Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
1,467
result(s) for
"Stream ecology Case studies."
Sort by:
The riverscape and the river
The study of water in the landscape is a new and rapidly expanding field. Dr Haslam examines how the quantity, function and ecology of water changes as it moves from watershed to river.
Book
Seasonality and predictability shape temporal species diversity
Temporal environmental fluctuations, such as seasonality, exert strong controls on biodiversity. While the effects of seasonality are well known, the predictability of fluctuations across years may influence seasonality in ways that are less well understood. The ability of a habitat to support unique, non‐nested assemblages of species at different times of the year should depend on both seasonality (occurrence of events at specific periods of the year) and predictability (the reliability of event recurrence) of characteristic ecological conditions. Drawing on tools from wavelet analysis and information theory, we developed a framework for quantifying both seasonality and predictability of habitats, and applied this using global long‐term rainfall data. Our analysis predicted that temporal beta diversity should be maximized in highly predictable and highly seasonal climates, and that low degrees of seasonality, predictability, or both would lower diversity in characteristic ways. Using stream invertebrate communities as a case study, we demonstrated that temporal species diversity, as exhibited by community turnover, was determined by a balance between temporal environmental variability (seasonality) and the reliability of this variability (predictability). Communities in highly seasonal mediterranean environments exhibited strong oscillations in community structure, with turnover from one unique community type to another across seasons, whereas communities in aseasonal New Zealand environments fluctuated randomly. Understanding the influence of seasonal and other temporal scales of environmental oscillations on diversity is not complete without a clear understanding of their predictability, and our framework provides tools for examining these trends at a variety of temporal scales, seasonal and beyond. Given the uncertainty of future climates, seasonality and predictability are critical considerations for both basic science and management of ecosystems (e.g., dam operations, bioassessment) spanning gradients of climatic variability.
Journal Article
Rethinking biodiversity patterns and processes in stream ecosystems
A major goal of community ecology is understanding the processes responsible for generating biodiversity patterns along spatial and environmental gradients. In stream ecosystems, system-specific conceptual frameworks have dominated research describing biodiversity change along longitudinal gradients of river networks. However, support for these conceptual frameworks has been mixed, mainly applicable to specific stream ecosystems and biomes, and these frameworks have placed less emphasis on general mechanisms driving biodiversity patterns. Rethinking biodiversity patterns and processes in stream ecosystems with a focus on the overarching mechanisms common across ecosystems will provide a more holistic understanding of why biodiversity patterns vary along river networks. In this study, we apply the theory of ecological communities (TEC) conceptual framework to stream ecosystems to focus explicitly on the core ecological processes structuring communities: dispersal, speciation, niche selection, and ecological drift. Using a unique case study from high-elevation networks of connected lakes and streams, we sampled stream invertebrate communities in the Sierra Nevada, California, USA to test established stream ecology frameworks and compared them with the TEC framework. Local diversity increased and β-diversity decreased moving downstream from the headwaters, consistent with the river continuum concept and the small but mighty framework of mountain stream biodiversity. Local diversity was also structured by distance below upstream lakes, where diversity increased with distance below upstream lakes, in support of the serial discontinuity concept. Despite some support for the biodiversity patterns predicted from the stream ecology frameworks, no single framework was fully supported, suggesting “context dependence.” By framing our results under the TEC, we found that species diversity was structured by niche selection, where local diversity was highest in environmentally favorable sites. Local diversity was also highest in sites with small community sizes, countering the predicted effects of ecological drift. Moreover, higher β-diversity in the headwaters was influenced by dispersal and niche selection, where environmentally harsh and spatially isolated sites exhibit higher community variation. Taken together our results suggest that combining system-specific ecological frameworks with the TEC provides a powerful approach for inferring the mechanisms driving biodiversity patterns and provides a path toward generalization of biodiversity research across ecosystems.
