Transitional Waters Research Articles

Characterization of Synanthropic Habitats on Shallow Seabeds Using Map Clustering Techniques: A Case Study in Taranto, Apulia, Italy

The Mar Piccolo is a transitional water system located in Taranto city (Southern Italy); it is a semi-enclosed basin affected by severe pollution issues due to the presence of various industrial, agricultural and other anthropic activities that require careful monitoring and management. The pollution levels reached over time have harmed marine biodiversity and human health, repeatedly requiring timely actions for its mitigation. Characterization methodologies and techniques today play a fundamental role in supporting the decision-making phase, processing large quantities of data and identifying complex patterns and correlations. An approach focused on gaining detailed knowledge of complex environmental contexts through clustering map techniques enables highly precise results, capturing even the smallest variations in the features of the study object and strongly correlating them with possible sources of pollution. The use of these techniques improves the precision of the analyses and can significantly contribute to improving the understanding of the environmental state in the Mar Piccolo area. This study addresses the issue of pollution in Mar Piccolo due to marine litter, which has led to the formation of synanthropic habitats on the seabed. It also highlights the value of clustering maps and other characterization techniques for achieving detailed insights at various levels of analysis. Data processing through the proposed methodology can generate very detailed mapping useful for planning precision reclamation interventions that also include species conservation actions, as well as a better understanding of how synanthropic habitats are distributed and evolve. In summary, this study demonstrates how it is possible to improve the precision of data processing, providing crucial details for the management and conservation of highly threatened marine ecosystems.

Assessment of the Trophic Status and Trend Using the Transitional Water Eutrophication Assessment Method: A Case Study from Venice Lagoon

The Transitional Water Eutrophication Assessment Method (TWEAM) is a multi-index set up for assessing the eutrophication risk and trend in transitional waters. It includes a selection of environmental variables, an ecological status indicator (i.e., Macrophyte Quality Index, MaQI) and the Transitional Water Quality Index (TWQI). Possible outcomes of the TWEAM include three trophic classes in terms of eutrophication risk: (i) eutrophic; (ii) non-eutrophic; (iii) mesotrophic. The method was applied on data collected at 28 stations in the Venice Lagoon over four triennial monitoring cycles (MC I-IV) in the period 2011–2022. The spatial variability and medium-term trend of eutrophication risk were investigated, highlighting a general improvement in trophic conditions over time, with a decrease in mesotrophic stations (representing 46% of total in MC-I and 25% in MC-IV) in favor of non-eutrophic stations (46% of total in MC-I and 73% in MC-IV). The main driver of observed positive changes is related to the colonization of sensitive macroalgae and aquatic angiosperms, resulting in an increase in the percentage of stations with MaQI in good/high ecological status from 25% in MC-I to 54% in MC-IV. Eutrophic sites showed a non-linear trend, particularly in choked areas of the central lagoon, with anthropogenic disturbances and low water renewal.

Recent Findings on the Pollution Levels in the Romanian Black Sea Ecosystem: Implications for Achieving Good Environmental Status (GES) Under the Marine Strategy Framework Directive (Directive 2008/56/EC)

This study provides a comprehensive evaluation of contamination levels in the Romanian Black Sea within the framework of the Marine Strategy Framework Directive (MSFD). Over the course of five oceanographic expeditions between 2020 and 2022, data were gathered from 70 stations in transitional, coastal, shelf, and offshore waters of the Black Sea. Analyses were conducted on water, sediment, and biota samples for key contaminants: heavy metals (HMs), polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) such as organochlorinated pesticides (OCPs) and polychlorinated biphenyls (PCBs). The assessment identified contamination hotspots near riverine inputs, urban runoff, harbor activities, and industrial discharges. Offshore waters also showed measurable pollutant levels, likely from diffuse sources and atmospheric deposition. The key findings reveal the widespread contamination of HMs, PAHs, and POPs across the Romanian Black Sea, with concentrations in certain areas exceeding acceptable environmental thresholds, highlighting ongoing challenges for regional pollution management. PAHs were prevalent in both nearshore and offshore regions, while OCPs and PCBs were detected across various matrices, with significant concentrations observed in water and biota samples. The study emphasizes the importance of integrated assessments within the MSFD framework, suggesting that future evaluations should complement the “one out-all out” (OOAO) approach with multi-metric tools, to enhance the robustness of pollution status reporting. Despite improvements in some areas, contamination remains a critical challenge, requiring strengthened regulations, improved waste management, and increased regional cooperation to mitigate the ongoing risks to marine ecosystems. The findings provide valuable data for the upcoming national MSFD assessment cycle (2018–2023) and highlight the need for sustained monitoring and coordinated efforts to ensure long-term marine sustainability.

