Search Results (85)

Aquatic fungi serve as core ecological engines in freshwater ecosystems, driving organic matter decomposition and energy flow to sustain environmental balance. Wetlands, with their distinct hydrological dynamics and nutrient-rich matrices, serve as critical habitats for these microorganisms. As an internationally designated Ramsar Site, Yunnan Dashanbao Black-Necked Crane National Nature Reserve in China not only sustains endangered black-necked cranes but also harbors a cryptic reservoir of aquatic fungi within its peat marshes and alpine lakes. This study employed high-throughput sequencing to characterize fungal diversity and community structure across 12 understudied wetland sites in the reserve, while analyzing key environmental parameters (dissolved oxygen, pH, total nitrogen, and total phosphorus). A total of 5829 fungal operational taxonomic units (OTUs) spanning 649 genera and 15 phyla were identified, with Tausonia (4.17%) and Cladosporium (1.89%) as dominant genera. Environmental correlations revealed 19 genera significantly linked to abiotic factors. FUNGuild functional profiling highlighted saprotrophs (organic decomposers) and pathogens as predominant trophic guilds. Saprotrophs exhibited strong associations with pH, total nitrogen, and phosphorus, whereas pathogens correlated primarily with pH. These findings unveil the hidden diversity and ecological roles of aquatic fungi in alpine wetlands, emphasizing their sensitivity to environmental gradients. By establishing baseline data on fungal community dynamics, this work advances the understanding of wetland microbial ecology and informs conservation strategies for Ramsar sites. Full article

The use of cellular energy allocation (CEA) as a physiological energetic biomarker is useful for detecting the sublethal effects of environmental contaminants. The CEA assesses the health and energy status of organisms, serving as a reliable indicator for monitoring the health of aquatic ecosystems. This study aimed to evaluate the impact of emerging contaminants already listed as a priority for monitoring in freshwater ecosystems, namely sulfamethoxazole (0.156–2.50 mg/L), trimethoprim (25.0–400 mg/L), 4-chloroaniline (5.21–20.0 mg/L), and 3,4-dichloroaniline (0.38–4.00 mg/L), on the CEA of D. rerio embryos. A standard fish embryo toxicity test was conducted, and an adaptation of the allometric scaling approach was developed through the relationship between the size and the fresh weight of the embryos. All the compounds affected the fractions of the energy reserves (total carbohydrate, lipid, and protein contents) differently, with carbohydrates being the predominant energy fraction and the most responsive indicator. Although the energy consumed showed no significant changes, the CEA was notably altered after exposure to all the contaminants, indicating a direct connection to shifts in the available energy. The CEA alterations may indicate a reallocation of energy toward detoxification, combating the stress of contaminant exposure. Energy allocation biomarkers provide a comprehensive assessment of an organism’s physiological state, which is essential for evaluating emerging contaminants’ impacts, safeguarding aquatic ecosystems, and shaping effective environmental policies. Full article

Olyokma Nature Reserve, where we conducted our research, is in Eastern Siberia in the middle taiga zone in an area characterized by continuous permafrost. This is the only protected area in the region with a complete reserve regime, where there is no human activity. Here, we studied 14 different types of water bodies located along the Olyokma River valley, 13 of which were studied for the first time. For some of the studied water bodies, a high content of biogenic elements was noted, which may be associated with the characteristics of permafrost water bodies, which are under nutrient release from permafrost thaw. The concentration of several biogenic elements, including ammonium, nitrates and phosphates, increases in the water of the lakes toward the bottom of the river valley. In the composition of various communities of these water bodies, including both planktonic and non-planktonic, we identified 246 species and varieties of microalgae. The abundance and biomass of phytoplankton, as well as the number of species, decreased down the river valley. At the same time, at the upper stations there were more diatoms; while at the stations down the valley, green algae came to the fore; and even lower down, cyanobacteria prevailed. At the lower stations, the indicators of microalgae development were minimal. In accordance with the bioindicative properties of microalgae, a decrease in the trophic status of water bodies was noted down the river valley, which, in our opinion, is a characteristic feature of the waters of an undisturbed catchment basin in the permafrost area. This indicates that the studied aquatic ecosystem changes within a set of environmental and biological indicators, that is, it exists in natural conditions for this catchment basin. Research on the territory of Olyokma Nature Reserve allowed us to obtain information on natural transformation and removal of nutrients in permafrost catchments, while excluding the likelihood of anthropogenic impact on these processes. Full article

