Marine turtle nest depredation by feral pigs (Sus scrofa) on the Western Cape York Peninsula, Australia: implications for management

Context The west coast of the Cape York Peninsula (CYP) is a major nesting ground for three species of threatened marine turtle, namely, the flatback (Natator depressus), olive ridley (Lepidochelys olivacea) and hawksbill (Eretemochelys imbricata). Marine turtle nests in this area experience high rates of depredation and unpublished data from numerous studies have suggested that feral pigs are responsible for most nest losses. Aims The aim of the present study was to identify the relative magnitude of nest mortality associated with physical processes versus depredation and to distinguishing between two possible pig depredation scenarios. Methods We documented laying and mortality patterns on Pennefarther Beach (CYP) over a 49-day period in 2007. We partitioned mortality into components attributable to beach erosion, inundation and depredation and also assessed the relative magnitude of depredation associated with different nest predators. We used these data to test whether the temporal and spatial pattern of pig depredation was random with respect to patterns of nest availability. Key results The overall level of nest mortality was 40.2%. Depredation was responsible for 93% of nest losses. Pig predation was high, accounting for 89.6% of all mortality. Depredation occurred equally across nests of all three turtle species. Although nests were laid uniformly in both time and space, pig depredation was significantly clustered. Conclusions Depredation by feral pigs was the principal cause of turtle nest mortality in the present study. The pattern of nest destruction was consistent with the occurrence of pig depredation by single individuals in discrete feeding areas. Implications Current feral pig management involves aerial shooting. This is effective at removing large numbers of animals over large areas. However, aerial shooting is also expensive. Our results suggest that targeted monitoring and eradication of locally active individuals depredating nests may better manage pig impacts, specifically those on turtle nests.

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The Olive Ridley Project (ORP): A successful example of how to engage researchers, conservation practitioners and civil society

Research for All ◽

10.14324/rfa.05.2.17 ◽

2021 ◽

Vol 5 (2) ◽

Author(s):

Martin Stelfox ◽

Mercedes Martin-Cereceda ◽

Karim Vahed ◽

Jillian Hudgins ◽

Stephanie Köhnk ◽

...

Keyword(s):

Spatial Ecology ◽

Community Education ◽

Knowledge Exchange ◽

Sustainable Use ◽

Sea Turtle ◽

Marine Turtle ◽

Olive Ridley ◽

Turtle Species ◽

Research Engagement ◽

The Uk

The Olive Ridley Project (ORP) was set up to protect sea turtles and their habitats. The project was formed in 2013, and it became a registered charity in the UK in 2016. From its inception, ORP took a multidisciplinary approach to achieve its goals. Part of its objectives, and the reason why the charity came to fruition, are related to the issue of olive ridley sea turtle (Lepidochelys olivacea) entanglement in abandoned, lost or discarded fishing gear (also known as ‘ghost gear’ or ‘ghost nets’), and the search for ghost gear and turtle entanglement ‘hot spots’ throughout the Indian Ocean. The initial ORP research questions were soon challenged by societal interests to develop inclusive educational programmes in local communities and tourist resorts that could raise awareness about the need for conservation of all sea turtle species. In February 2017, ORP opened the first veterinarian-run, fully equipped Marine Turtle Rescue Centre in the Maldives, bringing together the work of researchers, citizen scientists, volunteers, environmentalists, marine biologists and veterinarians. The present work of ORP sits on a strong and scientifically robust collaborative plan. Current ORP research projects range from sea turtle population analyses, spatial ecology, rehabilitation of injured and sick individuals, epibiont parasite analyses, precise turtle identification through photo-ID research, linking ghost gear to responsible fisheries, and analyses of ghost gear drift patterns. The programme enhances community education and outreach by engaging schoolchildren, organizing workshops, promoting sustainable use of ghost gear waste, and training citizen scientists and local fishing communities. The ORP programme encompasses many principles of research engagement, effectively combining scientific knowledge, education and action. This article explores all stages of the process (from research planning and design, to knowledge exchange and inter- and trans-disciplinary impact assessments), describing the active engagement originated by the ORP initiative. A reflective insight into the learning, enrichment and challenges of engaging researchers and community actors is also included, considering the current social and scientific framework.

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The nesting success of green turtles on beaches at Kazanli, Turkey

Oryx ◽

10.1017/s0030605300023607 ◽

1992 ◽

Vol 26 (3) ◽

pp. 165-171 ◽

Cited By ~ 1

Author(s):

Stephanie J. Coley ◽

Andrew C. Smart

Keyword(s):

Nest Site ◽

Chelonia Mydas ◽

Nesting Success ◽

Beach Erosion ◽

Marine Turtle ◽

Chemical Pollution ◽

Turtle Species ◽

Green Turtles ◽

Nesting Beaches ◽

Turkish Society

The green turtle Chelonia mydas is one of two marine turtle species to nest in Turkey. Its three main nesting beaches are in eastern Turkey, with possibly the densest congregation of nesting turtles in the Mediterranean being found at Kazanli. However, beach erosion, hatchling predation, agricultural encroachment and chemical pollution mean that the future of the Kazanli nest site is uncertain. The Turkish Society for the Protection of Nature (Dogal Hayati Koruma Dernegi) is making valiant efforts to protect all the turtle nesting beaches in Turkey but lacks detailed information on the numbers of nesting turtles on many beaches. This paper describes a short study of nesting turtles at Kazanli during 1990 and makes recommendations for the conservation of the nesting beach.