Microbiome and Resistome Studies of the Lithuanian Baltic Sea Coast and the Curonian Lagoon Waters and Sediments.

the widespread use of antibiotics in human and veterinary medicine has contributed to the global challenge of antimicrobial resistance, posing significant environmental and public health risks. this study aimed to examine the microbiome and resistome dynamics across a salinity gradient, analyzing water and sediment samples from the Baltic Sea coast and the Curonian Lagoon between 2017 and 2023. the composition of the water and sediment bacterial community was determined by Full-Length Amplicon Metagenomics Sequencing, while ARG detection and quantification were performed using the SmartChipTM Real-Time PCR system. the observed differences in bacterial community composition between the Baltic Sea coast and the Curonian Lagoon were driven by variations in salinity and chlorophyll a (chl a) concentration. The genera associated with infectious potential were observed in higher abundances in sediment than in water samples. Over 300 genes encoding antibiotic resistance (ARGs), such as aminoglycosides, beta-lactams, and multidrug resistance genes, were identified. Of particular interest were those ARGs that have previously been detected in pathogens and those currently classified as a potential future threat. Furthermore, our findings reveal a higher abundance and a distinct profile of ARGs in sediment samples from the lagoon compared to water. these results suggest that transitional waters such as lagoons may serve as reservoirs for ARGs, and might be influenced by anthropogenic pressures and natural processes such as salinity fluctuation and nutrient cycling.

A Method to Quantify the Drainage Basin Contributions to Transitional Water Bodies: Numerical Modeling Applied to the Case Study of Venice Lagoon

A Method to Quantify the Drainage Basin Contributions to Transitional Water Bodies: Numerical Modeling Applied to the Case Study of Venice Lagoon

Transitional Infrastructures Extending Access to Safe Water in Informal Settlements: A Cross-Sectional Study in Nairobi, Kenya.

There is a pressing need for transitional water infrastructures in rapidly growing cities where conventional infrastructures lag behind human settlement expansion. In Kenya, sectoral innovations have addressed local socioeconomic challenges, but empirical evidence on their efficacy (combining quantitative indicators of safety and continuity) is lacking. We addressed this gap by comparing different water infrastructures in their ability to provide constant access to safe water in informal settlements in Nairobi, Kenya. We conducted a cross-sectional survey including 1,147 households in two informal settlements. Water infrastructures were categorized based on their distribution system: 1) piped to premises; 2) piped to a neighboring compound; 3) public tap/dispenser; and 4) street vendor. We tested associations between these systems with two outcomes: constant water availability and diarrhea (stratified by age group). We used adjusted odds ratios (AORs) to test associations between distribution systems and the selected outcomes, while accounting for confounders. Obtaining water from public taps/dispensers or street vendors was associated with service continuity (AOR = 1.45, 95% confidence interval [CI]: 1.06-1.99; AOR = 11.16, 95% CI: 2.45-50.82). Piped sources were associated with service disruption, especially when obtained from a neighboring compound (AOR = 0.45, 95% CI: 0.28-0.70). Public taps/dispensers were the only system consistently associated with lower odds of diarrhea, notably in children under the age of 5 years (AOR = 0.47, 95% CI: 0.29-0.79). Hence, in cities with a high prevalence of informal settlements and limited financial resources, public taps and dispensers hold promise as transitional water infrastructures.

