The International Centre for Advanced Studies on River-Sea Systems "DANUBIUS-RI" is a pan-European Research Infrastructure (RI) developed to support the Research and Innovation (R&I) needs to achieve healthy River-Sea Systems (RSSs). DANUBIUS-RI's Mission is: to facilitate and contribute to excellent science on the continuum river-sea; to offer state-of-the-art research infrastructure to develop a multidisciplinary and transdisciplinary dialogue between river and marine research communities; and to provide the integrated knowledge required to sustainably manage and protect RSs. The DANUBIUS-RI Strategic Research and Innovation Agenda surveyed the major needs from the research community, defining the RI Research Goals. DANUBIUS-RI superintends ten Supersites corresponding to the major European RSs. Each Supersite provides an integrated infrastructure made of optimized observational systems, modelling and forecasting systems, toolboxes, living labs, and services to investigate issues connected to the interaction processes between continental and marine systems. This paper describes the Italian Supersite "Po Delta and North Adriatic Lagoons (Venice and Marano-Grado)", which focuses on coastal transitional environments within the RSs. We present the structure of the Supersite, the interconnections with the international Nodes, in particular the modeling and observational capability and the data management, and the strategy for teaming up an interconnected community of researchers and stakeholders. The infrastructure aims to enhance the observational (in-situ and remote) and modelling capability in the area for improving the quantification of water, sediment and nutrient loads from the rivers and their influence on the coastal zone. Data and information will form the basis of a digital representation of the Po Delta and North Adriatic Lagoons to support a set of services for managing the RSSs and advancing the blue growth in coastal zones.

Understanding the dynamics of coastal marine ecosystems is fundamental for assessing environmental health and addressing anthropogenic impacts. This study analyzes a decade-long dataset of high-resolution Chlorophyll fluorescence (ChlF) measurements collected hourly from August 2012 to December 2022 at the E1 meteo-oceanographic buoy (Böhm et al. 2016). The buoy is located in the Northern Adriatic Sea (44° 08.58’ N; 12° 34.20’ E), approximately 100 km south of the Po River delta and 7 km northeast of Rimini, Italy. As part of the “Delta del Po and Costa Romagnola” (Bergami and Riminucci 2025) research site within the Italian LTER network and the PNRR ITINERIS project, the E1 station provides a unique platform for multidisciplinary research and long-term environmental monitoring. ChlF data, collected by the WET Labs ® ECO Triplet (now SeaBird Scientific), reveal significant seasonal and interannual variations in chlorophyll concentration, estimates from in situ ChlF, ranging from below detection limits to a maximum daily average of 41 μg/L. Together with ChlF, other meteorological, chemical, and physical parameters such as temperature (TEMP), dissolved oxygen (DO), salinity (SAL), turbidity (TURB), and wind speed (WS) were incorporated for this study (Riminucci et al. 2024, Riminucci et al. 2025). A total of 40 distinct algal bloom events were identified using ChlF concentration thresholds and growth rate dynamics (Trombetta et al. 2019). The analysis of bloom frequency revealed two main periods of bloom events per year (Fig. 1), with the identified blooms lasting an average of 13±10 days. During these events, ChlF concentration increased to an average of 6.5 μg/L, indicating substantial algal growth, compared to a baseline of 2.8 μg/L observed outside bloom periods. The most intense blooms occurred in spring, driven by nutrient inputs and increased sunlight, while summer blooms were weaker, less frequent, and shorter in duration due to thermal stratification. In contrast, autumn and winter saw a resurgence of bloom activity, influenced by freshwater inflow, nutrient resuspension, and strong mixing. These seasonal patterns underscore the dynamic interplay between temperature, wind, and nutrient availability in shaping phytoplankton dynamics. Principal Component Analysis (PCA) was conducted to identify key relationships among environmental variables and their influence on algal blooms (Fig. 2). The strong correlation between ChlF and DO during bloom periods reflects the role of photosynthesis in elevating oxygen levels. TEMP and SAL are linked due to seasonal stratification, while WS and TURB highlight wind-driven physical disturbances, such as sediment resuspension and waves. Overall, PCA captures both seasonal and biological processes, including bloom dynamics, as well as physical disturbances driven by wind and water movement. Seasonal factors govern bloom dynamics, with spring and late autumn/winter supporting phytoplankton growth due to favourable nutrient availability and stable conditions, while summer stratification limits blooms. These findings underscore the interplay of biological and physical drivers in shaping the ecosystem response over the decade. Two bloom types were identified: Single-Peak Blooms, typical in spring, characterized by rapid growth and short durations, and Multi-Peak Blooms, more common in autumn, with extended periods due to intermittent nutrient apportion. Nutrient-rich freshwater inputs from the Po River, nitrogen and phosphorus, and seasonal cycles of phytoplankton play a significant role in driving these blooms. Diatoms such as Skeletonema marinoi dominate the winter bloom, while spring and autumn blooms are diatom-driven, modulated by rainfall and nutrient runoff (Grilli et al. 2020, Totti et al. 2019). Summer, characterized by water column stratification, generally exhibits lower ChlF concentrations unless disturbed by storms or mixing events that reintroduce nutrients into surface waters. These findings emphasize the complex seasonal and environmental drivers shaping bloom dynamics. This study introduces a methodological framework for detecting coastal algal blooms by analyzing patterns derived from in-situ fluorescence measurements, offering insights into bloom dynamics. While challenges such as data gaps due to sensor maintenance and biofouling, the findings underscore the value of long-term, high-frequency observations in understanding environmental processes and managing coastal ecosystems. Future research should focus on integrating complementary datasets, such as nutrient concentrations or satellite observations, to deepen the understanding of bloom drivers. Additionally, expanding datasets temporally, by including more years, and spatially, by incorporating other monitoring systems (e.g., fixed-point stations), will further enhance the robustness and applicability of the framework.

