Observations about surface behaviour of the great white shark Carcharodon carcharias (L.) in presence of passive preys at Dyer Island (Southafrica)

During 4 study expeditions in SouthAfrica, performed in 2000, 2003, 2004 and 2005, observations about surface predatory behaviour of the Great White Shark in presence of passive preys were made. Observations were carried out by Unlimited Shark Diving boats and by cage diving around Dyer Island, about 5 miles far from Gansbaai. During the 27 observation days were identified 78 different specimens, that exhibited 8 different behaviours. The Great White Shark population observed around Dyer island shows a greater variety of behaviours than the population studied along the California coasts

Morphometric maps of bilateral asymmetry in the human humerus: An implementation in the R package morphomap

In biological anthropology, parameters relating to cross-sectional geometry are calculated in paired long bones to evaluate the degree of lateralization of anatomy and, by inference, function. Here, we describe a novel approach, newly added to the morphomap R package, to assess the lateralization of the distribution of cortical bone along the entire diaphysis. The sample comprises paired long bones belonging to 51 individuals (10 females and 41 males) from The New Mexico Decedent Image Database with known biological profile, occupational and loading histories. Both males and females show a pattern of right lateralization. In addition, males are more lateralized than females, whereas there is not a significant association between lateralization with occupation and loading history. Body weight, height and long-bone length are the major factors driving the emergence of asymmetry in the humerus, while interestingly, the degree of lateralization decreases in the oldest individuals

Analysis of sightings of white sharks in Gansbaai (South Africa)

In Gansbaai (South Africa), at Dyer Island Nature Reserve, a large White shark population is present and can be observed due to the support of local ecotourism operators authorised to reach the field observation sites. Between 2009 and 2019, it was possible to create a database including information about each individual observed. In total, 423 white sharks were sighted during 462 direct observation hours from the boat, that included 220 hours from the diving "cage". The mean sighting rate was 0.91 (range 0.18-1.53) sharks per hour and sighting rates dramatically declined in the last three years of the study period. Ninety-nine unique Photo-Ids of the dorsal fin were collected and only five re-sightings occurred, which indicate a transient behaviour for the Gansbaai White shark population. The sex ratio showed that females were always prevalent over males throughout the duration of the observations: the ratios were 1:2.2:0.8 for males, females, and unsexed sharks, respectively, and showed the prevalence of immature female individuals (immature: 51 males, 201 females, and 40 unsexed; adults: 49 males, 14 females, and 1 unsexed; undefined maturity: 5 males, 19 females, and 43 unsexed sharks). The predominance of immatures only applies to the females; there were as many immature males (51) as mature (49). The total length for all the individuals was between 150 cm and 500 cm (mean 308 cm, n = 423) with few young-of-the-year and adults recorded, indicating that Gansbaai Area is not a nursery area nor an adult aggregation site, but a seasonal feeding ground. The interannual sighting trend showed a consistent long-term increasing peak (ca. 4-5 years) and this could confirm that, in Gansbaai, the White shark frequency is not affected by ecotourism but, since 2017, a consistent loss of sightings was also due to recorded transient killer whales' unusual fatal attacks

Strontium and oxygen isotopes as indicators of Longobards mobility in Italy: an investigation at Povegliano Veronese

The arrival of the Longobards in Northern Italy in 568 CE marked a period of renewed political stability in the Peninsula after the collapse of the Western Roman Empire. The trajectory of the spread of Longobards in Italy across the Alps and into the South is known from many literary sources. However, their mobility and residence patterns at a population level remain to be fully understood. Here we present a multi-isotopic analysis (87Sr/86Sr and 18O/16O) of 39 humans and 14 animals buried at the Longobard necropolis of Povegliano Veronese (VR, Italy; 6th—8th century CE), to address mode and tempo of the spread of this population in the Peninsula. The geographical location of Povegliano Veronese plays a key role: the site lies along the Via Postumia, which was one of the main ancient Roman roads of Northern Italy, representing an important route in post-classical Italy. The integration of isotopic data with the archaeological evidence allowed us to determine the presence of individuals from at least three different regions of origin, building a diachronic map of the dynamics of mobility of this group in northern Italy

