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The food and feeding habits of the Mediterranean moray eel,Muraena helena, collected in the southern Adriatic Sea by bottom longline fishing, were examined. Of the total 146 specimens, 37 had almost or totally empty stomachs.Muraena helenais a carnivorous species whose diet primarily includes benthic fishes and crustaceans. The diet consisted of at least 27 different prey taxa belonging to 8 major groups. The dietary preferences among the sexes and seasons did not differ statistically, but diet depended on age and reflected differences in prey availability. Also, diet composition significantly differed according to depth, with the cephalopodOctopus vulgarisoccurring in the diet of morays caught just below 30 m, while crustaceans were more common in the diet of specimens sampled in shallower waters. Results indicated thatM. helenais an opportunistic species that feeds on motile prey. Furthermore, a continuing study with a well-designed sample collection is needed to accurately assess the trophic status and the predatory impact ofM. helenawithin the Mediterranean coastal communities. [ABSTRACT FROM PUBLISHER]

The objective of this study was to compare circulating blood cell counts and morphology of three eel species: Muraena helena (moray), Conger conger (European conger) and Anguilla anguilla (Euro-pean common eel). Moray and conger were collected from the Adriatic Sea at the Elaphite Islands near Dubrovnik, Croatia; common eels were collected in the Neretva River, Croatia. Hematological comparison was conducted using Natt-Harrick's and May-Griinwald Giemsa staining methods. The hematocrit of moray and conger were similar, while common eel had higher values by 60%. Manual cell count showed that common eel had the highest erythrocyte count. Conger had a higher erythrocyte count than moray, with a higher percentage of proerythrocytes and senescent erythrocytes compared to moray and common eel. The leukocyte count was similar in common eel and moray and slightly lower in conger. The thrombocyte count was highest in conger and lowest in moray. In all three species, the neutrophil (heterophil) nuclei appeared as either circular or bi-lobed. Moray had the high-est neutrophil (heterophil) percentage and a subtype with intensively basophilic cytoplasm appearing in a similar percentage as the normal type. In common eel, neutrophils (heterophils) were the only detected granulocytes. Basophils were detected in conger eels. Eosinophils were not detected in any of the sampled fish. The size of all cell types in moray was slightly larger than in other two species. In conclusion, our findings reveal major differences in the cell count and diversity in cell subtypes between three kin species of eels. [ABSTRACT FROM AUTHOR]

This study determined basic biological data for the European conger eel Conger conger (L.) population in the coastal waters of the eastern Adriatic Sea. Juveniles and immature females dominated the coastal population, whereas males were relatively uncommon. The population structure determined by the study suggested spatial separation of sexes and spawning grounds in deeper waters. Both edge-type and marginal increment analyses confirmed the formation of a single growth annulus per year on the ground otoliths. The observed maximum age of the coastal conger eels was 8 years, although most of the sampled fish were 5 years old. The estimated parameters of the von Bertalanffy growth model suggested that the growth of the conger eels was relatively slow. C. conger is an opportunistic predator. Its diet was composed primarily of fishes, followed by crustaceans and cephalopods. Due to the evident site fidelity of the species, the wide prey spectrum of the conger eels (33 taxa) reflected the local benthic community structure. [ABSTRACT FROM AUTHOR]

The article focuses on the northernmost record of the shameafced crab calappa granulata in the Mediterranean area. On December 4, 2010, a specimen of the shamefaced crab Calappa granulata was collected in the Northern Adriatic northwest off Umag, Croatia on the western coast of the Istria Peninsula.

The article features the endemic cyprinid fish specie Chondrostoma knerii Heckel also known as Podustva in Croatia and Bosnia & Herzegovina. It presents the conservation status, taxonomy, distribution, abundance, habitat and ecology, conservation actions done toward the fish specie. Meanwhile, the fish is noted to be endangered in Croatia due to the hydrological changes of the environmental quality in Neretva River and the presence of the pest species Lepomis gibbosus and Gymnocephalus cernuus.

The article offers information on Salmo dentex, tooth trout. Salmon fish is identified to have a laterally compressed body, back with sliverish color fading gradually to white in the abdomen, pointed head, narrow snout and greyish fins that turning in orange during the spawning season. Salmo dentex is declared to be a vulnerable and critically endangered which is locally inhabiting in the main rivers of the Adriatic watershed in Croatia, Bosnia-Herzegovina and Montenegro. Recommendations for conservation of the tooth trout, includes an effective habitat protection, specially of spawning areas and water quality enhancement and a detailed study of current population status, biology and ecology.

