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18 pages, 3284 KiB

Open AccessArticle

Fishermen Interviews: A Cost-Effective Tool for Evaluating the Impact of Fisheries on Vulnerable Sea Turtles in Tunisia and Identifying Levers of Mitigation

by Maissa Louhichi, Alexandre Girard and Imed Jribi

Animals 2023, 13(9), 1535; https://doi.org/10.3390/ani13091535 - 04 May 2023

Viewed by 2711

Abstract

Fisheries bycatch is considered one of the main threats to sea turtles. To provide an updated assessment of the bycatch impact on loggerhead turtles in Tunisia, 483 interviews were conducted with fishermen in 19 ports along the Gulfs of Gabes and Hammamet. The [...] Read more.

Fisheries bycatch is considered one of the main threats to sea turtles. To provide an updated assessment of the bycatch impact on loggerhead turtles in Tunisia, 483 interviews were conducted with fishermen in 19 ports along the Gulfs of Gabes and Hammamet. The interview questions included data on vessel and fishing gear characteristics, monthly fishing effort, and monthly sea turtle bycatch of the last year. Results revealed that sea turtle bycatch per unit effort (BPUE) was the highest for ray nets (0.73 turtles/vessel/day, 95% CI [0.02–1.15]), followed by pelagic longlines (0.6 turtles/vessel/day, 95% CI [0–4.23]) and shark nets (0.4 turtles/vessel/day, 95% CI [0–2.12]). However, due to the trawlers’ high fishing effort, the cumulative impact of the trawl nets was the highest with an estimated number of 11,740 (95% CI [0–41,525.75]) turtles caught per year in Tunisia. Factors influencing the bycatch risk were gear characteristics (mesh size for nets, hook size for longlines, vertical opening for trawls), as well as season and location of operations. These factors will guide the research of mitigation solutions. The interviews with fishermen proved to be a cost-effective approach for the rapid assessment of sea turtle interactions with fisheries in the context of Tunisia. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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17 pages, 2300 KiB

Open AccessArticle

Natal Origin and Spatiotemporal Distribution of Leatherback Turtle (Dermochelys coriacea) Strandings at a Foraging Hotspot in Temperate Waters of the Southwest Atlantic Ocean

by Gabriela M. Vélez-Rubio, Laura Prosdocimi, Milagros López-Mendilaharsu, Maria Noel Caraccio, Alejandro Fallabrino, Erin L. LaCasella and Peter H. Dutton

Animals 2023, 13(8), 1285; https://doi.org/10.3390/ani13081285 - 08 Apr 2023

Viewed by 2318

Abstract

Leatherback turtles migrate long distances between nesting beaches and distant foraging areas worldwide. This study analyzes the genetic diversity, life history stage, spatiotemporal distribution, and associated threats of a foraging aggregation in the Southwest Atlantic Ocean. A total of 242 leatherbacks stranded or [...] Read more.

Leatherback turtles migrate long distances between nesting beaches and distant foraging areas worldwide. This study analyzes the genetic diversity, life history stage, spatiotemporal distribution, and associated threats of a foraging aggregation in the Southwest Atlantic Ocean. A total of 242 leatherbacks stranded or bycaught by artisanal fisheries were recorded from 1997 to 2021 in Uruguay, with sizes ranging from 110.0 to 170.0 cm carapace lengths, indicating that the aggregation is composed of large juveniles and adults. Results of Bayesian mixed-stock analysis show that leatherbacks come primarily from the West African rookeries, based on mitochondrial DNA sequences obtained from 59 of the turtles representing seven haplotypes, including a novel one (Dc1.7). The main threat identified in the area is the fisheries bycatch but most of the carcasses observed were badly decomposed. There was significant seasonal and interannual variability in strandings that is likely associated with the availability of prey and the intensity of the fishing effort. Taken together, these findings reinforce the importance of these South American foraging areas for leatherbacks and the need to determine regional habitat use and migratory routes across the broader Atlantic region, in order to develop effective conservation measures to mitigate threats both at nesting beaches and foraging areas. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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21 pages, 5465 KiB

