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State of the World's Freshwater Ecosystems: Physical, Chemical, and Biological Changes
Abstract
Surface freshwaters — lakes, reservoirs, and rivers — are among the most extensively altered ecosystems on Earth. Transformations include changes in the morphology of rivers and lakes, hydrology, biogeochemistry of nutrients and toxic substances, ecosystem metabolism and the storage of carbon (C), loss of native species, expansion of invasive species, and disease emergence. Drivers are climate change, hydrologic flow modification, land-use change, chemical inputs, aquatic invasive species, and harvest. Drivers and responses interact, and their relationships must be disentangled to understand the causes and consequences of change as well as the correctives for adverse change in any given watershed. Beyond its importance in terms of drinking water, freshwater supports human well-being in many ways related to food and fiber production, hydration of other ecosystems used by humans, dilution and degradation of pollutants, and cultural values. A natural capital framework can be used to assess freshwater ecosystem services, competing uses for freshwaters, and the processes that underpin the long-term maintenance of freshwaters. Upper limits for human consumption of freshwaters have been proposed, and consumptive use may approach these limits by the mid-century.
... This water retention capacity-that is, the total amount of water that a system can absorb-is a fundamental yet underappreciated ecosystem function. A high water retention capacity has two profound consequences that provide benefits to people: (1) flood peaks are delayed and reduced (Schüler 2006;Collentine and Futter 2018); and (2) droughts develop more slowly and may have lower peaks in magnitude (Carpenter, Stanley, and Vander Zanden 2011;Dehnhardt et al. 2015;Lal 2020), because retained water is stored in the landscape for longer. Freshwaters also perform essential ecosystem processes, including filtering and storing water, and decomposing organic matter (Carpenter, Stanley, and Vander Zanden 2011;Dehnhardt et al. 2015). ...
... A high water retention capacity has two profound consequences that provide benefits to people: (1) flood peaks are delayed and reduced (Schüler 2006;Collentine and Futter 2018); and (2) droughts develop more slowly and may have lower peaks in magnitude (Carpenter, Stanley, and Vander Zanden 2011;Dehnhardt et al. 2015;Lal 2020), because retained water is stored in the landscape for longer. Freshwaters also perform essential ecosystem processes, including filtering and storing water, and decomposing organic matter (Carpenter, Stanley, and Vander Zanden 2011;Dehnhardt et al. 2015). Additionally, they offer vital ecosystem services that support human wellbeing, such as climate regulation, clean water provision, fish production, and recreational opportunities including fishing and swimming (Chiesura and De Groot 2003;Lynch et al. 2023). ...
As climatic extremity intensifies, a fundamental rethink is needed to promote the sustainable use of freshwater resources. Both floods and droughts, including water scarcity, are exacerbating declines in river biodiversity and ecosystem services, with consequences for both people and nature. Although this is a global challenge, densely populated regions such as Europe, East Asia and North-America, as well as the regions most affected by climate change, are particularly vulnerable. To date mitigation measures have mainly focused on individual, local-scale targets, often neglecting hydrological connectivity within catchments and interactions among hydrology, biodiversity, climate change and human wellbeing. A comprehensive approach is needed to improve water infiltration, retention and groundwater recharge, thereby mitigating the impacts of heavy rainfall and floods as well as droughts and water scarcity. We propose a holistic catchment-scale framework that combines mitigation measures including conventional civil engineering methods, nature-based solutions and biodiversity conservation actions. This framework integrates legislation, substantial funding and a governance structure that transcends administrative and discipline boundaries, enabling coordinated actions across multiple spatial and temporal scales. It necessitates the collaboration of local and regional stakeholders including local people with scientists and practitioners. A holistic vision for the sustainable management of freshwater resources could have synergistic effects that support biodiversity and mitigate climate change within functional ecosystems that deliver benefits to people.
... A complex benefit-threat relationship exists among freshwater, freshwater biota, agriculture, and humans. Freshwater, with its fish and ecosystem components, provides valuable ecological goods and services that benefit society by contributing to the economy (i.e., $1.7 trillion a year for rivers and lakes) [70] and enhancing the quality of life [71][72][73]. Human health benefits also accrue from aquatic ecosystems through experiencing nature and biodiversity [74]. ...
... Allocating water for multiple uses is challenging. A substantial amount of freshwater is used for agriculture (>70%) [73,80]. Agriculture provides jobs, but agriculture also adversely affects aquatic systems. ...
A common problem for interdisciplinary sustainability research is that scientists trained in different disciplines are often not rowing their boat effectively in the same direction. Sustainability tools can aid the implementation of this team-melding process. Here, our purpose is to illustrate our Multi-step Integrated graphical and structured discussion eXercise (MIX) tool that transforms diverse disciplinary experts into an interdisciplinary team. We use a visual puzzle-solving approach based on the blind men and the elephant metaphor (BMEM) because this story illustrates the shortcomings of siloed viewpoints and the need to integrate multiple perspectives. Our six-step MIX tool provides step-specific objectives, group activities, discussion questions, and learning outcomes. Activities promote experiential learning for team problem solving. The step-specific structured discussions are designed to get each individual to change their focus from their own discipline (i.e., an elephant trunk, tail, leg, or other isolated pieces of the whole animal) to the team’s interdisciplinary goal (i.e., the whole elephant or the entire multi-faceted problem). In our example proof of concept, we show that a narrow focus on only economic yield (trunk), ecological conservation (legs), or human values (tail) misrepresents the biologically involved sustainability problem (elephant) and blocks innovative solutions.
... In addition to global energy shortages, another critical challenge significantly impacts the Earth's inhabitants: the shortage of freshwater resources. Although water covers nearly two-thirds of the Earth's surface, freshwater accounts for only 3%, and even less is readily available for use, as only about 0.5% of the freshwater is accessible for practical use [5], [6]. ...
In the present study, the experimental investigation was conducted to evaluate the effect of adding recycled ground tire rubber in the basin of a single-slope solar still unit with a paddle wheel device to improve its performance. A single-slope solar still unit was used and investigated under the extreme climate of Basra in southern Iraq. Compared to the conventional type, the results of the developed solar still indicated that using recycled tire rubber granules increased the still's water productivity by approximately 95%. Using the paddle wheel device in the presence of recycled tire rubber granules increased water productivity to about 172%. The results also indicated that increasing the proportion of recycled granules of tire rubber impacts the unit's energy efficiency and water productivity. The energy efficiency achieved a maximum value of 38% for the improved solar still with 100% filling of recycled granules tire rubber and a paddle wheel device at a rotational speed of 30 rpm, while its value was reported to be about 46% at a rotational speed of 90 rpm. According to the energy and productivity analysis, these units can be reliable in remote areas and have good productivity compared to conventional solar stills.
... Since recent years, freshwaters such as rivers and streams have faced a dramatic increase in human-driven pressures and alterations, including changes in water flows and land use, invasive species introductions and chemical contaminations (Carpenter et al., 2011). For instance, the biological recovery of European streams is increasingly slowing since the last decade, notably in invertebrate communities downstream of croplands and urban areas (Haase et al., 2023). ...
... Freshwater, which constitutes only 2.5 % of the Earth's water, is essential for life on Earth (Carpenter et al., 2011). Groundwater is the largest accessible freshwater reserve and crucial for global water supply, especially in countries with significant withdrawals, such as Iran. ...
Study region: Tasht-Bakhtegan Basin, Iran Study focus: The main objectives of this study are to reconstruct and downscale GRACE data from a coarse resolution of 1-degree to a finer resolution of 1-km. This was accomplished using a robust and flexible multi-scale approach, leveraging machine learning algorithms, specifically random forest and LightGBM. The models were meticulously calibrated and thoroughly evaluated across various spatial scales. Additionally, the study examined the lag effects of influential covariates in the downscaling process, further enhancing model accuracy.New hydrological insights for the region The multi-scale calibration of the models provided new insights into the relationship between terrestrial water storage anomalies (TWSa) and various environmental and hydrological factors. It was found that precipitation and land surface temperature (LST) were the most influential covariates in the reconstruction and downscaling process. Specifically, precipitation with a two-month delay, LST with a three-month delay, and evapotranspiration with an eight-month delay exhibited the highest correlations with TWSa. These findings offer valuable insights into the temporal influence of key hydrological variables on TWSa within the region, shedding light on how delayed responses of precipitation, LST, and evapotranspiration affect groundwater storage. This enhances the understanding of the underlying dynamics governing hydrological variability in the study area.
... Small freshwater habitats, such as small floodplain ponds, are the hotspots of biodiversity (Fan et al., 2022). However, up to 90 % of floodplains having oxbow lakes and other floodplain ponds are functionally extinct in Europe (Dynesius and Nilsson, 1994;EEA, 2018;Stanford and Tockner, 2002), which threatens the biodiversity inhabiting floodplain habitats (Carpenter et al., 2011). On the other hand, ponds not dedicated to aquaculture and artificial habitats have the potential to support a much greater diversity of species than they currently do and may be particularly important for species that have lost their primary habitats, such as functional floodplains (Grill et al., 2019;Oertli and Parris, 2019;Parasiewicz et al., 2023). ...
Anthropogenic interventions are threatening small freshwater ecosystems and biodiversity, which continues to decline at an alarming rate. To address their biodiversity value, 210 small waterbodies in Czechia were sampled to determine how different habitat characteristics and anthropogenic-induced disturbances affect selected species community composition. Three types of habitats were chosen: ponds, pools and flooded quarries. The selected sites were sampled for fish with trap nets focussing on native crucian carp (Carassius carassius), sunbleak (Leucaspius delineatus) and invasive gibel carp (Carassius gibelio) and topmouth gudgeon (Pseudorasbora parva). The surface area of the water body, human population within 5 and 10 km radius, water transparency, elevation, macrophyte cover and the other existing fish species, newts and diving beetles were recorded. The two focal native fish species tended to co-occur with alpine newt (Ichthyosaura alpestris), great crested newt (Triturus cristatus), the smooth newt (Lissotriton vulgaris) and diving beetles (Dytiscus sp.), and were associated with sites with higher macrophyte cover. Densely inhabited areas were more likely to contain invasive fish species. Presence of invasive gibel carp and topmouth gudgeon was associated with low habitat quality. Flooded quarries supported fewer common species and had slightly higher diversity among the sampled sites. This study highlights the importance of small artificial water bodies as a secondary habitat for declining fauna associated primarily with floodplain ponds.
... Invasive species are among the most relevant causes of extinctions [87], particularly in aquatic ecosystems [88]. Their intentional or inadvertent introductions have become more frequent than ever in the last decades, likely due to the effects of globalization, in particular, due to the increase in international trade [14,89,90]. ...
