Loggerhead Turtle Hatchlings Research Articles

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.

Plastic pollution can affect the emergence patterns of loggerhead turtle hatchlings

AbstractCoastal urbanization, plastic pollution and climate change are increasingly affecting marine turtles' nesting habitats. In addition to facing risks of mortality due to saltwater inundation or predation, their eggs and hatchlings' might also be affected by plastic debris accumulation on beaches, but no studies to date have analysed such impact. To analyse whether plastic pollution on nests' surfaces affects the embryos' and hatchlings' survival odds, we designed a field experiment in a turtle hatchery on a nesting beach of the loggerhead turtle (Caretta caretta) in Boa Vista Island (Cabo Verde). We applied three treatments with distinct plastic levels (18 nests per treatment): control (no added plastics), low density (64 plastic fragments with 24.5 g of plastic weight per nest) and high density (128 plastic fragments with 49.0 g of plastic weight per nest). Then, we tested 16 variables related to the incubation period, emergence period and hatchlings' fitness. Our results suggest that nests with high plastic density have a significantly lower probability of successful emergence. Moreover, plastics also affected the synchronized emergence of hatchlings, with more scattered and smaller emergent groups, which might increase the predation risk. Considering that turtle nesting habitats are becoming increasingly threatened, this additional threat might compromise the survival of turtle hatchlings on beaches.

Warmer air temperatures do not negatively affect body size and emergence success of loggerhead turtle (Caretta caretta) hatchlings at Yakushima Island, Japan, the largest rookery in the North Pacific

Warmer air temperatures do not negatively affect body size and emergence success of loggerhead turtle (Caretta caretta) hatchlings at Yakushima Island, Japan, the largest rookery in the North Pacific

New fossil sea turtle trackway morphotypes from the Pleistocene of South Africa highlight role of ichnology in turtle paleobiology

AbstractMore than 130 late Pleistocene trackway sites from the coastal eolianites and beach deposits of the Cape south coast, South Africa, have previously mostly yielded tracks of large mammals and birds. However, two sites east of Still Bay, and a third near Garden Route National Park, yield distinctive trackways of hatchling sea turtles, made during the short posthatching (postemergence) interval when the trackmakers headed for the sea. One assemblage of approximately parallel trackways indicates smaller loggerhead turtle hatchlings, with alternating gaits, and contrasts with a wider trackway indicating a leatherback turtle hatchling. These are the world's first reports of fossil traces that document this brief “run-for the-sea” phenomenon. They help delineate late Pleistocene sea turtle breeding ranges and indicate climatic conditions along the Cape south coast. Ichnotaxonomically defined swim tracks of large adult sea turtles are known from a few Mesozoic sites. Likewise, walking and swim traces of terrestrial freshwater turtles are also known from the Mesozoic and Cenozoic. However, as no ichnotaxonomy exists for these diagnostic hatchling trails, we assign the trackways of the inferred loggerheads to the new ichnotaxonAustralochelichnus agulhasiiichnogen. et ichnosp. nov., and the inferred leatherback trackway toMarinerichnus latusichnogen. et ichnosp. nov.

Effects of sand type on hatch, emergence, and locomotor performance in loggerhead turtle hatchlings

While numerous problems have been identified regarding artificial management of sea turtle eggs, the development of methods and techniques for rearing the eggs, such as relocation and incubation in hatcheries, should be considered an effective approach for the conservation of sea turtles. As sand size is hypothesized to affect the timing of the nest-atrium collapse and hatchling fatigue, one of the important aspects of incubation environment in the hatchery is likely sand. We examined the influence of nest-sand type on hatching characteristics and hatchling quality in loggerhead turtles (Caretta caretta). We collected the eggs from nine nests in the wild and incubated them in two kinds of sand groups in a hatchery. One group of eggs was incubated in fine sand and the other was incubated in coarse sand. Compared to the nests comprising coarse sand, hatchlings from fine-grain sand nests had significantly higher crawling and swimming performance. To increase hatchling survival and performance, fine-grain sand is recommended for use in incubation beds in artificial hatcheries.

