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Because large-bodied animal species tend to have a higher than average extinction risk, there are concerns that freshwater megafauna (species with body weights over 30 kg) are relatively vulnerable to human-induced disturbances such as reduced river flows, habitat fragmentation and pollution. In the 40 years leading up to 2012, global populations of freshwater megafauna declined […]
March 26, 2022
Comments Off on A lesson from fish: don’t let stress ruin procreation
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 […]
December 14, 2021
Comments Off on Lake management: are tipping points real?
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 […]
December 14, 2021
Comments Off on Invasive fish species take over in Singapore
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 […]
December 14, 2021
Comments Off on Gene flow in complex river systems
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 […]
September 28, 2021
Comments Off on In-stream wood increases fish abundance
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. […]
September 28, 2021
Comments Off on How flowing water affects the schooling of fish
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 […]
June 7, 2021
Comments Off on What do bioindicators really indicate?
There have been many attempts to find environmental measures that can be used as reliable indicators of disturbance in freshwater ecosystems, and proposed measures are often based on features of fish and macroinvertebrate communities, such as species richness, diversity, feeding styles and life history patterns. While such metrics should ideally be robust enough for general […]
June 7, 2021
Comments Off on How rivers regulate fish numbers
Recruitment processes, which determine the number of young animals entering a population each year, are central considerations in our attempts to understand fluctuations in abundance. Although recruitment has been a key focus of fisheries scientists for many years, most of their work has involved marine fish species, and there’s been no fully integrated and comprehensive […]
June 7, 2021
Comments Off on Sound directions for the freshwater sciences
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 […]
Freshwater Research News 
March 26, 2022
Comments Off on Freshwater megafauna under threat