We adopted a morphometric approach to provide statistical support for the description of two different morphotypes (I, reproductive, II, non-reproductive) firstly observed in Procambarus clarkii specimens caught in a population from Sardinia Island (western Mediterranean). The morphometric study was preceded by molecular taxonomic identification using the mitochondrial Cytochrome C Oxidase subunit I (COI) gene. The presence or absence of the pathogen Aphanomyces astaci, responsible for the plague, was also investigated using the ribosomal Internal Transcribed Spacer (ITS) marker. The estimation of the size at onset of maturity (SOM) was further performed in males. Finally, the population structure was examined. Our results confirmed the entirety of the individuals as P. clarkii, and the absence of the pathogen A. astaci. Morphological analysis revealed a significant correlation between chela and carapace lengths, while intra- and inter-sexual dimorphism in the chela length confirmed the occurrence of the two morphotypes. The SOM in males was established between 35.0 and 37.1 mm carapace length. Finally, the size-population structure showed a Gaussian distribution. The recognition of the two distinct morphotypes in the crayfish could be useful as an additional tool not only to identify the reproductive period of this invasive crustacean but also to enrich the guidelines for the correct taxonomic identification of the species.
... Freshwater ecosystems, particularly lacustrine environments are dynamic systems characterized by significant temporal and spatial variability (Grantham et al., 2019;Scott et al., 2012). These fluctuations present challenges to the evaluation of ecological health (Carpenter et al., 2011;Geist, 2011). Phytoplankton, as primary producers, are essential to energy transfer and nutrient cycling in aquatic food webs (Guo et al., 2016) and are highly responsive to environmental shifts (Reynolds, 1984). ...
Phytoplankton are vital components of freshwater ecosystems, serving as primary producers and ecological indicators of freshwater health. While substantial research has explored the dynamics and potential drivers of phytoplankton communities in freshwater lakes, the influence of altitude—a crucial geographic factor—remains unelucidated. In this study, we investigated 26 lakes located along the eastern section of the Hu Line (Heihe–Tengchong Line) from China, focusing on how altitudinal gradients shape phytoplankton communities. Our findings reveal that cyanobacteria increasingly dominate community abundance with rising altitude. However, this dominance results in a reduction of community diversity, as cyanobacteria outcompete other taxa, thereby narrowing the ecological niches available. Further analysis indicates that the effects of altitude are mediated primarily by dominant cyanobacteria, which are equipped with gas vesicles that provide an adaptive advantage under low atmospheric pressure conditions associated with higher altitudes. This physiological trait allows cyanobacteria to maintain buoyancy and occupy favorable niches in the water column, enhancing their proliferation at the expense of overall community diversity. The study underscores the critical role of altitude in modulating phytoplankton community structure through its direct influence on cyanobacteria. These findings contribute new insights into the ecological processes that regulate freshwater ecosystems across altitudinal gradients, and highlight the need for targeted management strategies in regions where cyanobacterial dominance (cyanobacterial blooms) may compromise water quality and biodiversity.
... The limited, yet diverse array of freshwater ecosystems in the region offer products and services that either directly or indirectly benefit humans, through avenues, such as fisheries, water purification, and flood avoidance. Because of this intrinsic relationship between humans and river ecosystems, particularly among the poor communities, declines in freshwater resources will have adverse effects on ecosystem services and livelihoods (Ayyad, 2003;Carpenter et al., 2011). ...
North Africa is generally a dry region characterized by arid to semiarid climate. The region is marked by severe water scarcity as well as a highly variable Mediterranean climate. As a result, only a handful of rivers are perennial in North Africa, with many of these being confined to the northern parts of Algeria, Morocco, and Tunisia. In this chapter, we briefly discuss rivers of the North African region, describing their surrounding climate, paleogeography and physiography, as well as the unique aquatic and riparian organisms associated with them. We further discuss threats faced by riverine ecosystems in this region, along with some of the conservation measures being implemented to ameliorate these challenges.
... Floodplains are remarkably biodiverse and productive habitats (Tockner and Stanford, 2002), mediating crucial ecological functions such as flood mitigation, nutrient retention and cycling (Reckendorfer et al., 2013). However, floodplains are increasingly impacted by excessive nitrogen (N) and phosphorus (P) loads from urbanisation and agricultural intensification (Carpenter et al., 2011), which promote algae growth and eutrophication (Banach et al., 2009). In riverfloodplain systems, the water quality is mediated by the dynamic lateral connectivity between the backwaters and the main river (Weigelhofer et al., 2015). ...
High loads of nutrients like phosphorus (P) persistently degrade water quality in floodplain waterbodies and cause eutrophication, i.e., elevated algae production. Despite continuous efforts to curb external nutrient loads entering freshwaters, internal P release from sediments frequently sustains eutrophication. Benthic microbial communities considerably impact nutrient turnover through the mineralisation of organic matter and may strongly affect P retention and release, which can be estimated via the P buffering potential. However, how these microbial processes shape the P buffering potential in hydrologically dynamic systems like floodplains is poorly understood. Here, we assessed the coupled effects of lateral hydrological connectivity, dissolved organic matter (DOM) quality and benthic microbial activity on the P buffering potential in a river-floodplain system. We examined seven sites in shallow floodplain waterbodies that were either connected or disconnected from the River Elbe (Magdeburg, Germany) after a summer contraction phase. Our findings show a significantly higher P buffering potential and thus, likely higher P release risk within connected sites, corroborated by distinct microbial community-level physiological profiles. The P buffering potential was positively correlated with more labile, low molecular weight DOM, increased autochthonous contribution, and a pronounced enzymatic degradation of hemicellulose (β-xylosidase activity). Our study underscores the pivotal role of hydrological connectivity, DOM quality and microbial enzyme activity in shaping sediment P buffering and potential P release in river-floodplain systems. Moreover, our results demonstrate the importance of critical yet often overlooked benthic sediment processes and microbe-organic matter interactions for P dynamics in floodplain waterbodies.
... Los CAC son elementales para el desarrollo y funcionamiento de nuestras ciudades (Lynch et al., 2016;Dörnhöfer y Oppelt, 2016), cumplen funciones importantes para los ecosistemas terrestres debido a que proveen de hábitat a un amplio rango de especies y son un componente esencial del ciclo biogeoquímico del agua, carbono y nitrógeno (Carpenter et al., 2011;Moss, 2012). Debido a esto es importante implementar programas de caracterización y monitoreo de FA que nos permitan describir su frecuencia e intensidad. ...
Resumen: El lago-cráter de Santa María del Oro en el Estado de Nayarit, México, presenta Florecimientos Algales (FA) de manera cíclica anual. El florecimiento y posterior decaimiento de estas poblaciones de algas crea cambios de color en el agua, generalmente en la primera mitad del año. Este trabajo evalúa algoritmos de clasificación supervisada que permitan identificar estos cambios usando datos de los productos MOD09GQ y MYD09GQ del sensor MODIS en el período de enero 2003 a diciembre 2020. A partir de una revisión de FA registrados en la literatura y análisis estadísticos de gráficos de dispersión, se construyó una base de datos de información espectral y etiquetas del estado de color del lago para evaluar diferentes algoritmos de clasificación. El mejor clasificador fue Random Forest con una precisión de 83,3%. El análisis temporal y la evaluación espacial de la incidencia de los florecimientos mostraron que mayo, abril y marzo son los meses con mayor presencia de cambios de color en el lago relacionados a FA. En el análisis espacial se encontró que la mayor incidencia de florecimientos se da en la región sureste del lago y las mayores cantidades de eventos ocurrieron en los años 2011, 2008 y 2012, respectivamente. Se determina la influencia del fenómeno El Niño-Oscilación del Sur (ENSO) en la incidencia de FA en el lago-cráter debido al patrón temporal entre las anomalías en los FA y el índice multivariado de El Niño-Oscilación del Sur, donde el mayor número de eventos de FA se presentaron en las fases frías del ENSO. Palabras clave: MODIS, algoritmos de clasificación de aprendizaje automático, florecimientos algales nocivos, lago turquesa. Abstract: The crater lake of Santa María del Oro in Nayarit State presents Algal Blooms (AB) in a cyclical annual manner. The blooming and subsequent decline of these populations creates color changes in the water, generally
... Understanding the sources and behavior of pollutants is essential for developing effective pollution control strategies, implementing regulatory measures, and promoting sustainable practices to safeguard environmental quality and human well-being. Collaboration between scientists, policymakers, industries, and communities is critical for addressing pollution challenges and achieving environmental sustainability (Carpenter et al., 2011). ...
It gives an insightful approach to the concept of pH, Acids and bases. The fundamental concept of acid and alkaline solutions, relationship between acids and bases, their pH of the various regions in the body, pH in disease and disorders and the application of pH in pharmacy, medicine and other fields.
... The dam wall causes the river's velocity to decrease, creating a lacustrine system in the constructed reservoir. The physical alteration caused by damming results in chemical alterations inside the reservoir, affecting the chemical and physical characteristics of the water and having an ecological effect on rivers downstream and the wetlands that are linked with them [148]. The physical, chemical, and biological consequences of dam construction on water quality have received the most research the summary of these consequences is illustrated in Fig. 7. ...
... Understanding the sources and behavior of pollutants is essential for developing effective pollution control strategies, implementing regulatory measures, and promoting sustainable practices to safeguard environmental quality and human well-being. Collaboration between scientists, policymakers, industries, and communities is critical for addressing pollution challenges and achieving environmental sustainability (Carpenter et al., 2011). ...
The ability to speed up chemical processes without consuming itself is known as catalysis, and it is essential to many scientific and industrial uses. This chapter presents an in-depth analysis of catalysis, starting with an overview of its basic concepts and workings. It highlights significant discoveries and technical developments while examining the historical viewpoints and significant turning points that have defined the field. The principles of catalysis are explained, including surface chemistry, reaction kinetics, and the function of catalysts in increasing the rate of reaction and selectivity. The latest advancements in the study of materials, nanostructures, and customized surface functions that maximize catalytic performance are the main topics of discussion while examining recent advances in catalyst design. Computational method advances are investigated as essential instruments for catalyst design and discovery, utilizing quantum physics and simulations of molecules to forecast. Zeolites, metallic-organic frameworks (MOFs), and catalysts with one atom are examples of novel catalytic structures and materials that are explored for their special qualities and potential uses in a variety of sectors. The chapter explores catalysis for environmentally friendly chemistry, with a focus on ecologically friendly techniques, renewable feedstocks, and green catalytic processes. Applications of catalysts in energy conversion, such as fuel cells, photocatalysis, and hydrogen production, demonstrate how important catalysts are to the development of sustainable energy solutions. To address new areas like bio catalysis, artificial based on intelligence catalyst development, and dynamic catalytic systems, recent trends and potential futures in catalysis are examined. This comprehensive evaluation of catalysis's prospects and challenges—such as deactivation of catalysts, scalability, and economic viability—offers ideas on removing obstacles and promoting innovation in the sector.
... On the other hand, aquatic ecosystems are also the most altered ecosystems on earth, experiencing huge impacts in response to global changes (Carpenter et al. 2011). The degradation of these ecosystems leads to a significant loss of biodiversity, which results in a decline in the ecosystem services provided by aquatic ecosystems (IPBES 2019; Jackson et al. 2016;Nõges et al. 2016). ...
