Productivity and significance of headwater streams: population structure and biomass of the black-bellied salamander (Desmognathus quadramaculatus)

1. Headwater streams are a significant feature of the southern Appalachian landscape, comprising more than 70% of the total stream length in the region. Salamanders are the dominant vertebrate within headwater‐riparian forest ecosystems, but their ecological role is not clearly understood. 2. We studied a population of black‐bellied salamanders (Desmognathus quadramaculatus) at a headwater stream in the southern Appalachian Mountains using radio‐telemetry and mark‐recapture methods. The length and area of headwater streams in the region were estimated using GIS. 3. Home ranges of radio‐tracked salamanders were relatively small (mean = 1.06 m²). Adult salamanders in our telemetry study inhabited edge microhabitats significantly more often than either stream or riparian microhabitats, and the same trend was observed in the mark‐recapture study. 4. We estimated the population density at this site to be 11 294 salamanders ha^?1, amounting to 99.30 kg ha^?1 of biomass, an estimate that is six times greater than reported in previous studies. The majority of this biomass was found within the stream, but 22% was found in the surrounding riparian habitat more than 1 m from the stream. Using headwater stream length and area estimates, we extrapolated biomass estimates for black‐bellied salamanders inhabiting stream and riparian microhabitats across the study region. 5. We report one of the largest estimates of secondary consumer biomass for a headwater ecosystem, attesting to the overall productivity of headwater streams. Headwaters are known to be important for ecological and ecosystem processes and our biomass estimates suggest that salamanders are a critical component to these systems.     

Distribution, abundance, and genetic diversity of Clinostomum spp. metacercariae (Trematoda:Digenea) in a modified Ozark stream system

Land-use alterations can have profound influences on faunal distributions, including host-parasite relationships. Yellow grub trematodes ( Clinostomum spp.) have complex life cycles involving 3 hosts: a snail, a fish or amphibian, and a bird. Here, we analyze the distribution, prevalence, intensity, abundance, and genetic diversity of encysting metacercariae of Clinostomum spp. in salamanders and fishes throughout an aquatic system that includes a natural Ozark stream and man-made ponds. We found Clinostomum sp. infecting permanently aquatic Oklahoma salamanders ( Eurycea tynerensis ; 56% prevalence) and larval grotto salamanders ( Eurycea spelaea ) immediately downstream from a man-made pond. However, Clinostomum sp. did not infect any salamanders in the spring that supplies this pond, or in sections farther downstream (~0.5 and 2 km). Metacercariae of Clinostomum sp. were present in ~90% of introduced largemouth bass ( Micropterus salmoides ) in the man-made pond adjunct to the stream. Morphological examination and phylogenetic analyses based on the mitochondrial gene cytochrome oxidase 1 ( Co1 ) and the nuclear ribosomal gene 18S show that fishes and salamanders at this site are primarily infected with Clinostomum marginatum . There is a relatively high degree of mitochondrial haplotype diversity in C. marginatum at this site but no consistent genetic difference between parasites in largemouth bass from the man-made pond and those in salamanders from the stream. Based on the microgeographic distribution and relationships of metacercariae of C. marginatum at this site, we hypothesize that the adjunct man-made pond has created an ecological situation that brings the cercariae of this parasite into contact with novel stream salamander hosts.     

Effects of Timber Management on Pond-Breeding Salamanders

Abstract: Pond-breeding salamanders spend most of their lives in forested habitat surrounding the vernal pools where they breed. Timber harvesting has been demonstrated to have negative impacts on salamander populations due to changes in soil temperature, soil compaction, and general degradation of habitat. However, little is known about how long it takes for harvested forest habitat to once again become suitable for salamanders. Questions also remain as to whether salamanders will use an area that has been harvested in recent years if an older intact forest area is available. We used drift fences and pitfall traps to capture adult spotted salamanders (Ambystoma maculatum) and marbled salamanders (A. opacum) migrating to 3 vernal ponds during their breeding seasons. The study area contained tracts of forest that were clear-cut 11–12 years prior to the study. All 3 ponds were surrounded by areas of clear-cut and intact forest and drift fences were placed in both habitat types. Similar numbers of spotted salamanders entered the ponds from clear-cut and intact forest areas. The number of marbled salamanders migrating to the ponds did not differ between areas of clear-cut and intact forest. These results suggest that clear-cut habitats may become suitable for adult pond-breeding salamanders after a relatively short regeneration period.     