Journal Article
Evaluating the potential of treated effluent as novel habitats for aquatic invertebrates in arid regions
Increasing anthropogenic demands for freshwater have altered many aquatic systems, including the drying of formerly perennial streams. The discharge of treated effluent has returned perennial flow in some of these streams, especially in arid and semi-arid regions, but the ability of treated effluent to support diverse aquatic communities is poorly understood. We examined the potential of treated effluent to create aquatic invertebrate habitat using the effluent-dependent Santa Cruz River in southern Arizona, USA as a case study. We identified 92 invertebrate taxa across our ten sampling sites and two sampling dates. Community composition was primarily shaped by water quality but also by stream drying (on daily time scales) and benthic substrate. Specifically, Linear Mixed-Effects models revealed a strong positive relationship between dissolved oxygen and taxonomic richness and a strong negative relationship between stream drying and invertebrate density. Although there are unique challenges to biota in effluent-dependent systems, our results suggest that treated wastewater could be managed to augment or recreate aquatic habitats that have been otherwise diminished or lost.
Journal Article
An efficient strategy for predicting river dissolved oxygen concentration: application of deep recurrent neural network model
Dissolved oxygen (DO) concentration in water is one of the key parameters for assessing river water quality. Artificial intelligence (AI) methods have previously proved to be accurate tools for DO concentration prediction. This study presents the implementation of a deep learning approach applied to a recurrent neural network (RNN) algorithm. The proposed deep recurrent neural network (DRNN) model is compared with support vector machine (SVM) and artificial neural network (ANN) models, formerly shown to be robust AI algorithms. The Fanno Creek in Oregon (USA) is selected as a case study and daily values of water temperature, specific conductance, streamflow discharge, pH, and DO concentration are used as input variables to predict DO concentration for three different lead times (“t + 1,” “t + 3,” and “t + 7”). Based on Pearson’s correlation coefficient, several input variable combinations are formed and used for prediction. The model prediction performance is evaluated using various indices such as correlation coefficient, Nash–Sutcliffe efficiency, root mean square error, and mean absolute error. The results identify the DRNN model (
CC
Testing
=
0.97
,
N
S
E
Testing
=
0.948
,
RMSE
Testing
=
0.43
and
MAE
Testing
=
0.25
) as the most accurate among the three models considered, highlighting the potential of deep learning approaches for water quality parameter prediction.
Journal Article
Restoring geomorphic integrity in urban streams via mechanistically-based storm water management: minimizing excess sediment transport capacity
Stream channel erosion, enlargement, and habitat degradation are ubiquitous in urban watersheds with conventional stormwater management that increase channel-eroding flows relative to undeveloped watersheds. Hydrologic-based restoration aims to discharge a more natural flow regime via stormwater management interventions. Whether such interventions facilitate geomorphic recovery depends, in part, on the degree to which they restrict discharges that would otherwise contribute to channel erosion. Erosion potential (E), the ratio of post-developed to predeveloped sediment transport capacity, provides a simplified, mechanistic framework to quantify the relative influence of stormwater interventions on the geomorphic effectiveness of the flow regime. This paper compiles ca. five years of data following stormwater-based interventions in three distinct settings in the United States and Australia to demonstrate how the E framework can elucidate the role of hydrologic restoration interventions in facilitating trajectories of geomorphic recovery (or lack thereof). In a previously developed watershed with unstable streams, substantial reductions in E in one stream coincided with a trajectory of geomorphic recovery, whereas the control stream without E-reducing interventions exhibited continued instability. Furthermore, a stream downstream of a greenfield development that optimized their stormwater control measures to match the sediment transport capacity of the predeveloped regime (E = 1) was able to maintain a recovery trajectory in a legacy-impacted setting that is otherwise highly susceptible to hydromodification. Streambed material size, channel evolution stage, and the hydrogeomorphic setting also likely affect the level of E reduction necessary to promote geomorphic recovery, with coarser-grained and over-widened streams potentially needing less reduction than finer-grained and more entrenched channels. Although available space and funding will limit the ability to fully reduce E in previously developed watersheds, these case studies underscore the value of using stormwater control measures to maximize reductions in E if geomorphic stability is a goal of stormwater interventions.
