop a Resilience Index, which considered qualitative characteristics of each RMU (relative population size, rookery vulnerability, and genetic diversity) and non climate-related threats (fisheries, take, coastal development, and pollution/pathogens). Our expert panel perceived rookery vulnerability (the likelihood of functional rookeries becoming extirpated) and non climate-related threats as having the greatest influence on resilience of RMUs to climate change. We identified the world's 13 least resilient marine turtle RMUs to climate change, which are distributed within all three major ocean basins and include six of the world's seven species of marine turtle. Our study provides the first look at inter- and intra-species variation in resilience to climate change and highlights the need to devise metrics that measure resilience directly. We suggest that this approach can be widely used to help prioritize future actions that increase species resilience to climate change.
EXTERNAL LINK
|
|
| 2018 |
Are Coastal Protected Areas Always Effective in Achieving Population Recovery for Nesting Sea Turtles? |
Nel, R., Punt, A. E., Hughes, G. R. |
2013 |
|
|
|
KEYWORDS: Marine Protection Areas, Population, Management, Loggerhead (Caretta caretta), Leatherback (Dermochelys coriacea), MPA |
|
ABSTRACT: Sea turtles are highly migratory and usually dispersed, but aggregate off beaches during the nesting season, rendering them vulnerable to coastal threats. Consequently, coastal Marine Protection Areas (MPAs) have been used to facilitate the recovery of turtle populations, but the effectiveness of these programs is uncertain as most have been operating for less than a single turtle generation (or<20 yr). South Africa, however, hosts one of the longest running conservation programs, protecting nesting loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) turtles since 1963 in a series of coastal MPAs. This provides a unique opportunity to evaluate the long-term effect of spatial protection on the abundance of two highly migratory turtle species with different life history characteristics. Population responses were assessed by modeling the number of nests over time in an index area (13 km) and an expanded monitoring area (53 km) with varying survey effort. Loggerhead abundance increased dramatically from~250 to>1700 nests pa (index area) especially over the last decade, while leatherback abundance increased initially~10 to 70 nests pa (index area), but then stabilized. Although leatherbacks have higher reproductive output per female and comparable remigration periods and hatching success to loggerheads, the leatherback population failed to expand. Our results suggest that coastal MPAs can work but do not guarantee the recovery of sea turtle populations as pressures change over time. Causes considered for the lack of population growth include factors in the MPA (expansion into unmonitored areas or incubation environment) of outside of the MPA (including carrying capacity and fishing mortality). Conservation areas for migratory species thus require careful design to account for species-specific needs, and need to be monitored to keep track of changing pressures.
EXTERNAL LINK
|
|
| 1941 |
Orientation of migrating leatherback turtles in relation to ocean currents |
Gallia S, Gasparb P, Fossettec S, Calmettesb B, Haysc GC, Lutjeharmsd JRE, Luschi P |
2012 |
N/A
|
|
|
KEYWORDS: Dermochelys coriacea, drift, leatherback sea turtle, migration, navigation, swimming speed |
|
ABSTRACT: During their offshore movements, leatherback turtles, Dermochelys coriacea, associate frequently with ocean currents and mesoscale oceanographic features such as eddies, and their movements are often in accordance with the current flow. To investigate how individual turtles oriented their ground- and water-related movements in relation to the currents encountered on their journeys, we used oceanographic techniques to estimate the direction and intensity of ocean currents along the course of 15 leatherbacks tracked by satellite during their long-distance movements in the Indian and Atlantic Oceans. For all individuals a non-negligible component of active swimming was evident throughout the journeys, even when their routes closely followed the currents, but overall the turtle water-related orientation was random with respect to current directions. For turtles in the North Atlantic, the ground-related movements largely derived from the turtles' active swimming, while in the Indian Ocean currents contributed substantially to the observed movements. The same pattern was shown when distinct parts of the routes corresponding to foraging bouts and travelling segments were considered separately. These findings substantiate previous qualitative observations of leatherback movements, by revealing that turtles were not simply drifting passively but rather swam actively during most of their journeys, although with a random orientation with respect to currents. Our analysis did not provide any indication that leatherbacks were able to detect the current drift they were exposed to, further highlighting the navigational challenges they face in their oceanic wanderings.
