Search Results (29)

This article documents the first outbreak of aeromoniasis caused by Aeromonas veronii in farmed European seabass (Dicentrarchus labrax) along the Greek Ionian Sea coast. In late spring 2024, commercially sized fish exhibited anorexia, hemorrhages, and ulcers on the skin, accompanied by elevated morbidity and mortality rates. The outbreak spread rapidly across local farms in Sagiada Bay, reaching its peak in late summer, and extending into the Astakos Gulf, southern in the Ionian Sea. The postmortem examination revealed hemorrhages, organomegaly, abscess formation, and granulomatous inflammation. Aeromonas veronii was isolated from all examined individuals in nutrient media and confirmed by biochemical and molecular methods. Whole genome sequencing and phylogenetic analysis demonstrated genetic homogeneity among two strains from two different areas along the Ionian Sea and a close evolutionary relationship with other Aeromonas veronii strains from the Aegean Sea. Although genetically similar, the isolates exhibited differences in phenotypic and biochemical characteristics, indicating regional variability. The present study provides an overview of the pathology, clinical characteristics and progression of aeromoniasis in Ionian Sea aquaculture, highlighting the need for continued monitoring, in-depth genomic and phenotypic assessment, and the design of region-specific preventive strategies, including autogenous vaccines, for effective disease management. Full article

This article explores the impacts of climate change on the rural and natural landscapes in the region of Eastern Macedonia and Thrace, northeastern Greece. The spatial distributions of the bioclimatic de Martonne Index and the phytoclimatic Emberger Index were calculated at a very high resolution (~500 m) for present conditions (1970–2000), two future time periods (2030–2060; 2070–2100), and two greenhouse gas concentration scenarios (RCP4.5; RCP8.5). The results show significant bioclimatic changes, especially in the Rhodope Mountain range and along almost the whole length of the Greek–Bulgarian border, where forests of high ecosystem value are located, together with the rural areas along the Evros river valley, as well as in the coastal zone of the Aegean Sea. The article describes the processes of bioclimatic changes that can significantly modify the study area’s landscapes. The study area reveals a shift toward xerothermic environments over time, with significant bioclimatic changes projected under the extreme RCP8.5 scenario. By 2100, de Martonne projections indicate that around 40% of agricultural areas in the eastern, southern, and western regions will face Mediterranean and semi-humid conditions, requiring supplemental irrigation for sustainability. The Emberger Index predicts that approximately 42% of natural and agricultural landscapes will experience sub-humid conditions with mild or cool winters. In comparison, 5% will face drier humid/sub-humid, warm winter conditions. These foreseen futures propose initial interpretations for key landscape conservation, natural capital, and ecosystem services management. Full article

This study examines sediment distribution patterns in the Aegean Sea, focusing on the western coast of Evia Island and the southern Evoikos and Petalioi Gulfs. A total of 200 granulometric data points were analyzed to evaluate textural characteristics, including mean grain size, sorting, and skewness. The findings reveal significant variation in mean grain size: finer sediments (ϕ = 5–8) dominate the northern Aegean near Skyros, while coarser sands (ϕ = 2–4) are prevalent in the South Evoikos and Petalioi gulfs. The coarsest materials (ϕ = 0–2) are found around Chalkis, with sorting generally poor except in those two areas. Negative skewness values in the northern part of the study area indicate a predominance of finer particles, while southern regions exhibit slightly positive skewness, suggesting a greater proportion of coarser grains. Complex net transport patterns between Evia and Skyros are influenced by north-northeast trending water currents from the northern Aegean, with fluvial influx observed in the southern Evia coastal area. Around Skyros, the interplay of water currents and prevailing north-northwest winds dictates the orientation of net transport vectors. In the Evoikos gulfs, sediment movement aligns with a general northward flow, featuring coarse sediments in the Petalioi Gulf and muddy deposits in the narrower northern segment, where minimal transport indicates stagnant conditions. Coarse-grained materials in North Evoikos are primarily influenced by strong tidal activity. Full article

