Search Results (192)

Mesozooplankton play a pivotal role in marine pelagic food webs, mediating energy and matter transfer between primary producers and higher trophic levels. Daya Bay, a semi-enclosed bay located in the northern South China Sea, has undergone significant environmental changes due to anthropogenic activities, such as thermal discharge from nuclear power plants and eutrophication. This study examined the mesozooplankton community structure, feeding preferences, and food web organization through four seasonal cruises (May 2022, February 2023, August 2023, and November 2023), employing stable isotope analysis and a Bayesian Isotopic Mixing Model. Results indicate that mesozooplankton abundance and diversity were lower in regions affected by thermal discharge, suggesting a suppressive effect of elevated temperatures. Seasonal shifts in dominant species were observed: Penilia avirostris and Dolioletta gegenbauri dominated the community in spring, while Noctiluca scintillans blooms occurred in summer and winter. Isotopic analysis revealed distinct trophic strategies: copepods exhibited omnivorous habits, whereas cladocerans and tunicates showed stronger herbivorous tendencies. N. scintillans functioned as a high-trophic omnivore, preying on copepod larvae and competing for food resources. Overall, the mesozooplankton community was characterized by an omnivory-dominated trophic network, which enhanced resilience yet remains sensitive to anthropogenic disturbances. This study clarifies how human-induced environmental changes reshape trophic pathways in subtropical coastal waters, providing a valuable reference for long-term monitoring and ecosystem management in Daya Bay. Full article

This study examined the seasonal and size-related variations in the diet composition and feeding strategies of the robust tonguefish Cynoglossus robustus collected in the Yeosu Coast, Korea, from January to December 2024. Stomach content analysis identified amphipods, polychaetes, and brachyurans as the dominant prey items. Ontogenetic dietary shifts were evident, with individuals < 25 cm TL feeding mainly on amphipods, whereas larger individuals consumed more polychaetes and brachyurans, indicating a shift toward larger and more energy-efficient prey with growth. Amphipods, with Ampelisca sp. being predominant, were predominant in spring and summer, whereas crabs and polychaetes increased in autumn and winter, respectively. Seasonal variation was attributed to environmental factors and post-spawning feeding recovery. The estimated trophic level (3.22) suggests that C. robustus functions as a mesopredator consuming benthic invertebrates and plays an essential role in energy transfer within the coastal benthic ecosystem. These findings provide fundamental ecological insights into the trophic structure of the coastal ecosystem in the southern sea of Korea and serve as a scientific basis for sustainable fisheries resource management. Full article

Per- and polyfluoroalkyl substances (PFASs) represent a group of persistent environmental contaminants with known adverse health effects. This study assessed the presence and concentrations of PFASs in surface water across various locations along the Gunpowder River Watershed in Maryland, United States. Gunpowder RIVERKEEPER^® a 501(c)(3) nonprofit collected eleven surface water grab samples from the Gunpowder River Watershed for the study, including both drinking water sources and non-drinking tributaries. Of the 55 PFASs analyzed, multiple compounds, including PFOS, PFOA, PFBS, PFHxA, PFPeA, and PFHpA, were detected above reporting limits at all sampled locations. Total PFAS concentrations varied substantially across the watershed, ranging from 2.1 to 21.3 ng/L in drinking water source tributaries and 6.6–18.4 ng/L in non-drinking tributaries. Several sites exhibited PFOS and PFOA concentrations exceeding the 2022 U.S. EPA interim lifetime health advisory levels, indicating potential risk to downstream communities relying on these water sources. Short-chain PFASs (C ≤ 7) were more abundant than long-chain PFASs, reflecting their greater mobility and persistence in surface waters. These findings demonstrate watershed-wide PFAS contamination and highlight the potential for trophic transfer and bioaccumulation in fish species in these tributaries and subsequent human exposure. Continued monitoring, regulation, and remediation efforts are required to mitigate PFAS contamination and safeguard public health in vulnerable ecosystems and populations. Further research is needed to better understand the extent of PFAS exposure, associated health risks, and effective strategies for prevention and management. Full article

