Browsing All Posts filed under »water flow«

Tree cover makes for lower fish diversity

March 27, 2017

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A pervasive feature of lowland streams, especially in areas where land has been cleared for agriculture or urban development, is a decrease in forested cover from the headwaters to the mouth. The presence or absence of streamside tree cover has a profound influence on stream ecology. Streams running through undisturbed forests typically contain large woody […]

How river transport affects dissolved organic matter

December 13, 2016

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In most rivers, the downstream transport of dissolved organic matter (DOM) makes large amounts of energy available to aquatic ecosystems. The River Continuum Concept (RCC) of Vannote et al. (1980) provided a useful framework for studying the influence of organic material from headwater streams on the structure and function of downstream ecosystems. The RCC hypothesized […]

Predators concentrate on current-concentrated prey

December 13, 2016

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In marine environments, recirculating eddies, upwellings and downwellings play an important role in concentrating plankton in small areas, a process that attracts predators such as fish, mammals and birds and boosts ecological productivity significantly above background levels. However, much less is known about the ways in which physical processes may concentrate organisms and intensify food-web […]

Creating fast flow refuges in streams

October 15, 2015

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Hydroelectric power plants create frequent, intense pulses in downstream river flow (hydropeaking) that are typically accompanied by increased sediment movement, high turbidity and habitat scouring. These changes can affect several aspects of the biology of fishes, including migration, spawning, early development and growth. In Switzerland, a 60% decline in catches of brown trout since 1980 […]

Modelling catchment water flows at the right scale

October 15, 2015

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Large-scale patterns of catchment water flow are most accurately represented by integrating small-scale processes across space and time. Typically, contemporary hydrological models combine remote sensing data on land cover, land use and topography with soil information, but decisions have to be made about the resolution of the data to be used in model simulations. To […]

Hotspots for riparian plants

October 15, 2015

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Streamside plants buffer the damaging effects of floodwaters and filter material and nutrients washed down from higher points in the catchment. While these processes are well understood, the effects of seepage and overland flows on riparian plants have been largely overlooked. To explore how streamside plant diversity is affected by groundwater discharge from upland areas, […]

When ponds are fertile, mussels aren’t

December 16, 2014

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Freshwater mussels help to maintain water quality by filtering suspended particles and reducing concentrations of heavy metals, pesticides and other pollutants. Unfortunately, however, freshwater mussels are experiencing dramatic declines around the world. It’s been suggested that heightened levels of suspended solids, associated with agriculture and urban development, are responsible for the decline, but the mechanism […]