Ecohydrology最新文献

Lotic environments are among the most vulnerable aquatic ecosystems, and changes occurring in them happen faster than our capacity to measure the impacts, with the choice of community attributes that best reflect these disturbances still unclear. In this study, we evaluated the response of phytoplankton species and species traits along a gradient of urbanization in lowland streams. To do this, we sampled nine streams in three areas classified as densely populated (DP), low populated (LP), and rural areas (RA) during the four seasons (n = 108), considering relevant limnological variables (including metals, herbicides, and inorganic nutrients) and phytoplankton. Phytoplankton was analysed using taxonomic and morpho-functional traits approaches. We used several multivariate analyses to assess phytoplankton species and trait distribution among stream groups (DP, LP, RA) and identify their environmental drivers. We found that phytoplankton responded to the urbanization gradient at both taxonomic and functional levels. However, this response was mediated by the land use (urban vs. rural) rather than its intensity. The main stressors detected were eutrophic conditions and organic matter contamination, which differed among groups (DP-LP and RA). Both approximations indicated eutrophic, organically enriched conditions, but the situation varied among seasons and stream groups. The response of the taxonomic approach was clearer than the traits-based approach, showing differences in density only between stream groups in the summer and the spring. Phytoplankton was responding to the gradient of urbanization in these subtropical lowland streams, but the seasonality, especially temperature and changes in the water column mixing also mediate the effect.

Canopy rainfall interception is one key hydrological process, affecting rainwater redistribution and effectiveness in semiarid regions. Canopy rainfall interception loss is jointly influenced by meteorology, vegetation and topography. The canopy water storage capacity (S), rainfall interception depth (I_m) and ratio (I_%) and vegetation characteristics, together with topographic factors of three grassland communities (dominated by Bothriochloa ischaemum, Lespedeza davurica and Artemisia gmelinii, respectively) were investigated on the Loess Plateau of China during the main growing season (June to September). Results showed that I_m ranged from 0.55 to 0.89 mm and I_% ranged from 6.14% to 12.1%, with the maximum values occurring in August for three communities, and A. gmelinii community had the largest I_m (0.89 mm) and I_% (12.1%). The I_m and I_% were positively correlated with aboveground biomass (AGB), coverage (Cov), leaf area index (LAI), community-weighted mean height (CWMH) and altitude (Alt), but negatively correlated with slope degree and rainfall intensity (RI). Hierarchical partitioning analysis (HPA) showed that AGB had the highest contribution for I_m (20.3%), while Alt had the highest contribution for I_% (18.2%). The regression models based on forward selection could effectively predict the values of I_m (R² = 0.802, RMSE = 0.049) and I_% (R² = 0.546, RMSE = 1.434). Topographic factors (altitude, slope degree and aspect) indirectly influenced both I_m and I_% by modulating vegetation characteristics (AGB, Cov, etc.). All these indicated that aboveground biomass mainly determines grassland community rainfall interception loss in the semiarid Loess Plateau.

As one of the responses to the global commitments against climate change, the Ethiopian Government launched a nationwide Green Legacy Initiative (GLI) in 2019, which largely focused on forest tree plantations with some inclusion of fruit trees. Despite its tremendous efforts and investments, its effectiveness and impacts have not been studied. This paper attempted to address this necessity by conducting a cross-sectional quasi-experiment in three randomly selected woredas/districts of Lake Hawassa Watershed from August 20 to September 2, 2023. The research hypothesized the likely impacts of GLI on four dependent variables (hydrological regulation, soil stability, nutrient cycling and plant species diversity). To achieve this, the research considered the two variants of GLI practices (plantation with and without soil and water conservation measures) and the corresponding control sites. Having three sites and three treatments with five replications, the study involved a total of forty-five quadrats of the same size (20 m × 20 m). The first three parameters were analysed using the landscape functionality analysis method, while the fourth employed Shannon's diversity index. Results of ANOVA showed that, on average 87% of randomly selected quadrats were found to significantly improve the local hydrology (runoff potential) (≈ 83.3% with Av. p = 0.012), soil stability (≈100% with Av. p = 0.002), nutrient cycling (≈83.3% with Av. p = 0.017) and plant species diversity (≈83.3% with Av. p = 0.012). The research revealed positive results from the Ethiopian Green Legacy Initiative. The small number of samples is acknowledged as a limitation of the research.

