Browsing All Posts filed under »habitat diversity«

Freshwater fish surveys: direct observation works well

March 26, 2018

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Although surveys of freshwater fish populations often rely on electrofishing, it’s difficult to use this technique in some habitats. An alternative sampling method is direct observation by snorkelling, an approach often applied in marine environments.  While comparisons of the sampling efficiency of electrofishing and snorkelling have been carried out, most of them have been based […]

Freshwater conservation needs flagship umbrellas

March 26, 2018

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Flagship species are surrogate species that are used to raise public awareness and funds for conservation, while umbrella species are those which ensure that a wide range of co-occurring species are conserved when they themselves are afforded protection.  In principle, conservation efforts should be enhanced by identifying species – dubbed “flagship umbrellas” – that combine […]

Guppies know their way around

March 25, 2018

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Rats, mice and other rodents can quickly learn to solve complex spatial problems such as mazes consisting of sequences of left-right turns. Although the spatial abilities of rodents may be the result of their burrow-dwelling existence, it’s also possible that such abilities are widely shared by other vertebrates. Fish are known to have well-developed spatial […]

Benefits and costs of habitat complexity

December 21, 2017

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The fact that biodiversity tends to be higher in structurally complex habitats suggests that, on balance, the fitness-related advantages of habitat complexity outweigh the disadvantages.  Possible advantages include a greater supply of locations where animals can hide from predators and conserve their energy, and higher abundances of potential prey.  Also, in complex habitats less energy […]

Restoration and invertebrates: Build it and at least some of them will come

September 25, 2017

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It’s commonly assumed that the biodiversity of a disturbed ecosystem can be improved by restoring its original physical and chemical conditions. According to this “Field of Dreams” view (“build it and they will come”), ecosystem recovery occurs through the recolonization activities of lost species.  While a lot of river restoration is founded on Field of […]

Restoration and invertebrates: Reappraising stream condition indicators

September 25, 2017

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In degraded rivers and stream systems, the replanting of riparian vegetation is a common restoration activity, partly because increases in shading, nutrient interception and litter fall are expected to provide food and habitat benefits for aquatic communities. Changed habitat conditions should be reflected in indices of stream condition, such as those based on macroinvertebrate richness. […]

Lateral thinking on riverbank erosion

September 25, 2017

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Although bank erosion is often thought of as problem that has to be addressed through engineered stabilization, the lateral migration of meandering streams is a natural mechanism that redistributes channel sediment and maintains habitat diversity. New riparian zones are formed as sediment is deposited on the inside of bends and colonised by vegetation.  Meandering creates […]