Open AccessArticle

Satellite Tracking of Head-Started Juvenile Green Turtles (Chelonia mydas) Reveals Release Effects and an Ontogenetic Shift

by Nicole Barbour, Helen Bailey, William F. Fagan, Walter Mustin, Vandanaa Baboolal, Francesca Casella, Tony Candela, Philippe Gaspar, Sean Williamson, Emily Turla and George L. Shillinger

Animals 2023, 13(7), 1218; https://doi.org/10.3390/ani13071218 - 31 Mar 2023

Cited by 2 | Viewed by 2564

Abstract

Juveniles of marine species, such as sea turtles, are often understudied in movement ecology. To determine dispersal patterns and release effects, we released 40 satellite-tagged juvenile head-started green turtles (Chelonia mydas, 1–4 years) from two separate locations (January and July 2023) [...] Read more.

Juveniles of marine species, such as sea turtles, are often understudied in movement ecology. To determine dispersal patterns and release effects, we released 40 satellite-tagged juvenile head-started green turtles (Chelonia mydas, 1–4 years) from two separate locations (January and July 2023) off the coast of the Cayman Islands. A statistical model and vector plots were used to determine drivers of turtle directional swimming persistence and the role of ocean current direction. More than half (N = 22) effectively dispersed in 6–22 days from the islands to surrounding areas. The January turtles radiated out (185–1138 km) in distinct directions in contrast to the northward dispersal of the July turtles (27–396 km). Statistical results and vector plots supported that daily swimming persistence increased towards the end of tracks and near coastal regions, with turtles largely swimming in opposition to ocean currents. These results demonstrate that captive-reared juvenile greens have the ability to successfully navigate towards key coastal developmental habitats. Differences in dispersal (January vs. July) further support the importance of release timing and location. Our results inform conservation of the recovering Caymanian green turtles and we advise on how our methods can be improved and modified for future sea turtle and juvenile movement ecology studies. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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15 pages, 597 KiB

Open AccessArticle

Trace Elements and Persistent Organic Pollutants in Unhatched Loggerhead Turtle Eggs from an Emerging Nesting Site along the Southwestern Coasts of Italy, Western Mediterranean Sea

by Mauro Esposito, Silvia Canzanella, Doriana Iaccarino, Angela Pepe, Fabio Di Nocera, Teresa Bruno, Laura Marigliano, Donato Sansone, Sandra Hochscheid, Pasquale Gallo and Fulvio Maffucci

Animals 2023, 13(6), 1075; https://doi.org/10.3390/ani13061075 - 16 Mar 2023

Cited by 5 | Viewed by 1902

Abstract

Marine pollution is one of the major threats affecting loggerhead turtles, which due to their long life span, highly migratory behavior, and carnivorous diet, may be exposed to elevated levels of toxic elements throughout their life. The transfer of chemicals from mothers to [...] Read more.

Marine pollution is one of the major threats affecting loggerhead turtles, which due to their long life span, highly migratory behavior, and carnivorous diet, may be exposed to elevated levels of toxic elements throughout their life. The transfer of chemicals from mothers to their offspring is of particular conservation concern because it may affect embryonic development and hatching success. In this study, the concentrations of 16 toxic and potentially toxic trace elements, 6 indicator polychlorinated biphenyls (PCBs), and organochlorine pesticide residues (OCPs) were determined in 138 eggs from 46 loggerhead turtle nests laid during the 2021 nesting season in Campania, Italy, western Mediterranean Sea. The possible impact of pollutant levels on hatching success and early embryonic death was also investigated. Trace element analysis was performed using an ICP-MS, except for mercury, which was determined using a Direct Mercury Analyzer® (DMA). PCBs and OCPs were analyzed with high-resolution gas chromatography coupled with high-resolution mass spectrometry (HRGC-HRMS) and gas chromatography tandem quadrupole mass spectrometry GC-MS /MS, respectively. The concentrations of essential elements in the eggs were higher than those of non-essential elements. In addition, the highly chlorinated PCBs (153, 138, and 180) contributed the most to the total PCBs, while OCPs were not detected. No correlations were found between contaminant concentrations and reproductive parameters (hatching success and no obvious embryos). The results obtained suggest that the levels of contaminants found in the eggs do not affect the reproductive success of the species in the study area. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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13 pages, 4197 KiB

