Pengaruh Kedalaman Sarang Terhadap Daya Tetas Telur Penyu Lekang (Lepidochelys olivacea Escholtz, 1829) di Kawasan Penangkaran Penyu Kota Pariaman

This study aims to determine the hatchability of Olive Ridley Sea Turtle eggs at different nest depths. This is an experimental research that used a Completely Randomized Design (CRD) with four nest depths P1:30 cm, P2:40 cm, P3:50 cm, P4:60 cm and 4 repetition with each nest filled with 10 eggs. Environmental nest temperatureair and air humidity were measured during the incubation period. The number of hatched eggs collected on day 60 incubation or when the moment hatchlings reveal at nest surface. Data collected after 60 days incubation as the average percentage of hatched eggs and test by ANOVA, with Duncan New Multiple Range Test (DNMRT). The result showed the average of percentage hatchability P1 92.5%, P2 90.0%, P3 82.5% and P4 60%. Based on statistical analysis the P1, P2, and P3 increased hatchability significantly higher (p<0,05) compared to P4. From the results studied it can be concluded that the nest depth has influenced egg hatchability of Olive Ridley Sea Turtle in Turtle Breeding of Pariaman City.

Penetasan telur penyu sisik (Eretmochelys imbricata) dengan kedalaman yang berbeda

This research was conducted from November 2018 until January 2019 which was held at the UPTD Conservation and Supervision of Marine Resources and Fisheries in West Sumatera, Pariaman City. The aim of the research is to know hatchling hawksbill sea turtle eggs based on nest depth. The method used in this study is a nonfactorial randomized block design (RBD) consisting of 3 treatments and 3 replications. The treatments used were treatment A (with a depth of 30 cm incubation nest), treatment B (with a depth of incubation nest 40 cm), and Treatment C (with a depth of incubation nest 50 cm). The results of this study showed that hatching hawksbill eggs hatched very significantly, the best hatching percentage was in treatment A (30cm) with 78% hatching at 6:00 a.m. with hatching temperature range of 24-28oC, hatching pH of 6,6-6,8 and medium sized incubation sand with a size of 0.150 mm with a weight reaching 461 grams.Keywords: Hatching percentage, Hawksbill turtle, pH, Temperature

Neonatal biometry and characterization of Amazonian Turtle nests (Podocnemis expansa)

The present study aimed to study the reproduction of the Amazon turtle (Podocnemis expansa) through the evaluation of the reproductive parameters of adult females. This study was carried out in the Crixás-Açu River, municipality of Mundo Novo, state of Goiás, Brazil. In September, the biometrics of 20 females were evaluated during the spawning period. Their nests were marked for subsequent evaluation of hatchlings, measuring the distances of each nest to the river and vegetation. The second stage consisted of the evaluation of hatchlings and characterization of nests after egg hatching. The data were tested using the Pearson Correlation to measure the degree of linear correlation between the variables analyzed, such as the parameters of females, hatchlings, nests, and eggs. Nest depth was positively correlated with the number of eggshells found. We also found a correlation between the number of eggsshells and the distance of nests to the vegetation. Although moderate, this result indicates that as the distance to the vegetation increases, the number of eggshells found in nests decreases. The spawning site for Amazon turtle breeding is crucial to determine a higher number of eggs hatching and better development of hatchlings. However, the literature is still very scarce regarding the choice of spawning grounds and the influence that vegetation may have on the development of freshwater turtle hatchlings in Brazil.

Effectiveness of Sea Turtle Conservation Management at the Turtle Conservation and Education Center of Serangan, Denpasar Bali

Turtles are one of the reptile animals that can migrate long distances along the Indian Ocean, Pacific Ocean and Southeast Asia. The purpose of turtle migration is to mate, find spawning locations and to find food. Sea turtles have an important role in maintaining the balance of the marine ecosystem. However, the high utilization of sea turtles by humans causes the turtle population to decline. One of the conservation sites that help the government program is in Serangan, Denpasar Bali, namely the TCEC (Turtle Conservation and Education Center), where there are several types of turtles such as the lekang turtle, hawksbill and green turtle. Data collection techniques in this study used observation methods including beach monitoring, relocation of turtle eggs to semi-natural hatchery hatching, hatchling and turtle nesting as well as measurement of turtle length and width carapase curve (CCL/CCW), sand temperature, nest depth, nest diameter, nest distance and nest calculation of the number of eggs to see the success of hatching. The results are turtle conservation activities, ranging from turtle maintenance, hatching of turtle eggs, relocation of eggs, and maintenance of hatchlings to release turtles. The effectiveness given by TCEC to manage and preserve the existence of sea turtles in Indonesia, especially in the Bali region is to provide awareness to the community by not consuming eggs and turtle meat.

