Search Results (277)

Climate change models point to a possible rise in air temperature, ranging from 2 °C to 4 °C. Global changes will therefore have a particularly pronounced effect on the functioning of shallow water bodies known as peat ponds, i.e., habitats formed after peat extraction in peatlands. However, the extent of this impact is still unknown. The main objective of the study was to determine the impact of water level and water physicochemical properties on the functioning of selected groups of aquatic organisms in peat ponds of different origins. The study was conducted in spring, summer and autumn of the years 2024 and 2025, in 10 peat ponds with different trophic status and typology, located in the Polesie National Park in eastern Poland. Considerable fluctuations in water levels, resulting from a scarcity of precipitation, accelerated the drying out and overgrowth of peat ponds, particularly the alkaline and acidic types. Within the zoocoenotic communities, a significant decline in the abundance of planktonic species and an increase in the abundance of littoral or periphytic species were recorded (F = 6.24, p < 0.015). Regarding trophic structure, an increase in the abundance of mixotrophic species and a decrease in the abundance of top-level predators were observed. Hydrological changes were reflected in an increase in species richness and abundance of communities of organisms with broad ecological tolerance (mainly ciliates), and a decrease in the number of species and abundance of planktonic crustaceans and macroinvertebrates. The RDA model explains over 84% of the total variability, indicating excellent model fit to the data and a strong correlation between environmental variables and species composition. Based on p values, water level, temperature, pH, and COD were selected as significant variables, with conductivity, O₂, and P_tot demonstrating less statistical significance. Peat ponds ecosystems can serve as an excellent model system for studying the impact of intensifying climate change on the functioning of shallow water bodies. Full article

Microplastics, plastic particles smaller than 5 mm, are significant pollutants of growing global concern due to their persistence, widespread distribution, and potential ecological and human health risk. Numerous studies have proposed different methods for sampling microplastics in river sediments and water. However, comparative studies evaluating how different sampling methods affect the quantification of microplastic abundance in surface water remain limited. This study focused specifically on surface water, as it represents the primary pathway of microplastic transport, and the yield is most directly influenced by sampling method selection. Therefore, this study aimed to compare the abundance and characteristics of microplastics collected using three sampling methods: plankton nets, buckets, and pumps, which were selected to represent the full spectrum of commonly used riverine surface water collection approaches. Each method collected an equivalent volume of water, 1000 L. Statistical analysis showed no significant differences among the methods in terms of microplastic abundance and characteristics. These results suggest that the selection of a sampling method should be primarily based on river characteristics such as flow velocity, depth, and channel width rather than methodological differences. The findings provide practical guidance for selecting appropriate sampling approaches in low-flow river environments. Full article

The water bodies of southern Kazakhstan are under strong anthropogenic pressure, underscoring the relevance of their comprehensive research. In the summer of 2025, hydrobiological and hydrochemical studies were conducted at 32 stations across seven water bodies in the region. The dissolved solids content (TDS) ranged from 239.5 to 1472.5 mg/dm³, with favorable oxygen levels and relatively low nutrient levels. Zooplankton comprised 100 species, with rotifers predominating. Zooplankton abundance was 133.2–1289.9 thousand specimens/m³, with a biomass of 0.99–3.94 g/m³. The average number of species per sample varied from 11.5 to 26.7. The Shannon index values ranged from 1.20 to 2.74 bits. The average individual mass of a specimen varied from 0.0011 to 0.0371 mg. Cluster analysis revealed significant differences in the species composition of planktonic invertebrates across water bodies and their biotopes, which, according to the MDS analysis, reflected heterogeneity in external conditions. Analysis of multivariate data showed that the main factors shaping summer zooplankton community structure in the surveyed water bodies were TDS, silicon, and phosphate. The reasons for the identified dependencies between abiotic and biological variables are discussed. The high indicator significance of zooplankton communities in assessing the ecological state of aquatic ecosystems is demonstrated. Full article

