Heart rate reduction during voluntary deep diving in free-ranging loggerhead sea turtles.

Air-breathing vertebrates exhibit cardiovascular responses to diving including heart rate reduction (diving bradycardia). Field studies on aquatic mammals and birds have shown that the intensity of bradycardia can vary depending on diving behaviour, such as the depth of dives and dive duration. However, in aquatic reptiles, the variation in heart rate during deep dives under natural conditions has not been fully investigated. In this study, we released five loggerhead sea turtles (Caretta caretta) outfitted with recorders into the sea and recorded their electrocardiogram, depth, water temperature and longitudinal acceleration. After 3 days, the recorders automatically detached from the turtles. The heart rate signals were detected from the electrodes placed on the surface of the plastron. The mean (±s.d.) heart rate of 12.8±4.1 beats min-1 during dives was significantly lower than that of 20.9±4.1 beats min-1 during surface periods. Heart rate during dives varied with dive depth, although it remained lower than that at the surface. When the turtle dived deeper than 140 m, despite the relatively high flipper stroke rate (approximately 19 strokes min-1), the heart rate dropped rapidly to approximately 2 beats min-1 temporarily. The minimum instantaneous heart rate during dives was lower at deeper dive depths. Our results indicate that loggerhead sea turtles show variations in the intensity of diving bradycardia depending on their diving behaviour, similar to that shown by marine mammals and birds.

Marine turtles as bio-indicators of plastic pollution in the eastern Mediterranean.

The loggerhead turtle (Caretta caretta) has been suggested as a bio-indicator species for plastic pollution. However, detailed investigations in the eastern Mediterranean are limited. Here, we present data from loggerhead turtles (2012-2022; n = 131) of which 42.7 % (n = 57) had ingested macroplastic (pieces ≥ 5 mm). Frequency of occurrence (%) was not found to have changed over time, with body size (CCL cm), between stranded or bycaught turtles, or with levels of digesta present. The characteristics of ingested plastic (n = 492) were largely sheetlike (62 %), clear (41 %) or white (25 %) and the most common polymers identified were Polypropylene (37 %) and Polyethylene (35 %). Strong selectivity was displayed towards certain types, colours and shapes. Data are also presented for posthatchling turtles (n = 4), an understudied life stage. Much larger sample sizes will be needed for this species to be an effective bio-indicator, with the consideration of monitoring green turtles (Chelonia mydas) for the eastern Mediterranean recommended allowing a more holistic picture to be gathered.

Iatrogenic gas embolism in a juvenile loggerhead sea turtle (Caretta caretta).

A mild pneumocoelom was diagnosed by computed tomography in a stranded juvenile loggerhead sea turtle (Caretta caretta). After gas extraction by ultrasound-guided puncture, the animal did not improve and was subjected to hyperbaric oxygen therapy (HBOT). After HBOT, the turtle developed marked subcutaneous emphysema and was found dead the following morning. Gross lesions included a distended right atrium with numerous gas bubbles within the epicardium, gas bubbles in the hepatic, gastric and mesenteric veins, a small gas-filled bulla in the left lung and diffuse haemorrhages in the encephalon. Histological lesions included gas-like emboli in the lumen of the right atrium with myocardial necrosis, gas-like emboli in the lumina of intestinal, pulmonary and renal blood vessels and severe meningeal haemorrhages. From a forensic pathology perspective, the subcutaneous emphysema of immediate onset after HBOT and the greater severity of the histological lesions in blood vessels, heart, lung and brain differentiate this case from other cases of gas embolism in turtles due to incidental capture. Two factors contributed to this outcome: the existence of a probably unresolved pneumocoelom and the application of HBOT without an initial diagnosis that accurately indicated its use. Therefore, as in human medicine, the use of HBOT in sea turtles with lung lesions and pneumocoelom is discouraged. This is the first description of an iatrogenic gas embolism in a sea turtle.

Assessing microplastics contamination in unviable loggerhead sea turtle eggs.

