Browsing All Posts filed under »food webs«

To be continued: the legacy of the River Continuum Concept

December 14, 2021

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A recent review examined the historical importance of the River Continuum Concept (RCC), which was introduced by Robin Vannote and co-workers in 1980.  This concept revolutionised stream ecology research by prompting a shift from a descriptive to a predictive approach and encouraging multidisciplinary collaboration between biologists, geomorphologists and geochemists.  The RCC became a key framework […]

Lake management: are tipping points real?

December 14, 2021

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Freshwater biologists often seek to restore turbid shallow lakes dominated by phytoplankton to clear-water systems with a high abundance of submerged plants.  The usual plan of operation, which is often guided by lake ecosystem modelling, is to reduce external inputs of nutrients (e.g., from agricultural runoff or urban waste streams) to a threshold level at […]

How to capture the tiniest animals

December 14, 2021

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Although meiobenthic species are inconspicuous and the smallest animals living in aquatic sediments, they account for up to 80-90% of all animals in streams and lakes.  They play an important role in nutrient cycling, contribute up to half of all secondary production in freshwater food webs, and are good indicators of environmental pollution.  Meiofauna have […]

Wetlands are prime targets for herbivores

September 28, 2021

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Although studies of herbivory in freshwater ecosystems have focussed mainly on the grazing of algae, recent findings have shown that, by reducing macrophyte abundance, invertebrate herbivores can have a significant impact on the structure and function of freshwater communities.  In fact, on average they remove around 45% of the plant biomass in freshwater ecosystems, compared […]

Water abstraction changes local food chains

March 13, 2021

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The alteration of river flows by damming or extracting water is a major threat to freshwater ecosystems that can lead to habitat changes and local species extinctions.  While the impacts of dams and large-scale diversions have been the subject of many studies, the cumulative effects of small water abstractions aren’t so well understood, even though […]

Channel restoration takes time

December 16, 2020

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Channel reconfiguration is a common stream restoration technique that aims to create a stable basis for ecological functioning, but it’s expensive and its effectiveness has often been questioned.  However, channel reconfiguration assessments are typically based on the results of monitoring for up to 5-7 years post-restoration, which may be too short a period to capture […]

Ecosystem impacts of invasive carp

December 16, 2020

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The common carp (Cyprinus carpio) is one of the world’s most widespread invasive fish species and has a reputation for causing ecological damage.  It’s thought that the excretion of nutrients by dense populations of carp stimulates algal growth, which increases turbidity, and that the feeding and spawning activities of carp further increase turbidity by bringing […]

Functional feeding groups: beware of misleading assumptions

September 26, 2020

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Food webs are central to the functioning of aquatic ecosystems, and are commonly reconstructed by assigning each taxon (usually a species, genus or family) to a particular functional feeding group by reference to published information.  In the case of freshwater macroinvertebrates, the main feeding groups are: shredders, which chew on coarse organic particles; collector–filterers, which […]

A clever way to rebalance a lake

September 26, 2020

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Lakes are often subject to high-nutrient  inflows from agricultural runoff, industry and wastewater treatment, and these inputs lead to algal blooms, reduced biodiversity and a shift from clear to turbid water.  Such lakes can be remediated by reducing nutrient loads or by biomanipulation, where fish are selectively removed to lower predation pressure on zooplankton, which […]

Freshwater food webs: don’t forget parasites

September 26, 2020

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Although parasites are the dominant components in aquatic ecosystems, they are rarely considered in food web studies.  This can be a mistake, because parasites with free-living stages are taken as prey by predators, and when parasites swap hosts they carry nutrients from one host to the next.  It’s been found that adding parasites to reconstructed […]