Going back to the roots: finding a strategy for the management of nesting loggerhead sea turtles in New Caledonia

Incubation temperature plays a vital role in sea turtle life history because it influences embryonic growth, sex determination and hatchling attributes such as body size, residual yolk size, self-righting ability, crawling speed and swimming speed. For these reasons there is concern that predicted increases in air temperature, as a result of global warming, will increase nest temperatures and result in decreased hatching success, decrease or cease male hatchling production, and decreased hatchling quality. In a previous study examining incubation temperature at a loggerhead turtle (Caretta caretta) rookery located at La Roche Percée, New Caledonia, high nest temperatures and root invasion by beach morning glory (Ipomoea pes-caprae) were found to adversely affect hatching success and locomotor performance. In the current study, we relocated loggerhead turtle nests into shaded hatcheries. Shading nests decreased sand and nest temperatures and was predicted to increase male hatchling production slightly, but nest emergence success was decreased due to invasion of cottonwood (Hibiscus tiliaceus) roots into some nests. Using shaded structures is a viable and affordable management option to counteract the high sand temperatures found on some sea turtle nesting beaches, but these shade structures need to be located some distance from trees and other plants to ensure that root penetration into nests does not adversely affect nest emergence success.

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Impact of the fire ant pesticide AMDRO on loggerhead turtle nest productivity and seafinding orientation

Endangered Species Research ◽

10.3354/esr01033 ◽

2020 ◽

Vol 41 ◽

pp. 339-347

Author(s):

HE Smith ◽

SR Hoover ◽

M Salmon ◽

H Seaman ◽

CM Coppenrath ◽

...

Keyword(s):

Nest Site ◽

Hatching Success ◽

Loggerhead Turtle ◽

Sea Turtle ◽

Fire Ants ◽

Fire Ant ◽

Typical Application ◽

Ghost Crabs ◽

Emergence Success ◽

Nesting Beaches

Invasive fire ants prey on a variety of organisms in the southeastern USA, including the pipped eggs and hatchlings within sea turtle nests. The granular fire ant bait AMDRO® (active ingredient hydramethylnon) is currently used at some rookeries to protect nests, but no studies have been conducted to determine if the pesticide negatively impacts the eggs or the hatchlings. We examined the pesticide’s effect on loggerhead (Caretta caretta) nests at Juno Beach, Florida, USA, specifically targeting how exposure affected hatching success, hatchling emergence success, and the ability of the turtles to orient visually from the nest to the sea. Pesticide granules were placed within a 30 cm diameter circle on the sand directly above the nest during the final 5-10 days of incubation, representative of its typical application at nesting beaches. Cornmeal granules in soybean oil and untreated natural nests served as controls. AMDRO had no significant effect on hatching success or emergence success, nor did it result in any deficiencies in hatchling orientation accuracy. However, the pesticide and cornmeal control attracted other predators (Atlantic ghost crabs and avian species), in addition to fire ants, to the nest site, thus revealing the nest’s location and potentially increasing its vulnerability. Consequently, we suggest that its usage may not be beneficial at sites where predators other than ants are especially abundant.

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Effect of nest temperature on hatchling phenotype of loggerhead turtles (Caretta caretta) from two South Pacific rookeries, Mon Repos and La Roche Percée

Australian Journal of Zoology ◽

10.1071/zo12079 ◽

2012 ◽

Vol 60 (6) ◽

pp. 402 ◽

Cited By ~ 25

Author(s):

Tyffen Read ◽

David T. Booth ◽

Colin J. Limpus

Keyword(s):

Thermal Tolerance ◽

Hatching Success ◽

New Caledonia ◽

Loggerhead Turtle ◽

Caretta Caretta ◽

Nest Temperature ◽

Genetic Stock ◽

Upper Limit ◽

Emergence Success ◽

The Mean

La Roche Percée, in New Caledonia, is the most important loggerhead turtle rookery outside of Australia for the eastern Pacific genetic stock. The females nesting on this beach are genetically similar to the females found at the Mon Repos rookery in Queensland, Australia. This study shows how nest temperature affects the phenotype of genetically similar populations. During the 2010–11 breeding season, mean nest temperatures were significantly higher at La Roche Percée (31.8°C) than at Mon Repos (29.5°C) and the mean for the three-days-in-a-row maximum nest temperatures was also significantly higher at La Roche Percée (34.6°C), than at Mon Repos (31.7°C). Differences were found in mean hatching success (La Roche Percée 83 ± 3%, Mon Repos 96 ± 2%) and emergence success (La Roche Percée 76 ± 3%, Mon Repos 93 ± 3%). Hatchlings from La Roche Percée also had significantly lower fitness characteristics, having smaller carapace size (La Roche Percée 1565 ± 7 mm2, Mon Repos 1634 ± 5 mm2), slower self-righting times (La Roche Percée 4.7 ± 0.1 s, Mon Repos 2.7 ± 0.1 s) and slower crawling speed in terms of both absolute speed and body lengths per second (La Roche Percée 2.5 ± 0.2 cm s–1 or 0.57 ± 0.05 body lengths s–1, Mon Repos 4.6 ± 0.1 cm s–1 or 1.04 ± 0.02 body lengths s–1). Nest temperatures at La Roche Percée approached the upper limit of embryo thermal tolerance towards the end of incubation (34°C) and this condition may contribute to the lower hatching and emergence success and lower fitness characteristics of hatchlings at the La Roche Percée rookery.