EXTERNAL LINK
|
|
| 1942 |
Nesting Phenology of Marine Turtles: Insights from a Regional Comparative Analysis on Green Turtle (Chelonia mydas) |
Dalleau M, Ciccione S, Mortimer JA, Garnier J, Benhamou S, Bourjea J |
2012 |
N/A
|
|
|
KEYWORDS: |
|
ABSTRACT: Changes in phenology, the timing of seasonal activities, are among the most frequently observed responses to environmental disturbances and in marine species are known to occur in response to climate changes that directly affects ocean temperature, biogeochemical composition and sea level. We examined nesting seasonality data from long-term studies at 8 green turtle (Chelonia mydas) rookeries that include 21 specific nesting sites in the South-West Indian Ocean (SWIO). We demonstrated that temperature drives patterns of nesting seasonality at the regional scale. We found a significant correlation between mean annual Sea Surface Temperature (SST) and dates of peak nesting with rookeries exposed to higher SST having a delayed nesting peak. This supports the hypothesis that temperature is the main factor determining peak nesting dates. We also demonstrated a spatial synchrony in nesting activity amongst multiple rookeries in the northern part of the SWIO (Aldabra, Glorieuses, Mohéli, Mayotte) but not with the eastern and southern rookeries (Europa, Tromelin), differences which could be attributed to females with sharply different adult foraging conditions. However, we did not detect a temporal trend in the nesting peak date over the study period or an inter-annual relation between nesting peak date and SST. The findings of our study provide a better understanding of the processes that drive marine species phenology. The findings will also help to predict their ability to cope with climate change and other environmental perturbations. Despite demonstrating this spatial shift in nesting phenology, no trend in the alteration of nesting dates over more than 20 years was found.
EXTERNAL LINK
|
|
| 1948 |
EU Purse Seine Fishery Interaction with Marine Turtles in the Atlantic and Indian Oceans: A 15 Years Analyses |
Clermont S, Chavance P, Delgado A, Murua H, Ruiz J, Ciccione S, Bourjea J |
2012 |
2.2 MB |
|
|
KEYWORDS: European tuna fishery, purse seine, marine turtle, bycatch, Atlantic, Indian Oceans |
|
ABSTRACT: Bycatch of marine turtles, vulnerable or endangered species, is a growing issue of all fisheries, including oceanic purse-seine fishery. The present paper seeks to assess marine turtle bycatch at a spatial and temporal level in the European purse seine fishery operating in the Atlantic and Indian Oceans. The study was based on data collected through French and Spanish observer programs from 1995 to 2011, a period where more than 230 000 fishing sets were realized by the UE fleets in both oceans. A total of 15 913 fishing sets were observed, including 6 515 on drifting Fish Aggregating Devices (FAD) and 9 398 on Free Swimming Schools (FSC), representing a global coverage of 10.3% in the AO and 5.1% in the IO. Over the study period, 597 turtles were caught during set observations, 86% being released alive at sea. At the same time, from 2003 to 2011, 14 124 specific observations were carried out on floating objects whether they ended in a set or not. 354 marine turtles were observed upon which 80% were already free or entangled alive and therefore released alive. At the temporal and spatial level, data were organized and analysed by ocean, fishing mode (FAD vs. FSC) as well as by year, quarter and statistical square of 1°. In order to evaluate the impact of this fishery in both oceans, bycatch distribution was compared to the total fishing effort of the UE fleet, as well as to the known marine turtle post nesting migration routes, nesting population abundances and known feeding areas. The species composition, the size and sex structure of bycatch are also discussed here. At last, an attempt to raise the data to the total fishing effort was carried out. Based on observation of marine turtle by-catches on sets, we estimated that, globally, 3500 marine turtles were accidentally captured by the EU-PS fleet in the Atlantic Ocean from 1995 to 2010, and around 2000 in the Indian Ocean from 2003 to 2010, with a corresponding annual bycatch rate of 218 (SD=150) and 250 (SD=157), with 91 and 77% being released alive, respectively in the Atlantic and Indian Ocean. However, because of important uncertainties mainly due to the low observation coverage and the scarcity of marine turtle bycatch events, it was impossible to produce solid and reliable global estimates of marine turtle bycatch and mortality due to PS activity. |
|
| 1984 |
Somatic growth rates of hawksbill turtles Eretmochelys imbricata in a northern Great Barrier Reef foraging area |
Bell I, Pike DA |
2012 |
434 KB |
|
|
KEYWORDS: Eretmochelys imbricata, growth rate, mark-recapture, sea turtles, sex-specific growth |
|
