Browsing All Posts filed under »lakes«

When drought eliminates fish…

March 30, 2019

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  Droughts can lead to lasting changes in the condition of wetlands.  For example, as drying occurs water levels drop and light penetration improves, which allows aquatic plants in the seed bank to germinate.  By stabilizing sediments, outcompeting algal plankton and  providing refuge to zooplankton grazers, newly established stands of aquatic plants can cause originally […]

Getting the message across

October 8, 2018

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Since recreational boaters can unintentionally spread invasive aquatic species while transporting boats and equipment from one body of water to another, it’s important that management agencies communicate the need for boaters to clean, drain and dry their gear after use.  Researchers used a questionnaire-based approach to find out if the way the “clean, drain and […]

Lakes are good for river species

October 8, 2018

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While it’s known that terrestrial landscape features, such as soil type, topography and land use, influence the abundance and distribution of stream fish, only a few studies have considered the possible effects of lakes on stream fish populations.  Biologists carried out a three-year study on native brook trout (Salvelinus fontinalis) in 36 streams in the […]

Triggers for algal blooms: peak temperatures aren’t always important

July 5, 2018

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There are concerns that human impacts  on freshwater systems – particularly temperature increases linked to climate change and nutrient enrichment caused by run-off and pollution – are encouraging the spread of blue-green algae (cyanobacteria) capable of generating toxic blooms that threaten human and animal health.  One such case is the recent spread of Cylindrospermopsis raciborskii, […]

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 […]

More clarity on climate change

December 21, 2017

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Although climate change is warming many lakes around the world, there are big variations in their rate of temperature increase.  This variability is thought to be partly due to the fact that lakes differ widely in terms of water clarity, which is affected by factors such as land management, rainfall and changes in dissolved organic […]

Predatory fish control prey populations – but not when the prey are other fish

September 25, 2017

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Many lake studies have shown that predatory fish feeding on plankton or bottom-living invertebrates have a strong influence on the density, species composition and size structure of prey populations. Typically, there’s an inverse relationship between predator and prey populations, both in terms of  density and in mean body size.  However, there have been few reports […]