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Incubation temperatures, hatching success and congenital anomalies in green turtle nests from Guanahacabibes Peninsula, Cuba

AQUATIC RESEARCH ◽

10.3153/ar21027 ◽

2021 ◽

Vol 4 (4) ◽

pp. 321-330

Author(s):

Randy Calderón Peña ◽

Julia Azanza Ricardo

Keyword(s):

Congenital Anomalies ◽

Green Turtle ◽

Thermal Tolerance ◽

Elevated Temperatures ◽

Hatching Success ◽

Incubation Temperature ◽

Chelonia Mydas ◽

Sea Turtle ◽

Green Turtles ◽

Incubation Temperatures

Elevated incubation temperatures of sea turtle nests decrease hatching success and alter the resulting hatchlings' morphology. There is an absence of studies assessing the relationships between temperature and hatching success in Cuba, even when they could improve understanding the limits of thermal tolerance in these species. This study evaluated the influence of incubation temperature on hatching success and phenotypic malformations in green turtle hatchlings (Chelonia mydas); and analyzed the temporal variation in hatching success on the studied beaches. In 48 green turtles nests distributed along two beaches, incubation temperature and hatching success were recorded between 2014 and 2019. Increasing incubation temperature caused a decrease in the hatching success and an increase in the frequency of supernumerary scutes. Despite the elevated temperatures (average > 30°C), hatching was higher than 80%. Significant differences in hatching success were only observed among seasons for nests in Antonio Beach (lower values in 2016 and 2019 compared to 2014).

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Nesting activity of the Loggerhead sea turtle, Caretta caretta, in Calabria: 2016-2020 reproductive seasons

Mediterranean Marine Science ◽

10.12681/mms.26085 ◽

2021 ◽

Author(s):

MARIA DENARO ◽

TERESA MALITO ◽

CARMELA MANCUSO ◽

GIOVANNI PARISE ◽

SALVATORE URSO

Keyword(s):

New Technologies ◽

Survey Methods ◽

Loggerhead Turtle ◽

Sea Turtle ◽

Success Rates ◽

Monitoring Method ◽

Loggerhead Sea Turtle ◽

Emergence Success ◽

The Mean ◽

Nesting Activity

The nesting activity of the loggerhead turtle along the coast of Calabria during five reproductive seasons (2016-2020) is presented. From May to August, survey methods were conducted using traditional observations on foot and utilizing additional innovative technologies, including electric fat bikes and drones. Monitoring was intensively focused on a key nesting area of approximately 40 km located on the southernmost Ionian coast of Reggio Calabria, and, for only the 2020 season, the area was extended an additional 40 km northeast. In the five nesting seasons, 419 female emergences were recorded, 192 of which were classified as nests. Overall, 65.1% (n = 125) of nests were found along the area regularly monitored in all nesting seasons. The maximum nesting activity was observed during July, and the mean nesting success was 45.8%. The average number of eggs for all seasons was 92.2 (n = 163; S.D.: ± 21.1; range: 39-160). The mean hatching and emergence success rates were 70.8% and 62.5%, respectively. The mean incubation period was 49 days (n = 122; S.D.: ± 5.4; range: 42-82). Considering previous data from the same area, our study shows an actual increase in nesting activity, probably due to the implementation of an effective monitoring method that includes the use of new technologies, which made it possible to expand the regularly monitored area, and a greater awareness campaign in recent years. Regarding the reproductive parameters, our data is similar to that reported for other Mediterranean nesting grounds.

