Spatial distribution of introduced brook trout Salvelinus fontinalis (Salmonidae) within alpine lakes: evidences from a fish eradication campaign

Brook trout Salvelinus fontinalis have been used worldwide to stock fishless alpine lakes, negatively affecting native biota. Understanding its spatial ecology in invaded ecosystems can provide information to interpret and contrast its ecological impact. We opportunistically used capture points of brook trout gillnetted during an eradication campaign to assess the distribution patterns of four unexploited populations inhabiting high-altitude lakes. The main eradication method implies the use of many gillnets with several mesh sizes, which are selective for different fish sizes. For each lake we drew six capture maps associated with as many different mesh sizes, and we tested whether the distance from the coastline (which in alpine lakes is a reliable proxy of the most important spatial gradients, e.g. depth, temperature, prey availability, lighting conditions) influences the proportion of captured fish belonging to different size classes and the number of fish captured by the nets with different mesh sizes. To interpret the results, we also provide a cartographic description of the lakes’ bathymetry and littoral microhabitats. We found (1) a negative relationship between brook trout distribution and the distance from the coastline in all of the size classes, lakes and mesh sizes; (2) that large brook trout can thrive in the lakes’ center, while small ones are limited to the littoral areas; and (3) that the distance from the coastline alone cannot explain all the differences in the catch densities in different parts of the lakes. As in their native range, introduced brook trout populations also have littoral habits. Microhabitats, prey availability and distance from the spawning ground are other likely factors determining the distribution patterns of brook trout populations introduced in alpine lakes. The obtained results also provide useful information on how to plan new eradication campaigns

Arc development in the Apennines

In central Italy, geometry, kinematics, and tectonic evolution of the late Neogene Umbrian Arc, which is one of the main thrusts of the northern Apennines, have long been studied. Documented evidence for orogenic curvature includes vertical-axis rotations along both limbs of the arc and a positive orocline test along the entire arc. The curvature’s cause is, however, still unexplained. In this work, we focused our attention on the southern portion of the Umbrian Arc, the so-called Olevano-Antrodoco thrust. We analyze, in particular, gravity and seismic reflection data and consider available paleomagnetic, stratigraphic, structural, and topographic evidence from the central Apennines to infer spatial extent, attitude, and surface effects of a mid-crustal anticlinorium imaged in the CROP-11 deep seismic profile. The anticlinorium has horizontal dimensions of about 50 by 30 km and is located right beneath the Olevano-Antrodoco thrust. Stratigraphic, structural, and topographic evidence suggests that the anticlinorium produced a surface uplift during its growth in early Pliocene times. We propose an evolutionary model in which, during late Neogene time, the Olevano-Antrodoco thrust developed in an out-of-sequence fashion and underwent about 16° of clockwise rotation when the thrust ran into and was then raised and folded by the growing anticlinorium (late Messinian-early Pliocene time). This new model suggests a causal link between mid-crustal folding and surficial orogenic curvature that is consistent with several available data sets from the northern-central Apennines; more evidence is, however, needed to fully test hypothesis. Additionally, due to the occurrence of mid-crustal basement-involved thrusts in other orogens, this model may be a viable mechanism for arc formation elsewhere

Gravity modelling along CROP04 seismic profile

The processing and interpretation of seismic lines, together with the analysis of surficial geological data and hydrocarbon wells data, are powerful tools for the investigation of crust structures. Nevertheless, for depths exceeding that portion of crust usually investigated for commercial purposes, only geophysical data are generally available (among the others: NVR seismic from CROP project, DSS data, magnetic data, gravity data). In this context, the possibility of comparing two independent geophysical data sets, such as data from seismic exploration (CROP Project) and gravimetric analysis (Bouguer anomalies), is of particular interest for investigations into the deeper crust portion. In the present work gravity data modelling was used to study deep crust, constraints being provided by WARR data and by reflection seismic data obtained along the CROP04 profile that crosses the Southern Apennines (Italy) from Agropoli (SW) to Barletta (NE). A preliminary interpretation has been made of the regional gravity anomaly trend in deep crust in Southern Italy; the role of this anomaly trend as an independent constraint for the geological interpretation of the CROP04 seismic line is discussed