Harmful Raphidiopsis raciborskii blooms threaten aquatic ecosystems via toxin production, hypoxia induction, and biodiversity loss. To elucidate the synergistic regulatory mechanisms of Fe³⁺ and phosphorus (P) in cyanobacterial growth, we used a sterile pure culture system under laboratory conditions. We set different phosphorus sources (organic phosphorus and inorganic phosphorus) and low phosphorus concentration of R. raciborskii culture medium for culture, and set different Fe³⁺ addition amount to determine the basic growth index of cyanobacteria cells and the phosphorus content of different components. The results revealed that under conditions of sufficient inorganic phosphorus, there was a logarithmic relationship between ferric ammonium citrate (Fe³⁺) and the specific growth rate of R. raciborskii. Fe³⁺ > 2 mg/L enhanced IPS enrichment and biomass accumulation. However, in oligotrophic or mesotrophic environments with low inorganic phosphorus concentrations, the effect of Fe³⁺ on the growth of R. raciborskii contrasted with that observed in high-IP (eutrophic) environments, exhibiting a pattern of ‘low promotion and high inhibition’. Under organic phosphorus conditions, R. raciborskii converted phosphorus by increasing alkaline phosphatase activity (APA), but this metabolic compensation failed to restore physiological functions, resulting in growth suppression and enhanced cellular phosphorus reserves. Our results establish quantitative linkages between Fe³⁺-P co-limitation thresholds and algal adaptive responses, providing mechanistic insights for controlling bloom dynamics through targeted manipulation of Fe-P bioavailability. Full article

Mountain ecosystems offer valuable opportunities to study species distribution and diversity along altitudinal gradients, particularly for amphibians. This research examined amphibian species distribution, diversity, and conservation across an elevational gradient in the Tangjiahe National Nature Reserve, part of the Hengduan Mountains in southwestern China. A total of 25 amphibian species, encompassing 8 families and 2 orders, were documented, including three newly recorded species: Fejervarya kawamurai, Polypedates braueri, and Boulenophrys minor. Among these, eight species were designated as “threatened” under IUCN criteria and are listed on China’s Biodiversity Red List. Caijiaba exhibited the highest species diversity, whereas Shuichiping had the lowest. Fourteen species were found in terrestrial-farmland and aquatic-lotic habitats, which supported the greatest species richness. The distribution pattern along the altitudinal gradient showed peaks in species richness at 900–1100 m and 1900–2100 m elevation bands, with higher elevations displaying reduced richness. These findings highlighted the spatial characteristics of amphibian distribution and diversity across altitudinal ranges in the Tangjiahe National Nature Reserve and provide insights for formulating conservation policies and adaptive habitat management strategies. Full article

This study investigated the impact of land use change on water quality in the Xinxian River Basin amidst rapid urbanization. While previous studies have predominantly focused on single-scale buffer analyses or specific land use types, the interactions between multi-scale riparian buffers and diverse land cover dynamics remain rarely understudied, particularly in a rapidly urbanizing county in the Yangtze River Basin. Land use type data for the Xinxian River Basin in 2000, 2010, and 2020 were acquired using GIS technology, and subsequent analysis quantified land use pattern changes over this 20-year period. Additionally, 2023 land use data for riparian buffer zones (50 m, 100 m, 200 m, 400 m, and 600 m) were obtained via GIS and subjected to Redundancy Analysis (RDA) with 2023 water quality monitoring data to evaluate the impact of land use on water quality. The results revealed significant land use conversion dynamics, particularly between natural and anthropogenic cover types. Forest cover exhibited negative correlations with riverine nutrient concentrations, while built-up areas displayed strong positive associations, especially at finer scales (50–100 m buffers). Notably, the dominant influencing factor shifted from built-up land at smaller buffer scales (50–100 m) to forest land at larger scales (400–600 m), whereas agricultural land showed no significant correlation. These findings highlight scale-dependent relationships between land use and aquatic ecosystems, emphasizing the critical role of spatial planning in mitigating urbanization impacts. The work is conducive to the sustainable development of Longgan Lake National Wetland Nature Reserve and the protection of water ecology in the middle and lower reaches of the Yangtze River. Full article

