Browsing All Posts filed under »plants«

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 […]

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 […]

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 […]

Aquatic plants help animal plankton to disperse

March 25, 2018

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Freshwater bodies containing aquatic plants generally support a wide range of animal plankton. If the dormant stages of zooplankton are attached to roots and the submerged parts of plants, the dislodgement and displacement of aquatic vegetation during floods could play a role in plankton dispersal. To assess this possibility, Argentinian researchers collected specimens of free-floating […]

Riparian roots help streams breathe

December 21, 2017

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In aquatic systems, especially those with abundant plants, dissolved oxygen concentrations often show strong daily fluctuations because there’s a net input of oxygen from photosynthesis during the day but a net loss of oxygen due to   respiration at night.  When researchers working on a small tropical stream in São Paulo State, Brazil recorded this pattern […]

Collapsing waterweeds:  shading and herbivory work together

December 21, 2017

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In lakes and ponds, aquatic plants help to maintain clear-water conditions and their decline can cause a shift to a turbid state with lower biodiversity.  But what triggers the collapse of waterweed populations?  Grazing by aquatic herbivores would seem to be an obvious cause, but supporting evidence for this idea has proved surprisingly elusive, leading […]

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 […]