Sea turtles, in comparison with marine mammals, sea birds, and fishes, are the most affected by microplastics in terms of number of individuals impacted and concentration within each organism. The ubiquitous nature and persistence of microplastics in the environment further compromises sea turtles as many species are currently vulnerable, endangered, or critically endangered. The objective of this study was to quantify microplastic contamination in unviable loggerhead sea turtle eggs (Caretta caretta). Eggs were collected from seven locations along the northwest coast of Florida. A total of 70 nests and 350 eggs were examined. Microplastics (n = 510) were found in undeveloped loggerhead sea turtle eggs across all seven sites, suggesting that maternal transference and/or exchange between the internal and external environment were possible. The frequency found was 7.29 ± 1.83 microplastic pieces per nest and 1.46 ± 0.01 per egg. Microplastics were categorized based on color, shape, size, and type of polymer. The predominant color of microplastics were blue/green (n = 236), shape was fibers (n = 369), and length was 10-300 µm (n = 191). Identified fragments, films, beads and one foam (n = 187) had the most common area of 1-10 µm2 (n = 45). Micro-Fourier Transform Infrared (µ-FTIR) spectroscopy analysis demonstrated that polyethylene (11 %) and polystyrene (7 %) were the main polymer types. For the first time microplastics were found in unviable, undeveloped loggerhead sea turtle eggs collected in northwest Florida. This work provides insight into the distribution patterns of microplastic pollutants in loggerhead sea turtle eggs and may extend to other species worldwide.

Doce river mining tailings can be an influencing factor in loggerhead turtles reproductive success in Brazil.

In November 2015, a tailings dam ruptured and affected the second largest nesting site of loggerhead sea turtles in Brazil. This study aimed to evaluate the reproductive success, and trace elements in female's plasma, freshly laid eggs, unhatched eggs, and dead hatchlings of loggerhead turtles that nest in the coastal area exposed to the mining waste (Povoação, Espírito Santo state) and compare them with animals from an area that was not affected by the tailings (Praia do Forte, Bahia state). Plasma concentrations of As, Cd, Cr, Fe, and Zn were significantly higher in samples from Povoação in comparison to turtles from Praia do Forte. In Povoação, unhatched eggs and dead hatchlings had higher As, Cu, Hg, Mn, and Zn concentrations than freshly laid eggs, and trace elements correlated with the hatching and emergence success. Our findings suggest that the higher concentrations of some metals may influence the incubation period and reproductive success of loggerheads in the affected area.

Can plastic pollution contaminate loggerhead turtle nests? Evaluation of flame retardants (PBDEs) levels in the sand.

Plastic pollution is a global environmental issue affecting multiple ecosystems, namely sea turtle nesting grounds. We analysed the potential chemical contamination caused by plastic debris in loggerhead turtle (Caretta caretta) nests, focusing on polybrominated diphenyl ethers (PBDEs, a class of flame retardants). For that, we conducted a field experiment in a turtle hatchery (Cabo Verde) by placing plastic fragments in the nests at two depths: surface and ~20 cm. We evaluated the nests' success and quantified the levels of PBDEs in the sand using GC-MS/MS. Our results suggest that plastics on the nests' surface can leak contaminants, infiltrating the sand up to 20 cm. Buried plastics showed no relevant leakage of chemicals. While hatching and emergence success was unaffected, we found a relationship between leucistic embryos and contamination levels. Our study highlights the threats of plastic accumulation on beaches, which can potentially leak chemicals and contaminate turtle nests.

Comparative study of polycyclic aromatic hydrocarbons (PAHs) in salt gland and liver of loggerhead turtle Caretta caretta (Linnaeus, Cheloniidae) stranded along the Mediterranean coast, Southern Italy.

The levels of polycyclic aromatic hydrocarbons, PAHs, were determined in the liver and salt gland of 19 loggerhead turtles (Caretta caretta Linnaeus, Cheloniidae) stranded along the coasts of the south Tyrrhenian Sea, Italy, from 2019 to 2021. The 16 EPA's priority PAHs were determined by gas chromatography coupled with mass spectrometry (GC-MS). The average values of ΣPAHs in liver, 139 ± 55.0, were exceptionally high and up to one hundred times those of literature and appeared even more worrying in salt gland, 320 ± 97.6 ng/g, w.w. Naphthalene was the predominant contributor to PAHs richness and accounted for 90.0% and 93.7% of ΣPAHs in the two matrices, highlighting the petrogenic source of exposure. An overall higher bioaccumulation of NAP, more than two-fold, was detected in salt gland and especially in female and adults. Data of PAHs richness highlighted a potential risk of neoplastic disease development and that anthropogenic activities may seriously impair healthy state conditions of C. caretta. populations in south Tyrrhenian Sea.