The assessment of surface water quality of the Danube River and Black Sea was performed taking into account the amounts determined for heavy metals (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn), nutrients (compounds of N and P, chlorophyll a), emerging contaminants (CECs) (pharmaceutics and endocrine disruptors—19 quantified compounds, out of 30 targeted chemicals), heterotrophic bacteria and total coliforms, in thirty-two locations from the lower Danube sector (starting with km 375 up to the river mouths), the Danube Delta Biosphere Reserve (three Danube branches—Chilia, Sulina, and Sf. Gheorghe) and the Romanian coastal area of the Black Sea. The heavy metals levels were found in the following ranges: 3.0–6.5 μg/L As; 0.51–1.32 μg/L Cd; 21.6–61.2 μg/L Cr; 10.2–28.6 μg/L Cu; 196–351 μg/L Mn; 12.3–47.67 μg/L Ni; 5.2–15.5 μg/L Pb; 44–74 μg/L Zn; 0.01–0.08 μg/L Hg. The nutrient concentrations vary in the intervals: 0.04–0.45 mg/L N-NH₄; 0.01–0.06 mg/L N-NO₂; 0.07–1.9 mg/L N-NO₃; 1.0–3.2 mg/L N total; 0.01–0.05 mg/L P-PO₄; 0.02–0.27 mg/L P total, and 0.8–17.3 μg/L chlorophyll a. The concentrations of CECs from various classes (sulfamethoxazole, trimethoprim, ciprofloxacin, flumequine, amoxicillin, cefuroxime, dicloxacillin, carbamazepine, pravastatin, erythromycin, piroxicam, ketoprofen, diclofenac, naproxen, enilconazole (imazalil), clotrimazole, drospirenone, 17α-ethinylestradiol, and bisphenol A) were compared with values reported for European rivers and the Danube River water in various river sectors. The highest detection frequencies were registered for bisphenol A (100%), sulfamethoxazole (96%), carbamazepine and diclofenac (87%), trimethoprim (78%), pravastatin (46%), and imazalil (34%). Bisphenol A exhibited the largest concentrations (342 ng/L), followed by diclofenac (132 ng/L), carbamazepine (38 ng/L), and sulfamethoxazole (36 ng/L). For most of the contaminants, Black Sea coastal water showed lower concentrations than the Danube water and good ecological status for surface water. Correlations between CECs and total coliforms suggest insufficient treated wastewater effluents as a common contamination source and possible use of CECs as indirect fecal pollution indicator in aquatic systems. This is the first study carried out in the connected system Danube River–Danube Delta–Black Sea for a large palette of toxicants classes and microbial pollutants, which will serve as a baseline for future monitoring of water quality in the region. Full article

The wild resources of Spinibarbus caldwelli, once an important economic fish in southern China, have been drastically reduced in recent years due to environmental changes and human activities. The Liuxi River S. caldwelli National Aquatic Germplasm Reserve was established in Conghua District, Guangzhou city, and the release of S. caldwelli was carried out. However, traditional fishery resource survey methods yield less accurate results when the abundance of the surveyed species is low or when they are difficult to catch. As a non-destructive and non-invasive approach, environmental DNA (eDNA) is widely employed in aquatic species monitoring, though its detection efficiency may be affected by environmental conditions. Therefore, this study explored the eDNA monitoring methods of S. caldwelli in Liuxi River from the following four aspects: (1) the relationship between eDNA release and biomass/abundance; (2) the concentration and diffusion range of eDNA over time in a lentic ecosystem; (3) the diffusion range of eDNA in a lotic ecosystem; and (4) the effects of eDNA application in field monitoring. Our results showed a correlation between eDNA concentration and abundance/biomass of S. caldwelli. eDNA of S. caldwelli can diffuse up to 18 m in lentic ecosystems within 2 h and decreases with distance. eDNA of S. caldwelli released by 10 individuals in Liuxi River could be detected 900 m downstream. Field studies in Liuxi River showed that the eDNA method has high sensitivity in detecting the presence or absence of species and is highly consistent with the results of traditional methods. This study explored the application of environmental DNA technology in species monitoring in Liuxi River. Our aim was to evaluate the applicability and potential of eDNA in ecological monitoring of stream fishes. Full article

