Straight-line Carapace Length Research Articles

Investigation on anthropogenic and opportunistic factors relevant to the incidence of stranded loggerhead sea turtle Caretta caretta along South Tyrrhenian coasts

Caretta Caretta are endangered sea turtles leaving in the Mediterranean Sea. We carried out a study on 195 sea turtles stranded along the coast of Southern Italy, evaluating anthropogenic and opportunistic factors affecting animal health status and probably threatening the species. More than 60% of the animals showed body injuries, mainly caused by marine traffic and fishing. Ingestion of marine litter of various origins was observed in the digestive tract of 38.5% of the turtles investigated. Chelonid herpesvirus 5 was detected (for the first time in this basin) in 10.8% of the turtles, which were however free from fibropapillomatosis. Analyses on trace elements showed a time-dependent reduction in the mean concentrations of Cd and Hg, a decrease in the levels of Pb, and a time-dependent increase of As. Particularly, a site-dependent accumulation of As was detected in turtles from the coasts of Calabria. There is a significant correlation between the levels of As in the kidney of Campania turtles and their straight-line carapace length, indicating a size-dependent accumulation of this metal. Overall, besides dangerous debris items, high levels of trace elements may weaken the immune system of Caretta caretta, the most common turtle of the Mediterranean Sea, making it more likely vulnerable to viruses.

A New South American Freshwater Turtle of the Genus Mesoclemmys from the Brazilian Amazon (Testudines: Pleurodira: Chelidae)

We describe a new species of small chelid turtle from perennial streams in the Araguaia River subbasin near Serra das Andorinhas State Park, São Geraldo do Araguaia, Pará, Brazil. It is morphologically distinct and the smallest known member of the genus Mesoclemmys, with an average straight-line carapace length (CL) of 144 mm and maximum recorded CL of 170 mm. The species has a moderate head width of approximately 20% of CL. The carapace and dorsal soft parts are blackish, the plastron is light brownish yellow with a blackish brown central plastral figure, and the ventral soft parts are pale yellow. It has the largest femoral scutes of any Mesoclemmys and its plastral contact formula is Intergular > Anal > Humeral > Femoral > Abdominal > Pectoral > Gular. We describe the shell and skull morphology of the new species and performed genetic analysis using mitochondrial DNA (cytochrome c oxidase, subunits I [COI] and 16S) to build a phylogenetic tree for the genus, which placed the new species as sister to M. vanderhaegei.

Reproductive biology of the Rote Snake-necked Turtle Chelodina mccordi (Rhodin, 1994) in Oelsonbai Captivity, Kupang

The Rote snake-necked turtle (Chelodina mccordi Rhodin, 1994) or Kura-kura Leher Ular Rote is an endangered species endemic to Rote Island, East Nusa Tenggara. It is listed as Critically Endangered by the IUCN. However, based on surveys in recent years, C. mccordi was presumed extinct in the wild. Ex-situ conservation is one alternative to conserve C. mccordi. The purpose of this paper is to describe the reproductive biology of the Rote snake-necked turtle in captivity. Three (one male and two female) C. mccordi were observed in Oelsonbai captivity, Kupang, from 2009 to 2020 to obtain data on the species’ reproductive biology. The first mating behaviour was observed when the turtles were six years old. Hatches occurred two or three times a year, with clutch size varied from five to twenty eggs. Egg hatchability was 75-100 percent, with an incubation period of 76 to 102 days. Female size when mature straight-line carapace length (SCL) 178 mm, carapace width 145 mm, and plastron length 142 mm. Male size straight-line carapace length (SCL) 190 mm, carapace width 150 mm, and plastron length 143 mm.

