Everglades National Park, Fla.— Invasive Burmese pythons in South Florida are able to find their way home even when moved far away from their capture locations, a finding that has implications for the spread of the species.
A multi-organizational team of scientists found that when six Burmese pythons were relocated 13-22 miles from their capture locations, the snakes headed straight back home, navigating to within 3 miles of their original capture locations in Everglades National Park.
"Previous studies have shown that many snakes lack the ability to home, yet this study provides evidence that Burmese pythons are capable of homing after they have been displaced --- and they are able to do so at a scale previously undocumented for any snake species," said Shannon Pittman, lead author of the study and a postdoctoral fellow at Davidson College in North Carolina. "Understanding this large-scale navigational ability is critical to understanding the ability of Burmese pythons to expand their geographic range," Pittman added.
To find your way home requires a map sense on the part of the animal, which allows the animal to determine its position in relation to a goal; and a compass sense, which requires access to a reliable compass to maintain orientation toward the goal. The relocated snakes moved faster and straighter than snakes that were not relocated, demonstrating that Burmese pythons have navigational map and compass senses.
The relocated snakes also appeared to use local cues from their release site to determine their position relative to home. Potential cues underlying the map sense in pythons may be olfactory or magnetic that change predictably through space. The compass aspect of their navigational ability could be accomplished through the use of magnetic, celestial, olfactory or polarized light cues, all of which generate a reliable compass sense.
"The snakes maintained their oriented movement over the course of a relatively long time, between 94 and 296 days," said Kristen Hart, a USGS researcher and study coauthor. "This indicates that not only do pythons keep their long-term movement goal in mind, but also that they were highly motivated to get back home."
These findings have implications for management and conservation of the species, the study authors emphasized. Animals that are adept at navigating and homing are better able to exploit resources that are relatively far away, widely spaced or seasonally variable. These abilities also reduce risks associated with searching potentially hostile or unfamiliar areas because the dispersing snakes can always return to a safe location.
"Understanding navigation in invasive species improves the ability to control populations and limit dispersion," said Hart. "For example, the fine-tuned navigational capacity that the pythons exhibited may lower their risk when they move to and explore new areas."
This research is useful for resource managers because it has implications for python movement behavior at the edges of the invasion front where there is a need for containment, Pittman said.
"Invasive exotic reptiles continue to challenge agencies charged with protecting the health of south Florida ecosystems," said Everglades National Park Superintendent Dan Kimball. "Continued research like this on the invasive exotic Burmese python is critical so that we can make better informed management decisions and move closer to containment of this species that has adapted to this environment."
The invasive Burmese python is an apex predator in the Everglades that became established in Florida several decades ago. The largest snakes removed from the Everglades have exceeded 18 feet and 150 pounds. Snakes of this size are capable of ingesting large prey like adult deer and alligators.
"Homing of invasive Burmese pythons is South Florida: evidence for map and compass senses in snakes" by S.E. Pittman, K.M. Hart, M.S. Cherkiss, R.W. Snow, I. Fujisaki, B.J. Smith, F.J. Mazzotti, and M.E. Dorcas, is published in the journal Biology Letters. The study can be accessed online.
ST. PETERSBURG, Fla.-- A first of its kind study has the potential to impact future regulatory decisions on disinfection practices for water prior to its recharge or following its storage in the Floridan Aquifer.
The U.S Geological Survey report found that coliform bacteria die off faster in a regional aquifer system than was previously known, though a small percentage survives. One of the state's regulatory criteria for ensuring the quality of recharged water is whether it contains coliform bacteria.
Aquifer storage and recovery facilities have been used in Florida for about 30 years to store large volumes of water over long periods of time, increasing water supply during seasonal and multi-year droughts. Potable water, treated and untreated groundwater, partially treated surface water and reclaimed water is recharged into zones of the Floridan Aquifer and later recovered when needed.
"Although it is commonly believed that bacteria are few in number and mostly inactive in the lower zones of the Floridan aquifer system, we found relatively high numbers of bacteria that are alive and active," said USGS microbiologist, John Lisle. "However, when we looked specifically at coliform bacteria, we found that they died off at higher rates in the aquifer than was previously known." Understanding that coliform bacteria die off faster than previously known has the potential to shape the standards or monitoring requirements that are set.
