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.


Hydrologic Investigations
USGS Toxics Substances Hydrology program

Pesticide lab.
K. Jones (USGS) extracting a water sample for pesticide analysis at Pesticide Fate Research Laboratory. Photo by: R. Todd.

Water - ARMI Papers & Reports

Papers & Reports Survival estimates for the invasive American Bullfrog
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Authors: Howell PE, Muths E, Sigafus BH, Hossack BR | Outlet: Amphibia-Reptilia
We used five years of capture mark-recapture data to estimate annual apparent survival of post-metamorphic bullfrogs in a population on the Buenos Aires National Wildlife Refuge in their invaded range in Arizona, U.S.A.
Study area in southern Arizona (USA) showing water endmember location (Parker Canyon Lake; bottom right) and examples of three waterbodies with different sizes and spectral characteristics using June 2007 Landsat 5 TM (left) and September 2018 Landsat 8 OLI (right).
Study area in southern Arizona (USA) showing water endmember location (Parker Canyon Lake; bottom right) and examples of three waterbodies with different sizes and spectral characteristics using June 2007 Landsat 5 TM (left) and September 2018 Landsat 8 OLI (right).
Papers & Reports Estimating inundation of small waterbodies with sub-pixel analysis of Landsat imagery: long-term trends in surface water area and evaluation of common drought indices
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Authors: Sall I, Jarchow CJ, Sigafus BH, Eby LA, Forzley MJ, Hossack BH | Outlet: Remote Sensing in Ecology and Conservation
Small waterbodies are numerically dominant in many landscapes and provide several important ecosystem services, but automated measurement of waterbodies smaller than a standard Landsat pixel (0.09 ha) remains challenging. To further evaluate sub-Landsat pixel techniques for estimating inundation extent of small waterbodies (basin area: 0.061.79 ha), we used a partial spectral unmixing method with matched filtering applied to September 1985–2018 Landsat 5 and 8 imagery from southern Arizona, USA. We estimated trends in modeled surface water area each September and evaluated the ability of several common drought indices to explain variation in mean water area. Our methods accurately classified waterbodies as dry or inundated (Landsat 5: 91.3%; Landsat 8: 98.9%) and modeled and digitized surface water areas were strongly correlated (R2 = 0.700.92; bias = -0.024 – -0.015 ha). Estimated surface water area was best explained by the 3-month seasonal standardized precipitation index (SPI03; July?September) and. We found a wide range of estimated relationships between drought indices (e.g., SPI vs. Palmer Drought Severity Index) and estimated water area, even for different durations of the same drought index (e. g., SPI01 vs SPI12). Mean surface area of waterbodies decreased by ~14% from September 1985 to September 2018, which matched declines in annual precipitation in the area and is consistent with broader trends of reduced inundation extent based on larger waterbodies. Estimated of surface water area and trends over time were also consistent when we limited analyses to waterbodies ? 0.04 ha or those that varied most in size (based on CV). These results emphasize the importance of understanding local systems when relying on drought indices to infer variation in past or future surface water dynamics. Several challenges remain before widespread application of sub-pixel methods is feasible, but our results provide further evidence that partial spectral unmixing with matched filtering provides reliable measures of inundation extent of small waterbodies.

Papers & Reports Species-specific responses to wetland mitigation among amphibians in the Greater Yellowstone Ecosystem
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Authors: Swartz LK, Lowe WH, Muths E, Hossack BR | Date: 2020 | Outlet: Restoration Ecology 28:206-214
Habitat loss and degradation are leading causes of biodiversity declines, therefore assessing the capacity of created mitigation wetlands to replace habitat for wildlife has become a management priority. We used single season occupancy models to compare occurrence of larvae of four species of pond-breeding amphibians in wetlands created for mitigation, wetlands impacted by road construction, and unimpacted reference wetlands along a highway corridor in the Greater Yellowstone Ecosystem, U.S.A. Created wetlands were shallow and had less aquatic vegetation and surface area than impacted and reference wetlands. Occupancy of barred tiger salamander (Ambystoma mavortium) and boreal chorus frog (Pseudacris maculata) larvae was similar across wetland types, whereas boreal toads (Anaxyrus boreas) occurred more often in created wetlands than reference and impacted wetlands. However, the majority of created wetlands (> 80%) dried partially or completely before amphibian metamorphosis occurred in both years of our study, resulting in heavy mortality of larvae and, we suspect, little to no recruitment. Columbia spotted frogs (Rana luteiventris), which require emergent vegetation that is not common in newly-created wetlands, occurred commonly in impacted and reference wetlands but were found in only one created wetland. Our results show that shallow created wetlands with little aquatic vegetation may be attractive breeding areas for some amphibians, but may result in high mortality and little recruitment if they fail to hold water for the entire larval period.
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