ABSTRACT Plant litter decomposition in rivers is shaped by multiple environmental conditions, which are modified by riparian zone characteristics and human activities, thereby impacting in situ plant litter decomposition rates. However, disentangling the relative importance of these conditions for plant litter decomposition rates is challenging without large‐scale studies encompassing wide environmental and anthropogenic gradients. We carried out a continental‐scale study on plant litter decomposition in 72 river locations across 7 catchments in Europe (Germany, Italy, Portugal, Spain, Sweden), representing wide gradients in climatic conditions, riparian zone characteristics, land‐use intensity, and human population density. We used remote sensing data and field surveys to quantify catchment, riparian, and river habitat characteristics. To assess decomposition rates, we used standardized wood sticks as a model substrate, representing a globally important source of organic matter in river systems. Wood decomposition rate (percent mass loss per day) increased by 4.3% per 1°C rise in mean annual air temperature but decreased by 3.4% per 10 people increase in population density (per 3.14 km2), 2.3% per 100 mm increase in mean annual precipitation, and 0.5% per 1 m increase in channel width. Land‐use intensity and riparian zone characteristics showed no significant effects on wood decomposition rates across the studied gradients. Our results show that wood decomposition rates in the studied rivers are likely to increase linearly with ongoing global warming, reducing the longevity of wood substrates and their reliability as carbon sinks. However, this warming effect might be offset in rivers experiencing concurrent increases in precipitation and human population density. Consequently, the net effect of global change on wood decomposition rates in rivers may be difficult to predict.

Temporary ponds represent fragile habitats that host species of high ecological and conservation interest. High-altitude ponds, although often considered pristine environments, may instead act as important sinks for anthropogenic macrolitter. This study, conducted in eight temporary ponds at Nufenen Pass (Switzerland, 2478 m a.s.l.), aimed to assess the abundance and characteristics of anthropogenic macrolitter in these habitats, focusing on key aspects such as polymer type, origin, shape, size, and color. A total of 56 macrolitter items were recorded, with an average of 7.0 ± 14.8 items per pond, corresponding to 0.002 ± 0.004 items/m2. Among macrolitter items, most plastics (82%) consisted of food-related packaging (50%), artificial plants (15%), bottle labels (11%), and shotgun cartridges (4%), with smaller numbers of twist ties, clothing labels, cables, fruit boxes, and plastic rings. Non-plastic litter (18%) included bolts, cans, can tabs, aluminum packaging, and paper food packaging. The size of macrolitter was highly variable, with a total length of 695.5 cm and an average of 12.4 ± 15.4 cm per item. The most common polymers for plastics were PO hard (n = 26) and PO soft (n = 16). Macrolitter density increased significantly with pond area (R2 = 0.73, p = 0.006), while a negative effect of distance from the restaurant present in situ was observed, with density decreasing as distance increased (R2 = 0.58, p = 0.03). We reported for the first time the presence of macrolitter accumulated in alpine temporary ponds, showing alarming density of items and calling for immediate management actions.

Riparian zones are transitional habitats linking terrestrial and aquatic ecosystems and connecting diverse socio-ecological landscapes within catchments. They naturally support high biodiversity and provide multiple ecosystem services, yet they have been extensively modified and degraded by human activities. Although Europe has established binding nature restoration targets, the absence of a standardised framework for riparian ecosystems across countries often leads to management inconsistencies, further complicated by differing stakeholder perceptions of threats and priorities. We surveyed stakeholders’ views on the ecological roles, threats, and management needs of riparian zones across five European countries (Sweden, Germany, Spain, Portugal and Italy). Responses from more than 500 participants show strong alignment between scientists and practitioners. Approximately half of all respondents considered their local river basins to be in low to moderate condition. Perceptions of key threats varied geographically: invasive species were viewed as a major concern in the Iberian Peninsula, whereas habitat modification was broadly recognized as a critical issue. Conversely, Swedish respondents viewed water-quality degradation as a minor threat. Management priorities also differed regionally, with German respondents frequently emphasising restoration, while Portuguese prioritised environmental education. Awareness of European eco-schemes supporting riparian restoration was generally low, particularly in Sweden. Ultimately, our large-scale survey reveals both shared and divergent stakeholder perspectives that mirror the environmental and ecological characteristics of riparian zones across Europe’s boreal, continental, Atlantic and Mediterranean ecoregions. These findings underscore the need to improve awareness of financial incentives and to strengthen support for riparian conservation and restoration across the EU.