In addition to the coliform die off data, this study is the first to characterize both the geochemistry and natural microbial ecology of the Floridan Aquifer and how they influence groundwater quality. It provides a baseline that can be used to enhance geochemical models that predict changes in groundwater quality following any type of recharge event.
"Characterization of native bacterial communities in aquifers is important because of the direct connection between some groundwater quality variables and bacterial activities. Groundwater bacteria catalyze geochemical reactions under conditions that can be significantly different within the same aquifer," said June Mirecki, a hydrogeologist with the U.S. Army Corps of Engineers. "Fundamental studies, like this study, have significant implications for truly understanding the fate of contaminants in aquifers targeted for aquifer storage, carbon sequestration and deep well injection."
The Floridan Aquifer flows southward at between 800-3,000 feet below the ground. It is among the most productive groundwater sources in the U.S. The upper zones of the Floridan aquifer are used as a drinking water source, while the lower zones, like those in this study, have been targeted for the recharge of treated surface water and reclaimed water and carbon sequestration repositories.
The fate of coliform bacteria injected into the lower zones of the Floridan Aquifer was studied as part of the Comprehensive Everglades Restoration Plan. The study was done in cooperation with the South Florida Water Management District and the U.S. Army Corps of Engineers.
The full report "Survival of Bacterial Indicators and the Functional Diversity of Native and Microbial Communities in the Floridan Aquifer, South Florida" by John T. Lisle is available online.
Ethan Alpern ( Phone: 703-648-4406 );
A recent USGS-led study shows new, recently-formed patches of permafrost in one of Alaska's retreating lakes, a finding that, at first glance, would seem at odds with prevailing theories about arctic climate.
Widespread lake shrinkage in discontinuous regions of permafrost has been linked to climate warming and shallow permafrost thaw. Counter-intuitively, USGS scientists have observed newly forming permafrost around Twelvemile Lake in interior Alaska, where lake water level has dropped by several meters over the past three decades.
"Central Alaskan lake shrinkage may be caused by shallow permafrost changes and not by increasing deep aquifer connections," said Martin A. Briggs, USGS, lead author of the study. "Newly formed permafrost along the shores of shrinking lakes may reduce groundwater outflow and allow them to refill."
Permafrost, or frozen ground lasting at least two consecutive years, typically forms in colder climates when average annual temperatures remain close to or below freezing. Permafrost soils accumulate ice and plant material and can impede groundwater flow. While the upper 1-2 meters may thaw seasonally, frozen soil and dead plant material continues to accumulate at depth over thousands of years, depending on the strength and duration of the colder climate.
During periods of thaw, water and gases are released from their frozen pockets of ice. By understanding permafrost thaw, its degradation in a warming climate, and its impacts on ecosystems and society, managers will be able to plan for rising global temperatures, and climate change. New permafrost formation should also be considered as a possibility in some systems.
This study considered ecological succession, the pattern of vegetation regrowth, within the receded lake margin as the driver of new permafrost through alterations in ground shading and water infiltration. This hypothesis was tested by modeling variably saturated groundwater flow and heat transport under freeze-thaw conditions.
The simulations supported new permafrost development under current climatic conditions, when the net changes effects of woody vegetation are considered, thus pointing to the role of ecological succession.
"Large lake level swings due to shallow permafrost thaw and subsequent refreezing due to ecological succession may be an important natural cycle," said Briggs. "However, in the long term, model simulations projected into the future to reflect even moderate climate warming indicate new permafrost around similar lake sites will stop forming and recede within seven decades, possibly ending the current natural cycle of lake level waning and waxing."
In summary, the findings in this study highlight the importance of vegetation succession in promoting permafrost regeneration in a lake system near the Arctic Circle, which is highly sensitive to subtle soil temperature changes.
This study was conducted by team of scientists from the U.S. Geological Survey and McGill University in Montreal, Canada, and was published in the journal of Geophysical Research Letters.
Scientists have successfully produced hybrid pups between a male western gray wolf and a female western coyote in captivity.
