Estudio de los sonidos emitidos por las crías de tortuga boba, Caretta caretta, en el momento de la eclosión

Las crías Caretta caretta durante la eclosión y antes de salir del nido, emiten sonidos asociados a crujido y raspado del corion, así como chillidos, silbidos y tos, en un rango de frecuencia entre los 300 y 2600 Hz. No obstante, los silbidos y chillidos, que pueden ser asociables a un sistema de vocalización, se emiten a una frecuencia (1500-2600 Hz) mucho mayor al rango de sensibilidad descrito para esta especie (250-1000 Hz) y por tanto imperceptibles para ellas. Sin embargo, los sonidos producidos como consecuencia de ejercicios de respiración y expulsión de arena de las vías respiratorias, acompañados de tos (300-1200 Hz), por parte de las crías recién eclosionadas, son los únicos sonidos que podrían servir de señal y estimulación a la eclosión del resto de crías en el nido. ABSTRACT The hatchlings Caretta caretta, during the eclosion and before the abandon of their nest, produce sounds associated to creakling and scrape of the eggshell, and howl, whistle and cough, in a frequency range between 300 and 2600 Hz. Nevertheless, the howls and whistles, that could be associated to a vocalization apparatus, were emitted at a higher frequency (1500-2600 Hz) than the auditory range describe for this species (250-1000 Hz), and therefore probably inaudible for them. However, sounds generated as a consequence of breathing exercises and sand expulsion from the airways through coughs (300- 1200 Hz), by the recently hatched turtles, could be used as signal or stimulus for the hatch of the reminder eggs in the nest.

Estudio de la selección por el color del alimento en la tortuga boba Caretta caretta tras la eclosión

The behavior of newborn pups of loggerhead turtles (Caretta caretta) towards a potential food after hatching and before eating food for the first time was studied. There was no significant time trend approach and bite of potentially edible objects based on their color or size. However, a clear trend was observed for those objects that are transparent, white or red, independently the sex of the animal. Furthermore, it was verified that the turtles do not have a biting behavior to feed from first contact with water, but it comes after 3 or 4 days. There is also a learning process that determines the choice of targets of further attacks.

Ecosistemas errantes: Epibiontes como indicadores biogeográficos de tortugas marinas de Canarias

Programa de doctorado: Ecología y gestión de recursos vivos marinos

Paleontological studies of Cretaceous vertebrate fossil beds in the Tataouine Basin (southern Tunisia)

The ‘Continental Intercalaire’ deposits of the Tataouine basin of southern Tunisia preserve one of the most diverse Cretaceous vertebrate fauna from Africa. This research project focuses on a detailed revision of the stratigraphic distribution of mid-Cretaceous fossil beds in the Tataouine Basin and includes the description of four, newly discovered vertebrate tracksites. In the Tataouine region, macro- and microvertebrate remains are recovered from three stratigraphic intervals: the lower Douiret Formation (Barremian), the Chenini (rare) and Oum ed Diab members of the Aïn El Guettar Formation (Albian). A detailed, basin-scale revision of the stratigraphic occurrence of fossil-bearing strata indicates 1. lateral facies variability within the context of a low gradient, circalittoral to coastal-plain environment; 2. multiple and diachronous fossil beds which include elasmobranchs, actinopterygians, sarcopterygians, turtles, crocodyliforms, pterosaurs, and non-avian dinosaurs remains. Four vertebrate tracksites have been discovered in the study area: 1. the Middle Jurassic Beni Ghedir site which preserves approximately 130 tridactyl footprints distributed over an area of 200 square meters, representing the oldest evidence of a dinosaur fauna in Tunisia; 2. the late Albian Chenini tracksite, which includes poorly preserved crocodilian tracks and the dinosaur ichnospecies Apulosauripus federicianus; 3. the Cenomanian Ksar Ayaat locality, where footprints assigned to a pleurodiran turtle are exposed, and 4. the upper Cenomanian Jebel Boulouha site which presents almost 100 well-preserved tridactyl tracks referred to small-sized theropods, fossil bird tracks - ichnogenus Koreanaorins – and tracks referred to a mammalian trackmaker, representing the first report of fossil bird and mammal from the Cretaceous of continental Africa and Tunisia respectively. In addition, data collected from the Tunisian tracksites have been compared with coeval tracksites in Italy and Croatia, showing analogies in morphology and paleoenvironment of dinosaur ichnoassociations, supporting the already hypothesized subaerial connection between these areas during the mid-Cretaceous.

