Loggerhead Sea Turtle Eggs Research Articles

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.

Flooding-induced mortality of loggerhead sea turtle eggs

Abstract ContextMarine turtle eggs incubate in dynamic beaches, where they are vulnerable to both saltwater and freshwater flooding. Understanding the capacity for marine turtle eggs to tolerate flooding will aid management efforts to predict and mitigate the impacts of climate change, including sea-level rise and increases in coastal flooding. AimsEvaluate the interactive effects of flooding duration and incubation stage on the hatching success of loggerhead turtle (Caretta caretta) eggs. MethodsGroups of 20 eggs from multiple clutches were incubated in plastic containers in a beach hatchery. Eggs at six stages of incubation (0, 1, 2, 4, 6 and 7 weeks post-oviposition) were excavated from the hatchery and exposed to saltwater or freshwater flooding for seven durations of time (0, 1, 2, 3, 6, 24 or 48h). Containers of eggs were either submerged in a bucket of water or left outside of the bucket (control; no flooding) for their designated duration, allowed to drain, then reburied in the hatchery. Following hatchling emergence, the hatching success of each group of eggs was evaluated. Key resultsFreshly laid eggs and eggs on the verge of hatching exposed to any flooding and all eggs exposed to extended periods of flooding (24 and 48h) suffered complete mortality. Eggs at 20–80% development exposed to short periods of flooding (1–6h) maintained high hatching success that was statistically equivalent to control eggs, while eggs at <20% and >80% development exhibited significant decreases in hatching success. ConclusionsMarine turtle eggs in the middle of incubation can tolerate saltwater and freshwater flooding for up to 6h. Outside of this period or when flooding is longer, disruption of gas concentrations and osmotic gradients in the egg chamber can lead to embryonic mortality. These findings have reinforced concerns regarding the capacity for marine turtle populations to continue to function as rising sea levels and increases in coastal flooding alter the hydrology of nesting beaches. ImplicationsAs current and predicted climate change threatens the suitability of the incubation environment used by marine turtles, corrective actions to maximise hatching success need to be taken before the eggs are flooded.

Predation of loggerhead sea turtle eggs across Georgia’s barrier islands

Nesting beach management is a vital element of the population recovery efforts for the vulnerable loggerhead sea turtle (Caretta caretta) across the globe. In the southeast United Sates, turtle nests are threatened by numerous anthropogenic and natural threats, including predation of eggs by native and non-native predators. We analyzed loggerhead nest predation and other egg; loss using an exceptional 10-year data set (2009–2018) that covered nesting beaches on 12 islands on the Georgia coast. Our objectives were to 1) determine which predators cause the greatest loss of loggerhead sea turtle eggs, 2) evaluate whether non-native species have a higher; rate of predation than native species, and 3) compare predation rates to other major sources of egg loss across these islands. Our results show that under current strategies for nest management: 1) non-native feral hogs and native raccoons have the greatest impact as predators on sea turtle eggs; 2) non-native predators have caused significantly more egg loss across Georgia’s coast than native species, but the impact varies greatly by species; and 3) losses to predation are similar in magnitude to post-management losses from tides and storms over the last decade. We recommend the continued use of multiple management techniques, including nest screening and; targeted predator management, but caution that predator controls should be focused on those demonstrated to cause significant losses in order to prioritize conservation funding.

Nesting activity of sea turtles, Caretta caretta (Linnaeus, 1758) and Chelonia mydas (Linnaeus, 1758) (Reptilia, Cheloniidae), at Patara Beach (Antalya, Turkey) over four nesting seasons

Patara Beach is one of the most important nesting beaches in Turkey for Caretta caretta. In this paper, we provide information on the nesting activity, spatial and temporal distribution of nesting, nesting and hatching success, nesting density, incubation duration, clutch size, and predation ratio of sea turtles over four nesting periods, namely 2010, 2012, 2013, and 2014. An average of 179.75 nests were recorded per year, and the overall nesting density was 15.50 nests/km while 68.20 loggerhead sea turtle eggs were recorded per nest. The hatching success was 44.05% from these counted eggs and 38.04% of hatchlings were able to reach the sea. We also observed 3 Chelonia mydas nests. The highest nesting activity during our monitoring over the past 20 years was obtained in 2013. The average annual number of turtle nests in Patara over 20 nesting seasons was 94.70.

