Browsing All Posts filed under »food webs«

Why are there so many crocodiles in tropical waterholes?

March 26, 2018

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Transfers of organic material from one aquatic environment to another (for example, through flood pulses or animal migrations) allow productive donor ecosystems to subsidise less productive habitats. However, there are big variations in the extent to which different animal species depend on production subsidies.  To explore such differences, Australian researchers collected a wide array of […]

How sedimentation affects the food web

March 25, 2018

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In rivers and streams, high predator densities are predicted to boost algal biomass by reducing the number of grazing animals. However, in disturbed systems the smothering of stream bed surfaces by sediment is expected to have an opposite, negative effect on algal biomass.  Studies that investigate interactions between sedimentation (an abiotic stress factor) and predation […]

Size and survival in tadpoles  

December 21, 2017

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  Because interactions between predator and prey species are usually size-dependent, their ecological impacts are affected by variations in body size within predator and /or prey populations.  However, there’s been little research on the ways that such variation affects animal communities.   Using tadpoles of the brown frog (Rana pirica) as model prey and larvae of […]

Once more from the top

December 21, 2017

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Top-down trophic cascades are population-level effects transmitted along food chains, from consumers down to primary producers.  In a typical three-level food chain the loss of top predators (for example, as a result of human exploitation) allows herbivore populations to increase, which in turn reduces populations of algae or higher plants.   However, few studies have considered […]

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. […]

Mosquitofish threaten frogs

September 25, 2017

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The mosquitofish, Gambusia holbrooki, is one of the most invasive freshwater fish species in the world.  Although it’s been widely introduced for mosquito control, it has a broad diet that includes algae, higher plants, detritus, invertebrates and fish.  As a result, the species has negative predatory and competitive effects on native fish.   Although declines in […]

How cell size affects algal chemicals

September 25, 2017

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The chemical composition of microalgae – organisms such as green algae, diatoms and dinoflagellates – influences their food web interactions and the way they compete for nutrients, as well as their suitability for human exploitation in the form of biofuels, nutraceuticals and aquaculture feeds.   Because microalgae cover a wide range of cell sizes (less than […]