Do loggerhead sea turtle (Caretta caretta) gut contents reflect the types, colors and sources of plastic pollution in the Southwest Indian Ocean?

We analyzed plastic debris ingested by loggerheads from bycatch between 2007 and 2021 in the Southwest Indian Ocean (SWIO). We also analyzed plastic debris accumulated on beaches of the east coast of Madagascar as a proxy for ocean plastics to compare the characteristics of beached plastics and plastic ingested by turtles. We conducted a "brand audit" of the plastics to determine their country of origin. An oceanic circulation model was used to identify the most likely sources of plastics in the SWIO. In total, 202 of the 266 loggerheads analyzed had ingested plastics. Plastics categorized as "hard" and "white" were equally dominant in loggerheads and on beaches, suggesting no diet selectivity. Both the brand audit and circulation modeling demonstrated that Southeast Asia is the main source of plastic pollution in the region. This study demonstrates that loggerheads can be used as bioindicators of plastic pollution in the SWIO.

The genome sequence of the Loggerhead sea turtle, Caretta caretta Linnaeus 1758.

We present a genome assembly of Caretta caretta (the Loggerhead sea turtle; Chordata, Testudines, Cheloniidae), generated from genomic data from two unrelated females. The genome sequence is 2.13 gigabases in size. The assembly has a busco completion score of 96.1% and N50 of 130.95 Mb. The majority of the assembly is scaffolded into 28 chromosomal representations with a remaining 2% of the assembly being excluded from these.

Balaenophilus manatorum in Debilitated and Bycatch-Derived Loggerhead Sea Turtles Caretta caretta from Northwestern Adriatic Sea.

Balenophilus manatorum (Copepoda: Harpaticoida) is one of the few components of the epibiontic fauna of Caretta caretta that show a "true" parasitic association with their host. From rrosive to ulcerative cutaneous lesions may seldom appear as a consequence of the copepod feeding on keratin on turtles' skin. Debilitating Turtle Syndrome (DTS) is the final outcome of a chronic insufficient assumption of nutrients, generally occurring with the impairment of immune functions and high epibiota burdens. In this survey, the presence of B. manatorum in C. caretta from the Northwestern Adriatic Sea was investigated and the relation between infection indices and the co-occurrence of DTS was studied. Clinical examination was performed at the time of rescue, including routine hematological assessment; external parasites were isolated mechanically from turtles' skin and morphologically identified through observation with an optic microscope and SEM. Ten turtles were classified as affected by DTS, all of them being small juveniles with typical clinical and clinicopathological presentation. A higher prevalence, abundance, and density of infection were found in turtles affected by the syndrome. The presence of massive skin coverage by the burrowing barnacle Pletylepas hexastylos prevented a proper evaluation of the pathology associated with B. manatorum in turtles affected by DTS. In any event, eventual skin damages caused by the parasite may represent a port of entry for secondary infections in such immunocompromised animals. Therefore, infection by B. manatorum should not go overlooked in debilitated turtles and should be opportunely treated.

Trace and macro elements concentrations in the blood and muscle of loggerhead turtles (Caretta caretta) from the Canary Islands, Spain.

Sea turtles can bioaccumulate heavy metals and trace elements over the years, therefore they can be used as bioindicators of pollution in the marine environment. The aim of this study was to analyze seventeen elements in blood and muscle of Caretta caretta from the Canary Islands and compare these concentrations in the two tissues. Thirteen blood samples and six muscle samples were collected from loggerhead turtles admitted to the Rescue Center of La Tahonilla. The samples were processed through microwave digestion and incineration. For the study of the data, a descriptive statistical analysis and a PERMANOVA were performed. All individuals in this study were juveniles (size <70 cm). The results of this study differ from previous studies on loggerhead sea turtles. All the elements analyzed were detected, with Na having the highest concentration in blood (75,379 ± 30,066 mg/kg) and muscle (222,626 ± 156,049 mg/kg). Statistically significant differences were found between the concentration of Al, B, Ba, Ca, Fe, K, Na, Sr, V and Zn in each tissue analyzed. Compared to other studies, a higher Cu concentration was found both in blood (252.9 ± 114.4 mg/kg) and in muscle (416 ± 247.8 mg/kg). This study has provided new data on pollutants in loggerhead sea turtles and increased the information available for different geographic areas, although more studies are needed to understand the effects and impact of these pollutants on sea turtles.

