Browsing All Posts filed under »reproduction«

Freshwater megafauna under threat

March 26, 2022

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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 […]

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 […]

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 […]

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 […]

How rivers regulate fish numbers

June 7, 2021

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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 […]

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 […]

What determines leaf length in aquatic plants?

March 13, 2021

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Several genera of aquatic plants have very long strap-like leaves.  Leaf lifespan and growth are known to be influenced by plant life history and reproductive strategies, but there have been few attempts to understand the factors that regulate leaf size in aquatic plants.  Terrestrial plants have been better studied in this respect, but environmental factors […]

River resilience and the three Rs

June 25, 2020

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River ecosystems are impacted by a wide range of disturbances.  Floods and droughts are the most important types of natural disruption, while human-induced impacts include pollution, habitat degradation and climate change.   An ecosystem’s ability to recover from disturbance – its resilience – is a key concern in river management.  A multinational research team has developed […]

Climate change: weighing up the pluses and minuses

March 31, 2020

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Because the vulnerability of a species to climate change can vary with life stage, there’s a need to consider the challenges and opportunities presented by climate warming across the whole lifetime.  This is particularly important in the case of species with complex life cycles, or where juveniles and adults of the same species inhabit different […]

Invasive species counter evolutionary responses to fishing

September 23, 2019

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Harvesting by humans can have far-reaching effects on the population structure of exploited species and the dynamics of food webs – for example, fishing often removes the largest and oldest individuals in a population disproportionately, which selects for animals that grow faster and mature earlier.  Harvesting may also interact with changes in environmental conditions, but […]