Microplastics and mesoplastics have become integral components of marine debris and the broader global plastic pollution crisis. Their increasing prevalence and environmental hazards have driven worldwide monitoring efforts, often alongside beach macrolitter surveys, to establish source linkages critical for informed policy and management. Employing standardized sampling protocols, this study establishes baseline spatiotemporal dynamics of microplastics (1-5 mm) and mesoplastics (5-25 mm) in the Republic of Cyprus, characterises their typologies and identifies key contamination drivers. It further introduces a newly improved attribution scheme to evaluate shoreline vulnerability to debris loads arising from distinct transport pathways. Mean abundances recorded were 336 particles m-2 (0.819 g m-2) for microplastics, 107.5 particles m-2 (1.086 g m-2) for mesoplastics, and 0.459 items m-2 for beach macrolitter. Particle loads exhibited heterogeneous physical profiles and fine-scale spatial variability, influenced by hydrodynamic exposure and temporal factors, with particle retention likely governed by coastal morphology. Approximately 69% of shorelines were susceptible to sea-based debris, 6% to land-based inputs, and 25% being heavily impacted by marine-derived plastic pollutants. These findings underscore the magnitude of marine debris contamination in the eastern Mediterranean and emphasise the necessity of an integrated, multi-faceted monitoring approach that enables local authorities to allocate resources strategically, tailored to dominant transport pathways, for effective plastic pollution management and mitigation.

We thank Galil and Rinkevich for their interest in our recent publication [...]

Seaweed aquaculture is a growing blue sector that provides many benefits to society (e.g. biomass provision for food, feed and cosmetics) and the environment (e.g. eutrophication mitigation, carbon uptake and habitat provision). Successful and sustainable production expansion requires that these activities are operated within limits of acceptable change (LAC) i.e. align with ecological and social carrying capacity. Emerging from a three-round Delphi study, this work presents, from a Global North perspective, the most relevant 1) limiting variables from the socio-environmental spheres that influence the cultivation unit (inputs), such as high operating costs or underdeveloped markets or uncertain impacts from climate change, and 2) the negative impacts of aquaculture on environment and society (outputs), such as overhyped and unrealistic expectation for seaweed cultivation, conflicts with fisheries or pollution. Consolidated lists of these inputs and outputs are accompanied by specific thresholds beyond which unacceptable changes are likely to occur. These results are placed into a globally applicable holistic framework for a multidimensional assessment of seaweed aquaculture including barriers and carrying capacity, which has been outlined for the first time for seaweed cultivation. Our results emphasize the need to include socio-economic aspects into ecosystem approaches, like profitability or social license to operate-and the need for broad stakeholder participation. This study provides thus a directly useable lists of aspects to consider for cultivators and decision-makers. And as is as such a crucial contribution for the ongoing discourse on sustainable growth of this emerging blue sector.

Since it was first observed in Israel in the 1970s, and due to its subsequent negative impact on human activities, the nomad jellyfish Rhopilema nomadica has earned itself a spot on the list of the 100 Worst Invasive Alien Species in the Mediterranean. It was assumed to originate in the Red Sea, or in the Indo-Pacific region, but in the absence of additional reports of live specimens outside the Mediterranean, its origins have remained a mystery. Here, via molecular analysis, we present the first verified results of the existence of R. nomadica in the Western Indian Ocean. Moreover, using additional evidence from Cassiopea andromeda and R. nomadica, we propose that the construction of the Aswan High Dam may have led to the proliferation of R. nomadica in the Levantine Basin.

Abstract Gelatinous zooplankton are abundant predators and prey in marine food webs, yet their role in helminth (parasitic worms) transmission remains poorly resolved. Here we combine a global synthesis of published records with new morphological and molecular observations from the Mediterranean, Red, Celtic, Baltic and North Seas to assess the ecological role of helminths associated with gelatinous zooplankton. We compiled 432 host–parasite association records from 90 sources, including 23 new records, and show that helminth occurrence and richness in gelatinous hosts are concentrated at temperate latitudes, contrasting with the classical latitudinal diversity gradient. Our sampling revealed markedly higher parasite prevalence, abundance and diversity in the Red Sea than in the Mediterranean, while no helminths were detected in gelatinous zooplankton sampled from the Baltic and North Seas. All helminths recorded were larval stages, indicating that gelatinous zooplankton function as key intermediate hosts in marine helminth life cycles. Molecular analyses identified cestodes, nematodes and digenean trematodes associated with cnidarians, ctenophores, and chaetognaths, including the first record of trematode larvae in a pelagic tunicate. Our findings challenge the view of gelatinous zooplankton as trophic dead ends and identify them as overlooked hosts that may shape marine parasite biogeography, food-web connectivity and invasion dynamics.

