Browsing All Posts filed under »disturbance«

Why are there so many crocodiles in tropical waterholes?

March 26, 2018

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Transfers of organic material from one aquatic environment to another (for example, through flood pulses or animal migrations) allow productive donor ecosystems to subsidise less productive habitats. However, there are big variations in the extent to which different animal species depend on production subsidies.  To explore such differences, Australian researchers collected a wide array of […]

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 […]

Paying to restore urban streams

March 25, 2018

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Rivers and streams provide many ecosystem services, including the supply and purification of water, climate regulation, flood protection, fisheries, aesthetic values and recreation.  In urban settings, the loss of stream ecosystem services as a result of pollution, erosion and habitat degradation has prompted widespread attempts at environmental repair. However, although levels of investment in urban […]

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 […]

Aquatic plants help animal plankton to disperse

March 25, 2018

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Freshwater bodies containing aquatic plants generally support a wide range of animal plankton. If the dormant stages of zooplankton are attached to roots and the submerged parts of plants, the dislodgement and displacement of aquatic vegetation during floods could play a role in plankton dispersal. To assess this possibility, Argentinian researchers collected specimens of free-floating […]

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 […]

Invasive waterplants: be prepared

December 21, 2017

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Investigators from Europe, the USA and New Zealand recently authored a comprehensive review of methods for the management of invasive freshwater plants.   As well as describing options for mechanical, biological and chemical control, the review includes information on relevant biology, management costs, the effects of management on freshwater ecosystems, and the post-management restoration of native […]