The grooved carpet-shell clam ( Ruditapes decussatus ) is a native clam species that inhabits estuaries, lagoons, and coastal flats along the Mediterranean Sea and the northeast Atlantic. This highly prized bivalve is an ecosystem engineer that provides major ecological functions, including water filtration and sediment bioturbation. A decline in production has recently been observed in several areas of southwestern European and the Mediterranean region; however, data documenting this phenomenon remain scarce and are largely unpublished. To address this knowledge gap, we conducted a study based on official statistics, the expertise of 24 marine ecosystem experts from eight countries covering 17 coastal sites, and a preliminary literature map. This approach enabled the development of an expert-informed regional perspective on the reported declines of R. decussatus , as well as a synthesis of the regulatory measures and restoration actions implemented across the study area. The findings indicate a sharp decline in both production (−32 to −100%) and stocks (≈ −80%) over the past two decades. The onset of the decline varied among sites, occurring between 2003 and 2024. According to the participating experts, the main suspected drivers of the decline were disease, overfishing, competition with alien species, and climate change. The most common regulatory measures were minimum conservation reference sizes, closed fishing seasons, and licenses. Only a few restoration projects were identified, focusing on restocking through seeding, the collection of natural broodstock, harvesting natural spat or substrate modification. This study provides a preliminary overview of the seemingly widespread decline of R. decussatus across the southwestern European and Mediterranean region and highlights the need for coordinated research to elucidate the causes of this reported decline, as well as for restoration actions to support the recovery of this native species.

Elasmobranch species are the direct or accidental catch of fisheries and can have a commercial importance. In the Mediterranean Sea, a long-term period of overfishing brought several demersal elasmobranchs to be depleted and threatened by extinction, due to vulnerability related to their life history traits. In such exploited species, information on genetic diversity and connectivity is lacking and should be collected to identify management units. In this study, we focused on two threatened smooth-hound species, Mustelus Mustelus (Linnaeus, 1758) and M. punctulatus (Risso, 1827), whose abundance and distribution showed a decline at the Mediterranean regional level in the last century. Thanks to an opportunistic yet extensive sampling, we obtained the largest subregional collection of specimens for genetic analysis so far. In total, 86 and 214 specimens of M. mustelus and M. punctulatus were collected between 2016 and 2020 in the Adriatic Sea and the Strait of Sicily. We assessed the population genetic structure typing 17 microsatellites and sequencing part of the mitochondrial control region in both species. We observed a substantial nuclear and mitochondrial genetic structure when accounting for the geographical sampling area for both species. Our results indicate the presence of at least two genetic stocks for each of the two species: one in the Strait of Sicily and the other in the Adriatic Sea. This study provides valuable data that should be integrated into a broader approach to define management units, improving the development of an effective management strategy for these threatened species in the Central Mediterranean Sea.