Every day, millions of tons of plastic debris are poured into rivers from industrial and civil waste or due to social carelessness and transported to the ocean. Here they decompose into small fragments, compromising the health and growth of fauna and flora that ingest or absorb them. In recent years the idea of using vegetation to trap and extract plastic waste has developed to limit this phenomenon. The aim of this work is to experimentally quantify the ability of aquatic vegetation in trap plastic and understand whether different biotic factors, hydraulic conditions or debris type influence it. Three of the most abundant macrophytes in European and Asian rivers are tested in this study, Myriophyllum spicatum, Potamogeton crispus and Phragmites australis. Natural samples of vegetation, taken along the Tiber, Ninfa-Sisto and Aniene rivers, are positioned into a recirculating flume, where the flow rate and the water depth can be varied. Once stationary flow conditions are reached, a known quantity of polystyrene fragments of different sizes (macroplastics, mesoplastics and microplastics) is added in the upstream part of the channel. The ratio between the fragments retained in the green barrier and the total added during the experiment defines the species' capacity to retain plastics. A change in seasonality, simulated by changing the water depth and the number of stolons inserted into the flume, is tested and its effects on the trapping efficiency is analysed. Three plant’s densities and two water depths are tested for each species. All three plant species show to effectively retain large and medium-sized plastic debris. Only the Myriophyllum spicatum, whose needle-like leaves form a denser network than the other two species, is also found to be efficient in retaining microplastics. The density of the area occupied by vegetation affects the number of trapped fragments, which increases for all species as the number of inserted stolons increases. The change in water depth has no significant impact on the results obtained. In conclusion, the three macrophyte species analyzed in this work can be used to create a barrier to the transport of plastics from rivers to oceans. A more complex structure of the vegetation allows the trapping of microplastics. A larger density of the area occupied by vegetation induces larger trapping efficiency, while hydraulic conditions appear to have no significant influence for the values tested in this study.

Mismanaged solid waste and plastics pose a significant global environmental challenge, affecting ecosystems from coastlines to the deep-sea basin. This study provides a comprehensive assessment of anthropogenic marine litter on fourteen popular tropical tourist beaches along the west coast of India, Eastern Arabian Sea. We examined the litter composition, spatial distribution, probable sources, and the role of regional hydrodynamics in litter accumulation. A total of 8409 litter items spanning 36 categories were identified during field surveys, with an average density of 1.82 f 0.53 items m-2. Litter density was higher in the high tide zone (2.35 f 0.31 items m-2; ranged: 0.81-4.48 items m-2), compared to the low tide zone (1.29 f 0.26 items m-2; ranged: 0.49-3.28 items m-2). Similarly, the average litter weight was 13.19 f 1.75 g m-2 in the high tide zone and 9.01 f 1.50 g m-2 in the low tide zone. Beach quality indices, including the Clean Coast Index and General Index, classified beaches as moderately to severely dirty, while the Hazardous Item Index placed them in categories II and III due to significant hazardous litter presence. The Clean Environment Index further identified half the beaches as dirty or very dirty. The findings suggest that litter primarily originates from tourism, fishing, and improper disposal practices. While regular beach clean-up initiatives mitigate litter accumulation to some extent, they provide only short-term relief and do not address fundamental drivers such as inadequate waste management infrastructure, high rates of solid waste and plastic production, and public littering behavior. Sustainable strategies, including source control, improved waste disposal systems, circular economy initiatives, and public behavioural changes, are essential to mitigate marine litter pollution effectively.