Delivering effective and equitably governed marine protected area networks in the UK: The role of Inshore Fisheries and Conservation Authorities (IFCAs)

Against a backdrop of international commitment to establish effective marine protected area networks, UK marine policy is increasingly ambitious in its scope to designate a higher quantity and quality of marine protected areas. This ambition is not without challenge and controversy in an island nation with multiple competing demands spanning shipping, tourism, energy, conservation, and fisheries. This paper highlights the significant contribution of Inshore Fisheries Conservation Authorities (IFCAs), regional bodies responsible for commercial and recreational fisheries and conservation management in England’s coastal & transitional waters, to realising an effective national nearshore network of MPAs. Equitable governance in the IFCA context could be defined as a combination of i) the remit of balancing conservation with sustainable use that inherently incorporates a central and consistent consideration of the needs and rights of local communities and ii) democratic inclusive decision-making via the IFCA authority membership providing an empowered voice and vote to local communities who have a stake in and are affected by MPA proposals in their regions. Since their inception in 2011 the IFCA raison d’etre has been to deliver an appropriate balance between marine conservation and sustainable fishing agendas. This, along with widely recognised benefits of regionality and devolved powers, places experienced IFCA staff and members in a strong position to navigate many of the challenges of developing and expanding MPA networks that are both legitimate and effective. This paper lays out the case for why the IFCA model and mode of practice is tailored to deliver effective marine protected area networks that are equitably governed with attention to sustainable use and the livelihood needs of local communities. We present evidence from across England that demonstrates IFCA-led progress in MPA management. These include the use of IFCA byelaws to appropriately manage fishing impact, balancing sustainable use with effective marine conservation including prohibition of bottom-trawling in many protected areas, a form of fishing often criticised for undermining MPA efficacy.

Application of benthic foraminiferal indices to infer the ecological quality status in the Sepetiba Bay (SE Brazil)

The Sepetiba Bay (SB, SE Brazil) is a highly anthropized and industrialized area that has experienced severe environmental degradation in recent decades. This study applies a multiproxy approach to document the response of living benthic foraminifera to environmental stress and to infer the Ecological Quality Status (EcoQS) in SB. Our methodology involved a comprehensive comparison of the density and percentage of benthic foraminiferal species with physicochemical, textural, and geochemical data, specifically the concentrations of potentially toxic elements (PTEs). We also statistically compared two geochemical indices, the pollution load index (PLI) and the potential ecological risk index (PERI), with two ecological indices, the Tolerant Species Index (TSI) and the Exp(H'bc).The TSI and the Exp(H'bc) indices are significantly correlated with the environmental stressors in Sepetiba Bay, namely the PTEs concentrations (As, Cd, Pb, and Zn). The most tolerant species to the enrichment of PTEs and organic matter are Ammonia tepida (Cushman, 1926), Elphidium excavatum (Terquem, 1875), Ammonia buzasi Hayward and Holzmann, 2021 and Ammonia rolshauseni (Cushman and Bermúdez, 1946). The Exp(H'bc) and TSI reveal that most stations located in the inner zone and near the margins of the bay have poor and bad EcoQS, which agrees with the distribution of the environmental stressors.Thus, the current environmental conditions of the inner area of Sepetiba Bay are of great concern. This work also shows that using the TSI and the Exp(H'bc) indices, it is possible to classify EcoQS in transitional coastal environments in the North and South Atlantic transitional waters. This work has relevant scientific and social implications due to its importance in biomonitoring and the management of the coastal regions.

Spatial and temporal distribution of tributyltin in the coastal environment of the Croatian Adriatic (2016-2023): TBT remains a cause for concern