Extreme drought events, intensified by climate change, critically threaten aquatic ecosystem stability by restructuring phytoplankton communities. However, the mechanisms underlying drought-driven community assembly remain poorly understood. This study investigated the impacts of extreme drought on phytoplankton community dynamics in the aquatic reserves of Jiujiang City, China, a critical ecotone of the Yangtze River and Poyang Lake. Through multi-temporal sampling (2022–2023) across 12 sites, we integrated taxonomic, functional group, and co-occurrence network analyses with environmental driver assessments. The results revealed that extreme drought significantly reduced phytoplankton species diversity and triggered a functional shift from disturbance-adapted (e.g., MP group) to pollution-tolerant taxa (e.g., W1 group). Deterministic processes dominated community assembly, driven by drought-induced environmental filtering through water temperature, dissolved oxygen, and nutrient fluctuations. Copper emerged as a key stressor, correlating with the abundance of Cryptophyta. Co-occurrence networks, cohesion, and robustness exhibited heightened complexity and stability under extreme drought, emphasizing stress-induced mutualistic interactions. Our findings elucidate how drought reshapes phytoplankton communities via nutrient dynamics and deterministic species interactions, offering critical insights for managing aquatic ecosystems under escalating climatic extremes. Full article

Wetlands are transitional lands between terrestrial and aquatic systems that provide various ecosystem services. The objective of this study was to evaluate the change in wetlands in the Chimborazo Wildlife Reserve (CR) in the period 1986–2022 using geographic information systems (GISs), multitemporal satellite data, and field data from the 16 wetlands of the reserve. Images from Landsat satellite collections (five from Thematic Mapper, seven from Enhanced Thematic Mapper, and eight from Operational Land Imager and Thermal Infrared Sensor) were used. Image analysis and processing was performed, and the resulting maps were evaluated in a GIS environment to determine the land cover change and growth rate of hydrophilic opportunistic vegetation (HOV) according to hillside orientation. The results show that there are negative annual anomalies in the water-covered areas, which coincide with the increase in HOV. This shows that the constancy or increase in the rate of increase in HOV, which varies between 0.0018 and 0.0028, causes the disappearance of these ecosystems. The importance of the study lies in its potential contribution to the decision-making process in the management of the CR. Full article

Direct access to good-quality drinking water in Uzbekistan is becoming a major issue. This challenge is exacerbated by growing demands, driven by population growth, industrial development, and desert land cultivation. In this regard, there is a significant need for a thorough analysis of the existing water resources. This study aims to identify the chemical composition of springs’ water in the Kashkadarya region of Uzbekistan and to assess their suitability as drinking water sources. To analyze the water quality, three springs were selected, Hazrat Bashir, Boshmanbulak, and Chillabulak, which are the most used springs by the population of this region, and the artesian waters of the city of Shakhrisabz were also included in the study. The quality of the spring water was evaluated based on the primary water quality indicators, including salt composition, heavy metals, and some essential trace elements such as iron (Fe), chromium (Cr), and selenium (Se) in the selected samples. According to the results, the spring water in Chillabulak was found to be relatively harder than the other samples, with magnesium and calcium concentrations of 28 and 390 mg/L, respectively. However, the study also revealed that the water from the other three examined samples meets sanitary norms and water quality standards, confirming their suitability for human consumption. The results can be used to develop water quality management strategies and environmental protection, as well as to inform the population about the ecological safety of regional aquatic reserves. Full article

The Integrated Valuation of Ecosystem Services and Trade-Offs (InVEST) model with the distributed hydrological model Soil and Water Assessment Tool (SWAT) were implemented. The SWAT model quantifies and visualizes water production and groundwater reserves in the Mudanjiang River Basin, employing the groundwater runoff modulus method to calculate groundwater recharge in the basin. This study aims to assess the model’s applicability in cold basins and subsequently analyze groundwater distribution characteristics, water reserves, and the exploitable volume. It serves as a reference for the judicious allocation of groundwater resources and the preservation of the local aquatic ecosystem. The study indicates the following: (1) Utilizing the monthly runoff data from the Mudan River hydrologic station, SWAT simulation and calibration were conducted, yielding a determination coefficient (R²) of 0.75 and a Nash–Sutcliffe efficiency coefficient (NS) of 0.77, thereby satisfying fundamental scientific research criteria. The water yield predicted by the InVEST model aligns closely with the water resources bulletin of the research region. (2) The data from the water production module of the InVEST model indicate that the average annual water production during the research period was 6.725 billion m³, with an average annual water production depth of 148 mm. In 2018, characterized by ample water supply, the water output was at its peak, with a depth of 242 mm. In 2014, the water depth recorded was merely 16 mm. (3) Throughout the study period, the average annual flow of the Mudan River was 4.2 billion m³, whereas the groundwater reserve was 24.13 (10⁸ m³·a⁻¹). In 2013, the maximum groundwater reserve was 38.42 (10⁸ m³·a⁻¹), while the minimum reserve in 2014 was 2.36 (10⁸ m³·a⁻¹), suggesting that the region was predominantly experiencing sustainable exploitation. (4) The mean groundwater runoff modulus is 0.28 L/(s·km²), with a peak annual recharge of 15.4 (10⁸ m³·a⁻¹) in 2013 and a lowest recharge of just 3.2 (10⁸ m³·a⁻¹) in 2011. Full article