Journal Article
Heavy metal contamination and environmental risk assessment: a case study of surface water in the Bahr Mouse stream, East Nile Delta, Egypt
Water, as an indispensable constituent of life, serves as the primary source of sustenance for all living things on Earth. The contamination of surface water with heavy metals poses a significant global health risk to humans, animals, and plants. Sharkiya Governorate, situated in the East Nile Delta region of Egypt, is particularly susceptible to surface water pollution due to various industrial, agricultural, and urban activities. The Bahr Mouse Stream, crucial for providing potable water and supporting irrigation activities in Sharkiya Governorate, caters to a population of approximately 7.7 million inhabitants. Unfortunately, this vital water source is exposed to many illegal encroachments that may cause pollution and deteriorate the water resource quality. In a comprehensive study conducted over two consecutive seasons (2019–2020), a total of 38 surface water samples were taken to assess the quantity of heavy metals in surface water destined for human consumption and other applications, supported by indices and statistics. The assessment utilized flame atomic absorption spectrophotometry to determine the concentration of key heavy metals including iron (Fe), manganese (Mn), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), nickel (Ni), cobalt (Co), and chromium (Cr). The calculated mean value of the Water Quality Index (WQI) was found to be 39.1 during the winter season and 28.05 during the summer season. This value suggests that the surface water maintains good quality and is suitable for drinking purposes. Furthermore, the analysis indicated that the concentrations of heavy metals in the study area were below the recommended limits set by the World Health Organization and fell within the safe threshold prescribed by Egyptian legislation. Despite the identification of localized instances of illegal activities in certain areas, such as unauthorized discharges, the findings affirm that the Bahr Mouse stream is devoid of heavy metal pollution. This underscores the importance of continued vigilance and regulatory enforcement to preserve the integrity of these vital water resources.
Journal Article
Navigating through space and time: A methodological approach to quantify spatiotemporal connectivity using stream flow data as a case study
The growing interest in combining spatial and temporal patterns in nature has been fostered by the current availability of high‐frequency measurements. However, we still lack a methodological framework to process and interpret spatiotemporal datasets into meaningful values, adaptable to different time windows and/or responding to different spatial structures. Here, we developed and tested a framework to evaluate spatiotemporal connectivity using two new measures: the spatiotemporal connectivity (STcon) and the spatiotemporal connectivity matrix (STconmat). To obtain these measures, we consider a set of spatially connected sites within a temporally dynamic network. These measures are calculated from a spatiotemporal matrix where spatial and temporal connections across sites are captured. These connections respond to a determined network structure, assign different values to these connections and generate different scenarios from which we obtain the spatiotemporal connectivity. We developed these measures by using a dataset of stream flow state spanning a 513‐day period obtained from data loggers installed in seven temporary streams. These measures allowed us to characterise connectivity among stream reaches and relate spatiotemporal patterns with macroinvertebrate community structure and composition. Spatiotemporal connectivity differed within and among streams, with STcon and STconmat capturing different hydrological patterns. Macroinvertebrate richness and diversity were higher in more spatiotemporally connected sites. Community dissimilarity was related to STconmat showing that more spatiotemporally connected sites had similar communities for active and passive dispersers. Interestingly, both groups were related to spatiotemporal connectivity patterns for some of the analysed scenarios, highlighting the relevance of spatiotemporal connectivity in dynamic systems. As we exemplified, the proposed framework can help to disentangle and quantify spatiotemporal dynamics or be applied in the conservation of dynamic systems such as temporary streams. However, the current framework is not limited to the temporal and spatial features of temporary streams. It can be extended to other ecosystems by including different time windows and/or consider different network structures to assess spatiotemporal patterns. Such spatiotemporal measures are especially relevant in a context of global change, with the spatiotemporal dynamics of ecosystems being heavily disrupted by human activities.