The Mediterranean Sea has a substantial volume of maritime traffic, including many tankers ferrying oil from eastern sources to western refineries. This critical maritime front, vital for trade and connectivity, also poses a significant risk of oil spills due to these busy shipping routes. The conventional methods for early oil spill detection have encountered numerous challenges, primarily due to the complex and variable nature of spill events. This study promotes an anomaly-based approach, treating oil spills as environmental outliers, and utilizes baseline water parameter comparisons to detect and monitor sea oil spills effectively. This approach leverages satellite data, employing a combination of remote sensing techniques and advanced machine learning technologies. The end goal is providing a platform for monitoring and detecting oil spills, to empower users worldwide to conduct regular assessments, contributing to the proactive prevention of future environmental damage.

Synthetic microfibers are a class of microplastics routinely released into environmental media from domestic laundry and wastewater treatment plant effluent. Areas of high human population density discharge immense amounts of synthetic microfibers that pollute and accumulate in sediments, surface waters, algae, and other parts of the ecosystem. Synthetic microfibers are abundant in the Laurentian Great Lakes of North America, but their movement and fate are not well understood. Macroalgae effectively sequester microfibers; however, it is unknown if quantities of synthetic microfibers differ in benthic algae of the Great Lakes based on human population density or algal type (such as Cladophora or charophytes). Presented here is a 4-year study that investigated benthic algae samples from four of the Laurentian Great Lakes: Lakes Michigan, Huron, Ontario, and Erie. Synthetic microfibers were isolated and quantified in the algal samples, and values were analyzed with respect to algal type, lake, and population density. The average estimated number of synthetic microfibers per kg (dry weight) of benthic algae in each lake ranged from 1.6 x 104 to 2.0 x 104. Microscopic analysis suggested a possible interaction between epiphytic diatoms and benthic macroalgae (Cladophora), which may help to explain the ability of the algae to sequester microfibers regardless of algal type. The results also suggest a lack of correlation between human population density and number of synthetic microfibers in benthic algae, which could imply facile movement and distribution of microfibers in large bodies of water, that includes the aquatic food web of macroinvertebrates and fish communities.

Rhopilema nomadica is the most prominent jellyfish species in the eastern Mediterranean, forming huge annual summer swarms. Although planula settlement success is essential in the formation of jellyfish outbreaks, quantitative studies to examine its response to environmental variables have not been performed thus far due to the difficulty in collecting planulae. We concentrated large numbers of R. nomadica planulae to study the effect of substrate type and seawater temperature on planula settlement. In the substrate preferences experiment, two natural substrates (bivalve shells and kurkar rock) and two artificial substrates (concrete and plastic (PVC)) were offered for planula settlement. Settlement success was not different between concrete, PVC, and kurkar substrates, but was significantly lower on the shells. In the temperature experiment, planulae were able to settle and metamorphose into polyps at all five temperatures (16—32 °C) tested, on glass slides, and most settled within three days. Higher temperatures were not only associated with accelerated settlement but also increased settlement success. The anticipated increase in marine infrastructures (potential settlement substrates), and rising seawater temperatures may favor planula settlement success and further enhance outbreaks of R. nomadica in the Mediterranean.

We present Citizen Science-based Jellyfish Observation Initiatives (CS JOIs) across the Mediterranean Basin and propose a path toward standardization of the data they produce. We explored data collection and management through a shared database schema. Using an expert opinion questionnaire and adhering to standards that are recognized globally (e.g., by GBIF, OBIS, and EMODnet) such as Darwin Core and IOOS terminology, we propose a three-stage approach toward data management and standardization. JOIs vary in purpose, function, language, data collection, validation methodology, outreach, and levels of citizen engagement and training. This diversity presents unique opportunities and challenges for data collection and management. JOIs typically combine the dual role of providing real-time alert systems and enhancing our long-term knowledge of jellyfish distribution and, eventually, ecology. When global reporting systems are considered, local initiative identity, language, purpose, and community must be preserved to allow meaningful CS processes to evolve, while the integration of JOIs within them (and data collection and management in general) must be performed via standardized and shared methodologies. Finally, we discuss the contribution of novel technologies toward improving the activities and management of JOIs worldwide.

