Browsing All Posts filed under »disturbance«

How fish negotiate culverts

March 27, 2017

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While culverts are designed to facilitate the movement of water by allowing it to flow under roads or other obstructions, they can place physiological and/or behavioural restrictions on the movements of fish. Although several studies have considered the implications of culvert design for fish passage, surprisingly few have tried to identify the factors that influence […]

Tree cover makes for lower fish diversity

March 27, 2017

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A pervasive feature of lowland streams, especially in areas where land has been cleared for agriculture or urban development, is a decrease in forested cover from the headwaters to the mouth. The presence or absence of streamside tree cover has a profound influence on stream ecology. Streams running through undisturbed forests typically contain large woody […]

Factoring history into threat assessments

December 13, 2016

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Genetic variation allows populations to adapt to environmental changes, and it’s often the case that threatened species exhibit low genetic diversity. Human-produced habitat fragmentation is a well-recognised cause of genetic bottlenecks, but the additional effects of larger-scale biogeographic factors are rarely considered. As an example of such biogeographic impacts, populations that have managed to survive […]

Deciding on sites for conservation

December 13, 2016

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Biodiversity conservation is hampered by the fact that many species haven’t been described and most species ranges haven’t been mapped. As a result, in selecting sites for protection, natural resource managers often resort to the use of surrogate indicators for the species that they wish to conserve. Surrogates may be other, more common, species, or […]

How environmentally-damaging are run-of-river hydropower systems?

June 1, 2016

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Hydropower generation typically involves the creation of large dams for the storage and release of water, which can have serious adverse effects on riverine environments. However, growing pressures on governments to meet renewable energy targets have stimulated interest in small-scale hydropower systems, especially run-of-river schemes, which use the flow within a river channel and operate […]

Bioengineered riverbanks

March 23, 2016

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Streamside riparian zones support diverse and specialized plant communities and provide animal species with habitat, shelter and migratory opportunities. However, human pressures are such that measures are frequently needed to counter the problem of riverbank erosion. While bank protection has often been approached from a hard civil engineering perspective, there are ecological and aesthetic advantages […]

Do pollutants bar amphibians from stormwater ponds?

December 18, 2015

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Because of the complex array of ecologically threatening processes in urban environments, our understanding of the role that artificial ponds play in allowing aquatic populations to persist in towns and cities is quite limited. Together with green roofs, swales and stream buffers, stormwater ponds are key instruments in runoff management, but by retaining sediment as […]