Gravel-Bed Rivers Very Important for Aquatic, Avian and Terrestrial Species

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Credit: Photo by Harvey Locke

Rivers are the prime necessity for any ecosystem to flourish and there is no scientific proof required for this; however, when it comes to gravel-bed rivers located in mountainous regions, they are one of the most complex rivers known and a new study has looked into how the complexity of these rivers benefit aquatic, avian and terrestrial species in the surrounding areas.

Researchers from the US and Canada showed through their study published in Science Advances how broad valleys coming out of glaciated mountains provide highly productive and important habitat for a large diversity of species. For their study scientists looked at the full continuum of species and processes supported by gravel-bed rivers, from microbes to bull trout and from elk to grizzly bears.

Gravel-bed river floodplains support more than half the region’s plant life in the entire Yellowstone to Yukon region, which stretches from Yellowstone National Park north into Canada’s northern Yukon Territory. Further, more than 70 per cent of the region’s bird species use the river plains while deer, elk, caribou, wolves and grizzly bears use the floodplains for food, habitat and important migration corridors.

Researchers found that these river systems are complex because of their ever-changing features i.e. gravel and cobbles that move with flooding, scoured and changing river channels, and a constant flow of water into and out from the gravels of the river. This water extends across the U-shaped valley bottom often hundreds of meters or more from the river channel, and supports a complex food web that includes aquatic species as well as a vast diversity of avian and terrestrial species. These processes are driven by the river’s changes in volume throughout the year.

The gravel-bed rivers also provide essential connectivity across the landscape for both terrestrial and aquatic organisms, which is critical in a time of climate change.

These floodplains also are some of the most endangered landforms worldwide. Human settlement, agriculture, industry and transportation often occur in flat, productive river valleys. While there are many protected areas in the northern Rocky Mountains of the United States and Canada such as Yellowstone and Banff national parks, humans have altered the structure and function of the gravel-bed river floodplains outside, as well as inside, these protected areas.

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