Browsing All Posts filed under »nutrients«

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 […]

Helping to resolve the plankton paradox

March 26, 2018

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The richness of plant plankton communities in natural ponds and small lakes is very high – typically up to about 80 species at any one time in most systems. However, ecological theory predicts that the number of coexisting species should be no greater than the number of limiting resources, and normally in the case of […]

Riparian roots help streams breathe

December 21, 2017

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In aquatic systems, especially those with abundant plants, dissolved oxygen concentrations often show strong daily fluctuations because there’s a net input of oxygen from photosynthesis during the day but a net loss of oxygen due to   respiration at night.  When researchers working on a small tropical stream in São Paulo State, Brazil recorded this pattern […]

Deforestation means defishation

December 21, 2017

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The impacts of tropical deforestation on terrestrial biodiversity are well known but only a few studies have considered the impacts of deforestation on freshwater systems.  Such effects are likely to be significant, given the importance of riparian vegetation as a source of nutrients and the high abundances of fish in tropical floodplain forests.  In a […]

More clarity on climate change

December 21, 2017

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Although climate change is warming many lakes around the world, there are big variations in their rate of temperature increase.  This variability is thought to be partly due to the fact that lakes differ widely in terms of water clarity, which is affected by factors such as land management, rainfall and changes in dissolved organic […]