Open AccessArticle

Predation Rate on Olive Riley Sea Turtle (Lepidochelys olivacea) Nests with Solitary Nesting Activity from 2008 to 2021 at Corozalito, Costa Rica

by Nínive Espinoza-Rodríguez, Daniela Rojas-Cañizales, Carmen Mejías-Balsalobre, Isabel Naranjo and Randall Arauz

Animals 2023, 13(5), 875; https://doi.org/10.3390/ani13050875 - 28 Feb 2023

Cited by 2 | Viewed by 1121

Abstract

In Corozalito beach, Costa Rica, Olive Ridley turtles (Lepidochelys olivacea) nest both solitarily and in arribadas. The predation of solitary nests was monitored from 2008 to 2021, recording date, time, sector of the beach, zone, status of nest (predated or partially [...] Read more.

In Corozalito beach, Costa Rica, Olive Ridley turtles (Lepidochelys olivacea) nest both solitarily and in arribadas. The predation of solitary nests was monitored from 2008 to 2021, recording date, time, sector of the beach, zone, status of nest (predated or partially predated) and predator when possible. We recorded 4450 predated nests in total (N = 30,148 nesting events); predation rates showed a fluctuating trend, with recent percentages reaching up to 30%, with four distinctive dips in 2010, 2014, 2016 and 2017. The spatial distribution of predated nests along the beach showed significant differences among the sectors regardless of the seasons (Friedman test, chi-squared = 14.778, df = 2, p-value = 0.000), with most predated nests (47.62%) occurring in the northern sectors of the beach. Predators were identified by their tracks and/or direct observations (N = 896, 24.08%). The most conspicuous predators identified were raccoons (55.69%) and black vultures (22.77%). As seen in Corozalito, predation rates have increased in recent years despite established conservation efforts. A comprehensive assessment of all threats towards the overall hatching success for clutches is needed, considering predation during mass nesting events, poaching and beach erosion, among other factors, to fully understand the nesting dynamics occurring in this beach. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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13 pages, 2995 KiB

Open AccessArticle

Environmental and Nesting Variables Associated with Atlantic Leatherback Sea Turtle (Dermochelys coriacea) Embryonic and Hatching Success Rates in Grenada, West Indies

by Kate E. Charles, Clare E. Morrall, Jonnel J. Edwards, Kenrith D. Carter, Josephine A. Afema, Brian P. Butler and David P. Marancik

Animals 2023, 13(4), 685; https://doi.org/10.3390/ani13040685 - 16 Feb 2023

Cited by 1 | Viewed by 2228

Abstract

Annual monitoring of leatherback sea turtle (Dermochelys coriacea) nesting grounds in Grenada, West Indies has identified relatively low hatch rates compared to worldwide trends. This study investigated the impact of selected environmental variables on leatherback sea turtle embryonic development and hatching [...] Read more.