The continuous increase of anthropogenic activities reinforces their stress on aquatic ecosystems (from continental to marine ecosystems) that are the most altered ecosystems on Earth. To evaluate the risk of ecosystem decline toward human alterations, the concept of “ecological vulnerability” was developed to help managers to prioritize conservation actions. Various definitions of vulnerability and its components were used, but this concept is often centered on the intersection of three components: sensitivity, exposition, and adaptive capacity. The aim of this study was through a review of the scientific literature of the last 10 years, first to assess the goals of the use of the concept of vulnerability in aquatic ecology: for which pressure (e.g., climate change, predation) and organism, on which level of organization (individuals, species, …). The second objective, was to address the methods developed to assess vulnerability: which components were considered, which metrics were used, the scoring process… Fish were the organisms the most frequently concerned and the number of publications decreased with the increasing complexity of biodiversity studied (from populations to multitrophic organizations). Climate change was the main stressor for which vulnerability was assessed. Vulnerability was commonly defined as being highly sensitive, highly exposed and lowly adaptable even if adaptive capacity was rarely addressed. This study showed an interest in the concept of vulnerability to protect aquatic ecosystems. Nonetheless, to better evaluate their risk of biodiversity loss, we should consider vulnerability at a higher level of organization and encompass the adaptive capacity of the biota.
... Furthermore, the transport mechanisms relocating freshwater species are advancing, including improved trade routes and the threat of unregulated e-commerce [150]. Thus, freshwaters are experiencing widespread species declines and losses in biodiversity [24] and the introduction of non-native species is a key factor driving these impacts [153]. ...
Background
This review compiles and synthesises the existing information concerning non-native poeciliid introductions to Africa. The recent upsurge in research on invasive poeciliids has revealed their widespread occurrence in Africa.
Results
Within the 87 relevant articles, 74% reported on the presence of Gambusia spp., 33% on P. reticulata , 19% on X. hellerii , 11% on X. maculatus , and 5% on other ornamental poeciliids. Overall, poeciliids have been documented as introduced to 25 different countries in Africa. With Gambusia spp. being introduced to 16 countries and P. reticulata to 19 countries. Our results are representative of the current state of research on invasive poeciliids in Africa. There was a concentration of studies in South Africa, with limited research elsewhere. Current distribution data is relatively patchy, although widespread surveys of multiple river systems in Morocco and South Africa, confirmed widespread and abundant established poeciliid populations. The ecological impacts of invasive poeciliids in Africa remain understudied but evidence indicates deleterious effects on native fish, invertebrates, and amphibians, many of which are critically endangered or endemic.
Conclusion
Current research is limited in reporting from certain countries and ecological impacts. An increased effort to monitor species composition in vulnerable waterbodies, especially in the many African countries where invasive poeciliids are reported, should be completed to reveal further established populations. Future research should prioritise quantifying the ecological impacts of invasive poeciliids in the field and identifying both vulnerable and resistant native ecosystems to guide future management decisions.
... Understanding the sources and behavior of pollutants is essential for developing effective pollution control strategies, implementing regulatory measures, and promoting sustainable practices to safeguard environmental quality and human well-being. Collaboration between scientists, policymakers, industries, and communities is critical for addressing pollution challenges and achieving environmental sustainability (Carpenter et al., 2011). ...
... Understanding the sources and behavior of pollutants is essential for developing effective pollution control strategies, implementing regulatory measures, and promoting sustainable practices to safeguard environmental quality and human well-being. Collaboration between scientists, policymakers, industries, and communities is critical for addressing pollution challenges and achieving environmental sustainability (Carpenter et al., 2011). ...
The chapter gives a comprehensive insight into medicinal chemistry and the treatment of diseases. It also give a breakdown of what drug design and development
... Collectively, these stressors contribute to the global deterioration of freshwater ecosystems 1 . Whereas each stressor independently impacts freshwater biodiversity and ecosystem function 4,5 , real-world aquatic systems almost always face simultaneous exposure to multiple anthropogenic stressors. These stressors can act independently or additively, whereby their individual effects are combined to have cumulative negative impacts. ...
... Today, more than 1.2 million obstacles are present on European rivers (Belletti et al. 2020). These structures modify the hydromorphology of the river and the substrate movement dynamics, thereby impacting the quality of habitats (Baudoin et al. 2015;Carpenter, Stanley, and Vander Zanden 2011), as well as altering the migratory movements of fish (De Leeuw and Winter 2008;Ovidio et al. 2021). ...
The installation of fishways is the most common method to restore connectivity and allow fish to carry out their life cycle. However, the performance and efficiency of fishways are still highly variable, particularly for freshwater potamodromous species. We aimed to determine the passage efficiency of a fishway installed in 2021 downstream of the Coo waterfall in Belgium to allow upstream migration and crossing of the 11.8 m height. We double‐marked 38 individuals (RFID tag and radio transmitter) belonging to three species ( Barbus barbus , Salmo trutta and Thymallus thymallus ) from upstream and then released them 1.2 km downstream of the waterfall. A total of five automatic detection antennas were installed downstream of the waterfall and within the fishway, and the individuals were tracked with manual radio telemetry. We used several behavioural metrics to assess efficiency and attractiveness. The results indicate a lack of attractiveness of the fishway (overall rate of attraction < 25%). There was a higher detections at the waterfall (26 detections) than at the restitution channel (12 detections), where the entrance of the fishway was located. For individuals that reached the fishway entrance, the fishway efficiency was 12.5% for barbel and 6.3% for trout, with an average fishway entrance searching delay of 25 days for barbel. The lack of attractiveness led to numerous back‐and‐forth movements by individuals to find the entrance and the search for a substitute spawning habitat downstream. Our results indicate the need to improve the attractiveness of the fishway, in particular by improving the attraction flow.
... However, these ecosystems are threatened by pollution, habitat alteration, species introduction, and climate change. Conservation and restoration efforts are vital to protect freshwater resources and promote sustainability (Aylward et al. 2005;Carpenter et al. 2011;Allan et al. 2021). Sapang Balen, also known as Dolores River, is one such freshwater ecosystem facing these challenges. ...
Scarcity of freshwater is a significant global threat, particularly in ecosystems like rivers, which are crucial for biodiversity, drinking water, and community sustenance. This study evaluates the ecological health of the Sapang Balen River in Mabalacat City, Pampanga, Philippines, by examining plant species, solid waste accumulation, heavy metals, coliform counts, and physicochemical parameters. Field measurements and laboratory analyses revealed low biodiversity in the river, characterized by many fast-growing and invasive plants that threaten ecosystem balance. Water quality assessments indicate alarmingly high levels of microbial contamination, with coli-
form counts significantly exceeding safe limits, likely due to urbanization and domestic waste. Despite these challenges, ongoing remediation efforts, such as bioflocculants, filtration systems, and water revetments, show promise for improving water quality. The study highlights the importance of continuous monitoring and adaptive management to restore and sustain the health of the Sapang Balen freshwater ecosystem.
... Inland freshwater habitats are rich in biodiversity yet are highly susceptible to anthropogenic disturbances (Paul and Meyer 2001;Dudgeon et al. 2006;Carpenter, Stanley, and Vander Zanden 2011). Biodiversity studies in aquatic ecosystems are restricted to a few taxa (commonly fish and birds), often leading to biased inferences about ecosystem health and functioning (Carneiro et al. 2019). ...
We studied freshwater gastropod fauna in a heavily urbanized region in tropical India, across a range of habitat types. A total of 16 species were found from a two-year survey, which is a decline of 27% compared to studies completed in the 1970s. Planorbidae was the most species rich family in the collection, with five species. Racesina luteola (Lamarck, 1822) was the most commonly occurring species in the collection. Three non-native species, including Pomacea diffusa (Blume, 1957), are also reported. Habitat type influenced species occurrences, although lentic and lotic
habitats were largely similar in their fauna. Many species reported previously were missing from the current survey, along with an increased incidence of non-native species which were absent from earlier reports. This decline in species richness, particularly of native species, alongside an increased incidence and spread of non-native species in the region, highlights the impact of urbanization on the freshwater gastropod community.
... Managing freshwater recreational fisheries is increasingly challenging as natural recruitment of many species has declined across their range (Bethke and Staples 2015;Rypel et al. 2018;Sass, Feiner, and Shaw 2021;Van Zuiden and Sharma 2016) due to factors such as climate change (G. J. ; J. F. , introductions or increases of unwanted species (Carpenter, Stanley, and Vander Zanden 2011;Hansen et al. 2017) and water quality degradation (Feiner and Höök 2015;Feiner et al. 2022). In response, managers have initiated more frequent supplemental stocking programs (Grausgruber and Weber 2020;Rahel 2022). ...
Fish stocking continues to be an important and often‐used tool in fisheries management. Mortality of fish may be high in the first few days after stocking due to predation and a lack of appropriate food and habitat. The objective of this study was to develop a conceptual model that may identify stocking locations that can help improve the survival of stocked fish. We identified three factors—predator risk, zooplankton (food) availability and measures of habitat that could be important to the survival of stocked Walleye (Sander vitreus) and White Bass (Morone chrysops) fingerlings in Lake McConaughy, Nebraska. The spatial distribution of these factors was used to create a predictive surface to identify those stocking locations hypothesised to lead to higher survival. Final stocking maps identified the best 12.8% and 13.9% of the predicted area of Lake McConaughy for stocking Walleye and White Bass, respectively. Both maps predicted that the best locations were along the south‐central shoreline of Lake McConaughy. The maps for both species were interestingly similar. These results are likely due to the similarities in predators consuming the stocked species and the zooplankton consumed by fingerlings of both species. Habitat availability may be less important, or other aspects of habitat may need to be considered. Identifying the best locations for stocking based on predation risk and the availability of food and habitat could increase the survival of stocked fishes and help managers reach population objectives.
... Overharvest and other negative impacts on fisheries can result from lack of collaboration between or among nations (Pikitch et al. 2005;Carpenter, Stanley, and Vander Zanden 2011). Among United States management agencies, collaboration is hindered by a lack of standardization in surveys, which precludes data sharing (Smith and Blackwell 2019) and interstate fisheries management. ...
Regional factors correlated to recruitment of black bass (largemouth bass; Micropterus nigricans and smallmouth bass; Micropterus dolomieu), two important fishes, are rarely studied, despite the importance of recruitment variation in influencing fish populations. We sought to identify factors that drove variation in age-0 and age-1 black bass abundance. Age-0 or age-1 black bass catch per unit effort (CPUE) in reservoirs in Kansas and Illinois, USA was positively correlated with local short-term (i.e., mean April precipitation) environmental variables. In contrast, age-0 or age-1 black bass CPUE was generally negatively correlated with long-term environmental variables and river regulation metrics (i.e., reservoir elevation) in the Mississippi and Missouri river reservoirs. Our findings highlight that consideration of spatiotemporal scale is important when managing black bass populations.
