Browsing All Posts filed under »lakes«

Predators concentrate on current-concentrated prey

December 13, 2016

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In marine environments, recirculating eddies, upwellings and downwellings play an important role in concentrating plankton in small areas, a process that attracts predators such as fish, mammals and birds and boosts ecological productivity significantly above background levels. However, much less is known about the ways in which physical processes may concentrate organisms and intensify food-web […]

Low biodiversity in productive lakes

December 13, 2016

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The over-supply of nutrients to lakes (through pollution, for example) stimulates the growth of plant plankton, which blocks light from reaching bottom-dwelling algae and higher plants. Therefore, nutrient excess has the potential to reduce habitat diversity and the associated biodiversity of animal plankton, macroinvertebrates and fish. An international team of biologists looked at the relationship […]

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 […]

Remote surveillance: assessing water quality

June 1, 2016

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Remote sensing technology gives natural resource managers and landowners the ability to monitor environmental conditions in new and powerful ways. However, the remote assessment of water quality in lakes and ponds is complicated by wide variations in the inorganic and organic composition of suspended particles, which affect the optical environment, and the moderate- and medium-resolution […]

Remote surveillance:monitoring fish populations

June 1, 2016

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Submerged vegetation provides freshwater animals with food, substrate and refuge opportunities. Although the structural complexity of aquatic vegetation can make it difficult for researchers to study the behaviour of resident species and measure the size of their populations, the advent of high-resolution, low-light video systems promises to alleviate these problems. Working in Florida, researchers carried […]

Surrogates for species

March 23, 2016

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Ecological communities are commonly defined and compared by reference to their species composition. However, in the case of many types of organisms, such as freshwater plankton, species-level identification is a slow, error-prone process, and for this reason there’s growing interest in characterising communities by carrying out identification at a higher taxonomic level (genus or family). […]

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 […]