This document presents the River Continuum Concept, which proposes that the structural and functional characteristics of biological communities in rivers are adapted to conform to the physical conditions and energy flow patterns of the river system. It hypothesizes that from headwaters to mouth, there is a gradient of physical conditions in rivers that elicits responses in biological populations, resulting in consistent patterns of organic matter transport and use along the river's length. Communities are proposed to form a continuum with shredder and collector-dominated assemblages in headwaters transitioning to scraper-dominated in mid-sized rivers and collectors in large rivers, reflecting shifts in food resources with stream size.
This document analyzes the relationship between flood rhythmicity and ecological patterns and processes in large tropical river systems. It finds that rivers with more rhythmic annual flooding, characterized by predictable timing and magnitude of flood peaks, tend to have higher fish species richness, more stable avian populations, and higher rates of riparian forest productivity compared to rivers with less rhythmic, unpredictable flooding. Climate change and human alterations like water extraction and dams are expected to disrupt the natural hydrologic rhythms of rivers with negative impacts on biodiversity and ecosystem function.
Effects of Beaver Dams on Stream Chemistry (2014)-mrwBryce Corbett
The document describes a study that measured various water chemistry variables upstream and downstream of two beaver dams to analyze the dams' effects. Water samples were tested for nutrients, turbidity, chlorophyll-a, dissolved oxygen, and pH. No significant differences were found between upstream and downstream levels. The study hypothesized turbidity and nutrients would be higher upstream due to sediment filtering by dams. However, small sample sizes and high variability likely affected results. Larger, longer-term studies are needed to better understand beavers' impacts on stream ecosystems.
Local human perturbations increase lakes vulnerability to climate changes: A ...Lancaster University
This document outlines a PhD proposal on assessing how local human pressures influence lakes' vulnerability and responses to climate change across Europe. The proposal involves meta-analyzing paleoecological data from 15 lakes around the Alps to compare responses of pelagic biological communities to climate change and determine if variability depends on local human pressures. The student will analyze diatom and cladoceran remains and photosynthetic pigments in sediments to compare community responses over time between lakes and quantify the influence of geomorphology and local human impacts. The supervisors are from INRA CARRTEL in France and CNR ISE in Italy.
The document summarizes research using a combination of food web and ecosystem modeling to show that impending catastrophic shifts in shallow lake ecosystems are preceded by a destabilization of the aquatic food web. Analysis of trophic interactions revealed that only a few key interactions involving zooplankton, diatoms, and detritus dictate the deterioration of food-web stability. This implies that changes in trophic organization may serve as an empirical indicator of ecosystem resilience and the risk of a regime shift.
This study examines morphological changes in threespine stickleback over eight generations following their transplantation from a large lake habitat with diverse predators to a smaller pond habitat lacking fish predators. Measurements of 20 defence and trophic traits were taken on stickleback collected from the source lake and transplant pond population between 1994 and 2009. Significant reductions were observed in several plate and spine traits, gill raker number and length, and increases in jaw length and eye diameter within eight generations - representing about one-third of the differences typically seen between natural lake and pond populations. These changes occurred rapidly and in the directions predicted based on the different predator regimes and food sources between the habitats. Both natural selection and phenotypic plasticity likely contributed to the
This document provides an overview of river science in the Indian context. It discusses key concepts in river science like scale and hierarchy, eco-geomorphology, connectivity, environmental flows, and river management approaches. It also addresses impacts of climate change on India's river systems, noting many Himalayan glaciers are retreating and extreme rainfall events are increasing in frequency and intensity. Overall, it introduces important interdisciplinary considerations for understanding and managing India's major river basins in a changing climate.
The document summarizes a PhD study investigating the impacts of invasive riparian plants on juvenile salmonids in low order streams. The study monitored 24 sites across 6 rivers, with paired control and treatment sites where invasive plant coverage exceeded 50%. Over two years, the study collected biotic and abiotic samples to assess differences between native and invaded sites, including fish surveys, invertebrate samples, and vegetation surveys. Preliminary analysis found invasive cover had no effect on overall fish biomass or diet, but positively influenced salmon density and negatively influenced trout density, possibly due to differences in habitat preferences between the two species under conditions of bank instability from plant dieback. Further analysis of samples is ongoing to better understand impacts on a fine scale
The document analyzes how wind-driven hydrodynamics influence the plankton community in a shallow coastal lake in Brazil. Canonical correspondence analysis was used to test if environmental variables like turbidity, suspended solids, and water level formed seasonal spatial gradients in response to wind. The analysis found that certain physical variables correlated with plankton distribution, though plankton responded less readily than physical factors. It indicates that wind patterns govern the spatial and temporal distribution of physical, chemical, and biological aspects in the lake.
This document analyzes the relationship between flood rhythmicity and ecological patterns and processes in large tropical river systems. It finds that rivers with more rhythmic annual flooding, characterized by predictable timing and magnitude of flood peaks, tend to have higher fish species richness, more stable avian populations, and higher rates of riparian forest productivity compared to rivers with less rhythmic, unpredictable flooding. Climate change and human alterations like water extraction and dams are expected to disrupt the natural hydrologic rhythms of rivers with negative impacts on biodiversity and ecosystem function.
Effects of Beaver Dams on Stream Chemistry (2014)-mrwBryce Corbett
The document describes a study that measured various water chemistry variables upstream and downstream of two beaver dams to analyze the dams' effects. Water samples were tested for nutrients, turbidity, chlorophyll-a, dissolved oxygen, and pH. No significant differences were found between upstream and downstream levels. The study hypothesized turbidity and nutrients would be higher upstream due to sediment filtering by dams. However, small sample sizes and high variability likely affected results. Larger, longer-term studies are needed to better understand beavers' impacts on stream ecosystems.
Local human perturbations increase lakes vulnerability to climate changes: A ...Lancaster University
This document outlines a PhD proposal on assessing how local human pressures influence lakes' vulnerability and responses to climate change across Europe. The proposal involves meta-analyzing paleoecological data from 15 lakes around the Alps to compare responses of pelagic biological communities to climate change and determine if variability depends on local human pressures. The student will analyze diatom and cladoceran remains and photosynthetic pigments in sediments to compare community responses over time between lakes and quantify the influence of geomorphology and local human impacts. The supervisors are from INRA CARRTEL in France and CNR ISE in Italy.
The document summarizes research using a combination of food web and ecosystem modeling to show that impending catastrophic shifts in shallow lake ecosystems are preceded by a destabilization of the aquatic food web. Analysis of trophic interactions revealed that only a few key interactions involving zooplankton, diatoms, and detritus dictate the deterioration of food-web stability. This implies that changes in trophic organization may serve as an empirical indicator of ecosystem resilience and the risk of a regime shift.
This study examines morphological changes in threespine stickleback over eight generations following their transplantation from a large lake habitat with diverse predators to a smaller pond habitat lacking fish predators. Measurements of 20 defence and trophic traits were taken on stickleback collected from the source lake and transplant pond population between 1994 and 2009. Significant reductions were observed in several plate and spine traits, gill raker number and length, and increases in jaw length and eye diameter within eight generations - representing about one-third of the differences typically seen between natural lake and pond populations. These changes occurred rapidly and in the directions predicted based on the different predator regimes and food sources between the habitats. Both natural selection and phenotypic plasticity likely contributed to the
This document provides an overview of river science in the Indian context. It discusses key concepts in river science like scale and hierarchy, eco-geomorphology, connectivity, environmental flows, and river management approaches. It also addresses impacts of climate change on India's river systems, noting many Himalayan glaciers are retreating and extreme rainfall events are increasing in frequency and intensity. Overall, it introduces important interdisciplinary considerations for understanding and managing India's major river basins in a changing climate.
The document summarizes a PhD study investigating the impacts of invasive riparian plants on juvenile salmonids in low order streams. The study monitored 24 sites across 6 rivers, with paired control and treatment sites where invasive plant coverage exceeded 50%. Over two years, the study collected biotic and abiotic samples to assess differences between native and invaded sites, including fish surveys, invertebrate samples, and vegetation surveys. Preliminary analysis found invasive cover had no effect on overall fish biomass or diet, but positively influenced salmon density and negatively influenced trout density, possibly due to differences in habitat preferences between the two species under conditions of bank instability from plant dieback. Further analysis of samples is ongoing to better understand impacts on a fine scale
The document analyzes how wind-driven hydrodynamics influence the plankton community in a shallow coastal lake in Brazil. Canonical correspondence analysis was used to test if environmental variables like turbidity, suspended solids, and water level formed seasonal spatial gradients in response to wind. The analysis found that certain physical variables correlated with plankton distribution, though plankton responded less readily than physical factors. It indicates that wind patterns govern the spatial and temporal distribution of physical, chemical, and biological aspects in the lake.
