K. Jones (USGS) extracting a water sample for pesticide analysis at Pesticide Fate Research Laboratory. Photo by: R. Todd.
The collaborative design which joins wildlife biologists and hydrologists enables ARMI to ask the kinds of questions it does about the environmental variables that affect amphibians in a truly integrated manner. Understanding how water quality, quantity, or timing affects amphibians is a critical component of ARMI research.
A hydrologist is associated with each ARMI region and works with the ARMI PI to develop and implement research and monitoring projects. These collaborations enable ARMI to ask questions about how water quality (e.g., nutrients, agro-chemicals, acidification), water budgets (e.g., ground and surface water models), storm surge impacts, or other hydrologic conditions can affect amphibian life cycles, disease transport, or habitat quality.
USGS Toxics Substances Hydrology program
ARMI Products on Water
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Restored agricultural wetlands in central Iowa: habitat quality and amphibian response
Authors: Reeves RA, Pierce CL, Smalling KL, Klaver RW, Vandever MW, Battaglin WA, Muths E | Date: 2016-02 | Outlet: Wetlands | Format: .PDF
Amphibians are declining throughout the United States and worldwide due, partly, to habitat loss. The Iowa Conservation Reserve Enhancement Program (CREP) strategically restores wetlands to denitrify tile drainage effluent and restore ecosystem services. Understanding how eutrophication , hydroperiod, predation, and disease affect amphibians in restored wetlands is central to maintaining healthy amphibian populations in the region. We examined the quality of amphibian habitat in restored CREP wetlands relative to reference wetlands by comparing species richness, developmental stress, and adult leopard frog (Lithobates pipiens) survival probabilities to a suite of environmental metrics. Although measured habitat variables differed between restored and reference wetlands, differences appeared to have sub-lethal rather than lethal effects on resident populations . There were few differences in amphibian species richness and no difference in estimated survival probabilities between wetland types. Restored wetlands had more nitrate and alkaline pH, longer hydroperiods, and were deeper, whereas reference wetlands had more amphibian chytrid fungus zoospores and resident amphibians exhibited increased developmental stress. Restored and reference wetlands are both important components of the landscape in central Iowa and maintaining a complex of fish-free wetlands with a variety of hydroperiods will likely contribute to the persistence of amphibians in this landscape.
Geographically Isolated Wetlands:
Authors: Mushet DM, Calhoun AJK, Alexander LC, Cohen MJ, DeKeyser ES, Fowler L, Lane CR, Lang MW, Rains MC, Walls SC
We explore the category geographically isolated
wetlands(GIWs; i.e., wetlands completely surrounded by
uplands at the local scale) as used in the wetland sciences.
As currently used, the GIW category (1) hampers scientific
efforts by obscuring important hydrological and ecological
differences among multiple wetland functional types, (2)
aggregates wetlands in a manner not reflective of regulatory
and management information needs, (3) implies wetlands so
described are in some way isolated, an often incorrect
implication, (4) is inconsistent with more broadly used and
accepted concepts of geographic isolation, and (5) has
injected unnecessary confusion into scientific investigations
and discussions. Instead, we suggest other wetland classification
systems offer more informative alternatives. For
example, hydrogeomorphic (HGM) classes based on wellestablished
scientific definitions account for wetland functional
diversity thereby facilitating explorations into
questions of connectivity without an a priori designation of
isolation. Additionally, an HGM-type approach could be
used in combination with terms reflective of current regulatory
or policymaking needs. For those rare cases in which
the condition of being surrounded by uplands is the relevant
distinguishing characteristic, use of terminology that does
not unnecessarily imply isolation (e.g., upland embedded
wetlands) would help alleviate much confusion caused by
the geographically isolated wetlands misonomer.
The Source, Discharge, and Chemical Characteristics of Selected Springs, and the Abundance and Health of Associated Endemic Anuran Species in the Mojave Network of Parks
Authors: Martin P, Schroeder R, Smith G, Flint A, Gallegos E, Fisher R | Date: 2015-05-08 | Outlet: USGS Scientific Investigations Report 2015-5027 | Format: .PDF
Hydrological and biological investigations were done during 2005 and 2006 in cooperation with the U.S. National Park Service to investigate the source, discharge, and chemical characteristics of selected springs and the abundance and health of endemic anuran (frog and toad) species at Darwin Falls in Death Valley National Park, Piute Spring in Mojave National Preserve, and Fortynine Palms Oasis in Joshua Tree National Park. Discharge from the springs at these sites sustains isolated riparian habitats in the normally dry Mojave Desert. Data were collected on water quantity (discharge) and quality, air and water temperature, and abundance and health of endemic anuran species. In addition, a single survey of the abundance and health of endemic anuran species was completed at Rattlesnake Canyon in Joshua Tree National Park. Results from this study were compared to limited historical data, where they exist, and can provide a baseline for future hydrological and biological investigations to evaluate the health and sustainability of the resource and its response to changing climate and increasing human use.
Radiocarbon dating of the water yielded estimated ages of about 7,000 years at Piute Spring and about 3,000 years at Darwin Spring, and tritium-helium-3 dating indicated an age of less than 2 years at Fortynine Palms Oasis. Stable hydrogen-isotope ratios were used to interpret an average altitude of recharge of 2,348 meters for Darwin Spring (about 1,415 meters higher than the altitude of Darwin Spring), 1,668 meters for Piute Spring (about 766 meters higher than the altitude of Piute Spring), and 1,400 meters for the Upper Pool at Fortynine Palms Oasis (about 543 meters higher than the altitude of the Upper Pool). Water-quality data collected for this study did not appear to be sensitive to trends in precipitation or seasonality in the Darwin Falls and Piute Spring study areas; however, it was sensitive to trends in Fortynine Palms Oasis where salinity increased by more than 10 percent during the 2 years of this study. Such a rapid response is consistent with the comparatively short travel time of less than 2 years from recharge to discharge at Fortynine Palms Oasis. Of the 14 trace elements analyzed, only concentrations of uranium at Fortynine Palms Oasis and arsenic at Darwin Spring were above drinking water standards; both constituents are derived from natural sources in the drainage basin and, therefore, are likely to have accumulated as a result of natural processes.
Endemic anuran species were surveyed at Darwin Falls for the western toad [Anaxyrus boreas] and the red-spotted toad [Anaxyrus punctatus], at Piute Spring for the red-spotted toad, and at Fortynine Palms Oasis for the red-spotted toad and California treefrog [Pseudacris cadaverina]. Historically, red-spotted toads were at the edge of their range at Darwin Falls, but they were not detected during this study and have not been detected since the early 1980s. The 2006 western toad population at Darwin Falls was estimated at 381 adults (95-percent confidence interval [CI] of 314–482). The population of red-spotted toads at Piute Spring was estimated at 1,153 adults (95-percent CI of 935–1,503). However, an elevated rate of abnormalities (approximately 5 percent) was recorded in red-spotted toads as well as the presence of the chytrid fungus,[Bactrochochytrium dendrobatidis], at Piute Spring. In Joshua Tree National Park, the California treefrog now occupies only three of the seven historically occupied drainages. Populations of California treefrogs at Fortynine Palms Oasis have declined more than 50 percent from 288 in 1969–71 to 109 in 2006. A similar decline was observed in the populations of red-spotted toads at Fortynine Palms Oasis from 300 adults in 1969–71 to 155 adults (95-percent CI of 90–139) in 2006. The red-spotted toads at Fortynine Palms Oasis also exhibited the presence of [Bactrochochytrium dendrobatidis].