Mesoscale variations in the assemblage structure and trophodynamics of mesozooplankton communities of the Adriatic basin (Mediterranean Sea)

Zooplankton are critical to the functioning of ocean food webs because of their utter abundance and vital ecosystem roles. Zooplankton communities are highly diverse and thus perform a variety of ecosystem functions, thus changes in their community or food web structure may provide evidence of ecosystem alteration. Assemblage structure and trophodynamics of mesozooplantkon communities were examined across the Adriatic basin, the northernmost and most productive basin of the Mediterranean Sea. Samples were collected in June–July 2019 along coast-offshore transects covering the whole western Adriatic side, consistently environmental variables were also recorded. Results showed a clear separation between samples from the northern-central Adriatic and the southern ones, with a further segregation, although less clear, of inshore vs. off-shore stations, the latter mostly dominated in the central and southern stations by gelatinous plankton. Such patterns were mainly driven by chlorophyll-a concentration (as a proxy of primary production) for northern-central stations, i.e. closer to the Po river input, and by temperature and salinity, for southern ones, with the DistLM model explaining 46 % of total variance. The analysis of stable isotopes of nitrogen and carbon allowed to identify a complex food web characterized by 3 trophic levels from herbivores to carnivores, passing through the mixed feeding behavior of omnivores, shifting from phytoplankton/detritus ingestion to microzooplankton. Trophic structure also spatially varied according to sub-area, with the northern-central sub-areas differing from each other and from the southern stations. Our results highlighted the importance of environmental variables as drivers of zooplanktonic communities and the complex structure of their food webs. Disentangling and considering such complexity is crucial to generate realistic predictions on the functioning of aquatic ecosystems, especially in high productive and, at the same time, overexploited area such as the Adriatic Sea.

Designation of a lectotype for the Canestrini’s Goby, Gobius canestrinii Ninni, 1883 (Teleostei, Gobiiformes, Gobiidae, Gobionellinae)

A recent study based on molecular biological data revealed that Gobius canestrinii (Ninni, 1883), a gobioid fish endemic to the Adriatic basin, has to be split in three lineages. The original description was based on populations from two distant localities in Italy and in Croatia respectively, the first representing one of these lineages, the second most likely belonging to another lineage. To fix the name of the species, we hereby designated a lectotype for Canestrini’s Goby.

A novel methodological approach for land subsidence prediction through data assimilation techniques

Anthropogenic land subsidence can be evaluated and predicted by numerical models, which are often built over deterministic analyses. However, uncertainties and approximations are present, as in any other modeling activity of real-world phenomena. This study aims at combining data assimilation techniques with a physically-based numerical model of anthropogenic land subsidence in a novel and comprehensive workflow, to overcome the main limitations concerning the way traditional deterministic analyses use the available measurements. The proposed methodology allows to reduce uncertainties affecting the model, identify the most appropriate rock constitutive behavior and characterize the most significant governing geomechanical parameters. The proposed methodological approach has been applied in a synthetic test case representative of the Upper Adriatic basin, Italy. The integration of data assimilation techniques into geomechanical modeling appears to be a useful and effective tool for a more reliable study of anthropogenic land subsidence.

New Geographical Record of Three Cumacean Species Eudorella nana, Leucon affinis, Leucon siphonatus and One Rare Amphipod Presence Confirmation, Stenothoe bosphorana, in Adriatic Sea, Italy

Three cumacean species, Eudorella nana Sars, 1879, Leucon affinis Fage, 1951, Leucon siphonatus Calman, 1905, were recorded for the first time and one rare amphipod presence, Stenothoe bosphorana Sowinsky, 1898, was confirmed in the Adriatic basin.

Seismic evidence of the Messinian events in the Adriatic basin

<p>The Adriatic basin represents one of several restricted basins located in the Mediterranean Area. It consists of the foreland of three different orogenic belts: the Dinarides to the East, active during the Eocene, the Southern Alps to the North, active since the Cretaceous time, and the Apennines to the West, active since the Paleogene. The Apennines had a primary role during the Messinian Salinity Crisis (MSC), conditioning the connection between the Adriatic basin, the Ionian basin, and the proto-Tyrrhenian basin. During the Messinian, the present Adriatic Sea was characterized by shallow water domains, where gypsum evaporites initially deposited and often successively incised or outcropped. </p><p>In the past 50 years, a massive dataset, composed of 2D multichannel seismic data and boreholes, was collected, covering almost the whole Adriatic basin in the Italian offshore. In this work, we interpreted the Plio-Quaternary base (PQb), based on available public datasets and on seismic profiles present in literature, which provided regional information from the northernmost Trieste Gulf (Northern Adriatic Sea) to the Otranto Channel (Southern Adriatic Sea). Here, we propose the PQb time-structural map, obtained by analyzing more than 600 seismic profiles. The PQb represents both the Messinian erosion and/or the top of the Messinian evaporites. It is characterized by a high-amplitude reflector, commonly called “horizon M” in the old literature. Principal findings concerning the Messinian event are summarized as below: </p><p>-The Northern Adriatic (Gulf of Trieste, Gulf of Venice, Po delta, Kvarner Area) reveals widespread channelized systems produced by the initial decrease of the sea level, followed by subaerial erosion, related to further sea level decrease. High-grade erosion involved the nearby Adriatic carbonate platform in the Croatian offshore, where deep valleys, filled with Last Messinian or post- Messinian sediments, cut through the limestones.</p><p>-The Central Adriatic (from the Po delta to the Gargano Promontory) displays a higher evaporites accumulation than the northern sector. Meanwhile, the Mid-Adriatic Ridge was already developing, along with the Apennine Chain, which was in a westernmost position. Erosional features in the deeper area are related to channelized systems, which followed the evaporites deposition. Meanwhile, also the Mid-Adriatic Ridge was affected by erosion.</p><p>-The Southern Adriatic (from the Gargano Promontory to the Otranto Channel) is characterized by the Mesozoic Apulia carbonate platform, covered by a thin Cenozoic sequence affected by subaerial erosion or non-deposition. The platform margin and the slope leading to the deepest South Adriatic basin, where a Messinian gypsum layer, also recorded in the Albanian and Croatian offshore, shows a lower level of upper erosion.</p><p>In general, we notice strongly variable thicknesses of the horizon M, which is related to submarine erosion (channels), subaerial erosion (discontinuous surfaces), non-deposition (possible unconformity), and tilting toward the surrounding chains (deepening horizons). In this work, we evaluate these different components from a regional point of view.  </p>