This paper presents the development of OpenCHIRP, an innovative sub-bottom profiler (SBP) designed for high-resolution seismic reflection surveys in shallow-water marine and lacustrine environments. The instrument employs chirped (frequency-modulated) impulses to penetrate the first few meters of unconsolidated sediments below the seafloor. Key characteristics include low cost, light weight, and low energy consumption, making it particularly suitable for deployment onboard Autonomous Surface Vehicles (ASVs). We discuss design, functionality, and potential applications of this innovative instrument, as well as results of the preliminary tests.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23060119

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23060119

Newly collected morphobathymetric and seismic reflection data from the Valli di Comacchio coastal lagoons, south of the Po River delta (Northeast Italy), combined with historical, remote sensing, and geodetic data highlight a complex geological evolution during the Holocene, strongly affected by anthropic control. All data allowed us to define the present-day depositional environment of the lagoons and reconstruct their recent (late Pleistocene/Holocene) geo-history. We focused on the effects of the anthropic impacts in modifying the pristine environments created by the Holocene transgression along the Adriatic Sea coast, at the mouth of a major river. They include land reclamation works, artificial damming, channel excavations, fluvial diversions, and a recent (last decades) increase in subsidence rate due to gas and water withdrawals. Despite the development of economic activities, which promoted occupation and exploitation of this area in the last millennia, the post-Glacial evolution of the lagoons shows the important role of inherited morphological features, such as sand ridges and barriers. This complex and relatively well-documented evolution makes the Comacchio lagoons a unique example of deep connections between natural processes and long-term human controls, offering insights into the management policies of these important and delicate environments challenged by global changes.