... Toxic chemicals, organic waste, and additional nutrients can cause changes in the physical and chemical properties of water, altering ecosystem dynamics. This can lead to excessive algae growth, oxygen depletion in the water, and habitat loss for certain species (Carpenter et al., 2011). Coastal areas also experience the impacts of climate change, especially through sea-level rise. ...
Sewage pollution originating from the activities of shrimp farming companies in the Pasir Kuning Beach area raises serious concerns about its impact that damages the environment and disrupts the balance of the ecosystem. This research aims to understand and analyze the inclusiveness of social capital in local communities as an effort to prevent sewage pollution. Using a qualitative approach, this research conducted in-depth interviews with community members in the Pasir Kuning Beach Area. Respondents were selected based on criteria that ensured a balanced representation of various community groups, and secondary data was used to provide a broader context. The research findings highlight the central role of social capital in shaping relationships, trust, and cooperation among communities. The implications include developing more effective sewage pollution prevention strategies and providing a foundation for understanding community contributions to coastal ecosystem conservation. The focus on social capital inclusivity as a catalyst for positive change demonstrates the determination of local communities to overcome the negative impacts of shrimp farming activities. In the context of Bangka Belitung, which is affected by the mining sector, this research is significant in efforts to reduce environmental damage. It is hoped that these findings provide valuable insights for stakeholders in formulating sustainable solutions that support the ecology and well-being of local communities in the future.
... Phosphorus (P) loss from agriculture fields and watersheds continues to negatively impact water quality at local and regional scales (Breitburg et al., 2018). In the Midwestern United States, nitrogen (N) and phosphorus (P) transport from row-crop production of corn (Zea mays L.) and soybean (Glycine max L.) results in degradation of water bodies causing eutrophication, coastal hypoxia, harmful algal blooms, and biodiversity losses (Carpenter et al., 2011). Long-term application of P fertilizers can increase the labile P content in cultivated soils resulting in increased potential of P loss through surface runoff (Jarvie et al., 2017). ...
Winter cover crops (CCs) have the potential to reduce phosphorus (P) loss by temporarily fixing P into CC biomass. A field experiment with no‐tillage (NT) and conventional tillage (CT) was used to study the ability of different CC species planted after corn (Zea mays L.) and soybean (Glycine max L.) harvests to reduce the P availability in soil solution. The effect of three crop rotations (corn–no CC–soybean–no CC [C–S], corn–cereal rye (Secale cereale)–soybean–hairy vetch (Vicia villosa) [C–R–S–HV], corn–cereal rye–soybean–oats (Avena sativa)+ radish (Raphanus sativus L.) [C–R–S–OR]) and two tillage (NT and CT) treatments was determined on soil available P and soil solution P content through pan (A horizon) and tension (100‐cm depth) cup lysimeters. The experiment was set up as a randomized complete block design with tillage as a split factor with three replicates. Over the study period, incorporating hairy vetch in C–R–S–HV rotation reduced the Mehlich‐3 P content in soil by 26%–29% compared to the C–S and C–R–S–OR rotation. Both CC rotations (C–R–S–HV and C–R–S–OR) were effective in reducing dissolved reactive P (DRP) concentration in pan and tension cup lysimeters compared to the C–S in both CT and NT systems. However, these results varied with CC species grown and seasonal variability in precipitation. A significantly lower DRP load with crop rotation and tillage treatments was observed mainly during the CC growing season. During the study period, crop rotations with reduced labile soil P content and DRP loss were ranked in an order of C–R–S–HV > C–R–S–OR > C–S. Overall, this study showed that CCs have the potential in both CT and NT systems to significantly reduce P in soil and soil solution, and these effects are resilient to a wide range of precipitation conditions.
... Urbanization and climate change cause pollution in fresh water ecosystems by liquid and solid water produced by human settlements and industrial activates. [Carpenter et al., 2011] The sources of water that are safe to drink or to use for preparation of food is known as clean water or drinking water. Fig. 1.1, shows the globally available raw water that can be utilized as clean water sources. ...
Abstract
One of the tools that are used to solve problems of surface water pollution is modelling of variations which take place in surface water and associated water quality changes. In the last thirty years a rapid development of mathematical modelling of water resources quality has been observed. A number of computer models have been designed which are successfully applied in practice in many countries in worldwide. This work presents an overview of mathematical models for assessment of water quality of Tigress River using Minitab 19 program, through identification of toxic contaminants approaching to some water treatment plant in Baghdad city.
Physical and chemical data have been adopted from Government departments and previous studies, for the purpose of analyzing them and studying the effect of physical dependent variables on toxicological variables. The most closely related variables are implemented to obtain high quality results. The elements lead Pb, cadmium Cd, and manganese Mn were taken as toxic variables due to the presence of good correlations with physical variables, as well as explaining the behavior of other toxic elements due to the relationship with them. This data was obtained from the correlation matrix, processing and mining data.
Multiple Linear Regression (MLR) methods were used to derive the mathematical model for toxic compounds of Tigris River in Baghdad city. The
equations were of high reliability, reaching 83.78%, 96.36% and 90.85% for Cadmium, Lead and Manganese respectively, due to the selection of the highest correlated variables.
These equations explain the toxic behavior of raw water of Tigris River approaching to Al Karama, Al Qadisiya, Al Wathbah and Al Dawrah water treatment plants with in Baghdad city by using easy measurable physical parameters. These equations also provide a future forecast of the behavior of the toxic pollutants in the study area.
... High nutrient loading is often a consequence of increased human activities, we therefore hypothesized its association with PPCPs occurrence [64,65]. Indeed, DOC were found as an important predictor for 8 out of 11 detected PPCPs; and the other 3 PPCPs were significantly correlated with either N, P or S content (Table 3). ...
Pharmaceuticals and personal care products (PPCPs) are unintentionally released into the environment from treated and untreated wastewater, agricultural runoff, and stormwater, and enter drinking water treatment plants (DWTPs). However, very little is known about the occurrence of PPCPs and their removal effectiveness during the drinking water treatment processes (conventional or advanced treatment) in multiple DWTPs, especially within the same geographical area. To address this important knowledge gap, source and finished drinking water samples were collected monthly from May to September in 2018 and 2019 from four DWTPs in Northern Ohio, USA. The total and individual PPCP concentrations varied among DWTPs and sampling dates in both source and finished water. Despite the site and time differences, caffeine and 17-beta-estradiol were detected at a frequency of 100% in all four DWTPs on all dates, while acetaminophen, estrone and nicotine consistently were not detected. Significant correlations were identified between the source water PPCPs and some environmental variables, such as dissolved organic carbon (DOC), temperature and pH. The PPCP removal efficiency from finished water samples varied depending on DWTP (61.2–84.2%), sampling month (28.3–89.7%), and different PPCP compounds (31.2% and 99.3%). Overall, this study demonstrated that PPCPs were consistently present in low concentrations (ng/L) in the freshwater systems; conventional treatment methods could only partially mitigate PPCP contaminants, while advanced techniques, such as UV-peroxide treatment, provided better removal efficiencies. PPCP removal also depended on the season, with summer demonstrating the highest removal in all four treatment plants.
... Agriculture is known to be a major source of N and P, and nutrient runoff from agricultural practice is an underlying cause of eutrophication in many catchments (Carpenter et al., 2011;Moss, 2008). N and P reach streams through wash-off and leaching of nutrients from fertiliser and manure applications to arable landscapes, and through soil disturbance and sediment runoff due to land management practices and livestock grazing (Nisbet et al., 2022). ...
... Regarding the types of human activity, our findings show that reservoirs and multiple activities decrease functional richness, and deforestation decreases functional regularity in tropical areas while fragmentation decreases functional richness on temperate area. The enormous changes that reservoirs cause in the environment are well documented in the literature (Agostinho et al., 2008;Baxter, 1977;Carpenter et al., 2011;Rosenberg et al., 1995;Soukhaphon et al., 2021;Wu et al., 2019). Reservoirs change the water flow dynamics, turning a lotic environment into lentic; thus, the reduced and human-controlled flow due to the dam operation jeopardizes the aquatic-terrestrial interactions and the nutrient cycling (Baxter, 1977;Junk & Mello, 1990). ...
Freshwater environments are intertwined with human activities and the consequence has been environmental degradation and biodiversity loss. Fish provide key ecological and economic benefits, and fish abundance and diversity can be affected by human activities resulting in functional diversity (FD) changes that might scale up to ecosystem impacts. Changes in FD can be expressed by quantifying its three main FD components temporally and/or spatially: richness, regularity, and divergence. There is no consensus about how human activities affect the main components of FD. In addition, human activities might affect the functional diversity of communities differently in temperate and tropical regions because of differences in the regional pools and the distribution of functional traits. Here, using a meta-analytical approach, we assess how different human activities (e.g.., deforestation, invasion, reservoirs) in freshwater systems affect FD components in fish communities. We compiled information from 2012 to 2023, and we found highly idiosyncratic patterns globally, but consistent loss of functional richness and regularity in face of human activities in the tropics. This idiosyncrasy could be related to high environmental heterogeneity or the multiple ways in which communities can be affected by human activities, or the distribution of functional uniqueness and redundancy. The reduction of functional diversity is concerning since human activities are removing specific functions from natural environments and results in the dominance of traits related to generalist ecological strategies. Despite the general patterns of reduction, local features are determinants on how the community will answer to human activity and therefore we highlight the importance of understanding the environment and fauna at the local scale, and the mechanisms by which each activity might affect FD.
... Physical, chemical, and biological characteristics are necessary for a healthy aquatic ecosystem (Carpenter et al., 2011). The nature of water in any biological system gives pivotal data about the accessible assets for supporting life in that environment (Thirupathaiah et al., 2012;Guerry et al., 2015). ...
Surma River, which flows through Sylhet, is an essential source of aquatic resources and water resources in the region. But expansion of urban region has also increased the pollutants in the river’s water which has immersed as a huge problem for Surma’s physiochemical properties. This study has been focused on evaluating the impact of water pollution on these physiochemical properties of Surma River’s water over six months in 2023 by concentrating on its advantages and cons on fish habitat. Using YSI Pro DSS Multi parameter, water samples were collected from four different stations along the river, including Lamakazi (Station 1), Kanishail Ghat (S-2), Sheikhpara (S-3), and Kazir Bazar (S-4) where every station contains 4 Collection points. Key parameters, such as temperature, pH, dissolved oxygen (DO), total dissolved solids (TDS), and nitrate levels, were analyzed. A statistical model was then applied to assess the importance of seasonal variations and their influence on these water quality parameters at the different stations. The results show seasonal variations, with higher temperatures and lower DO levels recorded during the monsoon season, particularly at Station 4, suggesting potential stress on fish populations. The study emphasizes the importance of simultaneous monitoring and pollution management to safeguard the aquatic ecosystem and ensure the sustainability of the river's resources. Future research may focus on the long-term effects of pollution on fish populations and the implementation of effective conservation strategies.