Mass-stranding suggests natal area and migration of loggerhead turtle hatchlings in the Sea of Japan

Mass-stranding suggests natal area and migration of loggerhead turtle hatchlings in the Sea of Japan

Histochemical and immunohistochemical studies of the gonads and paramesonephric ducts of male and female hatchlings of loggerhead sea turtles (Caretta caretta)

The sex of neonatal sea turtles is difficult to determine, because neonates lack heteromorphic sex chromosomes and dimorphic external characteristics; internal dimorphic morphology is defined at hatching. We used histochemical staining and made measurements in the gonads and paramesonephric ducts (PD) of both sexes to determine structural differences in female and male loggerhead sea turtle (Caretta caretta) hatchlings. We detected differences in the gonads and PD between the sexes including the amounts of mucopolysaccharides, collagen and elastic fibers. We determined that the thickness of the gonadal cortex and the diameter of the PD lumen are reliable sex-specific characteristics. We also assessed immunolocalization of aromatase, an enzyme complex that converts androgens to estrogens, and found differences in the localization and intensity of aromatase immunostaining in the gonads and PD of female and male hatchlings. Comprehensive studies of the sexual differences of sea turtles are important for conservation programs.

An assessment of ‘turtle-friendly' lights on the sea-finding behaviour of loggerhead turtle hatchlings (Caretta caretta)

Context It is well established that artificial light can disrupt the sea-finding ability of sea turtle hatchlings, and some manufactures are now marketing ‘turtle-friendly’ lights that are supposed to be minimally disruptive to this sea-finding behaviour. However, there have been no studies that have tested whether ‘turtle-friendly’ lights are benign to hatchling sea turtle sea-finding ability. Aims We tested two different types of ‘turtle-friendly’ lights (LED amber-light peak intensity 620 nm and LED red-light peak intensity 640 nm) to see whether they are disruptive to the sea-finding ability of eastern-coast Australian loggerhead turtle hatchlings. Methods Using standard circular-arena experiments, we assessed the directional preference of newly emerged loggerhead turtle hatchlings from the Woongarra Coast of Queensland, Australia, during different moon phases without artificial lighting and in the presence of ‘turtle-friendly’ lights. Key results Contrary to expectations, sea-finding ability of hatchlings was disrupted by the amber lights, particularly in the absence of a moon. The less intense red lights were less disruptive to hatchlings; however, misorientation and disorientation events still occurred when lights were within 4 m of hatchlings. The disruptive impact on sea-finding ability increased with the cumulative impact of multiple lights increasing light intensity. Conclusions The ‘turtle-friendly’ lights we used disrupted the sea-finding ability of eastern-coast Australian loggerhead turtle hatchlings, with the most pronounced disruption occurring under moonless conditions. Implications The use of amber and red LED lights adjacent to the nesting beaches of loggerhead sea turtles should be managed because this lighting has the potential to disrupt the sea-finding ability of sea turtle hatchlings.

Incubation temperature, morphology and performance in loggerhead (Caretta caretta) turtle hatchlings from Mon Repos, Queensland, Australia.

Marine turtles are vulnerable to climate change because their life history and reproduction are tied to environmental temperatures. The egg incubation stage is arguably the most vulnerable stage, because marine turtle eggs require a narrow range of temperatures for successful incubation. Additionally, incubation temperature affects sex, emergence success, morphology and locomotor performance of hatchlings. Hatchlings often experience high rates of predation in the first few hours of their life, and increased size or locomotor ability may improve their chances of survival. Between 2010 and 2013 we monitored the temperature of loggerhead (Caretta caretta; Linnaeus 1758) turtle nests at Mon Repos Rookery, and used these data to calculate a mean three day maximum temperature (T3dm) for each nest. We calculated the hatching and emergence success for each nest, then measured the mass, size and locomotor performance of hatchlings that emerged from those nests. Nests with a T3dm greater than 34°C experienced a lower emergence success and produced smaller hatchlings than nests with a T3dm lower than 34°C. Hatchlings from nests with a T3dm below 34°C performed better in crawling and swimming trials than hatchlings from nests with a T3dm above 34°C. Thus even non-lethal increases in global temperatures have the potential to detrimentally affect fitness and survival of marine turtle hatchlings.

