Sarah J. Kupferberg

• Ph.D.
• Senior Ecologist at Independent Scholar

Proliferations of Didymosphenia geminata are becoming prevalent in rivers around the globe. In the Sierra Nevada of California, Didymosphenia and other taxa that produce mucopolysaccharide stalks (e.g., Gomphoneis, Cymbella) can dominate benthic environments, particularly in the altered hydrologic and thermal regimes downstream of dams. We compared...

Freshwater biodiversity is imperiled across the globe, and multiple stressors such as habitat alteration, non-native species invasion, disease, and climate change can act in concert to threaten vulnerable taxa. The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis, is one of the causative factor...

Demographic models enhance understanding of drivers of population growth and inform conservation efforts to prevent population declines and extinction. For species with complex life histories, however, parameterizing demographic models is challenging because some life stages can be difficult to study directly. Integrated population models (IPMs) em...

Management of regulated rivers for yellow-legged frogs (Rana boylii) and salmonids exemplifies potential conflicts among species adapted to different parts of the natural flow and temperature regimes. Yellow-legged frogs oviposit in rivers in spring and depend on declining flows and warming temperatures for egg and tadpole survival and growth, wher...

Species with extensive geographical ranges pose special challenges to assessing drivers of wildlife disease, necessitating collaborative and large-scale analyses. The imperilled foothill yellow-legged frog (Rana boylii) inhabits a wide geographical range and variable conditions in rivers of California and Oregon (USA), and is considered threatened...

We report on the phenology of oviposition and metamorphosis by the threatened California Red-legged Frog (Rana draytonii) in the Sierra Nevada, California, USA, where few populations remain and efforts to establish new populations are underway. To understand the seasonality of oviposition and metamorph emergence of R. draytonii in the Sierra Nevada...

The decline in amphibian populations is one of the starkest examples of the biodiversity crisis. For stream breeding amphibians, alterations to natural flow regimes by dams, water diversions, and climate change have been implicated in declines and extirpations. Identifying drivers of amphibian declines requires long time series of abundance data be...

Chytridiomycosis, caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd), has contributed to amphibian declines globally, but drivers of outbreaks vary locally. Here we explore the role of drought in population and host-disease dynamics of the endangered stream-breeding foothill yellow-legged frog (Rana boylii). In central California (...

When unexpected predator-prey interactions are observed, abiotic conditions can reveal insights about the ecology of the species involved. During one of the warmest months of May in the last 30 y (2008), we observed an adult Northwestern Pond Turtle, Actinemys marmorata, preying upon a paedomorphic Coastal Giant Salamander, Dicamptodon tenebrosus,...

Amphibian diversity has declined due to the infectious disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Coexistence between amphibian hosts and this pathogen in some locations is attributed to the presence of the cutaneous bacterium Janthinobacterium lividum (Jliv). This microbe inhibits the growth of Bd...

• Rivers around the world are undergoing shifts in thermal regime due to climate change and human appropriation of water resources. The local impacts of thermal regime change are challenging to predict because water temperature can influence aquatic organisms and communities at multiple levels simultaneously. For example, thermal change can influen...

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 (Ran...

In Search of Lost Frogs: The Campaign to Rediscover the World’s Rarest Amphibians. R. Moore. 2014. Firefly Books. ISBN 9781770854642. 256 p. $35.00 (hardcover).—There was a time in the not too distant past when being fond of amphibians was considered a comical eccentricity rather than a tragic emblem of environmental concern. In the 1930s, popular...

Letter Report to California State Parks regarding the efforts to protect Rana boylii in advance of a dam removal project

The fungal pathogen Batrachochytrium dendrobatidis (Bd) has been identified as the primary factor in many amphibian declines around the world, yet its effect on lowland populations of California anurans, such as the foothill yellow-legged frog (Rana boylii) is poorly understood. R. boylii has declined from more than half of its former range, but ha...

In response to a USFWS request for information regarding Rana boylii, we compiled data for this riverine frog which has disappeared from more than half its range. Because R. boylii females lay a discrete and readily countable clutch of eggs, a standard practice among researchers, agencies, and utility companies is to assess abundance by making annu...

This long-anticipated reference and sourcebook for California’s remarkable ecological abundance provides an integrated assessment of each major ecosystem type—its distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans...

