Browsing All Posts filed under »nutrients«

Aquatic plants regulate downstream nutrients

March 26, 2022

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Just as the processes of respiration and nutrient uptake by living cells affect the chemistry of the human body, the activities of all life-forms in a body of water influence its metabolism and carbon dynamics.  In freshwater streams, aquatic plants and algae are important agents of metabolism because they act as the stream’s internal source […]

The net effect: caddis flies and streambed flow

March 26, 2022

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The beds of streams are dynamic interfaces where water, nutrients and living organisms move between surface and sub-surface environments, and streambed permeability has a significant influence on processes such as nitrogen cycling and organic matter decomposition.  Although the physics of streambed exchange are well understood, interactions between physical and biological processes have received relatively little […]

Lake management gets harder as the climate changes

March 26, 2022

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Excessive inflows of nutrients, especially phosphorus in fertilisers, pesticides and sewage, reduce water quality in lakes and reservoirs and can encourage toxic algal blooms, often with serious implications for public health, food security and biodiversity.  Increases in nutrient inputs are partly due to increased rainfall associated with  climate change.  And the availability and residence times […]

To be continued: the legacy of the River Continuum Concept

December 14, 2021

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A recent review examined the historical importance of the River Continuum Concept (RCC), which was introduced by Robin Vannote and co-workers in 1980.  This concept revolutionised stream ecology research by prompting a shift from a descriptive to a predictive approach and encouraging multidisciplinary collaboration between biologists, geomorphologists and geochemists.  The RCC became a key framework […]

Lake management: are tipping points real?

December 14, 2021

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Freshwater biologists often seek to restore turbid shallow lakes dominated by phytoplankton to clear-water systems with a high abundance of submerged plants.  The usual plan of operation, which is often guided by lake ecosystem modelling, is to reduce external inputs of nutrients (e.g., from agricultural runoff or urban waste streams) to a threshold level at […]

Water flow through the beds of streams

December 14, 2021

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The permeability of saturated sediments at the bottom of streams, where surface water and groundwater can mix, has a strong influence on the exchange of mass and energy across the sediment-water interface.  Streambed permeability depends mainly on sediment properties such as pore networks and the size and sorting of particles, and can vary greatly, even […]

Trends in the relative size of lake catchments

December 14, 2021

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The influence of catchment-derived inputs of materials and energy on lake dynamics is commonly represented by the drainage ratio, which is the ratio of catchment area to lake area.  Surprisingly however, there’s a lack of information about catchment size – lake size relationships in general, and whether they vary with geographic region or lake type, […]

Guidelines for conserving groundwater ecosystems

December 14, 2021

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Aquatic groundwater-dependent ecosystems include subsurface aquifers, springs, seepage wetlands and other groundwater-fed surface waters.  Their biodiversity is high: for example, in Europe around 13% of all freshwater animal species are found only in groundwater.  Many of these species are rare, with limited distributions, and some are “living fossils”.  Groundwater species deliver ecosystem services by recycling […]

How to capture the tiniest animals

December 14, 2021

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Although meiobenthic species are inconspicuous and the smallest animals living in aquatic sediments, they account for up to 80-90% of all animals in streams and lakes.  They play an important role in nutrient cycling, contribute up to half of all secondary production in freshwater food webs, and are good indicators of environmental pollution.  Meiofauna have […]

Land use patterns can aggravate toxic plankton blooms

September 28, 2021

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An understanding of how environmental factors affect the composition of biological communities is a crucial prerequisite for managing challenges due to climate change, land use practices and invasive species.  However, establishing the significance of interacting local and regional factors that vary widely across space and time is a challenge in itself.   Canadian biologists set out […]