Search Results (68)

Posidonia oceanica (L.) Delile is a seagrass endemic to the Mediterranean Sea and a significant contributor to human well-being through a variety of ecosystem functions, such as carbon cycling. Despite its ecological significance, most methods for estimating leaf biomass in this species are either destructive or expensive. In this study, 2500 individual leaves from 351 shoots of Posidonia oceanica were collected, across 16 sites in the Ligurian Sea, over two time periods (2016–2018 and 2024–2025), and analyzed for total leaf area and dry weight. An allometric equation following a power-law structure was derived using linear mixed-effects models and it was later validated via 10-fold cross-validation. Although some variations in the intercept term were observed, the allometric scaling structure remained consistent across space and time, providing the first robust species-specific allometric tool to estimate P. oceanica biomass, forming the basis of a proposed non-destructive protocol for meadow-scale biomass estimation. Full article

The UNESCO World Heritage coastal zone of Cinque Terre (Liguria, northern Italy) is increasingly threatened by ongoing sea-level rise. To assess expected sea levels up to 2150 CE under the IPCC Sixth Assessment Report (AR6), we carried out a first evaluation of potential coastal flooding for Monterosso and Vernazza under different Shared Socioeconomic Pathways (SSPs), integrating high-resolution topography and bathymetry, geodetic data, historical tide-gauge evidence, and storm-surge modeling. The historical sea-level analysis indicates a non-stationary rising trend for the Ligurian sector. Relative sea-level rise (RSLR) projections were computed for SSP1-2.6, SSP3-7.0 and SSP5-8.5, including local land subsidence, and were used to map the potential inundated areas for 2030, 2050, 2100, and 2150 CE. In 2150, projected RSLR is expected to range from 0.60 m to 1.17 m, corresponding to flooded surfaces of 9931 m² and 22,079 m² in the SSP1-2.6 and SSP5-8.5 scenarios, respectively. Because site-specific long-term run-up observations are not available for formal calibration at the two study sites, the storm-surge simulations are interpreted as scenario-based hazard envelopes. Even within this framework, storm surges with return times of 1 and 100 years in the SSP5-8.5 scenario cause maximum wave run-up in the range of 5.12 m and 13.36 m. The results show that narrow pocket beaches and low-elevation harbor areas are the most critical receptors and that adaptation measures should focus on quay elevation, drainage/backwater management, and the protection of transport and tourism infrastructures. Full article

Posidonia oceanica meadows are among the most valuable coastal ecosystems in the Mediterranean Sea, providing key ecological functions and socio-economic benefits. Despite conservation efforts, these meadows declined markedly throughout the late 20th century due to cumulative human pressures, although their condition has stabilised more recently under protection, and natural recolonization has even begun in some areas. In this context, active restoration through transplantation has expanded considerably, particularly in response to recent policy initiatives, and is now contributing to the recovery of these ecosystems. However, long-term monitoring to assess active restoration success remains scarce. This study revisits one of the earliest P. oceanica transplantation interventions, initiated in 1996 in front of the tourist harbour of Rapallo (NW Mediterranean), and evaluates its status after nearly 30 years. Surveys conducted in 2019 and 2024 confirmed the persistence of the transplanted meadow. The restored area increased from approximately 20 m² at establishment to 26.9 m² in 2024, and shoot density reached values comparable to well-developed natural meadows in the region. The observed long-term structural stability highlights the need to assess restoration outcomes over decadal timescales. This case study also suggests that fine-scale site conditions, including hydrodynamic shelter and adequate light availability, can strongly influence long-term restoration success. Full article

Cladocora caespitosa is an endemic hermatypic scleractinian in the Mediterranean Sea, currently threatened by both environmental and anthropogenic pressures, whereas Oculina patagonica is a cryptogenic hermatypic scleractinian that is expanding across the basin. This study provides the first assessment of co-occurring natural populations of these shallow-water taxa, examining their population structures, habitat preferences, and responses to environmental stressors based on SCUBA surveys conducted in the summers and autumns of 2022 and 2023. Both species were dominated by medium- to large-sized colonies, indicating relatively stable population structures, with C. caespitosa exhibiting significantly higher densities than O. patagonica. Both scleractinians showed a preference for sub-vertical and vertical rocky substrates, although O. patagonica appeared more tolerant of horizontal surfaces. Disease events were more frequent and severe in C. caespitosa, particularly affecting larger colonies during autumn 2022, whereas O. patagonica showed lower incidence and greater resilience overall. Temporal comparisons suggest that O. patagonica may act as a strong competitor to C. caespitosa; however, both species demonstrate a considerable capacity for recovery, likely due to adaptation to high-stress environments. These findings highlight key differences in ecological strategies and vulnerability to environmental stressors, emphasizing the need for targeted conservation approaches to preserve Mediterranean shallow-water coral communities under accelerating climate change. Full article