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An evaluation of nest predator impacts and the efficacy of plastic meshing on marine turtle nests on the western Cape York Peninsula, Australia

Biological Conservation ◽

10.1016/j.biocon.2019.108201 ◽

2019 ◽

Vol 238 ◽

pp. 108201 ◽

Cited By ~ 3

Author(s):

Eric J. Nordberg ◽

Stewart Macdonald ◽

Gina Zimny ◽

Andrew Hoskins ◽

Anders Zimny ◽

...

Keyword(s):

Marine Turtle ◽

Western Cape ◽

Cape York ◽

Nest Predator

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Inferred Adult Foraging Grounds of Two Marine Turtle Species Nesting at Amami-Oshima, Japan

Chelonian Conservation and Biology ◽

10.2744/ccb-1337.1 ◽

2019 ◽

Vol 18 (1) ◽

pp. 91

Author(s):

Katsuki Oki ◽

Tomoko Hamabata ◽

Toshimitsu Arata ◽

Denise M. Parker ◽

Connie Ka Yan Ng ◽

...

Keyword(s):

Marine Turtle ◽

Turtle Species

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Dietary analysis of two sympatric marine turtle species in the eastern Mediterranean

Marine Biology ◽

10.1007/s00227-021-03895-y ◽

2021 ◽

Vol 168 (6) ◽

Author(s):

Josie L. Palmer ◽

Damla Beton ◽

Burak A. Çiçek ◽

Sophie Davey ◽

Emily M. Duncan ◽

...

Keyword(s):

Green Turtle ◽

Eastern Mediterranean ◽

Chelonia Mydas ◽

Marine Turtle ◽

Dietary Analysis ◽

Low Frequencies ◽

Turtle Species ◽

Dietary Shift ◽

Green Turtles ◽

Loggerhead Turtles

AbstractDietary studies provide key insights into threats and changes within ecosystems and subsequent impacts on focal species. Diet is particularly challenging to study within marine environments and therefore is often poorly understood. Here, we examined the diet of stranded and bycaught loggerhead (Caretta caretta) and green turtles (Chelonia mydas) in North Cyprus (35.33° N, 33.47° E) between 2011 and 2019. A total of 129 taxa were recorded in the diet of loggerhead turtles (n = 45), which were predominantly carnivorous (on average 72.1% of dietary biomass), foraging on a large variety of invertebrates, macroalgae, seagrasses and bony fish in low frequencies. Despite this opportunistic foraging strategy, one species was particularly dominant, the sponge Chondrosia reniformis (21.5%). Consumption of this sponge decreased with increasing turtle size. A greater degree of herbivory was found in green turtles (n = 40) which predominantly consumed seagrasses and macroalgae (88.8%) with a total of 101 taxa recorded. The most dominant species was a Lessepsian invasive seagrass, Halophila stipulacea (31.1%). This is the highest percentage recorded for this species in green turtle diet in the Mediterranean thus far. With increasing turtle size, the percentage of seagrass consumed increased with a concomitant decrease in macroalgae. Seagrass was consumed year-round. Omnivory occurred in all green turtle size classes but reduced in larger turtles (> 75 cm CCL) suggesting a slow ontogenetic dietary shift. Macroplastic ingestion was more common in green (31.6% of individuals) than loggerhead turtles (5.7%). This study provides the most complete dietary list for marine turtles in the eastern Mediterranean.

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Critical In-Water Habitats for Post-Nesting Sea Turtles from the Southern Gulf of Mexico

Journal of Marine Science and Engineering ◽

10.3390/jmse9080793 ◽

2021 ◽

Vol 9 (8) ◽

pp. 793

Author(s):

Abigail Uribe-Martínez ◽

María de los Angeles Liceaga-Correa ◽

Eduardo Cuevas

Keyword(s):