Sandy beaches and the nearshore environment are dynamic coastal systems characterized by sediment mobilization driven by alternating stormy and mild wave conditions. However, this natural behavior of beaches can be altered by coastal defense structures. Repeated surveys carried out with autonomous surface vehicles (ASVs) may represent an interesting tool for studying nearshore dynamics and testing the effects of mitigation strategies against erosion. We present a one-year experiment involving repeated stratigraphic and morpho-bathymetric surveys of a nearshore environment prone to coastal erosion along the Emilia-Romagna coast (NE Italy), the Lido di Dante beach, carried out between October 2020 and December 2021 using an ASV. Seafloor and subseafloor “snapshots” collected at different time intervals enabled us to delineate the seasonal variability and shed light on key controlling variables, which could be used to integrate and calibrate remote-sensing observations and modeling. The results demonstrated that repeated surveys could be successfully employed for monitoring coastal areas and represent a promising tool for studying coastal dynamics on a medium/short (years/months) timescale.

The fast ongoing progress in the field of the “open content” technologies, i.e., those hardware and software resources designed and offered to a wide community by people belonging to the open-source culture movement, strengthened and fostered by the availability of low cost, highly performing electronic devices, is creating a “revolution” in the world of applied sciences. This is particularly true for waterborne geological-geophysical data acquisition in shallow water environments, such as marine coasts, lagoons, lakes and rivers, sites that preserve, in general, relatively continuous recent geological records. We presented some examples of geophysical data acquisition in different shallow water environments carried out by means of an unmanned surface vehicle (USV) equipped with different sensors providing high-resolution images of the sediment–water interface and some tens of meters within the sediments. The tests indicate that these technologies can be employed to collect densely spaced grids of high-resolution data, quickly, efficiently and at a very low cost, allowing for execution of repeated surveys even in those areas not accessible through conventional systems. The intensive use of “open” technologies and software for data acquisition and processing has the potential of widening the application of these methods to an increasing audience of earth scientists studying geological processes in rapidly evolving environments.

The present dataset was collected to evaluate the environmental stressors on a lacustrine basin in the Eastern Alps of glacial origin that has been affected in recent years by natural and anthropogenic events such as the construction of a hydroelectric power plant and a series of strong earthquakes during 1976-1977. We collected sediment cores in different sites from the lake margins to the depocenter and performed a multiproxy analysis of sediment sample to highlight lake stratigraphy and major changes occurring at a decadal scale (Polonia et al., [1]). The integrated analyses of sedimentological, geochemical, isotopic, mineralogical and micropaleontological analyses aimed at reconstructing changes in sediment composition and define the triggering mechanisms of altered environmental conditions. The dataset demonstrates that evaluating ex post the effects of artificial modification in a natural environment during relatively long time spans (decades) can provide important insights for managing and protection strategies in similar environments worldwide

The Lake of Cavazzo is a natural, lacustrine basin in the Friuli-Venezia Giulia region (NE Italy), which occupies a fluvio-glacial suspended valley of the Tagliamento river, at the southern front of the Alpine chain. The lake formed after the melting of major glacial tongues at the end of the Last Glacial Maximum, and has been affected in recent years by natural and anthropogenic events, with economic, cultural and environmental consequences. According to local witnesses, the lake environment has changed dramatically after the 1950s, when the basin was connected to a hydroelectric power plant collecting waters from a wider catchment area, as it served as its final discharge basin. In this work, based on a densely-spaced grid of high-resolution seismic reflection profiles complemented by sediment cores, we analysed the uppermost lake stratigraphy, highlighting major changes occurring at a decadal scale. Our main purpose is to verify whether and how the lake sediments record the transition from pristine/natural to artificial conditions, as well as the effects of multiple natural impacts including the 1976-77 Friuli earthquake sequence. The results of our analysis suggest varying environmental conditions of the lake after the 1950s indicated by changing sediment mineralogy, increased deposition of allochthonous clastic sediments, and recurrent episodes of anoxic conditions at the lake's floor, likely triggered by hyperpycnal flows derived from the hydroelectric power plant discharges. We also observe that the effects of the 1976-77 seismic sequence are recorded in the lake as resedimented levels, likely due to shaking, in situ deformation, landslides, and turbidity currents. Our results stress the importance of lacustrine environments as efficient recorders of anthropogenic and natural events. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

