@article{Catenazzi2017,
title = {Variation in thermal niche of a declining river-breeding frog:From counter-gradient responses to population distributionpatterns},
author = {Alessandro Catenazzi, Sarah J. Kupferberg},
doi = {https://doi.org/10.1111/fwb.12942 },
year = {2017},
date = {2017-03-28},
journal = {Freshwater Biology},
volume = {62},
number = {7},
pages = {1255-1265},
abstract = {When dams or climate change alter the thermal regimes of rivers, conditions can shift outside optimal ranges for aquatic poikilothermic vertebrates. Plasticity in thermal performance and preference, however, may allow temperature‐vulnerable fauna to persist under challenging conditions.
To determine the effects of thermal regime on Rana boylii (Ranidae), a threatened frog species endemic to rivers of California and Oregon, we quantified tadpole thermal preferences and performance in relation to thermal conditions. We monitored temperature and censused populations across a coastal to inland cline in six catchments where dams have altered thermal environments in close proximity to river reaches with natural conditions.
We found geographic variation in population distribution and abundance based on river size combined with water temperature. The large inland rivers that supported breeding frogs, although cooler in spring due to snowmelt, became warmer during the summer than occupied coastal sites. Inland populations were constrained to reaches where the average temperature over the warmest 30 days ranged from 17.6 to 24.2°C, higher than coastal rainfall‐driven systems where averages ranged from 15.7 to 22.0°C. Frogs in rivers with hypolimnetic‐release dams bred in colder waters than they did in free‐flowing rivers.
Common‐garden and field translocation experiments revealed local adaptations in larval growth and phenotypically plastic thermoregulatory behaviour. Tadpoles from all rivers had a positive linear growth response to temperature, but individuals from inland rivers displayed intrinsically higher growth rates. Consistent with a counter‐gradient model of selection in which the response to temperature change is in the opposite direction of the change, individuals from cooler rivers selected warmer temperatures. When reared under common conditions, however, tadpoles showed similar temperature preferences regardless of source river.
Our results suggest a role for local growth rate adaptation in structuring the distribution of Rana boylii. Plastic thermoregulatory behaviour by tadpoles may explain how small populations are able to persist where dams release cold water. Management of edgewater habitats to increase the availability of warm micro‐sites may ameliorate this impact.},
keywords = {climate sensitivity, common-garden experiment, declining amphibians, hypolimnetic releases, Rana boylii},
pubstate = {published},
tppubtype = {article}
}

@article{Lind2016,
title = {Foothill yellow-legged frog (Rana boylii) oviposition site choice at multiple spatial scales},
author = {Amy Lind and Hartwell Welsh and Clara Wheeler},
doi = {https://doi.org/10.1670/14-169},
year = {2016},
date = {2016-06-01},
journal = {Journal of Herpetology},
volume = {50},
number = {2},
pages = {263-270},
abstract = {Studies of resource selection at multiple scales are critical to understanding ecological and evolutionary attributes of a species. We analyzed relative abundance, habitat use, and oviposition site selection of Foothill Yellow-Legged Frogs (Rana boylii) at 11 localities across two geographic regions in California (northern Coast Range and Sierra Nevada) over 16 yr. We found narrow ranges for oviposition microhabitat characteristics (water depth, water velocity, and stream substrate) among study localities. At the Main and South forks of the Trinity River, variances of the habitat traits were lower for oviposition microsites than for random points within breeding areas, indicating fine-scale selection. On the South Fork Trinity, egg mass relative abundances were negatively associated with water depth and positively associated with distance from the shoreline, suggesting that breeding areas with high egg mass relative abundances generally occurred in wide shallow areas. We observed long-term repeated use of breeding sites. At the South Fork Trinity, 63% of potentially suitable breeding areas were used consecutively for 3 yr, and at Hurdygurdy Creek several areas were used in ≥11 yr. Oviposition site selection and microhabitat specificity may result in population stability even within the substantial temporal and spatial variability of stream environments. Management of stream environments and conservation plans for R. boylii could benefit by preserving hydrologic processes that produce these specific habitats and identifying and protecting high-use breeding areas.
},
keywords = {Rana boylii},
pubstate = {published},
tppubtype = {article}
}