Gulf Of Mexico ◽

Marine Ecosystem ◽

Satellite Telemetry ◽

Marine Turtle ◽

Home Ranges ◽

The Bahamas ◽

Turtle Species ◽

Southern Gulf Of Mexico ◽

Large Marine Ecosystem ◽

Physical Features

Marine turtles are globally endangered species that spend more than 95% of their life cycle in in-water habitats. Nevertheless, most of the conservation, recovery and research efforts have targeted the on-land habitats, due to their easier access, where adult females lay their eggs. Targeting the large knowledge gaps on the in-water critical habitats of turtles, particularly in the Large Marine Ecosystem Gulf of Mexico, is crucial for their conservation and recovery in the long term. We used satellite telemetry to track 85 nesting females from their beaches after they nested to identify their feeding and residency habitats, their migratory corridors and to describe the context for those areas. We delimited major migratory corridors in the southern Gulf of Mexico and West Caribbean and described physical features of internesting and feeding home ranges located mainly around the Yucatan Peninsula and Veracruz, Mexico. We also contributed by describing general aggregation and movement patterns for the four marine turtle species in the Atlantic, expanding the knowledge of the studied species. Several tracked individuals emigrated from the Gulf of Mexico to as far as Nicaragua, Honduras, and the Bahamas. This information is critical for identifying gaps in marine protection and for deciphering the spatial connectivity in large ocean basins, and it provides an opportunity to assess potential impacts on marine turtle populations and their habitats.

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Plastic ingestion by freshwater turtles: a review and call to action

Scientific Reports ◽

10.1038/s41598-021-84846-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Adam G. Clause ◽

Aaron J. Celestian ◽

Gregory B. Pauly

Keyword(s):

Marine Species ◽

Marine Turtle ◽

Freshwater Turtle ◽

Freshwater Turtles ◽

Plastic Pollution ◽

Potential Threat ◽

Implementation Quality ◽

Turtle Species ◽

Marine Turtles ◽

Conservation Concern

AbstractPlastic pollution, and especially plastic ingestion by animals, is a serious global issue. This problem is well documented in marine systems, but it is relatively understudied in freshwater systems. For turtles, it is unknown how plastic ingestion compares between marine and non-marine species. We review the relevant turtle dietary literature, and find that plastic ingestion is reported for all 7 marine turtle species, but only 5 of 352 non-marine turtle species. In the last 10 years, despite marine turtles representing just 2% of all turtle species, almost 50% of relevant turtle dietary studies involved only marine turtles. These results suggest that the potential threat of plastic ingestion is poorly studied in non-marine turtles. We also examine plastic ingestion frequency in a freshwater turtle population, finding that 7.7% of 65 turtles had ingested plastic. However, plastic-resembling organic material would have inflated our frequency results up to 40% higher were it not for verification using Raman spectroscopy. Additionally, we showcase how non-native turtles can be used as a proxy for understanding the potential for plastic ingestion by co-occurring native turtles of conservation concern. We conclude with recommendations for how scientists studying non-marine turtles can improve the implementation, quality, and discoverability of plastic ingestion research.

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Natal foraging philopatry in eastern Pacific hawksbill turtles

Royal Society Open Science ◽

10.1098/rsos.170153 ◽

2017 ◽

Vol 4 (8) ◽

pp. 170153 ◽

Cited By ~ 6

Author(s):

Alexander R. Gaos ◽

Rebecca L. Lewison ◽

Michael P. Jensen ◽

Michael J. Liles ◽

Ana Henriquez ◽

...

Keyword(s):

Genetic Research ◽

Eastern Pacific ◽

Marine Turtle ◽

Natal Philopatry ◽

Eretmochelys Imbricata ◽

Turtle Species ◽

Marine Turtles ◽

Complex Processes ◽

Natal Homing ◽

Hawksbill Turtles

The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles ( Eretmochelys imbricata ) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

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Does behaviour affect the dispersal of flatback post-hatchlings in the Great Barrier Reef?

Royal Society Open Science ◽

10.1098/rsos.170164 ◽

2017 ◽

Vol 4 (5) ◽

pp. 170164 ◽

Cited By ~ 8

Author(s):

Natalie Wildermann ◽

Kay Critchell ◽

Mariana M. P. B. Fuentes ◽

Colin J. Limpus ◽

Eric Wolanski ◽

...

Keyword(s):

Great Barrier Reef ◽

Early Life ◽

Marine Turtle ◽

Life Stages ◽

Barrier Reef ◽

Early Life Stages ◽

Turtle Species ◽

Local Water ◽

Natator Depressus ◽

Nesting Beaches

The ability of individuals to actively control their movements, especially during the early life stages, can significantly influence the distribution of their population. Most marine turtle species develop oceanic foraging habitats during different life stages. However, flatback turtles ( Natator depressus ) are endemic to Australia and are the only marine turtle species with an exclusive neritic development. To explain the lack of oceanic dispersal of this species, we predicted the dispersal of post-hatchlings in the Great Barrier Reef (GBR), Australia, using oceanographic advection-dispersal models. We included directional swimming in our models and calibrated them against the observed distribution of post-hatchling and adult turtles. We simulated the dispersal of green and loggerhead turtles since they also breed in the same region. Our study suggests that the neritic distribution of flatback post-hatchlings is favoured by the inshore distribution of nesting beaches, the local water circulation and directional swimming during their early dispersal. This combination of factors is important because, under the conditions tested, if flatback post-hatchlings were entirely passively transported, they would be advected into oceanic habitats after 40 days. Our results reinforce the importance of oceanography and directional swimming in the early life stages and their influence on the distribution of a marine turtle species.

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