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Low male production at the world’s largest green turtle rookery

Marine Ecology Progress Series ◽

10.3354/meps13500 ◽

2020 ◽

Vol 653 ◽

pp. 181-190

Author(s):

DT Booth ◽

A Dunstan ◽

I Bell ◽

R Reina ◽

J Tedeschi

Keyword(s):

Green Turtle ◽

Hatching Success ◽

Incubation Temperature ◽

Chelonia Mydas ◽

Sea Turtle ◽

Green Turtles ◽

Nesting Site ◽

Almost All ◽

Monthly Variations ◽

Nesting Season

Because the sex of all sea turtle hatchlings is determined by incubation temperature, with low temperatures producing mainly males and high temperatures producing mainly females, sea turtle populations worldwide are threatened by feminization of hatchlings due to increases in global temperature. Data obtained by laparoscopic sexing of immature individuals captured from a major feeding ground indicates that over several decades there has been little recruitment of males into the northern Great Barrier Reef (nGBR) green turtle Chelonia mydas population, one of the largest sea turtle populations in the world. Over 2 nesting seasons, we measured nest temperatures at Raine Island, the most important nesting site for this nGBR population, and predicted that almost all nests would have produced all female hatchlings. The few nests that produced some male hatchlings were constructed at the very end of the nesting season, and these nests had the lowest hatching success. Taking into account monthly variations in nest construction, hatching success, and hatchling sex ratio, we estimate that over an entire nesting season only 0.7% of hatchlings produced are male. Hence, we conclude that the nGBR population of green turtles has likely recruited very few males in recent years.

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Globally important refuge for the loggerhead sea turtle: Maio Island, Cabo Verde

Oryx ◽

10.1017/s0030605320001180 ◽

2021 ◽

pp. 1-9

Author(s):

Juan Patino-Martinez ◽

Leno Dos Passos ◽

Inês O. Afonso ◽

Arnau Teixidor ◽

Manjula Tiwari ◽

...

Keyword(s):

Management Strategy ◽

Hatching Success ◽

Management Strategies ◽

Loggerhead Turtle ◽

Sea Turtle ◽

Sandy Beaches ◽

Loggerhead Sea Turtle ◽

Artificial Lighting ◽

Cabo Verde ◽

Comprehensive Study

Abstract One of the largest nesting colonies of the Vulnerable loggerhead sea turtle Caretta caretta is in Cabo Verde. Here we present the first comprehensive study of loggerhead turtle nesting on the island of Maio in Cabo Verde. During 2016–2019 we monitored 38 km of undeveloped sandy beaches that have minimal artificial lighting and where all nesting on Maio takes place. We counted 4,063 nests in 2016, 5,429 in 2017, 14,364 in 2018 and 7,937 in 2019. The estimated total number of females was 1,016, 1,357, 3,591 and 1,984 in each of these years, respectively. Our findings suggest there are more loggerhead turtles nesting in Cabo Verde than previously estimated, and that this could be the species’ largest nesting subpopulation (followed by Florida, USA and Oman). The inter-annual hatching success (the proportion of eggs producing hatchlings) was 29–38% for the whole island but varied between sites. Our study of 250 clutches showed that flooding affected 38–61% and predation by crabs 40–42%, with hatching success on different beaches in the range of 1–59%. Poaching of eggs was rare (< 2% of clutches), but dogs predated 68.4% of all clutches on the beach nearest the largest human settlement. We evaluated different nest management strategies at multiple sites and estimated productivity of hatchlings (the number of hatchlings that would reach the sea for each management strategy), finding that hatcheries are not always the best option for nest management. As the beaches on Maio are relatively undisturbed, and there is a high abundance and density of turtle nests, the island should be protected as a globally important site for the conservation of the loggerhead turtle, and of coastal biodiversity more broadly.

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

Wildlife Research ◽

10.1071/wr15138 ◽

2016 ◽

Vol 43 (1) ◽

pp. 27 ◽

Cited By ~ 2

Author(s):

Katharine Robertson ◽

David T. Booth ◽

Colin J. Limpus

Keyword(s):

Red Light ◽

Loggerhead Turtle ◽

Sea Turtle ◽

Eastern Coast ◽

Loggerhead Sea Turtles ◽

Cumulative Impact ◽

Artificial Lighting ◽

Light Peak ◽

Peak Intensity ◽

Red Led

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.

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The effect of the predicted air temperature change on incubation temperature, incubation duration, sex ratio and hatching success of loggerhead turtles

Animal Biology ◽

10.1163/157075511x596864 ◽

2011 ◽

Vol 61 (4) ◽

pp. 369-383 ◽

Cited By ~ 4

Author(s):

Salih Hakan Durmuş ◽

Çetin Ilgaz ◽

Özgür Güçlü ◽

Adem Özdemir

Keyword(s):