This work presents a spatial and temporal distribution of tributyltin (TBT) and TBT pollution assessment of the Croatian Adriatic coast in the period 2016 – 2023. The monitoring of TBT pollution was carried out within the Water Framework Directive (2000/60/EC) and the Marine Strategy Framework Directive (2008/56/EC). TBT concentrations were measured at 63 sites in coastal and transitional waters in three compartments - water, sediments and mussels. The ranges of TBT concentrations were <0.06 – 6.40 ng(TBT)/L in the water column, <1 – 2546 ng(TBT)/g(d.w.) in sediments, and <1 – 655 ng(TBT)/g(d.w.) in mussels, while transitional waters were in general more polluted than coastal waters. Monitoring of TBT concentrations in water showed that 30% of monitored sites were continuously polluted with TBT with average annual concentrations exceeding AA-EQS [0.2 ng(TBT)/L], while 20% of the sites had concentrations in sediments above the proposed EQS for sediments [1.6 ng(TBT)/g(d.w.)]. In mussels, TBT was detected at 70% of the sites with more than 60% of the sites exceeding the OSPAR criteria [12.6 ng(TBT)/g(d.w.)], indicating that the occurrence of imposex in gastropods at these sites is very likely. Only a slight decrease in TBT levels was observed over the investigated period, but concentrations at most contaminated sites did not fall below the EQS. This study shows that, despite the ban of TBT-based antifouling paints more than 15 years ago (except for public and military vessels), contamination of the Croatian Adriatic coast with TBT still exists and regular monitoring is essential. The TBT distribution was primarily determined by the vicinity of the pollution source, i.e. shipping traffic, but the role of physicochemical parameters, such as dissolved organic carbon (DOC) and transparency of the water column, should not be disregarded as well as the influence of hydrodynamics in the transitional waters. Although monitoring of TBT concentrations in water is an established approach to assess recent pollution, this long-term study has shown that mussels can be the most reliable indicator of pollution in a given area over the last several months.

Macrophytes as Key Element to Determine Ecological Quality Changes in Transitional Water Systems: The Venice Lagoon as Study Case

According to European Union guidelines, the assessment of the ecological status of Transitional Water Systems (TWSs) should be based on the monitoring of biological communities rather than physico-chemical parameters and pollutants. Macrophytes, including aquatic angiosperms and macroalgae, are organisms that respond more quickly to environmental changes by varying the structure and biomass of their assemblages. There are several ecological indices based on macrophytes, among them the Macrophyte Quality Index (MaQI), which has been intercalibrated with water and sediment parameters, nutrient concentrations, and pollutants and is used to determine the ecological status of Italian TWSs. In the Venice Lagoon, it was applied to 87 stations, showing a significant score increase over the last ten years of monitoring (2011–2021) due to progressive lagoon environmental recovery. The dominant taxa assemblages, previously dominated by Ulvaceae, were replaced by species of higher ecological value, with an increase in the number and distribution of sensitive species, as well as the spread and cover of aquatic angiosperms. The rise in the Ecological Quality Ratio (EQR) determined by the MaQI confirms the key role of macrophyte monitoring in detecting environmental changes in TWSs. In fact, a simple check of the presence or absence of aquatic angiosperms and sensitive species is sufficient for an initial rapid assessment of the ecological status of these environments.

The impact of the destruction of the Kakhovka reservoir dam on the oceanographic conditions in the north-western part of the Black Sea according to the results of modeling

Based on the results of numerical modelling, characteristic features of distribution of transformed and polluted waters of the Dnieper River in the water area of the north-western part of the Black Sea (NWBS) are determined and analyzed. This pollution of the marine environment resulted from the extremely large man-made flood caused by the destruction of the Kakhovka Reservoir dam by the Russian occupation forces in June 2023. Various types of pollutants, which contained in the Kakhovka Reservoir, in the lower Dnieper River and in the bottom sediments, were carried out into the sea by the flood discharge. A significant amount of pollutants was washed into the sea from the flooded areas of the lower Dnieper basin. Special attention is given to changes in oceanographic conditions in the Dnieper-Bug estuary region (DBR) of the Black Sea, which determine the extent of marine pollution. Sea water salinity was used as an indicator of the degree of infiltration of polluted seawater from the estuary into the sea. It was identified that the least transformed river waters with low salinity correspond to high pollution levels. Delft3D-Flow Flexible Mesh hydrodynamic model, developed by Deltares, was used in this study. The simulation was performed for the time period 01 to 30 June 2023. During the first days after the dam break the desalinated and polluted transitional waters, flowing from the Dnieper-Bug estuary, spread over the entire water column down to 15-20 m depth in the DBR area. In this case, the spreading of transitional waters was atypical, as it usually occurs only within the thin near-surface layer of the sea. By mid-June the flow of transitional water with a salinity of 4-6 ‰ covered the entire water column from surface to bottom near the northern coast of the NWBS and over the Odessa Bank. This was facilitated by the supermassive volumes of transformed Dnieper river waters flowing out over a short period of time due to dam break, as well as by the resulting intense gradient currents and mixing caused by spatial gradients in the velocity of the generated currents. The width of the desalinated water plume and its area in the bottom layer were smaller than in the surface layer. The largest vertical salinity gradients were formed to the south of the Odessa Bank, where salinity was 4-6 ‰ in the surface layer and 14-17 ‰ in the bottom. Dilution of the desalinated water plume in the bottom water layer was much more intensive than in the surface water. The character of water circulation pattern in the northern part of the NWBS in the first days after the inflow of transient waters from the Dnieper-Bug estuary was determined by the runoff gradient currents, which later were replaced by wind-driven currents in the Odessa area and over the Odessa Bank, and by the meandering flow of gradient density currents further south. The findings of this study contribute to a better understanding of the impact of the inflow of transformed river waters from the Dnieper-Bug estuary on the variability of oceanographic characteristics and the ecological state of marine waters in the Dnieper-Bug region of the northwestern Black Sea.