Trace elements and isotopes analyses on historical samples of white sharks from the Mediterranean Sea

The white shark Carcharodon carcharias has been present in the Mediterranean Sea since 3.2 million years ago. Nevertheless, the current population shows a low genetic variability suggesting an endangered small population, on which there is scarce information regarding ecotoxicology or trophic ecology. Given that white shark's sightings are rare in the Mediterranean and the possibility of obtaining samples is highly limited, the aim of this research was to provide general information regarding the concentration of trace elements and stable isotopes (delta N-15 and delta C-13). Laboratory analyses were performed on 18 and 12 subsamples from two different white sharks' vertebrae obtained from two adult specimens caught in 1987, in Favignana Island, Italy. Perforations were made along the vertebrae to describe both trace elements and stable isotopes at different life stages. A total of 38 trace elements were analysed, in which the highest concentrations were found in Fe, Sr, U, Pb, and Zn. The fluctuations of these elements during the ontogeny of both individuals could have been related to changes in diet and environment, although the specific origin remains unknown. Regarding stable isotopes, the vertebrae from the male showed an isotopic range from 9.6 parts per thousand to 10.8 parts per thousand (delta N-15) and from -16.5 parts per thousand to -13.0 parts per thousand (delta C-13) with a mean +/- SD value of 10.3 +/- 0.4 parts per thousand for delta N-15 and -14.6 +/- 1.3 parts per thousand for delta C-13; whereas the female vertebrae had an isotopic range from 9.8 parts per thousand to 11.1 parts per thousand (delta N-15) and from -16.9 parts per thousand to -15.0 parts per thousand (delta C-13), with a mean +/- SD value of 10.8 +/- 0.6 parts per thousand for delta N-15 and -15.8 +/- 0.8 parts per thousand for delta C-13. There were no significant delta N-15 differences (U = 6, p = 0.07346) between the two individuals. However, there were just significant differences in delta C-13 (t = -1.8, p = 0.049256), which could suggest sexual segregation in terms of habitat use and feeding habits

Pliocene colonization of the Mediterranean by Great White Shark inferred from fossil records, historical jaws, phylogeographic and divergence time analyses

Aim: Determine the evolutionary origin of the heretofore poorly characterized contemporary Great White Shark (GWS; Carcharodon carcharias) of the Mediterranean Sea, using phylogenetic and dispersal vicariance analyses to trace back its global palaeo-migration pattern. Location: Mediterranean Sea. Taxon: Carcharodon carcharias. Methods: We have built the largest mitochondrial DNA control region (CR) sequence dataset for the Mediterranean GWS from referenced historical jaws spanning the 19th and 20th centuries. Mediterranean and global GWS CR sequences were analysed for genetic diversity, phylogenetic relationships and divergence time. A Bayes factor approach was used to assess two scenarios of GWS lineage divergence and emergence of the Mediterranean GWS line using fossil records and palaeo-geographical events for calibration of the molecular clock. Results: The results confirmed a closer evolutionary relationship between Mediterranean GWS and populations from Australia–New Zealand and the North-eastern Pacific coast rather than populations from South African and North-western Atlantic. The Mediterranean GWS lineage showed the lowest genetic diversity at the global level, indicating its recent evolutionary origin. An evaluation of various divergence scenarios determined the Mediterranean GWS lineage most likely appeared some 3.23 million years ago by way dispersal/vicariance from Australian/Pacific palaeo-populations. Main conclusion: Based on the fossil records, phylogeographic patterns and divergence time, we revealed that the Mediterranean GWS population originated in the Pliocene following the Messinian Salinity Crisis. Colonization of the Mediterranean by GWS likely occurred via an eastward palaeo-migration of Australian/eastern Pacific elements through the Central American Seaway, before the complete closure of the Isthmus of Panama. This Pliocene origin scenario contrasts with a previously proposed scenario in which Australian GWS colonized the Mediterranean via antipodean northward migration resulting from navigational errors from South Africa during Quaternary climatic oscillations

