Browsing All Posts filed under »fish«

How fish negotiate culverts

March 27, 2017

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While culverts are designed to facilitate the movement of water by allowing it to flow under roads or other obstructions, they can place physiological and/or behavioural restrictions on the movements of fish. Although several studies have considered the implications of culvert design for fish passage, surprisingly few have tried to identify the factors that influence […]

How fishing changes catchability

March 27, 2017

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The bolder members of a fish population – often defined as those most willing to continue to forage under the threat of predation – tend to be relatively exploratory, aggressive, territorial, and enjoy higher rates of food intake and specific growth than more timid individuals. However, their larger size makes bold fish more vulnerable to […]

Tree cover makes for lower fish diversity

March 27, 2017

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A pervasive feature of lowland streams, especially in areas where land has been cleared for agriculture or urban development, is a decrease in forested cover from the headwaters to the mouth. The presence or absence of streamside tree cover has a profound influence on stream ecology. Streams running through undisturbed forests typically contain large woody […]

Predators concentrate on current-concentrated prey

December 13, 2016

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In marine environments, recirculating eddies, upwellings and downwellings play an important role in concentrating plankton in small areas, a process that attracts predators such as fish, mammals and birds and boosts ecological productivity significantly above background levels. However, much less is known about the ways in which physical processes may concentrate organisms and intensify food-web […]

Low biodiversity in productive lakes

December 13, 2016

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The over-supply of nutrients to lakes (through pollution, for example) stimulates the growth of plant plankton, which blocks light from reaching bottom-dwelling algae and higher plants. Therefore, nutrient excess has the potential to reduce habitat diversity and the associated biodiversity of animal plankton, macroinvertebrates and fish. An international team of biologists looked at the relationship […]

Male fish copy and mislead their rivals

December 13, 2016

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Because the numbers of sexually receptive females are relatively low in wild guppy populations, male fish incur a high cost in searching for suitable mates. However, such costs can be reduced if males are able to collect information on females by observing their sexual interactions with other males. To assess this possibility, preference experiments were […]

Restoration ecology: are we forgetting top-down control?

June 1, 2016

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Authors of a recent review article argue that restoration ecologists rely heavily on the assumption that natural communities are controlled by bottom-up processes (i.e., the upward transfer of nutrients and energy from plants to animals), but tend to ignore the complementary effects of top-down control by animals on nutrient cycling and the abundance and diversity […]