The increasing quality and resolution of marine seismic reflection data, as well as their availability in digital form within large data sets, require the development and testing of new techniques to improve their interpretation. In this work, we present a case study dealing with application of 3D techniques to a set of 2D shallow-water data, where the effect of lateral reflections/diffractions can be neglected. We show how such techniques can be effective in highlighting geological properties/features of the seafloor and sub-seafloor, including reflectivity analysis of prominent horizons, seismic facies classification based on definition of acoustic properties, and compilation of a "flattened" version of seismic sections, by time shifting a particular reflector to a horizontal reference level. This latter technique enables compilations of pseudo-3D grids of seismic volumes, that could be subsequently sampled (time sliced) allowing for compilation of seismic amplitude and reflectivity maps which could be used to infer geological properties and processes.

OpenSWAP is a class of innovative open architecture, low cost autonomous vehicles for geological/geophysical studies of shallow water environments. Although they can host different types of sensors, these vehicles were specifically designed for geophysical surveys, i.e., for the acquisition of bathymetric and stratigraphic data through single- and multibeam echosounders, side-scan sonars, and seismic-reflection systems. The main characteristic of the OpenSWAP vehicles is their ability of following pre-defined routes with high accuracy under acceptable weather and sea conditions. This would open the door to 4D (repeated) surveys, which constitute a powerful tool to analyze morphological and stratigraphic changes of the sediment/water interface and of the shallow substratum eventually caused by sediment dynamics (erosion vs. deposition), slumps and gravitative failures, earthquakes (slip along seismogenic faults and secondary effects of shaking), tsunamis, etc. The low cost and the open hardware/software architectures of these systems, which can be modified by the end users, lead for planning and execution of cooperative and adaptive surveys with different instruments not yet implemented or tested. Together with a technical description of the vehicles, we provide different case studies where they were successfully employed, carried out in environments not, or very difficultly accessed through conventional systems.

The 1908 Tunguska Event is one of the best studied cases of a cosmic body impacting the Earth with global effects. However, still today, significant doubts are casted on the different proposed event reconstructions. In the present work, we would like to revisit the atmospheric fragmentation of the Tunguska Cosmic Body (TCB) by taking into account the possibility that a metre-sized fragment caused the formation of the Lake Cheko, located at about 9km NW the epicentre. Our work favours the hypothesis that the TCB was a rubble-pile asteroid composed by boulders with very different materials with different mechanical strengths, density, and porosity. The TCB was divided at least into two pieces by a close encounter with the Earth, short before the impact with our Planet: the main body (60m) produced the well-known airburst that devastated more than 2000km^2 of Siberian taig`a, while the secondary one (6-10m) fell without fragmentation in the Kimchu river region and excavated a 50m depression, which presently hosts the Lake Cheko. This hypothesis requires that the secondary body was an extremely compact stone with high mechanical strength (300MPa). It is a high, but not unrealistic, value, as shown by a similar case that occurred in 2007 near the village of Carancas (Peru). An extreme compactness is not necessary, if one considers that the crater excavation could be enhanced by the explosion of permafrost-trapped methane released and ignited during the impact process. In this case, a smaller fragment (2m) with an average mechanical strength could reach the ground without fragmentation and is sufficient to excavate the Lake Cheko. We exclude the hypothesis of a single cosmic body ejecting a metre-sized fragment during or shortly before the airburst, because the resulting lateral velocity of such a large boulder was not enough to deviate to reach the alleged impact site.