Home Ranges and Movement Patterns of the Chinese Softshell Turtle (Pelodiscus sinensis) in the Yellow River, Northwestern China

A detailed understanding of the spatial ecology and habitat requirements of endangered species is critical for population restoration and conservation. Home ranges and movements of the endangered Chinese softshell turtle (Pelodiscus sinensis) were investigated in the Yellow River, northwestern China, from October 2016 to July 2018. We monitored 9 adult turtles (5 females and 4 males) with radio transmitters. Mean linear range size was 440 ± 161 m SD, mean river channel area was 1.98 ± 0.72 ha SD, the average minimum convex polygon was 1.36 ± 0.65 ha SD, average 95% kernel density estimator measured 0.84 ± 0.51 ha SD, with a core area (50% kernel density estimator) of 0.30 ± 0.20 ha SD. Home range values were not significantly different between the sexes nor were they related to straight-line carapace length or mass. Daily movements of P. sinensis averaged 35 ± 18 m SD for males and 43 ± 18 m SD for females, and there was no significant difference between sexes or significant correlation between movement patterns and body size. However, during the nesting season, there was a significant difference between sexes. Turtle activity was highest in May (average daily movement 59 ± 6 m SD) and lowest in January (0.4 ± 0.6 m SD). Given that P. sinensis individuals have small home ranges and are capable of existing in small rivers, management efforts should protect smaller rivers that may be easily overlooked. Results from this study provide the first assessment of home range requirements for P. sinensis, which may be used in future population modeling efforts and are important for establishing conservation strategies for this vulnerable species.

Hawksbill sea turtle life-stage durations, somatic growth patterns, and age at maturation

Sea turtles exhibit complex life histories, encompassing intermittent use of multiple spatially separated habitats throughout long lifespans. This broad scope presents challenges for collecting comprehensive biological and ecological data, yet absence of such information complicates evaluation of management strategies for populations at risk of extinction. Hawksbill sea turtles Eretmochelys imbricata are endangered worldwide, primarily due to long-term, directed harvest. However, available information regarding life stage durations, somatic growth patterns, and maturation attributes to enhance understanding of anthropogenic impacts and recovery potential remains constrained. To address these data gaps in the western North Atlantic, we conducted skeletochronological analysis for hawksbills stranded along US coastlines to generate straight-line carapace length (SCL)-at-age and somatic growth data. Generalized additive mixed models and bootstrapped von Bertalanffy growth curves were used to characterize age at maturation and covariate influence on somatic growth. For a subset of turtles, annual bone growth increment-specific stable isotope and trace element analyses were incorporated to evaluate habitat use relative to age. Integration of these data sources indicated that juveniles transitioned from oceanic to neritic habitat at 1-3 yr old and mean SCLs of 23-24 cm (range 15.7-35.0 cm). Initial ages at maturation for this population at minimum nesting female SCLs were estimated at 15-25 yr. Somatic growth varied significantly relative to size, age, and stranding location, while no association with sex or calendar year was observed. Our results demonstrate the utility of these complementary analytical approaches for generating baseline data fundamental to characterizing hawksbill sea turtle population attributes.

Tasas de crecimiento somático de tortuga carey, Eretmochelys imbricata, en el Parque Nacional Natural Gorgona, Colombia, entre 2004 y 2018

La tortuga carey, Eretmochelys imbricata, se encuentra a nivel global en peligro crítico de extinción, y la información demográfica en el Océano Pacífico Oriental es limitada. Por esta razón, esta investigación evalúa las tasas de crecimiento somático en una agregación de individuos inmaduros de tortuga carey empleando el método de captura-marca-recaptura en los arrecifes coralinos de Playa Blanca y la Azufrada en el Parque Nacional Natural Gorgona, Colombia. Entre 2004 y 2018 se realizaron 89 capturas de 49 individuos de tortuga carey. El largo curvo del caparazón promedio (LCC) obtenido fue de 41,6 cm (rango 32-58 cm) y el largo recto del caparazón promedio (LRC) fue de 39,1 cm (rango 30,0-54,1 cm), lo que muestra que estos arrecifes son áreas de forrajeo importantes para individuos inmaduros de esta especie. El índice de condición corporal promedio fue de 1,3 (rango 1,0-1,5). Esto sugiere que las condiciones ambientales mantienen en buen estado la salud de esta agregación. Usando el modelo de crecimiento de von Bertalanffy y estableciendo una talla máxima (L∞) de 63 cm de LCC (donde se obtiene el menor coeficiente de variación), se estimó una k de 0,081 y una tasa anual de crecimiento promedio de 1,5 ± 1,8 cm/año. Esto indica que los individuos en esta agregación estarían alcanzando una LCC de 63 cm entre los 33 y 34 años, talla cercana a la de madurez sexual en la región del Pacífico oriental (aproximadamente 66 cm LCC). Lo anterior ratifica la vulnerabilidad de esta especie debido a las lentas tasas de crecimiento somático y madurez sexual tardía. Se sugiere que los esfuerzos de conservación para esta especie deben ser a largo plazo para procurar su recuperación, en vista de que especies con estas características tienden a expresar tasas de crecimiento poblacional muy bajas.