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.

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.

Repeated Biting by a Mediterranean Loggerhead Sea Turtle.

Mediterranean loggerhead sea turtles (Caretta caretta) are very large. During spawning season, they land on the beaches of Turkey and Greece at night, which are frequently visited by humans, and lay their eggs. Typically, they suck feed in deep water. It is uncommon for C caretta, which have strong mouths and jaws, to attack people. We report a case of a 44-y-old female patient who was attacked by a turtle on the Mediterranean beach in September 2020. She was brought to the emergency department, where she was noted to have a deep cut on the thumb and large bruises on the left side of her waist. The patient was discharged with appropriate wound care, antibacterial drug, and tetanus vaccine. The wound healed within a few months by developing granulation tissue. However, this report draws attention to the fact that, under some circumstances, C caretta can become aggressive toward people swimming off heavily populated beaches.

Correlation Between Microbial Community and Hatching Failure in Loggerhead Sea Turtle Caretta caretta.

Microbial communities provide essential information about host ecology and could be helpful as a tool to improve species conservation efforts. However, microbes can also infect and compromise the host development process and viability. Caretta caretta is the most widespread marine turtle species in the Mediterranean basin and is the only species of sea turtle nesting along the Italian coasts. Little is known about the microbiota composition of the nest of sea turtles and its correlation with hatching failures. In this study, the microbial composition of two nests of C. caretta featuring different rates of hatching success from a nesting beach in Lampedusa (Italy) was analyzed and compared. The bacterial community was determined using culture-dependent methods and next-generation sequencing based on 16S rRNA gene metabarcoding analysis. Our results showed five dominant bacterial phyla (Proteobacteria, Bacteroidetes, Actinobacteria, Verrucomicrobia, and Firmicutes) and indicated different bacterial families (Pseudomonadaceae and Brucellaceae) as likely causes of hatching failures. Besides, our findings demonstrated the nests' active role in modulating the sand's bacterial communities. This study suggests microbiological analysis could be a valuable tool in monitoring nests to take preventive actions and reduce hatching failures.

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

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.

Toxic metals in Loggerhead sea turtles (Caretta caretta) stranded freshly dead along Sicilian coasts.

BACKGROUND: The Loggerhead sea turtle (Caretta caretta) is a marine reptile belonging to a monophyletic group of chelonians. As these animals are long-lived, they have the ability to accumulate pollutants. AIM: To collect epidemiological data on toxic metals in marine Loggerhead sea turtles. MATERIALS AND METHODS: Forty Loggerhead sea turtles comprising 25 males and 15 females stranded freshly dead between 2013 and 2018 along the coasts of Sicily, Southern Italy, were examined for arsenic, cadmium, and lead accumulation in muscle and adipose tissues by means of a validated ICP-MS method. A modified K index as a growth condition factor, namely Fulton's K index, was used. Samples were tested in duplicate. A Wilcoxon rank sum test was carried out to evaluate metal contents differences between muscle and adipose tissues and between genders. RESULTS: The Fulton's K index suggested a good body condition of the C. caretta recovered with mean values of 5.34 ± 3.40 (n = 40; ±SD). Detectable concentrations of lead were found in 70% of the samples analysed with mean values of 0.65 ± 1.67 mg/kg wet weight and 0.51 ± 1.29 mg/kg wet weight in muscle and adipose tissues, respectively. No significant differences in arsenic, cadmium, and lead were detected between genders. In addition, no significant correlation was found between modified K index and concentrations of arsenic, cadmium, and lead. CLINICAL RELEVANCE: Findings on muscle and adipose tissues suggest chronic exposure of Caretta caretta to high concentrations of especially lead which might negatively affect health and welfare of these marine turtles although body condition was good.

Chlorinated Persistent Organic Pollutants (PCDD/Fs and PCBs) in Loggerhead Sea Turtles Stranded along the Central Adriatic Coast.