The summer of 2024 witnessed record-high sea surface temperatures (SST) across the Aegean, Ionian, and Cretan Seas (AICS), following unprecedented air heatwaves over the sea under a long-term warming trend of 0.46 °C/decade for the mean atmospheric temperature (1982–2024). The respective mean SST trend for the same period is even steeper, increasing by 0.59 °C/decade. With mean summer surface waters surpassing 28 °C, particularly in the Ionian Sea, the southern Cretan, and northern Aegean basins, this summer marked the warmest ocean conditions over the past four decades. Despite a relatively lower number of marine heatwaves (MHWs) compared to previous warm years, the duration and cumulative intensity of these events in 2024 were the highest on record, reaching nearly twice the levels seen in 2018, which was the warmest until now. Intense MHWs were recorded, especially in the northern Aegean, with extensive biological consequences to ecosystems like the Thermaikos Gulf, a recognized MHW hotspot. The strong downward atmospheric heat fluxes in the summer of 2024, following an interannual increasing four-decade trend, contributed to the extreme warming of the water masses together with other met-ocean conditions such as lateral exchanges and vertical processes. The high temperatures were not limited to the surface but extended to depths of 50 m in some regions, indicating a deep and widespread warming of the upper ocean. Mechanisms typically mitigating SST rises, such as the Black Sea water (BSW) inflow and coastal upwelling over the eastern Aegean Sea, were weaker in 2024. Cooler water influx from the BSW decreased, as indicated by satellite-derived chlorophyll-a concentrations, while upwelled waters from depths of 40 to 80 m at certain areas showed elevated temperatures, likely limiting their cooling effects on the surface. Prolonged warming of ocean waters in a semi-enclosed basin such as the Mediterranean and its marginal sea sub-basins can have substantial physical, biological, and socioeconomic impacts on the AICS. This research highlights the urgent need for targeted monitoring and mitigation strategies to address the growing impact of MHWs in the region. Full article

This study is focused on one of the most active features of the Hellenic Volcanic Arc Southern Aegean Sea, the Santorini Island Volcanic Complex (SVC). The recent volcano-tectonic crisis in the intracalderic area has emerged the need for closer monitoring of the region. The 2011–2012 unrest has been attributed to the augmentation of fluid flow inside local mapped fracture zones. After March 2012, the seismic activity dropped significantly, raising questions about whether we would have a long period of quiescence or be on a break before the next period of unrest. In this research, a re-examination of the seismic outbreak of 2011–2012 was conducted by adding more travel-time data from 2013 while we further analyzed the waveform data from 2014 to May 2024 to explore the differences of the SVC body-wave velocity structure by performing seismic tomography in these two time windows. The new dataset serves to identify the state of the Santorini Volcanic Complex. The results show a significant reduction in Vp and Vs anomalies at shallow depths since the period of unrest. At the same time, the distribution of Vp/Vs ratio remains high (>1.87) in the area NNE of Kameni at a shallower depth (2 km). The areas of Christiana Islands and Columbo volcano are mainly characterized by negative body-wave anomalies and low Vp/Vs ratio (1.56–1.64) at shallow depths for the study period, while a possible explanation to results in the submarine volcano may be explained by dry steam/gas phases that may have resulted in the generation of the swarms that occurred in the region. Full article

In the Mediterranean, the bluespotted cornetfish Fistularia commersonii Rüppell, 1838, presents a minor socioeconomic impact and the assessment of any environmental impact requires more relevant data. The congeneric red cornetfish Fistularia petimba Lacepède, 1803, has expanded its distribution range within the basin but only small numbers have been reported to date. A total of 207 individuals of F. commersonii were collected between April 2021 and March 2022 from the Levantine coast of Rhodes and 92 more from various locations. Additionally, 13 individuals of Fistularia petimba were caught in March 2024 from the Aegean coasts of the island. We aim to assess the current progression of the population of the two cornetfish, the possible further exploitation of F. commersonii to boost the local fishing economy, their possible dietary overlaps and to add valuable biological and ecological data. In F. commersonii, male to female ratio (1:1.33) significantly departed from 1:1, with length–weight relationships exhibiting positive allometric growth. Six age groups were identified. The highest reproductive intensity was observed during summer. The onset of sexual maturity was estimated at 65.52 cm in total length (1.8 years). Longevity was estimated at 11.1 years with females growing larger than males. The exploitation rate (E = 0.47) indicated that the population is underexploited. The optimum and target fishing mortality were higher in comparison with the present fishing mortality (F = 0.48), indicating a potential for commercial exploitation of the species. For F. petimba, the sex ratio was 1:2.25. The species preys on crustaceans, followed by fish and molluscs. The finding of Vanderhorstia mertensi (Klausewitz, 1974) in the stomach content of both cornetfishes constitutes the second published record for Hellenic waters and the first for the Dodecanese Islands. Full article