Arc development in the Apennines

In central Italy, the geometry, kinematics, and tectonic evolution of the late Neogene Umbrian Arc, which is one of the main thrusts of the northern Apennines, have long been studied. Documented evidence for orogenic curvature includes vertical axis rotations along both limbs of the arc and a positive orocline test along the entire arc. The cause of the curvature is, however, still unexplained. In this work, we focus our attention on the southern portion of the Umbrian Arc, the so-called Olevano- Antrodoco thrust. We analyze, in particular, gravity and seismic-reflection data and consider available paleomagnetic, stratigraphic, structural, and topographic evidence from the central Apennines to infer spatial extent, attitude, and surface effects of a midcrustal anticlinorium imaged in the CROP-11 deep seismic profile. The anticlinorium has horizontal dimensions of ~50 by 30 km, and it is located right beneath the Olevano- Antrodoco thrust. Stratigraphic, structural, and topographic evidence suggests that the anticlinorium produced a surface uplift during its growth in early Pliocene times. We propose an evolutionary model in which, during late Neogene time, the Olevano- Antrodoco thrust developed in an out-of sequence fashion and underwent ~16° of clockwise rotation when the thrust ran into and was then raised and folded by the growing anticlinorium (late Messinian–early Pliocene time). This new model suggests a causal link between midcrustal folding and surficial orogenic curvature that is consistent with several available data sets from the northern and central Apennines; more evidence is, however, needed to fully test our hypothesis. Additionally, due to the occurrence of midcrustal basement-involved thrusts in other orogens, this model may be a viable mechanism for arc formation elsewhere

2D gravity modelling along the CROP11 seismic profile

The purpose of this work is to present a gravity reconstruction of the deepest portion of the CROP 11 seismic line. The 2D gravity modelling is constrained by DSS data and by deep reflection seismic data obtained along the CROP 11 line. The role of the regional gravity anomaly trend of Central Italy as an independent constraint for the geological interpretation of the seismic line is also highlighted. The main gravity low (Fucino Plain) in the area is compensated by the combined effect of a regional deepening of both the Moho and the top of the crystalline basement, while the gravity low, located east towards the Maiella Mt., seems to originate between a 4 and 10 km depth. A lower density can be assigned to the western portion of the mantle with respect to the eastern side. The westernmost part of the upper crust in the model also shows a slightly lower density. The crystalline basement is not likely to be heavily involved in the deformation of the chain; ramp-and-flat deformations are present down to a depth of 20 km, i.e. the “highly reflective body” on the western side of the profile, which does not have a marked gravity imprint and should be due to relatively “light” sedimentary units

Ups and downs in western Crete (Hellenic subduction zone)

Studies of past sea-level markers are commonly used to unveil the tectonic history and seismic behavior of subduction zones. We present new evidence on vertical motions of the Hellenic subduction zone as resulting from a suite of Late Pleistocene - Holocene shorelines in western Crete (Greece). Shoreline ages obtained by AMS radiocarbon dating of seashells, together with the reappraisal of shoreline ages from previous works, testify a long-term uplift rate of 2.5-2.7 mm/y. This average value, however, includes periods in which the vertical motions vary significantly: 2.6-3.2 mm/y subsidence rate from 42 ka to 23 ka, followed by ~7.7 mm/y sustained uplift rate from 23 ka to present. The last ~5 ky shows a relatively slower uplift rate of 3.0-3.3 mm/y, yet slightly higher than the long-term average. A preliminary tectonic model attempts at explaining these up and down motions by across-strike partitioning of fault activity in the subduction zone

Il quadro sismotettonico del grande terremoto del 1905

La storia della Calabria è una storia lunga – molto più lunga di quanto qualunque essere umano possa immaginare, aggiungeremmo noi geologi – di grandi e piccoli terremoti. Catastrofi improvvise e catastrofi parzialmente annunciate, terremoti improvvisi e isolati e sequenze interminabili che sembravano non voler lasciare in piedi nulla di questa regione. Lo spaventoso livello di sismicità della Calabria, di cui qualunque calabrese è testimone almeno indiretto, è oggi quantomeno ben accertato da ricerche sempre più specialistiche e dettagliate. Due degli elementi fondamentali per descrivere la sismicità calabrese consistono nello studio dei terremoti del passato e nello studio della geologia e tettonica di questa regione, riconosciuta da sempre come uno dei luoghi maggiormente attivi di tutto il Mediterraneo. Questi elementi confluiscono in modelli di pericolosità sismica (Gruppo di Lavoro MPS, 2004; fig. 1), che puntualmente fotografano una propensione di questa terra a dare terremoti più forti e più frequenti di quanto non avvenga in qualunque altra zona della penisola. Questa relazione tenta di tratteggiare sinteticamente questa forte propensione alla sismicità, muovendosi tra le caratteristiche geologiche della Calabria e la sua poco invidiabile storia sismica. La relazione si avvale di risultati di ricerche recenti e recentissime, condotte sia presso l’Istituto Nazionale di Geofisica e Vulcanologia (INGV), sia dalla comunità sismologica nazionale che fa riferimento alle università. La relazione privilegia ampiamente il materiale iconografico basato su tali ricerche. Per ulteriori approfondimenti si raccomandano i lettori di consultare il sito Internet dell’INGV (www.ingv.it), che nelle sue pagine interne offre numerosissime informazioni di facile accessibilità e comprensione