The Adriatic Sea and Adriatic Sea drainage system (or Adriatic region) is characterized by high levels of species richness. This especially applies to endemic fishes, as exemplified by the sand gobies. However, the diversity of this group is probably still underestimated. Several keys for gobiid identification, notably of the Adriatic region, have been proposed on the basis of morphological characters, but difficulties persist in species identification. Molecular phylogenies support the monophyly of the sand gobies, but relationships between genera and species remain poorly resolved. In this work, the diversity and evolutionary history of the Adriatic sand gobies (Pomatoschistus and Knipowitschia) were investigated by applying phylogenetic reconstructions, species delimitation tests, and molecular dating based on mitochondrial cytochrome b and nuclear rhodopsin 1 genes. The concatenation of both genes allowed, for the first time, the creation of a highly resolved phylogeny at the interspecific level. The generic diversity within the sand gobies is probably considerably higher than formerly assumed. Our results highlight cryptic diversity and suggest that new species remain to be described within Knipowitschia and Pomatoschistus. Most of all, our results emphasized the urgent need of a taxonomic revision of the sand gobies. Several past events were at the origin of sand goby diversification in the Adriatic region. It seems that glacial periods promoted the intraspecific diversification of the endemic species, whereas interglacial periods promoted the (re)colonization of the Adriatic Sea by more widespread species. [ABSTRACT FROM AUTHOR]

Fish of the genus Squalius inhabit various freshwater habitats across Europe and Asia, with a particularly high diversity in the Mediterranean area, but the taxonomic status of many populations is still a matter of debate. This study aims to resolve the taxonomic uncertainties of chubs distributed in the Adriatic basin of Croatia and Bosnia and Herzegovina. Phylogenetic reconstruction based on the mitochondrial gene for cytochrome b and two nuclear genes, the recombination activating gene 1 and the rhodopsin gene, reveal high diversity of chubs in the investigated area. Two evolutionary independent groups are revealed: the first comprising the species Squalius illyricus , S. microlepis , S. svallize , S. tenellus and S. zrmanjae , and a second group corresponding with S. squalus. Genetic distinctiveness of species belonging to different groups is high due to their divergence that began in the Middle Miocene. In addition to allopatric speciation as the main force of divergence of Adriatic Squalius species, several instances of natural hybridizations were detected, contributing to the observed diversity. A comparison of phylogenetic scenarios using Bayesian factors corroborated the molecular basis for recognition of six Squalius species in the Adriatic basin, while Squalius janae is confirmed to be a junior synonym of S. squalus. [ABSTRACT FROM AUTHOR]

Abstract Differential tectonic activity is a key factor responsible for variable relative sea-level (RSL) changes during the late Holocene in the Adriatic. Here, we compare reconstructions of RSL from the central-eastern Adriatic coast of Croatia with ICE-7G_NA (VM7) glacial-isostatic model RSL predictions to assess underlying driving mechanisms of RSL change during the past ∼ 2700 years. Local standardized published sea-level index points (n = 23) were combined with a new salt-marsh RSL reconstruction and tide-gauge measurements. We enumerated fossil foraminifera from a short salt-marsh sediment core constrained vertically by modern foraminiferal distributions, and temporally by radiometric analyses providing sub-century resolution within a Bayesian age-depth framework. We modelled changes in RSL using an Errors-In-Variables Integrated Gaussian Process (EIV-IGP) model with full consideration of the available uncertainty. Previously established index points show RSL rising from −1.48 m at 715 BCE to −1.05 m by 100 CE at 0.52 mm/yr (−0.82-1.87 mm/yr). Between 500 and 1000 CE RSL was −0.7 m below present rising to −0.25 m at 1700 CE. RSL rise decreased to a minimum rate of 0.13 mm/yr (−0.37-0.64 mm/yr) at ∼1450 CE. The salt-marsh reconstruction shows RSL rose ∼0.28 m since the early 18th century at an average rate of 0.95 mm/yr. Magnitudes and rates of RSL change during the twentieth century are concurrent with long-term tide-gauge measurements, with a rise of ∼1.1 mm/yr. Predictions of RSL from the ICE-7G_NA (VM7) glacial-isostatic model (−0.25 m at 715 BCE) are consistently higher than the reconstruction (−1.48 m at 715 BCE) during the Late Holocene suggesting a subsidence rate of 0.45 ± 0.6 mm/yr. The new salt-marsh reconstruction and regional index points coupled with glacial-isostatic and statistical models estimate the magnitude and rate of RSL change and subsidence caused by the Adriatic tectonic framework. Highlights • Reconstruction of relative sea-level change over past 2700 years shows 1.48 m rise. • Lower magnitudes predicted from ICE-7G_NA (VM7) glacial isostatic model. • Offset related to tectonic subsidence at a rate of 0.45 mm/yr. • New salt-marsh reconstruction shows 0.28 m rise since early eighteenth century. • Relative sea-level rate shows gradual rise towards the present at 1.1 mm/yr. [ABSTRACT FROM AUTHOR]

