Donita Turk ( Phone: 785-832-3570 );
Evaluations of water nutrient ratios suggest that concentrations of a class of cyanobacteria toxins (cyanotoxins), called microcystins, tended to decrease as the total nitrogen to total phosphorus (TN:TP) ratio increased.
Nitrogen addition and phosphorus removal treatments were used to control nutrient ratios in confined experimental chambers in Willow Creek Reservoir, Ore., over two consecutive summers.
Two scientific articles on this research, recently published in the scholarly journal Lake and Reservoir Management, were completed as a joint partnership between the University of Idaho and the U.S. Geological Survey. The study supports previous work done on nutrient ratios and microcystins. The articles, entitled "Experimental manipulation of TN:TP ratios suppress cyanobacterial biovolume and microcystin concentration in large-scale in situ mesocosms," and "Experimental additions of aluminum sulfate and ammonium nitrate to in situ mesocosms to reduce cyanobacterial biovolume and microcystin concentration," are available online.
"This does not necessarily mean that increasing nitrogen in a lake will decrease cyanotoxins," said USGS scientist Ted Harris. "This was a study done in one location, and warrants further research."
This case study suggested that a TN:TP ratio of 75:1 or larger resulted in the growth of green algae instead of toxic cyanobacteria. Toxic cyanobacteria can produce toxins such as microcystins which can be harmful to aquatic life, terrestrial animals, and humans. Cyanotoxin exposure has led to illness in wildlife, livestock, and humans and can result in death in severe exposure cases.
Results from this research could help manage cyanobacteria toxin production; however these approaches need to be studied more extensively in whole-lake settings to fully understand the implications of using these approaches to control cyanobacteria toxin production balanced against other potential environmental harm and socio-economic conditions.
For more information:
- USGS Kansas Algal Toxin Research Website
- USGS Nutrients National Synthesis Project
- USGS Toxic Substances Hydrology Program
A new USGS study quantifies change in fish diversity in response to streamflow alteration in the Tennessee River basin.
The USGS study highlights the importance of the timing, magnitude, and variability of low streamflows and the frequency and magnitude of high streamflows as key characteristics critical to assessing how fish communities change in response to streamflow alteration. This study was completed using fish community data collected by the Tennessee Valley Authority, and predictions of streamflow characteristics at more than 600 locations.
The Tennessee River basin is one of the richest areas of aquatic diversity in the country, if not the world. However, expanding urban development, more than 600 privately held small dams on medium to small streams, and withdrawal of more than 700 million gallons of water each day threaten this diversity. Understanding the effect of streamflow alteration on aquatic ecology is increasingly important as change in land use and human population are projected.
One of the examples from the study shows that as maximum October streamflow deviates outside reference conditions by approximately 6 cubic feet per second per square mile, fish diversity may decline by almost nine species in the Blue Ridge ecoregion of eastern Tennessee and western North Carolina. Results such as this were identified across the Blue Ridge, Ridge and Valley, and Interior Plateau ecoregions for 11 categories of fish and will help resource managers identify when streamflow alteration may result in too much ecological degradation.
“Managing river flows to meet the needs of our growing communities and economies will become increasingly challenging in the future”, said Sally Palmer, director of science for The Nature Conservancy in Tennessee. “Maintaining our rivers to support an abundance of natural wildlife, including our native fish, is an important goal as well. Studies like these give us better information to make management decisions which more effectively balance all the demands placed on our river resources.”
The National Park Service, responsible for the protection and management of Big South Fork National River and Recreation Area and the Obed Wild and Scenic River in Tennessee, has a need to assess potential impacts to the resources they are charged with protecting. “This research enhances our ability to respond to current development pressures and serves as the foundation to develop a decision support tool to address future water resource issues” said Jeff Hughes, hydrologist with the NPS.
Additional information regarding environmental flows research in the Tennessee River basin can be found online. This work was completed as part of the USGS Cooperative Water Program in collaboration with the Tennessee Wildlife Resources Agency, Tennessee Department of Environment and Conservation, and The Nature Conservancy.
A new online, interactive sediment data portal represents the best available compendium of suspended sediment data for streams and rivers across the Nation.
Watershed managers, policy-makers, researchers, and the public can use the portal to access suspended sediment information at over 4,900 sites.
Ever since sediment samples were first collected in 1889 by pioneering engineer Frederick Newell and 14 of his colleagues on the Rio Grande River at Embudo, N.M., the U.S. Geological Survey has continued to collect and record information on sediment transport in streams and rivers across the Nation.
Too much sediment can harm aquatic life and reduce the storage capacity of reservoirs affecting water supply and flood storage. In some instances, too little sediment can also be an issue. For example, decreased amounts of sediment in the lower Mississippi Basin have been identified as the primary reason for the loss of thousands of square miles of wetlands off the Louisiana coast.
The portal provides easy access to valuable long-term data sets that can be useful in assessing how landscape modifications are affecting sediment transport in streams and rivers. Information on sediment concentrations and grain size can help identify appropriate and cost-effective sediment monitoring methods. Sediment data and ancillary data on streamflow condition, sediment grain size, sampling method, and landscape condition are also available for download within the portal.
USGS Data Series Report DS776 describes the methods used to recover, quality control, and summarize USGS suspended-sediment data in the portal through 2010. In addition to daily and discrete suspended sediment sampling, the USGS, in cooperation with numerous local, state, and other federal agencies, currently operates 424 real-time turbidity sensors across the Nation. These data are available at USGS Water-Quality Watch.
Sediment monitoring and real-time turbidity monitoring is supported by the USGS National Stream Quality Accounting Network, Cooperative Water Program, and the National Water-Quality Assessment Program. The USGS also continuously monitors streamflow at over 8,000 of the nation's streams on a real-time basis. These data are available at USGS Current Streamflow Conditions.