This study compared the movement of wild-caught guppies from Trinidadian rivers to laboratory-reared guppies in a circular flow tank. The tank was divided into zones of different water flow speeds and each fish's movement was video recorded for 5 minutes. While the total distance traveled did not differ between groups, the laboratory-reared guppies had a higher mean velocity in the faster flow zones, suggesting differences in rheotactic behavior when facing currents. This preliminary data will inform a larger study on how predation level and habitat affect guppy rheotaxis.
Jared Sartini completed a capstone project studying the effects of a remnant dam on Rum Creek in Kent County, Michigan. Field measurements were taken upstream and downstream of the dam, including bank erosion rates, substrate composition, and macroinvertebrate sampling. No significant differences were found between upstream and downstream areas. The dam is scheduled for removal to restore natural stream functions. Post-removal monitoring over 3 years is planned to evaluate the ecological response.
Restoration of a salt marsh in Boston impacted macroinvertebrate communities. Diversity and evenness indices showed differences between the restored, impacted, and dredge spoils treatments. While the restored site had lower diversity, the community composition matched natural salt marshes, indicating successful restoration. Analysis of carbon and nitrogen content found the restored site separated trophically from the other treatments. The restored site developed a specialized feeding system with potential marine inputs, showing restoration created distinct macroinvertebrate communities.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
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This document summarizes two studies evaluating the environmental impacts of Flaming Gorge Dam operations. The first study assessed the effects of overwinter double-peaking flows on trout behavior downstream, finding that trout activity increased in response to flow fluctuations. The second study examined the effects on endangered pikeminnow nursery habitat, finding that backwater characteristics are affected by flow levels and each backwater is unique annually due to sediment transport. Video recordings and topographic surveys were used to monitor fish behaviors and backwater features across varying dam operations.
This document summarizes a USDA-NIFA funded project studying fluvial geomorphology and agricultural resilience in the Deerfield River Watershed in Western Massachusetts. The project goals are to: 1) conduct fluvial geomorphic assessments; 2) implement outreach and education initiatives; 3) hold agrarian resilience roundtables; and 4) support institutional infrastructure for fluvial geomorphology. The project aims to help farms and communities manage rivers and floods following damaging events like Hurricane Irene in 2011 through scientific assessments, education resources, and stakeholder engagement.
This study examined relationships between land use, stream chemistry, and fish diversity in six headwater streams in the Little Miami River watershed. Fish and water chemistry samples were collected from each site. A total of 25 fish species were identified across sites. Stream chemistry was generally stable. Fish diversity, as measured by Simpson's Diversity Index, was positively correlated with the percentage of developed land use in the watershed and negatively correlated with the percentage of agricultural land use, though the latter was not statistically significant. Sites with more developed land use in their watersheds had greater fish diversity.
American Astronautical Society, Astronauts and Robots: Partners in Space Exploration, May 12-13, 2015 - http://astronautical.org/event/astronauts-robots
1. The document analyzes the impact of large woody debris (LWD) on populations of Chironomidae larvae, an important food source for juvenile salmonids, at Spencer Island in Everett, WA.
2. The author hypothesizes that sampling near LWD structures will yield greater numbers of Chironomidae larvae than samples taken farther from LWD, since LWD provides prime habitat.
3. Spencer Island plays an important ecological role as estuarine habitat for juvenile salmonids and waterfowl, making it a useful study site for analyzing the relationship between LWD and invertebrate communities that support fish.
The study examined the effects of stream channelization ("cleaning") on nitrogen retention in three streams in central Pennsylvania. Preliminary results showed that channelized reaches allowed nitrogen atoms to travel much further (3.7 times) compared to unaltered reference reaches. The uptake velocity, which represents overall nitrogen demand, was on average 4.7 times higher in reference reaches. These differences were likely due to a lack of stored organic matter in channelized reaches, as indicated by lower ecosystem respiration rates. The results suggest that widespread stream cleaning could reduce nitrogen uptake and potentially increase nitrogen flux into Chesapeake Bay.
Final Draft Determining the effects of freshwater releasesJonathan Valentine
This study examines the effects of freshwater releases from Lake Okeechobee on mollusk communities in the maritime environment outside the Caloosahatchee Estuary in Florida. Gastropod assemblages from dredge samples in areas at high and low risk of influence from freshwater releases were analyzed using live-dead fidelity and rank order abundance metrics. Preliminary results show a trend of increasing live-dead fidelity with greater distance from the estuary mouth, though the trend is not statistically significant. Further study is needed to better quantify potential impacts on mollusk communities from freshwater releases and address issues like urbanization and climate change on future water management practices.
This document discusses the impacts and responses to dam removals in rivers in the United States and internationally based on published studies of over 100 removals. Some key points:
- Rivers respond quickly physically to dam removals, often stabilizing within months as sediment erodes from former reservoirs and moves downstream, with channels trending back to pre-dam states.
- Fish populations have also responded rapidly, with some species recolonizing habitat upstream within days or weeks. Responses have been more mixed for less mobile bottom-dwelling species.
- Larger dam removals and those with more sediment have had greater downstream impacts than smaller removals, but removals overall have improved ecosystem function without catastrophic consequences.
This document summarizes the objectives and approach of Melanie Davis' research on developing dynamic habitat models for estuary-dependent species. The objectives are to: 1) Model changes in restoring habitat mosaics over time, 2) Determine prey availability in each habitat type, 3) Identify prey consumed by juvenile Chinook salmon, and 4) Use a bioenergetics model to estimate habitat quality as the mosaic shifts. The research involves modeling different restoration and climate change scenarios to understand their impacts on salt marsh habitats and prey availability/consumption. Field studies are being conducted to understand prey use by salmon in different habitat types to parameterize the bioenergetics model. The goal is to provide tools to help restoration planning under
This document provides a summary of Fei Xing's background and experience. It highlights over 9 years of experience in coastal hydrodynamics and sedimentology, specialized in numerical modeling of extreme events, coastal morphology, and restoration. It also lists extensive experience using modeling software like DELFT3D, SWAN, XBEACH, MIKE, and others, as well as GIS and image analysis skills.
This study assessed the baseline water quality and ecology of 7 streams near Geneva Marsh in Crawford County, Pennsylvania before construction of a proposed tire burning plant. Land use in the watersheds was analyzed using GIS and remote sensing. Water quality parameters like phosphorous and macroinvertebrate communities were assessed. Results showed urban land use decreased phosphorous and agricultural land use decreased sensitive macroinvertebrate taxa. The 3 streams with the highest agricultural and urban land use (Towpath, Shafer Run, and Williams Run) were identified for further monitoring after plant construction.
This document summarizes a student research project that studied the evolution and biogeography of stickleback fish armor traits across four watersheds on Vancouver Island, Canada. The students analyzed stickleback populations to explore how gene flow, natural selection, and population loss shape the geographic distribution of body armor morphs. They found variation in armor traits across watersheds that seems to be influenced by factors like gene flow patterns, introduced predators, and lake chemistry. Their results provide insights into how local ecological conditions and evolutionary processes interact to drive phenotypic diversity in these freshwater fish populations.
This document presents a research proposal that aims to estimate fish community diversity in the Sepetang River in Perak, Malaysia through chemometric approaches. Specifically, it will compare the forecasting capacity of fish diversity using multiple linear regression (MLR) and artificial neural networks (ANN). The research will collect data on water quality parameters and fish diversity indices at various sites along the Sepetang River. MLR and ANN models will then be developed and evaluated to determine which approach more accurately predicts fish diversity based on water quality inputs. The best performing model could provide a reliable tool for regulating and managing local fish resources.
This study evaluated the impact of pumping fresh water into Biscayne Bay near the Deering Estate to address rising salinity levels. Macroalgae and seagrass communities were monitored as indicators of ecological change. After fresh water flooding, sites separated into distinct pre- and post-flooding clusters. Relative frequencies suggested a shift toward more brackish-tolerant species and decline in marine species. Nutrient analysis found higher nitrogen levels in macroalgae like Ulva ohnoi and in seagrasses near fresh water sources, indicating flooding increased nutrient availability. Continued monitoring will compare results to previous studies to further assess flooding impacts.
1) Water extractions for irrigation can reduce stream flows in the Flint River Basin, leading to large algal mats. An experiment tested the relationship between stream discharge and algal growth.
2) The experiment found higher stream flows increased algal growth rates and biomass accumulation, likely by improving nutrient uptake.
3) While nutrient additions increased algal growth at high flows, they had little effect at low flows, indicating current velocity rather than nutrients limits algal growth under low flow conditions.