Microplastics are contaminants of increasing environmental concern, particularly in marine ecosystems where they can be easily ingested by marine organisms, causing adverse health problems in animals and, through trophic transfer, in humans. While numerous studies have examined microplastic pollution in marine environments, most focus on water, sediment, or biota, thereby only measuring cumulative effects from multiple pollution sources in one area. This review aims to assess existing research on microplastic pollution originating from shipyards and maritime transport activities, with the goal of identifying current knowledge, methodological approaches, and existing research gaps. A review of the scientific literature was conducted, focusing on studies that investigated microplastic pollution associated with shipyards and maritime transport. Priority was given to peer-reviewed publications that included quantitative or qualitative measurements of microplastics. The reviewed literature reveals a limited number of studies explicitly addressing microplastic emissions from shipyards and maritime transport. Available studies employ diverse sampling strategies and analytical methods, making direct comparisons challenging. This review highlights significant gaps in current knowledge regarding microplastic sources and pathways linked to maritime industries. By synthesizing existing data, the paper provides a foundation for future targeted research and supports the development of more effective pollution reduction strategies. Full article

Eutrophication has emerged as a critical threat to water quality degradation and ecosystem health on a global scale, calling for prompt management actions. Remote sensing enables the monitoring of eutrophication by detected changes in ocean color caused by fluctuations in chlorophyll a (chl a). Although chl a is a crucial indicator of phytoplankton biomass and nutrient overloading, it reflects the outcome of eutrophication rather than its cause. Nutrients, the primary “drivers” of eutrophication, are essential indicators for predicting the potential phytoplankton growth in water bodies, allowing adoption of effective preventive measures. Long-term monitoring of nutrients combined with multiple water quality indicators using remotely sensed data could lead to a more precise assessment of the trophic state. Retrieving non-optically active constituents, such as nutrients and DO, remains challenging due to their weak optical characteristics and low signal-to-noise ratios. This work is an attempt to review the current progress in the retrieval of un-ionized ammonia (NH₃), ammonium (NH₄⁺), ammoniacal nitrogen (AN), nitrite (NO₂⁻), nitrate (NO₃⁻), dissolved inorganic nitrogen (DIN), phosphate (PO₄³⁻), dissolved inorganic phosphorus (DIP), silicate (SiO₂) and dissolved oxygen (DO) using remotely sensed data. Most studies refer to Case II highly nutrient-enriched water bodies. The commonly used spaceborne and airborne sensors, along with the selected spectral bands and band indices, per study area, are presented. There are two main model categories for predicting nutrient and DO concentration: empirical and artificial intelligence (AI). Comparative studies conducted in the same study area have shown that ML and NNs achieve higher prediction accuracy than empirical models under the same sample size. ML models often outperform NNs when training data are limited, as they are less prone to overfitting under small-sample conditions. The incorporation of a wider range of conditions (e.g., different trophic state, seasonality) into model training needs to be tested for model transferability. Full article

Trace metals and metalloids pose persistent threats to freshwater ecosystems, yet their trophic transfer and sublethal effects across food webs remain poorly understood. We investigated bioaccumulation patterns and biomarker responses in a predator–prey system comprising Prussian carp (Carassius gibelio) and Great Cormorant (Phalacrocorax carbo) nestlings from the Danube floodplain wetland Kopački rit Nature Park (Croatia) during 2023–2024. Concentrations of arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg) and lead (Pb) were determined in Prussian carp liver and in Great Cormorant whole blood. The activities of acetylcholinesterase (AChE), carboxylesterase (CES), glutathione S-transferase (GST) and the levels of reactive oxygen species (ROS) and reduced glutathione (GSH) were measured in brain, muscle and gill tissues of Prussian carp, as well as in plasma and S9 blood fractions of Great Cormorants. In addition, tissue-specific metal concentration ratios (TSMCR) were calculated to assess the relative magnitude of recent dietary exposure in the predator compared to the prey. Biomarker activity showed strong tissue- and fraction-specific variation, with temporal differences. Exposure–response modelling revealed significant associations between As, Cd, and Hg and specific biomarkers, particularly in gill and plasma. Cross-species comparisons indicated elevated TSMCR as a proxy for recent trophic exposure only for Hg in 2023, whereas As and Se exhibited lower TSMCR. These findings demonstrate that metal exposure in floodplain systems induces physiological responses and Hg poses the greatest prey-to-predator exposure risk, highlighting the value of integrating pollutant measurements with mechanistic biomarker endpoints to evaluate ecosystem-level impacts. Full article