@article{Kupferberg2012,
title = {Effects of Flow Regimes Altered by Dams on Survival, Population Declines, and Range-Wide Losses of California River-Breeding Frogs},
author = {Sarah J. Kupferberg and Wendy J. Palen and Amy J. Lind and Steve Bobzien and Alessandro Catenazzi and Joe Drennan and Mary E. Power},
url = {https://angelo.berkeley.edu/wp-content/uploads/Kupferberg_Flowregdamsfrogs_ConsBio2012.pdf
https://angelo.berkeley.edu/wp-content/uploads/Kupferberg_SupMat_ConsBio2012.pdf},
doi = {10.1111/j.1523-1739.2012.01837.x},
year = {2012},
date = {2012-05-17},
journal = {Conservation Biology},
volume = {26},
number = {3},
pages = {513-524},
abstract = {Widespread alteration of natural hydrologic patterns by large dams combined with peak demands for power and water delivery during summer months have resulted in frequent aseasonal flow pulses in rivers of western North America. Native species in these ecosystems have evolved with predictable annual flood- drought cycles; thus, their likelihood of persistence may decrease in response to disruption of the seasonal synchrony between stable low-flow conditions and reproduction. We evaluated whether altered flow regimes affected 2 native frogs in California and Oregon (U.S.A.) at 4 spatial and temporal extents. We examined changes in species distribution over approximately 50 years, current population density in 11 regulated and 16 unregulated rivers, temporal trends in abundance among populations occupying rivers with different hydrologic histories, and within-year patterns of survival relative to seasonal hydrology. The foothill yellow- legged frog (Rana boylii), which breeds only in flowing water, is more likely to be absent downstream of large dams than in free-flowing rivers, and breeding populations are on average 5 times smaller in regulated rivers than in unregulated rivers. Time series data (range = 8 − 19 years) from 5 populations of yellow- legged frogs and 2 populations of California red-legged frogs (R. draytonii) across a gradient of natural to highly artificial timing and magnitude of flooding indicate that variability of flows in spring and summer is strongly correlated with high mortality of early life stages and subsequent decreases in densities of adult females. Flow management that better mimics natural flow timing is likely to promote persistence of these species and others with similar phenology.
},
keywords = {amphibian declines, hydropower, Rana boylii, Rana draytonii},
pubstate = {published},
tppubtype = {article}
}

@article{Kupferberg2011,
title = {Water velocity tolerance in tadpoles of the foothill yellow-legged frog (Rana boylii): swimming performance, growth, and survival},
author = {Sarah J. Kupferberg and Amy J. Lind and Vanessa Thill and Sarah M. Yarnell},
url = {https://angelo.berkeley.edu/wp-content/uploads/Kupferberg_2011_Copeia.pdf},
doi = {10.1643/CH-10-035},
issn = {0045-8511},
year = {2011},
date = {2011-03-01},
journal = {Copeia},
volume = {2011},
number = {1},
pages = {141-152},
abstract = {We explored the effects of large magnitude flow fluctuations in rivers with dams, commonly referred to as pulsed flows, on tadpoles of the lotic-breeding Foothill Yellow-legged Frog, Rana boylii. We quantified the velocity conditions in habitats occupied by tadpoles and then conducted experiments to assess the tolerance to values at the upper limit of, and outside, the natural range. In laboratory flumes and field enclosures we mimicked the velocities observed during pulsed flows. In all experimental venues, the behavioral response of tadpoles was to seek refuge in the channel substrate when velocity increased. In a large laboratory flume, tadpoles moved freely at low water velocities (0–2 cm•s−1) and then sheltered among rocks when velocity increased. In a smaller scale laboratory flume, the median critical velocity was 20.1 cm•s−1. Critical velocity varied inversely with tadpole size, developmental stage, and proportion of time spent swimming. Velocities as low as 10 cm•s−1 caused tadpoles approaching metamorphosis to be displaced. In field mesocosm experiments, tadpoles exposed to repeated sub-critical velocity stress (5–10 cm•s−1) grew significantly less and experienced greater predation than tadpoles reared at ambient velocities. Responses to velocity manipulations were consistent among tadpoles from geographically distinct populations representing the three identified clades within R. boylii. The velocities associated with negative effects in these trials are less than typical velocity increases in near shore habitats when recreational flows for white water boating or peaking releases for hydroelectric power generation occur.
},
keywords = {Rana boylii, tadpoles, water velocity},
pubstate = {published},
tppubtype = {article}
}

