Browsing All Posts filed under »disturbance«

Stream assessment by citizen scientists

July 5, 2018

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Although the potential spatial and temporal coverage of environmental data sets generated by citizen scientists is enormous, the quality of volunteer data sets depends on the use of simple, clearly defined and standardised methods.  To answer the need for an approach that can be used by citizen scientists to assess physical habitats and human pressures […]

Triggers for algal blooms: peak temperatures aren’t always important

July 5, 2018

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There are concerns that human impacts  on freshwater systems – particularly temperature increases linked to climate change and nutrient enrichment caused by run-off and pollution – are encouraging the spread of blue-green algae (cyanobacteria) capable of generating toxic blooms that threaten human and animal health.  One such case is the recent spread of Cylindrospermopsis raciborskii, […]

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 […]