Persistent organic pollutants are widespread in the marine environment. They can bioaccumulate and biomagnify in marine organisms through the food web with a potentially toxic effect on living organisms. The sea turtle Caretta caretta is a carnivorous animal with opportunistic feeding behavior. These turtles tend to bioaccumulate pollutants through food, and hence they can be considered an indicator of chemical pollutants in the marine ecosystem. In this study, 44 loggerhead sea turtles were considered, and liver and fat tissue were sampled from each of them to investigate the levels of dioxins (PCDD/Fs) and polychlorinated biphenyls (PCBs) in sea turtles and their potential correlation with sex and size in terms of curved carapace length (CCL). Results suggested that these contaminants were easily bioaccumulated, and PCBs were predominant compared to dioxins in both liver and fat tissue. The congener patterns were similar to those found in sea fish. Moreover, there were no differences in the contamination levels between females and males, nor was there a correlation with the size. There is a need to harmonize the methodological approaches to better evaluate the results and trends over time and to monitor the species and indirectly the health status of the marine environment.

Bacterial diversity of loggerhead and green turtle eggs from two major nesting beaches from the Turkish coast of the Mediterranean.

This study was conducted during the 2018 nesting season at the Sugözü Beaches (Adana-Turkey) and Göksu Delta (Mersin-Turkey). Egg samples (n = 63) from loggerhead and green turtle nests (n = 43) were collected. Isolated bacteria were initially identified by phenotypic methods and then by MALDI-TOF MS. The bacterial mass spectra were analyzed using Principal Component Analysis. Bacterial isolation was performed for 55 isolates belonging to 12 genera from two major nesting sites. In Sugözü Beaches 62.2% of the bacteria species belonged to Enterobacteriaceae and in Göksu Delta 44.4% of the bacteria species belonged to Morganellaceae. Klebsiella oxytoca and Staphylococcus haemolyticus had not previously been detected in any sea turtle nests. This is the first MALDI-TOF MS study conducted for determination of bacterial variability in loggerhead turtle eggs in Turkey and serves as a reference study for the assessment of bacterial threat in sea turtle nests, enabling the establishment of suitable conservation measures and treatment processes for both sea turtles and nesting sites.

First Report of Septicaemic Listeriosis in a Loggerhead Sea Turtle (Caretta caretta) Stranded along the Adriatic Coast: Strain Detection and Sequencing.

Although there are increasing reports on the prevalence of Listeria monocytogenes in wild species, this is the first case of listeriosis in sea turtle. An adult female Caretta caretta was rescued after being stranded alive along the coast of the Abruzzo region (Italy) in summer 2021. The turtle died in 6 days due to respiratory failure. The necropsy showed widespread organ lesions, such as yellow foci of necrosis in many organs, gastrointestinal erosions, pericarditis, and granulomatous pneumonia. Microbiological and histological analyses were performed on several organs. Listeria monocytogenes was isolated from multiple organs, indicating a case of septicaemic listeriosis, and the genome was sequenced and characterized. All the colonies analysed belonged to the same strain serogroup IVb, ST388, and CC388.

Satellite-tracking dataset of loggerhead sea turtles tracked from western Mediterranean.

We provide the raw data of 44 satellite-tracked loggerhead sea turtles from different life-stages collected between 2016 and 2018. Depending on life-stage and tag availability a different satellite tag was attached to the loggerhead carapace. Location data were collected using the Argos system. We made publically available for the first time in the Mediterranean: (i) the satellite-tracking data for 17 one-year-aged post-hatchlings of loggerhead sea turtle came from two nests laid on the Mediterranean Spanish coast; (ii) the satellite-tracking data for 4 loggerhead nesting females collected from nesting events occurred on the Spanish Mediterranean coast. Besides, another 23 juvenile and adult loggerhead sea turtles were monitored and their data were made also available. Our dataset provide the turtle identity name or number, the date and coordinates of the location data, and the Argos location class associated. Our data contribute to the knowledge about the spatial use of the loggerhead sea turtle in the Mediterranean Sea and could be used in further analysis regarding habitat use and dispersal of this species in the Mediterranean Sea. Specially, nesting females and post-hatchlings data contribute to shed light about these life-stages related to nesting events out of the usual nesting range in the western Mediterranean, for which data still remains scarce. Also, data could be compared to further similar research in satellite-tracking loggerhead sea turtles in the Mediterranean basin.