ABSTRACT: An understanding of the rate at which long-lived species grow is essential for determining important life history parameters, including assessments of foraging habitat quality, the time taken to reach sexual maturity, and the age at which maturity is reached. The hawksbill sea turtle Eretmochelys imbricata is a Critically Endangered species that is typically associated with coral reefs throughout the tropical oceans. Little is known about its life history through most age-classes, especially in the western Pacific, one of the last strongholds for the species. We undertook annual surveys of a foraging population of hawksbill turtles on 13 reefs, within the far northern section of the Great Barrier Reef (GBR), from 1997 to 2008. We obtained growth rate data from 128 turtles that were recaptured once (n = 103), twice (n = 23), or 3 times (n = 2). The curved carapace length of recaptured turtles ranged from 61.3 to 91.4 cm (x= 79.8 ± 7.26 cm, mean ± SD). Recapture intervals spanned between 11 and 120 mo (mean: 59 mo, median: 72 mo). We show that mean annual growth rates did not differ between sexes and had a non-monotonic growth pattern, reaching peak growth for both sexes within the 65 to 70 cm curved carapace length size-class. Growth slowed thereafter at a linear rate, to negligible growth upon reaching an adult size of >80 cm. Hawksbill turtles grew faster in the southern GBR, compared to those found in the far north of the reef. Understanding spatial and temporal differences in growth rates, and thus age at maturity, is an important step towards resolving life history differences among sea turtle populations. |
|
| 1999 |
Effects of off-road vehicle tyre ruts on the beach dispersal of green sea turtle Chelonia mydas hatchlings |
van de Merwe JP, West EJ, Ibrahim K |
2012 |
N/A
|
|
|
KEYWORDS: Tyre ruts, 4-wheel drive, off-road vehicle, ORV, recreational activity, nesting, endangered species, turtle, seafinding, hatchling |
|
ABSTRACT: The use of off-road vehicles (ORVs) on sandy beaches creates ruts in the sand that may interfere with the beach dispersal of sea turtle hatchlings. The present study investigated the influence of simulated ORV ruts of 3 depths (5, 10 and 15 cm) on the success and speed of green sea turtle Chelonia mydas hatchling dispersal. Almost all hatchlings (91%) were unable to traverse a single 15 cm rut, indicating that ruts of this depth are particularly detrimental to hatchling dispersal. Hatchlings had greater success traversing the 5 and 10 cm ruts, although they spent 2.6 and 18.6 times longer to get through a single rut, respectively (compared to the flat sand control path). It took progressively longer to get through subsequent ruts, and 99 and 53% of the hatchlings crawled along the 10 and 5 cm ruts, respectively, instead of attempting to crawl out of them. It was estimated that if hatchlings had to traverse 100 ORV ruts during dispersal, it would take 1.9 and 25.1 h for 5 and 10 cm deep ruts, respectively. The results from the present study indicate that green sea turtle hatchlings would spend considerable time navigating through ORV ruts, even as shallow as 5 cm, resulting in increased exposure to predation, dehydration and energy expenditure during this initial stage of dispersal.
EXTERNAL LINK
|
|
| 2001 |
Coastal light pollution and marine turtles: assessing the magnitude of the problem |
Kamrowski RL, Limpus C, Moloney J, Hamann M |
2012 |
399 KB |
|
|
KEYWORDS: Artificial light, Orientation, Coastal development, GIS analysis, Vulnerability assessment |
|
ABSTRACT: Globally significant numbers of marine turtles nest on Australian beaches, however, the human population of Australia is also heavily concentrated around coastal areas. Coastal development brings with it increases in artificial light. Since turtles are vulnerable to disorientation from artificial light adjacent to nesting areas, the mitigation of disruption caused by light pollution has become an important component of marine turtle conservation strategies in Australia. However, marine turtles are faced with a multitude of anthropogenic threats and managers need to prioritise impacts to ensure limited conservation resources can result in adequate protection of turtles. Knowledge of the extent to which nesting areas may be vulnerable to light pollution is essential to guide management strategies. We use geographical information system analysis to over-lay turtle nesting data onto night-time lights data produced by the NOAA National Geophysical Data Center, to assess the proportion of marine turtles in Australia potentially at risk from light pollution. We also identify the Australian nesting sites which may face the greatest threat from artificial light. Our assessment indicates that the majority of nesting turtles appear to be at low risk, but population management units in Western Australia and Queensland are vulnerable to light pollution. The risk to turtles from light generated by industrial developments appears significantly higher than at any other location. Consequently, managers of turtle management units in regions of proposed or on-going industrial development should anticipate potentially disrupted turtle behaviour due to light pollution. Our methodology will be useful to managers of turtles elsewhere.