@article{Kupferberg2009b,
title = {Parasitic copepod (Lernea cyprinacea) outbreaks in foothill yellow-legged frogs (Rana boylii) linked to unusually warm summers and amphibian malformations in northern California},
author = {Sarah J. Kupferberg and Alessandro Catenazzi and Kevin Lunde and Amy J. Lind and Wendy J. Palen
},
url = {https://angelo.berkeley.edu/wp-content/uploads/Kupferberg_2009_Cop.pdf},
doi = {10.1643/CH-08-011},
year = {2009},
date = {2009-09-01},
journal = {Copeia},
volume = {2009},
number = {3},
pages = {529-537},
abstract = {How climate change may affect parasite–host assemblages and emerging infectious diseases is an important question in amphibian decline research. We present data supporting a link between periods of unusually warm summer water temperatures during 2006 and 2008 in a northern California river, outbreaks of the parasitic copepod Lernaea cyprinacea, and malformations in tadpoles and young of the year Foothill Yellow-legged Frogs (Rana boylii). Relative to baseline data gathered since 1989, both 2006 and 2008 had significantly longer periods when daily mean water temperatures exceeded 20°C compared to years without copepod outbreaks. Infestation varied spatially in the watershed, as prevalence increased concomitantly with temperature along a 5.2 km longitudinal transect. At breeding sites of R. boylii with copepods in 2006, infestation ranged from 2.9% of individuals upstream to 58.3% downstream. In 2008, copepods were absent from the most upstream sites and infested up to 28.6% of individuals sampled at downstream locations. Copepods most frequently embedded near a hind limb or the cloaca. Among individuals with parasites in 2006, 26.5% had morphological abnormalities compared to 1.1% of un-infested individuals. In 2008 when the infestation peak occurred late in development (post Gosner stage 39), abnormalities were not associated with copepod infestation. In both years, recently metamorphosed frogs with copepods were, on average, slightly smaller than those not infested. These occurrences represent a sudden increase in local prevalence atypical for this river ecosystem. Previously we had only once seen copepods on amphibians (on non-native Bullfrogs, Rana catesbeiana), six km further downstream. Pacific Chorus Frogs, Pseudacris regilla, which co-occur with R. boylii in shallow near shore habitats were not used as hosts. The data suggest that increasing summer water temperatures, decreased daily discharge, or a combination of both, promote outbreaks of this non-native parasite on an indigenous host, and could present a threat to the long-term conservation of R. boylii under the flow regime scenarios predicted by climate change models.},
keywords = {amphibina malformations, Parasitic copecod, Rana boylii, warm summer},
pubstate = {published},
tppubtype = {article}
}

@article{Kupferberg2009,
title = {Pulsed flow effects on the Foothill Yellow‐ Legged Frog (Rana boylii): Integration of empirical, experimental, and hydrodynamic modeling approaches (Final Report)},
author = {Sarah Kupferberg and A. Lind and S. Yarnell and J. Mount},
url = {https://angelo.berkeley.edu/wp-content/uploads/Kupferberg_2009_CEC.pdf},
doi = {CEC‐500‐2009‐002},
year = {2009},
date = {2009-08-01},
journal = {Public Interest Energy Research Program: Final Project Report},
abstract = {Four analytical approaches support the hypothesis that altered flow regimes, particularly spring and summer pulsed discharges, contribute to the decline of foothill yellow‐legged frogs (Rana boylii) in regulated rivers. (1) A review of literature and FERC re‐licensing reports indicates that egg masses are negatively affected by pulsed flows via scouring, or desiccation, if spawning occurs during spills that abruptly cease. Tadpole stranding was documented in several studies. Effects on young of the year and older life stages were equivocal. (2) Long‐term population monitoring in three watersheds shows that frequency and magnitude of pulsed flows that harm embryos and tadpoles are factors in determining adult population status. These effects are offset by 2‐3 years, representing the time to reproductive maturity in central and northern California. (3) Experiments illustrate that tadpoles seek refuge in the substrate as velocity increases, are not adapted for sustained swimming, and are swept downstream. Tadpoles confined to refugia face predation and energetic costs in terms of growth and development. (4) Simulations using River2D, a 2‐dimensional hydrodynamic model, show that velocity and depth conditions exceed tolerances of R. boylii egg masses and tadpoles during a range of pulsed flows. While meso‐scale suitability of near shore habitat was accurately predicted, error in modeled point velocities at egg locations arose from limitations in fine scale surveying of the large, poorly sorted, rock substrate. Management that avoids aseasonal flow fluctuations would benefit R. boylii, and other taxa, whose lifecycles are synchronous with the natural timing of runoff in Californiaʹs rivers.},
note = {This is the final report. There is alternatively a progress report available.},
keywords = {2D hydraulic modeling, amphibian populations, Cladophora glomerata, FERC relicensing, pulse flow effects, Rana boylii, river regulation, tadpole swimming},
pubstate = {published},
tppubtype = {article}
}