Mid-incubation relocation and embryonic survival in loggerhead sea turtle eggs

Relocations of sea turtle nests are generally performed within 12 hours of deposition to avoid damaging fragile respiratory membranes as they attach to the egg. In May 2007, a tropical storm on the east coast of Florida resulted in severe dune erosion and permission was given for beach and dune restoration. Nests already located on the beach, or that were laid prior to project commencement, were relocated at times varying between 10 days and 38 days post-deposition. This provided an opportunity to examine egg mortality in loggerhead sea turtle (Caretta caretta) nests moved during this critical time period, and determine whether there was a correlation between the relocation and the timing of arrested egg development; we compared hatching and emergence success to nests relocated during the standard initial 12 hours post-deposition and those left in situ. Following hatchling emergence, we collected remaining unhatched eggs to determine development stage at the time of embryonic death. Mean hatch success was 53% for nests moved mid-incubation, versus 79–90% for nests left in situ or moved within 12 hours of deposition. For 6 of 10 nests, embryonic development ceased at the same visual developmental stage as the relocation. Although moving nests later than 12 hours decreases nest success and should be a matter of last resort, the forecasts for increased storm activity and sea level rise, and other impacts such as beach oiling, may necessitate nest relocation under less than ideal circumstances. Choice of relocation site may also be significant; nests placed in native sand had lower emergence success than those moved to the renourished area. © 2015 The Wildlife Society.

Effects of Beach Renourishment and Clutch Relocation on the Success of the Loggerhead Sea Turtle (Caretta caretta) Eggs and Hatchlings

Along the coasts of Florida, beach erosion caused by large storms and hurricanes coincides with the nesting season of the Loggerhead Sea Turtle. Here, we report the effects of beach renourishment and nest relocation on the success of Loggerhead Sea Turtle (Caretta caretta) eggs and hatchlings. Data on ∼53,700 Loggerhead Sea Turtle eggs from 517 clutches were collected over a six-year period, 2006 through 2011, on the Gulf Coast beaches of Pinellas County, Florida. We compared the proportion of eggs that hatched and hatchlings that emerged based on relocation; the type of beach on which breeders deposited their eggs (natural or renourished), and the type of beach to which clutches were relocated (natural or renourished). In this study, beach renourishment had no adverse effect on the proportion of eggs that hatched or the proportion of hatchlings that emerged. In contrast, clutch relocation decreased the proportion of inundated clutches 10-fold from 28–3%; an important finding as water inundation destroyed nearly half of the eggs per clutch. These findings add to a growing body of research on beach renourishment and clutch relocation with important implications for the continued management of Loggerhead Sea Turtle nests.

Forty‐seven days of decay does not change persistent organic pollutant levels in loggerhead sea turtle eggs

Reptile and bird eggs are priority samples for specimen banking programs that assess spatial and temporal trends of environmental contaminants. From endangered species, such as sea turtles, nonlethal sampling is required (e.g., unhatched eggs collected postemergence). Previous contaminant monitoring studies have used unhatched sea turtle eggs, but no study has tested whether their concentrations represent levels found in fresh eggs (e.g., eggs collected within 24 h of oviposition). The author analyzed three fresh eggs from different nest depths and up to three unhatched eggs from 10 loggerhead sea turtle (Caretta caretta) nests in South Carolina, USA, for a suite of persistent organic pollutants (POPs). Lipid-normalized POP concentrations were not significantly different (p > 0.05) between fresh and unhatched eggs or among different depths from the same nest. The POP concentrations in loggerhead eggs from South Carolina were higher than previously measured concentrations in eggs from Florida and slightly lower than concentrations in eggs from North Carolina. This pattern agrees with previously observed trends of increasing POP concentrations in loggerhead turtles inhabiting northern latitudes along the U.S. East Coast. Contaminant profiles are discussed, including a higher chlorinated pattern of polychlorinated biphenyls possibly associated with a Superfund site in nearby Brunswick, Georgia, USA, and unusual polybrominated diphenylether patterns seen in this and previous sea turtle studies. Concentrations correlated with one of eight measurements of reproductive success; levels were negatively correlated with egg mass (p < 0.05), which may have implications for hatchling fitness. The present study suggests that unhatched eggs can be used for POP-monitoring projects.

Incubation temperature and energy expenditure during development in loggerhead sea turtle embryos

The choice of a suitable nest habitat by oviparous reptiles that deposit eggs into a nest and provide no subsequent parental care is likely to play a major role in the survival of the offspring. In particular variations in nest temperature may influence the rate at which embryos utilise their yolk energy. The effects of nest temperature on total energy use are however complex. High temperatures may advance development and shorten the time to hatching, thereby reducing energy use, but they also stimulate metabolic rate increasing energy use. The net effect of temperature on total energy demands is therefore uncertain. Oxygen consumption (VO 2) and carbon dioxide production (VCO 2) were measured by open-flow respirometry during the incubation of loggerhead sea turtle eggs at three temperatures (27.6, 30.0 and 31.8 °C). At each temperature, VO 2 and VCO 2 showed a peak followed by a decline to hatching. Incubation temperature was negatively related to incubation duration and positively related to the maximum metabolic rate of the embryos. Peak VO 2 was 74.8 ml/egg/day at 27.6 °C, 91.9 ml/egg/day at 30.0 °C, and 97.9 ml/egg/day at 31.8 °C. Peak VO 2 occurred closer to hatching in eggs incubated at higher temperatures. Total energy expenditure was greatest at the lowest incubation temperature and lowest at the highest temperature. Total VO 2 and VCO 2 were 1777 ml/egg and 1226 ml/egg, respectively, at 27.6 °C, 1680 ml/egg and 1235 ml/egg at 30.0 °C, and 1613 ml/egg and 1191 ml/egg at 31.8 °C. Using the actual RQ values, this corresponds to a cost of development of 34,963 J/egg at 27.6 °C, 33,403 J/egg at 30.0 °C, and 32,107 J/egg at 31.8 °C. At all temperatures, the calculated respiratory quotient values did not suggest that yolk substrates were oxidised proportionately, but more likely indicated their sequential use. Nest temperatures may play a key role in energy use, with cooler temperature nests increasing the overall energy demands placed on developing embryos.