The Belostomatidae is a family of aquatic Heteropteran insects that normally inhabit swamps of tropical, subtropical and temperate regions where they naturally feed on a large range of prey, mainly fish, amphibians and reptiles. However, these arthropods can occasionally bite humans when provoked, causing pain. The only species of giant water bug known to be found in Europe is Lethocerus (L.) patruelis. We reported the finding of a specimen of female L. patruelis in Southern Italy. The arthropod was collected by a tourist on his body while he lying down on a beach close to a nature reserve. To finalize the giant water bug identification, both morphological and molecular tools were used for the first time in our country. Herein, information on cases of patients bitten by giant water bugs belonging to the Belostomatidae family are reported, and circumstances involving their contact with humans are also discussed. Full article

By 2030, the global deficit in freshwater resources is projected to reach 40%, in direct correlation with global population growth. To cope with this increase in demand, the Sustainable Development Goals outlined by the United Nations, specifically goal No. 6 of the 2030 agenda, have identified wastewater as a new resource. Indeed, the reuse of wastewater offers three primary advantages: (i) Reused wastewater can serve as an alternative to water from natural reserves, particularly in sensitive geographical areas experiencing water stress. (ii) Wastewater reuse limits the discharge of treated water into the natural environment, which is often a source of pollution, thus helping preserve ecosystems. (iii) Wastewater reuse also facilitates the extraction of valuable compounds, such as fertilisers and precious metals, along with energy generation. This review focuses on various uses of water and the global reuse of treated wastewater from wastewater treatment plants (WWTPs). The focus then shifts to pesticides, exploring the origins of these emerging contaminants and their impacts on aquatic environments. An in-depth analysis of diuron follows, examining its origin, toxicity and regulation and the performance of existing advanced treatments to produce safe water from WWTP effluents. Full article

Coastal wetlands deliver essential ecosystem services, including cultural services, which provide non-material benefits such as recreation, education, and spiritual enrichment that are crucial for human well-being. This study investigates the cultural ecosystem services provided by a 40 ha coastal wetland in the Gulf of Manfredonia, southern Italy, within the Gargano National Park. By integrating an ecological survey of the bird community with a social survey of visitors to the King’s Lagoon Nature Reserve, the content of tailored planning strategies and management tools for the conservation of wetland biodiversity was developed. An ecological analysis of the bird community was carried out on the assumption that it could be representative of the total biodiversity observed in the wetland. On the other hand, a questionnaire was used to collect information from visitors to the reserve, highlighting the aspects of the wetland that they found most interesting and attractive according to their judgement and beliefs, and thus targeting a specific set of cultural ecological services. The two approaches were then combined to develop a comprehensive strategy. The bird community analysis led to the identification of the mixed biotope category (a combination of wetlands, aquatic/riparian ecosystems, semi-natural vegetated areas, and meadows together with agricultural areas) as the reference biotope for prioritizing wetland management. The Ardeidae family was chosen as a bird flagship group because of its high visibility, ease of identification, attractiveness to visitors, wide local distribution, and fairly constant presence in the study area throughout the year. Flagship species have a dual function: to guide conservation measures and actions by wetland managers, and to attract the interest, curiosity and active participation of potential visitors to the wetland. Based on the results, a list of guidelines for improving the birds’ habitats and providing them with resources (feeding, breeding, shelter, roosting, etc.) has been proposed. The aim of these measures is to optimize the presence and abundance of Ardeidae as flagship species, thereby preserving the biodiversity heritage in general and increasing the provision of cultural ecosystem services in the wetland. The resulting dynamic interplay ensures that both natural and cultural resources are fully and appropriately valued, protected, and maintained for the benefit of present and future generations. Full article