Journal Article
Early plant recruitment stages set the template for the development of vegetation patterns along a hydrological gradient
Summary Recruitment processes are critical components of a plant's life cycle. However, in comparison with later stages in the plant life cycle (e.g. competition among adults), relatively little is known about their contribution to the regulation of plant species distribution. Particularly, little is known about the individual contributions of the three main recruitment processes – germination, seedling survival and seedling growth – to community assembly, while quantitative information on these contributions is essential for a more mechanistic understanding of the regulation of plant species distribution and biodiversity. Riparian zones along streams provide a globally‐relevant case study for evaluating the importance of the different stages of plant recruitment. The natural hydrological gradients of stream riparian zones are currently being restored after a period of world‐wide habitat degradation. To identify how recruitment contributes to vegetation patterns and biodiversity in riparian zones, we carried out field experiments at restored lowland streams. We quantified the germination of introduced seeds, and survival and growth of introduced seedlings of 17 riparian plant species across a gradient from the stream channel to upland. The hydrological gradient of riparian zones acted as a strong environmental filter on all three recruitment processes, through imposing an abiotic limitation (excess water) at low elevations and a resource limitation (water shortage) at higher elevations. Other variables, such as soil organic matter content and nutrient availability, only affected recruitment marginally. Species‐specific patterns of environmental filtering initiated niche segregation along the riparian gradient during all three recruitment processes, but particularly during germination and seedling growth. These recruitment niches appeared strongly related to indicator values for adult distribution optima, suggesting that at least some riparian plant species may have evolutionary adaptations that promote recruitment under favourable hydrological conditions for adult growth and reproduction. Our results suggest that strong environmental filtering during germination and seedling growth plays an important role in determining later adult distributions, by forming the spatial template on which all subsequent processes operate. In addition to well‐known mechanisms, such as competitive exclusion at the adult stage, environmental filtering during early recruitment stages already strongly affect plant distribution and diversity. Lay Summary
Journal Article
Variability in the Shape of the Active Length–Streamflow Relationship in Temporary Streams: Insights From an Empirical Analysis
Non‐perennial stream reaches experience ceaseless shifts between flowing water and dry‐down, depending on the changes of the water availability in the upstream catchment. Consequently, the flowing network length L$L$and the catchment‐scale streamflow Q$Q$jointly evolve mirroring the temporal variations of landscape wetness. The resulting relation between L$L$and Q$Q$represents a powerful tool for monitoring, modeling and classifying non‐perennial rivers. However, a robust formal assessment of the L(Q)$L(Q)$shape across different catchments is still lacking. In this manuscript we analyze 45 case studies with joint empirical observations of L$L$and Q$Q$ , and test three models: the power law, the exponential, and the gamma functions. The empirical data confirms the presence of a high correlation between L$L$and Q$Q$in all case studies. However higher levels of noise emerge in higher frequency data sets. Furthermore, our analysis reveals three classes of L(Q)$L(Q)$shapes: generally increasing relations, relations with a right plateau, and s‐shaped relations. The results indicate that the gamma model produces the lowest errors and is able to describe all three shapes. In contrast, the power law model—while showing good performances—tends to overestimate the right plateaus. The exponential model, instead, proves to be too simple and often reaches the maximum network length for too low discharge values. The study provides a basis for better interpreting and modeling the joint variability of L$L$and Q$Q$ , providing clues about the sensitivity of the flowing length to streamflow changes in different geomorphic and climatic settings. Key Points The empirical relationship between flowing network length L$L$and discharge at the outlet Q$Q$is analyzed for 45 case studies Three qualitative classes of L(Q)$L(Q)$emerge: generally increasing relations, relations with a right plateau, and s‐shaped relations The gamma model shows the best performance in all case studies, while the power law tends to overestimate the right plateaus
Journal Article