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It's no secret that the vast majority of Central Valley streams have been extensively modified in the relatively brief period since the California Gold Rush of the mid 1800s. However, it can still be hard to come to terms with the new reality of these waterways: although charismatic and popular native species, such as salmon and steelhead, still call the waters home (often only seasonally), these habitats are now numerically dominated by nonnative species that were either deliberately or inadvertently introduced. As discussed in a recently published article in the journal River Research and Applications, these modified habitats represent novel ecosystems that still exhibit characteristics of natural species communities, with defined predator-prey interactions, competition among species, and a food web based on primary production. However, the altered composition of such systems poses a significant challenge to resource managers attempting to maintain and increase suitable habitat for native species.
Waterways in arid climates, such as in California or the Mediterranean region, are often among the most significantly altered in the world. Reasons for this include the strong motivation to capture and store seasonally available water resources for use during drier times of the year, and the relative ease of modifying such waterways for storage, diversion, or flood conveyance during times of little or no discharge. These altered habitats, including storage reservoirs and waterways with a flow regime that differs dramatically from historical patterns, are quickly exploited by non-native fish species that often come to dominate novel aquatic ecosystems. The disruptive effect of introduced species on native species assemblages is well documented, and redeye bass (Micropterus coosae) in the Cosumnes River (pictured above), or Sacramento pikeminnow (Ptychocheilus grandis) in the Eel River, are prime examples of alien species that have thrived in their respective novel ecosystems to the detriment of native fishes.
Realizing that most aquatic ecosystems in California, particularly temporary rivers, have been modified to a degree that renders true restoration unfeasible in most cases, the article's author Dr. Peter Moyle refers to the concept of "reconciliation ecology" as the primary remaining and realistic management option. This concept recognizes that the altered state of many aquatic systems is not readily reversible, but that ecosystem change can be "guided" to maximize benefits to a defined group of desirable species. A prime example of reconciliation ecology in action is northern California's Putah Creek. This historically intermittent stream once supported a diverse assemblage of native fish species, which were able to over-summer in remnant pools or seasonally migrate to the creek from the Sacramento River. Following dam construction, a large section of the creek fell dry for extended periods of time, but is now actively managed to favor native fish species that have once more have come to dominate many sections of the stream (Kiernan et al. 2012). Alien species can still be found in Putah Creek and are likely to stay, but the approach of managing the stream as a novel aquatic ecosystem is truly a success of reconciliation ecology. Though it bears little resemblance to its historic state, Putah Creek now supports human uses as well as alien plant and animal communities that exist alongside native assemblages without displacing them.
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Recent Blog Post
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Moved in, taking over?
If you have spent much time  on a river, there is a good chance you may have stumbled across some river rocks that seem out of place. Maybe you pick one up and realize it has been sprayed with a coat of paint. You may not have thought much of it and tossed it back, or perhaps you took it home. Either way, it might surprise you to learn that such rocks play an important role in studying how sediment moves in relation to changes in river flow.
Gravel mobility or transport is important for salmon because it keeps the gravel oxygenated, removes algal growth, and decreases the amount of cementation that occurs when smaller particles fill the spaces between immobile gravel (Kondolf, 2000). On the other hand, too much gravel movement can decrease salmon spawning habitat by removing gravel from areas that are suitable for spawning and relocating it to deep pools that are unsuitable.
Quantifying the amount of gravel or sediment transport is a difficult task, but it's made easier with the help of colored rocks. Prior to a prescribed change in river flow, we collect stones from the river, dry them, and mark them with a bright color that can easily be spotted on the riverbed. Afterward, we return the rocks to the river and place them every few feet along a transect. We measure each rock and record its size and distance from the riverbank (Wilcock, 1997)... Read more >
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IN THE NEWS: Recent stories you might have missed...
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Work removes another barrier for migrating Calaveras River fish
Like many rural property owners, Vince and Linda Caprini value their privacy. Surely they wouldn't mind if the U.S. Fish and Wildlife Service, the state Department of Water Resources, the Stockton East Water District, and a bunch of guys with hard hats and excavators did some work on the river that passes through the middle of their walnut and cherry orchards. Read more >
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Shasta Chinook counts higher than 38-year average
Siskiyou Daily
 As salmon journey to their spawning grounds in the Klamath River's tributaries, preliminary counts are coming in higher than the 38-year average. The annual adult salmon escapement count occurs from about September to early January, according to Morgan Knechtle of the California Department of Fish and Wildlife. Knechtle and his team monitor the three weirs on Bogus Creek and the Shasta and Scott rivers,... Read more >
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'North Delta Arc' lifts hope for recovery of native fish
California Waterblog
Matt Young and Denise De Carion thought they had seen about all there is of fish communities in the Sacramento-San Joaquin Delta. They had surveyed nearly the entire web of channels using electrofishing boats in their years of assisting environmental researchers at UC Davis. In all their dozens of sampling runs, the story was the same: the Delta supports predominantly non-native species such as bass, catfish and bluegill sunfish - the garden variety found in almost any North American warm-water lake... Read more >
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Non-native trout stall Lahontan cutthroat restoration project
Statesman Journal
 Beginning Monday, biologists with the Oregon Department of Fish and Wildlife will be surveying 18 miles of McDermitt Creek looking for and removing non-native rainbow and brook trout. It's part of an eight-year effort to restore native Lahontan cutthroat trout to the remote watershed in southeast Oregon. It's not be the first time that the department has taken aim at non-native trout in McDermitt Creek, said Shannon Hurn, the district fish biologist in nearby Hines... Read more >
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Sperm swimming speed proves determining in salmon fertilization
FIS
When salmon spawn, males competing to fertilise eggs will win or lose based primarily on their sperm swimming speed, according to a collaborative study by researchers from the University of Otago and the University of Western Australia. In a recent study published in the Proceedings of The Royal Society B the researchers attempted to disentangle the relative importance of male, female and interactive effects on fertilisation success in this externally fertilising species... Read more >
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