The ranges and abundances of species that depend on freshwater habitats are declining worldwide. Efforts to counteract those trends are often hampered by a lack of information about species distribution and conservation status and are often strongly biased toward a few well-studied groups. We identified the 3,906 vascular plants, macroinvertebrates...

Differences in animal assemblages between an existing California State Park, the Carnegie State Vehicular Recreation Area, and a proposed Expansion Area can be used to predict impacts to biological resources from Off Highway Vehicular (OHV) recreation because the two properties share similar topography, elevations, soils, and habitat types but diff...

The liberalization of marijuana policies, including the legalization of medical and recreational marijuana, is sweeping the United States and other countries. Marijuana cultivation can have significant negative collateral effects on the environment that are often unknown or overlooked. Focusing on the state of California, where by some estimates 60...

In the fall of 2013 we observed dead and dying juvenile foothill yellow-legged frogs (Rana boylii) in the Bay Area's Alameda Creek, a location where annual amphibian breeding censuses have been conducted since 2003. We attribute the die-off to an outbreak of chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), in whi...

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 pe...

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...

The decline of the river breeding foothill yellow-legged frog (Rana boylii) has been attributed to the altered flow regimes and habitat fragmentation associated with water storage and hydropower dams. Recent research has provided insight into potential mechanisms for these declines, confirming that early life history stages (embryos and tadpoles) a...

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 sco...

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...

Background/Question/Methods Natural hydrologic regimes are fundamental properties of fluvial systems, shaping geomorphology, physical and chemical gradients, species compositions, and the ecology of riverine communities. Hydrologic alterations due to channelization, regulation by dams, and watershed development are among the most ubiquitous anthro...

Background/Question/Methods When utilities re-license their hydro-electric projects with the Federal Energy and Regulatory Commission, the implications of various flow proposals to downstream thermal conditions are evaluated. Dam operations can either raise or lower water temperatures compared to free-flowing conditions. Retention of water can res...

1. This study examined how interactions between resources that vary in edibility, and herbivores that vary in ability to acquire resources, control primary productivity. In a northern California river, grazing on Cladophora glomerata, a relatively inedible filamentous green alga, and its more nutritious epiphytic diatoms, was manipulated by exposin...

This chapter discusses the development and evolution of feeding mechanisms in aquatic larval vertebrates, such as fishes and amphibians. Fish larva is the immature life-history stage that differs morphologically from the juvenile and adult. The time between hatching and metamorphosis may range from a few days in tropical fish species, to a few week...

To quantify the impact of garter snakes (Thamnophis hydrophilus, formerly T. couchii) on tadpole prey (Hyla regilla), I experimentally examined whether: (1) garter snakes have greater impact on tadpole numbers or on behavior; (2) tadpole patch choice follows the rule of minimizing the ratio of mortality risk, μ, to foraging gain, g; and (3) predato...

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...

SYNOPSIS. Focus on tadpole diet and foraging behavior offers potential for integrating ecological and endocrinological approaches to understanding anuran metamorphosis. Natural larval diets vary widely in relative amounts of protein, carbohydrate and lipid, factors known to influence thyroid hormone function, which in turn is essential for metamorp...

SYNOPSIS. Focus on tadpole diet and foraging behavior offers potential for integrating ecological and endocrinological approaches to understanding anuran metamorphosis. Natural larval diets vary widely in relative amounts of protein, carbohydrate and lipid, factors known to influence thyroid hormone function, which in turn is essential for metamorp...

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,...

The quality of algae as food for larval Pacific treefrogs, Hyla regilla, varies among algal taxa. Tadpole diets were manipulated in enclosures in the South Fork Eel River, northern California. Enclosed tadpoles were fed ad libitum one of the dominant filamentous green algae (Cladophora, Zygnema, Mougeotia, or Oedogonium), the dominant cyanobacteriu...

The ability of an exotic species to invade and establish in a new community is determined in part by its competitive status relative to native species (Brown 1989), and in part by its vulnerability to local predators. Bullfrogs (Rana catesbeiana) are currently invading the South Fork of the Eel River in northem Califomia. Along reaches where they a...

Thesis (Ph. D. in Integrative Biology)--University of California, Berkeley, May 1996. Includes bibliographical references (leaf 286).