Annual monitoring of leatherback sea turtle (Dermochelys coriacea) nesting grounds in Grenada, West Indies has identified relatively low hatch rates compared to worldwide trends. This study investigated the impact of selected environmental variables on leatherback sea turtle embryonic development and hatching success rates on Levera Beach in Grenada between 2015–2019. The mean number of nests per year and eggs per nest were 667.6 ± 361.6 and 80.7 ± 23.0 sd, respectively. Within excavated nests, 35.6% ± 22.0 sd of eggs successfully developed embryos and 30.6% ± 22.6 sd of eggs successfully hatched. The number of eggs per nest, along with embryo and hatching success rates, differed by nesting year. Embryo development success rate was associated with nest location, and both embryo development and hatching success rates were positively associated with nest depth and negatively associated with the percentage of eggs exhibiting microbial growth and with the presence of inspissated yolk. There was no embryo development or hatchling success association with month of the nesting season, distance from the high-water mark, distance from vegetation, nor maternal carapace length. The mean nest temperature was 31.7 °C ± 1.64 sd and mean temperatures during the middle third of egg incubation suggest clutches are highly skewed towards a preponderance of female hatchlings. Histopathologic findings in hatchling mortalities included severe, acute, multifocal, heterophilic bronchopneumonia with intralesional bacteria in 4/50 (8%) hatchlings. Data from this study guide conservation strategies by identifying risk factors and further avenues of research needed to support reproductive success of leatherback sea turtles in Grenada and the greater Caribbean region. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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15 pages, 4024 KiB

Open AccessArticle

Dietary Preferences of Loggerhead Sea Turtles (Caretta caretta) in Two Mediterranean Feeding Grounds: Does Prey Selection Change with Habitat Use throughout Their Life Cycle?

by Giulia Mariani, Fabio Bellucci, Cristiano Cocumelli, Caterina Raso, Sandra Hochscheid, Chiara Roncari, Eliana Nerone, Sara Recchi, Federica Di Giacinto, Vincenzo Olivieri, Simone Pulsoni, Marco Matiddi, Cecilia Silvestri, Nicola Ferri and Ludovica Di Renzo

Animals 2023, 13(4), 654; https://doi.org/10.3390/ani13040654 - 13 Feb 2023

Cited by 1 | Viewed by 2239

Abstract

According to their life stage, the loggerhead sea turtle (Caretta caretta) is found in a wide range of habitats, from neritic to more oceanic areas. Their feeding habits are expected to change as they develop, along with habitat use. Juvenile sea [...] Read more.

According to their life stage, the loggerhead sea turtle (Caretta caretta) is found in a wide range of habitats, from neritic to more oceanic areas. Their feeding habits are expected to change as they develop, along with habitat use. Juvenile sea turtles are hypothesized to feed on pelagic species in oceanic areas, shifting to more benthic prey during the subadult and adult stages. We analyzed the gastrointestinal content from 150 loggerhead sea turtles stranded and/or bycaught along the Adriatic coast of the Abruzzo and Molise regions (n = 89) and the Tyrrhenian coast of the Lazio and Campania regions (n = 61) from 2018 to 2021. Food items were identified to the lowest taxonomic level, and the frequency of occurrence was calculated for each taxon and most recurrent species to assess changes in prey selection during the development. The marine litter was categorized, and the frequency of occurrence was calculated for the ingestion of litter. The most recurrent taxonomic prey group recorded in the Adriatic sample was Arthropoda (94%), followed by Mollusca (63%) and Chordata (34%). In the Tyrrhenian sample, loggerhead sea turtles fed mostly on Mollusca (84%), Arthropoda (38%), and Chordata (26%). Surprisingly, the Adriatic-Tyrrhenian sample groups showed similar feeding behavior between juveniles, subadults, and adults. A similar correlation has been observed concerning the ingestion of litter. Moreover, this study confirms the opportunistic feeding behavior of loggerhead sea turtles and their high adaptability. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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19 pages, 2921 KiB

Open AccessArticle

Monitoring Green Sea Turtles in the San Gabriel River of Southern California

by Lynn M. Massey, Shannon Penna, Eric Zahn, Dan Lawson and Cassandra M. Davis

Animals 2023, 13(3), 434; https://doi.org/10.3390/ani13030434 - 27 Jan 2023

Viewed by 3774

Abstract

Effective conservation of endangered species relies on the characterization of habitat use and tracking of long-term population trends, which can be especially challenging for marine species that migrate long distances and utilize a diversity of habitats throughout their lives. Since 2012, citizen science [...] Read more.