Deep view of the Subduction-Transform Edge Propagator (STEP) fault in the Calabrian Subduction Zone

The Calabrian Subduction Zone plays a key role in the evolution of the central Mediterranean in the framework of the convergence between Africa and Europe. Here, the remnants of the World’s oldest oceanic crust form a narrow NW-dipping slab passively subducting beneath the Calabrian Arc. Recently published high-resolution seismic profiles and bathymetric data of the western Ionian Sea highlight the presence of a NNW-SSE faulting system connected with a series of Plio-Pleistocene syn-tectonic basins. These features are correlated with the recent activity of a major NNW-SSE deformation zone confining the active subduction to the SW and interpreted as a Subduction-Transform Edge Propagator (STEP) fault. The goal of this work is to jointly reconstruct the geometry of the STEP fault and the subduction interface in its surroundings.We use multichannel seismic profiles acquired in the southwestern part of the Calabrian accretionary wedge to focus on the STEP fault geometry at depth and to analyse its relationships with shallow deformation features. The quantitative analysis and enhancement of seismic data provided an accurate image of the internal structure of the accretionary wedge at various depths, showing growth strata in the Plio-Pleistocene succession and major discontinuities in the lower crust. Our results depict a main subvertical, slightly east-dipping, lithospheric fault cutting the oceanic crust down to the Moho, and a rich set of associated secondary synthetic and antithetic faults. This picture also provides new insights on the STEP fault propagation mechanism. In addition, the tridimensional correlation of the STEP fault occurrences in various seismic profiles provides a preliminary scheme of its segmentation and highlights the relationships of this master fault with other main structural elements of the Calabrian Arc and Eastern Sicily, including some of the faults deemed to be responsible for major historical earthquakes in the area

Regional gravity anomaly map and crustal model of the Central-Southern Apennines (Italy)

The deep structures of the Central–Southern Apennines are analysed on the basis of the regional component of gravity anomalies, obtained applying a stripping technique. This procedure allows the accurate removal of the gravimetric effect of the three-dimensional shallow (within the first 10 km) geological bodies from the observed Bouguer anomaly. The resulting anomaly map differs quite significantly from the Bouguer anomaly map, providing new constraints on the nature of the deeper part of the crust and on the upper mantle. The stripping reveals that the regional gravity lows are shifted westward in comparison with Bouguer anomaly lows. Moreover, the gravimetric pattern indicates a lack of cylindrism for the deep structures of the Apennine Chain, which in the study area can be roughly divided into three main segments. The observed differences between the gravity anomalies pattern of the Central Apennines and that of the Southern Apennines are marked. The integration of gravimetric results with other geophysical data suggests that: (i) a ramp-dominated style for the buried Apulia (Adria) units and part of the underlying basement is compatible with gravimetric data and (ii) most of the regional gravity anomalies in the Central Apennines seem to originate within the lower crust

Invasions of the non-indigenous red alga Lophocladia lallemandii (Montagne) F. Schmitz off the Island of Ischia (Tyrrhenian Sea, Italy)

This paper describes the distribution and spread of the non-indigenous red alga Lophocladia lallemandii (Montagne) F. Schmitz along the coast of the Island of Ischia (Tyrrhenian Sea, Italy). Lophocladia lallemandii was monitored through surveys from July 2019 to January 2020 at the Capo Sant’Angelo (Ischia), where L. lallemandii was observed, but not reported, in the years preceding the invasion of the upper rocky infralittoral shore reported here. It is noteworthy that a large portion of the study area is included within one of the two “B no-take” zones of the Marine Protected Area of the “Regno di Nettuno” (“Neptune’s Realm”). During the surveys, the alga was first observed in the middle of July 2019 and totally disappeared by the middle of January 2020. Algal cover showed two peaks in August (55%) and November (58.5%). Fertile thalli (tetrasporophytes) of L. lallemandii were observed in all of the analysed samples. Thalli were not always strongly attached to the substrate or other algae and could often be easily detached by strong hydrodynamic conditions. These detached thalli were found laying on the bottom in dense turfs or floating or stranding on the beach. Noteworthy were the macroflora and fauna, the latter essentially composed by mollusks and amphipods, living among the branches of the alga, and various fishes hiding within the thick algal turf. These observations indicate that this alga may be a source of food and refuge for the native animal community of the upper rocky infralittoral zone