Mesozooplankton were studied monthly (September 2023–August 2024, 12 months) at two coastal stations, at 35 and 90 m water depth, off Punta Blanca, SW Tenerife, Canary archipelago. Sample collection involved 250 and 500 μm bongo nets. This research focused on improving the description of plankton biodiversity and dynamics of the Canary archipelago (Macaronesia area), including its role in the transport of particulate carbon. A total of 156 taxa were identified. Copepoda dominated with 85 taxa, including 72 Calanoida species. They were numerically followed by Appendicularia, Chaetognatha, and Hydrozoa. Mesh sizes varied in collection efficiency, but with a similar pattern during the annual cycle: abundance peaks in early autumn (October–November) and late winter–spring (February–April). The 35 m depth station showed 57 to 3809 ind. m⁻³ (250 μm mesh size) and 10 to 1577 ind. m⁻³ (500 μm). The 90 m depth station showed 22 to 402 ind. m⁻³ (250 μm) and 11 to 170 ind. m⁻³ (500 μm). The present study enhances our understanding of Macaronesia’s mesozooplankton dynamics related to environmental variability, which is crucial for energy transfer assessments in pelagic food webs. It reports new species for the study area, Labidocera acutifrons (Dana, 1849–1852) and Undinula vulgaris (Dana, 1849–1852), highlighting the need for consistent zooplankton monitoring to properly inform conservation and sustainable management actions in the region. Full article

Introduction: The early stages of fish represent a critical phase for survival and recruitment, as they are highly vulnerable to both biotic and abiotic factors, as well as anthropogenic pressures. To enhance survival, many marine species use estuaries as nursery areas. However, these ecosystems are increasingly exposed to contaminants such as microplastics (MPs; plastic particles < 5 mm) that can cause several direct or indirect negative impacts on fish larvae, namely impairing their development or survival. Objective: This study aimed to quantify and compare temporal changes in the ratio of microplastics (MPs) to fish larvae (FL) (MP:FL) in the Douro estuary (NW Portugal), assessing how exposure to MPs varies across years and seasons. Methodology: Seasonal sampling campaigns were conducted in the Douro estuary during 2021/2022 and 2025. Multiple stations along the estuary were sampled using plankton tows with a 0.5 mm mesh size. In the laboratory, fish larvae were sorted and identified, and the remaining material was processed to isolate and quantify MPs. The recovered MPs were subsequently characterized according to type, size, and color. Results: Data from 2022 indicated that Clupeidae, Gobiidae, and Gadidae were the most abundant fish families, while colorless and blue fibers between 2 and 3 mm were the dominant MP types. Data from 2025 showed that Gobiidae, Labridae, and Atherinidae were the most abundant families, with similar MP types observed in water in 2022. The ratio of MPs:FL in summer and autumn of 2021/2022 was 36 and 65 MPs:1 FL, respectively, whereas in 2025 it was 0.26 and 3.80 MPs:1 FL, respectively. Conclusions: These preliminary results indicate a decreasing trend in the ratio of MP:fish larvae over time. Although further data analysis is ongoing, the observed interannual differences highlight the importance of long-term monitoring of estuarine nursery areas to better understand contamination dynamics and their potential effects on early fish life stages. Full article