... Climate change is one of the biggest threats to lakes (Carpenter et al., 2011). Elevated global temperatures due to climate change enhance lake evaporation worldwide (Wang et al., 2018). ...
Thermal stratification can cause various water quality issues in large water bodies. To address this, a new wind‐powered artificial mixing system is designed and experimentally tested for various Savonius rotor combinations (three‐stage and four‐stage rotors). These turbines directly utilize wind energy to draw air into the water column for aeration, bypassing the need for electrical conversion. The rotor performances were tested in terms of power and torque coefficients. Additionally, these rotors were tested for artificial mixing efficiencies in a specially designed water tank that can mimic thermal stratification typically observed in an actual water supply reservoir. Among the rotors, the three‐stage rotor with a 60° phase shift was found to exhibit superior power and torque coefficients, achieving a power efficiency value of 0.14. As for the mixing efficiency, the four‐stage rotor with a 45° phase shift excelled in mixing efficiency, reaching 95%.
Practitioner Points
A new wind‐powered artificial mixing system is designed and tested for various Savonius rotor combinations.
While keeping the total rotor height constant, the three‐stage Savonius rotor class shows superior performance against the four‐stage Savonius rotor class in terms of power and torque efficiency.
Apart from the rotor performance results, the four‐stage Savonius rotors show greater artificial mixing efficiency than the three‐stage Savonius rotors.
Single‐pump/diffuser artificial destratification system exhibits better mixing efficiency than multiple‐pump/diffuser systems.
... The major threats to freshwater biodiversity are pollution and eutrophication (Dudgeon et al. 2006), habitat conversion (Moyle & Light 1996, Cambray 2003, removal of geographical barriers (Semenchenko et al. 2011, Rabitsh et al. 2013 and biological invasions (Gozlan et al. 2010;Souza et al. 2022). Their interaction with global climate change impacts such as increased temperature (Carpenter et al. 2011, Rolls et al. 2017, Osland et al. 2021) and altered hydrological regimes (Barbarossa 2021) will create new opportunities for successful future invasions of introduced species (Carosi et al. 2023). ...
... Disrupted seasonal patterns have resulted in positive feedback loops with warmer winter temperatures and (or) shorter periods of winter ice coverage, earlier and more rapid spring water warming, warmer and prolonged summer growing seasons and stratification periods, and delayed autumn cooling (Sharma et al., 2019;Maberly et al., 2020;Woolway et al., 2021;Woolway, 2023). These changes in seasonal temperatures and lake mixing have modified lake ecosystem productivity (O'Reilly et al., 2015;Yankova et al., 2017), which can have large impacts on ecosystem structure and function (Carpenter et al., 2011;Bhagowati and Ahamad, 2019). ...
Fishes in northern latitude lakes are at risk from climate-induced warming because the seasonality in water temperature is degrading, which can change ecosystem properties and the phenology of life-history events. Temperature-dependent embryo development models were developed for a group of cold, stenothermic fishes (Salmonidae Coregoninae) to assess the potential impacts of climate-induced changes in water temperature on cisco (Coregonus artedi) from two populations in Lake Superior (Apostle Islands [USA] and Thunder Bay [Canada]) and one in Lake Ontario (USA), vendace (C. albula) in Lake Southern Konnevesi (Finland), and European whitefish (C. lavaretus) in lakes Southern Konnevesi, Constance (Germany), Geneva (France), and Annecy (France). Water temperatures for each study group were simulated and changes in reproductive phenology across historic (1900-2006) and three future climatic-warming scenarios (2007-2099) were investigated. Models predicted that increases in water temperatures are likely to cause delayed spawning, shorter embryo incubation durations, and earlier larval hatching. Relative changes increased as warming scenarios increased in severity and were higher for littoral as compared to pelagic populations. Our simulations demonstrated that slower cooling in the autumn and (or) more rapid warming in spring can translate into substantial changes in the reproductive phenology of coregonines among our study groups. We expect that the changes in reproductive phenology predicted by our models, in the absence of thermal or behavioral adaptation, will have negative implications for population sustainability.
... Irrigated agriculture is the largest water user in the world, and irrigation water use accounts for approximately 70% of global freshwater withdrawals (Carpenter, Stanley, and Vander Zanden 2011). Climate change and increasing human water demand, combined with traditional wasteful irrigation practices, are exacerbating water use conflicts, even in traditionally water-rich countries. ...
Climate change has emerged as a key threat to biodiversity, leading to broad-scale shifts in distributions of marine and terrestrial species as they attempt to track thermally suitable habitat. By contrast, our understanding of climate responses of freshwater species is relatively undeveloped, limiting our knowledge of whether projected warming will lead to freshwater biodiversity loss. Here, we linked a multicontinental database of riverine fish population abundance time series collected from 1958 to 2019 to temperature data from the same period. Across the sampled localities, waters warmed by 0.21 °C per decade (annual maximum of monthly temperatures). We tested whether fish responded to this change by i) increasing abundance at the cooler poleward limit of species distributions—predicted if warming has opened new opportunities—and ii) decreasing abundance toward the equatorward limit of distributions—predicted if temperatures have exceeded tolerance thresholds. We found that observed population trends were consistent with both of these expected patterns from climatic warming and that the trends were more pronounced in time series covering the longer time periods of 30+ y. The responses consistent with climate change were most evident in species with larger body sizes, higher trophic levels, river–sea migratory behavior, and more widespread distributions. Moreover, positive abundance responses to warming were more likely at higher altitudes where conditions tend to be cooler. These findings indicate that projected future warming will likely lead to widespread shifts in riverine community structure, including abundance declines at the trailing edge of species distributions.
The people of New York have long benefited from the state's diversity of ecosystems, which range from coastal shorelines and wetlands to extensive forests and mountaintop alpine habitat, and from lakes and rivers to greenspaces in heavily populated urban areas. These ecosystems provide key services such as food, water, forest products, flood prevention, carbon storage, climate moderation, recreational opportunities, and other cultural services. This chapter examines how changes in climatic conditions across the state are affecting different types of ecosystems and the services they provide, and considers likely future impacts of projected climate change. The chapter emphasizes how climate change is increasing the vulnerability of ecosystems to existing stressors, such as habitat fragmentation and invasive species, and highlights opportunities for New Yorkers to adapt and build resilience.
Climate change is affecting freshwater systems, leading to increased water temperatures, which is posing a threat to freshwater ecological communities. In the Nechako River, British Columbia, a water management program has been in place since the 1980s to maintain water temperatures at 20 °C during the migration of adult Sockeye salmon. However, the program's effectiveness in mitigating the impacts of climate change on resident species like Chinook salmon's thermal exposure is uncertain. In this study, we utilised the CEQUEAU hydrological model and life stage-specific physiological data to evaluate the consequences of the current program on Chinook salmon's thermal exposure under two contrasting climate change and socio-economic scenarios (SSP2-4.5 and SSP5-8.5). The results indicate that the thermal exposure risk is projected to be above the optimal threshold for parr (intermediate juvenile) and adult life stages under both scenarios relative to the 1980s. Under the SSP5-8.5 scenario, these life stages could experience an increase in thermal exposure ranging from two to five times higher by the 2090s compared to the 1980s. This exposure is projected to occur during the months in which these life stages emerge, including the period when the program is active (July 20th to August 20th). Additionally, our study shows that climate change will result in a substantial rise in cumulative heat degree days, ranging from 1.9 to 5.8 times (2050s) and 2.9 to 12.9 times (2090s) in comparison to the 1980s under SSP5-8.5. Our study highlights the need for a holistic approach to reviewing the current Nechako management plan, ensuring that all species in the Nechako River system are considered especially in the face of climate change.
There is growing interest to integrate conservation initiatives into agricultural practices using a reconciliation ecology framework. In California's Central Valley, one approach to improving crucial nursery habitat for threatened and endangered fish species is by re‐creating floodplain habitats through the inundation of agricultural fields during the non‐growing season. We conducted a series of field experiments in agricultural floodplains (winter‐flooded rice fields that historically were natural floodplains) to examine whether different field preparation methods enhanced growth and survival of floodplain‐dependent fish species. Approximately 8000 juvenile fall‐run Chinook Salmon ( Oncorhynchus tshawytscha ) were reared for at least 28 days on eight, 0.2 hectares (ha) experimental fields. Each experimental field represented one of four treatments (two replicates per treatment): addition of large wood, addition of in‐field canals, addition of both large wood and in‐field canals, and control. Controls fields received no additional field preparations beyond standard post‐growing practices: that is chopping rice into stubble, baling, and removing excess rice straw, and discing the field with a single pass by plowing rice straw into the ground to promote decomposition. We found no significant difference in water temperature, fish growth or fish survival among habitat treatments. Across treatments, survival ranged from 50.1% to 78.3% and averaged 65.75% ( ⁺ /− 7.89% SE). These findings suggest agricultural floodplains require no additional modifications to promote fish growth and survival. Results illustrate the benefits of integrating working landscapes with conservation initiatives, as this approach creates more accessible and beneficial habitat for native fish species.
Land-use change is one of the main drivers of global biodiversity loss, significantly affecting ecosystems. Small water bodies, such as ponds, are particularly vulnerable to these changes; these alterations can create new ecological conditions that affect species behaviors and interactions, particularly predator–prey dynamics. By causing unequal rates of phenological shifts among interacting species, land-use change can potentially disrupt ecological interactions. This study explores the spatiotemporal dynamics of anuran larvae communities and their potential predatory insects in temporary ponds within native forest and rural areas in the subtropical montane forest of Jujuy, Argentina. We conducted weekly surveys to characterize species diversity using diversity profiles based on Hill numbers and beta diversity partitioning method. We explored and compared species phenological patterns using circular statistical analyses. Results showed a slight impoverishment of tadpole communities in the rural habitat, while the predatory insects assemblages remained relatively unchanged. Rural land use influenced the phenology of anuran larvae and predatory insects, primarily through water availability variations. Understanding predator–prey interactions in modified environments is crucial for assessing and mitigating global biodiversity crises and ecosystem transformations. This study underscores the importance of natural predators in shaping ecosystems and influencing prey dominance under changing environmental conditions.
