Browsing All Posts filed under »predation«

Top predator boosts species richness – but not in alien ecosystems

December 13, 2016

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The spiny water flea Bythotrephes longimanus is a large cladoceran, a specialised carnivore and a top predator. Invasions of North American lakes by Bythotrephes have been linked to dramatic changes in food web structure and reductions in species diversity, which seems to contradict the expectation that top predators increase the evenness and diversity of aquatic […]

Restoration ecology: are we forgetting top-down control?

June 1, 2016

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Authors of a recent review article argue that restoration ecologists rely heavily on the assumption that natural communities are controlled by bottom-up processes (i.e., the upward transfer of nutrients and energy from plants to animals), but tend to ignore the complementary effects of top-down control by animals on nutrient cycling and the abundance and diversity […]

The dynamics of habitat choice: alien predators stifle amphibian breeding

June 1, 2016

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The way that animals select habitats reflects their need to balance the costs and benefits associated with factors such as food availability and predation risk. Therefore, habitat choices should vary in response to changes in these key factors. As an example, amphibians are expected to continually adjust the relative amounts of time that they spend […]

The dynamics of habitat choice: low-oxygen areas can be safer

June 1, 2016

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Animals should spend more time in habitats where their predation risk is low and their foraging rewards are high. However, habitat use is also affected by the degree of physiological stress imposed by environmental factors such as oxygen, pH, salinity and temperature. Because prey are under greater selective pressure from being eaten than predators are […]

Counter-productive perspectives

March 23, 2016

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A central aim of freshwater research is to understand the processes that regulate biological productivity. However, while lake-based investigations have focussed heavily on controls on primary production, river-based researchers have tended to concentrate more on production limits imposed by physical habitat requirements. If lake and river researchers think about production in different ways, and concentrate […]

Cold water plankton are bigger

March 23, 2016

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Because large-bodied zooplankton species have higher grazing rates, take a wider size-range of food items, and evade predators more easily than small species, variations in zooplankton body size can have a strong effect on aquatic food webs. An international group of biologists looked at the influence of temperature on the size of planktonic crustaceans by […]

Dietary data can be misleading

December 18, 2015

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Information on the structure and function of food webs is commonly collected by using gut content analysis to reconstruct the diets of a wide range of animal species. However, this approach can be very time consuming and expensive, and gives no information on how much ingested food is actually assimilated into the body. A supplementary […]