The interaction between freshwater biota and microplastics (MPs) has recently been described, mostly focusing on indoor experiments using fish, crustaceans, and chironomids. Among aquatic invertebrates, although having an important ecological role, aquatic butterfly larvae have not yet been investigated concerning plastics. We examined the interaction between aquatic larvae of the moth Cataclysta lemnata (Linnaeus, 1758) and MPs. We verified if (i) larvae could use MPs to build their protective cases, (ii) they could chew PVC, and (iii) there were effects on the pupae emergence to adult moths after larvae exposure to PVC. By performing two indoor experiments, (i) we exposed larvae to different MPs polymers, aquatic plant Lemna minuta, and a mix of MPs with L. minuta, and (ii) exposed larvae to a PVC layer. For the first time, we observed that C. lemnata larvae use MPs to build their cases and chewed the PVC layer. About half of the larvae (48.0%) pupated of which 43.7% emerged as adults. Our findings suggest that MPs are used by C. lemnata larvae, potentially affecting their life cycle. Future studies should explore whether MPs are transported by adult moths, linking aquatic and terrestrial ecosystems.

Among macro-litter, glass bottles are one of the most important categories of litter discarded in the terrestrial environments. Discarded glass bottles pose multiple ecological risks, including habitat disruption and entrapment of biota (invertebrates and small vertebrates) therefore acting as ecological traps. Particularly, the entrapment of biota in bottles has been investigated in the mainland and on islands. On this latter, the presence of these anthropogenic traps can lead to strong impacts on the populations of some species. Being islands an important site of occurrence of species of biogeographic interest, here, we aimed to investigate the entrapment of small vertebrates by discarded glass bottles recorded in a small Mediterranean island (circum-Sardinia). We collected glass bottles on 15 transects and calculated a density index (Abundance Kilometric Index; AKI, in bottle/km). On 38,810 m sampled, 86 glass bottles were collected (AKI = 2.22): 15 bottles along paved roads (AKI = 1.57) and 71 along pedestrian paths (29,230 m; AKI = 2.43). Differences between frequencies of bottles with organisms between paved roads and terrestrial paths were not significant either on the total of bottles and for large and small ones. In bottles, we recorded both invertebrates (terrestrial Gastropoda mollusks and Insecta Coleoptera indet.) and remnants of small vertebrates (one Mus musculus, one Chalcides ocellatus). Our study found a low density of discarded glass bottles (< 3/km) when compared to an analogous research carried out in neighbouring Sardinia. This low density suggests an ‘insular effect’ acting on animals entrapped by debris, i.e. a reducted rate of entrapment of bottles on small vertebrates. This effect may be driven by both low human presence and low species richness, which limits the risk of small vertebrates being trapped in bottles.

Plastics are a significant environmental problem, accumulating in ecosystems and causing harmful effects. While macroplastics in rivers have only recently gained attention, most studies focus on their transport to the sea, neglecting the fact that plastics often remain within fluvial systems. Previous research has primarily considered abiotic factors in this transport process. However, recent findings indicate that vegetation plays a crucial role in trapping plastics in urban and lowland watercourses. The role and structure of riparian vegetation in plastic entrapment are poorly understood. This study investigates the relationship between vegetation structure and plastic entrapment applying the 3D Vegetation Index (3DVI) to quantify vegetation complexity and its capacity to trap plastics. Field data on plastics and vegetation were collected from six rivers in central Italy across three riverine zones. Results show a significant correlation between macroplastics trapped in vegetation and vegetation structure, with denser and more diverse plant communities trapping more plastics. Particularly, a significant regression between 3DVI and plastics in vegetation was observed only in the lower river zone. The higher the 3DVI value, the more complex the vegetation, indicating greater plastic trapping efficiency. These findings suggest that biotic factors, particularly vegetation structure, are important variables for driving riverine plastic entrapment at local scales. This study is the first to apply a vegetation index to describe the complexity and diversity of plant communities related to plastic entrapment. Future research urgently needs to unveil this phenomenon at a global scale as well as to focus on the interactions and effects of macroplastics on plants. Understanding plant structures and 3DVI usage in retaining plastics can help identify plastic hotspot areas and inform mitigation and clean-up efforts to address plastic pollution effectively.