Microplastics (<5 mm) have become a pervasive pollutant because of their persistence, bioavailability, and risk of trophic transfer. The present work provides new evidence on microplastic contamination in three economically important species from the Romanian Black Sea coast: Mytilus galloprovincialis, Rapana venosa, and Sprattus sprattus. Microplastics were extracted using 10% potassium hydroxide (KOH) chemical digestion and examined under a stereomicroscope. Microplastics frequency of occurrence (FO%) ranged from 66.7% to 93.3%, with mean abundances per individual being 3.06 ± 3.71 in mussels, 3.26 ± 2.08 in rapa whelks, and 3.13 ± 2.44 in sprats. Fibers were the dominant type, followed by fragments, with blue, black, and transparent colours most common. Most particles were within the 1–5 mm and 330 µm⁻¹ mm size classes, with smaller fractions between 100 and 330 µm, indicating ingestion of particles large enough to accumulate rather than be rapidly egested. The microplastic contamination found in predatory R. venosa suggests trophic transfer of microplastics from bivalve prey. As all three species are consumed by humans, they represent potential pathways for microplastic exposure. These results emphasize the urgent necessity for additional research on sources, environmental pathways, and possible health risks of microplastics in the Black Sea. Full article

Nanoplastics are ubiquitous in aquatic environments, and elucidating their bioaccumulation behavior is essential for assessing toxicity and trophic transfer risks. While most studies focus on nanoplastics properties (e.g., type, size, surface charge), the influence of organismal growth stage remains unclear. Through bioaccumulation kinetic experiments with 10 mg/L polystyrene nanoplastics (PSNPs), this study found that Tetrahymena thermophila (T. thermophila) in the lag phase (cell density 4 × 10⁴ cells/mL) exhibited the highest uptake rate of nanoplastics, 1.2–5.8 times that of the exponential phase (1–5 × 10⁵ cells/mL) and 7.7 times that of the stationary phase (>5 × 10⁵ cells/mL). Lag phase cells also had a larger specific surface area (0.319 vs. 0.271/0.269 μm⁻¹), supporting their heightened uptake capacity. Under PSNP exposure, exponential and stationary phase cells showed significantly elevated reactive oxygen species (ROS) levels, accompanied by downregulated superoxide dismutase (SOD) and stable catalase (CAT) activity, indicating impaired antioxidant defense and potential redirection of energy toward stress mitigation. Consistent with efficient internalization, confocal imaging revealed clear PSNP colocalization within food vacuoles of lag period cells. Proteomic and transcriptomic analysis further confirmed the upregulation of carrier proteins, FAD/FMN oxidoreductases, and pathways associated with cellular components (membrane and organelle membrane) and molecular functions (transporter activity and transmembrane transporter activity) in lag-phase T. thermophila. Collectively, these findings provide a molecular-level understanding of the multi-phase-dependent bioaccumulation of PSNPs, offering critical insights for assessing the environmental risks of polystyrene nanoplastics in dynamic aquatic ecosystems. Full article

The pervasive environmental contamination by microplastics (MPs) and per- and polyfluoroalkyl substances (PFAS) represents a critical challenge of the Anthropocene. While historically studied in isolation, a growing body of evidence confirms that these pollutants interact to form a complex and dynamic MP-PFAS Nexus. This review synthesizes current knowledge to elucidate the multifaceted mechanisms of this interaction, where MPs act as vectors, concentrators, and secondary sources for PFAS. We detail how environmental aging and water chemistry modulate adsorption and transport, fundamentally altering the fate of both contaminants. Crucially, the review consolidates evidence demonstrating that co-exposure often leads to synergistic toxicity, disrupting physiological processes from photosynthesis in algae to lipid metabolism and neurogenesis in animals, with significant implications for trophic transfer. The nexus also presents formidable challenges for water treatment and soil remediation, while simultaneously offering opportunities for targeted destructive technologies like pyrolysis. Furthermore, we explore the emerging threats of this complex to human health via seafood and water, and the amplifying feedback of climate change. Finally, we argue that current regulatory frameworks, which assess pollutants individually, are inadequate and must evolve to account for combined effects. This review underscores the imperative to reframe MPs and PFAS as an interconnected pollutant system, necessitating integrated research and policy for effective environmental risk assessment and management. Full article