ASSESSMENT OF POPULATION CHARACTERISTICS AND HABITAT USE OF Podocnemis vogli (MÜLLER 1935) DURING A REPRODUCTIVE SEASON AT THE BOJONAWI PRIVATE NATURE RESERVE (VICHADA DEPARTMENT, COLOMBIA)

We conducted a short study in the Bojonawi Private Nature Reserve (Vichada department, Colombia) in three types of aquatic macrohabitats to characterize habitat use, population structure and reproductive phenology of Podocnemis vogli during one reproductive season. We also reevaluated the degree of sexual dimorphism in this species. To maximize capture rates, we used three methods: funnel traps, trammel nets, and manual capture. Only the funnel traps could be used in a standardized manner in all three macrohabitats. We captured 149 individuals in all age/size classes and obtained 11 recaptures. Since we were able to standardize sampling effort with the funnel traps in all macrohabitats, we compared habitat use and class structure among habitats during this reproductive season. There were no significant differences among the three macrohabitats in terms of relative abundances or size class distributions, but sex ratios differed, with an excess of males in the river and females in the lagoon. As with other congeners, P. vogli is a sexually dimorphic species where females attain larger sizes. In this study we documented that pre-cloacal tail length and nail length on the anterior third toe are the most useful secondary sexual characteristics for sexing subadult and adult individuals. Some females larger than 22 cm straight-line carapace length had calcified eggs in their oviducts. This species is abundant within the reserve and appears to be a habitat generalist, including the use of large rivers. More extensive and intensive monitoring is needed to document specific class survivorship rates, detectabilities and population dynamics.

First description of neonate Batagur trivittata (Testudines: Geoemydidae).

The Burmese Roofed Turtle (Batagur trivittata Duméril Bibron, 1835) is a large (straight-line carapace length [CL] to 620 mm; Platt et al., 2019), aquatic, herbivorous turtle endemic to the major river systems of Myanmar (Smith 1931; TTWG 2017). Although historically widespread and apparently abundant, long-term population declines resulted from chronic egg collecting, subsistence harvesting of adults, and loss of critical nesting habitat (Platt et al. 2017a). By the late 1990s B. trivittata was considered a candidate for Extinct status (Bhupathy et al. 2000) until a living specimen purchased in a Chinese wildlife market came into the possession of an American turtle collector in the early 2000s (Platt et al. 2005; W.P. McCord, pers. comm.). Shortly thereafter, field surveys "rediscovered" two remnant populations in the Dokhtawady and upper Chindwin Rivers (Platt et al. 2005; Kuchling et al. 2006). Intense ex- and in-situ recovery efforts were launched shortly thereafter and continue today (Kuchling Tint Lwin 2004; Çilingir et al. 2017).

Biphasic allometric growth in juvenile green turtles Chelonia mydas

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 37:301-308 (2018) - DOI: https://doi.org/10.3354/esr00930 Biphasic allometric growth in juvenile green turtles Chelonia mydas Michael Salmon1,*, Cody R. Mott2, Michael J. Bresette2 1Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, 33431, USA 2Inwater Research Group, Jensen Beach, Florida 34957, USA *Corresponding author: salmon@fau.edu ABSTRACT: Green turtles raised in the laboratory widen faster than they lengthen, thus changing in shape from the proportions they show as hatchlings. By doing so, young turtles may sooner achieve a size refuge from their gape-limited predators. In this study, we document that wild juveniles captured at open-water weed lines in the Gulf of Mexico show similarly wider proportions, demonstrating for the first time that this growth pattern occurs in nature. We additionally quantified the shell dimensions of older juveniles that had abandoned weed lines and returned to occupy shallow coastal reefs. Those turtles exhibited a narrower ’hatchling like’ body shape. We conclude that juvenile green turtles show a biphasic pattern of initial widening, followed later by a secondary narrowing once they achieve a size that exceeds 25-30 cm in straight-line carapace length. We hypothesize that secondary narrowing may be advantageous for reducing lethal interactions with a different subset of larger predators, those that typically dismember their prey rather than swallow them whole. Finally, we categorize this complex growth pattern as one of several vulnerability traits that promote juvenile turtle survival, and document that they are expressed in different combinations among other marine turtle species. KEY WORDS: Allometric growth · Evolution · Predator-prey · Sea turtle · Vulnerability traits Full text in pdf format PreviousCite this article as: Salmon M, Mott CR, Bresette MJ (2018) Biphasic allometric growth in juvenile green turtles Chelonia mydas. Endang Species Res 37:301-308. https://doi.org/10.3354/esr00930 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 37. Online publication date: December 13, 2018 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2018 Inter-Research.