Plastic pollution is a widespread issue in marine ecosystems worldwide, and at the basin level, the Mediterranean represents one of the main hotspots for plastic debris. Here, we present MPs pollution levels in the bivalve Donax trunculus, commonly known as wedge clam, considering both young and adult individuals, as well as sediment and water matrices across a national scale, covering the Tyrrhenian, Ionian, and Adriatic coasts of Italy. The aim is to provide an overview of MPs pollution in coastal ecosystems and assess whether wedge clams can act as an early warning sentinel for sandy habitats. Results highlighted that the Adriatic and Ionian coasts exhibited higher MPs levels than the Tyrrhenian coast across all matrices, with MPs pollution predominantly consisting of blue acrylic fibers. D. trunculus proved to be an excellent sentinel for MPs pollution in sediment. The findings also revealed that young individuals had more MPs than adults, highlighting potentially severe harm to the growth of marine organisms. As a commercially valuable species, this study underscores the urgent need to further investigate this issue, especially given its critical implications for both marine ecosystem health and human well-being.

Plastic pollution, particularly microplastics (MPs) and nanoplastics (NPs), is increasingly threatening urban aquatic environments. These particles (25-1000 μm) originate from diverse sources and exhibit complex environmental behavior depending on their physicochemical characteristics and interactions with organic matter. Wastewater treatment plants (WWTPs), though designed to mitigate various contaminants, have demonstrated limited efficiency in removing micro and nanoplastics (MNPs), with effluent concentrations ranging from 0.2 to 180 × 10^6 MPs L-1 and removal rates 40-95 % for MPs, and lower for NPs depending on the treatment process and particle properties. This inefficiency contributes to the persistent dissemination of MNPs into rivers, lakes, and coastal areas. Moreover, ecotoxicological evidence, although limited, indicates oxidative stress and physiological impairments in fish, highlighting substantial knowledge gaps. To address these knowledge gaps, recent scientific efforts have focused on understanding the occurrence, sources, and behavior of MNPs across urban water systems, along with assessing the effectiveness of physical separation and chemical/biological degradation technologies. While methods such as coagulation, filtration, adsorption, and advanced oxidation processes show promise, each presents limitations in terms of operational cost, energy demand, and the potential generation of toxic by-products. Emerging strategies such as upcycling plastic waste and employing nature-based solutions (e.g., riparian vegetation restoration, constructed wetlands) offer complementary benefits but require further investigation and investment. This review critically summarizes current knowledge on the sources, fate, ecological impacts, and management strategies of MNPs in urban waters, identifies region-specific challenges and research gaps, and provides guidance for future monitoring, technological innovation, and policy interventions.

Species belonging to the crustacean infraorder Astacoidea represent taxa of particular interest from a conservation point of view, such as the threatened European crayfish (i.e., Austropotamobius pallipes), and at the same time include invasive taxa having highly negative impacts where they are introduced. Among the latter, some freshwater-dwelling species seem to show some abilities to tolerate high salinity levels, such as Procambarus clarkii Girard, 1852. By using metadata and field observation, this review will investigate whether the alien P. clarkii can threaten coastal waters. Specifically, we will shed light on P. clarkii’s (1) invasiveness, (2) its dispersal pattern, (3) its tolerance to salinity, and (4) its ecological plasticity as an invasive species in relation to estuaries. This new habitat colonization is also possible as P. clarkii has been observed to survive up to 20 ppt of water salinity and a maximum of 30–35 ppt with its lifetime drastically reduced. As a result, P. clarkii colonizes different ecosystems globally, reaching estuarine and coastal ecosystems due to active and passive transport by human and animal vectors. Due to recent discoveries of alien crayfish in estuarine and coastal waters, monitoring activities have become mandatory to preserve coastal habitats and all the aquatic resources (e.g., limicolous birds, endemic fish, fishery and aquaculture activities) inhabiting therein.

