Flegra Bentivegna

First records of dive durations for a hibernating sea turtle.

The first published record, from the early 1970s, of hibernation in sea turtles is based on the reports of the indigenous Indians and fishermen from Mexico, who hunted dormant green turtles (Chelonia mydas) in the Gulf of California. However, there were no successful attempts to investigate the biology of this particular behaviour further. Hence, data such as the exact duration and energetic requirements of dormant winter submergences are lacking. We used new satellite relay data loggers to obtain the first records of up to 7 h long dives of a loggerhead turtle (Caretta caretta) overwintering in Greek waters. These represent the longest dives ever reported for a diving marine vertebrate. There is strong evidence that the dives were aerobic, because the turtle surfaced only for short intervals and before the calculated oxygen stores were depleted. This evidence suggests that the common belief that sea turtles hibernate underwater, as some freshwater turtles do, is incorrect.

When surfacers do not dive: multiple significance of extended surface times in marine turtles

SUMMARY Marine turtles spend more than 90% of their life underwater and have been termed surfacers as opposed to divers. Nonetheless turtles have been reported occasionally to float motionless at the surface but the reasons for this behaviour are not clear. We investigated the location, timing and duration of extended surface times (ESTs) in 10 free-ranging loggerhead turtles (Caretta caretta) and the possible relationship to water temperature and diving activity recorded via satellite relay data loggers for 101–450 days. For one turtle that dived only in offshore areas, ESTs contributed 12% of the time whereas for the other turtles ESTs contributed 0.4–1.8% of the time. ESTs lasted on average 90 min but were mostly infrequent and irregular, excluding the involvement of a fundamental regulatory function. However, 82% of the ESTs occurred during daylight, mostly around noon, suggesting a dependence on solar radiation. For three turtles, there was an appreciable (7°C to 10.5°C) temperature decrease with depth for dives during periods when ESTs occurred frequently, suggesting a re-warming function of EST to compensate for decreased body temperatures, possibly to enhance digestive efficiency. A positive correlation between body mass and EST duration supported this explanation. By contrast, night-active turtles that exceeded their calculated aerobic dive limits in 7.6–16% of the dives engaged in nocturnal ESTs, probably for lactate clearance. This is the first evidence that loggerhead turtles may refrain from diving for at least two reasons, either to absorb solar radiation or to recover from anaerobic activity.

Long‐Term Cold Acclimation Leads to High Q10 Effects on Oxygen Consumption of Loggerhead Sea Turtles Caretta caretta

We monitored oxygen consumption (V̇o2, body temperatures (Tb), submersion intervals, and circadian rhythms of V̇o2 in nine loggerhead turtles during a 6‐mo period. The turtles originated from the Tyrhennian Sea, South Italy (40°51′N, 14°17′E) and were kept in indoor tanks at constant photoperiod while being subject to the seasonal decline in water temperature (Tw = 27.1° to 15.3°C). From summer to winter, all turtles underwent profound reductions in V̇o2 (Q10 = 5.4). Simultaneously, their activity was greatly reduced and submergence intervals increased. Over 24‐h periods, however, the turtles showed no circadian rhythm in activity or V̇o2. However, there was a significant positive correlation between the proportion of a day spent actively swimming and V̇o2. Tbs were not significantly different from Tw and followed the same seasonal decline. A second experiment was conducted to establish the effect of short‐term exposure to various temperatures on V̇o2. Tb equilibrated with the experimental Tw within 3 h. The metabolic responses were again positively correlated with changes in Tw , but this time the corresponding Q10 was only 1.3. On the basis of the range of body masses of the turtles used in this study (2–60 kg), the intraspecific scaling exponent for V̇o2 was 0.353.

Regional Blood Flow in Sea Turtles: Implications for Heat Exchange in an Aquatic Ectotherm

Despite substantial knowledge on thermoregulation in reptiles, the mechanisms involved in heat exchange of sea turtles have not been investigated in detail. We studied blood flow in the front flippers of two green turtles, Chelonia mydas, and four loggerhead turtles, Caretta caretta, using Doppler ultrasound to assess the importance of regional blood flow in temperature regulation. Mean blood flow velocity and heart rate were determined for the water temperature at which the turtles were acclimated (19.3°– 22.5°C) and for several experimental water temperatures (17°–32°C) to which the turtles were exposed for a short time. Flipper circulation increased with increasing water temperature, whereas during cooling, flipper circulation was greatly reduced. Heart rate was also positively correlated with water temperature; however, there were large variations between individual heart rate responses. Body temperatures, which were additionally determined for the two green turtles and six loggerhead turtles, increased faster during heating than during cooling. Heating rates were positively correlated with the difference between acclimation and experimental temperature and negatively correlated with body mass. Our data suggest that by varying circulation of the front flippers, turtles are capable of either transporting heat quickly into the body or retaining heat inside the body, depending on the prevailing thermal demands.

Helminth communities of loggerhead turtles (Caretta caretta) from Central and Western Mediterranean Sea: The importance of host's ontogeny

We investigated the factors providing structure to the helminth communities of 182 loggerhead sea turtles, Caretta caretta, collected in 6 localities from Central and Western Mediterranean. Fifteen helminth taxa (10 digeneans, 4 nematodes and 1 acanthocephalan) were identified, of which 12 were specialist to marine turtles; very low numbers of immature individuals of 3 species typical from fish or cetaceans were also found. These observations confirm the hypothesis that phylogenetic factors restrict community composition to helminth species specific to marine turtles. There were significant community dissimilarities between turtles from different localities, the overall pattern being compatible with the hypothesis that parasite communities reflect the ontogenetic shift that juvenile loggerheads undergo from oceanic to neritic habitats. The smallest turtles at the putative oceanic, pelagic-feeding stage harboured only the 2 digenean species that were regionally the most frequent, i.e. Enodiotrema megachondrus and Calycodes anthos; the largest turtles at the putative neritic, bottom-feeding stage harboured 11 helminth taxa, including 3 nematode species that were rare or absent in turtles that fed partially on pelagic prey. Mean species richness per host was low (range: 1.60-1.89) and did not differ between localities. Variance ratio tests indicated independent colonization of each helminth species. Both features are expected in ectothermic and vagrant hosts living in the marine environment.