Essential amino acids and unsaturated fatty acids are key nutritional indicators. The human body preferentially absorbs these compounds, which have beneficial effects on health. In aquatic ecosystems, plankton communities serve as the primary food source for aquatic organisms, playing a crucial role in shaping their nutritional composition. In this study, we collected populations of Macrobrachium nipponense and corresponding water samples from ten distinct geographical locations across China. These sites included five freshwater resources and five saline–alkaline water resources. This study measured the ionic composition and plankton community structure of water samples, and analyzed the nutritional components of M. nipponense, aiming to identify indicator taxa linked to the nutritional value in this species. The results show significant differences in both nutritional components and plankton community structures between freshwater and saline–alkaline environments. This suggests a correlation between specific plankton taxa and the nutritional value of M. nipponense. Using relative sequence abundance data from metabarcoding, linear discriminant analysis effect size (LEfSe) analysis identified six plankton indicator taxa at the genus level. Their abundance differed significantly between the two habitat types. The saline–alkaline region had three associated taxa: Cyclotella, Brachionus, and Chaetoceros. In contrast, Arctodiaptomus, Cryptomonas, and Limnoithona were identified as indicator taxa for freshwater regions. Redundancy analysis (RDA) and Pearson correlation analysis revealed that, with the exception of the SY site, the abundance of Chaetoceros and Brachionus in saline–alkaline waters tracked with levels of K⁺, Ca²⁺, and HCO₃⁻. Meanwhile, at the SZ site, plankton community richness rose with CO₃²⁻. Furthermore, the potential correlations between plankton indicator taxa and the formation of specific nutritional components in M. nipponense were explored. These findings highlight the complex interactions among ionic composition, plankton indicator taxa, and nutritional value in M. nipponense. Ultimately, this study can support the development of artificial techniques to regulate the nutritional components of this commercially important species. Full article

The food-packaging sector is undergoing a major transition driven by the environmental burden associated with petroleum-based plastics and the increasing demand for sustainable alternatives. In this context, biodegradable packaging materials capable of extending food shelf life through active preservation functions have attracted considerable interest. Cellulose is the most abundant natural polymer and an attractive candidate for sustainable packaging; however, it lacks intrinsic antimicrobial activity. In the present study, innovative carboxymethyl cellulose (CMC)-based composite films were developed by incorporating zinc oxide (ZnO) nanoparticles (NPs) and thyme essential oil (TEO) as antibacterial active agents. The obtained films exhibited strong antibacterial activity against both Escherichia coli and Staphylococcus aureus, completely eliminating planktonic cell viability after 3 h of contact and producing inhibition zones of up to 30 mm. In addition to their biological performance, the composite films showed improved mechanical and functional properties. ZnO NPs appear to act as multifunctional junctions within the CMC matrix, while the dispersed TEO droplets contribute, together with the inorganic phase, to reduced water-vapor transfer. The films retained good transparency in the visible range while exhibiting UV-A transmittance below 7%, indicating enhanced light-barrier performance. Preliminary tests on soft cheese indicated shelf-life extension up to 14 days at 4 °C, while in inoculated cheese slices packed in the composite films, S. aureus was not detected from the 3rd day. Overall, these results demonstrate the potential of CMC/ZnO/TEO composite films as biodegradable active packaging materials for perishable food products. Full article

The development of effective source rocks is key to hydrocarbon accumulation. The Jinshan Rift Trough, located in the Ordos Basin, is generally considered to be a favorable zone for the formation of source rocks in the Mesoproterozoic Changcheng System. This study investigates mudstones of the Cuizhuang Formation (Changcheng System) from Well PT1 using petrological and geochemical methods to evaluate source rock potential and organic matter enrichment mechanisms. The results show that the original total organic carbon (TOC) and original S₁ + S₂ of the mudstone in the Cuizhuang Formation are 0.06–1.97% and 0.61–10.34 mg/g, respectively, and “good source rock” with a cumulative thickness of 6.7 m is developed in the lower part of the Cuizhuang Formation. The main hydrocarbon-forming organisms of the source rock are planktonic and benthic algae, among which planktonic algae account for a relatively high proportion. Equivalent vitrinite reflectance (R_o) exceeds 2%, indicating an over-mature stage. The TOC of the mudstone of the Cuizhuang Formation shows a weak relationship with the salinity and redox conditions of sedimentary water but has a significant correlation with the paleoproductivity and paleoclimate. Rather than anoxia or salinity, high productivity is the main controlling factor for the enrichment of organic matter in the Changcheng System. Under a warm–humid climate, increased surface runoff and terrestrial nutrient input promote the proliferation of bacteria and algae, leading to the formation and preservation of abundant sedimentary organic matter that forms “good source rocks”. This study provides a theoretical basis for the study of the petroleum system and oil and gas exploration in the Mesoproterozoic Changcheng System in the Ordos Basin. Full article

