Range expansion and redefinition of a crop-raiding rodent associated with global warming and temperature increase

Since the 1970s, the crested porcupine Hystrix cristata has shown a marked range expansion in Italy. A web page has been created to collect occurrences of this species to monitor its distribution redefinition. Thus, aims of this work were (i) to identify the main predictors promoting the distribution of this large rodent in Italy and (ii) to predict its potential expansion under future climate change scenarios. A total of 1674 locations were used for this analysis, i.e., all those collected through the web page, with the exception of recently introduced populations (Sardinia, Western Liguria and Province of Varese). The current distribution of the crested porcupine covers a total of 135,177 km², as estimated through ensemble predictions. Future climate change scenarios for 2050 and 2070 show that a further range expansion by this species would occur up to 225,576 km², mainly towards areas where the species was historically absent. The increase of isothermality (i.e., the ratio between the mean diurnal and the annual temperature range) and the mean temperature of the driest months would help crested porcupines to reach high altitudes, e.g., in the Alps. In mountain habitats, the ongoing global warming is shifting the distribution of European forests to high elevations, thus potentially providing porcupines with suitable habitats. A reduction in snow cover and the snow period at ground level would remove an important barrier to the range expansion of the crested porcupine in Italy, and thus facilitate digging and food search by this large rodent. Despite being protected at national and international levels, the crested porcupine is reported to be an introduced species to Italy and, therefore, monitoring its range expansion is required. Furthermore, there are complaints about crop damage in agriculture ecosystems, and the species is still widely poached, thus additional management practices are required. Thus, given the conservation interest of this large rodent, an integrated and constantly updated monitoring system that sustains an addressed set of decision-making tools is recommended.     

Relations between climatic–geomorphological parameters and sediment yield in a mediterranean semi-arid area (Sicily,southern Italy)

In the present work on-going research is discussed whose primary goal is to test some statistical methods to estimate the average yearly area-specific sediment yield (SSY). Using geomorphological and climatic parameters various multiple regression formulae have been set up based on SSY observed data from 16 catchments of Sicily. Three distinct techniques were adopted to select the parameters to be used in the equations: simple correlation, stepwise regression analysis and a supervised geomorphological–statistical correlation. The comparison of the results showed the effectiveness of the stepwise analysis, which led to a regression equation with a coefficient of determination (r ²) of 0.87. Nevertheless, even this methodology showed some elements of uncertainty that have caused, in some cases, appreciable differences between observed and predicted values (mean percentage error equal to 26%). These differences are likely either due to the hydraulic regime of most of Sicilian watercourses (typical of semi-arid regions) or to hidden factors (e.g., topography, human impact and concentrated erosion), which can greatly affect the processes of sediment production and transport. The study has pointed out the need to take into account a larger number of observations and to perform the analysis of relations between suitable variables and SSY at a more detailed time resolution.     

The chemical and hydrologic structure of Poa´s Volcano, Costa Rica

Comparison of the chemical characteristics of spring and river water draining the flanks of Poa´s Volcano, Costa Rica indicates that acid chloride sulfate springs of the northwestern flank of the volcano are derived by leakage and mixing of acid brines formed in the summit hydrothermal system with dilute flank groundwater. Acid chloride sulfate waters of the Rio Agrio drainage basin on the northwestern flank are the only waters on Poa´s that are affected by leakage of acid brines from the summit hydrothermal system. Acid sulfate waters found on the northwestern flank are produced by the interaction of surface and shallow groundwater with dry and wet acid deposition of SO₂ and H₂SO₄ aerosols, respectively. The acid deposition is caused by a plume of acid gases that is released by a shallow magma body located beneath the active crater of Poa´s.No evidence for a deep reservoir of neutral pH sodium chloride brine is found at Poa´s. The lack of discharge of sodium chloride waters at Poa´s is attributed to two factors: (1) the presence of a relatively volatile-rich magma body degassing at shallow depths (< 1 km) into a high level summit groundwater system; and (2) the hydrologic structure of the volcano in which high rates of recharge combine with rapid lateral flow of shallow groundwater to prevent deep-seated sodium chloride fluids from ascending to the surface. The shallow depth of the volatile-rich magma results in the degassing of large quantities of SO₂ and HCl. These gases are readily hydrolyzed and quickly mix with meteoric water to form a reservoir of acid chloride-sulfate brine in the summit hydrothermal system. High recharge rates and steep hydraulic gradients associated with elevated topographic features of the summit region promote lateral flow of acid brines generated in the summit hydrothermal system. However, the same high recharge rates and steep hydraulic gradients prevent lateral flow of deep-seated fluids, thereby masking the presence of any sodium chloride brines that may exist in deeper parts of the volcanic edifice.Structural, stratigraphic, and topographic features of Poa´s Volcano are critical in restricting flow of acid brines to the northwestern flank of the volcano. A permeable lava-lahar sequence that outcrops in the Rio Agrio drainage basin forms a hydraulic conduit between the crater lake and acid chloride sulfate springs. Spring water residence times are estimated from tritium data and indicate that flow of acid brines from the active crater to the Rio Agrio source springs is relatively rapid (3 to 17 years). Hydraulic conductivity values of the lava-lahar sequence calculated from residence time estimates range from 10⁻⁵ to 10⁻⁷ m/s. These values are consistent with hydraulic conductivity values determined by aquifer tests of fractured and porous lava/pyroclastic sequences at the base of the northwestern flank of the volcano.Fluxes of dissolved rock-forming elements in Rio Agrio indicate that approximately 4300 and 1650 m³ of rock are removed annually from the northwest flank aquifer and the active crater hydrothermal system, respectively. Over the lifetime of the hydrothermal system (100's to 1000's of years), significant increases in aquifer porosity and permeability should occur, in marked contrast to the reduction in permeability that often accompanies hydrothermal alteration in less acidic systems. Average fluxes of fluoride, chloride and sulfur calculated from discharge and compositional data collected in the Rio Agrio drainage basin over the period 1988–1990 are approximately 2, 38 and 30 metric tons/day. These fluxes should be representative of minimum volatile release rates at Poa´s in the last 10 to 20 years.     

