Browsing All Posts filed under »water quality«

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 […]

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 […]

A lesson from fish: don’t let stress ruin procreation

March 26, 2022

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Annual fishes live in temporary ponds that dry out completely in summer.  As a result they have the shortest life spans of all vertebrates: after a few months they perish and the next generation depends on the survival of their drought-proof eggs, which hatch when the pond is eventually flooded.  As the shallow ponds dry […]

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 […]

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 […]

Restoration of urban headwaters pays dividends

September 28, 2021

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Because urban streams are often ecologically degraded as a result of channelisation and pollution, restoration work is often attempted to improve ecosystem structure and function.  This usually involves remodelling of the stream channel.  Knowing that there are predictable shifts in ecosystem processes between headwater streams and the main body of the river, American ecologists investigated […]

Key wetland species deliver most ecosystem services

September 28, 2021

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There’s a lot of evidence that in ecosystems such as grasslands and forests, biodiversity is positively related to productivity and to the efficiency of nutrient recycling and decomposition.   On this basis it can be argued that the loss of biodiversity is likely to damage the delivery of ecosystem services.  However, in the case of wetlands, […]

Earthquakes and groundwater

September 28, 2021

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Studies have shown that earthquake activity can change the chemistry of nearby groundwater reserves – for example, strong increases in chlorides and sulphates in groundwater were recorded in the period before and after the Kobe earthquake of 1995.  Such changes can alter the communities of organisms living in the aquifer and lead to the extinction […]

Assessing human impacts on river systems

September 28, 2021

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Because many river systems have been significantly modified as a result of human activities, indicators of changing river structure and function are very helpful in guiding our efforts to manage rivers on a sustainable basis.  A number of different indicators based on the hydrology, chemistry or biology of rivers have been developed, but in many […]