Effective conservation of endangered species relies on the characterization of habitat use and tracking of long-term population trends, which can be especially challenging for marine species that migrate long distances and utilize a diversity of habitats throughout their lives. Since 2012, citizen science volunteers at the Aquarium of the Pacific in Long Beach, California, have been monitoring an urban population of East Pacific green sea turtles (Chelonia mydas) that resides near the mouth of the San Gabriel River (SGR) in Southern California, USA, in order to gain insights about how the population uses this area. Here, we collate and analyze nine years of citizen science data, including observed sightings collected across 10 observation stations. Our results confirm that green sea turtles are frequently present around warm water effluent from power plants, similar to research results reported for other locations in the eastern Pacific Ocean. Importantly, observational data also show notable green sea turtle activity around the outfalls for a small wetland habitat bordering the SGR, highlighting the importance of wetland ecosystems as a key habitat and foraging area for this threatened population. Finally, our results showcase the benefits of using citizen science to monitor sea turtle populations in easily accessible nearshore habitats. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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10 pages, 2473 KiB

Open AccessCommunication

Increased Prevalence and New Evidence of Multi-Species Chelonid Herpesvirus 5 (ChHV5) Infection in the Sea Turtles of Mabul Island, Borneo

by Dexter Miller Robben, Pushpa Palaniappan, Aswini Leela Loganathan and Vijay Kumar Subbiah

Animals 2023, 13(2), 290; https://doi.org/10.3390/ani13020290 - 14 Jan 2023

Cited by 2 | Viewed by 1778

Abstract

Fibropapillomatosis (FP) is a debilitating tumor disease affecting all species of sea turtles globally. The most probable etiological agent for FP is the chelonid herpesvirus 5 (ChHV5). A 2015–2016 field survey of the sea turtles at Mabul Island, Sabah, Malaysia, found three green [...] Read more.

Fibropapillomatosis (FP) is a debilitating tumor disease affecting all species of sea turtles globally. The most probable etiological agent for FP is the chelonid herpesvirus 5 (ChHV5). A 2015–2016 field survey of the sea turtles at Mabul Island, Sabah, Malaysia, found three green turtles (Chelonia mydas) with FP tumors. However, the presence of ChHV5 was confirmed in 7.8% (9/115) green turtles and was absent (0/16) in the hawksbill (Eretmochelys imbricata) turtles, as determined through molecular approaches. Subsequent to this, we managed to conduct field sampling of sea turtles in November 2019, just prior to the pandemic lockdown. Here, we aim to determine the extent of ChHV5 infection, and whether the virus has spread to other species of sea turtles around Mabul Island after the first reports of ChHV5 and FP. A total of 69 tissue samples were obtained from green (63), hawksbill (5), and olive ridley (Lepidochelys olivacea) (1) turtles in November 2019. We observed only one green turtle that exhibited FP tumors. To determine the presence of ChHV5, viral DNA was isolated from all the tissue samples, and polymerase chain reaction (PCR) analysis targeting three highly conserved regions of the virus, i.e., the capsid protein gene, glycoprotein H gene, and glycoprotein B gene, was performed. Out of 63 green turtles, 27 were positive for the presence of the virus. The prevalence of ChHV5 in the green turtles showed an increase of 42.9% as compared to the previous sampling conducted in 2015–2016. Additionally, for the first time, three out of the five hawksbill turtles, and one olive ridley turtle, were also PCR-positive for the virus. In conclusion, this study reveals that there has been an increase in ChHV5 infection among turtles in Mabul Island over the last 3 years. ChHV5 should be considered a potential threat, and mitigation efforts should be taken to prevent the spread of infection among the endangered sea turtles of Mabul Island and surrounding islands within the Coral Triangle. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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13 pages, 2936 KiB