Coastal port ecosystems serve as critical interfaces between marine environments and anthropogenic activities, yet zooplankton community dynamics in these transitional zones remain poorly understood. This study investigated seasonal variations in zooplankton assemblages and their environmental drivers in the coastal waters surrounding Lanshan Port, northern Yellow Sea, through quarterly field surveys spanning spring to winter. A total of 33 zooplankton species and 16 planktonic larval categories were identified, with Hydromedusa, Copepoda, and planktonic larvae comprising the three dominant groups. Marked seasonal disparities were observed in species richness (spring: 21 species and 11 larvae categories; winter: 8 species and 3 larvae categories), biomass (autumn: 333.7 mg/m³; winter: 34.0 mg/m³), and abundance (spring: 185.3 ind/m³; winter: 25.7 ind/m³). Notably, Aidanosagitta crassa maintained perennial dominance across all seasons. Principal component analysis of dominant zooplankton taxa across seasons indicated that the first two principal components explained 70.05% and 15.97% of the total variance in zooplankton community structure, respectively, with distinct seasonal clustering of sampling sites along PC1 reflecting pronounced seasonal succession in community composition. Redundancy analysis revealed seasonal-specific correlations between dominant taxa and nutrients: nitrate concentration was negatively correlated with the relative abundance of Sergestidae in both spring and summer, whereas ammonium concentration was negatively correlated with Hydromedusa; by contrast, the abundances of Chaetognatha and Tunicata exhibited a significant positive correlation with nitrate. We also found water temperature only drove communities in autumn, while salinity had little effect. These findings elucidate the mechanisms structuring zooplankton communities in temperate coastal port ecosystems and underscore the necessity of seasonally resolved monitoring frameworks for effective marine environmental management. Full article

Deposit-feeding aquatic oligochaete worms are abundant and widely distributed benthic animals in lakes that affect the nutrient cycling between sediments and the water and thus the water quality. This effect can be density-dependent and affected by the presence of filter-feeding bivalves, which can modulate the worms’ impact. We conducted a mesocosm experiment with high, medium, and low densities of the tubificid worms Limnodrilus hoffmeisteri (Oligocheata, Tubificida, and Naididae) in the presence of the filter-feeding bivalve Hyriopsis cumingii. In the low-density treatment, the concentrations of nitrate nitrogen (NO₃⁻-N), ammonium nitrogen (NH₄⁺-N), and organic suspended solids (OSSs) increased moderately compared with the control. In the medium- and high-density treatments, there were also increases in total nitrogen (TN), total phosphorus (TP), soluble reactive phosphorus (SRP), total suspended solid (TSS) and inorganic suspended solid (ISS) concentrations. Moreover, the biomass of phytoplankton (Chl a), the light attenuation coefficients, and the abundance of both cladoceran and rotifer zooplankton rose with increasing worm densities. Water quality deteriorated in both the medium and high worm density treatments, likely due to increased nutrient leading to an increase in the biomass of phytoplankton in our mesocosms, even though plankton-consuming bivalves were present. Thus, during the restoration of eutrophic shallow lakes with a high density of worms, more bivalves are needed to compensate for the negative impact of worms on water quality. Full article

