Assessing thornback ray growth pattern in different areas of Western-Central Mediterranean Sea through a Multi-Model Inference analysis

The lack of information on age validation often affects ageing studies in cartilaginous fish, even in the most common species. Recently, the annual growth band deposition pattern has been directly validated for thornback ray in the Mediterranean Basin, thus providing a highly reliable protocol for age reading. In this regard, taking advantage of this new information, the present study aims to investigate this species growth for the first time over a wide area of the Western and Central Mediterranean Sea, involving four different FAO geographic sub-areas. In order to provide an accurate description of the species growth, different models were fitted to the age-length data obtained from the observation of vertebral centra thin sections. A total of 720 specimens were analysed (358 females and 362 males) with total length ranging between 11.5 and 86.4 cm. The corrected Akaike's Information criterion (AICc) indicated, among the tested models, the three-parameter von Bertalanffy function as the most robust in describing the species growth. Growth modelling outcomes revealed the thornback rays as capable of growing relatively fast during the first years; the growth rate gradually slows down allowing maximum sizes of about 90–100 cm in total length to be reached. Significant discrepancies in the growth pattern were found between sexes in all investigated areas with the only exception being in the Northern Tyrrhenian Sea. Differences in growth patterns were observed between areas, specifically in the estimated growth rate of the species for each sub-region. The present study, confirmed the importance of the availability of a validated ageing protocol and testing multiple growth models. Moreover, our results highlighted the urgent need to investigate a species growth in a wide geographic area, searching also for possible differences at sub-region level. Providing this information could indeed allow eventual management plans to be adapted to the exact growth pattern that the species exhibit in the region, in this way increasing their effectiveness

Geomagnetic survey of Italy. Repeat station network and magnetic maps: a short report

Starting in 1977, two geomagnetic project were undertaken in the frame of the >of the Consiglio Nazionale delle Ricerche(Project>of the National Research Council);1)a new national network of repeat stations for total field F, horizontal component H, vertical component Z, declination D.2)a 2nd order network of stations for F,Z,H to produce geomagnetic maps of Italy. The two projects were carried out by a > made up of Operating Units from Institutions to which the authors belong. The field work ended in 1981. The Istituto Nazionale di Geofisica coordinated the operations for both projects. This paper is intended to give a short report to the international scientific community on this work which has so far only appeared in the Italian literature.Published365-3681A. Geomagnetismo e PaleomagnetismoN/A or not JC

Geomagnetic survey of Italy at 1979.0 Repeat station network and magnetic maps

attached an anomaly map for FA national network of 106 repeat stations for total field F, horizontal component H, vertical component Z and declination D has been undertaken in the frame of the 'Progetto Finalizzato Geodinamica' of the Consiglio Nazionale delle Ricerche. From the observed magnetic elements the repeat station values were referred to 1979.0 and five normal fields in the form of a 2nd order polynomial in latitude and longitude were computed: GDN for the whole Italian area, GDN-N for the northern Italy, GDN_C for central Italy, GDN-S for the southern Italy and GDN-Sn for Sardinia. From comparisons made on F between GDN and two planetary reference fields it has concluded that for total field the polynomial form can be well considered as representative of the main field in the Italian area. A 2nd order network of 2500 stations for F, Z, H, has been undertaken to produce geomagnetic maps of Italy. An anomaly map for F referred to the GDN normal field has been drawn. The main features of anomalies configuration are described.Published1-171A. Geomagnetismo e PaleomagnetismoN/A or not JC

Evolution of fluviokarst canyons in response to the Quaternary tectonic uplift of the Apulia Carbonate Platform (southern Italy): Insights from morphometric analysis of drainage basins

