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Sea turtles are known for a long time as a habitat for numerous and diverse microbes that happily live on the external and internal surfaces of their different body parts. Shells are especially known to be often covered with various macroepibionts and colourful biofilms formed by diatoms and bacteria. These microbes can be specialized and found almost exclusively associated with sea turtles but also opportunistic and found elsewhere in the turtle environment. In this presentation I am going to show you an overview of results obtained by research conducted within the TurtleBIOME project running in the period of 2018-2023 that involved a lot of very enthusiastic and dedicated participants and we are extremely thankful for their involvement. The main focus of our research was to characterize the microbial communities found in both the external (skin and shell) and the internal (gut, cloaca, oral cavities) habitats provided by loggerheads. We chose this species of sea turtle (Caretta caretta) as it is the most common turtle species in the Mediterranean Sea. We collected microbial samples from >120 animals from several locations in the Mediterranean area (Pula, Vis, and Lošinj in Croatia, Bari in Italy, and Amvrakikos Bay and Rethymnos in Greece) and analysed them using amplicon profiling with 16S, 18S, rbcL and ITS as molecular markers. The collected carapace and skin biofilm samples were also analysed using classical microscopical approach and that resulted in the description of several new diatom species. We have also isolated, identified, and maintained ca. 200 non-axenic diatom strains, which were then used in several experiments investigating the ecological preferences of diatoms themselves and their associated bacterial partners. We characterized the bacterial community of turtle-associated diatoms using metabarcoding and cultivation approach. This presentation will summarize these and other results we obtained while exploring the prokaryotic and microeukaryotic communities of loggerheads. Our multidisciplinary investigations provide the first inventory of loggerhead sea turtle endo- and epimicrobiota, revealing high diversity, different levels of host fidelity, and local biogeography of sea turtle associated microbes. more...

Sea turtles provide an excellent habitat for diverse community of specialized and opportunistic microbes. We collected microbial samples from 126 animals from several locations in the Mediterranean: Pula, Vis, and Lošinj in Croatia, Bari and Naples (ASSEMBLE Plus TA, SZN) in Italy, and Amvrakikos Bay and Rethymnos in Greece. Among others, the collected carapace and skin biofilm samples contained new species of microalgae (diatoms) We have isolated, identified, and maintained ca. 200 non-axenic diatom strains, which were then used in several experiments. We also characterized the bacterial community using metabarcoding and cultivation approach (ASSEMBLE Plus TA Uni Ghent, Belgium). This presentation will summarize these and other results we obtained while exploring the prokaryotic and microeukaryotic communities of loggerheads. more...

Sea turtles suffer from numerous threats such as predation, tidal inundation, and coastal building. We aimed to assess the effectiveness of hatchery technique on Göksu Delta beach, Turkey during the nesting season of 2010. For this purpose, eggs of loggerhead turtle (Caretta caretta) nests under the risk of tidal inundation were transferred into two protected hatchery sites that were constructed on Göksu Delta beach, in which there were no risk of predation and inundation, and the other nests were left to remain in situ. Hatching success of hatchery and natural nests were calculated. In addition, temperatures of both hatchery and natural nests (5 and 6 nests, respectively) were recorded, and sex ratios were determined using these nest temperatures and incubation periods. It was determined that hatching success increased with increasing distance from the sea (until 31 m) (r2 = 0.98), increasing incubation period (up to 60 days) (r2 = 0.68), and decreasing clutch size (r2 = 0.93), implying that the production of male hatchling is high in a nest if hatching success of that nest is high (or vice versa). Mean hatching success, incubation period, and nest temperature for hatchery nests were found to be 72.8%, 51.1 days, and 30.2 °C, respectively, while the corresponding values for natural nests were found to be 40.5%, 49.9 days, and 31.1 °C, respectively. It was also detected that hatchery nests produced higher proportion of male hatchlings (25.2%) compared with natural nests (13.5%). Based on all these results, it can be concluded that hatchery management on this beach is not a completely effective conservation technique. Nest relocation and/or hatchery management enable the conservationists to increase hatching success rate, but they cause sex ratio alteration. In this respect, we can only partially support nest relocation and/or hatchery management. They should be considered as a last option due to sex ratio alteration. © 2017 Elsevier Ltd more...