Haptophytes are ubiquitous single-celled eukaryotic plankton in coastal and open oceans that play a key role in marine biogeochemical cycling. Understanding the size structure and community composition of active haptophytes is crucial for elucidating their diversity and ecological functions. This study investigated the diversity and community structure of pico- (0.2–3 μm) and nano-sized (3–20 μm) haptophytes in the surface waters of the western Pacific Ocean using high-throughput sequencing targeting the hypervariable V4 region of the 18S rRNA. The pico-sized community exhibited significantly higher diversity than the nano-sized community. Community composition varied significantly between size fractions, driven primarily by the genera Chrysochromulina and Syracosphaera. Furthermore, the nano-sized community was more strongly influenced by environmental variables than the pico-sized community, although neither size fraction displayed a clear coastal-to-open-ocean distribution pattern. Null and neutral community model analyses indicated that both size-fractionated communities were primarily regulated by stochastic processes, while deterministic processes exerted a greater influence on the nano-sized community. Co-occurrence network analysis revealed stronger interconnections and a higher number of keystone species within the nano-sized community. In both networks, intermediate taxa (relative abundances of 0.01% to 0.1%) exhibited the highest diversity and abundance among keystone species, highlighting their pivotal role in shaping the network structure and stability. Additionally, phylogenetic analyses revealed that while the majority of ZOTUs clustered with known taxa, multiple deep-branching, uncultured lineages were identified across both size fractions, indicating substantial uncharacterized genetic diversity. This study underscores the variability and hidden diversity of size-fractionated haptophyte community structures in oligotrophic open oceans, providing valuable insights into their functional significance in global biogeochemical cycles. Full article

Zelenci is a limnocrene spring in the South-Eastern Alps, attractive for its unique structure and known among researchers for its high diatom diversity. Our aim was to assess how abiotic factors influence the structure of diatom communities in different habitats and to compare the trophic status over 10 years of investigation. Four sampling sites were chosen: two for tychoplankton and two for epipelon. Achnanthidium minutissimum was the most abundant species in both habitats, while Navicula was the most diverse genus (17 species). Planktonic diatoms dominated plankton samples, while the motile ecological type dominated the epipelon. Of all diatom taxa, 23.5% had some endangerment status. Key factors influencing the Shannon–Wiener diversity index were water level, temperature, and concentration of NH₄⁺. The most important abiotic factors for the tychoplankton community were temperature and NH₄⁺, while the most important abiotic factors influencing the structure of epipelon communities were water level, NH₄⁺, pH, and dissolved oxygen concentration. Trophic index revealed increasing inflow of nutrients to the spring; 10 years ago, they were oligotrophic to oligo-mesotrophic, whereas in the present, they are predominantly eu-mesotrophic to eutrophic, indicating human pressure from the catchment area. Full article

Urban water bodies serve as biodiversity hot spots in a human-influenced landscape. We studied the backwater “Alte Donau” (Vienna, Austria), which has been the subject of ongoing management and restoration efforts. We aimed to capture short-term variations in the planktonic and benthic algal community during a vegetation period with a specific focus on Gloeotaenium loitlesbergerianum with its primary distribution in tropical regions. In total, 196 algal taxa were identified, indicating a high and balanced species diversity. Although the waterbody is shallow and densely colonized by macrophytes, phytoplankton and microphytobenthos exhibited significant differences in composition, particularly in spring. Less pronounced differences during summer were probably caused by macrophyte harvesting combined with recreational activities. We found a clear seasonal pattern with spring characterized by blooms of Ochrophyta, followed by a shift towards green algae, Dinophyta, and Cyanobacteria during summer and autumn. We found high variability in spring samples, whereas summer and autumn samples showed increasing similarity. Temperature, silicate, and alkalinity were the primary environmental factors structuring algal community composition. G. loitlesbergerianum was detected during warmer months from May through October across a temperature range of 14 to 28 °C, with highest abundances >20 °C. Warmer water and altered nutrient regimes not only stress native populations but also promote the establishment of new species such as G. loitlesbergerianum, accelerating community shifts. Therefore, sustained monitoring, targeted macrophyte restoration, and effective nutrient management are crucial for preserving both water quality and biodiversity in such systems. Full article