Multiple stressors are increasingly recognized as major concerns in the sustainability of aquatic ecosystems in Africa and the myriad of ecosystem services deriving to millions of people on the continent. Stressors commonly interact to affect environmental conditions (e.g., habitat and water quality), individual species, communities, and ecological functions. Because of the complex ecological responses (that is, additive, antagonistic, and synergistic effects) they elicit, it is often challenging to develop a biomonitoring program that is effective and accurate at identifying and measuring their effects. However, with economic development in Africa, multiple stressors, such as chemical, nutrient, and organic pollution, as well as hydromorphological alterations, are growing accordingly. Thus, there is a need for evidence-based and effective natural resource management and ecosystem protection to face emerging challenges. However, despite the advancement in knowledge, progressive laws and regulations for the protection of the environment, many African countries and regions lack biomonitoring programs for assessing and monitoring ecological conditions in rivers. This chapter reviews advances made in the biomonitoring of multiple stressors in river ecosystems. Many regions of the world developed regional or national biomonitoring programs, but in Africa, most countries, except South Africa, rely on physicochemical parameters to guide water resources management and conservation. The chapter explores the range of biological communities used in bioassessment programs and the stressors against which they are best suited. The chapter further presents case studies on developing regional indices for use at the national level (e.g., Tanzanian River Scoring System, TARISS). The chapter also discusses the level of adoption of biomonitoring for the management and conservation of aquatic ecosystems in Africa and the challenges (e.g., capacity, legal and institutional frameworks) faced in developing and adopting such indices. We also discuss approaches for promoting biomonitoring and overcoming the challenges that bioindication as a tool for environmental management and conservation face. Additionally, we vouch for advancing biomonitoring in Africa to address challenges and enhance environmental management and conservation efforts. By adopting bioindication and implementing appropriate strategies, we can deepen our understanding of ecosystem health and make informed decisions for the sustainable management of aquatic ecosystems across the continent.
Photosynthetic organisms have an enormous influence on our environment through their effects on the development of other life on Earth and the way they alter the planet's geology and geochemistry. This book takes a unique approach by examining the evolutionary history of the major groups of aquatic photoautotrophs in the context of the ecophysiological characteristics that have allowed them to adapt to the challenges of life in water and thrive under past and present environmental conditions. The important role played by aquatic photoautotrophs on a planet undergoing unprecedented anthropogenic-induced change is also highlighted, in chapters on their critical function in mitigating environmental change through their physiological processes, and on the role of algae in biotechnology. This invaluable resource will be appreciated by researchers and advanced students interested in the biodiversity and evolutionary physiology of the full range of aquatic photoautotrophs, and their interaction with the environment.
Climate and land use changes can increase terrestrial runoff to aquatic systems, leading to brownification and eutrophication in northern boreal lakes. Brownification may boost bacterial respiration and production, while eutrophication can enhance primary production and algal blooms. However, their combined effects on basal producers and bacterial carbon utilization are less understood. This study explores the combined impacts of the two stressors: brownification and eutrophication on microbial dynamics in Lake Bolmen. Utilizing a field mesocosm experimental design, treatments received different combinations of organic matter (OM) and inorganic nutrients to simulate predicted future scenarios. Results showed that OM additions significantly increased bacterial production and respiration, regardless of nutrient additions. Nutrient additions enhanced bacterial production but did not affect respiration. Both nutrients and OM stimulated bacterial growth efficiency. Labile carbon from DOM was the main driver of higher bacterial respiration and short-term production increases. Fluorescence data indicated that the combination of brownification and eutrophication led to higher terrestrial DOM utilization than each stressor alone. The study suggests that future boreal lakes may become more heterotrophic, thus increasing CO2 release. These findings highlight the complex interactions between DOM and nutrients and underscore the importance of considering multiple stressors in lake management and mitigation strategies.
This study investigates the heavy metal concentrations in water and sediment samples from three stations in coastal marine wetlands in Rivers State, Nigeria: Sangama, Degema, and Tema. Samples were collected monthly from October 2021 to April 2022. Igeo, metal pollution load index (MPLI), ecological risk assessment, ecological risk factor (Er), and potential ecological risk index (PERI) were used to evaluate the impact of pollution levels. The average concentrations of heavy metals like Fe, Zn, Pb, Cd, and Cu were analyzed to assess contamination levels and ecological risks. Results show spatial variations in metal concentrations, with Sangama having the highest levels in both water and sediment. The geoaccumulation index (Igeo) and ecological risk factor (Er) were used to evaluate contamination levels and risks. Tema and Degema have generally favourable conditions with low to moderate contamination, while Sangama shows higher levels, especially for Cd, Pb, and Cu. The potential ecological risk index (PERI) and metal pollution load index (MPLI) emphasize the significant ecological risks from heavy metal pollution at all three stations. Urgent action is needed to implement effective environmental management strategies and reduce the impacts of metal pollution on aquatic ecosystems in these areas.
Groundwater plays a major, if often unrecognized, role in both hydrologic and human systems. The majority of the world's drinking water probably comes from groundwater, and in the last half century, there has been an amazing, if largely ignored, boom in agricultural groundwater use that has provided improved livelihoods and food security to billions of farmers and consumers. However, increased use of groundwater has also created problems, and there are fears — sometimes challenged — that the boom may soon turn to bust. This article reviews the recent literature on the geographic and temporal dimensions of groundwater use and the range of technological and institutional approaches that have been applied in attempts at its management. It then examines the key reasons the resource has proven so difficult to manage and concludes that, in many cases, the most promising solutions may lie outside the groundwater sector and within a broader approach to resource systems.
This chapter reviews the literature to understand the significance of making decisions about the prevention and/or control of invasive alien species (IAS) that ignore impacts on ecosystem services. It reports damage costs associated with IAS in monetary terms. The costs presented for various provisioning, regulating, and cultural services may be roughly comparable since most of the literature mostly clusters around the early 2000s. Whether damage costs of any magnitude will change the way IAS is managed will naturally depend on the benefits of the activities that lead to the introduction and spread of each species. Identifying potential damage costs and estimating their magnitude is a positive first step towards properly accounting for the full impact of IAS.
South Africa faces escalating freshwater problems and will experience prolonged water deficits within the next 25 to 30 years if current patterns of water use continue unchanged. The level of conventional water resources utilization in the country is very high and new approaches are necessary to stretch the limited water supplies available to meet projected demands for water. Significant research into new technologies and sources of supply has been carried out in South Africa and abroad during the past few decades. This has resulted in the development and evaluation of a number of innovative concepts and methodologies, as well as novel adaptations to existing approaches. These concepts and methodologies include: integration of surface water transfers into a national water grid, transfers of untapped surface water resources from countries located to the north of South Africa, exploitation of deep groundwater and the use of aquifers for storage of surplus water, atmospheric water (fog and cloud) harvesting, iceberg water utilization, desalination and direct use of sea water. Some of these options are still theoretical and unproven, while others have reached different stages of practical testing and implementation. Information on these alternatives for water supply is widely scattered over many different sources. This paper reviews the available information and examines some of these unconventional sources and options for future water supply in terms of their technical aspects, potential applications, likely impacts, approximate costs, and regional relevance in terms of alleviating predicted water shortages.
Global production of farmed fish and shellfish has more than doubled in
the past 15 years. Many people believe that such growth relieves pressure
on ocean fisheries, but the opposite is true for some types of aquaculture.
Farming carnivorous species requires large inputs of wild fish for feed. Some
aquaculture systems also reduce wild fish supplies through habitat modification,
wild seedstock collection and other ecological impacts. On balance, global
aquaculture production still adds to world fish supplies; however, if the
growing aquaculture industry is to sustain its contribution to world fish
supplies, it must reduce wild fish inputs in feed and adopt more ecologically
sound management practices.
Water is essential for life of plants, animals, humans, and human civilization. The rapidly growing human population is causing energy crisis, ozone depletion, global warming, and scarcity of cropland and this is also leading to water scarcity, water pollution, and water-related land fertility degradation. Incoming rainwater generates two types of water resources, green water and blue water. Four actions, population stabilization, seriously intended pollution abatement, water-based balancing of green and blue water requirements for social and environmental purposes, and preparedness for mega-scale food trade expansion from water-rich to water-short countries-will form the building blocks to a responsible approach to sustainability.
Fishing for recreation is a popular activity in many parts of the world and this activity has led to the development of a sector of substantial social and economic value worldwide. The maintenance of this sector depends on the ability of aquatic ecosystems to provide fishery harvest. We are currently witnessing the collapse of many commercial marine fisheries due to over-exploitation. Recreational fisheries are typically viewed as different from commercial fisheries in that they are self-sustaining and not controlled by the social and economic forces of the open market that have driven many commercial fisheries to collapse. Here we reject the view that recreational and commercial fisheries are inherently different and demonstrate several mechanisms that can lead to the collapse of recreational fisheries. Data from four high profile Canadian recreational fisheries show dramatic declines over the last several decades yet these declines have gone largely unnoticed by fishery scientists, managers, and the public. Empirical evidence demonstrates that the predatory behavior of anglers reduces angling quality to levels proportional to distance from population centers. In addition, the behavior of many fish species and the anglers who pursue them, the common management responses to depleted populations, and the ecological responses of disrupted food webs all lead to potential instability in this predator-prey interaction. To prevent widespread collapse of recreational fisheries, fishery scientists and managers must recognize the impact of these processes of collapse and incorporate them into strategies and models of sustainable harvest.
Ecological thresholds that lead to alternative community states can be exceeded through gradual perturbation or as a result of sudden disturbance. Many Great Plains streams have experienced dramatic changes in their hydrologic regime resulting from water and landuse changes that began as early as 1880. These changes, combined with the presence of many invasive species, have substantially altered the fish communities in this area. We quantified temporal changes in fish communities in 3 large river basins in relation to putative anthropogenic stressors, including increased sediment supply derived from row-crop agriculture (beginning in 1880), habitat fragmentation caused by reservoir construction (beginning in the 1950s), and reduced discharge caused by groundwater withdrawal (beginning in the 1960s). We hypothesized that these abiotic regime shifts, coupled with species invasions, would shift the system from a fish community dominated by lotic (flowing water) species to one dominated by lentic (still water) species. Further, we predicted that the timing and intensity of community change would vary across basins that experienced different types and levels of stressors. Restructuring of fish communities across the 3 river basins was driven primarily by similar increases in lentic species, with only a few declines in several large-river species. Current fish communities in these basins share <50% of the species recorded in historic collections, and these differences were driven by species extirpations and invasions. The greatest levels of community divergence over time occurred in western Kansas basins that experienced the most intense groundwater withdrawals and fragmentation by reservoirs. An alarming result from this analysis was the recent (after 1991) expansion of several invasive species in the Arkansas and lower Kansas River basins and the decline or extirpation of several native species where flow regimes are less heavily altered. Accelerating changes in the biota and habitat identified by our retrospective analysis highlight potential complications for restoring the habitat and native fish communities to a previous state.
Freshwater ecosystems are at the forefront of the global biodiversity crisis, with more declining and extinct species than in terrestrial or marine environments. Hydrologic alterations and biological invasions represent two of the greatest threats to freshwater biota, yet the importance of linkages between these drivers of environmental change remains uncertain. Here, we quantitatively test the hypothesis that impoundments facilitate the introduction and establishment of aquatic invasive species in lake ecosystems. By combining data on boating activity water body physicochemistry, and geographical distribution of five nuisance invaders in the Laurentian Great Lakes region, we show that non-indigenous species are 2.4 to 300 times more likely to occur in impoundments than in natural lakes, and that impoundments frequently support multiple invaders. Furthermore, comparisons of the contemporary and historical landscapes revealed that impoundments enhance the invasion risk of natural lakes by increasing their proximity to invaded water bodies, highlighting the role of human-altered ecosystems as "stepping-stone" habitats for the continued spread of freshwater invaders.