Nest Architecture and Colony Growth of Atta bisphaerica Grass-Cutting Ants

Atta grass-cutting ants (Formicidae: Myrmicinae: Attini) are found in the Cerrado biome and build giant nests with hundreds or thousands of large chambers. We assessed for Atta bisphaerica grass-cutting ants whether the total volume of fungus chambers and other nest parameters grow at close or similar proportions to worker numbers in the colony. Data on fungus garden biomass, population, external area, number of entrance holes, number of fungus chambers, total fungus chambers volume, and nest depth were obtained during colony growth/nest development. Our results reveal that the fungus garden biomass, external area, and total fungus chamber volume increased at rates similar to the increase in the number of workers. The total volume of chambers, and external area increased at a similar proportion to the increase in number of workers, probably due to the fungus garden allocation needs of the colony. The number of fungus chambers, number of entrance holes, and nest depth increased less than 4-fold for every 10-fold increase in the worker number. In addition, the height of the fungus chambers increased as the width increased, a pattern not observed for tunnel height and length, and the chamber volume increased according to worker number. Thus, this study demonstrates for A. bisphaerica that nest development in terms of chamber volume is similar to the increase in number of colony workers, and this contributes to a better understanding of Atta nest architecture.

Plasticity in nest site choice behavior in response to hydric conditions in a reptile

Natural selection is expected to select for and maintain maternal behaviors associated with choosing a nest site that promotes successful hatching of offspring, especially in animals that do not exhibit parental care such as reptiles. In contrast to temperature effects, we know little about how soil moisture contributes to successful hatching and particularly how it shapes nest site choice behavior in nature. The recent revelation of exceptionally deep nesting in lizards under extreme dry conditions underscored the potential for the hydric environment in shaping the evolution of nest site choice. But if deep nesting is an adaptation to dry conditions, is there a plastic component such that mothers would excavate deeper nests in drier years? We tested this hypothesis by excavating communal warrens of a large, deep-nesting monitor lizard (Varanus panoptes), taking advantage of four wet seasons with contrasting rainfall amounts. We found 75 nests during two excavations, including 45 nests after a 4-year period with larger wet season rainfall and 30 nests after a 4-year period with smaller wet season rainfall. Mothers nested significantly deeper in years associated with drier nesting seasons, a finding best explained as a plastic response to soil moisture, because differences in both the mean and variance in soil temperatures between 1 and 4 m deep are negligible. Our data are novel for reptiles in demonstrating plasticity in maternal behavior in response to hydric conditions during the time of nesting. The absence of evidence for other ground-nesting reptile mothers adjusting nest depth in response to a hydric-depth gradient is likely due to the tradeoff between moisture and temperature with changing depth; most ground-nesting reptile eggs are deposited at depths of ~ 2–25 cm—nesting deeper within or outside of that range of depths to achieve higher soil moisture would also generally create cooler conditions for embryos that need adequate heat for successful development. In contrast, extreme deep nesting in V. panoptes allowed us to disentangle temperature and moisture. Broadly, our data suggest that ground-nesting reptiles can assess soil moisture and respond by adjusting the depth of the nest, but may not, due to the cooling effect of nesting deeper. Our results, within the context of previous work, provide a more complete picture of how mothers can promote hatching success through adjustments in nest site choice behavior.