Late Permian paleoenvironmental instability and recurrent biotic crises coincided with enhanced marine organic-carbon burial, yet ocean-circulation dynamics have remained underappreciated as a key driver. In particular, for the Wuchiaping Formation along the eastern margin of the Paleo-Tethys Ocean, the presence, variability, and mechanistic impact of upwelling—and its coupling with water-column redox structures—have not been systematically constrained, limiting a process-based understanding of organic-matter enrichment. Here, we integrate sedimentological, mineralogical, and multi-proxy geochemical data to investigate the dominant controls on organic matter enrichment in the Wuchiaping Formation shale succession from the northeastern Sichuan Basin. The Lower Wuchiaping Formation consists mainly of clay-rich shales deposited under oxic, shallow-water, and weakly stratified conditions, as indicated by low Ni/Co ratios (average 1.88), limited uranium enrichment (U_EF = 0.21), low Ba/Al ratios, and sparse biogenic debris. Biomarker indices (gammacerane index = 0.35; Pr/Ph = 1.91) suggest unfavorable preservation conditions, resulting in a low mean TOC of 0.78%. In contrast, the Upper Wuchiaping Formation is dominated by siliceous shales with elevated Ni/Co ratios (average 15.83), moderate uranium enrichment (U_EF = 2.48), abundant framboidal pyrite, radiolarian–planktic foraminiferal assemblages, and laminated apatite. High Ba/Al and Cd/Mo ratios, higher gammacerane values, and low Pr/Ph ratios (<1) indicate enhanced water-column stratification and bottom-water anoxia, leading to efficient organic matter preservation and a high mean TOC of 9.2%. Biomarker compositions reveal a shift from terrestrial-dominated organic matter in the Lower Wuchiaping Formation to algal- and plankton-derived inputs in the Upper Wuchiaping Formation. Collectively, these results indicate that intensified upwelling—rather than tectono-magmatic forcing alone—was the primary driver of enhanced productivity, strengthened redox stratification, and organic matter enrichment in the Upper Wuchiaping Formation. Our findings highlight the importance of upwelling–redox coupling as a key mechanism linking Late Permian ocean-system reorganization to spatially and stratigraphically heterogeneous organic-carbon accumulation along the Paleo-Tethyan margin. Full article

The second member of the Kongdian Formation (Ek₂; also referred to as the Kong 2 Member) in the Cangdong Sag within the Bohai Bay Basin contains a series of high-quality lacustrine shales characterized by high organic matter abundance and significant hydrocarbon shows. However, the mechanisms governing organic matter enrichment in the deep parts of the sag remain poorly understood, and the impacts of depositional environments on organic matter enrichment are yet to be determined. This study investigated shales in the C1, C3, and C5 sublayers of the Kong 2 Member. Specifically, this study examined the mineralogy and petrology, organic geochemistry, and elemental geochemistry of the shales using whole-rock X-ray diffraction (XRD) analysis, total organic carbon (TOC) analysis, pyrolysis experiments, and analyses of macerals, major and trace elements, and stable carbon and oxygen isotopes. Additionally, numerical analyses were conducted. The results indicate that shales in the Kong 2 Member consist primarily of felsic, dolomitic–calcareous, and mixed shales. These shales exhibit high TOC content (average: 3.07%), and favorable organic matter types dominated by liptinite and interbedded with minor planktonic algae and amorphous sapropelinite. These suggest great potential for hydrocarbon exploitation. During the deposition of shales in the Kong 2 Member, substantial terrigenous clasts were deposited at moderate rates under relatively arid climates characterized by frequently alternating dry and humid conditions. In this period, the anoxic to reducing depositional water bodies showed elevated salinity, resulting in saline-to-brackish water environments and moderate paleoproductivity. The organic matter enrichment of shales in the Kong 2 Member was jointly governed by paleoclimate dynamics, terrigenous input, and redox conditions, as demonstrated by multivariate analyses including the correlation analysis of depositional environmental factors, the univariate analysis of TOC content, gray relational analysis (GRA), and robust regression analysis. Two organic matter enrichment patterns were identified: (1) the preservation-dominated pattern under arid climates, governed by intense reducing environments, and (2) the productivity-driven pattern under humid climates, enhanced by terrestrial input. Full article