Historically, the Mediterranean Sea has been an area of cultural exchange and maritime commerce. One out of many submerged archaeological sites is the Roman shipwreck that was discovered in 2006 off the coast of Santo Stefano al Mare, in the Ligurian Sea, Italy. The wreck was dated to the 1st century B.C. and consists of a well-preserved cargo ship of Roman amphorae that were likely used for transporting wine. In this study, we present the results of the first underwater survey of the wreck using an Autonomous Underwater Vehicle (AUV) industrialized by Graal Tech. The AUV was equipped with a NORBIT WBMS multibeam sonar, a 450 kHz side-scan sonar, and inertial navigation systems. The AUV conducted multiple high-resolution surveys on the wreck site and the collected data were processed using geospatial analysis methods to highlight local anomalies directly related to the presence of the Roman shipwreck. The main feature was an accumulation of amphorae, covering an area of approximately 10 × 7 m with a maximum height of 1 m above the seabed. The results of this interdisciplinary work demonstrated the effectiveness of integrating AUV technologies with spatial analysis techniques for underwater archaeological applications. Furthermore, the success of this mission highlighted the potential for broader applications of AUVs in the study of the seafloor, such as monitoring seabed movements related to offshore underground energy storage or the identification of objects lying on the seabed, such as cables or pipelines. Full article

The Ligurian Sea, located in the northwestern Mediterranean, is undergoing a dramatic shift in fish biodiversity due to climate change and species immigration. This study adopted a citizen science approach to provide new data on the current distribution of rare, thermophilic, and alien fish species in the Ligurian Sea. Observations were collected through social networks and personal acquaintances, involving fishermen, divers, and fishmongers. We obtained a total of 47 records, encompassing 18 species belonging to 18 different fish families. Considering existing literature, some species appear to prefer this part of the Mediterranean Sea, likely due to the Ligurian Sea’s unique hydrodynamic and oceanographic conditions that support nutrient-rich environments. Others appear to be less common in the region, probably due to the lower temperatures of the Ligurian Sea compared to other Mediterranean sectors. Our findings emphasize the dual and controversial role of the Ligurian Sea as a refuge for cold-adapted species and a hotspot for thermophilic invaders. Moreover, this research highlights the role of citizen science in complementing traditional survey approaches, providing an efficient tool to monitor many taxa across several diverse ecological niches. Full article

The Pelagos Sanctuary hosts eight resident cetacean species. Genetically different from Atlantic populations, their conservation is essential to preserve the whole biodiversity of the Ligurian Sea. The NATURA 2000 network is currently identified as one of the most efficient conservation tools due to its legally binding nature; however, its effectiveness for cetacean preservation is still unclear. The study used data systematically collected within the Pelagos Sanctuary from 2008 to 2021 by the FLT Med Net and the LIFE Conceptu Maris projects to investigate cetaceans distribution, Richness and diversity related to the existing protected areas. Of the 423 hexagons considered, only 21.28% of the study area was covered by French NATURA 2000 sites and 9.22% by Italian sites. French NATURA 2000 sites had the highest coverage of weighted Encounter Rate (ER_w) and biodiversity values. Only three species showed statistically significant differences between the French and Italian protected and non-protected hexagons, and biodiversity showed no significant difference. Only T. truncatus had higher median over Italian protected hexagons. The Pelagos Sanctuary still lacks offshore NATURA 2000 sites, especially in Italian waters. For this reason, areas to amplify the Network aimed at increasing cetacean and biodiversity conservation were highlighted in the results of this study. Full article