Stable isotope relationships between mothers, eggs and hatchlings in loggerhead sea turtles Caretta caretta

In the past two decades, stable isotope analysis (SIA) has been increasingly used to infer dietary ecology and habitat use in sea turtles. Tissue samples for SIA are often collected from adult females during a nesting event because turtles are easily accessible then. However, this sampling opportunity can be easily missed, or the female may be disturbed during the nesting event and abandon nest construction. The current research assessed the relationships of carbon and nitrogen stable isotope values between mothers, and their eggs and hatchlings of loggerhead turtles Caretta caretta to evaluate the accuracy of using eggs or hatchlings in inferring the mothers’ stable isotope values. Whole blood and epidermis from mothers (n = 5), yolk, albumen and shell in their eggs (n = 5 per female) and epidermis, whole blood, liver, muscle and residual yolks in their hatchlings (n = 5 for 3 females) were collected from loggerhead turtles in the 2012/2013 nesting season at Mon Repos sea turtle rookery (24°47′46″S; 152°26′26″E), in South East Queensland, Australia. The effect of lipid extraction on isotopic values in sampled tissues was also evaluated. Lipid extraction had a significant effect on δ13C values for egg yolk, residual yolk and liver, but also altered δ15N values for these tissues. Significant correlations were found between adult tissues and both their egg-yolk and hatchling tissues. Isotopic values of fresh egg yolk sampled straight after oviposition and residual yolk internalized by hatchlings at hatching were similar, implying that the stable isotope values of yolk remains unchanged throughout embryonic development. Stable isotope values were distinct between different tissues sampled from the same hatchling. With the caution that our results are based on a small sample size (n = 3), they support the method of sampling hatchlings, or eggs, rather than nesting females, to infer information about the feeding habits and migratory patterns of nesting turtle populations.

Nano-tags for neonates and ocean-mediated swimming behaviours linked to rapid dispersal of hatchling sea turtles.

Dispersal during juvenile life stages drives the life-history evolution and dynamics of many marine vertebrate populations. However, the movements of juvenile organisms, too small to track using conventional satellite telemetry devices, remain enigmatic. For sea turtles, this led to the paradigm of the 'lost years' since hatchlings disperse widely with ocean currents. Recently, advances in the miniaturization of tracking technology have permitted the application of nano-tags to track cryptic organisms. Here, the novel use of acoustic nano-tags on neonate loggerhead turtle hatchlings enabled us to witness first-hand their dispersal and behaviour during their first day at sea. We tracked hatchlings distances of up to 15 km and documented their rapid transport (up to 60 m min(-1)) with surface current flows passing their natal areas. Tracking was complemented with laboratory observations to monitor swimming behaviours over longer periods which highlighted (i) a positive correlation between swimming activity levels and body size and (ii) population-specific swimming behaviours (e.g. nocturnal inactivity) suggesting local oceanic conditions drive the evolution of innate swimming behaviours. Knowledge of the swimming behaviours of small organisms is crucial to improve the accuracy of ocean model simulations used to predict the fate of these organisms and determine resultant population-level implications into adulthood.