Genetic drift and mutational hazard in the evolution of salamander genomic gigantism

Salamanders have the largest nuclear genomes among tetrapods and, excepting lungfishes, among vertebrates as a whole. Lynch and Conery (2003) have proposed the mutational‐hazard hypothesis to explain variation in genome size and complexity. Under this hypothesis, noncoding DNA imposes a selective cost by increasing the target for degenerative mutations (i.e., the mutational hazard). Expansion of noncoding DNA, and thus genome size, is driven by increased levels of genetic drift and/or decreased mutation rates; the former determines the efficiency with which purifying selection can remove excess DNA, whereas the latter determines the level of mutational hazard. Here, we test the hypothesis that salamanders have experienced stronger long‐term, persistent genetic drift than frogs, a related clade with more typically sized vertebrate genomes. To test this hypothesis, we compared dN/dS and Kr/Kc values of protein‐coding genes between these clades. Our results do not support this hypothesis; we find that salamanders have not experienced stronger genetic drift than frogs. Additionally, we find evidence consistent with a lower nucleotide substitution rate in salamanders. This result, along with previous work showing lower rates of small deletion and ectopic recombination in salamanders, suggests that a lower mutational hazard may contribute to genomic gigantism in this clade.     

Response of stream‐breeding salamander larvae to sediment deposition in southern Appalachian (U.S.A.) headwater streams

1. Increased fine sediment deposition is a prevalent threat to stream biodiversity and has been shown to impact stream‐breeding salamanders negatively. However, their complex life histories make it difficult to determine which stage is affected. 2. We conducted field experiments from 26 August to 11 September 2010 and 11 October to 11 November 2010 in two southern Appalachian headwater streams (U.S.A.) to examine the response of larval salamanders to increased fine sediment deposition. Fine sediment was increased in artificial stream channels by 0, 33 and 67%. The number of larvae observed at the end of the experiments was used to determine whether larval microhabitat selection was influenced by fine sediment deposition. A concurrent survey of aquatic larvae in three nearby streams complemented this experiment. Stream substratum composition at survey sites was quantified to examine the effects of fine sediment on larval salamander abundance. 3. Increases in fine sediment deposition failed to explain the number of larval salamanders detected in stream channels. Similarly, a negligible effect of fine sediment was observed on abundance estimates. 4. These results suggest that fine sediment deposition has a minimal impact on aquatic salamander larvae. Therefore, the effects of increased fine sediment loads on stream‐breeding salamanders may not be the result of deleterious effects on the aquatic larvae but instead may be the result of effects on other stages. Management efforts that consider these other stages are therefore needed to protect stream‐breeding salamander communities.     

Differential behavioural responses of mayflies from streams with and without fish to trout odour

1. In streams, mayflies (Order Ephemeroptera) are at risk from fish feeding visually in the water column. The effect of fish odour on the behaviour of Baetis bicaudatus from a fishless stream and a trout stream was investigated in four large oval tanks supplied with water from the fishless stream.
2. For each mayfly population, mayfly positioning on the substratum and movement in the water column (drift) were measured during the day and night, over 3 days. Brook trout ( Salvelinus fontinalis ) odour was added to two tanks to test the effect of a threat from fish.
3. Throughout the experiment more mayflies from the trout stream were observed on the substratum surface and in the water column during the night than the day, but the magnitude of night drift was less in tanks with fish odour.
4. Baetis from the fishless stream also displayed a nocturnal periodicity in drift and positioning, but their night-time drift was not affected by the presence of fish odour. On the first day of the experiment, however, more mayflies were observed on the substratum surface and drifting in tanks without fish odour during the day.
5. Sensitivity to fish odour may enable mayflies to alter their behaviour according to the risk of predation from fish.     

Differential behavioural responses of mayflies from streams with and without fish to trout odour

1. In streams, mayflies (Order Ephemeroptera) are at risk from fish feeding visually in the water column. The effect of fish odour on the behaviour of Baetis bicaudatus from a fishless stream and a trout stream was investigated in four large oval tanks supplied with water from the fishless stream.
2. For each mayfly population, mayfly positioning on the substratum and movement in the water column (drift) were measured during the day and night, over 3 days. Brook trout ( Salvelinus fontinalis ) odour was added to two tanks to test the effect of a threat from fish.
3. Throughout the experiment more mayflies from the trout stream were observed on the substratum surface and in the water column during the night than the day, but the magnitude of night drift was less in tanks with fish odour.
4. Baetis from the fishless stream also displayed a nocturnal periodicity in drift and positioning, but their night-time drift was not affected by the presence of fish odour. On the first day of the experiment, however, more mayflies were observed on the substratum surface and drifting in tanks without fish odour during the day.
5. Sensitivity to fish odour may enable mayflies to alter their behaviour according to the risk of predation from fish.     

