Catherine Puckett, USGS ( Phone: 352-377-2469 );
BOZEMAN – Pallid sturgeon come from a genetic line that has lived on this planet for tens of millions of years; yet it has been decades since anyone has documented any of the enormous fish successfully producing young that survive to adulthood in the upper Missouri River basin.
Now, fisheries scientists with the U.S. Geological Survey, Montana State University and the U.S. Fish and Wildlife Service have shown why, detailing for the first time the biological mechanism that has caused the long decline of pallid sturgeon in the Missouri River and led to its being placed on the endangered species list 25 years ago.
In a paper published this week in the journal Fisheries, the scientists show that oxygen-depleted dead zones between dams in the upper Missouri River are directly linked with the failure of endangered pallid sturgeon hatched embryos to survive to adulthood.
“This research is a notable breakthrough in identifying the reason why pallid sturgeon in the Missouri River have been declining for so many decades,” said Suzette Kimball, acting director of the USGS. “By pinpointing the biological mechanism responsible for the species’ decline, resource managers have vital information they can use as a focus of pallid sturgeon conservation.”
“We certainly think this is a significant finding in the story of why pallid sturgeon are failing to recruit in the upper Missouri River,” said Christopher Guy, the assistant unit leader with the USGS Montana Cooperative Fishery Research Unit and the MSU professor who was the lead author on the paper. “We’re basically talking about a living dinosaur that takes 20 years to reach sexual maturity and can live as long as the average human in the U.S. After millions of years of success, the pallid sturgeon population stumbled and now we know why. From a conservation perspective, this is a major breakthrough.”
The study is the first to make a direct link among dam-induced changes in riverine sediment transport, the subsequent effects of those changes on reduced oxygen levels and the survival of an endangered species, the pallid sturgeon.
“This research shows that the transition zone between the freely flowing river and reservoirs is an ecological sink – a dead zone – for pallid sturgeon,” Guy said. “Essentially, hatched sturgeon embryos die in the oxygen-depleted sediments in the transition zones.”
Guy said fisheries biologists long suspected that the Missouri River’s massive reservoirs were preventing hatched embryonic pallid sturgeon from surviving to the juvenile stage. But early attempts to tie the problem to low levels of dissolved oxygen were unsuccessful.
“The reason for that is we hadn’t sampled deep enough,” Guy said. “It wasn’t until we sampled water down at the bottom, where those sediments are being deposited, that we found there was no dissolved oxygen. Because hatched pallid sturgeon embryos are negatively buoyant, they tend to sink into that hostile environment.”
“The lack of oxygen is a function of high microbial activity in the sediment laden area,” said co-author Eric Scholl, a Ph.D. student at Montana State University and a co-author on the study.
Hilary Treanor, an MSU research associate working with Guy, said they were able to show just how hostile these transition zones between riverine environment and reservoir could be to hatched sturgeon embryos.
In experiments at the U.S. Fish and Wildlife Fish Technology Center in Bozeman with coauthors Molly Webb, Kevin Kappenman, and Jason Ilgen, Treanor said different aged hatched embryos were treated with water of varying levels of dissolved oxygen. The lowest level they could recreate – 1.5 milligrams of oxygen per liter of water – was still higher than samples pulled from the bottom at the upper end of Fort Peck Reservoir.
At those depleted levels, the hatched sturgeon embryos suffered almost immediately.
“We saw changes in their behavior fairly quickly. They became disoriented and weren’t able to move the way they should have,” Treanor said. “Within an hour we started to see mortality. By the end of the experiment they were all dead.”
"Pallid sturgeon, native to the Missouri and Mississippi rivers, were listed as an endangered species in 1990. The species has a lifespan of as much as a century. According to the U.S. Fish and Wildlife Service, fewer than 175 wild-spawned pallid sturgeon – all adults – live in the free-flowing Missouri River above Lake Sakakawea. Since 1990, not a single wild-spawned pallid sturgeon is known to have survived to a juvenile, despite intensive searching.
In the past 5 years, researchers identified the most important reason for pallid sturgeon population declines in the Upper Missouri River: the lack of survival of naturally produced hatched sturgeon embryos.
Guy said this most recent study of sturgeon built on research conducted by USGS fisheries biologist Patrick Braaten, which demonstrated not enough available drift distance exists between the reservoirs for hatched pallid sturgeon embryos before entering the reservoirs in the upper Missouri River.
Before dams, hatched pallid sturgeon embryos would drift for hundreds of miles, eventually settling out of the river’s current in areas with low flow where they matured enough to negotiate the river’s flow.
“This team has shown how much we can do when we have a collaboration between MSU, USGS and world-renowned reproductive physiologists Molly Webb and Kevin Kappenman with the U.S. Fish and Wildlife Service,” Guy said. “In the process of doing this research, we’ve trained a dozen MSU graduate students and a number of undergraduate field and lab techs.”