In September 2021, as part of the Italian Arctic research programme, a multidisciplinary cruise along the 75th parallel north through the Greenland Sea Gyre was conducted aboard the Italian icebreaker Laura Bassi in the framework of the CASSANDRA project, which also contributed to the Synoptic Arctic Survey (SAS) 2020/22. The cruise took place during the period of the lowest summer sea ice extent ever measured. The data show strong horizontal gradients with temperatures between 1.5 and 9.0 °C and salinity between 30 and 35. Warm and salty Atlantic Water (AW, θ > 3.0 °C, S around 35) dominates on the eastern side of the transect in the upper 500 m with surface temperatures of 4.5–9.0 °C, while Polar Water (PW, θ < 0 °C, S < 33) occupies the surface layer (50–80 m) in the west. The intermediate layer (100–500 m) consists of mixed water, and below 500 m the deep water of the Greenland Sea and the Norwegian Sea predominates. The oxygen enrichment is higher in the intermediate layers, while the values in deep layers and western regions are lower (<300 µmol kg−1). A stratified upper layer (30–50 m deep) with low surface nutrients, especially nitrate, is observed, while an accumulation of silicate occurs in deep water masses. The surface water in the eastern part of the transect has high pHT and total alkalinity values due to photosynthesis and the presence of salty AW, while the fresh PW in the west has a lower alkalinity. Respiratory activity and organic matter concentrations (particulate/dissolved organic carbon) vary horizontally at the surface, decrease with depth, and increase slightly near the seafloor. A west–east gradient is also observed for δ18O and δD, with the ratios indicating the influence of freshwater at the surface near the Greenland coast. The abundance of prokaryotes decreases from the photic zone (<100 m depth) to the sea floor. Carbohydrates and carboxylic acids are identified as well-utilised polymers at every station and in every layer. Overall, the microbial enzyme patterns show a decrease from the surface to deeper layers, with some hotspots of metabolic activity at 20–40 m and in the aphotic layer. The enzyme patterns vary spatially, with activity peaks at the ends and in the middle of the transect. Phytoplankton biomass, expressed as chlorophyll a, varies across the transect, with higher values at the westernmost and easternmost stations. The micro-phytoplankton fraction dominates in PW, while the nano-phytoplankton fraction predominates in AW, even at the interface between the two water masses. Data of phytoplankton communities show low abundances and a dominance of nano-sized organisms, with diatoms being more abundant in the western part. Microzooplankton represents an important fraction of the planktonic community in this area, with tintinnids being the most important groups along the transect. Micrometazoans and aloricate ciliates are more abundant in the AW, resulting in higher biomass values at the eastern stations. Copepods are the most abundant mesozooplanktonic taxon both at the surface and in the upper 100 m water layer (97 % and 94 % of total mesozooplankton abundance, respectively), mainly represented by the genus Calanus. The data are publicly available at the Italian Arctic Data Centre (IADC), see https://doi.org/10.71761/c082c3ca-40bf-42b1-a61a-7b3697ab2c5a (Bensi et al., 2024), https://doi.org/10.71761/f7474404-3331-43e5-883b-25755e94956d (Azzaro et al., 2024).

Transitional environments have great ecological value and high productivity, and many species can benefit from their sheltered conditions and food resources. In this study, we performed for the first time a fish-targeted eDNA metabarcoding of the 12S rRNA gene at 16 sites broadly covering the different water bodies of the Marano and Grado Lagoon (northern Adriatic Sea) in two seasons. The eDNA was collected at the same time as the beach seine net, allowing a direct comparison of the two approaches.With eDNA we detected 34 species, covering all the functional guilds occurring in the lagoon. Species of regional interest, that uses the area as a nursery and feeding ground, and diadromous species, highlighting the ecological connectivity between freshwater and marine habitats, were found. While some species were constantly present (e.g. Atherina boyeri, Sparus aurata), others (Squalius cephalus, Platichthys flesus) were influenced by salinity (higher in Grado and lower in Marano), which was confirmed as the main ecological driver in this environment. The comparison with traditional methods, which identified 18 species (11 of which were detected with both approaches), showed that eDNA is very sensitive in detecting most of the biodiversity in the lagoon with a limited sampling effort. Few relevant species (Chelon saliens, Knipowitschia panizzae) lacked reference sequences, which need to be implemented in the databases. Our study represents a significant advance in the understanding of lagoon fish biodiversity and ecological dynamics and contributes to the improvement of management strategies in these ecologically sensitive habitats.

The sea walnut, Mnemiopsis leidyi, has invaded and expanded throughout the whole Mediterranean Sea basin. Large blooms were recorded also in the Venice Lagoon (Italy), an ecosystem rich with biodiversity which supports multiple services, including artisanal fishery production. To investigate M. leidyi impacts on lagoon artisanal fisheries, we combined fishers’ local ecological knowledge, fishery landing time series analysis, and field sampling. Firstly, we interviewed artisanal fishers to date the blooms of M. leidyi. Secondly, we analyzed long-term fishery landings records to detect whether changes in landings quantity and composition were related to the ctenophore invasion. Thirdly, we sampled catches of the lagoon fyke nets. This interdisciplinary approach overcame the weaknesses of single methodologies and allowed us to reconstruct the temporal phases of M. leidyi invasion in the Venice Lagoon. Moreover, our results indicate that the lagoon landings significantly declined with the blooms, paralleled by the increase of water temperature. Finally, we showed that the mechanical obstruction of the nets, caused by the massive ctenophore blooms, strongly impacts fishing activities. Our results are a first step in assessing the short and long-term impacts of this invasive species on lagoon ecosystems, including its socioeconomic consequences, whose better understanding is fundamental to inform mitigation and adaptation measures.