The evolution of fluviokarst landscapes results from the interplay of karst and fluvial processes, all driven by rock uplift or base level fall. The fluviokarst landscape of the Murge Plateau in the central Apulian Region (southeastern Italy) is characterized by narrow, steep-sided, V-shaped canyons, locally called ‘Gravine’, and deeply incised into the Plio-Pleistocene deposits of the Bradanic Trough and the underlying Apulian limestone bedrock. Previous studies propose alternative models of canyons development, however identifying a dominant morphogenetic process for the evolution of the ‘Gravine’ fluviokarst drainage basins remains an open question. The results of our regional morphometric analysis reveal a marked transition from the relict, low-relief landscape preserved in the Murge uplands to the steep channel reaches below prominent knickpoints showing evidence of a transient wave of river incision that is propagating inland. We observe anomalies of mean local relief and channel steepness, and the distribution of fluvial knickpoints consistent with a regional uplift affecting the Murge Plateau since Middle-Late Pleistocene. These findings demonstrate that the history of landscape evolution was dominated by fluvial processes. Using transformed river profile analysis we show that χ anomalies in the ‘Gravine’ trunk channels indicate drainage basin instability by drainage area capture. The convex-shape of the hypsometric curves and high hypsometric integrals confirm that the disequilibrium state of the 13 analyzed basins results from a combination of regional uplift and subsequent river network reorganization and plateau area captures. Based on our results, we propose a new model of landscape evolution for the ‘Gravine’ fluviokarst drainage basins

EGU General Assembly 2016, held 17-22 April, 2016 in Vienna Austria, id. EPSC2016-16813

A new approach to identify contributing fractures and ambient wellbore flow in fractured and karst aquifers is presented. It is time efficient, low cost and based on a benign tracer: the dissolved oxygen (DO). The method was already applied by other scientists to test fractured crystalline rock wells. The DO method consists in elevating water DO concentration in a borehole by bubbling air at assigned water depths using a porous polypropylene tube (bubbler) connected to a compressed air tank with tubing. After the aeration, the resulting profile should be a linear increase in DO with depth due to the effects of water pressure on oxygen solubility. Any changes in the DO profile will be then observed when water flows into and through the well. DO dilution can be used to locate inflowing fractures and to define active flow zones in wells. Where there is no change in the DO profile “dead zones” in the well, where no flow is taking place, can be identified. The DO tests in this work have been carried out in the industrial area of Bari, at the experimental station of five wells drilled at the CNR-IRSA. The wells penetrate karstic limestone. Results show enhanced flow through at depths between 32 and 37 meters below the water level and connecting patterns between the studied wells. The benefits of utilizing DO as a tracer include ease of accessibility, low cost and time-efficiency as well as non-toxic nature of the tracer and no impact on flow conditions

Growth and age validation of the thornback ray (Raja clavata Linnaeus, 1758) in the South Adriatic Sea (Central Mediterranean)

Raja clavata is the most widespread and landed skate species in the Mediterranean Basin. Despite its diffusion and economic importance, several aspects of its life history, such as age and growth, are poorly understood. This study evaluated the species’ growth in the South Adriatic Sea (Central Mediterranean Sea) and for the first time attempted an age validation through a tagging experiment. Thin sectioning of vertebral centra proved to be a more accurate preparation method in terms of age estimation precision and reproducibility than whole vertebral centrum staining (cobalt nitrate and ammonium sulfide technique). Marginal analysis showed a clear seasonal pattern, confirming the hypothesis of a single annulus deposition per year. A total of 291 vertebral centra were sampled and used for age estimation purposes. The oldest female was estimated to be 12 years old [total length (TL) = 89 cm], while the oldest male was aged 8 years (TL = 79.9 cm). Females were also found to be characterized by a slightly wider longevity range (ωL = 11.5, ωU = 16.8 years) than males (ωL = 7.8, ωU = 11.2 years). The von Bertalanffy growth curve fit the age and length data more accurately than the Gompertz and logistic models. Eighty-three thornback rays were tagged and released, of which two were recaptured. In both recaptured specimens, oxytetracycline marks were clearly visible. The band deposition after oxytetracycline injection and growth during the freedom period (about 1 year) were consistent with the age estimation method and criteria used and with the obtained growth results. Thus, the analysis of the vertebral centra extracted from the two recaptured specimens confirmed the hypothesis of the deposition of a single annulus per year and in general the age estimation criteria used in this study