Marine litter monitoring is a key component in management that foster conducive progress along the world’s coastlines. In the absence of long-term efforts, historical data deem crucial for assessing coastal litter, particularly in understudied regions. This study highlights the pivotal role of environmental NGOs working with citizen scientists through proactive clean-up and data collection initiatives during periods when research and national monitoring efforts were lacking in the island of Cyprus. The outcome of these initiatives provided invaluable insights into the historical state of Cyprus’s coastal fronts, bridging critical data gaps essential for informed policymaking. The results underscore the harmful and variable nature of coastal litter and the persistent pollution rates observed from 2014 to 2018. Most anthropogenic debris was mainly plastic, originating from recreational activities of visitors, deliberate dumping, and sea-based transport. While subsequent studies showed an improvement of litter densities by 2021, this decline is largely attributed to the COVID-19 lockdowns, and heightened awareness alongside intensified clean-up efforts. To sustain long-term clean coasts, clean-ups play an imperative role as tools for awareness and monitoring. Local authorities worldwide ought to reconcile economic instrument strategies to minimise littering behaviour and invest in research and development to tackle marine debris, aligning with the precious plastic concept.

Microplastics (MPs) (<5 mm) are persistent and ubiquitous pollutants in aquatic environments, with over 80% originating from terrestrial sources. While their presence in the Mediterranean Sea has been documented, studies on MP inputs via local streams remain limited. This study quantified and characterized MP abundances along the Na’aman stream (Israel) and its outlet to the Mediterranean Sea, with samples collected before, during, and after the rainy season from established transects along the streambank and from the nearby beach. The spatial distribution and abundances of MPs were examined in relation to seasonal and hydrological conditions. MPs were sorted by type and counted by dissecting microscope. A representative subset of putative MP particles was examined using Fourier transform infrared spectroscopy. The overall mean (±standard error) MP abundance for the Na’aman stream was 231 ± 67 particles kg ^−1 sediment dry weight, with significant seasonal and spatial variation. MP accumulation increased during dry months and decreased sharply following flood events—dropping by 43% after a 13 mm rainfall event that triggered stream discharge of 3.25 m ^3 s ^−1 , highlighting the stream’s role in flushing MPs to the sea. The most common MP types were fragments (61.9%), fibers, and foam, with polypropylene accounting for 56.9% of analyzed particles. MP types and polymer compositions varied by site and season, suggesting diverse sources such as domestic wastewater, agriculture, and marine backflow. These findings confirm that ephemeral stream systems can temporarily trap and subsequently remobilize MPs, acting as critical conduits between land-based sources and the marine environment. Targeted mitigation efforts—such as seasonal cleanup campaigns just before the rainy season—could significantly reduce MP flux to the sea in this location. This is the first documented assessment of MP transport from a freshwater stream into the Mediterranean Sea in Israel and may serve as a baseline for future monitoring in similar Mediterranean-climate regions.

Ocean-based carbon dioxide removal (CDR) strategies increasingly consider biomass burial in anoxic marine basins as a pathway for long-term carbon storage. To evaluate its stability and environmental impact, we conducted 14-month bottle incubations testing three configurations of terrestrial wood under anoxic conditions: suspended in the water column, placed on the sediment surface, and buried within sediments. Across all treatments, wood remained highly preserved: >97.5% carbon retained, based on C content, ~98.3% via carbon budgets, and >96% based on dry mass retained. Geochemical signals indicated that sulfate reduction was the dominant terminal pathway: dissolved inorganic carbon and alkalinity increased in nearly a 1:1 stoichiometry, methane yields were low relative to Dissolved Inorganic Carbon (DIC), and sulfide was presumably sequestered into iron sulfide minerals. Microbial community analyses corroborated these patterns, showing enrichment of fermenters and sulfate reducers with only minor contributions from methanogens. Dissolved organic carbon (DOC) dynamics further revealed sediment contact as a key control on DOC retention, with suspended wood yielding the most significant DOC accumulation. We observed no mobilization of toxic metals and only minor changes in major cations during the 14 months. Together, these results demonstrate that geochemical and microbial processes act in concert to preserve biomass carbon under anoxic conditions, highlighting marine burial as a durable, low-risk CDR strategy.