The Valanginian carbon isotope event: a first episode of greenhouse climate conditions during the Cretaceous

Lower Cretaceous pelagic carbonates outcropping along the Southern Alps of northern Italy provide a record of Tethyan palaeoceanography as well as of low frequency fluctuations in the global carbon cycle. The carbonate C-isotope stratigraphy established at five selected localities in the Southern Alps allows an accurate picture to be drawn of the duration and amplitude of the Valanginian C-isotope event. δ¹³C values near 1.25–1.50% determined in Berriasian and lower Valanginian sediments are replaced by more pdsitive δ¹³C values near 3% in the late Valanginian. The carbonate C-isotope excursion ends in the early Hauterivian with values fluctuating between 1.5% and 2%. The carbonate C-isotope excursion is accompanied by a positive excursion in the total organic carbon C-isotope curve. The Valanginian C-isotope excursion identified in Tethyan sediments correlates with a C-isotope excursion recorded in the western North Atlantic, in the Gulf of Mexico, and in the Central Pacific (DSDP Sites 534,391,535 and 167). By analogy with the Aptian stage, also marked by a significant positive C-isotope excursion, the time of positive δ¹³C values is regarded as a time of accelerated carbon cycling coupled with increased burial rates of organic carbon and detrital material in oceanic sediments. A warm and humid climate, possiblycoupled with a high atmospheric CO₂ content and a high global sea-level, may have triggered the acceleration of the global carbon cycling. In this case the Valanginian C-isotope event would reflect a first episode of Greenhouse Earth conditions during the Cretaceous.     

Analysis of a lower jurassic geomagnetic reversal based on a model that relates transitional fields to variations of flux on the core surface

Summary For the last 12 Myr the transitional virtual geomagnetic poles (VGPs) of different reversals lie close to two preferred and practically antipodal longitudinal paths. In spite of some controversies about these transitional paths, it has been pointed out that they are linked to geomagnetic phenomena. Jurassic transitional VGP paths are quite similar to those of the last 12 Myr. Paleomagnetic data recorded in Stormberg Lavas (195 ± 5 Ma) belonging to two sampling localities of South Africa have been rotated according to an absolute palaeoreconstruction of Africa for the lower Jurassic. In order to avoid the hypothesis about dipolarity implicit in the VGPs calculations, the transitional directions recorded in the lavas were compared with others that were simulated on the basis of a model that relates transitional fields to variations of flux on the Earth's core surface. They were quite similar. For both, recorded and simulated data, the VGPs showed similar paths. Similar conditions could thus have driven both late Cenozoic and Jurassic reversals.     

Vertical migration of Coregonid larvae in the first two months of development

Using an acoustic system in a 9 m deep enclosure, the daily vertical distribution patterns of whitefish larvae were studied from hatching to the age of two months. Four patterns of daily vertical distribution and migration were observed in accordance to different developmental stages:

1. Newly hatched larvae dispersed in the enclosure during the day and congregated at the water surface at night.
2. After 2 weeks of age larvae stayed close to the water surface during day and night.
3. At 15 to 18 mm length, larvae showed distinct vertical migration at dawn and dusk, they stayed close to the surface during the day and dispersed at night.
4. At 28 mm length the depth pattern was reversed. These fish frequented greater depths during the day than at night.

No relation was found between larval depth distribution or vertical migration and food availability or water temperature. Low levels of solar radiation triggered the dawn and dusk vertical migration behaviour of the more developed larvae. Possible reasons for the different behaviour patterns occurring over time are discussed.     

Modelling seasonal variations of natural radioactivity in soils: A case study in southern Italy

The activity of natural radionuclides in soil has become an environmental concern for local public and national authorities because of the harmful effects of radiation exposure on human health. In this context, modelling and mapping the activity of natural radionuclides in soil is an important research topic. The study was aimed to model, in a spatial sense, the soil radioactivity in an urban and peri-urban soils area in southern Italy to analyse the seasonal influence on soil radioactivity. Measures of gamma radiation naturally emitted through the decay of radioactive isotopes (potassium, uranium and thorium) were analysed using a geostatistical approach to map the spatial distribution of soil radioactivity. The activity of three radionuclides was measured at 181 locations using a high-resolution ?-ray spectrometry. To take into account the influence of season, the measurements were carried out in summer and in winter. Activity data were analysed by using a geostatistical approach and zones of relatively high or low radioactivity were delineated. Among the main processes which influence natural radioactivity such as geology, geochemical, pedological, and ecological processes, results of this study showed a prominent control of radio-emission measurements by seasonal changes. Low natural radioactivity levels were measured in December associated with winter weather and moist soil conditions (due to high rainfall and low temperature), and higher activity values in July, when the soil was dry and no precipitations occurred.