The document provides a critical appraisal of the ecosystem approach to restoring freshwater environments. It discusses the history of river degradation and the need for restoration. It then analyzes the ecosystem approach, which aims to restore heterogeneity, dynamism, and connectivity through natural geomorphic, hydrologic, and ecological processes. However, the approach has limitations due to a lack of consideration for human factors and timescales. Restoration using natural processes can take decades, which conflicts with human demands for shorter timescales. The approach is also limited in urban environments where human development constrains natural river processes. The ecosystem approach provides an ideal framework but must be adapted to real-world constraints.
This article discusses the past, present, and future of the ecohydrology of the Mississippi River system. It describes how the river system has been radically altered by human activities like navigation, flood control projects, and watershed modifications. These changes have disrupted the river's natural hydrology and hydraulics, degraded water quality, reduced biodiversity, and impacted ecosystem services. The article argues that sustainable rehabilitation of the river ecosystem requires reversing these physical, chemical, and biological alterations through projects that reestablish the historical floodplain and implement ecohydrological goals and metrics to measure success.
This study compared the movement of wild-caught guppies from Trinidadian rivers to laboratory-reared guppies in a circular flow tank. The tank was divided into zones of different water flow speeds and each fish's movement was video recorded for 5 minutes. While the total distance traveled did not differ between groups, the laboratory-reared guppies had a higher mean velocity in the faster flow zones, suggesting differences in rheotactic behavior when facing currents. This preliminary data will inform a larger study on how predation level and habitat affect guppy rheotaxis.
Jared Sartini completed a capstone project studying the effects of a remnant dam on Rum Creek in Kent County, Michigan. Field measurements were taken upstream and downstream of the dam, including bank erosion rates, substrate composition, and macroinvertebrate sampling. No significant differences were found between upstream and downstream areas. The dam is scheduled for removal to restore natural stream functions. Post-removal monitoring over 3 years is planned to evaluate the ecological response.
Restoration of a salt marsh in Boston impacted macroinvertebrate communities. Diversity and evenness indices showed differences between the restored, impacted, and dredge spoils treatments. While the restored site had lower diversity, the community composition matched natural salt marshes, indicating successful restoration. Analysis of carbon and nitrogen content found the restored site separated trophically from the other treatments. The restored site developed a specialized feeding system with potential marine inputs, showing restoration created distinct macroinvertebrate communities.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
This document summarizes two studies evaluating the environmental impacts of Flaming Gorge Dam operations. The first study assessed the effects of overwinter double-peaking flows on trout behavior downstream, finding that trout activity increased in response to flow fluctuations. The second study examined the effects on endangered pikeminnow nursery habitat, finding that backwater characteristics are affected by flow levels and each backwater is unique annually due to sediment transport. Video recordings and topographic surveys were used to monitor fish behaviors and backwater features across varying dam operations.
This document summarizes a USDA-NIFA funded project studying fluvial geomorphology and agricultural resilience in the Deerfield River Watershed in Western Massachusetts. The project goals are to: 1) conduct fluvial geomorphic assessments; 2) implement outreach and education initiatives; 3) hold agrarian resilience roundtables; and 4) support institutional infrastructure for fluvial geomorphology. The project aims to help farms and communities manage rivers and floods following damaging events like Hurricane Irene in 2011 through scientific assessments, education resources, and stakeholder engagement.
This study examined relationships between land use, stream chemistry, and fish diversity in six headwater streams in the Little Miami River watershed. Fish and water chemistry samples were collected from each site. A total of 25 fish species were identified across sites. Stream chemistry was generally stable. Fish diversity, as measured by Simpson's Diversity Index, was positively correlated with the percentage of developed land use in the watershed and negatively correlated with the percentage of agricultural land use, though the latter was not statistically significant. Sites with more developed land use in their watersheds had greater fish diversity.
American Astronautical Society, Astronauts and Robots: Partners in Space Exploration, May 12-13, 2015 - http://astronautical.org/event/astronauts-robots
1. The document analyzes the impact of large woody debris (LWD) on populations of Chironomidae larvae, an important food source for juvenile salmonids, at Spencer Island in Everett, WA.
2. The author hypothesizes that sampling near LWD structures will yield greater numbers of Chironomidae larvae than samples taken farther from LWD, since LWD provides prime habitat.
3. Spencer Island plays an important ecological role as estuarine habitat for juvenile salmonids and waterfowl, making it a useful study site for analyzing the relationship between LWD and invertebrate communities that support fish.
The study examined the effects of stream channelization ("cleaning") on nitrogen retention in three streams in central Pennsylvania. Preliminary results showed that channelized reaches allowed nitrogen atoms to travel much further (3.7 times) compared to unaltered reference reaches. The uptake velocity, which represents overall nitrogen demand, was on average 4.7 times higher in reference reaches. These differences were likely due to a lack of stored organic matter in channelized reaches, as indicated by lower ecosystem respiration rates. The results suggest that widespread stream cleaning could reduce nitrogen uptake and potentially increase nitrogen flux into Chesapeake Bay.
Final Draft Determining the effects of freshwater releasesJonathan Valentine
This study examines the effects of freshwater releases from Lake Okeechobee on mollusk communities in the maritime environment outside the Caloosahatchee Estuary in Florida. Gastropod assemblages from dredge samples in areas at high and low risk of influence from freshwater releases were analyzed using live-dead fidelity and rank order abundance metrics. Preliminary results show a trend of increasing live-dead fidelity with greater distance from the estuary mouth, though the trend is not statistically significant. Further study is needed to better quantify potential impacts on mollusk communities from freshwater releases and address issues like urbanization and climate change on future water management practices.
This document discusses the impacts and responses to dam removals in rivers in the United States and internationally based on published studies of over 100 removals. Some key points:
- Rivers respond quickly physically to dam removals, often stabilizing within months as sediment erodes from former reservoirs and moves downstream, with channels trending back to pre-dam states.
- Fish populations have also responded rapidly, with some species recolonizing habitat upstream within days or weeks. Responses have been more mixed for less mobile bottom-dwelling species.
- Larger dam removals and those with more sediment have had greater downstream impacts than smaller removals, but removals overall have improved ecosystem function without catastrophic consequences.
This document summarizes the objectives and approach of Melanie Davis' research on developing dynamic habitat models for estuary-dependent species. The objectives are to: 1) Model changes in restoring habitat mosaics over time, 2) Determine prey availability in each habitat type, 3) Identify prey consumed by juvenile Chinook salmon, and 4) Use a bioenergetics model to estimate habitat quality as the mosaic shifts. The research involves modeling different restoration and climate change scenarios to understand their impacts on salt marsh habitats and prey availability/consumption. Field studies are being conducted to understand prey use by salmon in different habitat types to parameterize the bioenergetics model. The goal is to provide tools to help restoration planning under
This document provides a summary of Fei Xing's background and experience. It highlights over 9 years of experience in coastal hydrodynamics and sedimentology, specialized in numerical modeling of extreme events, coastal morphology, and restoration. It also lists extensive experience using modeling software like DELFT3D, SWAN, XBEACH, MIKE, and others, as well as GIS and image analysis skills.
This study assessed the baseline water quality and ecology of 7 streams near Geneva Marsh in Crawford County, Pennsylvania before construction of a proposed tire burning plant. Land use in the watersheds was analyzed using GIS and remote sensing. Water quality parameters like phosphorous and macroinvertebrate communities were assessed. Results showed urban land use decreased phosphorous and agricultural land use decreased sensitive macroinvertebrate taxa. The 3 streams with the highest agricultural and urban land use (Towpath, Shafer Run, and Williams Run) were identified for further monitoring after plant construction.
This document summarizes a student research project that studied the evolution and biogeography of stickleback fish armor traits across four watersheds on Vancouver Island, Canada. The students analyzed stickleback populations to explore how gene flow, natural selection, and population loss shape the geographic distribution of body armor morphs. They found variation in armor traits across watersheds that seems to be influenced by factors like gene flow patterns, introduced predators, and lake chemistry. Their results provide insights into how local ecological conditions and evolutionary processes interact to drive phenotypic diversity in these freshwater fish populations.
This document presents a research proposal that aims to estimate fish community diversity in the Sepetang River in Perak, Malaysia through chemometric approaches. Specifically, it will compare the forecasting capacity of fish diversity using multiple linear regression (MLR) and artificial neural networks (ANN). The research will collect data on water quality parameters and fish diversity indices at various sites along the Sepetang River. MLR and ANN models will then be developed and evaluated to determine which approach more accurately predicts fish diversity based on water quality inputs. The best performing model could provide a reliable tool for regulating and managing local fish resources.