EXTERNAL LINK
|
|
| 2002 |
Post-emergence handling of green turtle hatchlings: improving hatchery management worldwide |
van de Merwe JP, Ibrahim K, Whittier JM |
2012 |
N/A
|
|
|
KEYWORDS: hatchling quality, hatchling condition, running speed, artificial lighting, sea-finding ability, Malaysia |
|
ABSTRACT: Hatcheries are commonly used to protect sea turtle eggs from poaching and predation, however, there is currently limited scientific evidence to support good hatchery management practices, particularly post-hatching. This study investigated the effects of retaining hatchlings in hatcheries after emergence and delaying nest excavations on the quality of green turtle Chelonia mydas hatchlings. In addition, the effect of artificial lighting on the sea-finding ability of green turtles was investigated to highlight the importance of hatchling release locations on hatchery beaches. Hatchling running speed, an indicator of vigour and predation exposure, progressively decreased when hatchlings were retained in the hatchery for 1, 3 and 6 hours following emergence. Similarly, body condition (mass?:?straight carapace length), an indicator of dehydration and/or energy consumption, decreased after being retained for 3 and 6 hours. It was estimated that hatchlings retained for 6 hours after emergence would become significantly dehydrated and double their exposure to beach slope predation. Residual hatchlings that were immediately excavated from emerged nests had similar running speed and body condition to naturally emerged siblings. However, residual hatchlings removed from nests 5 days later had significantly reduced running speed and body condition, resulting in estimates of double the exposure to predation in near-shore areas. The mean angle of hatchling dispersal varied at different sites along the Ma’Daerah beach in relation to proximity to artificial lighting. Important recommendations for post-hatching management of sea turtle hatcheries worldwide can be made from the results of this study. To maximize release of hatchlings in the best condition as is possible, hatchlings should be released immediately after emergence, including excavation of any residual hatchlings. In addition, the dispersal angles of hatchlings should be tested at each hatchery beach to determine suitable release sites for efficient dispersal.
EXTERNAL LINK
|
|
| 2004 |
Assessing Marine World Heritage from an Ecosystem Perspective: The Western Indian Ocean. |
Obura DO, Church JE, Gabrié C |
2012 |
4.3 MB |
|
|
KEYWORDS: World Heritage, ecosystem, assessment |
|
EXTERNAL LINK
|
|
| 2005 |
Status and community-based conservation of marine turtles in the northern Querimbas Islands (Mozambique) |
Garnier J, Hill N, Guissamulo A, Silva I, Witt M, Godley B |
2012 |
N/A
|
|
|
KEYWORDS: Community-based conservation, green turtle, hawksbill turtle, migratory routes, Mozambique, population dynamics, satellite tracking |
|
ABSTRACT: Situated in the northernmost part of Mozambique, the northern Querimbas Islands support some of the most diverse and pristine coral reefs in the Western Indian Ocean. The community-based turtle conservation programme that we developed on Vamizi Island has facilitated the identification and protection of a key nesting site for the green marine turtle Chelonia mydas in Mozambique, with a mean of 122 nests per year. The area is also used by nesting female and immature hawksbill turtles Eretmochelys imbricata. Nesting activity of green turtles was observed all year round, with a peak in the summer (February–March). Incubation periods of this species showed seasonal fluctuations inversely correlated with air temperature. Hatching success was high (87%) when nests were not lost through tidal overwash and erosion, which affected nearly 40% of all nests in 2007. Using satellite tracking of four green turtles nesting on Vamizi we identified foraging grounds in marine protected areas in Kenya, Tanzania and north-west Madagascar. Migratory routes of two individuals along the East African coast were generally neritic and all passed through the waters of multiple nations and as many as six marine conservation areas, emphasizing the importance of regional cooperation. Awareness programmes were also conducted with resource users, and the development of a community-based management system triggered the creation of a marine sanctuary by the local community.