The 1908 June 30 Tunguska Event (TE) is one of the best studied cases of cosmic body impacting the Earth with global effects. However, still today, significant doubts are casted on the different proposed event reconstructions, because of shortage of reliable information and uncertainties of available data. In the present work, we would like to revisit the atmospheric fragmentation of the Tunguska Cosmic Body (TCB) by taking into account the possibility that a metre-sized fragment could cause the formation of the Lake Cheko, located at about $9$~km North-West from the epicentre. We performed order-of-magnitude calculations by using the classical single-body theory for the atmospheric dynamics of comets/asteroids, with the addition of the fragmentation conditions by Foschini (2001). We calibrated the numerical model by using the data of the Chelyabinsk Event (CE) of 2013 February 15. Our work favours the hypothesis that the TCB could have been a rubble-pile asteroid composed by boulders with very different materials with different mechanical strengths, density, and porosity. Before the impact, a close encounter with the Earth stripped at least one boulder, which fell aside the main body and excavated the Lake Cheko. We exclude the hypothesis of a single compact asteroid ejecting a metre-sized fragment during, or shortly before, the airburst, because there is no suitable combination of boulder mass and lateral velocity.

Data collected during active and passive seismic surveys can be stored in many different, more or less standard, formats. One of the most popular is the SEG-Y format, developed since 1975 to store single-line seismic digital data on tapes, and now evolved to store them into hard-disk and other media as well. Unfortunately, sometimes, files that are claimed to be recorded in the SEG-Y format cannot be processed using available free or industrial packages. Aiming to solve this impasse we present segy-change, a pre-processing software program to view, analyze, change and fix errors present in SEG-Y data files. It is written in C language and it can be used also as a software library and is compatible with most operating systems. Segy-change allows the user to display and optionally change the values inside all parts of a SEG-Y file: the file header, the trace headers and the data blocks. In addition, it allows to do a quality check on the data by plotting the traces. We provide instructions and examples on how to use the software.

ACqUISITION OF GEOPHYSICAL DATA IN SHALLOW-WATER ENVIRONMENTS USING AUTONOMOUS VEHICLES: STATE OF THE ART, PERSPECTIVES AND CASE HISTORIES L. Gasperini1, F. Del Bianco2, G. Stanghellini1, F. Priore3 1 ISMAR, Istituto di Scienze Marine, U.O. Geologia Marina, CNR, Bologna, Italy 2 Consorzio Proambiente, Bologna, Italy 3 Dip. di Fisica e Scienze della Terra “Macedonio Melloni”, Università degli Studi di Parma, Italy

The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. We analysed the structural style of the frontal accretionary wedge through a multi-scale geophysical approach. Pre-stack depth-migrated crustal-scale seismic profiles unravelled the overall geometry of the subduction complex; high-resolution multi-channel seismic and sub-bottom CHIRP profiles, together with morpho-structural maps, integrated deep data and constrained the fine structure of the frontal accretionary wedge, as well as deformation processes along the outer deformation front.We identified four main morpho-structural domains in the western lobe of the frontal wedge: the proto-deformation area at the transition with the abyssal plain; two regions of gentle and tight folding; a hummocky morphology domain with deep depressions and intervening structural highs; a highstanding plateau at the landward limit of the salt-bearing accretionary wedge, where the detachment cuts through deeper levels down to the basement. Variation of structural style and seafloor morphology in these domains are related to a progressively more intense deformation towards the inner wedge, while abrupt changes are linked to inherited structures in the lower African plate. Our data suggest focusing of intense shallow deformation in correspondence of deeply rooted faults and basement highs of the incoming plate.Back-arc extension in the Southern Tyrrhenian Sea has recently ceased, producing a slowdown of slab rollback and plate-boundary re-organization along trans-tensional lithospheric faults segmenting the continental margin. In this complex setting, it is not clear if the accretionary wedge is still growing through frontal accretion. Our data suggest that shortening is still active at the toe of the wedge, and uplift rates along single folds are in the range of 0.25-1.5 mm/yr. An unconformity within the Plio-Quaternary sediments suggests a discontinuity in sedimentation and tectonic processes, i.e. a slowdown of shortening rate or an increase in sedimentation rate, but not a real inactivation of frontal accretion, which still contributes to the migration of the outer deformation front towards the foreland.