Mesopelagic fish belonging to the families Gonostomatidae, Phosichthyidae, Sternoptychidae, Stomiidae, Paralepididae, Myctophidae, Evermannellidae, Microstomatidae, and Nemichthyidae were sampled using an Isaacs Kidd Midwater Trawl (IKMT) in the Ligurian Sea, Northwestern Mediterranean, the core of the Cetacean Sanctuary established in 2001. In September–October 2002 and September 2003, 31 species of mesopelagic fish were captured in oblique hauls from 800 m depth to the surface. The mesopelagic fish fraction represented about 22% of the collected biomass, dominated by two main species of the genus Cyclothone, representing 93.8% of total abundance, followed by Argyropelecus hemigymnus and Lampanyctus crocodilus. The presence of Valenciennellus tripunctulatus was a new record for the study area. The family Myctophidae was the most represented in terms of number of species (n = 13). The abundance and biodiversity of mesopelagic fishes were influenced by the sampling period and oceanographic conditions, specifically temperature. While no diel vertical migrations could be observed, day and night samples revealed different compositions of juveniles and adults of Benthosema glaciale and Ceratoscopelus maderensis. The broad size range of specimens sampled confirmed that adult individuals of Chauliodus sloani and Lampanyctus crocodilus can inhabit and forage within the water column beyond the slope rather than exclusively near the bottom. Full article

Satellite altimetry observations are checked against in situ measurements to assess the capability of this remote sensing technique to describe the surface circulation in the Ligurian Sea. CTD profiles were collected during five oceanographic campaigns from 2017 and 2024 along the satellite track Jason 044, crossing the Ligurian Sea from the Corsica Channel to the coast close to Genoa. Eight months of ADCP surface currents from a fixed mooring were also used for the comparison with altimetric-derived geostrophic currents. Moreover, the possible contribution of ICESat-2 to oceanographic studies in the area is investigated. Altimetric measurements successfully reproduce the basic circulation features of the region and their seasonal variation and, despite the different nature of the used systems, can be well integrated with in situ observations. The results from the direct comparison with daily mean values of ADCP surface currents reported an RMSD of the same order as the standard deviation, which is consistent with similar investigations in other areas but evidences the need to define more appropriate metrics and methods. Full article

An analysis of 483 remotely operated vehicle (ROV) dives carried out along the Italian coast on hard substrata at mesophotic depths (40–200 m) allowed an overview of the rich sponge diversity (53 taxa) of the deep continental platform to be obtained for the first time. About 40% of the potential actual species diversity was recognisable using ROV, suggesting that this group is among the richest yet underestimated using this technology in contrast to other megabenthic taxa. Additionally, the study allowed us to gather data on the current basin-scale distribution and bathymetric limits of five common and easily identifiable demosponges with up to 55% occurrence in the explored sites: Aplysina cavernicola, the group Axinella damicornis/verrucosa, Chondrosia reniformis, Foraminospongia spp., and Hexadella racovitzai. Four of these latitudinal distributions were characterised by high occurrence in the Ligurian Sea and a progressive decrease towards the south Tyrrhenian Sea, with an occasional second minor peak of occurrence in the Sicily Channel. In contrast, Foraminospongia spp. showed a maximum occurrence on the offshore reliefs and a second one in the North–central Tyrrhenian Sea, while it was almost absent in the Ligurian Sea. Trophic and biogeographic reasons were discussed as possible causes of the double-peak distributions. The vertical distributions support a more consistent occurrence of all considered taxa in deeper waters than previously known. This suggests that they may more typically belong to the mesophotic realm than the shallow waters, owing to a more extensive sampling effort in the deeper depth range. The five target taxa are typical or associated species of seven reference habitats in the recently revised UNEP/SPA-RAC classification. However, they may create such dense aggregations that they should be listed as new facies in the abovementioned classification. Full article

Data collected by C. Re. Di. Ma over a 3-year period (2020–2022) were considered to assess anthropic pressure on cetaceans living in the Ligurian sea. Out of a total of 37 stranded cetaceans, a complete post mortem examination was performed on 23 cases. Of these, 14 were further selected considering at least one of these conditions: (i) confirmed, probable, or suspected interaction with fishing activities through the application of a standardized diagnostic framework (7/14; 50%), (ii) toxicological stress through the evaluation of OCs hazardous levels (14/14; 100%), and (iii) terrestrial pathogen-associated disease (systemic infection and/or associated lesions) (7/14; 50%). For 9 animals out of a total of 14 selected, the cause of death was classified as natural (6/14; 42,8%), anthropic (3/14; 21,4%), or not determined (5/14; 35,7%) based on gross and histological pathology and ancillary testing. These findings extend our knowledge of the anthropic pressure to which cetaceans stranded along the Ligurian coastline are subjected from a multidisciplinary point of view. Full article