EXTERNAL LINK
|
|
| 2008 |
Global analysis of satellite tracking data shows that adult green turtles are signi?cantly aggregated in Marine Protected Areas |
Scott R, Hodgson DJ, Witt MJ, Coyne MS, Adnyana W, Blumenthal JM, Broderick AC, Canbolat AF, Catry P, Ciccione S, Delcroix E, Hitipeuw C, Luschi P, Pet-Soede L, Pendoley K, Richardson PB, Rees AF, Godley BJ |
2012 |
329 KB |
|
|
KEYWORDS: Chelonia mydas, foraging, marine megavertebrate, Marine Protected Area,
satellite tracking, sea turtle |
|
ABSTRACT: Aim Tracking technologies are often proposed as a method to elucidate the complex migratory life histories of migratory marine vertebrates, allowing spatially explicit threats to be identified and mitigated. We conducted a global analysis of foraging areas of adult green turtles (Chelonia mydas) subject to satellite tracking (n= 145) and the conservation designation of these areas according to International Union for Conservation of Nature criteria.
Location The green turtle has a largely circumtropical distribution, with adults migrating up to thousands of kilometres between nesting beaches and foraging areas, typically in neritic seagrass or algal beds.
Methods We undertook an assessment of satellite tracking projects that followed the movements of green turtles in tropical and subtropical habitats. This approach was facilitated by the use of the Satellite Tracking and Analysis Tool (http://www.seaturtle.org) and the integration of publicly available data on Marine Protected Areas (MPAs).
Results We show that turtles aggregate in designated MPAs far more than would be expected by chance when considered globally (35% of all turtles were located within MPAs) or separately by ocean basin (Atlantic 67%, Indian 34%, Mediterranean 19%, Pacific 16%). Furthermore, we show that the size, level of protection and time of establishment of MPAs affects the likelihood of MPAs containing foraging turtles, highlighting the importance of large, well-established reserves.
Main conclusions Our findings constitute compelling evidence of the world-wide effectiveness of extant MPAs in circumscribing important foraging habitats for a marine megavertebrate.
EXTERNAL LINK
|
|
| 2011 |
To eat or not to eat? Debris selectivity by marine turtles. |
Schuyler Q, Hardesty BD, Wilcox C, Townsend K |
2012 |
N/A
|
|
|
KEYWORDS: |
|
ABSTRACT: Marine debris is a growing problem for wildlife, and has been documented to affect more than 267 species worldwide. We investigated the prevalence of marine debris ingestion in 115 sea turtles stranded in Queensland between 2006–2011, and assessed how the ingestion rates differ between species (Eretmochelys imbricata vs. Chelonia mydas) and by turtle size class (smaller oceanic feeders vs. larger benthic feeders). Concurrently, we conducted 25 beach surveys to estimate the composition of the debris present in the marine environment. Based on this proxy measurement of debris availability, we modeled turtles’ debris preferences (color and type) using a resource selection function, a method traditionally used for habitat and food selection. We found no significant difference in the overall probability of ingesting debris between the two species studied, both of which have similar life histories. Curved carapace length, however, was inversely correlated with the probability of ingesting debris, 54.5% of pelagic sized turtles had ingested debris, whereas only 25% of benthic feeding turtles were found with debris in their gastrointestinal system. Benthic and pelagic sized turtles also exhibited different selectivity ratios for debris ingestion. Benthic phase turtles had a strong selectivity for soft, clear plastic, lending support to the hypothesis that sea turtles ingest debris because it resembles natural prey items such as jellyfish. Pelagic turtles were much less selective in their feeding, though they showed a trend towards selectivity for rubber items such as balloons. Most ingested items were plastic and were positively buoyant. This study highlights the need to address increasing amounts of plastic in the marine environment, and provides evidence for the disproportionate ingestion of balloons by marine turtles.