Genetic patterns in recovered specimens of Caretta caretta from the Adriatic Sea

The Adriatic Sea is considered a feeding and developmental area for Mediterranean loggerhead turtles, but this area is severely threatened by human impacts. In the Adriatic Sea loggerhead turtles are often found stranded or floating, but they are also recovered as by-catch from fishing activities. Nevertheless, information about population structuring and origin of individuals found in the Adriatic Sea are still limited. Cooperation with fishermen and a good network of voluntary collaborators are essential for understanding their distribution, ecology and for developing conservation strategies in the Adriatic Sea. In this study, a comparative analysis of biometric data and DNA sequence polymorphism of the long fragment of the mitochondrial control region was carried out on ninety-three loggerheads recovered from three feeding areas in the Adriatic Sea: North-western, North-eastern and South Adriatic. Differences in turtles body sizes (e.g. Straight Carapace Length) among the three recovery areas and relationship between SCL and the type of recovery were investigated. The origin of turtles from Mediterranean rookeries and the use of the Adriatic feeding habitats by loggerheads in different life-stages were assessed to understand the migratory pathway of the species. The analysis of biometric data revealed a significant difference in turtle sizes between the Southern and the Northern Adriatic. Moreover, size of captured turtles resulted significantly different from the size of stranded and floating individuals. Actually, neritic sub-adults and adults are more affected by incidental captures than juveniles because of their feeding behavior. The Bayesian mixed-stock analysis showed a strong genetic relationship between the Adriatic aggregates and Mediterranean rookeries, while a low pro¬portion of individuals of Atlantic origin were detected in the Adriatic feeding grounds. The presence of migratory pathways towards the Adriatic Sea due to the surface current system was reinforced by the finding of individuals bearing haplotypes endemic to the nesting populations of Libya, Greece and Israel. A relatively high contribution from Turkey and Cyprus to the Northwest and South Adriatic populations was identified when the three sampled areas were analyzed independently. These results have to be taken in account in a conservative perspective, since coastal hazards, affecting the population of turtles feeding in the Adriatic Sea may also affect the nesting populations of the Eastern Mediterranean with a unique genetic pattern.

Finite Element Modeling of Shell Shape in the Freshwater Turtle Pseudemys concinna Reveals a Trade-Off between Mechanical Strength and Hydrodynamic Efficiency

Aquatic species can experience different selective pressures on morphology in different flow regimes. Species inhabiting lotic regimes often adapt to these conditions by evolving low-drag (i.e., streamlined) morphologies that reduce the likelihood of dislodgment or displacement. However, hydrodynamic factors are not the only selective pressures influencing organismal morphology and shapes well suited to flow conditions may compromise performance in other roles. We investigated the possibility of morphological trade-offs in the turtle Pseudemys concinna. Individuals living in lotic environments have flatter, more streamlined shells than those living in lentic environments; however, this flatter shape may also make the shells less capable of resisting predator-induced loads. We tested the idea that ‘‘lotic’’ shell shapes are weaker than ‘‘lentic’’ shell shapes, concomitantly examining effects of sex. Geometric morphometric data were used to transform an existing finite element shell model into a series of models corresponding to the shapes of individual turtles. Models were assigned identical material properties and loaded under identical conditions, and the stresses produced by a series of eight loads were extracted to describe the strength of the shells. ‘‘Lotic’’ shell shapes produced significantly higher stresses than ‘‘lentic’’ shell shapes, indicating that the former is weaker than the latter. Females had significantly stronger shell shapes than males, although these differences were less consistent than differences between flow regimes. We conclude that, despite the potential for many-to-one mapping of shell shape onto strength, P. concinna experiences a trade-off in shell shape between hydrodynamic and mechanical performance. This trade-off may be evident in many other turtle species or any other aquatic species that also depend on a shell for defense. However, evolution of body size may provide an avenue of escape from this trade-off in some cases, as changes in size can drastically affect mechanical performance while having little effect on hydrodynamic performance.

