The present study reports the first confirmed occurrence of the yellowbar angelfish Pomacanthus maculosus (Forsskål, 1775) in Hellenic waters, extending the known Mediterranean distribution of this West Indian Ocean species. A single adult specimen was collected by spearfishing on 15 October 2025 from shallow coastal waters off southern Crete. Identification was based on distinctive coloration patterns, morphological characteristics, and meristic counts. The habitat consisted of steep rocky substrates adjacent to sandy plains, aligning with the known ecological preferences of the species. Possible introduction pathways are examined, with aquarium release or escape and natural westward range expansion from established Levantine populations considered as non-exclusive scenarios. This record bridges an apparent distributional gap between eastern and central Mediterranean records, which may partly reflect limited detectability due to the species’ cryptic habits rather than true absence. The finding underscores the importance of Crete as a strategic monitoring area for detecting the arrival and potential spread of marine non-indigenous species within Hellenic waters. Continued surveillance is essential to assess establishment and potential ecological implications.

The gold coral, Savalia savaglia , is generally considered a rare parasitic parazoanthid mainly found in the Mediterranean Sea, with occasional records in the Atlantic Ocean. Recently, more has come to light regarding its distribution patterns, genetic information, and habitat due to the increased research focus. Listed as ‘Near Threatened’ on the IUCN Red List, S. savaglia requires continued monitoring, and updated assessments of its distribution are crucial. Here, we compile recent data and current knowledge on this species, highlighting both confirmed findings and unresolved questions, like the question of possible cryptic species and obligatory parasitism. We also report new records from the eastern Adriatic Sea, helping to fill the existing gaps in the known distribution of the morphotype S. savaglia .

The study presents an exceptional number of records of the devil firefish Pterois miles along the Croatian coast. These records are based on 122 confirmed sightings of the species recorded between June 2024 and January 2025, providing evidence of a rapid and extensive expansion of the species in the eastern Adriatic waters. Most records originated from citizen science via direct reports of sightings, complemented by monitoring of social networks and online media platforms. The highest number of sightings was recorded around the islands of Lastovo and Vis, while the area around Dubrovnik had the highest number of sightings along the mainland coast. The majority of individuals (72.7%) were sighted within the first 15 meters of depth, with most individuals estimated to be 15 cm or smaller in length. No correlations between depths and lengths of individuals, as well as between time and latitude of sighting were detected. Most sightings occurred during diving activities, with a few involving captured specimens. The observed expansion is likely a result of larval transport via sea currents and subsequent settlement, as the pattern of records aligns with general circulation patterns along the eastern Adriatic coast. Given the species’ biological traits, which facilitate rapid and extensive establishment in invaded areas, this expansion poses certain ecological risks, particularly in key coastal habitats that host ecologically and economically important fish species. We encourage targeted removal strategies, particularly in ecologically significant areas such as Marine Protected Areas (MPAs), commercialization of the species and reduction of fishing pressure on natural predators as mitigation measures.

In the circalittoral zone of the Mediterranean Sea, the nursehound Scyliorhinus stellaris lays eggs in spawning areas located at depths between 25 and 50 m in the red gorgonian meadows. Given the evident decline of the nursehound population in the Mediterranean and its high vulnerability, investigating spawning and potential nursery areas is crucial for the conservation of this species. Using non-invasive techniques such as diving activities with the help of R.O.V. (Remote Operated Vehicle), spawning areas have been identified along the Tuscany coast in Italy. In addition, B.R.U.V.S. (Baited Remote Underwater Video System) was used as an auxiliary method to diving activities in order to record the presence of nursehound individuals. Between 2018 and 2024 (except for 2022), 66 eggs were spotted around Monte Argentario peninsula on the Argentarola Island, Grotta del Corallo, Cala Grande, Capo D’Uomo, Cala della Maddalena and around Giannutri Island in Punta Scaletta. The highest number of eggs was observed around the Argentarola Island, Grotta del Corallo, and Cala Grande, both daily and during the entire study period, which suggests that these three sites represent spawning areas. Furthermore, two adult nursehound individuals have also been sighted near Argentarola Island, suggesting this site could represent a potential nursery area. Further data will be collected in these sites through more in-depth investigation in order to understand spatial distribution patterns, relative abundance, population estimates and behavior of this species along the Tuscany coast.

Native to the Indo-Pacific region, the sacoglossan species complex Elysia cf. marginata-grandifolia is considered a Lessepsian migrant and an alien species in the Mediterranean Sea, following its first record along the coast of Turkey in 2001, and consecutive observations in the area. Subsequent studies have reported its presence in the Levantine basin along the coasts of Turkey, Israel, Lebanon, and Cyprus, with uncertainties around its taxonomic assignment. This paper highlights the presence of two alien Elysia species included in these reports, separated now for the first time. We also present new findings of Elysia sp. 2’s range, marking its first occurrence in the Aegean Sea in July 2024 along the coast of Lipsi Island, Greece. This record represents the species’ westernmost distribution in the Mediterranean basin, highlighting a potential ongoing range expansion. Although further examinations in the region would be needed to fully ascertain whether an established population is present in the Aegean Sea, this report demonstrates the importance of continuous monitoring in the early detection of the presence of alien and invasive species, to inform conservation and management strategies.