This study evaluated the impact of pumping fresh water into Biscayne Bay near the Deering Estate to address rising salinity levels. Macroalgae and seagrass communities were monitored as indicators of ecological change. After fresh water flooding, sites separated into distinct pre- and post-flooding clusters. Relative frequencies suggested a shift toward more brackish-tolerant species and decline in marine species. Nutrient analysis found higher nitrogen levels in macroalgae like Ulva ohnoi and in seagrasses near fresh water sources, indicating flooding increased nutrient availability. Continued monitoring will compare results to previous studies to further assess flooding impacts.
1) Water extractions for irrigation can reduce stream flows in the Flint River Basin, leading to large algal mats. An experiment tested the relationship between stream discharge and algal growth.
2) The experiment found higher stream flows increased algal growth rates and biomass accumulation, likely by improving nutrient uptake.
3) While nutrient additions increased algal growth at high flows, they had little effect at low flows, indicating current velocity rather than nutrients limits algal growth under low flow conditions.
The document provides a critical appraisal of the ecosystem approach to restoring freshwater environments. It discusses the history of river degradation and the need for restoration. It then analyzes the ecosystem approach, which aims to restore heterogeneity, dynamism, and connectivity through natural geomorphic, hydrologic, and ecological processes. However, the approach has limitations due to a lack of consideration for human factors and timescales. Restoration using natural processes can take decades, which conflicts with human demands for shorter timescales. The approach is also limited in urban environments where human development constrains natural river processes. The ecosystem approach provides an ideal framework but must be adapted to real-world constraints.
This article discusses the past, present, and future of the ecohydrology of the Mississippi River system. It describes how the river system has been radically altered by human activities like navigation, flood control projects, and watershed modifications. These changes have disrupted the river's natural hydrology and hydraulics, degraded water quality, reduced biodiversity, and impacted ecosystem services. The article argues that sustainable rehabilitation of the river ecosystem requires reversing these physical, chemical, and biological alterations through projects that reestablish the historical floodplain and implement ecohydrological goals and metrics to measure success.
El equipo de investigadores formado por dos físicos (Jayanth Banavarr y Amos Maritan), un botánico (Todd Cooke) y un hidrólogo (Andrea Rinaldo) sugiere que las plantas y los animales llegaron a soluciones similares (evolutivamente hablando) para resolver el problema del uso eficiente de la energía, y que evolucionaron en respuesta a los mismos principios físicos.
This document summarizes the flood pulse concept (FPC), an ecological model for river-floodplain systems. The FPC proposes that flooding periodically connects rivers to their floodplains, driving nutrient exchange and high primary production. Since the FPC was introduced in 1989, knowledge of floodplain ecology has increased, requiring updates and extensions to the original concept. The document reviews advances in understanding hydrology, biogeochemistry, biodiversity and other areas that have both supported predictions of the FPC and inspired new approaches to studying river-floodplain systems.
This document provides an analysis of coral reef systems and human impacts on them. It begins by defining coral reefs and describing the key components that make up the natural coral reef ecosystem, including the reef structure built from coral skeletons, the different types of reef formations, zonation patterns, hermatypic corals and their symbiotic relationship with zooxanthellae algae. It then discusses how human activities like pollution, overfishing and climate change are negatively impacting coral reefs by increasing stressors on the systems and reducing their resilience. The document concludes by stating that appropriate management strategies will be needed to reduce human impacts and ensure the long-term sustainability and coexistence of coral reef and human systems.
The document discusses the history and definitions of ecosystems. It notes that the term "ecosystem" was coined in 1930 but was fully defined by ecologist Arthur Tansley in 1935 as the organisms in an area interacting with the physical environment. Eugene Odum later developed the ecosystem concept and defined it as any unit with interacting organisms and physical environment leading to energy flow and material cycles. The document then discusses ecosystem components, interactions, scales, and trophic levels as well as food webs and biogeochemical cycling within ecosystems.
The document discusses the history and definitions of ecosystems. It notes that the term "ecosystem" was coined in 1930 but was fully defined by ecologist Arthur Tansley in 1935 as the organisms in an area interacting with the physical environment. Eugene Odum later developed the ecosystem concept and defined it as any unit with interacting organisms and physical environment leading to energy flow and material cycles. The document then discusses ecosystem components, interactions, scales, dynamics, and trophic levels before concluding with descriptions of biogeochemical cycling within ecosystems.
This document summarizes a study examining how selection structures species abundance distributions in an estuarine fish community. The study analyzed 30 years of monthly fish sampling data from the Bristol Channel in the UK. The key findings were:
1) Biomass was concentrated in larger bodied species in guilds occupying habitats with structure (hard-benthic and soft-benthic), which provide protection from predators. However, biomass was not concentrated in larger bodied species in open habitat guilds (pelagic and proximo-benthic) where safety in numbers is important.
2) Guilds differed in the degree to which species associate in groups, with strongly schooling species most common in pel
Ecohydraulics. Environmental Flow Assessment and river restoration. Habitat suitability models for fish and aquatic invertebrates. Studies of habitat-biota relationships at microhabitat, mesohabitat and macrohabitat (distribution) scale.
Application and adaptation of the physical habitat simulation and habitat analyses in rivers and wetlands of different regions of the globe.
Ecological modelling. Statistical techniques and machine learning are used to develop habitat suitability models for native, non-native and invasive fish species, as well as for macroinvertebrate's taxa.
Modelling relations between Flow regime and Riparian vegetation.
This document provides an overview of stream assessment and watershed functions. It defines a stream as a body of water with a current confined within banks. It discusses key components of watersheds like hydrologic cycles, stream networks, and how watersheds transport water, sediment, and dissolved materials. The document also covers stream impairments, restoration principles, and functions like transporting water and sediment and providing habitat.
A Trophic State Index for LakesAuthor(s) Robert E. Carlson.docxransayo
A Trophic State Index for Lakes
Author(s): Robert E. Carlson
Reviewed work(s):
Source: Limnology and Oceanography, Vol. 22, No. 2 (Mar., 1977), pp. 361-369
Published by: American Society of Limnology and Oceanography
Stable URL: http://www.jstor.org/stable/2834910 .
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A trophic state index for lakes'
Robert E. Carlson2
Limnological Research Center, University of Minnesota, Minneapolis 55455
Abstract
A numerical trophic state index for lakes has been developed that incorporates most
lakes in a scale of 0 to 100. Each major division (10, 20, 30, etc.) represents a doubling
in algal biomass. The index number can be calculated from any of several parameters,
including Secchi disk transparency, chlorophyll, and total phosphorus.
My purpose here is to present a new ap-
proach to the trophic classification of lakes.
This new approach was developed because
of frustration in communicating to the pub-
lic both the current nature or status of lakes
and their future condition after restoration
when the traditional trophic classification
system is used. The system presented here,
termed a trophic state index (TSI), in-
volves new methods both of defining
trophic status and of determining that status
in lakes.
All trophic classification is based on the
division of the trophic continuum, however
this is defined, into a series of classes
termed trophic states. Traditional systems
divide the continuum into three classes:
oligotrophic, mesotrophic, and eutrophic.
There is often no clear delineation of these
divisions. Determinations of trophic state
are made from examination of several di-
verse criteria, such as shape of the oxygen
curve, species composition of the bottom
fauna or of the phytoplankton, concentra-
tions of nutrients, and various measures of
biomass or production. Although each
changes from oligotrophy to eutrophy, the
changes do not occur at sharply defined
places, nor do they all occur at the same
place or at the same rate. Some lakes may
be considered oligotrophic by one criterion
and eutrophic by another; this problem is
1Contribution .
This document summarizes a study examining the relative influence of local vs. regional factors in structuring zooplankton communities across 34 interconnected ponds. Data on zooplankton communities were collected from the ponds over three years. The study found evidence of a metacommunity structure each year. Variation in zooplankton community structure was related to both local environmental factors and the spatial configuration of ponds. However, local environmental variables had a strong influence on community structure each year despite high dispersal rates between ponds. This suggests that even in highly interconnected systems, local environmental conditions can structure local communities.
Ecohydrology is an interdisciplinary field studying interactions between water and ecological systems. It considers relationships between catchments, which template water and nutrient dynamics, and habitat and biological processes. It aims to utilize these interrelationships as a basis for sustainable system management that enhances environmental capacity against human impacts. The document discusses ecohydrological principles toward sustainability, applications in China for disaster prevention, investigations of plant-water relations, and a conceptual model of a catchment system in ecohydrology. It concludes ecohydrology can provide solutions addressing water issues to accomplish sustainable urban development.
This document provides an overview of stream morphology assessment and restoration. It discusses why stream restoration is important, common causes of stream impairment, and key components of restoration projects. The document also describes stream ecosystems and processes, including watersheds, hydrology, fluvial geomorphology, sediment transport, channel patterns, dimensions, and classification. The goal is to understand stream form and function in order to properly assess conditions and plan successful restoration efforts.