Respiratory disorders significantly impact adolescents’ health, often resulting in hospital admissions. Meteorological elements such as wind patterns have emerged as potential contributors to respiratory symptoms. However, it remains uncertain whether fluctuations in wind characteristics over extended periods have a tangible impact on respiratory health, particularly in regions characterized by distinct annual wind patterns. Crete is situated in the central-eastern Mediterranean Sea and frequently faces southerly winds carrying Sahara Desert sand from Africa and northerly winds from the Aegean Sea. This retrospective study analyzes long-term wind direction data and their relationship to respiratory symptoms observed in children up to 14 years old admitted at the University Hospital of Heraklion between 2002 and 2010. Symptoms such as headache, dyspnea, dry cough, dizziness, tachypnea, throat ache, and earache were predominantly reported during the presence of southern winds. Fever, productive cough, and chest pain were more frequently reported during northern winds. Cough was the most common symptom regardless of the wind pattern. Southern winds were significantly associated with higher probabilities of productive or non-productive cough, headache, dyspnea, tachypnea, dizziness, earache, and throat ache. Northern winds were related to a higher incidence of productive cough. Rhinitis, asthma, allergies, pharyngitis, and sinusitis were related to southern winds, while bronchiolitis and pneumonia were associated with northern winds. These findings underscore the critical role of local climatic factors, emphasizing their potential impact on exacerbating respiratory conditions in children. Moreover, they point out the need for further research to elucidate the underlying mechanisms and develop targeted interventions for at-risk populations. Full article

This paper presents the results of an analysis of stranding events of the Mediterranean monk seal Monachus monachus over a decade. The analysis involved categorization according to the cause of stranding and seasonality, the identification of hotspot stranding areas and an assessment of possible correlations between stranding events and environmental/climatic patterns using time series analysis. Moreover, Generalized Additive Models (GAMs) were applied to explore the effects of the size of small-scale fishing grounds, the number of species sightings, and the occurrence of reproduction sites on “human-related” strandings. Finally, special focus was put on the central part of the eastern Ionian Sea for the assessment of stranding hotspot areas by means of the Multi-Criteria Decision Analysis (MCDA) approach, based on different kinds of spatial information such as anthropogenic pressures and the location of breeding sites and feeding grounds. Time series analysis results revealed that oscillation indices, during the first half of the year, and sea surface temperature (SST) in the Mediterranean from October to December were positively correlated with monk seal stranding events. GAMs underlined that areas combining extended small-scale fishery grounds and a higher number of sightings were more likely to cause more strandings. Regarding spatial analyses, the central Aegean Sea was highlighted as a hotspot for “human-related strandings”, while the MCDA approach emphasized that the southern coasts of Cephalonia and the gulf between Lefkada and mainland Greece were susceptible to subadult strandings. Full article

The devil firefish Pterois miles (Bennett 1828) is recognized as one of the 100 worst invasive alien species (IAS) in the Mediterranean Sea with significant socioeconomic and ecological implications. A total of 363 individuals were collected between April 2021 and March 2022 from the Levantine Sea (the Eastern Mediterranean), aiming to assess the current progression of the population. The male to female ratio (1:1.03) did not significantly depart from 1:1, with length–weight relationships exhibiting positive allometric growth. Five age groups were identified, with the third and fourth age groups being the predominant (74% of the population). The highest reproductive intensity was observed during summer followed by autumn. The onset of sexual maturity (L₅₀) for the total population was estimated at 22.44 cm in total length (2.1 years). The asymptotic length was estimated at 45.35 cm for the total population, with males growing larger than females. Longevity was estimated at 14.4 years for the total population. The inflection point was estimated at 4.31 years for the total population. Length with a 50% probability of capture (LC₅₀) was estimated at 23.03 cm, with the respective age (t₅₀) of 2.2 years. The exploitation rate (E = 0.48) indicated that the population is underexploited. The optimum (F_opt) and target (F_lim) fishing mortality were higher in comparison with the present fishing mortality (F = 0.41), indicating a potential for commercial exploitation of the species. Full article