Artificial propagation is often seen as a way to maintain and increase or augment fish stocks that have suffered from habitat loss and overexploitation. Large-scale hatchery programs for salmonids in the Pacific Northwest have largely failed to provide the anticipated benefits; rather than benefiting the salmon populations, these programs may pose the greatest single threat to the long-term maintenance of salmonids. Fisheries scientists, by promoting hatchery technology and giving hatchery tours, have misled the public into thinking that hatcheries are necessary and can truly compensate for habitat loss. I argue that hatchery programs that attempt to add additional fish to existing healthy wild stocks are ill advised and highly dangerous.
Aquatic resource managers are continually faced with construction or site development proposals which, if allowed to proceed, would ultimately alter the physical structure and cover of fish habitat. In the absence of clear quantitative guidelines linking the change in habitat to fish, resource managers often use the change in habitat area as a basis for decisions. To assess the weight of scientific evidence in support of management decisions, we summarized both the observational and experimental freshwater fish-habitat literature. We then extracted data from experimental studies (where possible) for inclusion in a meta-analysis, to provide a more rigorous assessment of the published results of experimental habitat manipulations. We found relatively strong and consistent correlational evidence linking fish and physical habitat features, yet inconsistent evidence when narratively reviewing the experimental literature. On the whole, decreases in structural habitat complexity are detrimental to fish diversity and can change species composition. Increases in structural complexity showed increases, decreases, or no measurable changes in species and (or) communities. The majority of our meta-analyses resulted in supporting a direct link between habitat and fish abundance or biomass, with fish biomass responding most strongly to habitat change. Habitat alterations are most likely to affect individual species or community structure, and thus evaluating the extent of the effect on a biological basis depends on management objectives.
Climate change is one of a number of human forcings that affect river export of nutrients from watersheds. Past trends (1970-2000) and four future (2030 and 2050) scenarios of N, P, C and Si sources and controlling factors in watersheds globally were analyzed using the NEWS model. Hydrology is an important factor controlling river export of nutrients. Changes in river nutrient export between 2000 and 2030 due to future changes in hydrology related to climate change were compared to changes due to a scenario that integrated changes in a range of social-economic factors. These included changes in food and energy production, nutrient management practices, and GDP, among other factors. The four future scenarios were developed using the Millennium Ecosystem Assessment (MA) scenarios as a basis. The Global Orchestration scenario from the MA generally exhibited the largest human impacts on climate as well as social-economic development. At the global scale by 2030, climate change alone was projected to slightly decrease annual dissolved inorganic N export (0.2 Tg N), compared to a global increase of 3.5 Tg N using the integrated assessment approach. However, there was considerable regional variability. For example, climate accounted for much of the decrease in DIN export projected in parts of Europe and the eastern USA. In other regions such as China, climate accounted for only a small portion of the large increase in projected DIN export. Climate had a larger effect on dissolved organic N, P and C export than dissolved inorganic N and P. The effects of climate forcing on land-ocean interactions should be studied within the context of multiple human forcings.
Inland waters have received only slight consideration in recent discussions of the global fisheries crisis, even though inland fisheries provide much-needed protein, jobs, and income, especially in poor rural communities of developing countries. Systematic overfishing of fresh waters is largely unrecognized because of weak reporting and because fishery declines take place within a complex of other pressures. Moreover, the ecosystem consequences of changes to the species, size, and trophic composition of fish assemblages are poorly understood. These complexities underlie the paradox that over exploitation of a fishery may not be marked by declines in total yield, even when individual species and long-term sustainability are highly threatened. Indeed,one of the symptoms of intense fishing in inland waters is the collapse of particular stocks even as overall fish production rises-a biodiversity crisis more than a fisheries crisis.
Freshwater habitats occupy ,1% of the Earth's surface, yet are hotspots that support ,10% of all known species, and ,M of vertebrate species. Fresh waters also are hotspots for human activities that have led to widespread habitat degradation, pollution, flow regulation and water extraction, fisheries overexploitation, and alien species introductions. These impacts have caused severe declines in the range and abundance of many freshwater species, so that they are now far more imperiled than their marine or terrestrial counterparts. Here, we review progress in conservation of freshwater biodiversity, with a focus on the period since 1986, and outline key challenges for the future. Driven by rising conservation concerns, freshwater ecologists have conducted a great deal of research over the past 25 y on the status, trends, autecology, and propagation of imperiled species, threats to these species, the consequences of biodiversity loss for ecosystem functioning, metapopulation dynamics, biodiversity hotspots, reserve design, habitat restoration, communication with stakeholders, and weaknesses of protective legislation. Nevertheless, existing efforts might be insufficient to stem the ongoing and coming multitude of freshwater extinctions. We briefly discuss 4 important challenges for freshwater conservation. First, climate change will imperil both freshwater species and human uses of fresh water, driving engineering responses that will further threaten the freshwater biota. We need to anticipate both ecological and human responses to climate change, and to encourage rational and deliberate planning of engineering responses to climate change before disasters strike. Second, because freshwater extinctions are already well underway, freshwater conservationists must be prepared to act now to prevent further losses, even if our knowledge is incomplete, and engage more effectively with other stakeholders. Third, we need to bridge the gap between freshwater ecology and conservation biology. Fourth, we suggest that scientific societies and scholarly journals concerned with limnology or freshwater sciences need to improve their historically poor record in publishing important papers and influencing practice in conservation ecology. Failure to meet these challenges will lead to the extinction or impoverishment of the very subjects of our research.
The extensive development of surface and subsurface drainage systems to facilitate agricultural production throughout North America has significantly altered the hydrology of landscapes compared to historical conditions. Drainage has transformed nutrient and hydrologic dynamics, structure, function, quantity, and configuration of stream and wetland ecosystems. In many agricultural regions, more than 80% of some catchment basins may be drained by surface ditches and subsurface drain pipes (tiles). Natural channels have been straightened and deepened for surface drainage ditches with significant effects on channel morphology, instream habitats for aquatic organisms, floodplain and riparian connectivity, sediment dynamics, and nutrient cycling. The connection of formerly isolated wetland basins to extensive networks of surface drainage and the construction of main channel ditches through millions of acres of formerly low-lying marsh or wet prairie, where no defined channel may have previously existed, have resulted in large-scale conversion of aquatic habitat types, from wetland mosaics to linear systems. Reduced surface storage, increased conveyance, and increased effective drainage area have altered the dynamics of and generally increased flows in larger streams and rivers. Cumulatively, these changes in hydrology, geomorphology, nutrient cycling, and sediment dynamics have had profound implications for aquatic ecosystems and biodiversity.
Biotic homogenization is the increased similarity of biotas over time caused by the replacement of native species with nonindigenous species, usually as a result of introductions by humans. Homogenization is the outcome of three interacting processes: introductions of normative species, extirpation of native species, and habitat alterations that facilitate these two processes. A central aspect of the homogenization process is the ability of species to overcome natural biogeographic barriers either through intentional transport by humans or through colonization routes created by human activities. Habitat homogenization through reservoir construction contributes to biotic homogenization as local riverine faunas are replaced with cosmopolitan lentic species. The homogenization process has generally increased biodiversity in most freshwater faunas, as the establishment of new species has outpaced the extinction of native species. There are important exceptions, however, where the establishment of nonindigenous species has had devastating impacts on endemic species. The homogenization process appears Rely to continue, although it could be slowed through reductions in the rate of invasions and extirpations and by rehabilitating aquatic habitats so as to favor native species.
Lake Superior summer (July-September) surface water temperatures have
increased approximately 2.5°C over the interval 1979-2006,
equivalent to a rate of (11 +/- 6) × 10-2°C
yr-1, significantly in excess of regional atmospheric
warming. This discrepancy is caused by declining winter ice cover, which
is causing the onset of the positively stratified season to occur
earlier at a rate of roughly a half day per year. An earlier start of
the stratified season significantly increases the period over which the
lake warms during the summer months, leading to a stronger trend in mean
summer temperatures than would be expected from changes in summer air
temperature alone.
Freshwater invertebrate conservation faces 5 important challenges. First, ;10,000 species of freshwater invertebrates around the world may already be extinct or imperiled. Second, human pressures on freshwater resources are intense and will increase in the coming decades, putting yet more species at risk. Third, scientific knowledge about freshwater invertebrates, although substantial and useful for many groups, is far less than for the vertebrates for which much of contemporary conservation biology was designed. Even the best-known freshwater invertebrates that have achieved legal protection are perhaps 1% as well studied as the typical vertebrate. Fourth, because freshwater ecosystems are downhill from and embedded in their watersheds, freshwater conservation usually has to manage entire watersheds rather than small local sites where imperiled species occur. Fifth, society spends only modest amounts of money for freshwater invertebrate conservation. The median expenditure in Fiscal Year 2003 for freshwater invertebrate species on the US Endangered Species List was only US$24,000, and only a small minority of imperiled species is listed and receives even this modest attention. Considering these serious challenges, I believe that we need to think deliberately about the best approaches for conserving freshwater invertebrate biodiversity. The best solution may be to move away from a species-based approach that is largely derived from a terrestrial model towards broader, regional approaches that try to satisfy legitimate human needs for fresh water while preserving as much biodiversity as possible.
Anthropogenic acidification has affected biota in thousands of lakes in eastern North America and Europe. To measure the degree and extent of biological recovery following pH recovery in acidified lakes, many studies have assessed changes occurring in acid-damaged zooplankton communities. In this review we synthesize studies of zooplankton recovery from regions severely affected by acidification. In doing so, we provide a critical overview of: (1) the design of studies used to detect recovery (2) the status of communities in acidified regions and (3) our current understanding of the factors that limit recovery. The design of most studies assessing zooplankton recovery fall into three categories based on their selection of data to be used for recovery benchmarks: (1) historical (2) reference-lakes and (3) temporal. Within these study designs, the most commonly used metrics include species richness, indicator species, and relative species abundances. Many studies have used species richness as the sole indicator of recovery however, we argue that additional metrics should be considered in analyses to make conclusions more robust. Studies conducted in eastern North America and Northern Europe have demonstrated significant, though often incomplete, recovery of zooplankton communities in lakes that reach a pH> 6.0. Data collected in central Europe indicate little recovery in the heavily affected Bohemian Forest lakes, but complete recovery of species richness in the moderately acidified Tatra Mountain lakes. Factors limiting biological recovery, including slow chemical recovery, dispersal limitation, and community resistance, vary in importance among and within regions, suggesting that region- and lake-specific management approaches may be required.