EXTERNAL LINK
|
|
| 2012 |
The role of turtles as coral reef macroherbivores. |
Goatley CHR, Hoey AS, Bellwood DR |
2012 |
N/A
|
|
|
KEYWORDS: |
|
ABSTRACT: Herbivory is widely accepted as a vital function on coral reefs. To date, the majority of studies examining herbivory in coral reef environments have focused on the roles of fishes and/or urchins, with relatively few studies considering the potential role of macroherbivores in reef processes. Here, we introduce evidence that highlights the potential role of marine turtles as herbivores on coral reefs. While conducting experimental habitat manipulations to assess the roles of herbivorous reef fishes we observed green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) showing responses that were remarkably similar to those of herbivorous fishes. Reducing the sediment load of the epilithic algal matrix on a coral reef resulted in a forty-fold increase in grazing by green turtles. Hawksbill turtles were also observed to browse transplanted thalli of the macroalga Sargassum swartzii in a coral reef environment. These responses not only show strong parallels to herbivorous reef fishes, but also highlight that marine turtles actively, and intentionally, remove algae from coral reefs. When considering the size and potential historical abundance of marine turtles we suggest that these potentially valuable herbivores may have been lost from many coral reefs before their true importance was understood.
EXTERNAL LINK
|
|
| 2013 |
Conservation related insights into the behaviour of the olive ridley sea turtle Lepidochelys olivacea nesting in Oman. |
Rees AF, Al-Kiyumi A, Broderick AC, Papathanasopoulou N, Godley BJ |
2012 |
644 KB |
|
|
KEYWORDS: Lepidochelys olivacea, Satellite tracking, Migration, Behavioural plasticity, Nesting, Indian Ocean |
|
ABSTRACT: We followed the movements of 9 adult female olive ridley turtles Lepidochelys olivacea after nesting on Masirah Island, Oman, using satellite tracking. Their post-breeding migrations ranged from 85 to 796 km. Three individuals travelled north to foraging grounds in Pakistan, Iran and the United Arab Emirates. The other 6 turtles remained in Omani seas for extended periods (mean ± SD = 171.3 ± 109.4 d, range = 40 to 310 d). These locally resident turtles experienced biannual cooling of sea temperatures due to the effect of the west Arabian Sea upwelling which was not experienced by those that migrated to the north. Indications of disparity in turtle size between foraging locations are identified for the first time in this species. The majority of turtles (8) settled in coastal areas of water depth <100 m. Two locally resident turtles remained in very shallow water (<40 m depth) where they were capable of extended dive durations (>100 min) in water warmer than 21°C, which is a feature unique to olive ridleys amongst sea turtles. They displayed a shift to shorter diving after breeding, indicating increased activity levels. The entire spatial footprint of olive ridley dispersal remained within a putative regional management unit (RMU) for this species in the western Indian Ocean, supporting its delineation. We reveal Oman’s key role in conserving this demographic unit, with 6 turtles remaining within its national boundary. Our data add to the growing body of evidence that marine turtles show varied migration behaviours within populations, thus complicating their management.
EXTERNAL LINK
|
|
| 1644 |
Abstract of the 7th International Symposium on SEASTAR2000 and Asian Bio-logging Science (The 11th SEASTAR2000 Workshop) |
Anonymous |
2011 |
11.3 MB |
|
|
KEYWORDS: |
|
EXTERNAL LINK
|
|
| 1917 |
Conservation of Green Turtle (Chelonia mydas) at Daran Beach, Jiwani, Balochistan |
Waqas U, Hasnain S, Ahmad E, Abbasi M, Pandrani A |
2011 |
177 KB |
|
|
KEYWORDS: Marine turtle, endangered species, Makran coast, North Arabian Sea, turtle conservation |
|
ABSTRACT: The green turtle (Chelonia mydas) is a large marine turtle belonging to the family Cheloniidae, class Reptilia. ‘Sandy beach’ of Jiwani is one of the most important nesting beaches for the green turtle in Pakistan. WWF – Pakistan monitored the green turtle population along the Jiwani coast between 1999 and 2008. A total of 2, 731 nests were protected, from which 91, 936 hatchlings emerged out and were released into the sea. This paper gives the details on the annual nesting population and emerging hatchlings. |
|
| 1935 |
Impact des macrodéchets sur les tortues marines en France métropolitaine et d’Outre-mer. |
Claro F, Hubert P |
2011 |
N/A
|
|
|
KEYWORDS: |
|
EXTERNAL LINK
|
|
| 1936 |
Les tortues marines et la pollution lumineuse sur le territoire française. |
Claro F, Bardonnet C |
2011 |
N/A
|
|
|
KEYWORDS: |
|
EXTERNAL LINK
|
|
| 1937 |
Monitoring Nesting Trends and Hatchling Success of the Green Turtle (Chelonia mydas) Population on Mnemba Island, Zanzibar |