Framework for Regional to Global Extension of Optical Water Types for Remote Sensing of Optically Complex Transitional Water Bodies

Water quality indicator algorithms often separate marine and freshwater systems, introducing artificial boundaries and artifacts in the freshwater to ocean continuum. Building upon the Ocean Colour- (OC) and Lakes Climate Change Initiative (CCI) projects, we propose an improved tool to assess the interactions across river–sea transition zones. Fuzzy clustering methods are used to generate optical water types (OWT) representing spectrally distinct water reflectance classes, occurring within a given region and period (here 2016–2021), which are then utilized to assign membership values to every OWT class for each pixel and seamlessly blend optimal in-water algorithms across the region. This allows a more flexible representation of water provinces across transition zones than classic hard clustering techniques. Improvements deal with expanded sensor spectral band-sets, such as Sentinel-3 OLCI, and increased spatial resolution with Sentinel-2 MSI high-resolution data. Regional clustering was found to be necessary to capture site-specific characteristics, and a method was developed to compare and merge regional cluster sets into a pan-regional representative OWT set. Fuzzy clustering OWT timeseries data allow unique insights into optical regime changes within a lagoon, estuary, or delta system, and can be used as a basis to improve WQ algorithm performance.

Dense Water Formation Variability in the Aegean Sea from 1947 to 2023

The formation of dense water in the Aegean Sea is important as it affects the deep circulation and the hydrography of the Eastern Mediterranean Sea. In this study, the variability of dense water formation is investigated in relation to forcing mechanisms from 1947 to 2023 in the subbasins of the Aegean Sea, utilising in situ observations from various sources, which have been analysed in combination with satellite altimetry and reanalyses products. The analysis reveals that the Aegean Sea has been in a state of increased dense water formation since 2017 due to the combination of increased surface buoyancy loss and reduced Black Sea water inflow. Extremely high salinity has been recorded in the intermediate layers of the Aegean Sea since 2019. The anticyclonic circulation of the North Ionian gyre during 2017 and 2018 probably also contributed to the rapid transport of highly saline waters in the intermediate and, through dense water formation, the deep layers of the Aegean Sea in 2019. Until 2022, the dense waters formed during the peak of the Eastern Mediterranean Transient still occupied the bottom layers of some deep subbasins of the North and South Aegean; however, the 29.4 kg m−3 isopycnal in the North Aegean and the 29.3 kg m−3 isopycnal in the Southeastern Aegean have gradually deepened by 800 m, permitting the waters forming in the last ten years in the Aegean Sea to settle at ever greater depths. Temperature controls the density variability of the Cretan intermediate water up to the decadal time scale. Increased data availability since 2010 was sufficient to clarify that intrusions of dense water from the North–Central Aegean Sea contributed to the erosion of the Eastern Mediterranean transitional waters in the South Aegean Sea after 2017, as well as to raising the intermediate water masses of the South Aegean to shallower depths. The erosion of the transitional Mediterranean waters in the South Aegean Sea between 1947 and 1955 and 1973 and 1980 coincided with increased dense water formation in the North–Central Aegean Sea. During the peak of the Eastern Mediterranean Transient, the North Ionian circulation, the Black Sea water inflow, the Atlantic Multidecadal Oscillation, and the surface buoyancy fluxes favoured dense water formation in the Aegean Sea.