1. The document outlines a planning process to develop an integrated long-term multi-site research program within the LTER Network to study interactions between pulse and press disturbances in ecosystems and their feedbacks with human societies.
2. It proposes a conceptual framework that establishes a hierarchical structure with themes of altered biogeochemical cycles, altered biotic structure, climate variability/change, and social-ecological systems.
3. Example research questions and approaches are provided for different themes that aim to better understand ecosystem structure, function, and services and their interactions with human behavior.
This document provides a summary of the professional experience and qualifications of Jeff Opperman. He has over 20 years of experience as a freshwater scientist working at the intersection of science and conservation. He currently serves as the Lead Scientist for The Nature Conservancy's Great Rivers Program, where he leads interdisciplinary teams conducting research and developing tools to support river conservation projects around the world. He has significant experience communicating science through publications and other media.
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- The REFDSS was developed for the Upper Delaware River as a user-friendly tool to enable evaluation and comparison of potential habitat availability under different flow management scenarios.
- It incorporates hydrodynamic modeling of habitat variables, hydrological modeling of reservoir release scenarios, and habitat suitability criteria for various species to calculate potential available habitat.
- The REFDSS allows modification of habitat suitability criteria and addition of new flow scenarios to compare effects on fish and mussel habitat and facilitate environmental flow management decisions.
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This study examines how beaver activity affects terrestrial ecosystems near streams. The researcher found that beaver ponds decrease the number of small trees and increase the relative abundance of red maple trees. Aquatic production from beaver ponds supports about 60% of the primary production required by terrestrial food webs. Higher trophic levels like spiders rely heavily on aquatic inputs, while lower trophic levels depend more on terrestrial production. The influence of aquatic inputs extends up to 60 meters into the forest and does not vary between pond and stream sites, likely due to the mobility of insect predators and emergent aquatic insects.
This document discusses river ecosystems and the Brahmaputra River Basin. It describes the importance of natural flow regimes and habitat heterogeneity for river health. Various habitats in the Brahmaputra River Basin are described, including fast flowing sections, pools and riffles, river confluences and meanders, the open river, and floodplain lakes. Livelihoods of local communities depend on resources from these ecosystems. An integrated ecohydrological approach is needed to assess and manage freshwater sustainability that considers the interrelationships between water and biology.
1) O documento discute ecologia de comunidades, incluindo conceitos como nicho ecológico, populações, comunidades e suas fronteiras.
2) São apresentados diversos tópicos importantes para a compreensão de comunidades ecológicas, como gradientes, sobreposição de espécies e interações entre elas.
3) Questiona-se o conceito de comunidade como unidade local interagente e sugere-se que as distribuições de espécies em uma região revelam mais sobre os processos que geram padrões de divers
Selection, drift, speciation, and dispersal are the four key processes that influence patterns of species composition and diversity in ecological communities. Selection represents fitness differences between species, drift represents stochastic changes in species abundance, speciation creates new species, and dispersal is the movement of organisms across space. While community ecology considers many specific mechanisms and interactions, all theoretical models emphasize one or more of these four fundamental processes. Organizing community ecology around these processes provides a coherent conceptual framework and clarifies similarities and differences between models.
This study examined the effects of species diversity, composition, and productivity on population- and community-level resilience in experimental aquatic food webs composed of bacteria, algae, protozoa, and rotifers. Microcosms with varying diversity levels and compositions were crossed with low and high productivity treatments. Resilience was measured by imposing a mortality perturbation and comparing recovery of perturbed communities to unperturbed controls over time. The study found that diversity enhanced community-level resilience, especially at low productivity. This effect was driven by a selection effect, with resilient communities dominated by a few species that rapidly responded. In contrast, diversity did not affect population-level resilience, which depended more on composition. Productivity had no clear effect
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
This document discusses the concept of the ecological community and argues that it should be "disintegrated" and viewed as an epiphenomenon rather than an integral unit. The key points are:
1) Local communities are not truly bounded units as the populations that comprise them are integrated over larger spatial scales.
2) Viewing communities as local assemblages hinders understanding of regional processes that generate diversity patterns.
3) Local coexistence can only be understood in the context of species' distributions across entire regions, which are determined by diversification, adaptation, and interactions over large scales.
A empresa de tecnologia anunciou um novo produto, um smartphone com câmera de alta resolução e bateria de longa duração. O aparelho também possui armazenamento expansível e processador rápido. O lançamento está programado para o próximo mês com preço inicial abaixo da média do mercado.
This document summarizes an article titled "Food Webs: Linkage, Interaction Strength and Community Infrastructure" published in The Journal of Animal Ecology in 1980. The article discusses evolving views on food web structure and examines key concepts like trophic levels, cross-linkage between species, and linkage strength. It introduces the idea of "modules" as sets of strongly interacting species that behave as functional units within food webs. The document provides definitions for various food web terminology and concepts discussed in the original article.
This document summarizes an academic paper titled "Homage to Santa Rosalia or Why Are There So Many Kinds of Animals?" by G.E. Hutchinson. The paper explores why there is such vast diversity in the number of animal species. It discusses factors like food chains, natural selection pressures that limit food chain length, effects of size changes, and the interrelations of food webs that allow for greater stability compared to independent food chains. The author aims to understand what determines the enormous number of over 1 million described animal species from an evolutionary ecology perspective.
1. The California Thrasher has a highly restricted range, occurring only in California and parts of Baja California.
2. It is found exclusively in the Upper Sonoran life zone, preferring warm, south-facing hillsides with dense chaparral vegetation.
3. Within its range, the California Thrasher shows adaptations to different levels of humidity through three subspecies that vary in coloration and geographic distribution.
The document discusses issues with defining plant associations and summarizes some key points of debate among ecologists. It notes that precise structural uniformity does not exist within associations and there is no agreement on how much variation is permitted. It also discusses how environments can be duplicated in different locations but support entirely different plant life. The document questions using either environment or vegetation as the sole means for defining associations. It concludes that variations in species composition occur both spatially within associations and temporally from year to year.
This document discusses plant succession and provides an analysis of Frederic E. Clements's book "Plant Succession: An Analysis of the Development of Vegetation". It includes:
1. An overview of Clements's book which presents his concept of the formation as a complex organism and argues that all vegetation has been developmentally related through succession.
2. A preface by Clements describing the development of his ideas on succession from previous works and extensive field work testing these concepts across North America.
3. The table of contents for Clements's book which covers topics like the causes of succession, the units of vegetation, climax communities, and succession in various world regions.
This document discusses the problem of pattern and scale in ecology over the past 20 years. Some key points:
- Major advances have helped connect ecological patterns to theory and vice versa, and recognize the importance of scale in predictions.
- Technological revolutions in computing, molecular biology, sensing, and information sharing have driven radical changes in ecology.
- Research is increasingly focusing on coupling ecological and evolutionary timescales, the influence of evolution on ecosystems, integrating organism biology and ecology through networks, and understanding spatial patterns across scales.
- Studies on rotifers, algae, Darwin's finches and guppies show evolution can impact populations and ecosystems on ecological timescales. This challenges the traditional view that
Fish presence in ponds indirectly facilitates plant reproduction across ecosystem boundaries through a trophic cascade. Fish reduce larval and adult dragonfly abundances near ponds by preying on dragonfly larvae. Fewer adult dragonflies near ponds with fish means less predation on insect pollinators. As a result, pollinators visit plants near ponds with fish more often and the plants are less pollen limited, experiencing greater reproductive success compared to plants near fish-free ponds. The study found evidence of this cross-ecosystem trophic cascade linking aquatic and terrestrial habitats.
O documento descreve uma tese de doutorado que avaliou características ecológicas e a história natural de peixes em igarapés da Amazônia Central usando a abordagem do Conceito do Rio Contínuo. Amostragens de peixes e macroinvertebrados foram realizadas em três bacias hidrográficas. Parâmetros ambientais e a distribuição de espécies e categorias tróficas foram analisados ao longo do gradiente longitudinal. Informações sobre a ecologia trófica de algumas espécies foram fornecidas
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
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Climate Impact of Software Testing at Nordic Testing DaysKari Kakkonen
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1. -
PERSPECTIVES
The River Continuum Concept’
ROBIN L. VANNOTE
Stroud Water Research Center, Academy of Natural Sciences of Pf~iladelphiu, Avorrdale, PA 19311, USA
G. WAYNE MINSHALL
Department of Biology, Idaho State University, Pocatello, ID 83209, USA
KENNETH W. CUMMINS
Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, USA
JAMES R. SEDELL
Weyerflauser Corporation, Forestry Researcft, 505 Nortfl Pearl Street, Centralia, WA 98531, USA
AND COLBERT E. GUSHING
Ecosystems Department, Battelle-Pacific Northwest Laboratories, Ricftlaild, WA 99352, USA
VANNOTE, R.L.,G. W. MINSHALL, K. W. CUMMINS, J.R. SEDELL,AND~. E. GUSHING. 1980.