With the aim of evaluating the presence of Fusarium spp. in sea turtles with and without lesions and assessing the risk factors favoring colonization and/or infection, 74 loggerhead sea turtles ( Caretta caretta) admitted to rescue and rehabilitation clinics in Italy were analyzed. The study compared 31 individuals with no apparent macroscopic lesions and 43 individuals with macroscopic lesions. Shell and skin samples were analyzed using Calcofluor white with 10% potassium hydroxide, standard histopathological examination, and fungal cultures. Fusarium spp. were isolated more frequently from animals with superficial lesions (39%) than from those with no macroscopic lesions (16%). Isolates from animals with superficial lesions were Fusarium solani species complex (FSSC) lineages haplotypes 9, 12, and 27 (unnamed lineages), FSSC-2 ( Fusarium keratoplasticum), Fusarium oxysporum (27%), and Fusarium brachygibbosum (3%). In contrast, only F. solani haplotypes 9 and 12 were isolated from animals with no macroscopic lesions. The presence of lesions was identified as a risk factor for the occurrence of Fusarium spp. Of the 74 animals, only 7 (9.5%) scored positive on microscopic examination with Calcofluor, and histological examination of those 7 animals revealed necrosis, inflammatory cells, and fungal hyphae in the carapace and skin. The results of this study suggest that fusariosis should be included in the differential diagnosis of shell and skin lesions in sea turtles. Direct examination using Calcofluor and potassium hydroxide was not useful to diagnose the infection. Histopathological examination and fungal culture should be performed to ensure correct treatment and infection control. more...

Epizoic diatoms form an important part of micro-epibiota of marine vertebrates such as whales and sea turtles. The present study explores and compares the diversity and biogeography of diatom communities growing on the skin and shell of loggerhead sea turtles (Caretta caretta) from four different localities: Adriatic Sea (Croatia), Ionian Sea (Greece), South Africa and Florida Bay (USA) using both light and scanning electron microscopy. We observed almost 400 diatom taxa belonging to more than 100 genera. Diatom communities from Greece and Croatia showed the highest similarity and were statistically different from those recorded from South Africa and Florida. Part of this variation could be attributed to differences in sampling techniques; however, we believe that geography had an important role. In general, contrary to several previous observations from sea turtles, the presumably exclusively epizoic diatoms contributed less than common benthic taxa to the total diatom flora, which might have been related to the loggerhead feeding behavior. Moreover, skin samples differed from carapace samples in having a distinct diatom composition with a higher proportion of the putative true epizoonts. Our results indicate that epizoic diatom communities differ according to loggerhead geographical location and substrate (skin vs. carapace). The relative abundances of common benthic diatoms and putative exclusive epizoic taxa may inform about sea turtle habitat use or behavior though detailed comparisons among different host species have yet to be performed. more...

Although the first report of epizoic diatoms on cetaceans dates back to 1920, it is only since recent years that the micro-epibiotic communities on sea turtles receive scientific interest. This thesis investigated the epibiotic diatom communities associated with the carapace and skin of loggerhead sea turtles (Caretta caretta) from four geographically different populations: Amvrakikos Bay (Greece), Florida Bay (USA), Adriatic Sea (Croatia) and Kosi Bay (South Africa). Samples were collected using non-harmful methods and analysed using light microscopy and scanning electron microscopy. Five carapace samples from every locality and five skin samples from Greece were analysed. Four hundred-one taxa belonging to 102 genera were observed in 24 samples. Forty-one percent of the taxa was identified to species level. The samples from Florida were the least diverse of the carapace samples. The samples from South Africa had the highest number of taxa and the samples from Greece had the highest Shannon-Wiener diversity index and evenness. The samples from Greece and Croatia showed the highest similarity. The skin samples are less taxon rich than the carapace samples. Detrended correspondence analysis showed clustering, corresponding with the sampling localities. Principal component analysis showed skin and carapace samples clustering separately. Some typical epizoic genera were observed, such as Medlinella, Chelonicola and Poulinea. The epizoic abundance varied between loggerhead populations. Several undescribed taxa were observed, of which some are in the process of being published as species being new to science. It can be concluded that loggerheads contain a high diatom diversity, of which some presumably exclusively epizoic taxa, but the majority are likely opportunistic taxa able to thrive on both biotic and abiotic substrata. Loggerheads from different populations are dominated by different diatom taxa and there appears to be a difference between the epizoic communities living on the skin and carapace of these sea turtles. more...