Assessing benthic macroinvertebrate communities’ spatial heterogeneity in Mediterranean transitional waters through eDNA metabarcoding

Transitional waters are important habitats both for biodiversity and ecological functions, providing valuable natural resources and relevant ecosystem services. However, they are highly susceptible to climate changes and anthropogenic pressures responsible for biodiversity losses and require specific biomonitoring programs. Benthic macroinvertebrates are suitable as ecological indicators of transitional waters, being affected by biological, chemical, and physical conditions of the ecosystems about their life cycles and space-use behaviour. The advent of high-throughput sequencing technologies has allowed biodiversity investigations, at the molecular level, in multiple ecosystems and for different ecological guilds. Benthic macroinvertebrate communities’ composition has been investigated, at the molecular level, mainly through DNA extracted from sediments in marine and riverine ecosystems. In this work, benthic macroinvertebrate communities are explored through eDNA metabarcoding from water samples in a Mediterranean transitional water ecosystem. This research highlighted the validity of eDNA metabarcoding as an efficient tool for the assessment of benthic macroinvertebrate community structure in transitional waters, unveiling the spatial heterogeneity of benthic macroinvertebrate communities correlated to the measured environmental gradients. The results suggest that peculiar features of transitional water ecosystems, such as shallow waters and limited currents, facilitate the assessment of benthic macroinvertebrate communities through environmental DNA analysis from surface water samples, opening for more rapid and accurate monitoring programs for these valuable ecosystems.

Cyanotoxins in Epipelic and Epiphytic Cyanobacteria from a Hypersaline Coastal Lagoon, an Environmental Hazard in Climate Warming Times and a Potential Source of New Compounds.

Cyanobacterial biodiversity and potential toxicity in coastal lagoons have barely been studied despite these transitional water systems being very important in conservation and for the preservation of economic resources. Most of these transitional systems have been affected by eutrophication, and climate change will severely affect them by promoting cyanobacteria growth, especially in Mediterranean areas. This study aims to characterize the diversity of epipelic and epiphytic cyanobacteria species in a Mediterranean coastal lagoon and their potential for toxins production (microcystins and saxitoxins). Strains were isolated and genetically identified. Toxins were extracted and quantified by LC/MS-MS. All the taxa belong to the former Oscillatoriales. The presence of Nodosilinea and Toxifilum is reported for the first time for Spanish waters, but Pseudanabaena, Phormidium, Geitlerinema and Synechococcus also formed part of benthic mats. All the strains contained Microcystin-YR (MC-YR), but saxitoxin (STX) was present only in the extracts of Nodosilinea and Pseudanabena. MC-LY, MC-LW and [D-Asp3] MC-LR were detected in the extracts of Synechococcus and MC-LF in Toxifilum, but at concentrations that did not permit quantification. Toxins production by epipelic and epiphytic strains in coastal lagoons may represent a hazard, but also an opportunity to obtain potentially interesting compounds that should be further studied.

Validation of full resolution remote sensing reflectance from Sentinel-3 OLCI across optical gradients in moderately turbid transitional waters

Validation of full resolution remote sensing reflectance from Sentinel-3 OLCI across optical gradients in moderately turbid transitional waters

Paleolimnological Investigations in Coastal Sarıkum Lagoon, Sinop, Turkey

Lagoons are dynamic systems, making ecosystem management difficult. Paleolimnological approach is the only way to track past long term environmental changes and background conditions that are essential to build environmental management plans. Here, we investigated a sediment record from Sarıkum Lagoon, on the Black Sea coastal plain in North Anatolia, through a multiproxy paleolimnological approach to reveal long term environmental change and background conditions in the lake. For which, dry weight, organic and carbonate carbon, chlorophyll a (including its main diagenetic products), magnetic susceptibility and ostracod analysis were undertaken. The core was dated via radionuclide technique. At around 30 cm of the sediment record, there are abrupt transitions in all proxies, indicating a massive sediment input, a transition from transitional water to lacustrine environment, and lake’s biota also changed. Biological proxies preserved in the sediments suggest that the latest zone, after this event, is represented by lacustrine and hydrologically more isolated conditions from the Black Sea. Whatever the reason of that event (e.g. earthquake, flood), Sarıkum Lagoon has had lacustrine conditions during the last ~ 2 and half centuries following that abrupt event. This long term environmental change information should be considered while making future ecosystem management and conservation plans for the lake. (e.g. keep the lake connected with the Black Sea).

