The northern Adriatic Sea is an important foraging ground for the loggerhead sea turtle Caretta caretta (Linnaeus, 1758) within the Mediterranean Sea. Here, stranding patterns of loggerhead sea turtles were examined over a four-year period (2019–2022) along a short (17 km) stretch of the Italian coast south of the Po River delta. A total of 355 records (alive, n = 24; dead, n = 331) were analysed, and the curved carapace lengths (CCL, notch to tip, cm) mainly reflected large juveniles and sub-adults (average CCL = 57.2 cm; 95% CI = 55.6–58.7). The month of July was identified as the critical month with the highest number of strandings, mirroring migratory processes towards this area during warmer months. The number of stranded turtles•km−1 as well as the absolute number of strandings along the short stretch of the coast might suggest this area as the most impacted in the Mediterranean Sea. This research emphasizes that human activities in the waters south of the Po River delta, particularly trawl fishing, are the primary cause of loggerhead sea turtle strandings and that tracking stranding patterns can offer valuable information about the geographic ranges, seasonal movements, and life cycles of this species.

Over the course of one year (2021), we monitored the carbon isotope composition of atmospheric CO2 at three locations in Croatia: the Adriatic port city of Rijeka (Cfa climate) and at two rural sites: Gornje Jelenje (Cfb climate) in the vicinity of a main road and clean-air site Parg (Dfb climate). Carbon isotope composition at all sites shows seasonal variation, ranging from –41.3 to 25.2‰ for Δ14C and from –13.1 to –11.3‰ for δ13C. Rijeka systematically has the lowest and Parg the highest Δ14C, and δ13C at the sites are not statistically different one from another. The Δ14C of leaves of deciduous trees reflect the trend of atmospheric Δ14C. Based on the assumption that the investigated area is under the influence of two main sources of CO2: fossil and natural (sea exchange, biosphere, and undisturbed – clean air atmospheric component) the approximate share of fossil CO2 in total atmospheric CO2 has been estimated for Rijeka (2.1 ± 1.3%) and Gornje Jelenje (1.0 ± 0.9%). Comparison of our results with the data from European CO2 sampling stations indicates strong influence of CO2 from sea and biosphere. Backward trajectories indicate a possibility of Δ14CCO2 contribution from distant EU nuclear power plants, but movement of air masses should be considered in more detail to confirm this.

The diet and feeding of juvenile common two-banded sea bream, Diplodus vulgaris, in the eastern central Adriatic Sea was studied to better understand local ecosystem dynamics in this region. Stomach contents of 140 individuals with total length (TL) between 22 and 106 mm, collected by small beach seines from February to November, were analysed. Food items identified in stomachs belonged to 16 prey groups: Copepoda, Gastropoda, Teleost eggs, Ostracoda, Polychaeta, Bivalvia, unidentified Crustacea, Amphipoda, Decapoda, Cumacea, Echinoidea, Anisopoda, Euphausiacea, Mysidacea, Branchiopoda and Isopoda. Overall, planktonic copepod crustaceans were the most important prey group (percentage index of relative importance, %IRI = 78.9), followed by gastropods (%IRI = 14.9). All other prey groups had much lower %IRI values and thus were of less importance. Fish size was an important factor influencing food composition. Planktonic copepods were the most important prey in juveniles of smaller sizes (up to 76 mm TL), whereas large-sized juvenile individuals (>76 mm TL) mainly consumed benthic prey, such as gastropods, polychaetes and bivalves. Feeding intensity was very high as indicated by the low vacuity index.

Beginning with the profound geopolitical changes created by the dissolution of the Austro-Hungarian monarchy and the creation of the Czechoslovak and Yugoslav states, this article examines how medical knowledge about maritime climate and sea-based therapies was mobilized in Czech popular touristic writing about Yugoslavia's Adriatic coast in the 1920s. The analysis of archival documents as well as non-specialist medical publications of Czech or Prague-trained doctors show that Czech tourists and curists (travelers in search of health treatments) were offered a freeform, all-encompassing therapeutic environmental approach. Inspired by Neo-Hippocratic principles, doctors stressed the importance of factors such as salt water, clean air, temperature variation, sunshine, flora, and modern facilities for disease prevention or the restoration of one's health. These doctors’ relative success in promoting the therapeutic virtues of the Adriatic Sea is explained in large part, this article argues, by a broad nexus of intertwined interests (such as the growth of tourism, concerns about public health, and the influence of Neo-Slavism) embedded in the project of transforming the Adriatic Sea into a therapeutic site.