The increasing production and environmental release of plastics have led to the widespread presence of microplastics (MPs) in diverse ecosystems. Pollinators, such as honeybees (Apis mellifera), are particularly vulnerable to MP exposure due to their foraging behavior, which brings them into contact with contaminated environmental matrices, including air, water, and floral resources. This study aims to investigate the presence, characterization, and potential ecological implications of MPs in honeybees from two distinct regions in T & uuml;rkiye: a polluted urban area and a pristine rural area. Honeybee samples were collected, digested, and analyzed for MP presence using ATR-FTIR spectroscopy. Our findings confirm the presence of MPs in honeybees from both study sites, with a significantly higher concentration in the urban area (p < 0.01). The majority of detected MPs were fibers (76 %), followed by fragments (19 %) and films (5 %). Five polymer types were identified, with polyethylene terephthalate (PET) being the most prevalent. Concerning the health index, 90.5 % of bees were found dead, while 9.5 % were alive. MPs in honeybees suggest potential implications for pollination services and pollinator health. This study highlights the need for further research on the ecological consequences of MP contamination in pollinators and its potential cascading effects on biodiversity and agricultural productivity.

Wood jams, composed of branches, root wads, fine organic matter, and mineral sediments deposited in river channel zones, play several important roles in river ecosystem functioning. Recent studies conducted in mountain rivers in temperate climates showed that wood jams effectively trap macroplastics, which can pose various risks to the organisms inhabiting them. There is no verification of similar effects in mountain rivers in other climates, where riparian vegetation, wood jam characteristics and river hydrological regime can be different. We sampled macroplastics deposited on wood jams and other surfaces within the channel of the small mountainous Mediterranean Aniene river in central Italy. Our results showed that mass of macroplastic debris trapped by wood jams exceeded those trapped by woody vegetation, herbaceous vegetation, and exposed river sediments by factors of 10, 150, and 600, respectively. These results confirm previous observations from temperate mountain rivers, indicating that wood jams act as temporary hotspots for macroplastic accumulation and potential source of its future remobilization along rivers. Based on this similarity in macroplastic-wood jam interaction, we introduced the term "plastic-wood jam" to describe a specific depositional form that links wood jams with plastic debris in plastic-polluted river systems.

Currently, natural and urban ecosystems are affected by different types of atmospheric deposition, which can compromise the balance of the environment. Plastic pollution represents one of the major threats for biota, including lichens. Epiphytic lichens have value as bioindicators of environmental pollution, climate change, and anthropic impacts. In this study, we aim to investigate the lichen bioaccumulation of airborne microplastics along an anthropogenic pollution gradient. We sampled lichens from the Genera Cladonia and Xanthoria to highlight the effectiveness of lichens as tools for passive biomonitoring of microplastics. We chose three sites, a “natural site” in Altipiani di Arcinazzo, a “protected site” in Castelporziano Presidential estate and an “urban site” in the centre of Rome. Overall, we sampled 90 lichens, observed for external plastic entrapment, melt in oxygen peroxide and analysed for plastic entrapment. To validate the method, we calculated recovery rates of microplastics in lichen. Particularly, 253 MPs particles were detected across the 90 lichen samples: 97 % were fibers, and 3 % were fragments. A gradient in the number of microplastic fibers across the sites emerged, with increasing accumulation of microplastics from the natural site (n = 58) to the urban site (n = 116), with a direct relationship between the length and abundance of airborne microplastic fibers. Moreover, we detected the first evidences of airborne mesoplastics entrapped by lichens. On average, the natural site experienced the shortest fibre length and the centre of Rome the longest. No differences in microplastics accumulation emerged from the two genera. Our results indicated that lichens can effectively be used for passive biomonitoring of microplastic deposition. In this scenario, the role of lichens in entrapping microplastics and protecting pristine areas must be investigated. Furthermore, considering the impact that airborne microplastics can have on human health and the effectiveness of lichens as airborne microplastic bioindicators, their use is encouraged.