The river continuum concept. Can. J. Fish. Aquat. Sci. 37: 130-137.
From headwaters to mouth, the physical variables within a river system present a con-
tinuous gradient of physical conditions. This gradient should elicit a series of responses within
the constituent populations resulting in a continuum of biotic adjustments and consistent
patterns of loading, transport, utilization, and storage of organic matter along the length of a
river. Based on the energy equilibrium theory of fluvial geomorphologists, we hypothesize that
the structural and functional characteristics of stream communities are adapted to conform
to the most probable position or mean state of the physical system. We reason that producer
and consumer communities characteristic of a given river reach become established in harinony
with the dynamic physical conditions of the channel. In natural stream systems, biological
communities can be characterized as forming a temporal continuum of synchronized species
replacements. This continuous replacement functions to distribute the utilization of energy
inputs over time. Thus, the biological system moves towards a balance between a tendency for
efficient use of energy inputs through resource partitioning (food, substrate, etc.) and an
opposing tendency for a uniform rate of energy processing throughout the year. We theorize
that biological communities developed in natural streams assume processing strategies involving
minimum energy loss. Downstream communities are fashioned to capitalize on upstream
processing inefficiencies. Both the upstream inefficiency (leakage) and the downstream adjust-
ments seem predictable. We propose that this River Continuum Concept provides a frame-
work for integrating predictable and observable biological features of lotic systems. Implica-
tions of the concept in the areas of structure, function, and stability of riverine ecosystems are
discussed.
Key words: river continuum; stream ecosystems; ecosystem structure, function; resource
partitioning; ecosystem stability; community succession; river zonation; stream geomor-
pholou
VANNOTE, R. L.,G. W. MINSHALL, K. W. CUMMINS, J. R. SEDELL, AND C. E. CUSHING. 1980.
The river continuum concept. Can. J. Fish. Aquat. Sci. 37: 130-137.
De la tCte des eaux & l’embouchure, un r&eau fluvial offre un gradient continu de condi-
tions physiques. Ce gradient devrait susciter, chez les populations habitant dans le rCseau, une
sCrie de rCponses aboutissant B un continuum d’ajustements biotiques et & des schCmas uni-
formes de charge, transport, utilisation et emmagasinage de la mat&e organique sur tout le
‘Contribution No. 1 from the NSF River Continuum Project.
Printed in Canada (J-5632)
ImprimC au Canada (55632)
i7n
2. PERSPECTIVES
parcours d’une riviere. Faisant appel a la theorie de l’equilibre Cnergetique desspecialistes de la
gtomorphologie fluviale, nous avancons l’hypothese que les caracteristiques structurales et
fonctionnelles des communautes fluviatiles sont adaptees de facon a seconformer a la position
ou condition moyenne la plus probable du systeme physique. Nous crayons que les commu-
nautes de producteurs et de consommateurs caracteristiques d’un segment donne de la riviere
semettent en harmonie avec les conditions physiques dynamiques du chenal. Dans des reseaux
fluviaux naturels, on peut dire que les communautes biologiques forment un continuum tem-
pore1 de remplacements synchronises d’especes. Grace a ce remplacement continu, il y a
repartition dans le temps de I’utilisation desapports Cnergetiques. Ainsi, le systeme biologique
vise a un Cquilibre entre une tendance vers l’utilisation efficace des apports d’energie en par-
tageant les ressources (nourriture, substrat, etc.), d’une part, et une tendance opposee vers un
taux uniforme de transformation de l’energie durant l’annee, d’autre part. A notre avis, les
communautes biologiques habitant dans des tours d’eau naturels adoptent des strategies de
transformation comportant une perte minimale d’energie. Les communautes d’aval sont
organisees de facon a tirer profit de l’inefficacite de transformation descommunautes d’amont.
On semble pouvoir p&dire a la fois l’inefficacite (fuite) d’amont et les ajustements d’aval. Nous
suggerons ce concept d’un continuum fluvial comme cadre dans lequel integrer les caracteres
biologiques previsibles et observables des systemes lotiques. Nous analysons les implications
du concept quant B la structure, fonction et stabilite des Ccosystemes fluviaux.
Received May 14, 1979 Recu le 14 mai 1979
Accepted September 19, 1979 Accept6 le 19 septembre 1979
131
Statement of the Concept
Many communities can be thought of as continua
consisting of mosaics of integrading population aggre-
~(ptes (McIntosh 1967; Mills 1969). Such a con-
coptualization is particularly appropriate to streams.
&Vera1 workers have visualized streams as possessing
assemblages of species which respond by their occur-
wnces and relative abundances to the physical gradients
prcscnt (Shelford 1911; Thompson and Hunt 1930;
sicker 1934; Ide 1935; Burton and Odum 1945; Van
&trscn 1954; Huet 1954, 1959; Slack 1955; Minshall
“1968; Ziemer 1973; Swanston et al. 1977; Platts 1979).
Expansion of this idea to include functional relation-
hips has allowed development of a framework, the
“River Continuum Concept,” describing the structure
rnd function of communities along a river system.
,; Basically, the concept proposes that understanding of
.thc biological strategies and dynamics of river systems
Equircs consideration of the gradient of physical fac-
IOrJ formed by the drainage network. Thus energy
~IQNit, and organic matter transport, stora.ge, and use
by macroinvertebrate functional feeding groups may
!. bo regulated largely by fluvial geomorphic processes.
/ fie patterns of organic matter use may be analogous
b those of physical energy expenditure proposed by
Pomorphologists (Leopold and Maddock 1953; Leo-
i Wld and Langbein 1962; Langbein and Leopold 1966;
1 Curry 1972). Further, the physical structure coupled
j
1
with the hydrologic cycle form a templet (Southwood
1977) for biological responses and result in consistent
Patterns of community structure and function and or-
@nit matter loading, transport, utilization, and stor-
‘ge along the length of a river.
Derivation of the Concept
As the cyclic theory for explaining the evolution of
land forms and streams (young, mature, ancient)
proved unsatisfactory, the concepts gradually were re-
placed by a principle of dynamic equilibrium (Curry
1972). The concept of the physical stream network
system and the distribution of watersheds as open sys-
tems in dynamic (“quasi”) equilibrium was first pro-
posed by Leopold and Maddock ( 1953) to describe
consistent patterns, or adjustments, in the relationships
of stream width, depth, velocity, and sediment load.
These “steady state” systems are only rarely character-
ized by exact equilibria and generally the river and its
channel tend toward a mean form, definable only in
terms of statistical means and extremes (Chorley
1962) ; hence, the idea of a “dynamic” equilibrium.
The equilibrium concept was later expanded to include
at least nine physical variables and was progressively
developed in terms of energy inputs, efficiency in
utilization, and rate of entropy gain (Leopold and
Langbein 1962; Leopold et al. 1964; Langbein and
Leopold 1966). In this view, equilibration of river
morphology and hydraulics is achieved by adjustments
between the tendency of the river to maximize the
efficiency of energy utilization and the opposing tend-
ency toward a uniform rate of energy use.
Based upon these geomorpholsgical considerations,
Vannote initially formulated the hypothesis that struc-
tural and functional characteristics of stream com-
munities distributed along river gradients are selected
to conform to the most probable position or mean state
of the physical system. From our collective experience
with a number of streams, we felt it was possible to
translate the energy equilibrium theory from the phys-
ical system of geomorphologists into a biological
analog. In this analysis, producer and consumer com-
munities characteristic of a given reach of the river
continuum conform to the manner in which the river
system utilizes its kinetic energy in achieving a dynamic
3. equilibrium. Therefore, over extended river reaches,
biological communities should become established
which approach equilibrium with the dynamic physical
conditions of the channel.
Implications of the Concept
It is only possible at present to trace the broa.d out-
lines of the ways the concept should apply to stream
ecosystems and to illustrate these with a few examples
for which reasonably good information is available.
From headwaters to downstream extent, the physical
variables within a stream system present a continuous
gradient of conditions including width, depth, velocity,
flow volume, temperature, and entropy gain. In de-
veloping a biological analog to the physical system,
we hypothesize that the biological organization in rivers
conforms structurally and functionally to kinetic energy
dissipation patterns of the physical system. Biotic com-
munities rapidly adjust to any changes in the redistribu-
tion of use of kinetic energy by the physcial system.
STREAMSIZEANDECOSYSTEMSTRUCTURE
ANDFUNCTION
Based on considerations of stream size, we propose
some broad characteristics of lotic communities which
can be roughly grouped into headwaters (orders l-3),
medium-sized streams (4-6), and large rivers (>6) (Fig.