Atlantic bonito, Sarda sarda, is one of the representatives of the Scombridae family in the Adriatic Sea. Larvae and juveniles have been found and described in the area, but no information has been published regarding adults spawning in the Adriatic Sea. To explore the strong possibility that Atlantic bonito are reproducing in the Adriatic Sea, 122 specimens of adult Atlantic bonito were collected from a purse seine net ‘palamidara’ over four seasons in 2017. The fork length of the analysed specimens varied from 37.5 to 60.8 cm, with a mean of 48.83 ± 5.59 cm, while total body weight varied between 742.68 and 3102.59 g, with a mean value of 1700.49 ± 543.82 g. Gonadosomatic index values showed an increasing trend from autumn (0.123 for males, 0.897 for females) until spring, while in the summer, they reached their maximum values (3.609 for males, 5.604 for females). This trend was also confirmed by histological and macroscopic analyses of gonads, which suggested that the Atlantic bonito spawning season is in the spring-summer in the Adriatic Sea. Hence, this confirms that this species is spawning in the Adriatic Sea.

This study combines radiocarbon (14C) analysis and sclerochronology research, an approach that to the best of our knowledge, has not yet been applied using bivalves from the Mediterranean Sea. We analyzed shells from the North Adriatic Sea: live- and dead-collected specimens of the infaunal bivalve Glycymeris pilosa and two dead-collected specimens of Glycymeris sp. According to crossdating results, growth increment time series obtained from acetate peels of the dead-collected G. pilosa (S3FP11) indicate the potential for creating longer chronologies from live and dead-collected specimens. The greatest longevity was seen in the dead-collected Glycymeris sp. specimen S3F3, estimated to be ~130 years (started growing AD 1678–1742 and died AD 1826–1860), indicating the potential to extend Glycymeris growth increment chronologies to past centuries. The highest ∆14C values obtained corresponded to the calendar year 1974. The 14C record obtained from G. pilosa correlates well with the modeled surface ocean (mixed-layer) bomb pulse curve (Reimer et al. 2009). Based on the results obtained from the shell growth increment assigned to AD 1950, the reservoir age and reservoir correction (ΔR) are 264±23 years and –6±32 years, respectively.

This study was conducted in February, April and June 2009 at three stations in the southern Adriatic. Occurrence of the dinoflagellate Noctiluca scintillans and tunicates Salpa fusiformis and Salpa maxima in high abundances for the oligotrophic open sea, indicates the importance of physical forcing (vertical mixing) and inflow of nutrient-enriched Atlantic water, due to the Bimodal Oscillating System (BiOS) mechanism, into the Adriatic Sea thus creating an environment favourable for their rapid increase. This is the first time a bloom of N. scintillans has been recorded in the open southern Adriatic (OSA). High abundance of Noctiluca and salp populations in the OSA was characterized by low abundance of phytoplankton and other zooplankton, with obvious trophic implications (reduction of food availability to crustacean primary consumers). Moreover, during the S. maxima bloom in June 2009, calanoid copepods and appendicularians were almost completely absent (<1 ind. m−3).