Small-scale fisheries (SSF) in Croatia and Montenegro have a long tradition, similar to those of SSFs in other parts of the coastal Mediterranean. In order to improve fisheries management and save the cultural heritage of fishing traditions on the eastern Adriatic coast, scientists and fisheries managers, from these two countries, made an effort, to gain a better understanding of fishing activities and targeted stocks. This is a complex research topic, due to the high and increasing fishing pressure on marine resources as well as the fact that fisheries management throughout the Mediterranean region remains conventional in its nature. Basic characteristics of SSFs in each country are presented. Specific conclusions related to improvement of coastal resources state in term of sustainable use are suggested together with proposal for additional conservation measures and actively involving fishermen in the management process. Finally, guidelines for future management in terms of monitoring and data collection framework (DCF) are proposed for both countries. [ABSTRACT FROM AUTHOR]

Artisanal fisheries in Croatia and throughout the Mediterranean coastal region have a long tradition. In recent times the booming growth of human populations along Mediterranean coasts has led to harvesting of its marine resources in almost insupportable quantities, thus placing the research of this topic in a complex context. At the same time, fisheries management throughout the Mediterranean region has remained conventional in its nature, implying that it is almost only based on gear specific management provisions. The current Croatian legislative framework and legislative changes of artisanal fisheries regulation in the last 15 years, as well as how these changes have impacted on the state of coastal fish resources, particularly target species condition, are discussed. The conclusion is that if we want to improve further the state of the resources a more comprehensive set of management measures incorporating closed areas and a new approach actively involving fishers in the management process should be adopted. Finally, guidelines for future management in terms of the monitoring and data collection framework (DCF) proposed by the EU are demonstrated. [ABSTRACT FROM AUTHOR]

A multivariate analysis of juvenile fish community data, sampled at two nursery sites at an interval of 17 years (2000—early, and 2017—late), was conducted to elucidate the trends of change in littoral juvenile fish communities along the eastern Adriatic coast. Fishing, trophic and taxonomic composition to the community data were analysed for possible causality. The ichthyofaunal composition differed significantly for Site, Period and all interactions. According to the mMDS ordination plot, four groups of communities were defined, with clear cyclicity. No patterns were found in species composition between sites in the early period, while the observed community changes were governed by the same pattern at both sites in the late period. The species that contributed most to the observed changes were non-commercial, small, benthic resident fishes, such as gobiids and blennids, or those associated with canopy alga for shelter and feeding. The analysis correctly allocated samples based on community information to Sites and Periods. The data obtained provided an invaluable opportunity to test for the generality of potential patterns of change in littoral fish communities, suggesting that significantly modified juvenile fish communities may be the result of constant human embankment and marine infrastructure construction along the coast in recent decades, rather than climate change or fishing pressure, as generally considered. [ABSTRACT FROM AUTHOR]

Le 10 octobre 2016, un spécimen de Micropterus salmoides a été capturé au trémail dans la rivière Neretva (système de drainage adriatique de Croatie). C'est le premier signalement de l'achigan à grande bouche dans cette rivière, et par conséquent dans le système hydrographique drainé vers l'Adriatique. [ABSTRACT FROM AUTHOR]

