130,421 research outputs found
Age and growth determination by skeletochronology in loggerhead sea turtles (Caretta caretta) from the Mediterranean Sea
Get PDFSkeletochronology was applied to humerus bones to assess the age and growth rates of loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea. Fifty-five dead turtles with curved carapace lengths (CCL) ranging from 24 to 86.5 cm were collected from the central Mediterranean. Sections of humeri were histologically processed to analyze annual growth marks. Two approaches were used to estimate the somatic growth in the form of a von Bertalanffy growth function. The first approach was based on calculating the total number of growth marks, which corresponds to the age of turtles at death. The second approach estimates the carapace length at old growth marks in order to provide the growth rate of each turtle. The observed individual growth rates ranged from 1.4 to 6.2 cm yr(-1), and showed both elevated inter- and intra-individual variability possibly related to the environmental variability experienced by turtles during their lifetime. Both approaches gave similar results and suggest that Mediterranean loggerhead turtles take 14.9 to 28.5 years to reach a CCL of 66.5 to 84.7 cm. This size corresponds to the average size of nesting females found in the most important Mediterranean nesting sites and can be considered the approximate size at maturity
Estimation of age at maturity of loggerhead sea turtles Caretta caretta in the Mediterranean using length-frequency data
No full textIt is widely accepted that the age at sexual maturity of sea turtles is a critical parameter for studying population dynamics and persistence. Estimates of the age at maturity for such longlived species are derived using somatic growth models, which are still lacking for several regions of the world. In the present study, the growth rate of the loggerhead sea turtle Caretta caretta in the Mediterranean was investigated using a length-frequency analysis of a dataset collected over a 19 yr period (1990 to 2008). A total of 2255 individuals were measured in the central Mediterranean, with turtle size ranging from 16.8 to 97.5 cm curved carapace length (CCL). Monthly length-frequency histograms were constructed, and strong size modes were identified, assumed to represent individual cohorts. Growth rates were calculated by tracking the progression of the modes, by means of a modal progression analysis. Annual growth rates ranged from 0.37 to 6.5 cm yr -1. A von Bertalanffy growth function was used to estimate the time required by turtles to grow within the observed size range. The results indicate that turtles would take from 23.5 to 29.3 yr to reach 80 cm CCL, considered an approximation of the size at maturity. This estimation integrates and confirms a previous estimate obtained using a different method. It provides information vital to understanding the population dynamics of loggerhead turtles in the Mediterranean, and highlights the value of datasets of longterm series when investigating critical demographic parameters. © Inter-Research 2011
Spatio-temporal distribution and migration of adult male loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea: further evidence of the importance of neritic habitats off North Africa
No full textTen adult male loggerhead sea turtles, captured by trawlers or dip nets, were satellite-tracked from a neritic foraging ground in the Mediterranean in order to investigate adult spatio-temporal distribution and breeding migration. Five individuals migrated to potential breeding sites in Libya and one to Greece. The results complement previous studies and show that: (1) the Tunisian shelf may be more important for turtles from Libyan rookeries than previously thought; (2) male tracks corroborate a conservation hotspot previously identified for juveniles; (3) the north African coast represents a preferred migratory corridor, unless open sea routes are more direct; (4) adult males may exhibit high fidelity to relatively small areas, without evident seasonal differences; (5) adults home ranges were smaller and more neritic than juveniles frequenting the same area; (6) males may frequent multiple courtship areas; (7) the average remigration interval of males frequenting this region is longer than 1 year. © 2012 Springer-Verlag Berlin Heidelberg
Mitochondrial DNA reveals regional and interregional importance of the central Mediterranean African shelf for loggerhead sea turtles (Caretta caretta).
Get PDFThe wide north African continental shelf in the central Mediterranean is known to be one of the few important areas in the basin for loggerhead turtles in the neritic stage. In order to assess the origin of these turtles, sequences of the mtDna control region were obtained from 70 turtles caught by bottom trawlers in the area, and compared with known sequences from turtles from Mediterranean and atlantic nesting sites. Five haplotypes were identified (Haplotype diversity = 0.262; nucleotide diversity = 5.4×10-3). Specific haplotypes indicate contributions from distant rookeries such as Turkey and the Atlantic, which shows that Atlantic turtles entering the Mediterranean while in the oceanic phase use at least one Mediterranean continental shelf as a neritic foraging ground. A new haplotype and another one previously found only in foraging areas, highlight the genetic information gaps for nesting sites, which undermine powerful mixed stock analyses. Despite these limitations, the results reveal the regional importance of the study area as a neritic foraging ground for turtles that are probably from most of the Mediterranean nesting aggregates. Therefore, reducing turtle mortality resulting from the high fishing effort in the area should be regarded as key for Mediterranean turtle conservation and is also possibly important for atlantic populations
Foraging ecology of loggerhead sea turtles Caretta caretta in the central Mediterranean Sea: evidence for a relaxed life history model