@article{Kupferberg1997,
title = {Bullfrog (Rana catesbeiana) invasion of a California river: the role of larval competition},
author = {Sarah J. Kupferberg},
url = {https://angelo.berkeley.edu/wp-content/uploads/Kupferberg_Ecology1997.pdf},
issn = {0012-9658},
year = {1997},
date = {1997-09-00},
journal = {Ecology},
volume = {78},
number = {6},
pages = {1736-1751},
abstract = {I studied the invasion of Rana catesbeiana (the bullfrog) into a northern California river system where bullfrogs are not native. Native yellow-legged frogs, Rana boylii, a species of special concern, were almost an order of magnitude less abundant in reaches where bullfrogs were well established. I assessed the potential role of larval competition in contributing to this displacement in a series of field manipulations of tadpole density and species composition. The impact of R. catesbeiana on native tadpoles in the natural community agreed with the outcome of more artificial experiments testing pairwise and three-way interactions. In 2-m(2) enclosures with ambient densities of tadpoles and natural river biota, bullfrog tadpoles caused a 48% reduction in survivorship of R. boylii, and a 24% decline in mass at metamorphosis. Bullfrog larvae had smaller impacts on Pacific treefrogs, Hyla regilla, causing 16% reduction in metamorph size, and no significant effect on survivorship. Bullfrog tadpoles significantly affected benthic algae, although effects varied across sites. Responses to bullfrogs in field settings were similar qualitatively to results seen in smaller-scale experiments designed to study size-structured competition among disparate age/size classes of species pairs and trios. Competition from large overwintering bullfrog larvae significantly decreased survivorship and growth of native tadpoles. Competition from recently hatched bullfrog larvae also decreased survivorship of R. boylii and H. regilla. Native species competed weakly, both interspecifically and intraspecifically. The only suggestion of a negative impact of a native species on bullfrogs was a weak effect of H. regilla on recent hatchlings. Competition appeared to be mediated by algal resources, and there was no evidence for behavioral or chemical interference. These results indicate that, through larval interactions, bullfrogs can exert differential effects on native frogs and perturb aquatic community structure.},
keywords = {algae, biological invasions, California, grazing, Hyla regilla, Rana boylii, Rana catesbeiana, rivers, size-structured competition},
pubstate = {published},
tppubtype = {article}
}

@article{Kupferberg1996,
title = {Hydrologic and geomorphic factors affecting conservation of a river-breeding frog (Rana boylii)},
author = {Sarah J. Kupferberg},
url = {https://angelo.berkeley.edu/wp-content/uploads/Kupferberg_EcolApp1996.pdf},
doi = {http://dx.doi.org/10.2307/2269611},
year = {1996},
date = {1996-11-00},
journal = {Ecological Applications},
volume = {6},
number = {4},
pages = {1332-1344},
abstract = {Organisms that live in highly variable environments, such as rivers, rely on adaptations to withstand and recover from disturbance. These adaptations include behavioral traits, such as habitat preference and plasticity of reproductive timing, that minimize the effects of discharge fluctuation. Studies linking hydrologic regime, habitat preference, and population processes, however, are predominantly limited to fish. Information on other sensitive taxa is necessary to facilitate conservation of multispecies assemblages and restoration of biodiversity in degraded river channels. I studied the functional relationship between physical habitat and reproduction of the foothills yellow-legged frog (Rana boylii), a California State Species of Special Concern. From 1992 to 1994, I mapped breeding sites along 5.3 km of the South Fork Eel River in northern California and monitored egg survival to hatching. Frogs selected sites over a range of spatial scales and timed their egg-laying to avoid fluctuations in river stage and current velocity associated with changes in discharge. The main sources of mortality were desiccation and subsequent predation of eggs in a dry year and scour from substrate in wet years, both caused by changes in stage and velocity. At the finest spatial scale, frogs attached eggs to cobbles and boulders at lower than ambient flow velocities. At larger scales, breeding sites were near confluences of tributary drainages and were located in wide, shallow reaches. Clutches laid in relatively narrower and deeper channels had poor survival in rainy as well as dry springs. Most breeding sites were used repeatedly, despite between- and within-year variation in spring stage of the river. This pattern of site selection suggests that conservation of Rana boylii may be enhanced by maintaining or restoring channels with shapes that provide stable habitat over a range of river stages.},
keywords = {amphibians, Anura, frogs, geomorphology, hydrology, oviposition, physical habitat, Rana boylii, reproductive success, river, spatial scale},
pubstate = {published},
tppubtype = {article}
}