Histological and histochemical features of the small intestine in loggerhead sea turtle hatchlings (Caretta caretta)

Loggerheads (Caretta caretta) are endangered marine turtles and basic research is an essential component of conservation. In an attempt to provide further information in this field, we aimed to identify the microscopic morphological and histochemical features of the small intestine in the loggerhead turtle. Four loggerhead turtle hatchlings were used in this study; due to the loggerhead’s endangered status, this study was performed with dead animals. During necropsy, the cranial and caudal portions of the small intestine were obtained. The samples were embedded in paraffin and stained using the following techniques: Hematoxylin and Eosin, Gomori’s trichrome, Periodic acid-Schiff reactive (PAS), Alcian blue (pH 1.0 and pH 2.5), PAS-Alcian blue, Toluidine blue (pH 4.5 and pH 3.5), Giemsa, colloidal iron, Perl’s blue, Wilder’s impregnation, Methenamine silver, Grimelius and Masson-Fontana. The intestinal mucosa present plicae featuring a pseudostratified columnar epithelium with abundant blood vessels and abundant lymphatic vessels in the submucosa; both of these observations represent the main histological findings. The secretory granules in the goblet cells demonstrated the following characteristics: in the cranial portion, neutral mucopolysaccharides, sulfated acid mucopolysaccharides and mucopolysaccharides with sialic acid were found. In the caudal portion, neutral mucopolysaccharides and mucopolysaccharides with sialic acid were observed. Argentaffin cells were detected along the small intestine, primarily in the cranial portion. There are morphological differences, both histological and histochemical, between the cranial and caudal portion in the small intestine of C. caretta. These characteristics are correlated with possible functions in tissue physiology.

Histological and histochemical features of the small intestine in loggerhead sea turtle hatchlings (Caretta caretta)

Loggerheads ( Caretta caretta ) are endangered marine turtles and basic research is an essential component of conservation. In an attempt to provide further information in this field, we aimed to identify the microscopic morphological and histochemical features of the small intestine in the loggerhead turtle. Four loggerhead turtle hatchlings were used in this study; due to the loggerhead’s endangered status, this study was performed with dead animals. During necropsy, the cranial and caudal portions of the small intestine were obtained. The samples were embedded in paraffin and stained using the following techniques: Hematoxylin and Eosin, Gomori’s trichrome, Periodic acid-Schiff reactive (PAS), Alcian blue (pH 1.0 and pH 2.5), PAS-Alcian blue, Toluidine blue (pH 4.5 and pH 3.5), Giemsa, colloidal iron, Perl’s blue, Wilder’s impregnation, Methenamine silver, Grimelius and Masson-Fontana. The intestinal mucosa present plicae featuring a pseudostratified columnar epithelium with abundant blood vessels and abundant lymphatic vessels in the submucosa; both of these observations represent the main histological findings. The secretory granules in the goblet cells demonstrated the following characteristics: in the cranial portion, neutral mucopolysaccharides, sulfated acid mucopolysaccharides and mucopolysaccharides with sialic acid were found. In the caudal portion, neutral mucopolysaccharides and mucopolysaccharides with sialic acid were observed. Argentaffin cells were detected along the small intestine, primarily in the cranial portion. There are morphological differences, both histological and histochemical, between the cranial and caudal portion in the small intestine of C. caretta. These characteristics are correlated with possible functions in tissue physiology.

The Influence of Maternal Size on the Eggs and Hatchlings of Loggerhead Sea Turtles

Our study examined variation in and correlation of reproductive traits for a population of Caretta caretta (Loggerhead Sea Turtle) nesting in Georgia and compared the results with those of other studies. We assessed variability in reproductive traits (i.e., maternal length, clutch size, egg diameter, egg mass, hatchling length, and hatchling mass) on the population level and individual level. At the population level, we investigated interannual and intraseasonal variation of these traits for 810 Loggerhead Sea Turtle nests in Georgia, on Wassaw National Wildlife Refuge (NWR) and Blackbeard Island NWR during 2000–2003 and 2001–2003, respectively. As the nesting season progressed, we observed a decrease in clutch size, mean egg diameter, mean egg mass per clutch, mean hatchling length per clutch, and mean hatchling mass per clutch. Further, we measured all previously mentioned traits on a subset of the female turtles encountered on the beach (n = 24) and used these data to examine the variability of the traits on the individual level. Generalized linear modeling using this more refined individual-level data set indicated that 55% of the variability in clutch size was explained by a combination of maternal length (47%) and hatchling length (8%). This model suggested that clutch size was positively related with maternal length (t = 4.79) and negatively related with hatchling length (t = -1.90). Greater maternal length resulted in larger clutch size, but not larger egg size; thus, egg size was relatively constant irrespective of maternal length. These results support optimal egg-size theory, indicating a trade-off between clutch size and hatchling size to produce the optimum maternal investment per offspring.