Open AccessArticle

Marina Observation of Sea Turtles: Establishing a Database of Intracoastal Waterway Green Sea Turtles in Northeast Florida

by Edward McGinley, Avery Cogley, Leslie Palmer, Patricia McCaul, Lilli Longo, Jasmine Silvennoinen, Angela Martin, Josalyn Gomez, Sydney Bachmaier, Michaela Mackey, Chris Kao, Scott Eastman and Catherine Eastman

Animals 2023, 13(2), 279; https://doi.org/10.3390/ani13020279 - 13 Jan 2023

Viewed by 2680

Abstract

As conservation efforts regarding green sea turtles, Chelonia mydas, continue, it is imperative to document behaviors and foraging habits/habitats of understudied populations. We have conducted an 18-month study dedicated to photographing the local population feeding alongside floating docks within the Guana Tolomato Matanzas [...] Read more.

As conservation efforts regarding green sea turtles, Chelonia mydas, continue, it is imperative to document behaviors and foraging habits/habitats of understudied populations. We have conducted an 18-month study dedicated to photographing the local population feeding alongside floating docks within the Guana Tolomato Matanzas estuary to determine the capability of matching head scale patterns efficiently through a pattern matching program: HotSpotter. To date, 195 unique sea turtles have been identified between two different marinas located in St. Augustine, FL. Of these, 98 were spotted more than once, with 39 of them being “tracked” for longer than a year. Temperature trends were also monitored in conjunction, showing that more individuals appeared during the warmer months of the year. The evidence, overall, indicates that these locations host a resident population of green sea turtles, leading to the need for a discussion on potential threats originating from the usage of these marinas by humans. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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15 pages, 1979 KiB

Open AccessArticle

Size-Mediated Sea Turtle Behavioral Responses at Artificial Habitats in the Northern Gulf of Mexico

by Tabitha Renee Siegfried, Jackson Reimer, Emma Roberto, Christopher Noren, Alex Vidal, Kristi Dixon, Morgan DuBois and Susan E. Piacenza

Animals 2023, 13(1), 114; https://doi.org/10.3390/ani13010114 - 28 Dec 2022

Viewed by 2026

Abstract

Our understanding of size-specific sea turtle behavior has lagged due to methodological limitations. However, stereo-video cameras (SVC) are an in-water approach that can link body-size and allow for relatively undisturbed behavioral observations. In this study, we conducted SVC dive surveys at local artificial [...] Read more.

Our understanding of size-specific sea turtle behavior has lagged due to methodological limitations. However, stereo-video cameras (SVC) are an in-water approach that can link body-size and allow for relatively undisturbed behavioral observations. In this study, we conducted SVC dive surveys at local artificial reefs, piers, and jetties in the northern Gulf of Mexico (nGOM) from May 2019 to August 2021. Using SVCs, we measured sea turtle straight carapace length, documented behaviors, and quantified wariness by assessing minimum approach distance (MAD). In green sea turtles (Chelonia mydas), the observed MAD ranged from 0.72 to 5.99 m (mean 2.10 m ± 1.10 standard deviation (SD), n = 73). For loggerhead sea turtles (Caretta caretta), the MAD ranged between 0.93 and 3.80 m (mean 2.12 m ± 0.99 SD, n = 16). Kemp’s ridley sea turtles (Lepidochelys kempii) were similar to loggerheads, and MAD ranged from 0.78 to 3.63 m (mean 2.35 m ± 0.99 SD, n = 8). We then evaluated what biological factors could impact the MAD observed by species, but we excluded Kemp’s ridleys as the sample size was small. Using a linear mixed model and model selection based on AICc, the top ranked model for both green and loggerhead sea turtles included SCL as the most important factor influencing MAD. MAD did not vary with habitat type for either species. Our results showed that larger individuals, regardless of species, have a greater wariness response, becoming startled at greater distances than smaller individuals. The findings of our study support the use of SVC as an accessible, non-invasive tool to conduct ecologically relevant in-water surveys of sea turtles to link behavioral observations to body size. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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21 pages, 8018 KiB