The diatom genus Craspedostauros E.J.Cox (Cox 1999) currently comprises eleven, predominantly marine species. Craspedostauros taxa have been recorded from various habitats including Antarctic saline lakes, Red Sea plankton and diverse marine benthic environments worldwide. Morphological characteristics of the genus include a stauros narrower than the fascia, cells constricted at the center in girdle view, multiple narrow double-perforated girdle bands, cribrate areolae with four to many pores, and two H-shaped chloroplasts. Recently, a new species C. alatus Majewska & Ashworth (Majewska et al. 2018) was described from carapace samples of carcasses of Kemp’s ridley and green turtle, and a morphologically similar strain CCMP1120 was found in the UTEX culture collection isolated back in 1967 from the equatorial Pacific. During the survey of the diatom assemblages found on carapaces of sea turtles from the Adriatic Sea and Kosi Bay (eastern coast of South Africa) we observed several populations of four distinct Craspedostauros taxa. Specimens from the first population found on Adriatic loggerheads morphologically correspond to epizoic C. alatus in having the external wing-like structures near the valve apices and an elongated, weakly constricted rectelevatum. In addition, based on detailed SEM and LM observations of wild populations and cultivated strains we distinguish three new species, two of them from loggerhead carapaces and one found on leatherback-associated barnacles, Platylepas coriacea. The first unknown taxon has centrally constricted valves, irregularly shaped areolae with 2-6 cribrate pores, a rectelevatum with a central distinct silica knob and multiple rows of pores around the valve apex. The second loggerhead-associated taxon also possesses a central silica knob on a rectelevatum, but has square areolae with four cribrate pores and lip-like silica flaps covering the central raphe endings. The third taxon was found on epibiotic barnacles on leatherback turtles and possesses narrow linear valves and lacks the stauros resembling C. paradoxa Ashworth & Lobban – the first Craspedostauros with strongly reduced stauros. Our findings confirm that Craspedostauros taxa are not uncommon component of the sea turtle diatom flora. Currently, however, it is still uncertain whether these taxa prefer animal substrate or attach to the sea turtle carapace and barnacles opportunistically. more...

In recent years, there is a growing scientific interest in epibiotic communities on sea turtles. A broad array of animals such as crustaceans, annelids, molluscs and macroalgae are known to thrive successfully as macro- epibionts on the sea turtle body surfaces. Together with these macroscopic organisms, sea turtles also host unique and diverse micro- epibiotic diatom communities composed of a large number of genera, several of which that have been described as new to science in the past five years. Typical examples include the genera Chelonicola, Medlinella and Poulinea, known exclusively from the carapaces and skin of different marine turtle species (Majewska et al. 2015, Frankovich et al. 2016). During a survey of the diatom flora associated with the carapaces of loggerhead sea turtles (Caretta caretta) from the Adriatic Sea, a fairly diverse diatom assemblage was observed composed of several Diploneis, Fallacia and Amphora taxa together with three unknown diatom taxa that initially could not be identified even on genus level. For at least two of them, further analysis revealed that they most likely represent new genera whereas a third one could be assigned to the genus Catenula. A first unknown taxon belongs to the monoraphid diatoms based on the presence of both a raphe and rapheless valve. The rapheless valve is characterized by the presence of a large silica crest surrounding the entire valve and covering part of the valve margin. The striae consist of two large areolae, separated by a broad hyaline plate and covered externally by porous hymenes. The raphe is rather simple with bent terminal fissures and straight, simple central endings. Comparison with achnanthoid genera such as Scalariella, Kolbesia and Madinithidium yielded both clear similarities but also distinct differences (Desrosiers et al. 2014, Riaux- Gobin et al.2012). The second unknown taxon shows similarities to the members of the genera Nitzschia, Rhopalodia and Psammodictyon based on the presence of an eccentric raphe, distinct fibulae and a dorsiventral valve outline. Finally, the third taxon is most likely a new Catenula species, a small amphoroid genus with only marginal striae, a very simple raphe structure and non-perforated, narrow girdle bands. These observations show the special nature of the epibiotic flora found on loggerheads and confirm our lack of taxonomic knowledge increasing the importance of the currently ongoing research investigating microepibiotic assemblages associated with sea turtles. more...