Mining activities have led to contamination of natural resources by heavy metals (HMs). Biomagnification studies of HMs within food webs are necessary for understanding the progressive increase in metal burdens across trophic levels and their potential ecotoxicological consequences. This study examined the trophic transfer of Cd, Cu, Pb, and Zn in a tri-trophic model involving maize plants (Zea mays), their herbivore, the grasshopper Sphenarium purpurascens, and their predator, the spider Neoscona oaxacensis, under controlled conditions. Samples from all individuals were collected in Huautla, Morelos, Mexico, where three tailing deposits are present, containing approximately 780,000 tons of waste rich in HMs. We evaluated the body biomass of the grasshopper and the percentage of maize leaf material consumed with and without HMs. HM bioaccumulation in maize, grasshopper, and spider tissues was analyzed, and the enrichment process, along with gender related effects on HM bioaccumulation in females and males of S. purpurascens, was studied. The results revealed enrichment of Pb, Cd, and Cu in maize leaf tissue, except for Zn. Grasshoppers exhibited biomagnification of the same metals, except for Cd. Metal bioaccumulation resulted in a reduced biomass of female and male grasshoppers, accompanied by an increased leaf consumption compared to grasshoppers fed maize leaves without HMs. The HMs’ bioaccumulation levels differed between genders, with males recording significantly higher concentrations of Zn and Pb. The excretion of HMs in feces and their bioaccumulation in exoskeletons are two efficient metal detoxification strategies in grasshoppers. This study revealed biomagnification in the spider N. oaxacensis, confirming metal biomagnification to higher trophic levels and providing critical insight into exposure pathways, risks to wildlife and humans, and how metal pollutants may disrupt ecosystem integrity. Full article

Nanoplastics, due to their small size and high surface reactivity, have emerged as critical pollutants with potential impacts on both environmental and biological systems. Their capacity for cellular internalization, bioaccumulation, and trophic transfer raises serious concerns for ecosystem and human health. The objective of this study is to conduct a comprehensive bibliometric assessment of global research trends pertaining to biological endpoints such as the uptake, cell internalization, and bioaccumulation of nanoplastics. Using the Scopus database and VOSviewer software (version 1.6.20), 638 relevant scientific articles published between 2012 and 2024 were analyzed. The number of publications has grown significantly in recent years, particularly from 2020 onward, indicating increasing scientific attention. Co-authorship among authors and among countries analyses highlights the global and interdisciplinary nature of this field, with strong contributions from China, Europe, and the United States. Keyword co-occurrence analysis reveals a strong thematic focus on oxidative stress, genotoxicity, and the interaction of nanoplastics with heavy metals, suggesting emerging interest in combined toxicity effects. Citation analysis of journals confirms that leading publications in environmental science and toxicology have been central to the dissemination of key findings. The results emphasize a growing international commitment to understanding the behavior of nanoplastics in biological systems, particularly their accumulation and potential health risks. This analysis not only maps the evolution of research but also identifies gaps of knowledge and future directions, offering a foundation for guiding subsequent investigations and informing regulatory frameworks. The use of software tools such as VOSviewer (version 1.6.20) is essential for synthesizing large volumes of scientific data, reducing subjectivity, and, thus, providing visual insights into the structure and development of this research field. Full article

The Danjiangkou Reservoir (DJKR) serves as the water source for the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP), yet comprehensive understanding of its ecosystem structure and function remains limited. This study addressed this knowledge limitation by developing an Ecopath model with 22 functional groups, parameterized using field survey data from 2022 to 2023. Our findings revealed a trophic structure spanning levels 1 to 3.59, with the highest level occupied by piscivorous mandarin fish (Siniperca spp.). Energy flowed through two dominant pathways, with the grazing food chain demonstrating higher transfer efficiency compared to the detrital pathway. Mixed trophic impact analysis identified the introduced icefish (Neosalanx taihuensis) as exerting substantial negative impacts on most functional groups. Key ecosystem indices, including the total primary production to total respiration ratio (TPP/TR, 1.99), connectance index (CI, 0.248), and system omnivory index (SOI, 0.113), collectively indicated an ecosystem of moderate maturity and stability. Persistent challenges include the proliferation of N. taihuensis, suboptimal energy transfer between trophic levels III and IV, and inefficient utilization of primary productivity. To enhance ecosystem resilience and maintain water quality, we recommend the targeted removal of icefish and strategic management of zooplanktivorous fish populations. Full article