Food availability is thought to exert a bottom-up control on the population dynamics of small pelagic fish; therefore, studies on trophic ecology are essential to improve their management. Sardina pilchardus is one of the most important commercial species in the Adriatic Sea, yet there is little information on its diet in this area. Adult sardines were caught in the Gulf of Trieste (northern Adriatic) from spring 2006 to winter 2007. Experimental catches conducted over 24-h cycles in May, June and July showed that the sardines foraged mainly in the late afternoon. A total of 96 adult sardines were analysed: the number of prey varied from a minimum of 305 to a maximum of 3318 prey/stomach, with an overall mean of 1259 ± 884 prey/stomach. Prey items were identified to the lowest possible taxonomical level, counted and measured at the stereo-microscope. Overall, sardines fed on a wide range of planktonic organisms (87 prey items from 17 μm to 18.4 mm were identified), with copepods being the most abundant prey (56%) and phytoplankton never exceeding 10% of the prey. Copepods of the Clauso-Paracalanidae group and of the genus Oncaea were by far the most important prey. The carbon content of prey items was indirectly estimated from prey dry mass or body volume. Almost all carbon uptake relied on a few groups of zooplankton. Ivlev’s selectivity index showed that sardines positively selected small preys (small copepods < 1 mm size), but also larger preys (such as teleost eggs, decapod larvae and chaetognaths), confirming their adaptive feeding capacity.

“New records of rare species in the Mediterranean Sea” (October 2021)

The paper presents a database of information on wrecks, natural and artificial reefs located in the Adriatic Sea, collected within the framework of the Interreg Italy–Croatia project ADRIREEF – Innovative exploitation of Adriatic Reefs in order to strengthen Blue Economy. The data collection lasted more than 1 year and included three surveys and a wide literature review. After being collected, data were harmonized and, where possible, made machine-readable. Moreover, data were widely metadated, published in a WebGIS (https://adrireef.github.io/sandbox3/, last access: 3 May 2021), and shared as open data in EMODnet (European Marine Observation and Data Network) Data Ingestion Portal through the SEANOE repository (Ferrà et al., 2020; https://doi.org/10.17882/74880). The database is composed of 285 three-dimensional records, each one described by 51 attributes. Parameters are clustered in four main groups: identification, reef description, site description, and management/exploitation information. Available literature (scientific and/or grey) was also included in the database and linked to the corresponding site.

Sharks are among the oldest residents of the planet, they possess a unique value as top predators and constitute irreplaceable elements of marine ecosystems. Unfortunately, contemporary narratives widely presented in popular mainstream media have attached an utterly negative connotation to sharks, propagating an unsubstantiated and fabricated image of them as implacable and voracious predators. Recently a lot of attention is devoted to understanding the public perception towards sharks in order to promote their conservation given that a quarter of all shark species are facing extinction. This work assessed the current attitude of the public towards sharks on a global scale, utilizing modern technology through a single protocol that explored the importance of factors like culture, history, or educational level in shaping attitudes. We collected 13,800 questionnaires from 137 countries, with 25 countries presenting more than 100 answers each, representing in total 92% of the filled questionnaires. A generally positive attitude towards sharks emerged from our study, influenced significantly by several factors including knowledge and participation in marine conservation projects. Interestingly, shark attacks emerged as an important factor, with countries having high numbers of shark attacks exhibiting a highly positive attitude towards sharks, potentially because their citizens are more aware of the issue and the importance of sharks for the marine ecosystems. Guidelines for shifting public attitude towards sharks and consequently advancing shark conservation were also drawn.