Dunbar T |
2011 |
535 KB |
|
|
KEYWORDS: Monitoring, nesting trend, hatchling success, green, Chelonia mydas, population, Zanzibar |
|
ABSTRACT: The nesting trends and hatching success of Green sea turtles (Chelonia mydas) were studied on Mnemba Island. This study involved a continuation of data collection for the ongoing monitoring program of sea turtles on Mnemba Island. Data was collected from nesting females as well as from post hatching nest excavations. The data that has been collected over the course of ten years was then analyzed to examine trends over time as well as to assess the current status of the turtle population on Mnemba Island. Hatch success as a function of different seasons was analyzed. It has been concluded that there is a significant difference between hatching success in wet and dry seasons, but not in the different monsoon seasons. Hatch success as a function of location on the island was also explored, and trends in frequencies of nest sites in various locations were examined. Trends in nest location selection were investigated in relation to coastal erosion occurrences. The only significant preferences for nest location found was that the majority of nest sites were concentrated on the western and southwestern sides of the island. This is also related to trends in nest site selection in relation to coastal erosion, as there are no occurrences of nests on eastern side of the island, which experiences the most erosion. Furthermore, it has also been concluded that there is no difference in hatching success between years, and that hatching success has not significantly changed over time. This implies that Mnemba Island provides a stable environment for nesting green turtles, and is therefore an important area to continue to conserve. Recommendations for future studies are made.
EXTERNAL LINK
|
|
| 2009 |
Large-scale movement patterns of male loggerhead sea turtles (caretta caretta) in Shark Bay, Australia. |
Olson E |
2011 |
696 KB |
|
|
KEYWORDS: loggerhead turtle, satellite telemetry, traditional ecological knowledge, local
ecological knowledge, Shark Bay |
|
ABSTRACT: The Shark Bay World Heritage Property is home to the largest breeding population of loggerhead turtles in Australia. With little known about the movements of males in this population, I assessed the large-scale movement and habitat use patterns of adult male loggerhead turtles to inform conservation strategies. I tagged nine male loggerhead turtles with SPOT satellite tags and tracked them for seven months. Turtles exhibited fidelity to foraging areas considerably smaller than anticipated, with activity space sizes (85 pvc) that were on average 186.0 km2 (± 206.0 sd). To complement tracking data, I interviewed eight Aboriginal fishermen and local ecotourism operators and recorded their traditional and local ecological knowledge concerning loggerhead turtle movements and habitat use. Respondents suggested loggerheads stay within small areas and that there are some areas in the bay where loggerheads are more abundant. Traditional and local ecological knowledge therefore corroborated quantitative satellite tracking data.
EXTERNAL LINK
|
|
| 2015 |
Long-Term Climate Forcing in Loggerhead Sea Turtle Nesting |
Van Houtan, K. S., Halley, J. M. |
2011 |
N/A
|
|
|
KEYWORDS: Loggerhead (Caretta caretta, Population, Predictive Modelling, Climate, Oceanographic Processes, Great Barrier Reef, Nesting. |
|
ABSTRACT: The long-term variability of marine turtle populations remains poorly understood, limiting science and management. Here we use basin-scale climate indices and regional surface temperatures to estimate loggerhead sea turtle (Caretta caretta) nesting at a variety of spatial and temporal scales. Borrowing from fisheries research, our models investigate how oceanographic processes influence juvenile recruitment and regulate population dynamics. This novel approach finds local populations in the North Pacific and Northwest Atlantic are regionally synchronized and strongly correlated to ocean conditions—such that climate models alone explain up to 88% of the observed changes over the past several decades. In addition to its performance, climate-based modeling also provides mechanistic forecasts of historical and future population changes. Hindcasts in both regions indicate climatic conditions may have been a factor in recent declines, but future forecasts are mixed. Available climatic data suggests the Pacific population will be significantly reduced by 2040, but indicates the Atlantic population may increase substantially. These results do not exonerate anthropogenic impacts, but highlight the significance of bottom-up oceanographic processes to marine organisms. Future studies should consider environmental baselines in assessments of marine turtle population variability and persistence.