New Mediterranean Marine biodiversity records

Based on recent biodiversity studies carried out in different parts of the Mediterranean, the following 19 species are included as new records on the floral or faunal lists of the relevant ecosystems: the green algae Penicillus capitatus (Maltese waters); the nemertean Amphiporus allucens (Iberian Peninsula, Spain); the salp Salpa maxima (Syria); the opistobranchs Felimida britoi and Berghia coerulescens (Aegean Sea, Greece); the dusky shark Carcharhinus obscurus (central-west Mediterranean and Ionian Sea, Italy); Randall’s threadfin bream Nemipterus randalli, the broadbanded cardinalfish Apogon fasciatus and the goby Gobius kolombatovici (Aegean Sea, Turkey); the reticulated leatherjack Stephanolepis diaspros and the halacarid Agaue chevreuxi (Sea of Marmara, Turkey); the slimy liagora Ganonema farinosum, the yellowstripe barracuda Sphyraena chrysotaenia, the rayed pearl oyster Pinctada imbricata radiata and the Persian conch Conomurex persicus (south-eastern Kriti, Greece); the blenny Microlipophrys dalmatinus and the bastard grunt Pomadasys incisus (Ionian Sea, Italy); the brown shrimp Farfantepenaeus aztecus (north-eastern Levant, Turkey); the blue-crab Callinectes sapidus (Corfu, Ionian Sea, Greece). In addition, the findings of the following rare species improve currently available biogeographical knowledge: the oceanic pufferfish Lagocephalus lagocephalus (Malta); the yellow sea chub Kyphosus incisor (Almuñécar coast of Spain); the basking shark Cetorhinus maximus and the shortfin mako Isurus oxyrinchus (north-eastern Levant, Turkey)

Time-Sensitive User Profile for Optimizing Search Personlization

International audienceThanks to social Web services, Web search engines have the opportunity to afford personalized search results that better fit the user’s information needs and interests. To achieve this goal, many personalized search approaches explore user’s social Web interactions to extract his preferences and interests, and use them to model his profile. In our approach, the user profile is implicitly represented as a vector of weighted terms which correspond to the user’s interests extracted from his online social activities. As the user interests may change over time, we propose to weight profiles terms not only according to the content of these activities but also by considering the freshness. More precisely, the weights are adjusted with a temporal feature. In order to evaluate our approach, we model the user profile according to data collected from Twitter. Then, we rerank initial search results accurately to the user profile. Moreover, we proved the significance of adding a temporal feature by comparing our method with baselines models that does not consider the user profile dynamics

MEDLEM database, a data collection on large elasmobranchs in the Mediterranean and Black Seas

The Mediterranean Large Elasmobranchs Monitoring (MEDLEM) database contains more than 3,000 records (with more than 4,000 individuals) of large elasmobranch species from 21 different countries around the Mediterranean and Black seas, observed from 1666 to 2017. The principal species included in the archive are the devil ray (1,868 individuals), the basking shark (935 individuals), the blue shark (622 individuals), and the great white shark (342 individuals). In the last decades, other species such as the thresher shark (187 individuals), the shortfin mako (180 individuals), and the spiny butterfly ray (138) were reported with increasing frequency. This was possibly due to increased public awareness on the conservation status of sharks, and the consequent development of new monitoring programs. MEDLEM does not have homogeneous reporting coverage throughout the Mediterranean and Black seas and it should be considered as a database of observed species presence. Scientific monitoring efforts in the south-eastern Mediterranean and Black seas are generally lower than in the northern sectors and the absence of some species in our database does not imply their actual absence in these regions. However, the available data allowed us to analyse the frequency and spatial distribution of records, the size frequencies for a few selected the available data allowed us to analyse the frequency and spatial distribution of records, the size frequencies for a few selected species, the overall area coverage, and which species are involved as bycatch by different fishing gears