Open AccessArticle

Trends in Reproductive Indicators of Green and Hawksbill Sea Turtles over a 30-Year Monitoring Period in the Southern Gulf of Mexico and Their Conservation Implications

by Melania C. López-Castro, Eduardo Cuevas, Vicente Guzmán Hernández, Ángeles Raymundo Sánchez, Rosa C. Martínez-Portugal, Diana J. Lira Reyes and Jorge Ángel Berzunza Chio

Animals 2022, 12(23), 3280; https://doi.org/10.3390/ani12233280 - 24 Nov 2022

Cited by 5 | Viewed by 2149

Abstract

Long-term monitoring programs of species at risk are efficacious tools to assess population changes, evaluate conservation strategies, and improve management practices to ensure populations reach levels at which they can fulfill their ecological roles. For sea turtles, annual nesting beach surveys are the [...] Read more.

Long-term monitoring programs of species at risk are efficacious tools to assess population changes, evaluate conservation strategies, and improve management practices to ensure populations reach levels at which they can fulfill their ecological roles. For sea turtles, annual nesting beach surveys are the most accessible method to estimating the population abundance and reproductive output, especially when these are done in primary nesting sites. However, little data exist on the long-term assessment of these parameters. Here, we present the trends of the nest abundance, female size, hatching, and emergence success of hawksbill (Eretmochelys imbricata) and green (Chelonia mydas) turtles at key nesting beaches in the southern Gulf of Mexico over 31 years (from 1990 to 2021). The nest abundance showed an increasing trend in both species as a result of the sustained protection and conservation effort, but there was no significant temporal trend in the annual female size, clutch size, hatching, and emergence success. However, these indicators showed decreasing mean values over the last decade and should be closely monitored. We suggest these decreases link to the combined effects of ocean warming and anthropogenic pressures affecting the sea turtle foraging grounds. Aside from protecting key nesting sites, protecting and restoring crucial foraging habitats should be an immediate priority requiring international cooperation. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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19 pages, 10585 KiB

Open AccessArticle

Genetics, Morphometrics and Health Characterization of Green Turtle Foraging Grounds in Mainland and Insular Chile

by Rocío Álvarez-Varas, Carol Medrano, Hugo A. Benítez, Felipe Guerrero, Fabiola León Miranda, Juliana A. Vianna, Camila González and David Véliz

Animals 2022, 12(12), 1473; https://doi.org/10.3390/ani12121473 - 07 Jun 2022

Cited by 1 | Viewed by 2944

Abstract

Two divergent genetic lineages have been described for the endangered green turtle in the Pacific Ocean, occurring sympatrically in some foraging grounds. Chile has seven known green turtle foraging grounds, hosting mainly juveniles of different lineages. Unfortunately, anthropic factors have led to the [...] Read more.

Two divergent genetic lineages have been described for the endangered green turtle in the Pacific Ocean, occurring sympatrically in some foraging grounds. Chile has seven known green turtle foraging grounds, hosting mainly juveniles of different lineages. Unfortunately, anthropic factors have led to the decline or disappearance of most foraging aggregations. We investigated age-class/sex structure, morphological variation, genetic diversity and structure, and health status of turtles from two mainland (Bahia Salado and Playa Chinchorro) and one insular (Easter Island) Chilean foraging grounds. Bahia Salado is composed of juveniles, and with Playa Chinchorro, exclusively harbors individuals of the north-central/eastern Pacific lineage, with Galapagos as the major genetic contributor. Conversely, Easter Island hosts juveniles and adults from both the eastern Pacific and French Polynesia. Morphological variation was found between lineages and foraging grounds, suggesting an underlying genetic component but also an environmental influence. Turtles from Easter Island, unlike Bahia Salado, exhibited injuries/alterations probably related to anthropic threats. Our findings point to establishing legal protection for mainland Chile’s foraging grounds, and to ensure that the administrative plan for Easter Island’s marine protected area maintains ecosystem health, turtle population viability, and related cultural and touristic activities. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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14 pages, 2271 KiB