The evolution and drivers of dense water formation (DWF) in the North–Central Aegean Sea (NCAeg) during winter 2021–2022 are studied using observations from two Argo floats and the output of an operational data-assimilating model. Dense water with ${\sigma }_{\theta }>29.1 {\mathrm{kg}\mathrm{m}}^{-3}$ was produced over most of the NCAeg, except for the northeastern part covered by Black Sea water (BSW), where the maximum surface density was $<29 {\mathrm{kg}\mathrm{m}}^{-3}$. The highest density waters were produced over the central and southern parts of the Lemnos Plateau and in the shallow coastal areas between Chios Island and the Edremit Gulf. Atmospherically driven transformation to the east of Lesvos Island resulted in the production of waters with anomalously high density and salinity, which flowed inside Skiros Basin, thus partly explaining its historically higher density and salinity compared to the rest of the NCAeg subbasins. The Skiros and Athos Basins were ventilated down to ${\sigma }_{\theta }$∼$29.35 {\mathrm{kg}\mathrm{m}}^{-3}$ horizons. The $29.1 {\mathrm{kg}\mathrm{m}}^{-3}$ isopycnal rose by ∼$200 \mathrm{m}$, and the $29.25 {\mathrm{kg}\mathrm{m}}^{-3}$ isopycnal overflowed above the ∼$400 \mathrm{m}$ sill depth filling the southern depressions of the NCAeg. Combining data from Argo floats, vessel casts, gliders, and a fixed-point observatory, the dense water produced in the NCAeg was observed spreading in the deep layer of the Central Cretan Sea for at least one and a half years after the formation. The cyclonic circulation of the newly formed water in the NCAeg has been observed directly for the first time using deep-drifting floats. The Eastern Mediterranean warming and salinification signal has propagated below the NCAeg sill depth. The winter average buoyancy loss was comparable to that of the peak of the Eastern Mediterranean transient (EMT) and other known years of DWF in the NCAeg; however, the high temperature of the upper layers due to long-term warming prevented the widespread formation of denser water. Full article

This study delves into the southern Aegean regionwhere the subduction of the oceanic Mediterranean lithosphere under the Aegean continental one takes place. This region is considered one of the most active ones in the eastern Mediterranean Sea due to intense tectonic movements in the Late Quaternary. More than 1200 manually revised events from 2018 to 2023 have been used in order to obtain the 3D structure of body-wave velocity and V_P/V_S ratioto 80 km depth through earthquaketomography. A series of resolution tests have been performed and demonstrated fair resolution of the derived velocity structures in the area of interest. The derived anomalies of body-waves (dV_P, dV_S) and V_P/V_S ratio provided important information about the southern Aegean regional tectonics and secondarily active faults of smaller scale (>20 km). The region is marked by significant low-velocity anomalies in the crust and uppermost mantle, beneath the active arc volcanoes. The seismicity related to the Hellenic Subduction Zone (HSZ) is connected to a low-angle positive anomaly of V_P and V_S, correlated withthe observed intermediate-depth seismicity (H ≥ 40 km) in this part of the study area. This result could be related to the diving HSZ slab. Full article