Perhaps the world's best-known cetacean, the bottlenose dolphin shows considerable variation in behaviour between and within populations in relation to differences in natural and anthropogenic conditions. Drivers of behavioural variation need to be identified to understand the dynamics of wild dolphin populations. Little research has been published on the bottlenose dolphin population found in the Southern Adriatic Sea. Using a set of spatial, temporal and social predictors, we aimed to investigate what variables are related to the behaviour of an under-studied population of bottlenose dolphins along the coastline of Montenegro. We present the results of a year-long study monitoring the behaviour of bottlenose dolphins along coastal Montenegro. We considered the effect of topography, seasonality and group size. A large proportion of travelling (55%) small groups (mean 4, range 1–9) in shallow waters (<50 m) was observed. We showed that seasonality alone explained behaviour best, with surface-feeding and socializing-resting increasing in autumn and winter. Group size was found to be a result of behavioural choice. We suggest seasonal changes in environmental conditions and anthropogenic pressure may explain the recorded behavioural pattern. This research points to the necessity of increased collaboration in the region to help understand complex patterns in behaviour and habitat use of local dolphin populations if effective conservation measures are to be developed.

Investigation of parasites and diseases affecting molluscs of ecological and economic interest is critical for the management of native stocks and aquaculture. In recent years, much attention has been devoted to investigating the World Organisation for Animal Health listed infectious diseases, so that communities can be prepared to attend public health emergencies and avoid severe income losses. In this context, the health status of Mytilus galloprovincialis Lamarck, 1819 was analysed in two aquaculture sites (Strunjan Bay and Piran Bay, Slovenia), and in four natural mussel beds (Adriatic Croatia International Marinas Pula and Rovinj and St Catherine, Croatia; Marina Koper, Slovenia) along the coast of the northern Adriatic Sea. The mussels were sampled in February and April 2014, and processed for histological examination of several endosymbionts and pathogens that frequently occur in mytilid mussels. Endosymbionts and pathogens were not detected in farmed mussels. Prokaryotic inclusion bodies, the protozoan Nematopsis, Ancistrocoma-like ciliates, haplosporidian-like plasmodia, turbellarian Urastoma cyprinae, and basophilic inclusion bodies were observed in digestive gland cryosections of wild mussels from the coastal region of the northern Adriatic. Fungal spores of Psilocybe sp., Ulocladium sp. and Alternaria sp. were detected between the digestive tubules based on their morphology. Diagnostic PCR did not reveal infection with Marteilia refringens during the studied period, neither in wild nor farmed mussels. We confirmed the site effects on prevalence of infected mussels. Thus, we can conclude that wild areas are more exposed to endobionts and parasites than aquaculture sites.

The Adriatic Sea and Balkan Peninsula were an important corridor for the spread of agriculture northwards and westwards from the Near East into Europe. Therefore, the pace and nature of the Mesolithic-Neolithic transition along the Adriatic coastline has important implications for the movement of new peoples and/or ideas during one of the most eventful periods in European prehistory. We present new Early Neolithic radiocarbon and stable isotope evidence from humans and animals from the Zemunica cave site in Dalmatia, Croatia. The results show that these humans date to the earliest Neolithic in the region, and they have completely terrestrial diets, where the main protein source was most likely to have come from domesticated animals. Data are then compared to previous isotope and archaeological evidence to explore models for the spread of agriculture along the eastern Adriatic coast.

Understanding animal movement patterns is not only important for providing insight into their biology, but is also relevant to conservation planning. However, in aquatic and wide-ranging species such as cetaceans, this is often difficult. The common bottlenose dolphin (Tursiops truncatus) is the most common cetacean in the northern and central Adriatic Sea and has been the focus of long-term studies in some areas. All of the studied local populations show a relatively high degree of site fidelity, but their movements, ranging patterns or connectivity are not well understood. On 24 and 26 April 2014 a single adult bottlenose dolphin was observed and photographed alive off the Slovenian coast. The same individual was found dead on the shores of Goro, Italy, on 5 May 2014, about 130 km from the two sighting locations. The well-marked dorsal fin made the identification straightforward. The dolphin was found freshly dead, suggesting it had died very recently prior to being found. This indicates that the reported movement was a real one, rather than an artefact of currents. Although single cases cannot provide the basis for making population-level inferences, our observation shows that northern Adriatic bottlenose dolphins can make substantial movements in short periods of time and suggests that such movements could be more common than currently documented. Comparisons among photo-ID catalogues and stranding events can be highly informative, as they can provide useful information with implications for the cross-border conservation of mobile marine predators.