The issue of plastic pollution has dramatically intensified in the recent years. Our study investigates extensive plastic contamination of a sandy beach on a small Adriatic island. The beach was sampled on three occasions, in 2013, 2020 and 2022, using 1 m 2 quadrats placed along the lower and upper strandlines, resulting in average litter concentrations of 385 ± 106, 1095 ± 522 and 129 ± 37 item m -2 , respectively. The lower size limit of collected litter was 1 mm, thus including large microplastics. Plastic fragments (49-74 %) and plastic pellets (15 %-37 %) were predominant litter categories. The proportion of fragments is significantly higher during the tourist season with a more intensive cleaning regime (April-October), as opposed to the off-season (November-March). Fisheries and aquaculture litter was identified as a relevant source of pollution. More research is needed in the future into the microplastics smaller than 1 mm., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Pero Tutman reports financial support was provided by Croatian Ministry of Science and Education. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Globally, marine bioinvasions threaten marine ecosystem structure and function, with the Mediterranean Sea being one of the most affected regions. Such invasions are expected to increase due to climate change. We conducted a risk screening of marine organisms (37 fishes, 38 invertebrates, and 9 plants), both extant and 'horizon' (i.e., not present in the area but likely to enter it). Based on expert knowledge for the Eastern Adriatic Sea coasts of Slovenia, Croatia, and Montenegro, screenings were conducted under both current and predicted climate conditions indicating with an increase in sea surface temperature and salinity of the Adriatic Sea together with changes in precipitation regime. Our aims were to: (1) identify non-native extant and horizon marine species that may pose threats to native biodiversity and (2) evaluate the risk of invasiveness of the selected species under current and predicted climate conditions. Of the 84 species screened, there was an increase in those ranked as 'high risk' from 33 (39.3%) under current climate conditions and to 47 (56.0%) under global warming scenarios. For those ranked as 'very high' risk, the increase was from 6 (7.1%) to 21 (25.0%). Amongst the screened species, the already established high-risk species Pacific oyster Magallana gigas and Atlantic blue crab Callinectes sapidus represent a threat to ecosystem services. Given the under-representation of marine species in the current European Union List, the species we have ranked as high to very high risk should be included., Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-023-00196-9., Competing Interests: Conflict of interestThe authors declare no competing interests. The authors alone are responsible for the content and writing of the article., (© Ocean University of China 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment areas across all six inhabited continents screened 819 non-native species from 15 groups of aquatic organisms (freshwater, brackish, marine plants and animals) using the Aquatic Species Invasiveness Screening Kit. This multi-lingual decision-support tool for the risk screening of aquatic organisms provides assessors with risk scores for a species under current and future climate change conditions that, following a statistically based calibration, permits the accurate classification of species into high-, medium- and low-risk categories under current and predicted climate conditions. The 1730 screenings undertaken encompassed wide geographical areas (regions, political entities, parts thereof, water bodies, river basins, lake drainage basins, and marine regions), which permitted thresholds to be identified for almost all aquatic organismal groups screened as well as for tropical, temperate and continental climate classes, and for tropical and temperate marine ecoregions. In total, 33 species were identified as posing a 'very high risk' of being or becoming invasive, and the scores of several of these species under current climate increased under future climate conditions, primarily due to their wide thermal tolerances. The risk thresholds determined for taxonomic groups and climate zones provide a basis against which area-specific or climate-based calibrated thresholds may be interpreted. In turn, the risk rankings help decision-makers identify which species require an immediate 'rapid' management action (e.g. eradication, control) to avoid or mitigate adverse impacts, which require a full risk assessment, and which are to be restricted or banned with regard to importation and/or sale as ornamental or aquarium/fishery enhancement., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Shallow seafloor marine litter (ML) is the least studied component of ML, and a better understanding of its distribution and accumulation patterns is needed to develop efficient management practices. Abundance and composition of seafloor ML were quantified in two eastern Adriatic Natura 2000 sites (Vis Island and Pakleni Islands), applying a structured sampling design to test whether the intensity of nautical tourism or exposure to prevailing winds and currents are significant drivers determining the ML distribution on shallow, coastal seafloor. ML was widespread and present in considerable amounts across the entire studied area, regardless of the remoteness from most known potential ML sources. Tourism intensity and exposure seem not to be significant predictors of ML