Browsing All Posts filed under »sediment«

How sedimentation affects the food web

March 25, 2018

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In rivers and streams, high predator densities are predicted to boost algal biomass by reducing the number of grazing animals. However, in disturbed systems the smothering of stream bed surfaces by sediment is expected to have an opposite, negative effect on algal biomass.  Studies that investigate interactions between sedimentation (an abiotic stress factor) and predation […]

Serious streambank erosion in farming catchments

March 25, 2018

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Streambank erosion is influenced by a number of factors, including water movement, freeze-thaw cycles, bank drying, vegetative cover, animal trampling and agricultural practices. Studies show that bank erosion can be  responsible for a significant fraction of the sediment exported by streams and rivers.  In western Europe, where many areas of grassland have been converted to […]

Simplifying urban stream assessment

December 21, 2017

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Urban streams experience high levels of stormwater runoff and channel erosion, and represent a significant challenge for ecological restoration.  Nevertheless, it’s generally agreed that urban stream restoration should aim to mimic the natural (pre-development) flow regime as closely as possible.  It’s been proposed that ecologically important aspects of flow can be used as a basis […]

Ironing out harmful algal blooms

September 25, 2017

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An understanding of how iron affects the supply of nutrients in aquatic systems may open the door to better success in managing harmful algal blooms. In highly productive lakes, the release of phosphorus stored in the bottom sediment can encourage bloom development, but nutrient release is retarded in the presence of iron, which precipitates phosphorus […]

Lateral thinking on riverbank erosion

September 25, 2017

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Although bank erosion is often thought of as problem that has to be addressed through engineered stabilization, the lateral migration of meandering streams is a natural mechanism that redistributes channel sediment and maintains habitat diversity. New riparian zones are formed as sediment is deposited on the inside of bends and colonised by vegetation.  Meandering creates […]

Coarse, shallow and wooden… but useful nonetheless

June 19, 2017

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Coarse woody debris (CWD) derived from shoreline trees provides an important, spatially complex habitat and a food source for lake-dwelling organisms. Here are some interesting facts about lake CWD, taken from a recent review paper: In the absence of the physical action of flowing water, CWD breaks down more slowly in lakes than in streams. […]

A disturbing mix

June 19, 2017

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The common carp (Cyprinus carpio) has been introduced to many locations around the world and is highly invasive.  Its habit of foraging by digging in the bottom substrate significantly alters freshwater systems by uprooting plants, resuspending sediment, and increasing turbidity and the release of nutrients.  However, the extent to which aquatic nutrient flows are affected […]