Nanoplastics have emerged as widespread environmental contaminants with toxicological properties that differ from those of microplastics. While existing reviews often examine their effects on specific organisms, they rarely provide direct comparisons with microplastics. This review aims to comprehensively assess the toxic effects of nanoplastics on animals, with a comparative perspective highlighting their distinctions from microplastics. In mammals, nanoplastics cross the blood–brain barrier and induce oxidative stress, neuroinflammation, mitochondrial dysfunction, and synaptic disruption, with consequences ranging from cognitive impairment to Parkinson’s disease-like neurodegeneration. They also impair liver, kidney, intestinal, pancreatic, and reproductive function, with evidence of transgenerational toxicity. In aquatic organisms such as fish, crustaceans, bivalves, and aquatic invertebrates, nanoplastics compromise growth, immunity, reproduction, and metabolism, while in terrestrial invertebrates they cause gut toxicity, mitochondrial damage, immune suppression, and heritable defects. Across taxa, the dominant mechanisms involve oxidative stress, apoptosis, inflammation, and interference with metabolic and signaling pathways. Comparisons with microplastics reveal that while both particle types are harmful, nanoplastics generally exert stronger and more systemic effects due to higher bioavailability, cellular uptake, and molecular reactivity. Microplastics primarily impose mechanical stress, whereas nanoplastics disrupt cellular homeostasis at lower exposure levels, often acting at the subcellular level. Evidence also indicates size-, surface chemistry-, and concentration-dependent effects, with smaller and functionalized nanoplastics exhibiting heightened toxicity. Despite growing knowledge, significant gaps remain in cross-size comparative studies, long-term and multigenerational assessments, trophic transfer analyses, and investigations involving environmentally derived nanoplastics. Addressing these gaps is critical for advancing ecological risk assessment and developing mitigation strategies against plastic pollution. Full article

Freshwater ecosystems face increasing contamination by heavy metals, yet their transfer patterns remain poorly understood. This study aimed to assess the extent of pollution by ten potential toxic elements (As, Ni, Zn, Pb, Cd, Cr, Fe, Cu, Mn and Se) in water, sediment, Spirogyra sp., and two endemic fish species (Tropidophoxinellus callensis and Luciobarbus callensis) in the El Mellah River. The element concentrations were measured in four matrices using inductively coupled plasma optical emission spectrometry. Bioaccumulation Factor and Trophic Transfer Factor were used to depict bioaccumulation patterns across the ecological strata and two levels of the food web. The results showed that all sediment samples demonstrated very high ecological risk, consistently exceeding critical thresholds (PLI > 1, RI > 600). Contamination factor and geoaccumulation index revealed moderate to extreme contamination by As and Cd throughout all samples. Both fish species exhibited a bio-accumulation affinity for Cr, Cd, Mn, and Zn from water, while concurrently accumulating As from Spirogyra sp. Muscle tissue concentrations of As, Pb, Cr, and Cd in both species exceeded international guideline values. Health risk assessment indicated that children face elevated exposure risks, with Cd intake exceeding safe limits and total hazard quotient surpassing safety thresholds by 2.6-fold, while carcinogenic risks from Cd and Cr exceeded acceptable levels for both adults and children. These findings provide baseline contamination data for this tributary system and highlight elevated risks to both human health (through fish consumption) and ecosystem integrity, indicating the need for targeted monitoring and risk management measures. Full article

The dynamic behavior and biologically mediated transformation of microplastics (MPs) in crustaceans remain insufficiently explored in aquatic ecotoxicology. In this study, we employed the red swamp crayfish (Procambarus clarkii) as a model organism to systematically investigate the accumulation, distribution, fragmentation, and excretion kinetics of MPs within its digestive system under controlled conditions. We exposed crayfish to fluorescent polystyrene microplastics (50 μm) at a high concentration (100,000 particles/L), which exceeded typical environmental levels but was necessary to track accumulation and fragmentation dynamics within the experimental timeframe, and dissections were performed at 24, 48, and 96 h. Spatiotemporal patterns and morphological changes in MPs were analyzed using advanced microscopic imaging techniques. The results revealed a peak in MP accumulation at 48 h, followed by a decrease at 96 h, suggesting a dynamic equilibrium between ingestion and elimination. Over time, particle sizes decreased significantly, a result consistent with microplastic fragmentation. Additionally, feed supplementation during depuration was associated with increased fragmentation efficiency. Morphological analysis showed digestion-induced changes such as surface wrinkling, irregular edges, and particle shrinkage. These findings elucidate the transformation mechanisms of microplastics within crustaceans and provide crucial insights for assessing their potential ecological risks and fate as pollutants. Based on results from high-concentration short-term laboratory exposure studies, this paper further indicates the necessity for in-depth exploration into the long-term dynamics of microplastics within aquatic organisms and the potential for their transfer across trophic levels. Full article