River Flow By Design: Environmental Flows Support Ecosystem Services In Rivers Natural And Novel
Oct09

River Flow By Design: Environmental Flows Support Ecosystem Services In Rivers Natural And Novel

“When the sun peeped over the Sierra Madre, it slanted across a hundred miles of lovely desolation, a vast flat bowl of wilderness rimmed by jagged peaks. On the map the Delta was bisected by the river, but in fact the river was nowhere and everywhere, for he could not decide which of a hundred green lagoons offered the most pleasant and least speedy path to the Gulf.”

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Managing water with natural infrastructure: win-wins for people and wildlife

By Terence Houston, Science Policy Analyst The US Senate is moving forward with a new Water Resources Development Act, a comprehensive bill that authorizes funding for Army Corps of Engineers projects related to flood management, environmental restoration and other water resources infrastructure issues. The bipartisan legislation (S. 601) is sponsored by Senate Environment and Public Works Committee Chairwoman Barbara Boxer (D-CA) and Ranking Member David Vitter (R-LA). In light of this, the Consortium for Aquatic Science Societies recently held a congressional briefing that highlighted problems with aquatic invasive species and “natural infrastructure” solutions. David Strayer, Senior Scientist at the Cary Institute for Ecosystem Studies discussed the varied ways in which invasive species can harm ecosystems, recreation and tourism for communities living alongside major waterways. Invasive species cost the US economy $100 billion a year and cause significant lasting ecological changes, often hindering  recreation and leading to proliferation of less desirable  wildlife. Among the most costly of these is the zebra mussel, which has cost industry and business billions since its initial introduction to the United States several decades ago. The mussels damage boats, invade water treatment and power plants and clog pipes. Strayer also highlighted nutria, plant-eating rodents that can severely erode river banks,  leaving surrounding communities more vulnerable to floods; Japanese knotweed, which crowds out native plants and damages existing infrastructure; and didymo (commonly known as “rock snot”), which – in addition to its obvious aesthetic damage to otherwise scenic landscapes – alters streambeds and cuts out food sources for native aquatic species such as trout. Strayer noted that reservoirs, alteration of water flows in rivers and streams and fish stoking (which can unintentionally include contaminants and undesirable wildlife) can buttress proliferation of invasive species. He praised language in the new WRDA legislation that would establish a program to mitigate invasive species in the Columbia River Basin and manage invasive plants in the northern Rockies and urged support for an amendment recently incorporated into the bill from Sen. Kirsten Gillibrand (D-NY) that would seek to restrict invasive species from dispersing into the Great Lakes. Emma Rosi-Marshall, also with the Cary Institute on Ecosystem Services, focused her presentation on the general ecology of rivers. Many animals, including salmon and sturgeon, adapt their migration and breeding patterns on the dynamics of rivers. She also expanded on the important role of natural infrastructure such as wetlands and floodplains in mitigating floods and controlling erosion. Dams, while providing services such as water storage and power generation, can also disrupt wildlife migration and alter the manner in which sediment and nutrients are delivered along waterways. These alterations can impact fish abundance as well as...

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Looking to large tributaries for conservation gains

By Liza Lester, ESA communications officer Mississippi River Basin. Green tributaries have sufficient flow for large-river specialist fishes, and long stretches unobstructed by obstacles of civilization. Blue tributaries fall below a critical flow threshold. Yellow tributaries discharge enough water, but are blocked by dams. On big rivers like the Mississippi, the infrastructure of modern civilization – dams, locks, dikes, power plants, cities – has made life easier for people, but harder for fish and other denizens of the river. Restoration is a tricky problem. Economic reliance on these big rivers makes fundamental reversals like dam removals unlikely. Conservation laws and projects tend to be local, on the city or state level, and the river crosses many borders, complicating the restoration picture. Large Tributaries have under-appreciated potential to compensate for habitat loss on the major concourses of the Mississippi Basin, say Brenda Pracheil and colleagues at the University of Wisconsin, Madison, in the April issue of Frontiers in Ecology and the Environment. The Platte, for example, has 577 kilometers of free-flowing, relatively intact habitat. It feeds into the heavily altered Missouri, a large mainstem river in the Mississippi Basin, and harbors many of the same fishes. Pracheil found a correspondence between the volume rate of water flow and the presence of 68 large-river fishes, including paddlefish, blue catfish, and silver chub, most of which are threatened. A steep threshold separates tributaries with large-river fish from those without; 166 cubic meters per second is big enough for roughly 80% of large river specialist species. Below the threshold, almost none of these species are around. Pracheil says this threshold could be used to target tributaries for conservation attention. Existing regulatory structures don’t allow improvements on tributaries to count toward mainstem restoration mandates. The UW scientists argue that more flexibility could, in some cases, provide a better return on investment of conservation dollars, complementing efforts on the larger rivers downstream. Learn more on the University of Wisconsin Center for Limnology blog and on the UW’s news site. Pracheil, B., McIntyre, P., & Lyons, J. (2013). Enhancing conservation of large-river biodiversity by accounting for tributaries Frontiers in Ecology and the Environment, 11 (3), 124-128 DOI:...

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