Browsing All Posts filed under »disturbance«

Springs – neglected ecosystems

March 26, 2022

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Springs can be defined as places on the Earth’s surface that are influenced by the exposure, and often the flow, of groundwater.  They support biodiverse ecosystems and have socioeconomic value as sources of water for drinking, agriculture, industry and recreation, , but they are often  highly vulnerable to human disturbance, such as groundwater depletion,  pollution, […]

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 […]

How riparian trees  manage their water balance

March 26, 2022

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In riverine ecosystems, riparian vegetation supports aquatic and terrestrial biodiversity, stabilises river banks and modulates water flow between the stream and the floodplain.  However, stream channelisation has led to the widespread disconnection and loss of floodplain forests.  Successful riparian restoration schemes are those that create the conditions for plants to become established and survive fluctuating […]

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 […]

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 […]

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 […]

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 […]

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 […]