Anthropogenic litter, such as plastic, is investigated by the global scientific community from various fields employing diverse techniques. The goal is to assess and finally mitigate the pollutants' impacts on the natural environment. Plastic litter can accumulate in different matrices of aquatic and terrestrial ecosystems, impacting both biota and ecosystem functioning. Detection and quantification of macroplastics, and other litter, can be realized by jointly using visual census and remote sensing techniques. The primary objective of this research was to identify the most effective approach for monitoring macroplastic litter in riverine and marine environments through a comprehensive survey based on the experiences of the scientific community. Researchers involved in plastic pollution evaluated four litter occurrence and flux investigation methods (visual census, drone-based surveys, satellite imagery, and GPS/GNSS trackers) through a questionnaire. Traditional visual census and drone deployment were deemed as the most popular approaches among the 46 surveyed researchers, while satellite imagery and GPS/GNSS trackers received lower scores due to limited field validation and short performance ranges, respectively. On a scale from 0 to 5, visual census and drone-based surveys obtained 3.5 and 2.0, respectively, whereas satellite imagery and alternative solutions received scores lower than 1.2. Visual and drone censuses were used in high, medium and low-income countries, while satellite census and GPS/GNSS trackers were mostly used in high-income countries. This work provides an overview of the advantages and drawbacks of litter investigation techniques, contributing i) to the global harmonization of macroplastic litter monitoring and ii) providing a starting point for researchers and water managers approaching this topic. This work supports the selection and design of reliable and cost-effective monitoring approaches to mitigate the ambiguity in macroplastic data collection, contributing to the global harmonization of macroplastic litter monitoring protocols.

Aquatic plants, seagrasses, macrophytes, mangroves, and riparian vegetation are responsible for some of the most important ecosystem services provided on the Earth. Given their role in trapping plastics along rivers, we propose a new ecosystem service of plastic entrapment by global plants. Although research started recently to study vegetation trapping plastics, little is known about the global patterns of plastic retention and remobilization by vegetation through different habitats. Given those gaps, we synthesize global data on plastic entrapment in plants providing a conceptual model to describe processes for plastic retention by vegetation. Our results demonstrate how vegetation has a pivotal role in entrapping plastics across spatial and temporal scales, finding the higher density of plastics on plants rather than in the adjacent water area. Furthermore, we proposed a conceptual model (i.e., Plant Plastic Pathway) of plants entrapping plastics, highlighting spatial and temporal scales of plastic retention and release processes in different habitats. Thus, we anticipate our conceptual model to be a starting point for more sophisticated future studies, putting effort into looking at plastic-vegetation dynamics. Our conceptual model may have a crucial effect if applied to plastic hotspot area detection with clean-up and mitigation actions in riverine ecosystems.

Macroplastic litter causes detrimental effects on freshwater biota affecting human health. Despite the significant role of rivers in transporting plastic waste, most plastics remain in fluvial ecosystems, accumulating in infrastructure, river sediment, and (riverbank) vegetated areas. However, the entrapment of plastics by riparian vegetation was overlooked, particularly in upper and middle river courses. For the first time, we aimed to quantify the entrapment of plastics by riparian vegetation along the entire river course. Sampling riparian areas in the upper, middle, and lower river courses in central Italy, we found 1548 macrolitter items, with vegetation entrapping 93.9% of total litter. Riverbank and riparian plastics acted as long-term indicators of river plastics. We emphasized the trapping efficiency at the species level highlighting that the best plastic trapper species were trees, shrubs and reeds (Populus spp., Salix spp., Rubus ulmifolius, Phragmites australis, and Ficus carica), blocking 85.4% of the total macrolitter entrapped by plants. Plastic pieces, bags, bandages, sanitary items, and packaging were among the most trapped types. Furthermore, vegetation in the lower river course exhibited greater plastic entrapment compared to the upper and middle courses, following the fact that all the river courses contribute to plastic pollution. Recognizing the potential of riparian vegetation as a valuable ecosystem service in trapping macroplastics, further research should explore the characteristics and structures of riparian communities involved in this process. By developing eco-safe practices and mitigation strategies based on these findings, we might contribute significantly to managing, conserving, and restoring riverine ecosystems.