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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 […]
September 28, 2021
Comments Off on Aquatic insects on the decline
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 […]
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 […]
March 13, 2021
Comments Off on Underwater cameras spot rare fish
When species are rare they can remain undetected at a given site even when they’re actually there. However, occupancy modelling can be used to adjust for imperfect detection and assess whether a species is likely to be present. Occupancy models allow for the effects of habitat variation on detection probability and they’ve been widely used […]
March 31, 2020
Comments Off on Climate change: weighing up the pluses and minuses
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 […]
September 23, 2019
Comments Off on Invasive species counter evolutionary responses to fishing
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 […]
July 5, 2018
Comments Off on Fish life histories: filling in the gaps
Estimates of life history parameters such as age at maturity, maximum body size and rates of growth and mortality play a crucial role in understanding and managing animal populations, but in the case of many species they’re lacking or poorly measured. Fortunately however, compilations of existing estimates now exist, and these databases open up opportunities […]
June 19, 2017
Comments Off on Human impacts on ecological connectivity
Ecological connectivity – the exchange of organisms between habitat patches or subpopulations – has an influence on many key processes, including population dynamics, nutrient flux, disease transmission, species invasions, food-web interactions, genetic isolation and the maintenance of biodiversity. A recent study reviewed ways in which graph theory has been used to investigate how human activities […]
December 13, 2016
Comments Off on Top predator boosts species richness – but not in alien ecosystems
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 […]
June 1, 2016
Comments Off on Remote surveillance:monitoring fish populations
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 […]
Freshwater Research News 
March 26, 2022
Comments Off on A lesson from fish: don’t let stress ruin procreation