In recent years, there is a growing scientific interest in epibiotic communities. Sea turtles host unique and diverse diatom communities composed of a large number of genera, several of which recently described as new to science such as Chelonicola, Medlinella and Poulinea, all known almost exclusively from the carapaces and skin of marine turtle species and other marine vertebrates (Majewska et al. 2015, Frankovich et al. 2016). During a survey of the epizoic diatom flora on carapaces of loggerhead sea turtles (Caretta caretta) from the Adriatic Sea, four unknown diatom taxa were discovered on the carapace of one turtle For at least two of them, further analysis revealed that they most likely represent two new genera whereas the third and fourth taxon could be assigned to the genera Catenula and Planothidium respectively. These observations show the special nature of the epizoic diatom flora on loggerhead turtles and confirm our lack of taxonomic knowledge increasing the importance of the currently ongoing project. A first unknown taxon belongs to the monoraphid diatoms. The rapheless valve is characterized by the presence of a large silica crest surrounding the entire valve and covering part of the valve margin. The striae consist of two large areolae, separated by a broad hyaline plate and covered externally by porous hymenes. The raphe is rather simple with bent terminal fissures and simple, straight central endings. Comparison with achnanthoid genera such as Scalariella, Kolbesia and Madinithidium yielded both clear similarities but also distinct differences (Desrosiers et al. 2014, Riaux-Gobin et al. 2012). The second unknown taxon shows similarities to the genera Nitzschia, Rhopalodia and Psammodictyon based on the presence of an eccentric raphe, distinct fibulae forming a fibular plate and a dorsiventral valve outline. The third taxon is most likely a new Catenula species, a small amphoroid genus with only marginal striae, a very simple raphe structure and non-perforated, narrow girdle bands. Finally, the fourth taxon clearly belongs to the genus Planothidium showing uniseriate striae on the rapheless valve and distinct, shallow depressions in the axial area. more...

Loggerhead turtles (Caretta caretta) are primarily open-ocean animals that visit shallow coastal areas only for nesting. The geographic distribution and behavior of the species are strongly related to water temperature, food availability and oceanic currents. The turtle carapaces include a surface biofilm that serves as a habitat for epibiontic microorganisms such as bacteria and unicellular protists with diatoms being prominent in the assemblage. Research on diatom commensals on loggerhead turtle carapaces can provide interesting information on environments visited and general migration routes of the turtles. Mucilage stalks of the diatoms enable attachment to the carapace, but diatoms may also live inside mucilaginous tubes e.g. Parlibellus sp., or embed cells in mucilage matrix developed on the carapace surface. However, numerous diatoms simply inhabit the microbial EPS (extracellular polymeric substance) mixed with the mineral particles and form a distinct biofilm over the carapace. Here presented are results of a research on biofilm collected from Dalyan Beach region in Aegean Sea coast of SW Turkey during 2014 – 2018. The Dalyan Beach is considered one of the important Mediterranean nesting grounds for C. caretta. In 2016, a few pilot samples have been collected from C. caretta carapaces from Adriatic Sea (Croatia), the migration route for this species. Numerous diatoms, principally small pennate species, were isolated from biofilm into culture principally belonging in Navicula, Nitzschia, Diploneis, Halamphora, Entomoneis, Amphora and one centric Melosira sp. The true epibionts isolated in culture were few and involved stalked Achnanthes spp. and tube-dwelling Parlibellus spp. Identification of diatoms has principally been based on LM and SEM analyses of cleaned material. Diatoms in clonal cultures isolated from the C. caretta biofilm provided DNA that has been sequenced. A combined morphology (LM, SEM) and molecular markers (SSU, psbC, rbcL) establish a data base on a few dozens of taxa living in the C. caretta carapace biofilm. The spatial and temporal (sampling year) diversity of the diatom assemblages have been tested with multivariate analysis and multimetric ordination analysis (nonparametric multidimensional scaling – MDS). more...