Sex Ratio ◽

Temperature Change ◽

Air Temperature ◽

Hatching Success ◽

Incubation Temperature ◽

Loggerhead Turtle ◽

Temperature Changes ◽

Air Temperatures ◽

Nesting Sites ◽

Incubation Duration

AbstractMarine turtles are sensitive to temperature changes and thus are likely to be impacted by the predicted climate change. This study assesses the effect of the predicted air temperature change on incubation temperature, incubation duration, sex ratio and hatching success of the loggerhead turtle Caretta caretta at the Mediterranean nesting sites of Dalyan and Fethiye, Turkey. We recorded sand temperatures and used air temperatures at two nesting sites to estimate the sex ratio of hatchlings. The data showed that hatchling production was 59.1% and 77.7% at Dalyan in 2004 and 2009, respectively, and 72.2% and 72.3% at Fethiye at 2008 and 2009, respectively. Incubation temperature was positively correlated with both air temperature and distance to sea. Sex ratio estimation and incubation duration between the years 1993 and 2009 in Fethiye show polynomic trend lines. The best predictors of hatching success were distance to vegetation and wet depth of nest. We modelled the effects of incremental increases in the future air temperature of up to 10°C. We suggest that clutch death is not likely to begin until 3°C of warming, increasing from 5.3% to 100.0% with warming between 4°C and 10°C.

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Population model analysis for the loggerhead sea turtle, Caretta caretta, in Queensland

Wildlife Research ◽

10.1071/wr9960143 ◽

1996 ◽

Vol 23 (2) ◽

pp. 143 ◽

Cited By ~ 52

Author(s):

SS Heppel ◽

CJ Limpus ◽

DT Crouse ◽

NB Frazer ◽

LB Crowder

Keyword(s):

Population Decline ◽

Survival Rates ◽

Loggerhead Turtle ◽

Caretta Caretta ◽

Sea Turtle ◽

Marine Turtle ◽

Emergence Success ◽

Eastern Australia ◽

Loggerhead Turtles ◽

The Usa

Worldwide declines of marine turtle populations have forced a need for sound conservation policies to prevent their extinction. Loggerhead turtles, Caretta caretta, are declining rapidly at eastern Australian nesting beaches, which are visited by females from all feeding areas for the stock. In some feeding areas of eastern Australia, loggerheads have been protected from deleterious anthropogenic effects. Using long-term mark-recapture data from one such protected group of turtles feeding on Heron Island Reef, Queensland, we created a matrix model to analyse loggerhead demography. We also produced a model for the females nesting at Mon Repos, Queensland, a major rookery where the annual nesting population has declined at rates approaching 8% per year. As indicated by a similar model for loggerheads in the USA, our models predicted that small declines in annual survival rates of adult and subadult loggerheads can have a profound impact on population dynamics. A loss of only a few hundred subadult and adult females each year could lead to extinction of the eastern Australian loggerheads in less than a century. Survival in the first year of life is relatively less important in these long-lived and slow-maturing animals. At Mon Repos, nesting female survival is apparently so low that even beach protection efforts resulting in 90% hatchling emergence success would not prevent population decline. Our research suggests that continued mortality pressure on subadult and adult turtles in their dispersed feeding areas of eastern and northern Australia is a major threat to the eastern Australian loggerhead turtle population. Measures that protect adult and subadult loggerhead turtles should be supported, including the use of turtle excluder devices (TEDs) on prawn trawls.

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The Effect of Invertebrate Infestation on Green Turtle (Chelonia mydas) Nests on Kazanlı Beach, Mersın, Turkey

Russian Journal of Herpetology ◽

10.30906/1026-2296-2020-27-5-245-256 ◽

2020 ◽

Vol 27 (5) ◽

pp. 245-256

Author(s):

Cemil Aymak ◽

Aşkın Hasan Uçar ◽

Yusuf Katılmış ◽

Eyup Başkale ◽

Serap Ergene

Keyword(s):

Green Turtle ◽

Hatching Success ◽

Negative Relationship ◽

Chelonia Mydas ◽

Sea Turtle ◽

Faunal Composition ◽

Independent Variables ◽

Invertebrate Species ◽

First Time ◽

Nesting Season

In this study invertebrate infestation in green turtle (Chelonia mydas) nests were recorded for the first time for Kazanlı beach, Mersin, Turkey. For this aim, in 2006 nesting season, 294 natural intact green turtle nests were sampled to examine their contents and invertebrate infestation was found in 76 (25.85% of the total sampling green turtle nests). These infested nests were examined in terms of the invertebrate faunal composition. The specimens found in the green sea turtle nests were identified to order, family or genus levels and they were represented in 5 orders. These invertebrate groups are Elater sp. larvae (Elateridae; Coleoptera), Pimelia sp. larvae (Tenebrionidae; Coleoptera), Enchytraeidae (Oligochaeta), Cyrptostigmata (Acari), Oniscidae (Isopoda), Formicidae (Hymenoptera). Elater sp. was the most common invertebrate group in the green turtle nests. According to student t test, we found statistically significant differences between 7 independent variables and invertebrate species presence. Furthermore, logistic regression analysis explained that there is a negative relationship between hatching success rate and invertebrate species presence.

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