accumulation in the investigated Natura 2000 sites. ML abundances displayed large small-scale spatial variation, while for ML composition at a larger scale, regional differences between the two Natura 2000 sites were detected. The Pakleni Islands are mainly polluted by glass items, suggesting a local vessel-based source. The ML composition on Vis Island, with a predominance of plastics, is more determined by long-distance transport. The study indicates the complexity and multi-layeredness of processes driving the patterns of seafloor ML accumulation. Hence, it is suggested to mitigate the issue by addressing the root causes: inadequate waste management and lack of public awareness., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Marine litter is a threat to marine life and an economic burden for coastal communities, but efforts to address the issue are hampered by the lack of data for many countries. We performed the first harmonized assessment of seafloor litter (trawl and visual surveys) in six countries of the Adriatic-Ionian macroregion. Seafloor litter showed an uneven distribution throughout the area, with large differences in litter densities and composition among countries and locations. An emerging problem in the area resulted in short-term & single-use objects that represented the largest fraction of litter. Packaging was the economic sector contributing most to seafloor litter on the continental shelf and upper slope, while in some areas aquaculture (mussel farming) represented a key activity producing marine litter. In coastal areas and bays (e.g. Boka Kotorska bay, Montenegro), seafloor litter was mainly related to construction activities and electronic goods, which are a consequence of fly-tipping/illegal dumping., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The aim of this study was to determine the levels of trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in plastic pellets collected from two sandy beaches on the island of Vis, Croatia. A total of 92 pellets in a sediment volume of 3965 mL were collected at the investigated sampling sites. Concentrations of pellets in sediment samples ranged from 6 to 36 particles dm -3 of wet sediment. Mean particle weight of the collected beached pellets ranged from 17 mg to 31 mg. Trace metal concentrations in plastic pellets were greater than the concentrations reported for seawater in the investigated area, which indicates that plastic pellets sorb metals from the marine environment. The adsorbed trace metals may enter the food chain due to incidental ingestion of microplastic particles by marine animals, which presents a potential human health risk due to consumption of seafood., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This study presents data on the marine litter occurrence in the stomachs of fish species living in different marine habitats for the Adriatic and NE Ionian Sea macro-region. "Macro-litter" was examined in 614 specimens belonging to 11 species, while micro-litter in 230 specimens belonging to 7 species. The study highlights for the first time the presence of litter in the stomachs of the fish species Citharus linguatula. The occurrence of "macro-litter" in the guts of fish was <3% in both the NE Ionian and N Adriatic but reached 26% in the S Adriatic Sea. Micro-litter occurrence was 40 for the NE Ionian and increased to 87% in the N Adriatic (Slovenian Sea). The ingested "macro" and micro-litter differed among the areas. The marine habitat was found to affect the "macro"-litter ingestion but not the micro-litter., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The abundance, composition and sources of marine litter were determined on beaches located in the seven countries of the Adriatic-Ionian macroregion, namely Albania, Bosnia and Herzegovina, Croatia, Greece, Italy, Montenegro and Slovenia. A total of 70,581 marine litter items were classified and recorded through one-year long surveys carried out in 31 sites. The average litter density of 0.67 items/m 2 found within this study is considered to be relatively high. The beaches investigated differed in terms of human-induced pressures; their majority is classified either as semi-urban or semi-rural, while very few beaches could be characterized as urban or remote/natural. The majority of litter items were made of artificial/anthropogenic polymer materials accounting for 91.1% of all litter. Litter from shoreline sources accounted for 33.4% of all litter collected. The amount of litter from sea-based sources ranged in the different countries from 1.54% to 14.84%, with an average of 6.30% at regional level., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Lampetra soljani, new species, is described from the lower Neretva River in the Adriatic Sea basin. Previously it was identified as L. zanandreai. Based on morphological similarity and mitochondrial genetic data, it is related to L. lanceolata and L. ninae from the Black Sea basin. Lampetra soljani is distinguished from all other species of Lampetra by having a marmorate flank pattern in live, fully grown ammocoetes, and in some adults (vs. plain colour pattern). Lampetra soljani is distinguished from other Lampetra species by having three velar tentacles, 54-57 trunk myomeres between the last branchial opening and the anus, no posterial teeth and a bicuspid middle endolateral tooth. Lampetra soljani is also well distinguished by COI barcode data from its congeners. The new species is widespread in the Neretva River drainage and lampreys from Lake Skadar basin are likely to belong to this species also.