International Review of Hydrobiology最新文献

Lentic ecosystems are vulnerable to contamination by trace elements, which can accumulate and pose risks to aquatic life and human health. In a large, developing country such as Brazil, marked by vast geographic, environmental, and socioeconomic diversity, it is crucial to understand how these factors shape research on this group of contaminants. Here, we conducted a systematic review of 65 studies published between 1980 and 2023 on Brazilian urban lentic systems, retrieved from Web of Science and Scopus databases. Research output increased sharply after 2011, with 73% of studies published in the last decade. Geographically, half of the studies were conducted in the Southeast region, especially in large urban areas within the Atlantic Forest biome, while the North and Central-West regions together accounted for less than 15%. Industrial zones were the most frequently studied land use, and sediment was the most common matrix. Copper, lead, chromium, zinc, and nickel were the most frequently reported trace elements, whereas toxic elements such as arsenic and mercury were infrequently studied. This review provides a quantitative synthesis of research on trace element contamination in Brazilian urban lentic ecosystems. The findings highlight critical gaps, including the underrepresentation of North and Central-West regions, the limited use of biological matrices, and the neglect of mercury and arsenic, despite their ecological and toxicological relevance. Addressing these gaps is essential to improve ecotoxicological risk assessments, strengthen the integration between environmental monitoring and public health, and guide evidence-based policies for pollution control in vulnerable aquatic systems.

Fatty acids (FAs) are biochemical molecules with vital structural and metabolic functions in all living organisms. Over the last decades, FA analysis in ecological studies has garnered significant attention due to its diverse applicability, such as taxonomic support for species identification, investigations on trophic interactions, and environmental monitoring of aquatic ecosystems. Here, we reviewed the usage of FAs in ecological studies analyzing environmental changes in freshwater systems by applying a Topic Modelling Analysis to a total of 119 papers previously extracted by a systematic search in Web of Science, followed by ordination analyses. The analysis revealed topic similarities among publications and assessed topic popularity—hot, neutral, and cold topics—based on their prevalence over the years. Topics such as “Seasonality and land-use effects”, “Environmental/temperature stress in biofilms”, “Highly Unsaturated Fatty Acids (HUFAs) in plankton”, and “FAs in fish tissues” were classified as hot topics, with the first two experiencing an increasing trend since 2015. Topics classified as neutral included “Total lipids in invertebrates” and “FAs in river organic matter”. Cold topics included “Food quality for Daphnia”, “FA markers in sediments”, and “Trophic transfer in reservoirs/fish farms”. Topic modeling revealed 12 distinct research topics, indicating that the use of FAs as markers for environmental changes in freshwater ecosystems is a diverse and multifaceted field. This research spans various communities, ecosystem compartments, and types of environmental change, with most topics showing a stable publication trend over time. To enhance future research in this area, it is recommended that FA fingerprinting be further developed to target specific impacts and communities, particularly in the context of multiple stressors on freshwater ecosystems.

Barrier removal is a common stream restoration practice aimed at restoring longitudinal connectivity, yet its effects on biofilm structure and function, through alteration of near-bed hydrodynamics, remain unclear. Using a space-for-time substitution approach, we assessed how the presence and removal of a low-head dam affect biofilm structure and function. We quantified near-bed hydrodynamics and biofilm structure and function across three reaches in a temperate stream: one impacted by a low-head dam, one in reference condition, and one restored where a low-head dam was removed over a decade ago. In each reach, we quantified near-bed hydrodynamics, and biofilm structural (microbial α-diversity, biomass, Chlorophyll a, bacterial abundance) and functional parameters (nitrate (N-NO₃⁻) and dissolved organic carbon (DOC) uptake), along with microbial community composition. We found that the low-head dam altered near-bed hydrodynamics, as well as biofilm structure and function. Restoration successfully reestablished near-bed hydrodynamics similar to those observed at the reference site, which coincided with the recovery of impaired biofilm structural parameters. However, biofilm DOC uptake remained significantly lower in the restored reach compared to the control, indicating a persistent impairment despite restoration. Presence–absence patterns of specific taxa explained a small (15%), but consistent, fraction of the variance in DOC uptake, suggesting that the occurrence of particular microbial groups may be linked to the incomplete DOC uptake recovery. Our results suggest that dam-induced alterations in near-bed hydrodynamics largely explain the structural changes observed in biofilms. Restoring near-bed hydrodynamics supports the recovery of biofilm structure, but functional recovery remains incomplete. Therefore, hydromorphological restoration alone, while necessary, is unlikely to fully restore ecosystem functioning. Our study highlights the need to integrate biological and biogeochemical targets when assessing restoration success.