By artificially inseminating a female western coyote with western gray wolf sperm, U.S. Geological Survey scientists and partners from the St. Louis Zoo, University of California, Davis, and Wildlife Science Center recently demonstrated that coyotes are able to bear and nurture healthy hybrid offspring. The results contribute new information to an ongoing question about whether the eastern wolf of southeastern Canada (and formerly of the eastern U.S.) is a unique species that could be protected by the U. S. Endangered Species Act. The findings are published in the journal PLOS ONE.
"Our study adds one more piece to the ongoing controversy over whether the eastern wolf is a valid species," said David Mech, USGS scientist and the report's lead author.
During the 2012 and 2013 study, the scientists attempted to inseminate nine captive western coyotes with sperm from eight different gray wolves at the U.S. Department of Agriculture Wildlife Services National Wildlife Research Center Predator Research Facility in Logan, Utah. Three coyotes became pregnant, and one successfully birthed and nursed six live, healthy pups, currently housed at the Wildlife Science Center in Forest Lake, Minn., north of the Twin Cities.
Some geneticists have suggested recognizing the eastern wolf as a new species of wolf, and potentially adding it to the Endangered Species List. This proposal is based on mitochondrial DNA (mtDNA)—a type of DNA that can only be passed on to offspring by the mother—that has been found in wolves from Manitoba, Canada, through the Great Lakes into southeast Canada. Those wolves could have gotten their coyote-like mtDNA either from hybridization with coyotes or by hybridizing with the eastern wolf. The latter view is that of the geneticists who claim that the coyote-like mtDNA is from the eastern wolf, which is closely related to the coyote.
Scientists who propose that the coyote-like mtDNA came from female coyotes that bred with male, western wolves long ago believe that the eastern wolf is merely a smaller race of the wolf of the West.
The new USGS study shows that it is at least possible for western wolf sperm to fertilize western coyote eggs and that the mother coyote can bear and raise the hybrids.
"Our findings leave the eastern wolf debate open by adding further merit to the hybrid theory rather than disproving it," Mech said. "However, the findings are applicable to captive animals and are not necessarily true under natural conditions, so the counter-hybrid theory is not disproved either."
For more information on USGS wolf research, please visit the USGS Northern Prairie Wildlife Research Center website.
Nutrient enrichment of our nation's streams, lakes, and estuaries is widespread and can contribute to harmful algal blooms, increasing costs for drinking water and causing declines in ecosystem health.
Maps and tables describing the major sources and watershed inputs of nutrients to the Great Lakes and estuaries along the Atlantic coast, Gulf of Mexico, and the Pacific Northwest are now available online. These new maps and the data tables highlight the major sources of nutrients and the areas within a watershed that contribute the largest amounts of nutrients to 115 estuaries along the coastal areas and from 160 watersheds draining into the Great Lakes.
The data can serve further uses. For instance, water resource managers interested in a particular stream or estuary can use the online, interactive decision support tool to estimate how changes in nutrient inputs (source, type, and amount) affect nutrient loads at a downstream location.
A new reporting feature within the tool provides summary information on the amount and source of nutrients from upstream states or major hydrologic regions. For instance, output from the new tool shows the amount of nitrogen contributed from each of the 31 states that drain from the Mississippi River Basin into the Gulf of Mexico.
"This innovative combination of national maps and an online decision support tool provides unparalleled access to water-quality modeling information," said Jerad Bales, USGS acting associate director for Water. "It can be used to improve nutrient reduction strategies and inform nutrient policies across the nation."
These maps and data tables were produced using the USGS Spatially Referenced Regressions On Watershed attributes (SPARROW) nutrient models to explain spatial patterns in stream nutrient loads in relation to human nutrient inputs and natural processes and sources.
Successful management of our nation's waters requires an integrated approach that includes both monitoring and modeling to understand the affect, source type, input amounts, and performance of management activities on nutrients in local streams and ultimately in our Nation’s estuaries
Additional information on USGS nutrient monitoring and modeling activities by the National Water-Quality Assessment Program is available online.
Concentrations of polycyclic aromatic hydrocarbons (PAHs) in runoff from pavement with coal-tar-based sealcoat remain elevated for months following sealcoat application, according to a new study by the U.S. Geological Survey.
