Browsing All Posts filed under »nutrients«

When drought eliminates fish…

March 30, 2019

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  Droughts can lead to lasting changes in the condition of wetlands.  For example, as drying occurs water levels drop and light penetration improves, which allows aquatic plants in the seed bank to germinate.  By stabilizing sediments, outcompeting algal plankton and  providing refuge to zooplankton grazers, newly established stands of aquatic plants can cause originally […]

How fire affects stream communities

March 30, 2019

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  By removing riparian vegetation, wildfires can have significant effects on river ecology, especially in headwater systems where fringing plant life helps to regulate stream temperature and provides a source of carbon in the form of leaf litter and woody debris.  To help understand the impacts of fire on streams, and the length of time […]

How the food web affects river restoration

October 8, 2018

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River restoration commonly  concentrates on improving habitat quality for threatened fish populations.  However, because stream fish are strongly influenced by food availability, competition and predation, a case can be made for also incorporating food web modelling into the restoration process.  A group of environmental scientists developed an ecosystem model and applied it to a river-floodplain […]

Lakes are good for river species

October 8, 2018

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While it’s known that terrestrial landscape features, such as soil type, topography and land use, influence the abundance and distribution of stream fish, only a few studies have considered the possible effects of lakes on stream fish populations.  Biologists carried out a three-year study on native brook trout (Salvelinus fontinalis) in 36 streams in the […]

Worms, midges and the greenhouse effect

July 5, 2018

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Severely impacted aquatic environments such as urban wetlands and wastewater treatment ponds are designed to treat large amounts of carbon and nitrogen, which raises concerns about their potential greenhouse gas emissions.  Because pollution-tolerant worms (oligochaetes) and insects (midges) can reach very high densities in such systems, it’s possible that their activities influence  the flux of […]

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 […]