Sun exposure, nest temperature and loggerhead turtle hatchlings: Implications for beach shading management strategies at sea turtle rookeries

Sea turtle incubation biology is tightly linked to nest thermal conditions due to the effect temperature has on hatching success, sex determination, morphology and locomotion performance. Because of this relationship between nest temperature and hatchling outcomes, global warming presents an immediate threat to many sea turtle nesting beaches throughout the world. Even small rises in nest temperatures may skew sex ratios and, raise egg mortality and influence hatchling phenotypes adversely, impacting on hatchling recruitment and ultimately species survival at some rookeries. The development of adaptive management practices capable of minimizing the effects of increasing global temperature on nest temperatures is thus a priority for animals exhibiting temperature-dependent sex-determination, such as sea turtles. Here, the relationship between solar radiation exposure and nest temperatures at the Mon Repos turtle rookery, south east Queensland, Australia was explored and the relationship between nest temperature and hatchling attributes examined. Shading decreased nest temperature, and higher nest temperatures were associated with smaller sized hatchlings that had decreased locomotion performance. The use of shading to minimize nest temperature is a management strategy that may be used to mitigate detrimental effects of increased global temperatures at some rookeries. Here, we explored the viability of natural shading options, such as the planting of trees behind nesting beaches, for combating the adverse effect of increased nest temperature caused by increased air temperatures.

Sex ratio estimations of loggerhead marine turtle hatchlings by incubation duration and nest temperature at Sirte beaches (Libya)

SUMMARY: Hatchling sex ratios in loggerhead marine turtles (Caretta caretta) were estimated on the beaches near Sirte (Libya), using two methods: incubation duration and nest mean temperature during the middle third of the incubation period. Electronic temperature/humidity loggers were deployed at a total of 13 selected nests at Al-Ghbeba, Al-Thalateen, west of Al- Thalateen, Shash and Al-Arbaeen. The incubation period ranged from 47 to 58 days and average temperature ranged from 29°C to 31.8°C. The maximum temperature during this period increased to between 0.6°C and 3.5°C, while the mean temperature also increased during the middle third of the incubation period compared with the first third and continued to increase during the last third. As expected, this study showed that the temperature in the nest decreased with increasing depth of the nest. The results showed a female-dominated sex ratio at 85.4% on the basis of incubation duration and 70.4% on the basis of mean temperature. These findings support the reported highly female-skewed sex ratios in the Mediterranean and elsewhere.

Swimming performance and metabolic rate of flatback Natator depressus and loggerhead Caretta caretta sea turtle hatchlings during the swimming frenzy

Swimming performance influences the dispersal success of sea turtle hatchlings when they first enter the water and engage in a 'swimming frenzy' which moves them rapidly offshore. We simultaneously measured swim thrust (in millinewtons, mN) and metabolic rate (in milliwatts, mW) of loggerhead Caretta caretta and flatback turtle Natator depressus hatchlings during the first 18 h of the swimming frenzy and compared the results with previous data from green turtle Chelonia mydas hatchlings. Metabolic rate was correlated with swim thrust in all species. In all species, swim thrust decreased sharply during the first 2 h of swimming, continued to slowly decrease until 12 h and remained constant at this lowest level until experiments ended at 18 h. Metabolic rate had a similar pattern, with a steep drop during the first 2 h followed by a less steep decrease before becoming relatively constant. Swim thrust and metabolic rate were highest in green turtle hatchlings. Flatback hatchling metabolic rate was similar to green turtle hatchlings but they weighed almost twice as much, while loggerhead hatchlings had the lowest metabolic rate. Flatback hatchling swim thrust decreased the fastest, falling below that of green turtle hatchlings within the first hour of swimming and falling below loggerhead turtle hatchlings after 12 h of swimming. These findings suggest that flatback hatchlings have a different dispersal behaviour compared to green and loggerhead hatchlings. The shorter highly vigorous swimming period of flatback turtles might be explained by the fact that they do not swim into off-shore oceanic dispersing currents, and managing their energy resources might be a strategic adaptation to survive predators in a relatively constant environment.