Climate Change and Green Sea Turtle Sex Ratio—Preventing Possible Extinction

Climate change poses a threat to species with temperature-dependent sex determination (TSD). A recent study on green sea turtles (Chelonia mydas) at the northern Great Barrier Reef (GBR) showed a highly female-skewed sex ratio with almost all juvenile turtles being female. This shortage of males might eventually cause population extinction, unless rapid evolutionary rescue, migration, range shifts, or conservation efforts ensure a sufficient number of males. We built a stochastic individual-based model inspired by C. mydas but potentially transferrable to other species with TSD. Pivotal temperature, nest depth, and shading were evolvable traits. Additionally, we considered the effect of crossbreeding between northern and southern GBR, nest site philopatry, and conservation efforts. Among the evolvable traits, nest depth was the most likely to rescue the population, but even here the warmer climate change scenarios led to extinction. We expected turtles to choose colder beaches under rising temperatures, but surprisingly, nest site philopatry did not improve persistence. Conservation efforts promoted population survival and did not preclude trait evolution. Although extra information is needed to make reliable predictions for the fate of green sea turtles, our results illustrate how evolution can shape the fate of long lived, vulnerable species in the face of climate change.

The Role of Nest Depth and Site Choice in Mitigating the Effects of Climate Change on an Oviparous Reptile

Climate change is likely to have strong impacts on oviparous animals with minimal parental care, because nest temperature can impact egg development, sex, and survival, especially in the absence of mitigation via parental care. Nesting females may compensate for increasing temperatures by altering how, when, and where they nest. We examined the factors determining nest depth and site choice as well as the effects that nest depth and location have on nest temperature and hatching success in the diamondback terrapin (Malaclemys terrapin). We found that nest depth was not correlated with nesting female size, egg characteristics, or daily temperatures. Nest temperatures and hatching success were correlated with different environmental and nest characteristics between 2004, a cool and wet year, and 2005, a hot and dry year. Females selected nests with lower southern overstory vegetation in 2005. These results suggest that nest depth and location can play an important yet varying role in determining nest temperature and hatching success in more extreme warm and dry environmental conditions and, therefore, may mitigate the impacts of climate change on oviparous reptiles. However, we found minimal evidence that turtles choose nest locations and depths that maximize offspring survival based on short-term environmental cues.

Climate change and green sea turtle sex ratio – Preventing possible extinction

Climate change poses a threat to species with temperature-dependent sex determination. A recent study on green sea turtles (Chelonia mydas) at the northern Great Barrier Reef (GBR) showed a highly female-skewed sex ratio with almost all juvenile turtles being female. This shortage of males might eventually cause population extinction, unless rapid evolutionary rescue, migration or conservation efforts ensure a sufficient number of males. We built a stochastic individual-based model inspired by C. mydas, but potentially transferrable to other species with TSD. Nest depth, level of shade, and pivotal temperature were evolvable traits. Additionally, we considered the effect of crossbreeding between the northern and southern GBR, nest-site philopatry, and conservation efforts. Among the evolvable traits, nest depth was the most likely to rescue the population in the face of climate change, but even here the more extreme climate-change scenario led to extinction. Surprisingly, nest-site philopatry elevated extinction rates. Conservation efforts to artificially increase nest depth promoted population survival and did not preclude trait evolution. Although extra information is needed to make reliable predictions for the fate of green sea turtles, our results illustrate how evolution can shape the fate of long lived, vulnerable species in the face of climate change.Graphical Abstract

Thermal consequences of subterranean nesting behavior in a prairie-dwelling turtle, the Ornate Box Turtle (Terrapene ornata)

Many oviparous reptiles deposit eggs in excavated nest chambers, and the location and depth at which eggs are laid can affect predation risk, incubation duration, mortality rates, and hatchling phenotype. Among turtles, nest depth also influences incubation conditions of some large-bodied species, but nest depth is generally expected to vary less among small-bodied species. We monitored nesting behavior of Ornate Box Turtles (Terrapene ornata (Agassiz, 1857)) for two seasons in Illinois. We used direct observations to confirm that, among 31 nesting events, six females oviposited while beneath the substrate surface. Furthermore, comparisons of body length to nest depth indicated that five additional females likely also constructed nests while buried. Nests laid while females were underground were deeper, on average, than other nests (16.7 versus 11.2 cm), and while mean nest temperatures were similar between groups, temperature fluctuations and maximum temperatures were lower among nests that were laid while females were underground. Subterranean oviposition appears to have moderated incubation temperatures by allowing females to deposit eggs at greater depths than would be possible from the surface. This little-documented behavior may be a mechanism for this species to influence the incubation environment, which in turn may influence hatchling phenotypes.