Rhizostoma pulmo (Macri 1778) is a common and large scyphomedusa in the Mediterranean Sea with a metagenetic life cycle. The polyps of this species have not been observed in natural habitats and there is limited knowledge regarding its benthic stages. Therefore, maintaining polyp stocks in the laboratory is essential for conducting experiments aimed at acquiring ecological insights. In this study, we collected R. pulmo polyps from wild medusae to investigate the environmental factors that promote their development in natural habitats. Sexually mature R. pulmo medusae (34.8 ± 7.4) were collected in the harbour of Sète (43°24’06.3"N 3°43’10.5"E) in August 2023. To investigate the early life stages of their benthic phase, the medusae were placed in tanks with controlled conditions to stimulate reproduction. We examined substrate preferences and vertical recruitment of planulae, and further tracked the developmental stages of polyps. We did not detect planula preference for a specific depth in the laboratory experiments, instead we observed that planulae exhibited a preference for settling on glass slides and polystyrene Petri dishes over mussel shells, with a greater abundance observed on the undersides of the settlement substrates.

This study investigates the synergistic effect of jellyfish mucus and commercial coagulants on the removal of microplastics (MPs) and nanoplastics (NPs) from water. The results reveal that combining low doses of jellyfish mucus (0.8 and 2 mg L- 1) with commonly used coagulants, such as ferric chloride (FeCl3) and polyaluminum chlorohydrate (PAC) significantly enhances the removal efficiency of MPs and NPs (>90 %) and reduces particle settling times to < 5 minutes. Mechanistic insights demonstrate that jellyfish mucus facilitates entrapment and bridging mechanisms, which play a key role in the aggregation and removal of plastic particles. Zeta potential measurements further confirm the neutralization of particle surface charges, with optimal conditions observed at 2 mg L- 1 jellyfish mucus and 2.5 mg L- 1 coagulant. Additionally, the Deryagin-Landau-Verwey-Overbeek theory explains these interactions, highlighting the entrapment and bridging effects for polystyrene nanoplastics (PS-NPs) and polymethyl methacrylate nanoplastics (PMMA-NPs), while a significantly higher interaction energy for carboxylatemodified PS microspheres (PS-CA-MPs) suggests the involvement of additional forces. This study underscores the promising role of jellyfish mucus-coagulant synergy in enhancing the removal of NPs and MPs from water, offering a sustainable and effective alternative to conventional water treatment technologies for plastic pollution mitigation.

With mounting global concerns about jellyfish outbreaks, monitoring their occurrence remains challenging. Tapping into the wealth of digital data that internet users share online, which includes reports of jellyfish sightings, may provide an alternative or complement to more conventional expert-based or citizen science monitoring. Here, we explore digital footprints as a data source to monitor jellyfish outbreaks along the Israeli Mediterranean coast. We compiled jellyfish sighting data for the period 2011-2022 from multiple platforms, including leading social media platforms, searches in the Google search engine, and Wikipedia page views. Employing time series analysis, cross-correlation, and various evaluation metrics for presence/absence data, we compared weekly data from three sources: digital footprints, citizen science, and traditional expert-based field monitoring. Consistent seasonal patterns emerge across datasets, with notable correlations, particularly in jellyfish abundance. The cross-correlation between digital footprint and citizen science data exceeds > 0.7, with Twitter and Instagram showing the highest correlation. Citizen science data often precedes digital footprints by up to one week. Correlation with traditional, expert-based field monitoring is limited as a result of limited data availability. Digital footprints demonstrate substantial agreement with the other data sources regarding jellyfish presence/absence and major outbreaks, especially for data from Wikipedia, Twitter, and Instagram. Overall, we highlight digital footprint data as a reliable, cost-effective tool for passive monitoring of jellyfish outbreaks, which can aid characterization in data-scarce coastal regions, including retrospective assessment. Transferring and scaling up the proposed approach should consider data accessibility as well as platform relative popularity and usage in the regions under investigation.

Global events such as the COVID-19 pandemic and regional events like the wars in Ukraine and in Gaza have affected and still affect global supply chains, including those for food. This has increased awareness of the importance of local food production, including aquaculture and mariculture. In this study, we point out and calculate the economic values of environmental sustainability and food security inherent in local production versus import alternatives. We present a case study involving the environmental effects and food security of supplying sea fish to the Israeli market from local production versus imports. The results show that increasing the consumption of seabream in Israel from imports, rather than local production, causes substantial external costs by increasing environmental damage due to increased transport and increasing potential food insecurity. Decision-makers should take these costs into account when deciding on a policy to support local aquaculture.