Biomechanics on the Half Shell: Functional Performance Influences Patterns of Morphological Variation in the Emydid Turtle carapace

This study uses the carapace of emydid turtles to address hypothesized differences between terrestrial and aquatic species. Geometric morphometrics are used to quantify shell shape, and performance is estimated for two shell functions: shell strength and hydrodynamics. Aquatic turtle shells differ in shape from terrestrial turtle shells and are characterized by lower frontal areas and presumably lower drag. Terrestrial turtle shells are stronger than those of aquatic turtles; many-to-one mapping of morphology to function does not entirely mitigate a functional trade-off between mechanical strength and hydrodynamic performance. Furthermore, areas of morphospace characterized by exceptionally poor performance in either of the functions are not occupied by any emydid species. Though aquatic and terrestrial species show no significant differences in the rate of morphological evolution, aquatic species show a higher lineage density, indicative of a greater amount of convergence in their evolutionary history. The techniques employed in this study, including the modeling of theoretical shapes to assess performance in unoccupied areas of morphospace, suggest a framework for future studies of morphological variation.

Morphological and Mechanical Changes in Juvenile Red-Eared Slider Turtle (Trachemys Scripta Elegans) Shells During Ontogeny

Turtles experience numerous modifications in the morphological, physiological, and mechanical characteristics of their shells through ontogeny. Although a general picture is available of the nature of these modifications, few quantitative studies have been conducted on changes in turtle shell shape through ontogeny, and none on changes in strength or rigidity. This study investigates the morphological and mechanical changes that juvenile Trachemys scripta elegans undergo as they increase in size. Morphology and shell rigidity were quantified in a sample of 36 alcohol-preserved juvenile Trachemys scripta elegans. Morphometric information was used to create finite element models of all specimens. These models were used to assess the mechanical behavior of the shells under various loading conditions. Overall, we find that turtles experience complementary changes in size, shape, deformability, and relative strength as they grow. As turtles age their shells become larger, more elongate, relatively flatter, and more rigid. These changes are associated with decreases in relative (size independent) strength, even though the shells of larger turtles are stronger in an absolute sense. Decreased deformability is primarily due to changes in the size of the animals. Residual variation in deformability cannot be explained by changes in shell shape. This variation is more likely due to changes in the degree of connectedness of the skeletal elements in the turtle's shells, along with changes in the thickness and degree of mineralization of shell bone. We suggest that the mechanical implications of shell size, shape, and deformability may have a large impact on survivorship and development in members of this species as they mature. J. Morphol. 275:391-397, 2014. 2013 Wiley Periodicals, Inc. Copyright 2013 Wiley Periodicals, Inc.

Tolerance of human placental tissue to severe hypoxia and its relevance for dual ex vivo perfusion

In the dual ex vivo perfusion of an isolated human placental cotyledon it takes on average 20-30 min to set up stable perfusion circuits for the maternal and fetal vascular compartments. In vivo placental tissue of all species maintains a highly active metabolism and it continues to puzzle investigators how this tissue can survive 30 min of ischemia with more or less complete anoxia following expulsion of the organ from the uterus and do so without severe damage. There seem to be parallels between "depressed metabolism" seen in the fetus and the immature neonate in the peripartum period and survival strategies described in mammals with increased tolerance of severe hypoxia like hibernators in the state of torpor or deep sea diving turtles. Increased tolerance of hypoxia in both is explained by "partial metabolic arrest" in the sense of a temporary suspension of Kleiber's rule. Furthermore the fetus can react to major changes in surrounding oxygen tension by decreasing or increasing the rate of specific basal metabolism, providing protection against severe hypoxia as well as oxidative stress. There is some evidence that adaptive mechanisms allowing increased tolerance of severe hypoxia in the fetus or immature neonate can also be found in placental tissue, of which at least the villous portion is of fetal origin. A better understanding of the molecular details of reprogramming of fetal and placental tissues in late pregnancy may be of clinical relevance for an improved risk assessment of the individual fetus during the critical transition from intrauterine life to the outside and for the development of potential prophylactic measures against severe ante- or intrapartum hypoxia. Responses of the tissue to reperfusion deserve intensive study, since they may provide a rational basis for preventive measures against reperfusion injury and related oxidative stress. Modification of the handling of placental tissue during postpartum ischemia, and adaptation of the artificial reperfusion, may lead to an improvement of the ex vivo perfusion technique.

