Browsing All Posts filed under »fish«

Why are there so many crocodiles in tropical waterholes?

March 26, 2018

0

Transfers of organic material from one aquatic environment to another (for example, through flood pulses or animal migrations) allow productive donor ecosystems to subsidise less productive habitats. However, there are big variations in the extent to which different animal species depend on production subsidies.  To explore such differences, Australian researchers collected a wide array of […]

Freshwater fish surveys: direct observation works well

March 26, 2018

0

Although surveys of freshwater fish populations often rely on electrofishing, it’s difficult to use this technique in some habitats. An alternative sampling method is direct observation by snorkelling, an approach often applied in marine environments.  While comparisons of the sampling efficiency of electrofishing and snorkelling have been carried out, most of them have been based […]

Guppies know their way around

March 25, 2018

0

Rats, mice and other rodents can quickly learn to solve complex spatial problems such as mazes consisting of sequences of left-right turns. Although the spatial abilities of rodents may be the result of their burrow-dwelling existence, it’s also possible that such abilities are widely shared by other vertebrates. Fish are known to have well-developed spatial […]

A mature approach to growth data

March 25, 2018

0

The age at which an animal matures is a key life history trait with implications for ecology, evolution and population dynamics, but data on maturation can be costly to collect. However, in many animals growth occurs in two phases, with a change-point at maturity, which means that it’s sometimes possible to estimate the maturation age […]

Benefits and costs of habitat complexity

December 21, 2017

Comments Off on Benefits and costs of habitat complexity

The fact that biodiversity tends to be higher in structurally complex habitats suggests that, on balance, the fitness-related advantages of habitat complexity outweigh the disadvantages.  Possible advantages include a greater supply of locations where animals can hide from predators and conserve their energy, and higher abundances of potential prey.  Also, in complex habitats less energy […]

Once more from the top

December 21, 2017

Comments Off on Once more from the top

Top-down trophic cascades are population-level effects transmitted along food chains, from consumers down to primary producers.  In a typical three-level food chain the loss of top predators (for example, as a result of human exploitation) allows herbivore populations to increase, which in turn reduces populations of algae or higher plants.   However, few studies have considered […]

Why are cold water fish bigger?

December 21, 2017

2

In a wide range of animal groups, maximum body sizes tend to be higher in temperate and polar species than in those living closer to the equator, and there’s been a lively debate about the underlying reasons for this trend.  French and Bolivian scientists  investigated possible explanations by using a family of freshwater fish (the […]