1). Many headwater streams are influenced strongly by
the riparian vegetation which reduces autotrophic pro-
duction by shading and contributes large amounts of
allochthonous detritus. As stream size increases, the re-
duced importance of terrestrial organic input coincides
with enhanced significance of autochthonous primary
production and organic transport from upstream. This
transition from headwaters, dependent on terrestrial
inputs, to medium-sized rivers, relying on algal or
rooted vascular plant production, is thought to be gen-
erally reflected by a change in the ratio of gross primary
productivity to community respiration (P/R) (Fig. 2).
The zone through which the stream shifts from
heterotrophic to autotrophic is primarily dependent
upon the degree of shading (Minshall 1978). In
deciduous forests and some coniferous forests, the
transition probably is approximately at order 3 (Fig. 1) .
At higher elevations and latitudes, and in xeric regions
where riparian vegetation is restricted, the transition
to autotrophy may be in order 1. Deeply incised
streams, even with sparse riparian vegetation, may be
heterotrophic due to side slope (“canyon”) shading.
Large rivers receive quantities of fine particulate
organic matter from upstream processing of dead leaves
and woody debris. The effect of riparian vegetation is
insignificant, but primary production may often be lim-
ited by depth and turbidity. Such light attenuated sys-
tems would be characterized by P/R < 1. Streams of
lower order entering midsized or larger rivers (e.g.
the 3rd order system shown entering the 6th order
* 51 PERlPHYTedN 11
132 CAN. J. FISH. AQUAT. SCI. VOL. 37, 1980
I
COLLECTORS
PHYTOPLANKiON
9-l
U-
I2 RELATIVE CHANNEL WIDTH -
FIG. 1. A proposed relationship between stream size
the progressive shift in structural and functional attrib
of lotic communities. See text for fuller explanation.
river in Fig. 1) have localized effects of varying
tude depending upon the volume and nature
inputs..
The morphological-behavioral adaptations of
ning water invertebrates reflect shifts in types and
tions of food resources with stream size (Fig. 1).
relative dominance (as biomass) of the general
tional groups - shredders, collectors, scrapers (gr
and predators are depicted in Fig. 1. Shredders
coarse particulate organic matter (CPOM, > 1
such as leaf litter, with a significant dependence
associated microbial biomass. Collectors filter
transport, or gather from the sediments, fine and
fine particulate organic matter (FPOM, 50 pm-1
UPOM 0.5-50 pm). Like shredders, collectors
on the microbial biomass associated with the p
(primarily on the surface) and products of mi
metabolism for their nutrition. Scrapers are
primarily for shearing attached algae from
j
The proposed dominance of scrapers follows
primary production, being maximized in midsi
/
4. PERSPECTIVES 133
t.
II
0
F
a
a 0.1
a
2
{‘-Relative Diversity of Soluble Organic Compounds
-6
t:
-5 ;
Index to Biotic Diversity
>
E
4W
>
~‘2’3’4’5’6’7’8’9’~o’t~ 12
STREAM ORDER
FIG. 2. Hypothetical distribution of selected parameters through the river continuum from
headwater seeps to a twelfth order river. Parameters include heterogeneity of soluble organic
matter, maximum die1 temperature pulse, total biotic diversity within the river channel,
coarse to fine particulate organic matter ratio, and the gross photosynthesis/resp@ation ratio.
with p/R > 1. Shredders are hypothesized to be
cdominant with collectors in the headwaters, re-
flecting the importance of riparian zone CPOM and
FP()M-UPOM derived from it. With increasing Stream
b and a general reduction in detrital particle Size,
wllcctors should increase in importance and dominate
%a macroinvertebrate assemblages of large rivers
(Fig. 1).
* The predatory invertebrate component changes little
in relative dominance with stream order. Fish popula-
:jions (Fig. 1) show a shift from cool water species low
$I diversity to more diverse warm water communities
tag. Huet 1954).
jnVcrtivores.
Most headwater species are largely
Piscivorous and invertivorous species
kharacterize the midsized rivers and in large rivers
mC planktivorous species are found - reflecting the
#mi-lentic nature of such waters.
The expected diversity of soluble organic compounds
through the continuum is shown in Fig. 2 (dashed
line). Headwater streams represent the maximum inter-
&e with the landscape and therefore are predominantly
ecumulators, processors, and transporters of materials
rrom the terrestrial system. Among these inputs are
%rogeneous assembla.ges of labile and refractory dis-
mlved compounds, comprised of short- and long-chain
‘*@nits. Heterotrophic use and physical absorption of
,Jb’l’ e organic compounds is rapid, leaving the more
Fprractory and relatively high molecular weight com-
j:;,punds for export downstream. The relative importance
f
of large particle detritus to energy flow in the system
is expected to follow a curve similar to that of the
diversity of soluble organic compounds; however, its
importance may extend further downstream.
Thus the river system, from headwaters to moutg,
can be considered as a gradient of conditions frog’ a
strongly heterotrophic headwater regime to a seasoiial,
and in many cases, an annual regime of autotrophy in
midreaches, and then a gradual return to heterotrophic
processes in downstream waters (Fisher 1977). Major
bioenergetic influences along the stream continuum are
local inputs (allochthonous litter and light) and trans-
port from upstream reaches and tributaries (Fig. 1).
As a consequence of physical and biological processes,
the particle size of organic material in transport should
become progressively’smaller down the continuum (re-
flected by CPOM:FPOM ratio in Fig. 2, except for
localized input of lower order tributaries) and the
stream community response reflect progressively more
efficient processing of smaller particles.
RIVERECOSYSTEMSTABILITY
Stability of the river ecosystem may be viewed as a
tendency for reduced fluctuations in energy flow, while
community structure and function are maintained, in
the face of environmental variations. This implicitly
couples commcinity stability (sensu Ricklefs 1979) to
the instability (“noise”) of the physical system. In
5. -i
134 CAN. J. FISH. AQUAT. SCI., VOL. 37, 1980
highly stable physical systems, biotic contribution to
ecosystem stability may be less critical. However, in
widely fluctuating environments (e.g. stream reaches
with lage fluctuations in temperature), the biots may
assume critical importance in stabilizing the entire sys-
tem. In this interpretation, ecosystem stability is
achieved by a dynamic balance between forces con-
tributing to stabilization (e.g. debris dams, filter feed-
ers, and other retention devices: nutrient cycling) and
those contributing to its instability (e.g. floods, tem-
perature fluctuations, microbial epidemics). in sys-
tems with a highly stable physical structure, biotic
diversity may be low and yet total stability of the
stream ecosystem still be maintained. In contrast, sys-
tems with a high degree of physical variation may have
high species diversity or at least high complexity in
species function which acts to maintain stability.
For example, in stream zones experiencing wide die1
temperature changes, organisms may be exposed to
suboptimum temperatures for significant portions of
the day, but over some range in the die1 cycle each
organism encounters a favorable or optimum tempera-
ture range. Under these conditions an optimum tem-
perature will occur for a larger number of species than
if the thermal regime displayed minimum variance.
Also, in the thermally fluctuating system, many popu-
lations have an opportunity to process energy, and as
temperatures oscillate around a mean position, various
populations may increase or decrease their processing
rates. Thus, an important aspect of the predictably
fluctuating physical system is that it encompasses op-
timum conditions for a large number of species. This
interplay between physical and biological components
can be seen in terms of ecosystem stability by con-
sidering the response of total biotic diversity in the
river channel as balanced against the maximum die1
temperature range (AT max) (Fig. 2). Headwater
streams in proximity to groundwater supply or infiltra-
tion source areas exhibit little variation in AT max.
With increased distance from subsurface sources and
separation of the forest canopy, AT max will attain its
widest variance because of increased solar input. The
AT max amplitude is greatly diminished in high order
streams due to the buffering effect of the large volume
of water in the channel (Ross 1963). In headwater
springs and brooks, diversity may be low because bio-
logical communities are assembled from those species
which can function within a narrow temperature range
on a restricted nutritional base; the stability of the
system may be maintained by the low amplitude of
die1 and annual temperature regimes. Total community
diversity is greatest in medium-sized (3rd to 5th order
in Fig. 2) streams where temperature variations tend
to be maximized. The tendency to stabilize energy flow
in midsized streams may be aided by high biotic diver-
sity which mitigates the influence of high variance in
the physical system as characterized by AT max; i.e.
variation due to fluctuating thermal regimes should be
offset by a high diversity of biota. In large rivers,
stability of the system should be correlated with ,.
duction in variance of die1 temperature. We wisb’t
emphasize that temperature is not the only factor rr
sponsible for the change in community structure; it i
simply one of the easiest to visualize. Other factor
such as riparian influence, substrate, flow, and fq
also are important and change in predictable fas&
downstream both absolutely and in terms of the relati,,
heterogeneity of each.