The Mediterranean Sea has a long-lasting history of fishery exploitation that, together with other anthropogenic impacts, has led to declines in several marine organisms. In particular, elasmobranch populations have been severely impacted, with drastic decreases in abundance and species diversity. Based on their experience, fishers can provide information on marine species occurrence, abundance and behavioural traits on a long-term scale, therefore contributing to research on the poorly studied biological aspects of elusive or rare elasmobranch species. In this study, for the first time, the use of the Local Ecological Knowledge (LEK) of fishers was applied to study the behavioural traits of sharks, rays and skates in 12 FAO-GFCM geographical sub-areas (GSAs) of the Mediterranean Sea. This study found both new insight and proved the reliability of LEK-based catch seasonality, reflecting seasonal movements, by comparing LEK-based findings and available literature on five elasmobranch taxa (Mustelus spp., Squalus acanthias, Raja spp., Myliobatis aquila and Scyliorhinus stellaris) in the Adriatic Sea and 7 taxa (Mustelus spp., Raja spp., Prionace glauca, Scyliorhinus canicula, Torpedo spp., Pteroplatytrygon violacea and Isurus oxyrinchus) in the remaining Mediterranean GSAs. In addition, LEK provided new insights into a novel comprehensive representation of species aggregations (Mustelus spp., S. acanthias, M. aquila and S. canicula) in the sampled GSAs and supplied the first descriptions of the size, number of individuals and sex composition of the aggregations. When the limits and shortcomings of LEK-based research are considered, this methodology can be a complementary and cost-effective tool used to study elasmobranchs in either a data-poor scenario or a scenario in which a baseline is missing. LEK can also be useful for the evaluation and inclusion of fishers’ perceptions on bottom-up management and to provide important evidence for conservation plans.

The recent northward expansion of the round sardinella Sardinella aurita in the Mediterranean Sea has been documented as a consequence of rising sea temperature. At the same time, declines in sardine and anchovy biomass have been observed in the NW Mediterra nean Sea, necessitating an assessment of whether the expansion of round sardinella may affect sardine and anchovy populations. Here, we combined stomach content and isotopic analyses to describe the trophic habits of round sardinella in the NW Mediterranean Sea and its trophic relationships with 2 sympatric small pelagic fish, European anchovy Engraulis encrasicolus and European pilchard Sardina pilchardus. Results revealed changes in the diet of round sardinella during the year. In summer, the most important prey were copepods (Acartia spp.) and cladocerans (Penilia avirostris). During winter, the diet was composed mainly of copepods and tunicates (mainly appendicularians), but microplankton was also numerically important in adult diets. In contrast to previous studies, during spring, round sardinella principally fed on salps (Thaliacea). To our knowledge, this is the first time that salps have been identified as an important prey for round sardinella. When compared to coexisting small pelagic fish, we found that round sardinella adults had a different trophic niche than anchovy and sardine. In contrast, round sardinella juveniles partially overlapped the trophic niche with the juveniles of the other 2 species. Therefore, the range expansion of round sardinella probably would not affect sardine and anchovy populations. Only in a situation of food limitation could juveniles of round sardinella compete with and affect both sympatric species. Our results provide new insights into the ecological role of this range-expanding species in the NW Medi terranean Sea, and highlight the importance of gelatinous zooplankton as prey.

Zooplankton plays a pivotal role in marine ecosystems and the characterisation of its biodiversity still represents a challenge for marine ecologists. In this study, mesozooplankton composition from 46 samples collected in summer along the western Adriatic Sea, was retrieved by DNA metabarcoding analysis. For the first time, the highly variable fragments of the mtDNA COI and the V9 region of 18S rRNA genes were used in a combined matrix to compile an inventory of mesozooplankton at basin scale. The number of sequences retrieved after quality filtering were 824,148 and 223,273 for COI and 18S (V9), respectively. The taxonomical assignment against reference sequences, using 95% (for COI) and 97% (for 18S) similarity thresholds, recovered 234 taxa. NMDS plots and cluster analysis divided coastal from offshore samples and the most representative species of these clusters were distributed according to the dominant surface current pattern of the Adriatic for the summer period. For selected sampling sites, mesozooplankton species were also identified under a stereo microscope providing insights on the strength and weakness of the two approaches. In addition, DNA metabarcoding was shown to be helpful for the monitoring of non- indigenous marine metazoans and spawning areas of commercial fish species. We defined pros and cons of applying this approach at basin scale and the benefits of combining the datasets from two genetic markers.