Channel constructions significantly impact river hydrodynamics, subsequently influencing river ecosystems. To mitigate the negative influence of channel construction and protect fish habitat, it is essential to evaluate fish habitat suitability through the integration of hydrodynamic and habitat models. This study models channel constructions on both the left and right riverbanks to evaluate habitat suitability for Four Major Chinese Carps and the Chinese sturgeon. Initially, flow velocity, water depth and grain size are simulated, followed by an assessment of habitat conditions using the Habitat Suitability Index (HSI) for three distinct construction strategies. Results reveal that constructing channels on the left bank mitigates adverse effects on fish habitat, while constructions on the right bank and both riverbanks lead to habitat degradation. Long-term effects on riverbed elevation and fish habitat suitability post-construction were also investigated. Notably, the Four Major Chinese Carps consistently demonstrate greater suitability for the studied river, regardless of flow rate or construction strategies, in comparison to the Chinese sturgeon. These findings underscore diverse responses to channel construction, providing valuable insights for identifying critical habitat areas for endemic fish conservation. This research presents a robust framework for assessing fish ecology in river systems, offering support for conservation decision-makers.

Rainfall partitioning by the vegetation canopy into stemflow (SF) and throughfall (TF) plays a crucial role in soil infiltration and the local water balance. This study aims to quantify the differences in SF and TF between two sand-binding shrubs, Caragana liouana and Salix psammophila, in the desert steppe, clarify the effects of biotic and abiotic factors on them using the boosted regression trees (BRT) model, and compare soil moisture replenishment during the growing seasons of 2021 and 2022. Under identical rainfall conditions, the canopies of C. liouana and S. psammophila can lead to differences in rainfall partitioning. The SF percentage ranged from 0 to 23.70% for C. liouana and from 0% to 3.3% for S. psammophila, respectively, while the TF percentage ranged from 42.12% to 90.07% for C. liouana and from 52.39% to 94.87% for S. psammophila. The funnelling ratio for C. liouana (69.59) is 1.19 times higher than for S. psammophila (58.36). Rainfall amount is the primary variable affecting rainfall partitioning. The average soil moisture replenishment and soil moisture conversion efficiency under the C. liouana canopy are 11.02 mm and 58.39%, respectively, which are significantly higher than those for S. psammophila (4.84 mm and 24.33%, respectively). These findings suggest that C. liouana, with its relatively higher SF and soil moisture conversion capability compared to S. psammophila, plays a significant ecohydrological role in water-limited ecosystems. This study provides a reference for species selection and ecological management in vegetation restoration efforts in desert steppes and similar regions.

The impact of two high-head dams on macroinvertebrate communities within the regulated reaches of the Wujiang River in China was explored, using longitudinal monitoring data spanning from 2006 to 2016. In this study, we set up 10 sampling sites categorized into four areas based on different stressors and defined three stages based on the timeline of dam construction. Our findings revealed significant changes in community composition before and after dam impoundment. While certain original dominant taxa, such as Rivularia globosa and Lithoglyphopsis ovatus, remained dominant throughout the stages, mayflies and caddisflies nearly vanished in the downstream reaches of the dams. This trend was accompanied by the disappearance of taxa with low adaptability and the emergence of tolerant taxa downstream of the dams. Additionally, typical limnological taxa colonized the inundated reaches. Dam impoundment affected not only macroinvertebrate community composition but also diversity. In this study, the recovery effect of communities downstream of dams was not observed due to the limited distance, but the presence of Wujiangdu Dam upstream of the two dams for over 20 years makes us believe that in a large river system, macroinvertebrate communities downstream of high-head dams may fully recover if the distance from the dams is long enough. The original and vulnerable species R. globosa, which demonstrated remarkable adaptability and thrived downstream of dams, should be further studied in the future.

In freshwater systems, carbon, nitrogen, and phosphorus are essential macroelements. Changing ecological communities as a result of anthropogenic activity and climate change has become a global issue. C:P has been demonstrated to be a trustworthy and sensitive assay for detecting and monitoring single or multiple species in a wide range of samples. We look at how C:P can be utilized to manage and reduce eutrophication and harmful algal blooms (HABs) in freshwater environments in this review work. Recent research show how C:P has been shown to be a useful strategy for gathering complete data in freshwater ecosystem studies. The total number of papers in ScienceDirect from 2000 to 2023 with the terms “carbon and phosphorus ratios, fresh water ecosystems, and phytoplankton” in the title, abstract, or keywords was acquired for this review. Based on the number of published research demonstrating an increased understanding of the basic scientific concepts behind the carbon and phosphorus ratio, the overall temporal trend in publications on the ratio showed a steady growth. Compared to eutrophic Lake Victoria, which had a C:P of 149, mesotrophic Lakes Malawi and Kivu had a ratio of 263. Applying the carbon-to-phosphorus ratio to lake and reservoir eutrophication assessment is feasible, and the increasing C:P ratio serves as a prime indicator for the initiation of lake and reservoir reoligotrophication. Our findings establish the framework for future study into the relationship between organic nutrients and eutrophication, as well as the ecological ramifications of these relationships in freshwater systems. Furthermore, our prediction was that increases in C:P would change the structure of phytoplankton communities.