TEMPORAL ADJUSTMENTS IN MAINTAINING
AN EQUILIBRIUM OF ENERGY FLOW
Natural stream ecosystems should tend towards uai
formity of energy flow on an annual basis. Althaugi
the processing rates and efficiencies of energy utilb,
tion by consumer organisms are believed to approach
equilibrium for the year, the major organic substrate,
shift seasonally. In natural stream systems, both livin,
and detrital food bases are processed continuou+,
but there is a seasonal shift in the relative importann
of autotrophic production vs. detritus loading and pra
cessing. Several studies (Minshall 1967; Coffman et rl
197 1; Kaushik and Hynes 1971; MacKay and Kalfi
1973; Cummins 1974; Sedell et al. 1974) have shown
the importance of detritus in supporting autumfi
winter food chains and providing a fine pa,rticle bag
for consumer organisms during other seasons of th
year. Autotrophic communities often form the majOt
food base, especially in spring and summer montht
(Minshall 1978).
Studies on headwater (order l-3) streams h&t
shown that biological communities in most habitat1
can be characterized as forming a temporal sequencc
of synchronized species replacement. As a species COG
pletes its growth in a particular microhabitat, it is I@
placed by other species performing essentially the sati
function, differing principally by the season of gro@
(Minshall 1968; Sweeney and Vannote 1978; VannOM
1978; Vannote and Sweeney 1979). It is this contii$*
ous species replacement that functions to distributetb
utilization of energy inputs over time (e.g. Wall!@
et al. 1977). Individuals within a species will tend tQ
exploit their environment as efficiently as possible. ‘@
results in the biological system (composite species,@’
semblage) tending to maximize energy consum$Ofi
Because some species persist through time and bec?!tg
new species become dominant, and these too are$p
ploiting their environment as efficiently as posslbla
processing of energy by the changing biological SYstem
tends to result in uniform energy processing over tim&
Thus, the biological system moves towards equilibmJn
by a trade-off between a tendency to make most C@
cient use of energy inputs through resource partiti?’
ing of food, substrate, temperature, etc. and tend$$
toward a uniform rate of energy processing thro@’
out the year. From strategies observed on small-’
$Jl
medium-sized streams (orders l-5>, we propose ,a
biological communities, developed in natural strefl
6. PERSPECTIVES 135
iedy.
namic equilibrium, assume processing strategies
~vOlvlng
minimum energy loss (termed maximum
+raling ” by Webster 1975).
ECosys~~~P~~~~~~~~~A~~~~~~~C~~~~~~~~
The dynamic equilibrium resulting from maximiza-
tion of energy utilization and minimization of variation
in its use over the year determines storage or leakage
of mru Storage includes production of new tissue
,nd physical retention of organic material for future
ptoccssing. In stream ecosystems, unused or partially
proc.essedmaterials will tend to be transported down-
,trcam. This energy loss, however, is the energy income,
Mg,,rher with local inputs, for communities in down-
,tre.,nl reaches. We postulate that downstream com-
,,,unities are structured to capitalize on these ineffi-
ciencies of upstream processing. In every reach some
nuneri;rl is processed, some stored, and some released.
me amount released in this fashion has been used in
crlcul;Lting system efficiency (Fisher 1977). Both the
upstrc;im inefficiency (leakage) and the downstream
rdjtistments seem predictable. Communities distributed
along the river are structured to process materials
(specificdetrital sizes, algae, and vascular hydrophytes)
thereby minimizing the variance in system structure
mnd function. For example, materials prone to wash-
out, such as flocculant fine-particle detritus, might be
most clliciently processed either in transport or after
deposition in downstream areas. The resistivity of fine
purticle detritus to periodic washout is increased by
tcdimcntation in depositional zones or by combination
In a matrix with the more cohesive silt and clay sedi-
ments.Thus, enhanced retention results in the forma-
IiOn of a distinct community adapted to utilize this
mcltcrial.The minimization of the variance of energy
nOW is t,he outcome of seasonal variations of energy
input rates (detritus and autotrophic production),
Nuplcd with adjustments in species diversity, spe-
:ialization for food processing, tempora1 expression of
hnctional groups, and the erosional-depositional
ransport and storage characteristics of flowing waters.
rJME INVARIANCE AND THE ABSENCE OF SUCCESSION
'NSTREAMCOMMUNITIES
A corollary to the continuum hypothesis, also arising
Iron1 the geomorphological literature (Langbein and
lcoPold 1966), is that studies of biological systems
Mablished in ,a dynamically balanced physical setting
:an be viewed in a time independent fashion. In the
““text of viewing adaptive strategies and processes
” continua along a river system, temporal change be-
‘Omes the slow process of evolutionary drift (physical
“d genetic). Incorporation of new functional com-
‘Orients into the community over evolutionary time
lecessitates an efficiency adjustment towards reduced
cakage. In natural river systems, community structure
lains and loses species in response to low probability
cataclysmic events and in response to slow processes
of channel development.
The concept of time invariance allows integration of
community structure and function along the river with-
out the illusion that successional stages are being ob-
served at a given location in a time-dependent series.
The concept of biological succession (Margalef 1960)
is of little use for river continua., because the com-
munities in each reach have a continuous heritage
rather than an isolated temporal composition within a
sequence of discrete successional stages. In fact, the
biological subsystems for each reach are in equilibrium
with the physical system at that point in the continuum.
The concept of heritage implies that in natural river
systems total absence of a population is rare, and
biological subsystems are simply shifting spatially
(visualize a series of overla.pping normal species-abun-
dance curves in which all species are present at any
point on the spatial axis but their abundance differs
from one point to the next) and not in the temporal
sense typical of plant succession.
On an evolutionary time scale, the spatial shift has
two vectors: a donwstream one involving most of the
aquatic insects and an upstream one involving molluscs
and crustaceans. The insects are believed to have
evolved terrestrially and to be secondarily aquatic. Since
the maximum terrestrial-aquatic interface occurs in the
headwaters, it is likely that the transition from land
to water first occurred here with the aquatic forms then
moving progressively downstream. The molluscs and
crayfish are thought to have developed in a marine en-
vironment and to have moved through estuaries into
rivers and thence upstream. The convergence of the
two vectors may explain why maximum species diver-
sity occurs in the midreaches.
Conclusion
We propose that the River Continuum Concept pro-
vides a framework for integrating predictable and ob-
servable biological features of flowing water systems
with the physical-geomorphic environment. The model
has been developed specifically in reference to natural,
unperturbed strea,m ecosystems as they operate in the
context of evolutionary and population time scales.
However, the concept should accommodate many un-
natural disturbances as well, particularly those which
alter the relative degree of autotrophy: heterotrophy
(e.g. nutrient enrichment, organic pohution, alteration
of riparian vegetation through grazing, clear-cutting,
etc.) or affect the quality and quantity of transport
(e.g. impoundment, high sediment load). In many
cases, these altera’tions can be thought of as reset
mechanisms which cause the overall continuum re-
sponse to be shifted toward the headwaters or seaward
depending on the type of perturbation and its location
on the river system.
A concept of dynamic equilibrium for biological
communities, despite some difficulties in absolute defini-
7. 136 CAN. J. FISH. AQUAT. XI.. VOL. 37. 1980
‘44
tion, is useful because it suggests that community struc- bLEOPOLD, L. B., AND W. B. LANGBEIN. 1962. The conceatL
ture and function adjust to changes in certain geo-
morphic, physical, and biotic variables such as stream
’ flow, channel morphology, detritus loading, size of
particulate organic material, characteristics of auto-
trophic production, and thermal responses. In develop-
ing a theory of biological strategies along the river
continuum, it also should be possible to observe a
number of patterns that describe various processing
rates, growth strategies, metabolic strategies, and com-
munity structures and functions. Collection of ex-
tensive data sets over the long profile of rivers are
needed to further test and refine these ideas,
Acknowledgments
The ideas presented here have been refined through dis-
cussions with our associates in the River Continuum Project,
especially T. L. Bott, J. D. Hall, R. C. Petersen, and F. J.
Swanson; and other colleagues including S. A. Fisher, C. A.
S. Hall, L. B. Leopold, F. J. Triska, and J. B. Webster. We
are grateful to J. T. Brock, A. B. Hale, C. P. Hawkins,
J. L. Meyers, and J. R. Moeller for their constructive
criticism of a draft version of the manuscript. This work
was supported by the U.S. National Science Foundation,
Ecosystems Studies program under grant numbers BMS-
75-07333 and DEB-7811671.
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