EXTERNAL LINK
|
|
| 2017 |
Management strategies to mitigate the impacts of climate change on sea turtle's terrestrial reproductive phase |
Fuentes, M.M.P.B., Fish, M.R., and Maynard, J.A. |
2011 |
N/A
|
|
|
KEYWORDS: Adaptive management, Climate change, Conservation, Sea turtles, Management strategies |
|
ABSTRACT: Climate change poses a serious threat to sea turtles (Cheloniidae) as their terrestrial reproductive phase is only successful within a limited range of environmental and physical conditions. These conditions are likely to become less optimal as climate change progresses. To date, management and conservation of sea turtles has focused almost entirely on non-climatic stressors, due at least in part to practitioners not knowing what strategies to take and the feasibility and risks of potential strategies. To aid the management of sea turtles in a changing environment, we identified management strategies via a focus workshop and surveys to mitigate the impacts of climate change to the terrestrial reproductive phase of sea turtles. The effectiveness, ecological risks and potential social and logistical constraints associated with implementing each of the identified management strategies is discussed. Twenty management strategies were identified, strategies varied from habitat protection to more active and direct manipulation of nests and the nesting environment. Based on our results, we suggest a three-pronged approach to sea turtle conservation in light of climate change, where managers and researchers should: 1) enhance sea turtle resilience to climate change by mitigating other threats, 2) prioritise implementing the 'no regret' and 'reversible' management strategies identified here, and 3) fill the knowledge gaps identified to aid the trial and implementation of the potential strategies identified here. By combining these three approaches our collective toolkit of sea turtle management strategies will expand, giving us an array of viable approaches to implement as climate change impacts become more extreme.
EXTERNAL LINK
|
|
| 2019 |
Relationship between tropical cyclones and the distribution of sea turtle nesting grounds |
Fuentes, M. M. P. B., Bateman, B. L. , Hamann, M. |
2011 |
N/A
|
|
|
KEYWORDS: Conservation management, Disturbance, Evolutionary selection, Nesting sites, Queensland, Sea turtles, Species distribution, Tropical cyclones |
|
ABSTRACT: Aim: This study examines the relationship between the distribution of existing sea turtle nesting sites and historical patterns of tropical cyclone events to investigate whether cyclones influence the current distribution of sea turtle nesting sites. The results, together with information on predicted cyclone activity and other key environmental variables, will help in the identification and prediction of future nesting sites for sea turtles as changes to the coastal environment continue.
Location: Queensland, Australia.
Methods: We used data on the nesting distribution of seven populations of four species of sea turtles [green (Chelonia mydas), flatback (Natator depressus), hawksbill (Eretmochelys imbricata) and loggerhead (Caretta caretta)] from the eastern Queensland coast, and tropical cyclone track data from 1969 to 2007 to explore the relationship between (1) sea turtle nesting phenology and cyclone season, and (2) sea turtle nesting sites and cyclone distribution. Furthermore, using two green turtle populations as a case study, we investigated the relationship between cyclone disturbance and sea turtle reproductive output, nesting site and season. Bootstrapping was used to explore if current sea turtle nesting sites are located in areas with lower or higher cyclone frequency than areas where turtles are currently not nesting.
Results: All populations of sea turtles studied here were disturbed by cyclone activity during the study period. The exposure (frequency) of tropical cyclones that crossed each nesting site varied greatly among and within the various sea turtle populations. This was mainly a result of the spatial distribution of each population’s nesting sites. Bootstrapping indicated that nesting sites generally have experienced lower cyclone activity than other areas that are available for nesting.
Main conclusions: Tropical cyclones might have been sufficiently detrimental to sea turtle hatching success on the eastern Queensland coast that through a natural selection process turtles in this region are now nesting in areas with lower cyclone activity. Therefore, it is important that future studies that predict climate or range shifts for sea turtle nesting distributions consider future cyclone activity as one of the variables in their model.
EXTERNAL LINK
|
|
|
Print search results