Effects of headwater impoundment and channelization on invertebrate drift

The construction of a flood control impoundment on Twitty's Creek added large numbers of organisms of limnetic origin to the stream ecosystem. However, the number of limnetic organisms per unit volume of water decreased rapidly as the distance downstream from the reservoir increased and, during most sampling periods, made up an insignificant portion of the total drift biomass at 7.2 km downstream. Factors favoring the extended downstream drift of limnetic organisms were high stream discharge and low water temperature.Several taxa of benthic organisms had much lower drift rates in the station immediately below the dam than at other stations and several taxa commonly taken at other stations were not captured immediately below the reservoir outfall. One possible explanation is that these organisms may have longer drift recruitment distances than the distance from the reservoir outfall to the sample location.A comparison of drift densities of organisms of benthic origin and benthic standing crop densities in channeled and unchanneled streams revealed that drift densities were higher in channeled streams than in unchanneled streams for most taxa of invertebrates. In addition, channeled streams appeared to have lower benthic standing crops than unchanneled streams for most taxa of invertebrates.In stream sections impacted by either channelization or the Twitty Lake outfall, the energy dynamics of the stream ecosystems were altered by increased density of drifting invertebrates. From the standpoint of increasing food availability to the fish fauna of the stream, these changes would appear to benefit drift feeding species and negatively impact bottom feeding species.     

Active entry of stream benthic macroinvertebrates into the water column

Field experiments investigated the possible active entry of stream benthos into the water column. Over a 1-year period, sediment baskets were suspended for 24 hours in a stream pool so that only swimming or floating organisms, essentially unaided by current, could colonize them. A variety of benthos, including taxa characteristic of riffles, colonized the baskets, with colonization highest in late summer and negligible in winter.A modified drift net towed through the pool was used to quantitatively sample benthic animals actually in the water column. Nighttime tows captured a diverse, abundant fauna and indicated densities substantially higher than invertebrate drift densities reported in the literature. Daytime tows yielded little. Estimated percentages of the benthos in the water column at a given time were generally < 1.0%.These findings suggest that not all invertebrate drift is the result of passive mechanical removal from the substrate by current.     

Metapopulation persistence and species spread in river networks

River networks define ecological corridors characterised by unidirectional streamflow, which may impose downstream drift to aquatic organisms or affect their movement. Animals and plants manage to persist in riverine ecosystems, though, which in fact harbour high biological diversity. Here, we study metapopulation persistence in river networks analysing stage‐structured populations that exploit different dispersal pathways, both along‐stream and overland. Using stability analysis, we derive a novel criterion for metapopulation persistence in arbitrarily complex landscapes described as spatial networks. We show how dendritic geometry and overland dispersal can promote population persistence, and that their synergism provides an explanation of the so‐called `drift paradox’. We also study the geography of the initial spread of a species and place it in the context of biological invasions. Applications concerning the persistence of stream salamanders in the Shenandoah river, and the spread of two invasive species in the Mississippi‐Missouri are also discussed.     

The relative importance of drift causes for stream insect herbivores across a canopy gradient

A key attribute of riverine food webs is the downstream movement of invertebrates via the water column, or invertebrate drift. Causes of drift include benthic predation, food limitation, and perhaps passive entry, which may occur when invertebrates lose their purchase on stream substrate. However, the relative importance of drift causes is unknown, as is whether the relative importance of drift causes varies across space. Combining observational data on invertebrate herbivore and predator guild densities with in‐stream experiments, we evaluated the relative importance of benthic predation, food limitation, and passive entry as proximate causes of drift for the herbivore guild across the canopy gradient of a montane stream. We found that 1) benthic predation and food limitation were both more important as causes of herbivore drift than passive entry; 2) drift caused by food limitation did not vary with riparian canopy, whereas herbivore density decreased with increasing riparian canopy, and 3) per capita drift increased linearly with increasing density, while per capita drift decreased in a negative hyperbolic fashion with increasing food, indicating that herbivore drift is proportional to herbivore density, and inversely proportional to food. We conclude that invertebrate herbivore drift was overwhelmingly an active process to improve fitness, and that herbivore food did not vary across the canopy gradient, likely because increased herbivory from larger herbivore populations at sunnier sites prevented food from accumulating.     