Identification of potential spawning and nursery areas of European anchovy (Engraulis encrasicolus) represents an essential step in the management of a resource which is of fundamental importance both for fishery and pelagic trophic web. Egg and larvae occurrence from ichthyoplankton surveys (2012 - 2015) in the South Western Adriatic Sea were examined to understand the mechanisms that control their distribution. Egg and larvae densities varied through the years with the highest values recorded in 2012 and the lowest in 2014. Positive correlations between eggs and larvae with zooplankton were observed. When quotient analysis was used to find relations with environmental and biological variables, the results pointed out an egg preference for depth between 91 and 120 m and an avoidance between 11 and 30 m. Moreover, egg avoidances for high values of chlorophyll-a (> 0.52 mg m-3) and low values of zooplankton biomass (< 199 mg m-2) were highlighted. On the other hand, different ranges of habitat preferences and avoidances were observed for larvae: preference range of depth between 11 and 60 m and avoidance > 151 m; preference for high zooplankton biomass (> 1000 mg m-2) and avoidance for low biomass (< 299 mg m-2). These correlations and the quotient values suggest that egg and larvae distribution in the South-Western Adriatic Sea is mainly driven by food availability and depth.

International Council for the Exploration of the Sea (ICES) - North Pacific Marine Science Organization (PICES) International symposium : Drivers of dynamics of small pelagic fish resources, 6-11 March 2017, Victoria, BC, Canada

Anchovies represent the largest world's marine fish catches and the current threats on their populations impose a sustainable exploitment based on sound scientific information. In the European anchovy (Engraulis encrasicolus), the existence of several populations has been proposed but a global view is missing. Using a multidisciplinary approach, here we assessed the divergence among different ecotypes and its possible causes. SNPs have revealed two functionally distinct ecotypes overlapping in the Central Mediterranean, with one ecotype confined near the river estuaries. The same SNPs outliers also segregated two distinct populations in the near Atlantic, despite their large spatial distance. In addition, while most studies suggested that adaptation to low salinity is key to divergence, here we show that the offshore ecotype has higher environmental tolerance and an opportunistic feeding behaviour, as assessed by the study of environmental conditions, anchovy diet and trophic levels, and passive egg dispersal. These results provide insights into the anchovy evolutionary history, stressing the importance of behaviour in shaping ecotypes.

From time immemorial we have conceived of our relationship to other human beings and, by extension, to non-humans, as a permanent state of warfare, punctuated by fleeting periods of truce. Such an approach has colored our view of plants and animals as beings constantly engaged in a struggle against one another, in a contest for the “survival of fittest,” both individually and at the level of the species. According to this perspective, humanity merely follows a generalized condition of life as a ruthless fight for survival that justifies dominating and exploiting those who might further our goals and slaughtering the ones who stand in the way. In this paper, I suggest that we look at interspecies relations from the perspective of peace and not war. Can the “wolf dwell with the lamb / and the leopard [...] lie down with the young goat,” as the Old Testament metaphorically would have it in its image of a righteous Earth? Can humans live peacefully side by side with non-human beings? I will avail myself of theories of cosmopolitanism to delineate the notion of interspecies peace as an alternative to the current war of all against all that characterizes our relationship to other living beings.

The present study provides the first estimate of the daily ration for a goby species in the Mediterranean Sea, using a new approach to determine the mass of fish stomach contents through the sum of individual prey dry mass derived indirectly from prey size. Diel feeding activity and daily ration of the pelagic goby Aphia minuta were studied under natural conditions in the coastal waters off Comacchio (Northwestern Adriatic Sea) during the spring season. A total of 318 individuals of A. minuta , collected by 14 trawls carried out on 4 consecutive days, was examined for gut contents. The diel pattern of the vacuity index and the stomach fullness index indicated that A. minuta has nocturnal feeding behaviour. The daily ration, computed over a period of 16 h, was equivalent to 2.23% wet body mass.