Native and Non-Indigenous Biota Associated with the Cymodocea nodosa (Tracheophyta, Alismatales) Meadow in the Seas of Taranto (Southern Italy, Mediterranean Sea)

The collection of photos during the systematic monitoring activities is useful to witness the ecological role of marine phanerogams as hosts for a rich variety of organisms in coastal and transitional waters. Cymodocea nodosa is present in the Taranto seas. In Mar Piccolo, it reached high coverage in a short amount of time, up to 100%, due to the improvement in environmental conditions. The most recent observations showed that it offers a welcoming habitat for several vertebrates and invertebrates, native and non-indigenous, as well as to micro- and macroalgae. The NPPR-funded activities will make these observations more robust and structural.

Migratory pathways and winter destinations of Northern Gannets breeding at Helgoland (North Sea): known patterns and increasing importance of the Baltic Sea

We analysed the migratory behaviour of adult Northern Gannets (Morus bassanus) breeding at Helgoland in the North Sea, based on data obtained from geolocation devices in the non-breeding season 2016–2017. Birds moved east and south-west to a broad range of wintering sites, ranging from the western Baltic Sea to North-West Africa. Three out of 12 birds spent the winter in Africa, while 9 birds wintered in Europe, with the primary wintering sites in the North Sea. All but one tagged bird spent some time in the Baltic Sea or in the transitional waters between the North Sea and Baltic Sea. We also analysed data from online databases (dofbasen.dk, ornitho.de) and the German Seabirds at Sea database to explore the extent to which Northern Gannets used the western Baltic Sea, as well as the Kattegat and Skagerrak, during the winter months. Records of Northern Gannets in Danish waters have increased substantially over the last 18 winters, with particular increases in the Baltic Sea. There was also a notable increase in sightings of Northern Gannets in German Baltic Sea waters, but this occurred later than in the more northerly Danish waters. Both analyses demonstrated that Northern Gannets explored the western part of the Baltic Sea, as well as the Kattegat and Skagerrak, increasingly intensively. This recent increase in sightings is in accord with the establishment and exponential increase in the nearest breeding colony of Northern Gannets at Helgoland.

Black Sea Eutrophication Comparative Analysis of Intensity between Coastal and Offshore Waters

Eutrophication, driven by excessive nutrient enrichment from sources like agricultural runoff, industrial discharge, and urbanisation, has severely impacted the Black Sea since the 1980s. This study aimed to assess eutrophication dynamics in the Romanian Exclusive Economic Zone from 2020 to 2022 using the Black Sea Eutrophication Assessment Tool (BEAST), an integrated approach to the causes and effects of eutrophication. Data were collected from 68 stations during five oceanographic expeditions, analysing 617 water samples for nutrients, chlorophyll a, zooplankton species Noctiluca scintillans, and dissolved oxygen. Additionally, 179 zoobenthic and 251 phytobenthic community samples were collected. The results indicate that coastal waters exhibit higher nutrient levels and algal blooms compared to offshore waters, necessitating significant reductions in nutrient concentrations to achieve good environmental status. In transitional waters, within the Danube Delta Biosphere Reserve, a 55% reduction in inorganic phosphorus and a 43% reduction in inorganic nitrogen concentrations are required, while coastal waters need reductions of 38% and 37%, respectively. The study highlights the need for improved wastewater treatment, stricter agricultural runoff controls, and continuous monitoring. Effective ecosystem-based management strategies, integrated coastal zone management, and international cooperation are essential to mitigate eutrophication and promote the long-term health of the Black Sea ecosystem.