Letter from the Editor Spring/Summer 2010

Despite the horrific oil spill in the Gulf and possible extinction of Kemp's Ridley sea turtles, there are still reasons to celebrate the shore--for example, Connecticut's shorebirds.

Literature review of elasmobranch bycatch and retention rate

To address growing concern over the effects of fisheries non-target catch on elasmobranchs worldwide, the accurate reporting of elasmobranch catch is essential. This requires data on a combination of measures, including reported landings, retained and discarded non-target catch, and post-discard survival. Identification of the factors influencing discard vs. retention is needed to improve catch estimates and to determine wasteful fishing practices. To do this we compared retention rates of elasmobranch non-target catch in a broad subset of fisheries throughout the world by taxon, fishing country, and gear. A regression tree and random forest analysis indicated that taxon was the most important determinant of retention in this dataset, but all three factors together explained 59% of the variance. Estimates of total elasmobranch removals were calculated by dividing the FAO global elasmobranch landings by average retention rates and suggest that total elasmobranch removals may exceed FAO reported landings by as much as 400%. This analysis is the first effort to directly characterize global drivers of discards for elasmobranch non-target catch. Our results highlight the importance of accurate quantification of retention and discard rates to improve assessments of the potential impacts of fisheries on these species.

Mio-Pliocene crustaceans from the Canary Islands, Spain

There are few previous references to fossil crustaceans for the Neogene marine layers of the Canary Islands (Spain). The Mio-Pliocene marine sedimentary layers in the eastern islands (Gran Canaria, Fuerteventura and Lanzarote) were previously characterised by the presence of numerous fossil fauna, mainly anthozoans and molluscs, which correspond to an equatorial-typepalaeoclimate, warmer than the present climate. This Mio-Pliocene transition dated between 9.3 and 4.1 Ma. In this paper, 12 fossil crustacean taxa are identified and classified, including decapods and barnacles: Balanus concavus Bronn, 1831, Balanus spongicola Brown, 1827, Balanus perforatus Bruguière, 1789, Chenolobia testudinaria Linnè, 1767, Tetraclita cf. rubescens Darwin, 1854, Callianassa matsoni Rathbun, 1935, Callianassa sp., Upogebia sp, Eriphia aff. verrucosa (Forskal, 1775) , Maja sp., Scylla michelini Milne-Edwards, 1861 and Ocypode sp. Some of these taxa mean new references for the Atlantic islands and the North African Atlantic and definitely enlarge the palaeographic distribution of Neogene crustaceans beyond the Mediterranean region, extending it to the North Atlantic. Particularly significant are the presence of Tetraclita cf. rubescens ,this being the first reported fossil occurrence of this barnacle outside the North America Pacific coasts, and Chenolobia testudinaria , indicating for the first time the existence of marine turtles in these islands during the Neogene. These results are coherent with previous research hypothesising the existence of a flow of surface water between the Pacific and Atlantic in the Mio-Pliocene transition (Central American Seaway, CAS) which explains the arrival of organisms, in larval stage, from Central America to the Canary Islands

The nature of shield abnormalities in the turtle shell / [by] Rainer Zangerl -- and Ralph G. Johnson --.

v.10:no.29(1957)