Breeding Success of Captive Black Turtles in an Aquarium

We bred black turtles (Chelonia agassizii) in captivity to improve our understanding of the reproductive biology of this species. One male and one female black turtle were maintained in a single outdoor tank with an openwater system at the Ocean Expo Park, Okinawa, Japan. Ultrasonographic observations indicated that the female (straight-line carapace length: 810 mm, body mass: 91.6 kg) first exhibited follicular development during March 2017. In May 2017, the male mounted the female for approximately 120 min, during which copulation occurred. The female later laid five clutches; the first eggs were released under water 32 days after mating, because of the absence of a suitable nesting substrate. After the female was transferred to another tank with an artificial beach, the second, third, and fifth clutches were laid on an artificial beach between July and August, but the fourth clutch was released underwater again. The mean (±standard deviation) internesting interval, clutch size, and egg diameter were 11.8±3.1 (range: 9–16) days, 45.2±13.8 (29–67) eggs, and 45.3±0.7 (44.0–47.0) mm, respectively. Hatchlings emerged from clutches 52–57 days after egg laying, with a total emergence success rate of 12.1% (14 hatchlings from 116 eggs). The straight-line carapace length and body mass of hatchlings were 48.8±2.0 (44.0–51.2) mm and 27.6±2.1 (24–30) g, respectively. This study is the first to report the breeding success of black turtles in captivity.

Variability in age and size at maturation, reproductive longevity, and long-term growth dynamics for Kemp's ridley sea turtles in the Gulf of Mexico.

Effective management of protected sea turtle populations requires knowledge not only of mean values for demographic and life-history parameters, but also temporal and spatial trends, variability, and underlying causes. For endangered Kemp’s ridley sea turtles (Lepidochelys kempii), the need for baseline information of this type has been emphasized during attempts to understand causes underlying the recent truncation in the recovery trajectory for nesting females. To provide insight into variability in age and size at sexual maturation (ASM and SSM) and long-term growth patterns likely to influence population trends, we conducted skeletochronological analysis of humerus bones from 333 Kemp’s ridleys stranded throughout the Gulf of Mexico (GOM) from 1993 to 2010. Ranges of possible ASMs (6.8 to 21.8 yr) and SSMs (53.3 to 68.3 cm straightline carapace length (SCL)) estimated using the “rapprochement” skeletal growth mark associated with maturation were broad, supporting incorporation of a maturation schedule in Kemp’s ridley population models. Mean ASMs estimated from rapprochement and by fitting logistic, generalized additive mixed, and von Bertalanffy growth models to age and growth data ranged from 11 to 13 yr; confidence intervals for the logistic model predicted maturation of 95% of the population between 11.9 and 14.8 yr. Early juvenile somatic growth rates in the GOM were greater than those previously reported for the Atlantic, indicating potential for differences in maturation trajectories between regions. Finally, long-term, significant decreases in somatic growth response were found for both juveniles and adults, which could influence recruitment to the reproductive population and observed nesting population trends.

Effect of diet on growth in captive Podocnemis unifilis: assessing optimal diets for turtles in head-starting programs

Because turtles have come under increasing pressures from habitat loss and over-exploitation as food sources and traditional medicine, efforts have focused on options for conservation, including head-starting programs. Success of head-starting programs depends on establishing economical means of rearing hatchlings over relatively short time frames to sizes resistant to predation. We examined effects of three different diets on growth of a clutch of captive Yellow-spotted Amazon River Turtles (Podocnemis unifilis) over a two-year period in a Florida zoo. Rates of growth differed among the three treatment groups; relationships between morphological variables were not affected by diet. Results indicate that turtles fed on a commercial gel diet may exceed growth rates of animals fed on a more natural, vegetarian diet by more than 15% as measured by straight-line carapace length, or by more than 50% in body mass. Use of a vegetarian diet reduced costs to less than 10% of the cost of a commercial gel diet. Choice of diets for turtles in head-starting programs is a variable that should be weighed against other conservation objectives such as captive duration and intended sizes attained.

