Browsing All Posts filed under »connectivity«

Freshwater megafauna under threat

March 26, 2022

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Because large-bodied animal species tend to have a higher than average extinction risk, there are concerns that freshwater megafauna (species with body weights over 30 kg) are relatively vulnerable to human-induced disturbances such as reduced river flows, habitat fragmentation and pollution.  In the 40 years leading up to 2012, global populations of freshwater megafauna declined […]

Dams challenge platypus populations

March 26, 2022

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The construction of dams has many adverse effects on river hydrology and ecology.  Dams limit animal movements and reduce the cover of riparian vegetation, which leads to bank erosion and the filling of stream pools with sediment.  Dam-related impacts have been documented for many types of riverine animals, including macroinvertebrates, amphibians and waterbirds.  However, the […]

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 […]

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 […]

Gene flow in complex river systems

December 14, 2021

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Understanding how variations in habitat connectivity affect gene flow and possible genetic isolation in river systems is tricky because of the unique structural features of stream ecosystems, which are notoriously difficult to model: unlike terrestrial landscapes, they are linear branching networks, which means that overland distance is often a poor indicator of the correlation between […]

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 […]

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 […]

Assessing river condition from the air

June 7, 2021

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Although attempts are commonly made to restore streams impacted by disturbance, follow-up monitoring to assess a project’s success is often minimal due to budget limitations.   However, new approaches involving the use of small unmanned aerial vehicles (drones) offer the possibilities for remote stream assessment, with potentially great gains in terms of cost-effectiveness and reduced field […]

How rivers regulate fish numbers

June 7, 2021

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Recruitment processes, which determine the number of young animals entering a  population each year, are central considerations in our attempts to understand fluctuations in abundance.  Although recruitment has been a key focus of fisheries scientists for many years, most of their work has involved marine fish species, and there’s been no fully integrated and comprehensive […]

Aquatic ecosystem services: rethinking streamside planting

March 13, 2021

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Spatial patterns in the loss of natural land cover to agriculture have a significant effect on ecosystem services, including those provided by landscape features that interrupt runoff flows to rivers.  For example, the number, size and location of woodland patches all have an impact on ecosystem services such as sediment trapping, pollutant retention and the […]