The Atlantic blue crab, Callinectes sapidus Rathbun 1896, is a highly invasive species in the Mediterranean Sea, posing significant ecological and socio-economic threats in marine and estuarine environments. This study investigates the occurrence and potential impacts of C. sapidus in Italian inland waters, specifically examining specimens collected from an irrigation canal in Pomposa on the Adriatic coast and from the Ombrone River, flowing into the Tyrrhenian Sea. Morphometric analysis revealed that males from Pomposa had a mean carapace width (CW) of 172.15 mm (±23.77 mm) and a mean weight of 282.10 g (±98.34 g), while females had a mean CW of 160.68 mm (±25.76 mm) and a mean weight of 173.26 g (±56.11 g). In contrast, males from the Ombrone River were significantly smaller, with a mean CW of 73.36 mm (±10.11 mm) and a mean weight of 25.33 g (±8.86 g). The sex ratio in Pomposa was heavily skewed towards males (3.26:1), suggesting a dominance of adult males in this freshwater habitat. A similar trend was observed in the Ombrone River, though based on a smaller sample size, with only 1 female among 10 specimens. The condition factor (K) was significantly higher for females (1.960) than for males (0.116), while growth coefficient (b) for males had a higher value (2.401) than that of females (1.788), indicating differing growth patterns. This study provides new ecological and biological data on C. sapidus in freshwater systems, underscoring the need for targeted monitoring and management to mitigate the spread and impact of this invasive species in Italian inland waters.

Adriatic Sea is a diverse marine ecosystem that supports a rich biodiversity of polychaete species on soft and hard-bottoms, with 764 recorded species in the latest inventory list. Benthic surveys conducted in 2018 in the hard-bottom infralittoral zone on the east coast of the central Adriatic Sea revealed one previously unreported species for the Adriatic Sea, Syllis kabilica Ben-Eliahu, 1977 (Syllidae), as well as two species reported for the first time in the eastern Adriatic Sea, Syllis tyrrhena (Licher and Kuper, 1998) (Syllidae), and Streblosoma nogueirai Lezzi and Giangrande, 2019 (Terebellidae). Furthermore, one alien species was identified, Lysidice collaris Grube, 1868 (Eunicidae). These findings provide new insights into the distribution and diversity of polychaete fauna in the Adriatic Sea.

The capture of 176 neonate longnose spurdogs Squalus blainville (Risso, 1827), suggests a potential nursery ground in the eastern Marmara Sea (GFCM GSA28). Sampling was performed by means of a scientific bottom trawl hauled at a depth range of 121-126 m on 21 February 2024. Available data show that S. blainville may be captured in demersal fishery within their first year of life. Total length (TL) and total weight (TW) of the examined males ranged from 169 to 279 mm (238.4±20.7 mm) and from 21.4 to 117 g (66.5±19.8 g), respectively. The TL and TW of the examined females ranged from 187 to 292 mm (241.1±25.3 mm) and from 30.1 to 146 g (66.8±29.2 g), respectively. A male neonate (TL=169 mm) examined is believed to be the smallest free-swimming longnose spurdog caught to date. Under current fisheries regulations, S. blainville is a protected shark species in the waters of Türkiye and therefore should be released if caught as bycatch. However, in addition to reducing fishing pressure on the species by prohibiting targeted fishing, area-based conservation actions, which are based on closing areas that are critical for chondrichthyans (e.g., nurseries) to fishing either on a year-round or seasonal basis, should now be included in the conservation plans for S. blainville and other protected species in Turkish waters.

A biometric analysis was performed on a sample of 420 specimens of the blackspot seabream, Pagellus bogaraveo (Brunnich, 1769), from the eastern Adriatic Sea. The total length of all specimens ranged from 9.2 to 47.8 cm (23.70 ± 7.63 cm). Eighteen morphometric and eight meristic characteristics were determined. There were no statistically significant differences between the sexes in the morphometric and meristic characteristics of the blackspot seabream in the Adriatic Sea. Regarding meristic characteristics, there are no significant morphological differences between the blackspot seabream population in the Adriatic Sea and that in other areas of the Mediterranean Sea and the eastern Atlantic Ocean. Relative growth was studied by comparing changes in morphological characteristics with growth in total length and head length. The results indicate the presence of a single population of P. bogaraveo in the Adriatic Sea.

This review first pays tribute to the famous Croatian oceanographer, Mira Zore-Armanda, and her seminal work on the Adriatic water masses in 1963, and emphasises the importance of the densest Mediterranean water mass: North Adriatic Dense Water (NAddW). This water mass is generated through substantial wintertime surface cooling and evaporation over the wide northern Adriatic and is known to (1) influence the Adriatic-Ionian thermohaline circulation, (2) bring oxygen and carbon to the deep Adriatic layers and, (3) more generally, have a substantial impact on the physics and biogeochemistry of the whole Adriatic. Second, the NAddW physics, from preconditioning, through generation and spreading, to accumulation in Adriatic depressions, is reviewed. Then, the temporal evolution of the NAddW properties influenced and connected to (1) basin-wide interannual and decadal variability and (2) trends towards warmer and saltier source characteristic due to ongoing climate change, is discussed. The importance of long-term observations and atmosphere-ocean modelling in event, decadal and climate studies is then presented. Finally, a review of the identified gaps and perspectives for future research is concluding this article.