Life History and Demographic Characteristics of the Magdalena River Turtle (Podocnemis lewyana): Implications for Management

We conducted a four-year study of the life history parameters of the endangered freshwater turtle Podocnemis lewyana (Testudines: Podocnemididae) in four channels connecting wetlands to the Magdalena River in northern Colombia. Using capture–mark–recapture techniques, we documented body size growth rates, sex ratios, and size class distributions, and estimated survival rates for juveniles and adults. We also used body size/clutch size and body size/track width correlations to estimate the body sizes of females that nested in beaches in the Magdalena River near the study sites. The body size at first nesting (30 cm straight-line carapace length) was comparable to the estimate obtained by inspecting the reproductive tracts of 70 females using a sonograph. Growth rate analyses showed adult males to be smaller than adult females with an estimated size at sexual maturity of 20 cm straight-line carapace length. Females begin nesting at 5–6 years of age and may lay up to four clutches annually with a mean clutch...

Patterns of loggerhead turtle ontogenetic shifts revealed through isotopic analysis of annual skeletal growth increments

Ontogenetic changes in resource use often delimit transitions between life stages. Ecological and individual factors can cause variation in the timing and consistency of these transitions, ultimately affecting community and population dynamics through changes in growth and survival. Therefore, it is important to document and understand behavioral and life history polymorphisms, and the processes that drive intraspecific variation in them. To evaluate juvenile loggerhead sea turtle (Caretta caretta) life history variation and to detect shifts in habitat and diet that occur during an oceanic‐to‐neritic ontogenetic shift, we sequentially analyzed the stable isotope composition of humerus bone growth increments from turtles that stranded dead on Southeastern U.S. beaches between 1997 and 2013 (n = 84). In one‐half of the sampled turtles, growth increment‐specific nitrogen stable isotope (δ15N) data showed significant increases in δ15N values over each turtle's life. These data were used to provide a new line of evidence that juvenile Northwest Atlantic loggerheads exhibit two major ontogenetic shift patterns: discrete shifts (n = 24), which were completed within one year, and facultative shifts (n = 14), which were completed over multiple years (up to five). The mean difference in pre‐ and post‐ontogenetic shift δ15N values was 4.3‰. Differences in isotopic baselines between neritic and oceanic habitats of the Northwest Atlantic Ocean make it likely these patterns are driven by a coupled change in both habitat and diet, and that facultative shifters utilize both neritic and oceanic resources within transitional growth years. Mean size and age at transition between habitats (54.2 cm straightline carapace length, SCL; 11.98 yr) was within the range of previous estimates and did not differ between discrete and facultative shifters. Our results further expand our understanding of loggerhead sea turtle life history polymorphisms and demonstrate the value of bone tissue analysis to the study of this variation. Sequential analysis of annual skeletal growth increments provides a valuable method for reconstructing long‐term ontogenetic changes in foraging ecology and habitat use in long‐lived, cryptic marine species.

Age and size at maturation- and adult-stage duration for loggerhead sea turtles in the western North Atlantic

Age at maturation data are integral to understanding dynamics of threatened and endangered sea turtle populations. However, full characterization of this parameter requires information regarding variability in growth rates and both size and age at maturation potentially resulting from diverse environmental and biological influences. To address the need for these data, skeletochronological analysis was conducted for US Atlantic loggerhead sea turtles Caretta caretta. The influence of different covariates on back-calculated growth rates for the years 1976–2010 was investigated, and while growth decreased overall with size and age, at larger sizes, male growth rates were higher than those of females. Growth varied significantly by calendar year, increasing from 1990 to 1996/1997 and subsequently decreasing through the end of the study period. Mean sizes [cm straightline carapace length (SCL)] corresponding to the “rapprochement” skeletal growth mark associated with maturation were 90.5 for females (range 75.0–101.3) and 95.8 for males (range 80.6–103.8). Ages at maturation estimated from (1) the rapprochement skeletal growth mark; (2) back-calculated SCL-at-age data; and (3) bootstrapping and fitting Fabens modified von Bertalanffy growth curve to back-calculated growth data were very similar between approaches, but demonstrated a wide possible range. Mean age predictions associated with minimum and mean maturation SCLs were 22.5–25 and 36–38 years for females and 26–28 and 37–42 years for males. Post-maturation longevity (i.e., adult-stage duration) was similar for males and females, ranging from 4 to 46 years (mean 19 years).