This paper outlines the history of scientific research developed in the Portofino Promontory, located in the centre of the Ligurian Sea. The chronicles span over two centuries, from the late 18th century to the present day. Portofino is now recognised as one of the best-known areas in the world regarding marine biological communities and their temporal dynamics, particularly in relation to current climate changes. In addition, since 1999, with the establishment of the Marine Protected Area, significant research related to marine environment conservation has developed in Portofino. The role of the University of Genoa, the Natural History Museum, other important institutions, and the researchers involved in the Portofino area has been outlined. Full article

The constellation fish, Valenciennellus tripunctulatus, is a small mesopelagic teleost typically found in equatorial and temperate waters worldwide, although the species has been also rarely recorded in the Mediterranean Sea (less than 20 specimens from the available literature since 1918). The Mediterranean records have been documented for the Strait of Messina, the southern Tyrrhenian Sea, the Ligurian Sea and the Adriatic Sea. The present paper offers an updated review on the occurrence of V. tripunctulatus in the Mediterranean basin and provides data on three new specimens, collected in the Strait of Messina between April 2010 and March 2024. Furthermore, we also report information from two individuals found in March 1992 and February 2017, respectively. Overall, the standard length of these specimens ranged from 24.1 to 28.2 mm, whereas weight varied from 0.18 g to 0.20 g. Morphometric and meristic data were reported, and this analysis revealed few differences between examined individuals in the number of PV (ventral series anterior to pelvic fin base) and AC (from anal fin origin to caudal fin base) photophore series. The relationship between total length and standard length (SL = 0.75 × TL + 2.98), total length and head length (HL = 0.17 × TL + 1.47) and standard length and head length (HL = 0.23 × SL + 0.88) showed high correlation values. Considering the lack of data on this species in the Mediterranean, updating morphometric, meristic, biological, ecological and distribution information is very important for taxonomic purposes and useful in understanding the characteristics of the regional population and eventual differences between Mediterranean stock(s) and those from other oceanic areas. Full article

Photobacterium damselae subsp. damselae (Pdd) is an increasingly common bacterium in post-mortem diagnostics of beached marine mammals, but little is known about its precise etiological responsibility. To estimate the prevalence of Pdd in stranded cetaceans from 2017 to 2022 on the Ligurian coast (Pelagos Sanctuary), we tested tissues from 53 stranded individuals belonging to four cetacean species. DNA extracts from cetacean tissue were screened using a polymerase chain reaction (PCR) assay targeting the Pdd ureC gene. Positive samples were screened by PCR for dly, hlyA_pl and hlyA_ch hemolysin genes, which were confirmed by sequencing. Twenty-two out of 53 (41.5%) cetaceans analyzed by PCR were confirmed for Pdd DNA in at least one tissue among those analyzed. Five of these cetaceans were positive for at least one of the hemolysin genes tested. In all Pdd-positive cetaceans, other pathogens that were considered responsible for the causa mortis of the animals were also found. The results provide new information on the spread of Pdd in cetaceans and support the thesis that Pdd might be an opportunistic agent that could contribute to worsening health conditions in subjects already compromised by other pathogens. However, further studies are needed to investigate and deepen this hypothesis. Full article

Over the past thirty years, the red gorgonian Paramuricea clavata in the Mediterranean Sea has faced increasing threats, including heat waves and human activities such as artisanal and recreational fishing. Epibiosis on damaged gorgonian colonies is generally used as an indirect indication of stressed conditions. The density and height of P. clavata and the percentage of colonies affected by epibiosis and entangled in lost fishing gear were monitored to investigate the phenomenon and its trend over time in the Ligurian Sea. Analyses were based on transects collected during ROV campaigns between 2015 and 2022 at depths of 33–90 m. A strong correlation was observed between fishing efforts in the study area and the level of epibiosis. Maximal percentages of colonies affected by epibiosis and entanglement were recorded at depths of 50–70 m. Temporally, marine heat waves before 2019 were identified as the primary cause of damage to P. clavata. The decrease in epibiosis percentages after 2019, despite the 2022 heat wave, may be due to a quick recovery ability of the populations and a reduction in fishing activities during the COVID-19 lockdown in 2020. Long-term monitoring programmes are essential to understand the changes in marine benthic communities exposed to different stressors. Full article