Ecological models hold significant potential for advancing lake research. In this study, we employed CiteSpace, a bibliometric analysis tool, and VOSviewer, a visualisation software, to facilitate a comprehensive understanding of recent advancements in ecological modelling within the context of lake research. The objective was to furnish valuable references in support of the widespread application of ecological models in aquatic environments. Using the 4688 articles collected in the Web of Science (WoS) core database as the sample data source, conducting corresponding data mining and quantitative analysis through visualisation analysis software such as CiteSpace and VOSviewer. From the perspectives of literature output patterns, keyword co-occurrence networks and future research directions, in-depth quantitative and visual analysis is carried out on the current status of research on lake ecological models, research institutions, journal publication situations, prolific authors and research hot topics. Through meticulous examination of literature and organisational categorisation techniques, we systematically scrutinised and synthesised the present state, limitations and noteworthy considerations associated with models such as EFDC, CE-QUAL-W2, DYRESM-CAEDYM, AQUATOX, Vollenweider, PCLake, MIKE, WASP and Deflt3D in the context of lake research. Our findings reveal that research focal points from 2002 to 2022 encompass climate change, the ramifications of eutrophication on aquatic ecosystems and the effects of phytoplankton and resuspended sediments on lake management.

The ecology of forested floodplains is intricately linked to river hydrology through the frequency, magnitude, timing and duration of floodplain inundation. Spatial variability in inundation characteristics is influenced by the geomorphic template of a floodplain, both in terms of the topography of floodplain features and connectivity of these features to the main river channel. Spatial variability in inundation, in turn, has the potential to produce spatial variability in forest ecological characteristics. This study examines the influence of floodplain geomorphic features on spatial variability in inundation frequency as well as the relationship between these geomorphic features and the ecological characteristics of a floodplain forest. The frequencies of floods of different magnitudes are determined from flow-duration analysis of over 100 years of discharge data for a lowland meandering river in Illinois, USA. Data on discharge, stage, and topography are then used to calibrate a two-dimensional hydraulic model of flow across the floodplain at different levels of inundation. Integrating the frequency and inundation data yields mapping of average annual inundation frequency for different parts of the floodplain. Significant differences in inundation frequency correspond to three distinct floodplain geomorphic features: secondary channels (frequency = 12%), closed depressions (frequency = 4%) and the floodplain surface (frequency = 3%). Tree density is similar among the three types of geomorphic features, but tree species composition and canopy density differ significantly between secondary channels and the floodplain surface. The results provide insight into linkages among hydrology, geomorphology and tree characteristics of forested floodplains of lowland meandering rivers.

The saturation of total dissolved gases (TDG) in water remains around 100%. Certain circumstances can lead to TDG values exceeding 100%, resulting in TDG supersaturation (TDGS). TDGS above about 110% can be toxic to animals that rely on water for gas exchange. However, saturation beyond 200% can occur in freshwater downstream of dams and hydroelectric power plants. Despite its impact, TDGS is often overlooked as a hazard to aquatic life, particularly for benthic macroinvertebrates. This study aimed to examine the effects of TDGS on nine species of benthic macroinvertebrates. We used replicated tank studies to manipulate TDGS levels from 100% to 120% and investigated the overall survival and species-specific effects on survival and buoyancy. We also present a summary on the effects of TDGS on invertebrate species previously tested. The results indicate that seven of nine species exhibited increased buoyancy when exposed to TDGS, causing them to float on the water surface. Additionally, a Cox Proportional Hazards model revealed a significant effect of TDGS on the survival of the macroinvertebrates. The sensitivity towards TDGS varied greatly among species of benthic macroinvertebrates, and significant species-specific effects were only observed for Isoperla grammatica, Baetis rhodani and Asellus aquaticus. Among these, the two latter species showed clear dose-related effects caused by TDGS, enabling the assessment of LT50 (time required to kill half of the tested population). B. rhodani was most sensitive with a LT50 of 3.7 days at 119% TDGS. Both species had visible air bubbles under the exoskeleton. Our findings highlight that direct and indirect effects on benthic macroinvertebrates can occur even at low to moderate levels of gas supersaturation, likely causing reduced density, decreased species diversity and altered species composition. The emerging evidence strongly supports the implementation of regulations on TDGS in freshwaters.