Drift of ostracod crustaceans in adjacent intermittent and permanent streams

Ostracods were studied in the drift of adjacent permanent and intermittent streams in Southern Ontario. More species were drifting in the permanent stream than in the intermittent one. The latter developed a pool fauna during early summer and stagnant water species were predominant. Both standing and running water species were common in the permanent stream. Eleven were recorded in the drift and all but one of them are strong swimmers. I. bradyi, the only poor swimmer usually lives among vegetation and it is suggested that truly herpobenthic ostracods are less subject to drift than the others. The pattern of ostracod drift over a period of 13 months in those streams was different. The numbers drifting at the upstream and downstream stations of the same stream in a given month was variable. Ostracods were the major component of crustacean drift in both streams. Stream drift is considered as a mechanism of ostracod dispersal.     

Larval salamanders and diel drift patterns of aquatic invertebrates in an Austrian stream

1. Aquatic predators may influence drift periodicity either directly or indirectly (by non‐consumptive effects involving chemical cues). We took drift samples (eight successive 3‐h sampling intervals over a 24‐h period) on five dates (September 2007, March, April, June and August 2008). Samples were taken at three sites (one site with trout throughout the year, two sites without trout but with fire salamander larvae as top predators from April to August, but without vertebrate predators during the rest of the year) in a stream near Vienna, Austria, to examine the effects of predators on drift periodicity. 2. Of 45 331 specimens caught, the most abundant taxa were Ephemeroptera (32.3%; mainly Baetidae), Diptera (21.5%; mainly Chironomidae), Amphipoda (17.4%; all Gammarus fossarum), Plecoptera (5.4%), Coleoptera (3.5%) and Trichoptera (1.2%). For more detailed analyses, we chose Ephemeroptera (Baetidae; n = 13 457) and Amphipoda (G. fossarum; n = 7888), which were numerous on all sampling dates. 3. The number of drifting baetids and amphipods, as well as total drift density, was generally higher at night than by day, although without predators these differences were significant for Gammaridae but not for Baetidae. 4. When broken down to size classes, night–day drift ratios generally were not significantly different from equality in all size classes of baetids when larval fire salamanders and trout were absent. When predators were present, however, baetid drift density was usually higher at night, except in the smallest and largest size classes. In all size classes of G. fossarum, drift density was usually higher at night, whether with or without the top predators. 5. Although we could study predator effects on drift periodicity at three sites on only a single stream, it seems that non‐consumptive effects may affect Baetidae. Salamander larvae, most probably via kairomones, induced a shift towards mainly nocturnal drift, which could be interpreted as predator avoidance.     

Trout affect the density, activity and feeding of a larval plethodontid salamander

1. Ecologists have struggled to describe general patterns in the impacts of predators on stream prey, particularly at large, realistic spatial and temporal scales. Among the confounding variables in many systems is the presence of multiple predators whose interactions can be complex and unpredictable. 2. We studied the interactions between brook trout (Salvelinus fontinalis) and larval two‐lined salamanders (Eurycea bislineata), two dominant vertebrate predators in New England stream systems, by examining patterns of two‐lined salamander abundance in stream reaches above and below waterfalls that are barriers to fish dispersal, by measuring the effects of trout on salamander density and activity using a large‐scale manipulation of brook trout presence, and by conducting a small‐scale laboratory experiment to study how brook trout and larval two‐lined salamanders affect each other's prey consumption. 3. We captured more salamanders above waterfalls, in the absence of trout, than below waterfalls where trout were present. Salamander density and daytime activity decreased following trout addition to streams, and salamander activity shifted from aperiodic to more nocturnal with fish. Analysis of stomach contents from our laboratory experiment revealed that salamanders eat fewer prey with trout, but trout eat more prey in the presence of salamanders. 4. We suggest that as predators in streams, salamanders can influence invertebrate prey communities both directly and through density‐ and trait‐mediated interactions with other predators.     