Comparison of biochemical and molecular methods for the identification of bacterial isolates associated with failed loggerhead sea turtle eggs

Comparison of biochemical vs molecular methods for identification of microbial populations associated with failed loggerhead turtle eggs. Two biochemical (API and Microgen) and one molecular methods (16s rRNA analysis) were compared in the areas of cost, identification, corroboration of data with other methods, ease of use, resources and software. The molecular method was costly and identified only 66% of the isolates tested compared with 74% for API. A 74% discrepancy in identifications occurred between API and 16s rRNA analysis. The two biochemical methods were comparable in cost, but Microgen was easier to use and yielded the lowest discrepancy among identifications (29%) when compared with both API 20 enteric (API 20E) and API 20 nonenteric (API 20NE) combined. A comparison of API 20E and API 20NE indicated an 83% discrepancy between the two methods. The Microgen identification system appears to be better suited than API or 16s rRNA analysis for identification of environmental isolates associated with failed loggerhead eggs. Most identification methods are not intended for use with environmental isolates. A comparison of identification systems would provide better options for identifying environmental bacteria for ecological studies.

The ultrastructure of sea turtle eggshell does not contribute to interspecies variation in fungal invasion of the egg

The eggshells of green ( Chelonia mydas (L., 1758)), loggerhead (Caretta caretta (L., 1758)), hawksbill ( Eretmochelys imbricata (L., 1766)), and flatback ( Natator depressus (Garman, 1880)) sea turtles nesting in eastern Australia were examined by scanning electron microscopy to determine if the ultrastructure was contributing to interspecific variation in fungal invasion of eggs. The eggshells of all species investigated were of similar structure (outer inorganic layer of aragonite crystals and an inner organic fibrillar layer) and of similar thickness. Well-defined pores that would allow direct entry of fungal hyphae or spores were not present in any species. It was concluded that the eggshell ultrastructure does not allow direct access by fungal hyphae or spores and does not contribute to interspecific variation in the vulnerability of loggerhead sea turtle eggs to fungal infection.

Organochlorine, PCB, PAH, and metal concentrations in eggs of loggerhead sea turtles (Caretta caretta) from northwest Florida, USA

Composite samples of unhatched and physically unaltered loggerhead sea turtle, Caretta caretta, eggs collected from 20 nests along northwest Florida were analyzed for organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and metals. Chemical analyses revealed that turtle eggs contained detectable amounts of metals, PAHs, and PCBs. Only one OCP, p, p'‐DDD, was detected, and its presence was restricted to eggs from two nesting sites. None of the PCB concentrations exceeded the Food and Drug Administration's (FDA) action limit. Concentrations of dioxin‐like PCB congeners, 105, 118, and 126, and total PCBs were also detected and are contributors to the toxic burden of loggerhead sea turtle eggs. Concentrations of PAHs, 1,2,5,6‐dibenzanthracene, 1‐methyl naphthalene, Cl‐naphthalene and naphthalene were variable at nesting sites. Comparison of mean metal burdens in eggs from different beaches suggested that no uniform geographic gradients exist. Presence of OCPs, PCBs, PAHs and metals and their additive or synergistic toxicity is a concern to loggerhead sea turtle eggs; however, additive or synergistic impacts for loggerhead sea turtles are largely undocumented.

DDE residues and artificial incubation of loggerhead sea turtle eggs.

DDE residues and artificial incubation of loggerhead sea turtle eggs.

Heavy Metals in Loggerhead Sea Turtle Eggs (Caretta caretta): Evidence to Support the Hypothesis That Demes Exist in the Western Atlantic Population

Concentrations of thirteen heavy metals in Loggerhead sea turtle eggs, collected from four nesting beaches, were determined. Comparisons of mean heavy metal burdens in eggs from different beaches suggested that no uniform geographic gradients exist in the nesting population. The comparisons did indicate that eggs laid on each beach had significantly different mean concentrations of barium, cobalt, chromium, mercury, molybdenum, nickel and lead. These data suggest the presence of groups of turtles and indirectly support the hypothesis that the Western Atlantic Loggerhead pcpulation is composed of demes.