Sea turtles which are brought to the Marine Turtle Rescue Centre Pula are being treated until full recovery and release back into the wild. Knowing turtles’ anatomy and physiology is essential for proper treating of sick animals, and one of the useful tool in assessing physiological and healthily condition of the animal is hematology. Because of the differences in hematological parameters between various species of marine turtles as well as the great impact of many intrinsic and extrinsic factors on reptilian hemogram every information on hematology of this species is valuable. Eleven Loggerhead turtles (nine adults and two juveniles) were admitted at Centre at the beginning of 2017 and 2018, because of cold stunning and entanglement in fishing nets. All animals underwent clinical examination and blood sample collection for hematological and biochemical evaluation. All animals stayed in the Centre from 2-7 months. The blood was taken two times: upon the arrival to the Centre and one day before the release into the sea. The blood analysis included: packed cell volume (PCV), red blood cell count (RBC), differential white blood cell count and morphological assessment of blood cells. Results showed higher mean (± SD) PCV 37.2% (±7.1) upon the arrival then before releasing 34.3% (±5.3), although the difference was not statistically significant. Heterophils were significantly higher at first sampling 67.5% (±12.0) comparing to the second one 55% (±7.7). There were no signs of left shift. There was a large number of polychromatophils in two juvenile turtles. Slightly higher, but not significantly, PCV values at the acceptance to the Centre were most likely because of the dehydration. Heterophils relative count decreased after rehabilitation which confirmed the correct treatment of the animals. These results will benefit further researchers in better understanding of physiological and pathophysiological variations of hematological parameters in Loggerhead turtles. more...

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-07T14:47:15Z No. of bitstreams: 1 Dissertacao Gleici Montanini FINAL.pdf: 1266315 bytes, checksum: 0fb70d1b78ff6a6d5ddd143ef64d68b7 (MD5) Made available in DSpace on 2021-01-07T14:47:15Z (GMT). No. of bitstreams: 1 Dissertacao Gleici Montanini FINAL.pdf: 1266315 bytes, checksum: 0fb70d1b78ff6a6d5ddd143ef64d68b7 (MD5) Previous issue date: 2016-06-07 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior The measurement of stable isotope is a tool that can be used in addition to feeding ecology analyzes, since the isotope composition of a predator is directly related to their prey by a diet incorporated over time. The aim of this study was to analyze the trophic relationship of sea turtle Caretta caretta with preys consumed on the coast of Paraná and observe the differences in feeding of juveniles and adults, by the analysis of carbon and nitrogen stable isotopes. Organisms at the base of the food web (seston) were collected besides, 19 species of prey (n = 94 specimens) which included mollusks, crustaceans and teleost fish, and 20 specimens of C. caretta turtles found stranded dead in the coastal beaches of Paraná (12 juveniles and 8 adults). We have analyzed the isotope ratios of carbon and nitrogen in aliquots of muscle tissue of turtles and its preys. For the carbon isotope ratio, mollusks showed values between -16.9 and -13.7 , the teleost fishes values between -27 and -15 , crustaceans between -18.8 and -15.5 and C. caretta values between -19.5 and -16.0 . As for the nitrogen isotope ratio, mollusks showed values between 10.3 and 13.9 , teleost fishes between 8.9 and 14.8 , crustaceans between 9.5 and 14.3 and turtles between 9.9 and 18.3 . Separating the turtles by maturity class, the juveniles showed mean values of -18.4 and 12.9 and adults of -16.8 and 16.2 for the carbon and nitrogen ratios, respectively. The mollusks species showed carbon stable ratio values higher than turtles, indicating that they could not be a direct prey species, therefore, raised the hypothesis that were predated hermit crabs when they used the empty mollusks shells. The results of carbon and nitrogen isotope ratios indicate the teleost fish as important prey, corroborating with the findings in other studies. With respect to maturity classes, the values for the two isotope ratios tended to increase with increasing the curved carapace length. It found a significant difference in values between juveniles and adults, for both isotope ratios, showing that feed on different prey (Student's t test, p more...