Browsing All Posts filed under »fish«

When drought eliminates fish…

March 30, 2019

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  Droughts can lead to lasting changes in the condition of wetlands.  For example, as drying occurs water levels drop and light penetration improves, which allows aquatic plants in the seed bank to germinate.  By stabilizing sediments, outcompeting algal plankton and  providing refuge to zooplankton grazers, newly established stands of aquatic plants can cause originally […]

Rapid advancement depends on schooling

March 30, 2019

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  Research suggests that, as well as reducing the risks of predator attack, schooling behaviour can help fish to improve their swimming efficiency.  However, because most studies of swimming performance have been carried out on individual fish, the swimming abilities of schooling species may have been underestimated.  Typically, swimming performance experiments are carried out in […]

Getting river history right

March 30, 2019

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  Information on past climate patterns can prove invaluable when assessing the responses of freshwater ecosystems to environmental change, but what are the implications for ecological understanding if beliefs about climate history are incorrect?  This question has been explored by scientists who used the Murray River, Australia’s largest river system, as a case study.  Hydrologically, […]

How rivers befriend seabirds

January 14, 2019

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Where rivers flow into the ocean, the density fronts between fresh and salt water masses help to concentrate zooplankton and larval fish, making them more available to predators.  For example, freshwater discharge from the Columbia River creates a large brackish plume that can stretch for hundreds of kilometres along the North American coast, and nutrient […]

A landmark study

January 14, 2019

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Animals use a range of strategies to return to refuge areas, foraging patches and mating sites, but little is known about the ways that navigation is affected by different types of sensory information.  Zoologists in Oxford, U.K. tested the ability of elephantfish (Gnathonemus petersii) – which are capable of electrolocation as well as visual detection […]

Understanding how fish benefit from river restoration

January 14, 2019

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Although relationships between fish traits and environmental factors are well known, there have been few attempts to use fish traits to interpret the outcomes of stream restoration projects.  German scientists set out to do this by analyzing  data from a tributary of the Rhine River, which had a long history of channelization, bank fixation, riparian […]

Top-down control varies within a species

January 14, 2019

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  Because consumer species can impose strong top-down effects on the structure and functioning of aquatic ecosystems, the loss or replacement of apex species may lead to dramatic alterations to the food web.  But can different forms of the same consumer species be sufficiently distinct that the replacement of one form by another triggers a […]