An integrated atmospheric-hydrological model for high-resolution climate projections in the Adriatic Sea basin

<p>AdriaClim is a project funded by the Italy-Croatia CBC Programme aimed at improving climate change information and providing monitoring and management tools for adaptation strategies in Adriatic coastal areas. Among the innovative tools planned, an integrated online coupled (Hydro-Meteo-Ocean-Wave-Biogeochemistry) model for the Adriatic Sea will be developed, which will run high-resolution simulations for the present/past time and future newly developed scenarios. The concept behind the integrated model is a comprehensive high-resolution representation of the hydrological cycle at the regional (Adriatic basin) level, overcoming classical approaches partitioning the description of the main physical processes into different compartments (i.e., ocean, atmosphere and terrestrial hydrology) interacting poorly each other and possibly missing crucial feedback, especially for long-term (climate) analyses.</p><p>This note presents the coupling approach for the atmospheric-hydrological component, introducing the main features that will be developed and the pilot areas used as test cases. The modelling system will be based on the WRF-Hydro architecture, which provides an extensible, multi-scale and multi-physics modelling capability for land-atmosphere coupling studies. WRF-Hydro modelling system will be applied over the whole Adriatic Basin, encompassing many catchments extending over six countries. A single 6 km-resolution domain will be used concerning atmospheric processes, with a further downscaling until 600 m-resolution for hydrological modelling. The hydrological model will be preliminary calibrated against multiple discharge observations in river sections as close to the rivers' mouths as possible with one full year simulation. Later, climatic simulations will be executed in fully coupled fashion for the historical period 2001-2020 and the future period 2031-2050 using the available EUROCORDEX ensembles as regional climate forcings.</p><p>First results of the ongoing activities will be presented, highlighting both the main outcomes in terms of modelling performance and the potential of further coupling to ocean, waves and biogeochemistry modelling components. The complete modelling system will be used for addressing a wide range of issues, including inundation/storm surge, salt wedge intrusion, sediment transport, transport and diffusion of E. coli, deterioration of transitional and coastal waters.</p>

Adriatic mix layer depth changes in September in the recent years

<p>In the recent years Adriatic Sea witnessed to different microbiological, termohaline with also the sea surface temperature changes interleaved with human impact, climate change and shifts in synoptical patterns. Adriatic Sea is under permanently modulated with Adriatic-Ionian Bimodal Oscillating System and North Atlantic Oscillation. This paper shows changes in termohaline properties in September, the period between Summer and Autumn. During summer months most cyclones that are appearing in the Adriatic basin and their tracks are classified as Genoa cyclones with a smaller number of Adriatic Cyclones. Autumn shows a different picture, with an equal number of Genoa, Adriatic, and non-Genoa and non-Adriatic cyclones. Large-scale air flow superimposed with Adriatic circulation have an impact during the transition from summer to autumn. The mix layer depth and termohaline conditions over Eastern Adriatic in the September in the period 2005 – 2020 are detected form a large database of CTD measurements. The data used in this study were collected during acoustic surveys conducted within framework of projects PELMON (2005-2012) and MEDIAS (2013-2020), carried out by Institute of Oceanography and Fisheries and supported by Croatia's Ministry of Agriculture. The CTD SBE25 probes used in the experiment were regularly calibrated and all measurements was quality controlled. In order to extract characteristic patterns from temperature and salinity vertical profiles and to connect them to wind and sea surface air pressure obtained from ERA5 reanalysis the unsupervised learning approach was utilized and the Neural gas algorithm was applied. The results show that the changes in mix layer depth are connected with interannual changes in cyclone path are connected with wind regime.</p><p>This work has been supported in part by Croatian Science Foundation under the project UIP-2019-04-1737 and project MAUD (grant number HRZZ-IP-2018-01-9849).</p>

15-year-long Adriatic hindcast: Sensitivity to atmospheric forcing

<p>The Adriatic basin is narrow and elongated with numerous islands and <span>surrounded</span> in many parts by steep orography. Therefore ocean models of the Adriatic Sea should benefit from high-resolution atmospheric forcing <span>that</span> could properly account for orographic variations. We compare the results of long-term hindcasts obtained by using three different atmospheric reanalyses with different spatial resolutions. The CROCO ocean model (formerly ROMS_AGRIF) was configured on a relatively coarse 4 km grid, which we consider fine enough to observe the effects of different forcing resolutions, but still coarse enough that we were able to run multiple simulations in a manageable time. Initial and open boundary conditions were provided by CMEMS Mediterranean Sea Physics Reanalysis, and the model includes 36 freshwater sources. A thorough analysis of <span>several</span> run configurations <span>revealed</span> that spatial resolution should not be the primary criteria in choosing the right forcing, as atmospheric models can be subject to significant biases. These tend to <span>strongly</span> influence the results and sometimes even cause circulation reversals. Here we present the main differences between the runs and also evaluate each of them by comparing the results with satellite observations of sea surface temperature.</p>