Evaluating the effects of urbanisation on salamander abundances using a before‐after control‐impact design

1. Urbanisation represents a significant threat to semi‐aquatic amphibian populations, especially stream‐dwelling salamanders. Although studies of urbanisation effects on amphibians have been conducted, there is an urgent need to follow populations over longer time periods, account for imperfect detection and determine the response time to urbanisation. Consequently, we used a before‐after control‐impact (BACI) study design to estimate changes in abundances of larval and adult salamanders in streams affected by urbanisation. 2. From 2005 to 2009, we used standard sampling techniques to obtain a count of salamanders in 13 first‐order streams that underwent urbanisation of their catchments after the first year of sampling. Simultaneously, we counted salamanders in 17 streams that experienced no disturbance within stream catchments. Additionally, we measured environmental variables at each stream. 3. We used Royle’s binomial mixture model to estimate annual mean abundances and individual detection probabilities, and Bayesian inference was used to estimate population parameters for each stage and species. 4. Although mean abundance estimates varied among years in control and urbanised streams, we found that urbanisation had a negative effect on larval and adult salamander abundances. Larval salamander abundances at sites 1 year after urbanisation were significantly lower than abundances from control sites. Abundances of adult two‐lined salamanders (Eurycea cirrigera) at urbanised sites were lower than abundances at control sites 2 years post‐urbanisation, and adult dusky salamander (Desmognathus fuscus) abundances at urbanised sites were lower than abundances at control sites 3 years post‐urbanisation. Maximum conductivity, sedimentation level and maximum stream channel width differed between urban and non‐urban streams. 5. Our results suggest that stream‐dwelling salamanders exhibit little resistance to urbanisation. Our study also highlights the use of the BACI design to study how urbanisation affects populations in semi‐aquatic habitats. We emphasise that inferences regarding urbanisation effects on population response may be compromised unless urban populations are compared to populations in control sites, especially for species in which populations fluctuate.     

The drift distances and time spent in the drift by freshwater shrimps, Gammarus pulex, in a small stony stream, and their implications for the interpretation of downstream dispersal

1. The objectives were (i) to determine experimentally and to model the relationship between mean water velocity and both the mean distance travelled, and the mean time spent, in the drift by freshwater shrimps, Gammarus pulex; (ii) to develop a drift distance–water velocity model from the experimental study, and validate it with field data; (iii) to examine the relationship between drift rate, water velocity and benthic density with the latter expressed as a mean value for the whole stream and a mean value corrected for the distance travelled in the drift. 2. In field experiments at 10 water velocities (0.032–0.962 m s^?1), the significant relationship between the mean drift distance and mean water velocity was described both by a power function (power, 0.96) and a linear relationship. The mean drift time was fairly constant at 8.3 s (95% CL ± 0.4). A simple model estimated the drift distance and time spent in the drift by different percentages of the drifting invertebrates. This model predicted correctly the positive relationship between drift rate and water velocity for field data over a year. 3. The relationship between drift rate per hour and the independent variables, water velocity and benthic density, was well described by a multiple‐regression model. Adding temperature and date did not improve model fit. Variations in water velocity and benthic density explained 96% of the variation in nocturnal drift rate (65% to velocity, 31% to benthic density), but only 40% of the variation in diurnal drift rate (29% to velocity, 11% to benthic density). Correcting benthic density for the drift distances did not improve model fit. 4. The significance of this study is that it developed models to predict drift distances and time, values being similar to those obtained in another, larger stream. It also illustrated the importance of spatial scale in the interpretation of drift by showing that when drift distances were taken into account, the impact of drift on the population was higher (4–10% lost day^?1) than when drift distances were ignored (usually < 3% lost day^?1), especially at a local level.     

Incorporating invertebrate predators into theory regarding the timing of invertebrate drift

Theory concerning the timing of lotic invertebrate drift suggests that daytime-feeding fish cause invertebrates to restrict their drift behavior to the nighttime. However, there is growing evidence that the nighttime foraging of invertebrate predators also contributes to the nocturnal timing of drift, though it is unclear whether the nocturnal behavior of invertebrate predators is innate or proximately caused by fish. In two experiments, one conducted in a fish-bearing stream and a second in a fishless stream, we compared the drift patterns of Baetidae (Ephemeroptera) from channels with and without benthic invertebrate predators. We tested whether invertebrate predators affect the timing of drift, either as a proximate cause of nocturnal drift in the fishless stream (diel periodicity) or as a proximate cause of a pre-dawn peak in drift in the fish-bearing stream (nocturnal periodicity). In the fish-bearing stream experiment, a pre-dawn increase of baetid drift occurred independently of invertebrate predators, indicating that invertebrate predators were not the proximate cause of nocturnal periodicity in the stream. In the fishless stream experiment, invertebrate predators caused more baetid drift at night than during the day, indicating that invertebrate predators caused the nocturnal drift pattern we observed in the stream, and that invertebrate predators can influence drift timing independently of fish. Therefore, we suggest that both visually feeding fish and nocturnally foraging benthic predators, when present, affect the timing of invertebrate drift; visually feeding fish by reducing daytime drift, and benthic predators by increasing nighttime drift.     