Spatial and temporal patterns of harvesting of the Vulnerable pig-nosed turtle Carettochelys insculpta in the Kikori region, Papua New Guinea

AbstractManagement of wildlife use by communities living a partially traditional lifestyle is usually more successful when the interactions between those communities and the environment are well understood. We mapped the harvest areas for the Vulnerable pig-nosed turtle Carettochelys insculpta for six language-groups in the Kikori region of Papua New Guinea and compared harvest parameters between different areas and language-groups and, when possible, between 1980–1982 and 2007–2009. Spatially, the main influence on harvest method was a tribe's location relative to the turtle's distribution. No small juveniles (< 20 cm straight-line carapace length) were found outside the Kikori delta, which is probably the species’ feeding grounds. In contrast, nesting females were captured only in upstream and coastal sandbank areas. Temporally there were distinct differences in harvesting parameters between tribes, which may be explained by differential employment opportunities. To halt the decline of pig-nosed turtles in the Kikori region we recommend the establishment of beach and feeding-ground protection initiatives, together with monitoring of the turtle population and harvest. Concomitantly, trips specifically targeted at harvesting the turtles, which account for 81% of the animals captured, need to be restricted. These initiatives should include all six language-groups and take into account their specific harvesting patterns.

Abundance and Population Structure ofPodocnemis erythrocephala(Testudines, Podocnemididae) in the Unini River, Amazonas

Abstract We studied the population structure, sex ratio, and abundance of a locally endangered species of freshwater turtle, the red-headed river turtle (Podocnemis erythrocephala), in the Unini River in Negro River Basin in Brazil with capture–recapture of marked individuals in 1 yr, including both dry and rainy seasons. We used trammel nets of 3 different inner mesh sizes in the lakes. The nets were revisited at 3-hr intervals from 0600 to 1800 hrs each day. All turtles were released after being marked, measured, and sexed. During the study, 352 individuals were marked including 162 males, 150 females, and 40 immatures. The majority of the turtles (79%) were captured in the dry season when the water level of the river was declining. Mean ± standard deviation straight-line carapace length was 210 ± 14 mm (range 163–262 mm) for males and 251 ± 18 mm (221–303) for females. Most turtles captured were in the intermediate size classes: 200–210 mm for males and 230–270 mm for females. The sex ratio of adults i...

Morphological Variation inChelonia mydas(Linnaeus, 1758) from the Coastal Waters of Japan, with Special Reference to the Turtles Allied toChelonia mydas agassiziiBocourt, 1868

Abstract: Morphological variations were analyzed for green turtles, Chelonia mydas, on the basis of 127 individuals captured in the coastal waters of Japan. They were explicitly divided into two groups by plastral coloration—the yellow type and the black type. To statistically assess the morphometric differences between these color types, analysis of covariance was performed for each of 28 external measurements using the standard straight-line carapace length (SCL) as the covariate. Results indicated that the yellow and black types significantly differ in ratios to SCL of distances from the nuchal notch to the outermost point of boundry between the 11th and the preceding (10th) marginals, and also to the boundary of the 11th marginal, last (fifth) vertebral, and last (fourth) pleural on both sides. Such morphometric covariations with plastral coloration in C. mydas sensu lato, as well as sympatric occurrences of the two color types in the Japanese waters, collectively support the validity of the black typ...