Open AccessArticle

Minor Sea Turtle Nesting Areas May Remain Unnoticed without Specific Monitoring: The Case of the Largest Mediterranean Island (Sicily, Italy)

by Oleana Olga Prato, Valentina Paduano, Giulia Baldi, Salvatore Bonsignore, Gerlando Callea, Carlo Camera, Girolamo Culmone, Stefania D’angelo, Diego Fiorentino, Gino Galia, Salvatore Coriglione, Laura Genco, Giuseppe Mazzotta, Nicola Napolitano, Francesco Paolo Palazzo, Giuseppe Palilla, Santo Dylan Pelletti, Toni Mingozzi, Luigi Agresti and Paolo Casale

Animals 2022, 12(9), 1221; https://doi.org/10.3390/ani12091221 - 09 May 2022

Cited by 6 | Viewed by 3080

Abstract

Identifying coastal tracts suitable for sea turtle reproduction is crucial for sea turtle conservation in a context of fast coastal development and climate change. In contrast to nesting aggregations, diffuse nesting is elusive and assessing nesting levels is challenging. A total of 323 [...] Read more.

Identifying coastal tracts suitable for sea turtle reproduction is crucial for sea turtle conservation in a context of fast coastal development and climate change. In contrast to nesting aggregations, diffuse nesting is elusive and assessing nesting levels is challenging. A total of 323 nesting events by the loggerhead sea turtle Caretta caretta have been reported in Sicily, the largest Mediterranean island, in the 1944–2021 period, mostly in the last decade. Specific monitoring efforts are the most likely explanation for such an increase and shows that sea turtle nesting may be underestimated or completely ignored in many areas with scattered nesting. The real nesting level along the 464 km sandy shores of Sicily is still unknown and more research is needed. The observed incubation period was relatively long (57 d) suggesting that a majority of males are produced in Sicily, in contrast to the typical female-biased sex ratio of sea turtles. In a context of climate warming producing sex ratios more skewed towards females, the potential of Sicily as a male-producing area should be further investigated. Other reproductive parameters are provided, such as clutch size and hatching and emergence success. A negative effect of relocation on the latter two was observed. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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9 pages, 1551 KiB

Open AccessBrief Report

A Preliminary Report of Plastic Ingestion by Hawksbill and Green Turtles in the Saudi Arabian Red Sea

by Lyndsey K. Tanabe, Jesse E. M. Cochran, Royale S. Hardenstine, Kirsty Scott and Michael L. Berumen

Animals 2023, 13(2), 314; https://doi.org/10.3390/ani13020314 - 16 Jan 2023

Cited by 1 | Viewed by 2526

Abstract

(1) Background: Plastic pollution is a major environmental concern confronting marine animals. Sea turtles are considered a bio-indicator of plastic pollution, but there is little information regarding plastic ingestion by turtles in the Red Sea. With large-scale development projects being built along the [...] Read more.

(1) Background: Plastic pollution is a major environmental concern confronting marine animals. Sea turtles are considered a bio-indicator of plastic pollution, but there is little information regarding plastic ingestion by turtles in the Red Sea. With large-scale development projects being built along the Saudi Arabian coast, it is important to have a baseline for plastic ingestion before construction is complete. (2) Methods: Ten deceased sea turtles (four hawksbill and six green turtles) were collected along the Saudi Arabian coastline. Necropsies were conducted, and the entire gastrointestinal tracts were extracted and the contents were passed through a 1 mm mesh sieve. (3) Results: We found that 40% of the turtles in this study had ingested plastics. Thread-like plastics were the most common plastic category, and multi-colored was the most prevalent color category. (4) Conclusions: Monitoring of the plastic ingestion by marine megafauna should be conducted as a long-term assessment of the developments’ impacts. Additionally, conservation efforts should be focused on removing plastics (namely ghost nests and fishing lines) from the reefs and reducing the amount of plastic entering the sea. Full article

(This article belongs to the Special Issue Sea Turtles: Ecology, Distribution, and Conservation)

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