Barrier removal is a common stream restoration practice aimed at restoring longitudinal connectivity, yet its effects on biofilm structure and function, through alteration of near-bed hydrodynamics, remain unclear. Using a space-for-time substitution approach, we assessed how the presence and removal of a low-head dam affect biofilm structure and function. We quantified near-bed hydrodynamics and biofilm structure and function across three reaches in a temperate stream: one impacted by a low-head dam, one in reference condition, and one restored where a low-head dam was removed over a decade ago. In each reach, we quantified near-bed hydrodynamics, and biofilm structural (microbial α-diversity, biomass, Chlorophyll a, bacterial abundance) and functional parameters (nitrate (N-NO₃⁻) and dissolved organic carbon (DOC) uptake), along with microbial community composition. We found that the low-head dam altered near-bed hydrodynamics, as well as biofilm structure and function. Restoration successfully reestablished near-bed hydrodynamics similar to those observed at the reference site, which coincided with the recovery of impaired biofilm structural parameters. However, biofilm DOC uptake remained significantly lower in the restored reach compared to the control, indicating a persistent impairment despite restoration. Presence–absence patterns of specific taxa explained a small (15%), but consistent, fraction of the variance in DOC uptake, suggesting that the occurrence of particular microbial groups may be linked to the incomplete DOC uptake recovery. Our results suggest that dam-induced alterations in near-bed hydrodynamics largely explain the structural changes observed in biofilms. Restoring near-bed hydrodynamics supports the recovery of biofilm structure, but functional recovery remains incomplete. Therefore, hydromorphological restoration alone, while necessary, is unlikely to fully restore ecosystem functioning. Our study highlights the need to integrate biological and biogeochemical targets when assessing restoration success.

Understanding the trophic ecology and nutrient dynamics of freshwater invertebrates is crucial for evaluating the function and resilience of ecosystems. Although bulk stable isotope analysis is widely used to investigate food web structures, it lacks the resolution required to differentiate between carbon and nitrogen sources at a molecular level. Compound-specific isotope analysis (CSIA) of amino acids (AAs) offers a more detailed approach; however, its application in freshwater ecosystems, particularly across spatial and temporal gradients, remains limited. This study addresses this issue by applying AA-specific δ¹⁵N and δ¹³C analysis to the key detritivore Gammarus spp. across the North Rhine-Westphalia catchment in Germany over 4 years (2016, 2018, 2020, and 2022). Significant spatial variation in δ¹³C values was observed, while temporal trends were less pronounced. Nonessential AAs exhibited higher δ¹³C values than essential AAs, with glycine being the most enriched in ¹³C and lysine and phenylalanine the most depleted. Principal component analysis (PCA) of δ¹³C values revealed variability in carbon sourcing, reflecting shifts between primary producers, microbial inputs, and detrital material. Regarding δ¹⁵N, trophic AAs such as leucine and glutamic acid were enriched, whereas source AAs such as phenylalanine were depleted, confirming their roles in nitrogen metabolism. PCA of δ¹⁵N values revealed that some sites maintained stable nitrogen inputs from autotrophic sources, while others showed increasing contributions from microbial or detrital nitrogen over time. Trophic position (TP) estimates for Gammarus spp. were consistent across sites and years, ranging from 1.1 to 1.5 using the TP_Glu-Phe method and from 1.4 to 1.8 using the TP_5AA method. This confirms their role as primary consumers. These findings emphasize the ecological importance of Gammarus spp. in nutrient cycling and demonstrate the effectiveness of CSIA-AA in unraveling complex trophic interactions and food web dynamics.

Preservation of urban aquatic ecosystems is of primary importance for human well-being, biodiversity protection and the future of society. Lake–groundwater–river interactions within urban floodplains harbour intrinsic fragility, yet remain largely understudied. Appropriate environmental management can help assure the conservation of these sites through strategies that are based on physical, chemical and isotope constraints. Here we present the example of the Groundwater and Lakes Urban Observatory (GLUO) in Magdeburg, Germany, where monitoring has been carried out since 2022. Our database for the year 2023 includes data from the Elbe River, two lakes named Lake Salbker South and Lake Salbker North, and two groundwater wells. Major ion patterns point to the Elbe River and Lake Salbker South as the end-members for water compositions within the system, although contributions from the former appear less significant. Stiff plots suggest the existence of a more saline end-member that may receive inputs from the Zechstein Formation and drives the geochemistry of Lake Salbker South. Dissolved oxygen (DO) concentrations in Lake Salbker South during stratification show a marked depletion in the hypolimnion with values down to 1.8 mg L⁻¹ that we attribute to mineralization of organic matter as well as oxidation of sulphur compounds. This feature acknowledges Lake Salbker South as a natural hydrogen sulphide (H₂S) reactor. Water stable isotope compositions (δ²H_H2O and δ¹⁸O_H2O) of the water bodies within the GLUO outline a trend that is compatible with moderate evaporation. We discuss that dissolution of saline deposits may also play a role. These findings emphasize the need to implement the study of lake–groundwater–river interactions within floodplains, especially when hypertrophic or sulphur-rich water bodies are involved. Due to the inherent vulnerability and potential hazards associated to these environments, we stress the importance of establishing a multidisciplinary monitoring framework to evaluate their geochemical fluxes and ecological integrity.