Within the framework of Ecosystem Approach to Aquaculture (EAA), ecological carrying capacity (ECC) is a key concept that helps to determine the upper limit of production without compromising ecosystem functioning. The implementation of ECC is complex as ECC differs between type of farms and location and standardised methods should be developed for management. There is therefore a clear need for operational indicators. The objectives of this paper were: (1) to carry out a systematic literature review on shellfish and seaweed aquaculture-environment interactions to list the most used environmental indicators, (2) to classify the indicators according to the effects they measure (i.e., benthic, water quality, food web interactions, cultured organism health, resource use) and the scale at which they are applied, and (3) to assess their potential based on four indicator criteria categories: sensitivity, accuracy and precision, feasibility and utility, and ecosystem-level scalability. Overall, indicators describing benthic effects were the most highly cited and scored. Indicators identified for bivalve and seaweed culture were discussed and compared to previous work on salmon aquaculture indicators to highlight similarities and differences across trophic levels. In addition, questions related to the challenges of ECC indicators implementation were presented to a panel of experts. The scoring and consultation provided the source of discussion on environmental management consistent with EAA.

Since first reported in the eastern Mediterranean in the 1970s, the swarm-forming scyphomedusa, Rhopilema nomadica, has been continuously expanding westward. We examined the effect of temperature on the benthic stages of this jellyfish (polyps, podocysts, and strobilae) to assess whether it can survive and reproduce in the western Mediterranean temperature regime (12.2-26.2°C). In the first experiment, polyps and podocysts were maintained at 4 constant temperatures (12, 18, 24, and 30°C) for 55 d. In the second experiment, temperatures were gradually reduced over 14 d, kept constant for 18 d, and then gradually brought back to 25°C. High temperatures proved beneficial to polyp survival and asexual reproduction, yet in some cases, polyps were able to survive temperatures as low as 12°C. Strobilation occurred at temperatures between 22 and 30°C. Podocyst production, excystment, and strobilation all take place following a temperature increase, and excystment of podocysts occurs mainly during the first 2 wk following podocyst production. We propose that the role of podocysts in R. nomadica is mainly to increase the current season’s polyp population, contributing to swarm formation rather than as a means to maintain polyp populations during harsh environmental conditions. Since polyps are able to survive winter temperatures in the western basin (12°C) and reproduce by podocysts and strobilation during summer temperatures (24°C), thermal constraints will probably not restrict the expansion of R. nomadica into the western Mediterranean. Expected future climate change conditions will increase the performance and range expansion of this species.

Since it was first observed in Israel in the 1970s, the ‘nomad jellyfish’ Rhopilema nomadica has established a reputation as one of the worst invasive species in the Mediterranean Sea. It was assumed to originate in the Red Sea, or in the Indo-Pacific region, but in the absence of additional reports of live specimens outside the Mediterranean, its origins remained a mystery. Here, via molecular analysis, we present the first verified results of the existence of R. nomadica in the Western Indian Ocean. Moreover, using additional evidence from Cassiopea andromeda and R. nomadica , we propose that the construction of the Aswan High Dam may have led to the proliferation of R. nomadica in the Levantine Basin. ### Competing Interest Statement The authors have declared no competing interest.

Most host-parasite associations are explained by phylogenetically conservative capabilities for host utilization, and therefore parasite switches between distantly related hosts are rare. Here we report the first evidence of a parasitic spillover of the burrowing sea anemone Edwardsiella carnea from the invasive ctenophore Mnemiopsis leidyi to two scyphozoan hosts: the native Mediterranean barrel jellyfish Rhizostoma pulmo and the invasive Indo-Pacific nomad jellyfish Rhopilema nomadica, collected from the Eastern Mediterranean Sea. Edwardsiella carnea planulae found in these jellyfish were identified using molecular analyses of the mitochondrial 16S and nuclear 18S rRNA genes. Overall, 93 planulae were found on tentacles, oral arms, and inside of the gastrovascular canals of the scyphomedusae, whereas no infection was observed in co-occurring ctenophores. DNA metabarcoding approach indicated seasonal presence of Edwardsiella sp. in the Eastern Mediterranean mesozooplankton, coinciding with jellyfish blooms in the region. Our findings suggest a non-specific parasitic relationship between Edwardsiella carnea and various gelatinous hosts based on shared functionality rather than evolutionary history, potentially driven by shifts in host availability due to jellyfish blooms. This spillover raises questions about the ecological impacts of parasitism on native and invasive scyphozoan hosts and the potential role of Edwardsiella in controlling their populations.