Although freshwaters contribute only about .01% to Earth’s water supply, their fishes now number more than 10,000 species and thus account for at least 40% of all fish species. The continental fish faunas differ greatly in taxonomic composition and species richness, our state of knowledge of them, and the rate of discovery of unknown kinds. The ichthyofaunas of North America (about 1,050 species), Europe (about 360), and Australia-New Guinea (about 500), are the most thoroughly documented, but new species continue to be described based on discovery of previously unseen forms and species-level taxonomic splits of known species. The ichthyofaunas of tropical Asia (perhaps >3,000), Africa (perhaps >3,000 species), and South and Central America (perhaps >>5,000 species), are species rich yet incompletely known. Tropical freshwaters are the hot spots of recent and likely future ichthyological discoveries. Especially in the tropics, discoveries of species that signal new generic-level taxa are common, and new family-level groups are found occasionally. Everywhere on-going phylogenetic studies often suggest or reveal unsuspected relationships. These are times of exciting discovery and advancement of knowledge in freshwater ichthyology. New discoveries beckon us to seek the many remaining unknowns in the diversity of life on our planet. These are also times of rapid and destructive change in freshwater habitats around the globe. These threats alert us to the increasing potential for permanent loss and ignorance of much our planet’s rich aquatic biota.
Most food production depends, directly or indirectly, on freshwater resources. In the absence of importation of food commodities, population growth is constrained by the availability of local resources—including water—as well as by cultural and health-related factors. The global trade of massive amounts of food makes societies less reliant on locally available water resources, thereby allowing some populations to exceed the limits posed by their local water budget. Thus, international trade implies a virtual transfer of water resources from areas of food production to importing regions. While it is recognized that in the short term this globalization of (virtual) water resources may prevent malnourishment, famine, and conflicts, its long-term effects on the coupled human-natural system remain poorly investigated. Here we develop a minimalist modeling framework to investigate the effect of the uncontrolled trade of food products on the resilience of human societies with respect to drought and famine. Our results suggest that in the long run the globalization of water resources reduces the societal resilience with respect to water limitations in that it leaves fewer options available to cope with exceptional droughts and crop failure.
One of the major impediments to the integration of lentic ecosystems into global environmental analyses has been fragmentary data on the extent and size distribution of lakes, ponds, and impoundments. We use new data sources, enhanced spatial resolution, and new analytical approaches to provide new estimates of the global abundance of surface-water bodies. A global model based on the Pareto distribution shows that the global extent of natural lakes is twice as large as previously known (304 million lakes; 4.2 million km 2 in area) and is dominated in area by millions of water bodies smaller than 1 km2. Similar analyses of impoundments based on inventories of large, engineered dams show that impounded waters cover approximately 0.26 million km2. However, construction of low-tech farm impoundments is estimated to be between 0.1 % and 6% of farm area worldwide, dependent upon precipitation, and represents >77,000 km 2 globally, at present. Overall, about 4.6 million km2 of the earth's continental "land" surface (>3%) is covered by water. These analyses underscore the importance of explicitly considering lakes, ponds, and impoundments, especially small ones, in global analyses of rates and processes. © 2006, by the American Society of Limnology and Oceanography, Inc.
We estimated organic carbon (OC) burial over the past century in 40 impoundments in one of the most intensively agricultural regions of the world. The volume of sediment deposited per unit time varied as a function of lake and watershed size, but smaller impoundments had greater deposition and accumulation rates per unit area. Annual water storage losses varied from 0.1-20% and were negatively correlated with impoundment size. Estimated sediment OC content was greatest in lakes with low ratios of watershed to impoundment area. Sediment OC burial rates were higher than those assumed for fertile impoundments by previous studies and were much higher than those measured in natural lakes. OC burial ranged from a high of 17,000 g C m-2 a-1 to a low of 148 g C m-2 a-1 and was significantly greater in small impoundments than large ones. The OC buried in these lakes originates in both autochthonous and allochthonous production. These analyses suggest that OC sequestration in moderate to large impoundments may be double the rate assumed in previous analyses. Extrapolation suggests that they may bury 4 times as much carbon (C) as the world's oceans. The world's farm ponds alone may bury more OC than the oceans and 33% as much as the world's rivers deliver to the sea.
Freeze and breakup dates of ice on lakes and rivers provide consistent evidence of later freezing and earlier breakup around
the Northern Hemisphere from 1846 to 1995. Over these 150 years, changes in freeze dates averaged 5.8 days per 100 years later,
and changes in breakup dates averaged 6.5 days per 100 years earlier; these translate to increasing air temperatures of about
1.2°C per 100 years. Interannual variability in both freeze and breakup dates has increased since 1950. A few longer time
series reveal reduced ice cover (a warming trend) beginning as early as the 16th century, with increasing rates of change
after about 1850.
Protecting the worlds freshwater resources requires diagnosing threats over a broad range of scales, from global to local. Here we present the first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. We find that nearly 80% of the worlds population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. A similar lack of precautionary investment jeopardizes biodiversity, with habitats associated with 65% of continental discharge classified as moderately to highly threatened. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity.
Major advances in the scientific understanding and management of eutrophication have been made since the late 1960s. The control of point sources of phosphorus reduced algal blooms in many lakes. Diffuse nutrient sources from land use changes and urbanization in the catchments of lakes have proved possible to control but require many years of restoration efforts. The importance of water residence time to eutrophication has been recognized. Changes in aquatic communities contribute to eutrophication via the trophic cascade, nutrient stoichiometry, and transport of nutrients from benthic to pelagic regions. Overexploitation of piscivorous fishes appears to be a particularly common amplifier of eutrophication. Internal nutrient loading can be controlled by reducing external loading, although the full response of lakes may take decades. In the years ahead, climate warming will aggravate eutrophication in lakes receiving point sources of nutrients, as a result of increasing water residence times. Decreased silica supplies from dwindling inflows may increasingly favor the replacement of diatoms by nitrogen-fixing Cyanobacteria. Increases in transport of nitrogen by rivers to estuaries and coastal oceans have followed increased use of nitrogen in agriculture and increasing emissions to the atmosphere. Our understanding of eutrophication and its management has evolved from simple control of nutrient sources to recognition that it is often a cumulative effects problem that will require protection and restoration of many features of a lake's community and its catchment. © 2006, by the American Society of Limnology and Oceanography, Inc.
These papers presented at a symposium at Death Valley National Monument, California, November 1988, provide an appraisal of the status and conservation biology of fishes in arid lands W of the Mississippi Valley, as well as considering ethical and political questions and the progress of management and conservation efforts. The 20 chapters, organized in seven sections, cover discovery and extinction of Western fishes; ichthyological exploration of the American West, 1915-1950; impacts of Green River poisoning on management of native fishes; the Desert Fishes Council; the legacy of the Devils Hole pupfish Cyprinodon diabolis; responsibility for desert fish; ethics, federal legislation and litigation; evolution of a cooperative recovery programme in the upper Colorado River Basin; conservation genetics and genic diversity; design of reserves; history and management of preserves and refuges; conservation of Mexican freshwater fishes; hatcheries; stream renovation as management techniques; conservation and management of short-lived cyprinodontoids; transplanting short-lived fishes; management toward recovery of razorback sucker Xyrauchen texanus; life history of four endangered lacustrine suckers (Catostomidae); ecology and management of Colorado squawfish Ptychocheilus lucius; and an epilogue on the enigma of endangered species. Seventeen of the chapters are abstracted separately (see 92L/10546-10562). -J.W.Cooper
When it comes to evaluating lakes at regional and global scales, a key need is accurate estimates of the abundance and size-distribution of lakes, which are usually described with the Pareto distribution. We demonstrate the considerable uncertainty that truncation in the lower tail of the Pareto distribution introduces into lake abundance estimates and the selection of the lake size-distribution. Truncation in the lower tail eliminates lakes below a certain size and is generally performed because small lakes are not accurately represented on maps. When simulated data are truncated to mimic available lake size data, non-Pareto distributions are visually and statistically indistinguishable from the Pareto distribution. The Pareto distribution may be one of many possible forms that mimic the global lake size-distribution in the upper tail, but the fit of the Pareto to the lower tail is uncertain, largely because the abundance of small lakes is uncertain. Some other potential size-distributions, such as the lognormal distribution, predict abundances of small lakes to be orders of magnitude lower than do the Pareto distribution predictions. Highly resolved regional lake size data for the Adirondack Mountains of New York and the Northern Highland Lake District of Wisconsin do not conform to the Pareto distribution. Lake sizes on Mars also do not conform to the Pareto. Uncertainty in the lake size-distribution seriously limits understanding of the significance of lakes as repositories of organic carbon as well as the calculation of global greenhouse gas emissions from these systems.
A critical analysis of the present situation on the global water resources assessment is made. Basic data and methodological approaches used by the author for the assessment and prediction of water resources, water use and water availability on the global scale are briefly described. On the basis of data generalization of the world hydrological network new data are given on the dynamics of renewable water resources of the continents, physiographic and economic regions, selected countries as well as on the river water inflow to the world ocean. The results of the assessments for the 20th century and for the future before 2010–2025 on the water supply for municipal, industrial and agricultural needs as well as an additional evaporation from reservoirs are presented. Loads on water resources and water availability depending on socio-economic and phisiographic factors are analyzed; regions of water scarcity and water resources deficit are discovered. Possible ways of water supply improvement and elimination of water resources deficit in different regions and countries are discussed.
The fate of soil organic matter during erosion and sedimentation has been difficult to assess because of the large size and complex turnover characteristics of the soil carbon reservoir. It has been assumed that most of the carbon released during erosion is lost to oxidation. Budgets of bulk soil and soil organic carbon erosion and deposition suggest that the primary fates of eroded soil carbon across the conterminous United States are trapping in impoundments and other redeposition. The total amount of soil carbon eroded and redeposited across the United States is ∼0.04 Gt yr−1. Applying this revision to the U. S. carbon budget by Houghton et al. [1999] raises their net sequestration estimate by 20–47 %. If comparable rates of erosion and redeposition occur globally, net carbon sequestration would be ∼1 Gt yr−1.
Damage to ecosystems and threats to human health and the lack of effective mitigation require new approaches to mining regulation.
Climate warming will adversely affect Canadian water quality and water quantity. The magnitude and timing of river flows and lake levels and water renewal times will change. In many regions, wetlands will disappear and water tables will decline. Habitats for cold stenothermic organisms will be reduced in small lakes. Warmer temperatures will affect fish migrations in some regions. Climate will interact with overexploitation, dams and diversions, habitat destruction, non-native species, and pollution to destroy native freshwater fisheries. Acute water problems in the United States and other parts of the world will threaten Canadian water security. Aquatic communities will be restructured as the result of changes to competition, changing life cycles of many organisms, and the invasions of many non-native species. Decreased water renewal will increase eutrophication and enhance many biogeochemical processes. In poorly buffered lakes and streams, climate warming will exacerbate the effects of acid precipitation. Decreases in dissolved organic carbon caused by climate warming and acidification will cause increased penetration of ultraviolet radiation in freshwaters. Increasing industrial agriculture and human populations will require more sophisticated and costly water and sewage treatment. Increased research and a national water strategy offer the only hope for preventing a freshwater crisis in Canada.