Locomotor activity during the frenzy swim: analysing early swimming behaviour in hatchling sea turtles

Swimming effort of hatchling sea turtles varies across species. In this study we analysed how swim thrust is produced in terms of power stroke rate, mean maximum thrust per power stroke and percentage of time spent power stroking throughout the first 18 h of swimming after entering the water, in both loggerhead and flatback turtle hatchlings and compared this with previous data from green turtle hatchlings. Loggerhead and green turtle hatchlings had similar power stroke rates and percentage of time spent power stroking throughout the trial, although mean maximum thrust was always significantly higher in green hatchlings, making them the most vigorous swimmers in our three-species comparison. Flatback hatchlings, however, were different from the other two species, with overall lower values in all three swimming variables. Their swimming effort dropped significantly during the first 2 h and kept decreasing significantly until the end of the trial at 18 h. These results support the hypothesis that ecological factors mould the swimming behaviour of hatchling sea turtles, with predator pressure being important in determining the strategy used to swim offshore. Loggerhead and green turtle hatchlings seem to adopt an intensely vigorous and energetically costly frenzy swim that would quickly take them offshore into the open ocean in order to reduce their exposure to near-shore aquatic predators. Flatback hatchlings, however, are restricted in geographic distribution and remain within the continental shelf region where predator pressure is probably relatively constant. For this reason, flatback hatchlings might use only part of their energy reserves during a less vigorous frenzy phase, with lower overall energy expenditure during the first day compared with loggerhead and green turtle hatchlings.

A little movement orientated to the geomagnetic field makes a big difference in strong flows

Whilst a range of animals have been shown to respond behaviourally to components of the Earth’s magnetic field, evidence of the value of this sensory perception for small animals advected by strong flows (wind/ocean currents) is equivocal. We added geomagnetic directional swimming behaviour for North Atlantic loggerhead turtle hatchlings (Caretta caretta) into a high-resolution (1/4°) global general circulation ocean model to simulate 2,925-year-long hatchling trajectories comprising 355,875 locations. A little directional swimming (1–3 h per day) had a major impact on trajectories; simulated hatchlings travelled further south into warmer water. As a result, thermal elevation of hatchling metabolic rates was estimated to be between 63.3 and 114.5% after 220 days. We show that even small animals in strong flows can benefit from geomagnetic orientation and thus the potential implications of directional swimming for other taxa may be broad.

Trans-Pacific dispersal of loggerhead turtle hatchlings inferred from numerical simulation modeling

We used Lagrangian numerical simulations to examine the trans-Pacific dispersal processes of loggerhead turtle hatchlings. Ten thousand simulated particles were released from each of the three nesting regions in Japan and tracked for 5 years. Results showed many particles moving eastward, drifting in the Kuroshio Current followed by the Kuroshio Extension Current. However, no particles reached Baja California, a known feeding area, through passive processes, indicating that trans-Pacific transportation requires active swimming by turtles. The duration of the trans-Pacific dispersal was estimated to be at least 1.6–3.4 years, with some turtles drifting in the Kuroshio Countercurrent and remaining in the western Pacific even after 5 years. This indicates that as revealed by previous genetic studies, not all loggerheads always disperse along a trans-Pacific route. The findings showed that survival and expected growth rates varied widely according to ambient temperatures during drifting, which in turn depended on nesting location.