Flow and prey capture by the scyphomedusa Phyllorhiza punctata von Lendenfeld, 1884

The mechanical basis of prey capture and behaviour of Phyllorhiza punctata von Lendenfeld, 1884, as with most members of the Order Rhizostomeae, has not been described. Free-swimming medusae were videotaped in order to quantitatively describe the feeding process of P. punctata. Kinematic data demonstrated that adult medusae were surrounded by relatively high Re (102–103) flows while swimming. Therefore, momentum dominated these flows and the motions of particles entrained in the fluid surrounding swimming P. punctata. Artemia salina nauplii entrained within these flows contacted two principle capture surfaces: the oral arm cylinder and the underside of the subumbrellar surface. Prey were ingested by small polyp-like mouthlets located on these surfaces. Ingestion followed capture at these sites. P. punctata’s body morphology is highly modified to channel flows into these capture surfaces and feeding is dependent upon this pattern. Swimming activity, and hence the creation of flows used for prey capture, is continuous, as is feeding, and plays a central role in this medusa’s foraging behaviour.

Inclusion bodies in loggerhead erythrocytes are associated with unstable hemoglobin and resemble human Heinz bodies

The aim of this study was to clarify the role of the erythrocyte inclusions found during the hematological screening of loggerhead population of the Mediterranean Sea. We studied the erythrocyte inclusions in blood specimens collected from six juvenile and nine adult specimens of the loggerhead turtle, Caretta caretta, from the Adriatic and Tyrrhenian Seas. Our study indicates that the percentage of mature erythrocytes containing inclusions ranged from 3 to 82%. Each erythrocyte contained only one round inclusion body. Inclusion bodies stained with May Grünwald-Giemsa show that their cytochemical and ultrastructure characteristics are identical to those of human Heinz bodies. Because Heinz bodies originate from the precipitation of unstable hemoglobin (Hb) and cause globular osmotic resistance to increase, we analyzed loggerhead Hb using electrophoresis and high-performance liquid chromatography to detect and quantitate Hb fractions. We also tested the resistance of Hb to alkaline pH, heat, isopropanol denaturation, and globular osmosis. Our hemogram results excluded the occurrence of any infection, which could be associated with an inclusion body, in all the specimens. Negative Feulgen staining indicated that the inclusion bodies are not derived from DNA fragmentation. We hypothesize that amino acid substitutions could explain why loggerhead Hb precipitates under normal physiologic conditions, forming Heinz bodies. The identification of inclusion bodies in loggerhead erythrocytes allow us to better understand the haematological characteristics and the physiology of these ancient reptiles, thus aiding efforts to conserve such an endangered species.

Northward spread of tropical affinity fishes: Caranx crysos (Teleostea: Carangidae), a case study from the Mediterranean Sea

Abstract The blue runner Caranx crysos is a thermophilic species poorly investigated in the Mediterranean Sea. Although considered a typical inhabitant of the southern regions, it has recently established in northwest Sicily and, according to the data presented in this study, is now regularly caught in the central-southern Tyrrhenian Sea up to the Gulf of Naples. Some occurrences of the species were also documented in the Gulf of Taranto (Ionian Sea) and in more northerly localities of the Tyrrhenian Sea, such as Gaeta and Civitavecchia. These recent distributional records are in contrast with historical literature and museum collections which depict this species as very rare in the Italian seas and only sporadically occurring above the Strait of Sicily. In this paper, literature and museum collections were thoroughly investigated in order to obtain a satisfactory understanding of the species distribution in the Mediterranean. In addition, the hypothesis of a recent displacement of the northern limit of this species distributional range in the Mediterranean is discussed.

The first report of a loggerhead turtle Caretta caretta nest on the central Tyrrhenian coast (western Mediterranean)

Here we report for the first time on a loggerhead turtle, Caretta caretta, which laid 92 eggs on the south-west Italian coast on 11 July 2002. During the 64 day incubation period the nest was threatened by inundation and hence, it was transferred on the 28th day. The hatching success was 49.4% and all live hatchlings entered the sea. Unhatched eggs were opened to determine at which developmental stage embryonic death occurred. This analysis confirmed that most of the embryos died in the first few days after laying and that the transfer of the nest did not affect embryonic development. This was the third of three unusual nesting events in the western Mediterranean in the years 2001–2002.

Hemoparasitization by Theileria in the loggerheads Caretta caretta of the Mediterranean Sea

Theileria is a small Apicomplexan parasite considered as the scourge of the cattle industry, here detected for the first time in the blood cells of Caretta caretta from the Mediterranean Sea. In the early stage of infection by Theileria, rounded forms, defined schizonts, occur in lymphocytes and heterophils. After lysis of these leukocytes, the schizonts shift into plasmatic rounded free forms named merozoites. The latter enter the erythrocytes producing two, three, or four bacilliform daughter cells and curved forms similar to trophozoites and sometimes larger crescent-shaped forms similar to gametocytes. The differential recognition of Babesia, which is also a member of the Theileriidae versus Theileria is based on observing the early stages of Theileria in leukocytes, which Babesia is not parasitic. Infestations of Theileria are first recognized in loggerheads by their presence in leukocytes.