Given what the new research shows about how no oxygen is available to hatched pallid sturgeon embryos, the authors of the paper propose that officials will need to consider innovative approaches to managing Missouri River reservoirs for pallid sturgeon conservation to have a chance. It also could provide some guiding principles for the construction of new dams around the world, Guy said.
ANCHORAGE, Alaska Melting glaciers are not just impacting sea level, they are also affecting the flow of organic carbon to the world’s oceans, according to new research that provides the first ever global-scale estimates for the storage and release of organic carbon from glaciers.
The research, published in the Jan. 19 issue of Nature Geoscience, is crucial to better understand the role glaciers play in the global carbon cycle, especially as climate warming continues to reduce glacier ice stores and release ice-locked organic carbon into downstream freshwater and marine ecosystems.
“This research makes it clear that glaciers represent a substantial reservoir of organic carbon,” said Eran Hood, the lead author on the paper and a scientist with the University of Alaska Southeast (Juneau). “As a result, the loss of glacier mass worldwide, along with the corresponding release of carbon, will affect high-latitude marine ecosystems, particularly those surrounding the major ice sheets that now receive fairly limited land-to-ocean fluxes of organic carbon.”
Polar ice sheets and mountain glaciers cover roughly 11 percent of the Earth’s land surface and contain about 70 percent of Earth’s fresh water. They also store and release organic carbon to downstream environments as they melt. Because this glacier-derived organic carbon is readily metabolized by microorganisms, it can affect productivity in aquatic ecosystems.
“This research demonstrates that the impacts of glacier change reach beyond sea level rise,” said U.S. Geological Survey research glaciologist and co-author of the research Shad O’Neel. “Changes in organic carbon release from glaciers have implications for aquatic ecosystems because this material is readily consumed by microbes at the bottom of the food chain.”
Due to climate change, glacier mass losses are expected to accelerate, leading to a cumulative loss of nearly 17 million tons of glacial dissolved organic carbon by 2050 — equivalent to about half of the annual flux of dissolved organic carbon from the Amazon River.
These estimates are the first of their kind, and thus have high uncertainty, the scientists wrote, noting that refining estimates of organic carbon loss from glaciers is critical for improving the understanding of the impacts of glacier change. The U.S. Department of the Interior Alaska Climate Science Center and USGS Alaska Science Center plan to continue this work in 2015 and beyond with new efforts aimed at studying the biophysical implications of glacier change.
This project highlights ongoing collaboration between academic and federal research and the transformative results that stem from such funding partnerships. Other institutions involved in the research include Ecole Polytechnique Fédérale de Lausanne and Florida State University.
The work was supported by the National Science Foundation, the USGS Alaska Science Center, and the DOI Alaska Climate Science Center. The Alaska Climate Science Center provides scientific information to help natural resource managers and policy makers respond effectively to climate change.
Newly released US Topo maps for Nebraska now feature trails provided to the USGS through a “crowdsourcing” project operated by the International Mountain Biking Association (IMBA). Several of the 1,376 new US Topo quadrangles for the state now display trails along with other improved data layers such as map symbol redesign and new road source data.
"As an avid cyclist I look forward to exploring the new US Topo maps for bike trails as I plan my trips," said Jim Langtry, National Map Liaison for Nebraska. "I look forward to the expansion of the trail network and hope this encourages the crowdsourcing effort to add and maintain trails for future updates. It would be great to see the Cowboy Trail, the nation’s longest rails-to-trail trek along the northern tier of Nebraska, included on the next update. You can hike, bike, or horseback ride a total of 195 miles on the completed trail from Norfolk to Valentine. Enjoy the small towns along the way, beautiful scenery and pristine air on the Cowboy Trail."
For Nebraska residents and visitors who want to explore the rolling “cornhusker” landscape on a bicycle seat, the new trail features on the US Topo maps will come in handy. The data is provided through a partnership with IMBA and MTB Project. During the past two years, the IMBA has been building a detailed national database of mountain bike trails with the aid and support of the MTB Project. This activity allows local IMBA chapters, IMBA members, and the public to provide trail data and descriptions through their website. MTB Project and IMBA then verify the quality of the trail data provided, ensure accuracy and confirm that the trail is legal. This unique crowdsourcing venture has increased the availability of trail data available through The National Map mobile and web apps, and the revised US Topo maps.
These new maps replace the first edition US Topo maps for Nebraska and are available for free download from The National Map, the USGS Map Locator & Downloader website , or several other USGS applications.
To compare change over time, scans of legacy USGS topo maps, some dating back to the late 1800s, can be downloaded from the USGS Historical Topographic Map Collection
For more information on US Topo maps: http://nationalmap.gov/ustopo/New version of the North Platte, Nebraska US Topo quadrangle: 2014, with orthoimage turned on. (1:24,000 scale) (high resolution image 1.2 MB) 1902 historic version of the North Platte, Nebraska US Topo quadrangle at 1;25,000 scale. (high resolution image 1.8 MB)