No full textIn the central Mediterranean Sea, gut contents and feces of 95 turtles captured by bottom trawlers and pelagic longliners fishing in neritic and oceanic areas, respectively, were examined. Benthic prey were more abundant than pelagic, a probable bias due to the higher digestibility of the latter. Animal and plant taxa belonging to 12 Phyla and 20 Classes were observed, with 63 new records of prey species, and Malacostraca, Gastropoda, and Echinoidea were the most commonly occurring animal classes. Results showed a highly opportunistic foraging behavior by the turtles on both live and dead material in the epipelagic zone as well as on all types of seafloor. Benthic taxa were found in turtles as small as 26 cm curved carapace length (CCL), indicating an early use of benthic resources, and also among turtles over a wide size range caught: by pelagic longliners. The lack of evidence of a strict oceanic/pelagic stage and of a clear habitat shift in the observed size range (25 to 80.3 cm CCL), when considered together with other recent findings, challenges the current ontogenetic model of life history for the species. A relaxed model is proposed, with an early short obligate epipelagic stage due to limited diving capacity, followed by the main opportunistic amphi-habitat stage, with a tendency to prefer benthic prey as turtles grow and their benthic foraging efficiency improves. Under this model, temporary or permanent association or fidelity to specific oceanic or neritic zones would vary among individuals or populations according to food availability and oceanographic features in the foraging or migratory areas
First evidence of migration by loggerhead sea turtles, Caretta Caretta, from the eastern Mediterranean to North America
No full textLoggerhead sea turtles (Caretta caretta) frequent very distant areas during their life stages, and information about migratory routes and geographical range is key for planning their conservation. Here we report on the first direct evidence of a loggerhead turtle migrating from the eastern Mediterranean to the North American coast. A juvenile of 57.1 cm curved carapace length was tagged and released from Lampedusa Island, Italy, in 2008 and found dead on the Massachusetts coast in 2012. Its size and first location fit with the current knowledge about Atlantic loggerheads entering the Mediterranean and this finding supports the hypothesis of homing behavior as the explanation for the low genetic flow estimated between the Atlantic and Mediterranean populations
Comparision between left and right surgical approach through the soft tissues of the inguinal region in sea turtles.
No full textThe accidental capture of sea turtles with longline is a frequent event
in the Mediterranean sea. Frequently hooks are located in oral cavity
or oesophagus and surgical removal is relatively easy; whereas in
many other cases hooks and especially lines are located in lower
digestive tract, often causing severe damages, as serious injuries
on the intestinal wall. Recently, effective surgical techniques have
been proposed for hook and line extraction from different districts
of digestive tract. The access to the coelomic cavity through the
prefemoral soft tissues allows the removal of hooks and lines from
the caudal portions of the digestive tract and it is often employed
in conjunction with cervical or axillary approach, if one or more
hooks are located in oesophagus or stomach and lines cross the
entire digestive tract. In this study, the left inguinal approach is
compared to the right one, and results are reported concerning 97
turtles treated by these routes for the extraction of foreign bodies
from digestive tract. The surgical approach through soft tissues of
the right inguinal region was performed in 63 turtles. In 23 cases
a unique approach was used to remove hooks lodged in the lower
digestive tract and lines extended through the entire digestive tract.
In 40 cases this approach was performed together with cervical
and left axillary surgical approaches, to remove hooks lodged in
oesophagus or stomach, and lines crossing the lower digestive tract.
The surgical approach through the soft tissues of the left inguinal
region was performed in 34 turtles. This technique was employed
as a single approach in 5 cases to remove hooks stopped in the
pyloric portion of the stomach, and in 10 cases to remove lines
crossing the entire digestive tract. In the remaining 19 cases the
left inguinal approach was employed additionally to the cervical
one, to remove hooks lodged in the oesophagus and lines extended
through the entire digestive tract. To remove hooks located in the
intestine, we chose the side closest to the site of the foreign body.
To remove line crossing all the digestive tract, the choice of the
side access was initially random, but experience showed how the
right inguinal approach is to be preferred. Indeed, we tested how
this approach allows the exteriorization of longer tracts of intestine,
whereas with the left inguinal approach is often difficult to expose
the tract between jejunum and ileum, because this portion is more
subject than others to plication, intussusceptions and severe
lacerations of walls, because of the major tensions that line induces
there. To guarantee the survival of the patient, our direct experience
show definitely how it is important to operate as soon as possible,
in particular when it could be present a line in the digestive tract.
The choice of the surgical approach appears crucial to solve lifethreatening situations, in which lines cross the entire digestive tube
An unusual nest activity along southern Sicilian coasts an hope for sea turtle survival.
No full textPreliminary work on vitellogenin purification from serum of Caretta caretta collected at the WWF Seaturtle Rescue Center of Lampedusa, Sicily (Italy).
No full textThe presence of vitellogenin in male is a useful marker of endocrine disruption in oviparous vertebrates such as seaturtles and its quantification helps to evaluate the habitats’ quality.
Considering the lack of commercial systems for vitellogenin analysis and the lack of specific standards for seaturtles we focused the work on the definition of a reliable method for vitellogenin purification and quantification in Caretta caretta.
Heparinized blood (2 cc) samples were collected, after morphological measurement, from individuals of Caretta caretta hospitalized at the WWF Seaturtle Rescue Center Lampedusa, Sicily (Italy) and obtained plasma was stored frozen at –20°C till analysis.
For VTG purification 100 ml of each serum’s samples was used. The VTG purification was obtained by precipitation while its quantification was performed by spectrophotometric method, using standard staining and protocol (“DC protein assay”, BIORAD).
VTG levels are in agreement with subjects gender. The marker was detected in all animals, even if in male turtles the levels were very low.
Overall, there seems to be no risk for reproductive health of seaturtles from Sicily
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