Browsing All Posts filed under »behaviour«

Dams challenge platypus populations

March 26, 2022

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The construction of dams has many adverse effects on river hydrology and ecology.  Dams limit animal movements and reduce the cover of riparian vegetation, which leads to bank erosion and the filling of stream pools with sediment.  Dam-related impacts have been documented for many types of riverine animals, including macroinvertebrates, amphibians and waterbirds.  However, the […]

The net effect: caddis flies and streambed flow

March 26, 2022

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The beds of streams are dynamic interfaces where water, nutrients and living organisms move between surface and sub-surface environments, and streambed permeability has a significant influence on processes such as nitrogen cycling and organic matter decomposition.  Although the physics of streambed exchange are well understood, interactions between physical and biological processes have received relatively little […]

A lesson from fish: don’t let stress ruin procreation

March 26, 2022

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Annual fishes live in temporary ponds that dry out completely in summer.  As a result they have the shortest life spans of all vertebrates: after a few months they perish and the next generation depends on the survival of their drought-proof eggs, which hatch when the pond is eventually flooded.  As the shallow ponds dry […]

Invasive fish species take over in Singapore

December 14, 2021

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Cichlids make up a large family of freshwater fish with centres of native distribution in Africa and South America.  Cichlid species vary widely in terms of feeding habits, reproductive strategies and environmental tolerances, and their capacity for adaptive radiation in areas such as the African Great Lakes is legendary. Unfortunately, with human assistance many of them […]

Gene flow in complex river systems

December 14, 2021

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Understanding how variations in habitat connectivity affect gene flow and possible genetic isolation in river systems is tricky because of the unique structural features of stream ecosystems, which are notoriously difficult to model: unlike terrestrial landscapes, they are linear branching networks, which means that overland distance is often a poor indicator of the correlation between […]

In-stream wood increases fish abundance

September 28, 2021

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Although fallen woody material provides many freshwater fish species with essential habitat for feeding, refuge and spawning, a lot of submerged wood has been removed from rivers in an attempt to prevent floods and improve boat passage. However, current best management practice is to reverse this historical trend by reintroducing wood to rivers and streams.  […]

How flowing water affects the schooling of fish

September 28, 2021

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In many species of fish, individuals group together in shoals or schools to benefit from shared information – for example, on food availability or the presence of predators.  There’s also evidence that fish gain hydrodynamic benefits by taking up certain positions relative to other individuals, but not much is known about how flowing water affects […]

Aquatic insects on the decline

September 28, 2021

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Although there’s growing evidence that species in many animal groups, including insects, amphibians, aquatic invertebrates and birds, are experiencing dramatic and widespread declines in abundance, identifying the factors driving these changes is a major challenge because most ecosystems are affected by several stressors at the same time.  In addition, long-term data sets on species abundance […]

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 […]

Sound directions for the freshwater sciences

June 7, 2021

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A recent issue of the journal Freshwater Biology was devoted to the emerging field of ecoacoustics (the study of the ecological role of sounds), an exciting area with many applications in freshwater science.  So far, passive acoustic monitoring has been used mainly in terrestrial and marine environments, but recent studies reveal that inland waters support […]