The effect of current velocity and sediment on the drift of the mayfly Ephemerella subvaria Mcdunnough

SUMMARY. Experiments conducted in an artificial stream showed that significantly more nymphs drifted from an inorganic substrate at a mean current velocity of 28.5 cm s⁻¹ than at 18.5 cm s⁻¹. Drift density, however, was not affected. Disproportionately large numbers of nymphs drifted while current velocities were being increased from 18.5 to 28.5 cm s⁻¹.
Both drift numbers and drift density were greater in turbid water, after the addition of large amounts of inorganic sediment, than under clear-flowing conditions during dark periods but not in the light. The interaction of increasing current velocity and sediment levels resulted in a significantly greater number of drifting nymphs under lighted conditions.
Minor spates which do not seriously disturb the stream bed may initiate significant increases in macroinvertebrate drift.     

Stream drift,size-specific predation,and the evolution of ovum size in an amphibian

Summary A stream-breeding race of small-mouthed salamanders (Ambystoma texanum) in central Kentucky produces ova that are twice as large as those of a pond-breeding race found nearby. Embryos of stream-breeders also hatch at a more advanced developmental stage than those of pond-breeders. Morphological evidence indicates that stream-breeders were derived from pond-breeding stock. Assuming that differences between stream and pond-breeders reflect evolutionary change, and that the ancestral pond stock that invaded streams was similar to extant pond-breeders, we examined three hypotheses that might explain changes in ovum size and stage at hatching following the invasion of streams. (1) Larger ovum size evolved indirectly as a consequence of selection for rapid development which minimizes mortality risk from stream drying. (2) Increased ovum (hatchling) size and stage at hatching of stream-breeders are adaptations to resist stream current. (3) Increased ovum (hatchling) size and stage at hatching are adaptations to reduce predation on hatchlings from stream invertebrates. The results of field and laboratory studies only support hypotheses (2) and (3). Hatchlings that were relatively large or at a more advanced developmental stage had slower drift rates and were less vulnerable to predation by Phagocata gracilis, a flatworm abundant in streams in central Kentucky. Developmental and growth parameters were not correlated significantly with ovum size in populations of either geographic race. Differences in degree of parental care among races also cannot explain variation in ovum size since both races abandon their eggs immediately after oviposition.     

Molecular detection of vertebrates in stream water: a demonstration using Rocky Mountain tailed frogs and Idaho giant salamanders

Stream ecosystems harbor many secretive and imperiled species, and studies of vertebrates in these systems face the challenges of relatively low detection rates and high costs. Environmental DNA (eDNA) has recently been confirmed as a sensitive and efficient tool for documenting aquatic vertebrates in wetlands and in a large river and canal system. However, it was unclear whether this tool could be used to detect low-density vertebrates in fast-moving streams where shed cells may travel rapidly away from their source. To evaluate the potential utility of eDNA techniques in stream systems, we designed targeted primers to amplify a short, species-specific DNA fragment for two secretive stream amphibian species in the northwestern region of the United States (Rocky Mountain tailed frogs, Ascaphus montanus, and Idaho giant salamanders, Dicamptodon aterrimus). We tested three DNA extraction and five PCR protocols to determine whether we could detect eDNA of these species in filtered water samples from five streams with varying densities of these species in central Idaho, USA. We successfully amplified and sequenced the targeted DNA regions for both species from stream water filter samples. We detected Idaho giant salamanders in all samples and Rocky Mountain tailed frogs in four of five streams and found some indication that these species are more difficult to detect using eDNA in early spring than in early fall. While the sensitivity of this method across taxa remains to be determined, the use of eDNA could revolutionize surveys for rare and invasive stream species. With this study, the utility of eDNA techniques for detecting aquatic vertebrates has been demonstrated across the majority of freshwater systems, setting the stage for an innovative transformation in approaches for aquatic research.