The predominant climatological wind regime in summer over the Greek Seas and especially over the Aegean Sea is undoubtedly the Etesian winds system, very well known since the time of the ancient Greeks, who first identified and described its main characteristics. The Etesian winds have been under continuous and intensive research since early 1900s, and numerous papers have been published, which have revealed all the secrets associated with the physical mechanisms responsible for their creation and maintenance. The ordinary synoptic situation, which is closely associated with the appearance of spells of Etesian winds outbreaks over the Aegean Sea, refers to cases in which the Subtropical Jet Stream (SJS) is situated over the Greek mainland. Then the frontal surfaces associated with the Polar Jet Stream (PJS), or a polar jet streak, passing through Greece from the north can cause severe weather in northern Greece as far south as Larisa (39.39° N, 22.26° E). Precipitation does not usually occur south of Larisa, because the SJS constitutes a barrier to the southward extension of the upper half of the frontal surface. In this case, cold advection occurs in the lower troposphere, resulting in a drop in temperatures even in southern Greece, due to the establishment of an Etesian winds outbreak. Thereafter, these north-easterly winds persist for a long time, weakening gradually, following the variation of the pressure gradient due to the combination of the mobile dynamic anticyclone positioned over the Balkans, after the passage of the cold front and the permanent Cyprus surface low. The main goal of this article is to investigate how much the case of a time period around 9 July 2022 differs from the conceptual model mentioned above, as deep convection occurred over all of Greece over three successive days, breaking the Etesian winds regime and defeating the low tropospheric stability usually accompanying this wind regime. Full article

Transient Luminous Events (TLEs) are rare electrical discharges occurring in the middle and upper atmosphere above thunderstorms. The results of systematic observations of TLEs in a region that includes Greece and its surrounding area during a 2-year period (September 2020–September 2022) are presented. This study provides a first insight about the frequency, the spatiotemporal distribution, and the variety of these events in that region. In total, 1632 TLEs were observed during these 2 years. Of these, 95.5% were red sprites. Most events occurred over the Ionian Sea, the southern Adriatic Sea, and western Greece. The most favorable period for TLEs in Greece and its surrounding area is from October to February. Noteworthy were two prolific nights, 15–16 October 2020 and 4–5 December 2021, over mesoscale convective systems at the Ionian Sea and the southeastern Aegean Sea, respectively, when hundreds of these events were observed. Observations of this kind are of great significance, not only because they are the first-ever conducted in the aforementioned region but also due to the fact that these events seem to exhibit a relatively high frequency of appearance there. Full article

The current work focuses on establishing the parameters that influence the wind’s behavior over the Aegean and Ionian Seas and estimating the wind potential in the region based on long-term historic climate data. Combining a downscaling technique performed with the well-founded WRF-ARW computational algorithm and a number of simultaneous meteorological station time series, an attempt is made to investigate how regional changes may affect low-altitude wind speed distribution at hub height (100 m a.s.l.). The provided time-series coastal data span the entire region of interest from north to south. WRF-ARW v.3.9 is utilized to associate the geostrophic wind distribution obtained from long-term Copernicus ERA5 wind data with the localized wind potential over lower altitudes. Evaluation and correlation of the observational data to the predicted wind climate are performed, and the statistical differences that arise are investigated. High-accuracy wind resource potential maps are thus obtained in the region. Also, a few distinctive flow patterns are identified, such as wind speed cut-off regions and very high wind speed distributions, which are presented in specific southern regions of the Aegean Sea. Full article

The diet of the lionfish (Pterois miles), an invasive species in the Aegean Sea, was examined by collecting stomach content data from fish collected in three study sites in the Aegean Sea (southern Crete, Kastellorizo, and Nysiros islands). Prey composition in terms of numerical abundance and frequency of occurrence was used to compare lionfish’s diet between these sites. Lionfish largely preyed upon teleosts (4% to 83% numerical abundance and 16% to 58% frequency of occurrence, depending on the site) and decapods (12% to 95% numerical abundance and 11% to 81% frequency of occurrence). The most important teleost families in lionfish’s diet were Gobiidae, Labridae, and Scorpaenidae, while decapods and especially the family Scyllaridae and the genus Plesionika were the dominant decapod prey items. The lionfish was found to be an especially successful generalist across the study sites, an opportunistic, predatory species overall, and at the same time, at a local level, it seems to be an equally successful specialist that could increase the predation mortality of already stressed prey populations and can be a serious threat to endemic, critically endangered, and/or commercially important species. Full article