The structure of the microbial food web was studied in six estuary areas along the eastern Adriatic coast during March, July and October 2012. Limitation by phosphorus, not nitrogen, was a common feature for all studied estuaries. Heterotrophic bacteria and autotrophic picoplankton (APP) (particularly picoeukaryotes and Synechococcus) can reach notable abundances and biomasses, suggesting potential importance of the picoplankton community in P-limited estuarine environments. The main features of the microbial community structure in these environments included: (1) higher heterotrophic biomass in comparison to autotrophic biomass within the picoplankton community; (2) general domination of picoeukaryotes within the APP community, and increase of absolute and relative biomass of prokaryotic autotrophs (Prochlorococcus and Synechococcus) in the total APP in P-limited conditions; (3) domination of Synechococcus over Prochlorococcus biomass in all studied conditions, and common spatial distribution of these two groups of cyanobacteria, which was mostly determined by concentration of phosphorus; (4) relatively high contribution (about 50%) of LNA bacteria in the total bacterial abundance; and (5) relatively high contribution (about 33%) of heterotrophic pico-flagellates in the total flagellate abundance.

Three species of bivalves, Thyasira succisa, Lyonsia norwegica and Poromya granulate, were recorded for the first time in the Adriatic Sea during surveys conducted from 2010 to 2012 on offshore relict sand bottoms at a depth range of 45–80 m.

The first record of Lebetus guilleti for the Italian seas is reported here. The finding is based on photographic records of specimens located in shallow waters off the Conero Promontory (An) along the Adriatic coast of Italy. This record expands the distribution range of this species in the Mediterranean and moves its southern limit in the Adriatic Sea 170 km further south, adding to the suspicion that the distribution of this cryptic species might be wider than previously described. Recreational SCUBA diving focused on biodiversity observations and underwater photography proved instrumental again in providing information about the presence and distribution of marine fauna, including the most easily overlooked species.

A new species of stephid calanoids copepod Stephos grieveae sp. nov. was collected from an anchialine cave on Mljet Island (Croatia). The new species can be distinguished from other Stephos spp. by a combination of the following features: last pedigerous somite slightly asymmetrical, female genital double-somite symmetrical in ventral view, about as long as wide, single operculum; antennules of both sexes are symmetrical, 24-segmented and very long, reaching almost to end of anal somite; antennal exopod 7-segmented; maxillule displays 13 armature elements on praecoxal arthrite; female fifth legs symmetrical, uniramous and 3-segmented, terminal segment very long armed with spinules distally along inner and outer margins, single small spine on anterior surface and spiniform process laterally; male fifth legs are uniramous and asymmetrically, right leg 4-segmented and left 5-segmented, segment 4 not swollen and segment 5 simple, crescent shaped and is connected to segment 4 at approximately one quarter of its length. The shorter part of segment 5 tapers into a heavy process, while the longer part forms a club-shaped, curved extension.

The Adriatic Sea, being a semi-closed and shallow basin, is more sensitive to anthropogenic impact than other areas of the Mediterranean Sea. Given the crucial role of meiofauna in the marine ecosystems, temporal series of data on this benthic assemblage are fundamental to give new insights into the health status of this basin. A data set (decade 2002–2012) on the meiofauna of two river mouths (Foglia and Metauro) close to a Natural Park (Monte San Bartolo, Central Adriatic Sea) has been analysed and related to several environmental parameters. In particular, changes in the meiofaunal structure, abundance and diversity have been investigated in order to evaluate possible variations of ecological quality status (EQS), in accordance with the Water Framework Directive. The structure of the meiofaunal assemblage appeared significantly different in the period studied, with a higher abundance of annelids in 2002 and an increase of nematodes in the following sampling campaigns. Among the faunal parameters, the Shannon and Pielou indices suggested a decline of the EQS over time, likely mainly due to the negative effect of chlorophyll-a peaks, which may highlight the influence of eutrophication phenomena and an enhancement of the organic matter supply. The lowering of the EQS of the study area suggests the need to intensify management and conservation efforts in the coastal systems, and supports the use of the meiofaunal assemblage as a useful bioindicator.