Complementary skeletochronology and stable isotope analyses offer new insight into juvenile loggerhead sea turtle oceanic stage duration and growth dynamics

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 491:235-251 (2013) - DOI: https://doi.org/10.3354/meps10454 Complementary skeletochronology and stable isotope analyses offer new insight into juvenile loggerhead sea turtle oceanic stage duration and growth dynamics Larisa Avens1,*, Lisa R. Goshe1, Mariela Pajuelo2, Karen A. Bjorndal2, Bradley D. MacDonald3, Garrett E. Lemons4, Alan B. Bolten2, Jeffrey A. Seminoff3 1NOAA Fisheries, Southeast Fisheries Science Center, Beaufort Laboratory, 101 Pivers Island Road, Beaufort, North Carolina 28516, USA 2Archie Carr Center for Sea Turtle Research and Department of Biology, University of Florida, PO Box 118525, Gainesville, Florida 32611, USA 3NOAA National Marine Fisheries Service, Southwest Fisheries Science Center, 86014 La Jolla Shores Drive, La Jolla, California 92037, USA 4Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, California 92115, USA *Email: larisa.avens@noaa.gov ABSTRACT: Stage durations are integral to wildlife population models that can inform management, as they influence age at maturation and stage-specific survival rates. To refine oceanic stage duration estimates for western North Atlantic loggerhead sea turtles Caretta caretta, skeletochronological analysis was conducted on humeri collected in the Azores islands and along the US Atlantic coast. Complementary skeletal growth increment-specific stable isotope analysis was also performed for a sub-set of the humeri, to identify the skeletal growth mark associated with the shift from oceanic to neritic habitat through stable nitrogen isotope (δ15N) values and the presence of turtles in inshore waters. Although the transitional growth mark in this sub-sample corresponded to a range of sizes similar to those described in previous studies, mean size at recruitment (55.3 cm straightline carapace length [SCL]) for these turtles was larger than previously estimated. Similarly, while the range of ages at recruitment—corresponding both with the transitional growth mark and those yielded by fitting smoothing splines to SCL-at-age data—overlapped almost fully with earlier estimates, the mean age estimate (12.4 yr) differed from previous studies. Validated back-calculation of somatic growth rates from skeletal growth marks yielded means and ranges that encompassed those of previous loggerhead growth studies in this geographic area. Generalized additive models and generalized additive mixed models used to assess the potential influence of discrete and continuous covariates on back-calculated growth rates spanning 1984 to 2009 indicated significant effects of age, SCL, calendar year, and δ15N, but none for sex or location. KEY WORDS: Caretta caretta · Age · Skeletal growth marks · Life history · Ontogenetic habitat shift Full text in pdf format Supplementary material PreviousNextCite this article as: Avens L, Goshe LR, Pajuelo M, Bjorndal KA and others (2013) Complementary skeletochronology and stable isotope analyses offer new insight into juvenile loggerhead sea turtle oceanic stage duration and growth dynamics. Mar Ecol Prog Ser 491:235-251. https://doi.org/10.3354/meps10454 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 491. Online publication date: October 02, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Alometria reprodutiva de Podocnemis unifilis (Testudines: Podocnemididae) na várzea do baixo rio Amazonas, Santarém, Pará, Brasil

O tamanho do corpo dos organismos representa um parâmetro importante, podendo gerar consequências na sua ecologia, atividades reprodutivas, evolução e desenvolvimento. Relação alométrica é o estudo do tamanho (ou do crescimento) de uma parte do corpo relacionado com o tamanho (ou crescimento) total do corpo do organismo. Este estudo analisou a relação alométrica entre as fêmeas de Podocnemis unifilis (Troschel, 1848) e seus ovos e filhotes e entre as características dos ninhos e a ninhada em uma área de várzea do baixo rio Amazonas, estado do Pará, Brasil. As ninhadas de P. unifilis foram monitoradas no Tabuleiro da Água Preta durante o período reprodutivo de 2009. As fêmeas encontradas desovando foram medidas e seus respectivos ninhos marcados com estacas numeradas e as características físicas mensuradas. Os ovos e filhotes destes ninhos foram retirados e contados, e tiveram seus dados biométricos tomados. Os parâmetros das fêmeas analisados (comprimento retilíneo da carapaça e massa) correlacionaram-se fortemente às variáveis dos ovos (variável x) e filhotes (variável y), exceto com o comprimento do ovo e com a massa do filhote. Estudos futuros direcionados para melhor compreensão de como as características ambientais influenciam nas ninhadas podem ser aplicados, sendo úteis no manejo da espécie.