PAHs are an environmental health concern because they are toxic to fish and other aquatic life. A 2012 human health-risk analysis found that people living near pavement sealed with coal-tar-based products have an elevated risk of cancer.
USGS scientists evaluated concentrations of PAHs and azaarenes (chemicals similar in structure to PAHs but containing a nitrogen atom in the place of a carbon atom) in runoff from test plots sealed with either coal-tar-based or asphalt-based sealcoat starting five hours after sealcoat application and continuing for as long as three months after application. The full report, published in the journal Environmental Pollution, is available online.
Concentrations of PAHs and azaarenes in runoff from the coal-tar-sealcoated pavement were about 20 times higher than in runoff from the asphalt-sealcoated pavement, and about 40 times higher than in runoff from unsealed asphalt. Concentrations and assemblages of PAHs indicated that the asphalt-based sealcoat might have contained a small amount (5-10%) of coal-tar-based sealcoat.
Although the total concentration of PAHs varied relatively little over the three months following application, the concentration of high molecular weight (large) PAHs increased and the concentration of low molecular weight (small) PAHs decreased. The low molecular weight PAHs are acutely toxic to aquatic life, but the high molecular weight PAHs are more likely to cause mutations, birth defects, and cancer. The high molecular weight PAHs in the runoff were mostly in the form of particles.
This study is the first to investigate concentrations of azaarenes associated with sealcoat runoff. Sources of azaarenes include coal-tar and oil-shale processing, wood preserving, and chemical manufacturing. In samples of runoff collected just hours after sealcoat application, concentrations of the azaarene carbazole exceeded those of any other PAH or azaarene measured. Azaarenes have a large range of ecotoxicological effects, including acute toxicity, but have been less well studied than PAHs.
Sealcoat products are widely used in the United States, both commercially and by homeowners. The products are commonly applied to commercial parking lots (including strip malls, schools, churches and shopping centers), residential driveways, apartment complexes and playgrounds.
The USGS and the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) have teamed up to teach six online workshops open to public discussing Laser Specs for Field Hydrology and Biogeochemistry: Lessons Learned and Future Prospects.
The goal of this video workshop series is two-fold:
- To exchange technical information on application of laser spectrometry, both in field deployment and for analyzing field samples in the lab, and to compare performance with isotope-ratio mass spectrometry, the laboratory standard.
- To highlight research that makes use of this relatively recent and novel technology, both for understanding basic hydrologic processes, and as part of multi-tracer projects that allow new insights into hydrologic and geochemical systems.
Laser spectrometry enables new insights in environmental sciences for many problem-solving applications in hydrology, the science behind our understanding of water resources. Laser spectrometry enables measurements of the relative ratios of the stable isotopes of hydrogen and oxygen, found in all water, by determining absorption of water vapor of selected wavelengths of light reflected ten thousand times between mirrors in the spectrometer laser.
“With a commitment to both the advancement of water-quality science and education, this partnership with CUAHSI to promote these new breakthroughs in Laser Spectrometry is very exciting,” said Donna Myers, Chief of the USGS Office of Water Quality.
Participants are able to view the workshops live and participate by asking questions and posting comments on the discussion boards. By being a virtual workshop held online, national and international experts are able to provide their insights to participants on this new technology and its applications without traveling to a meeting. Each session of the series will be recorded and posted online after the event for those who cannot attend live or would like to watch them again.
"These visual workshops provide a no-cost, informative, and exciting opportunity for anyone interested to learn about hydrological science and technology from anywhere at their convenience," said Dr. Richard P. Hooper, Executive Director & President of CUAHSI, and former National Coordinator of the National Stream Quality Accounting Network (NASQAN) in the USGS Office of Water Quality from 1998-2003.
Education technology, specifically within higher education, is moving in the direction of Massive Open Online Courses (MOOCs), which is the newest innovation in distance learning, allowing students from all over the world to enroll in the courses.
This is the third such workshop jointly organized by USGS and CUAHSI, and the first to be held on-line. Past workshops have similarly focused on bringing new technologies to the forefront of water monitoring and research. CUAHSI is supported by a grant from the National Science Foundation.
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.