Geology topics

Robert G. Bramblett

Publications and source records attributed to Robert G. Bramblett.

8 recordsLinked to original sources

USGS2021

Movements of selected minnows between the lower Yellowstone River and its tributaries

Reduced population connectivity has been implicated as a cause of decreased distributions and abundances of many Great Plains fishes. However, scant empirical evidence quantifying movement and relating the contribution of spatial linkages to population abundances and resilience exists. We used otolith microchemistry analysis to characterize the movements of western silvery minnows ( Hybognathus argyritis Girard, 1856), flathead chubs ( Platygobio gracilis (Richardson, 1836)), and sand shiners ( Notropis stramineus (Cope, 1865)) between the Yellowstone River and its tributaries. Sixty-nine percent of western silvery minnows, 65% of flathead chubs, and 42% of sand shiners moved between the Yellowstone River and tributaries. Mean total number of interchanges was highest among western silvery minnows (4.8 interchanges/mover), intermediate among flathead chubs (4.3 interchanges/mover), and lowest among sand shiners (1.4 interchanges/mover; P < 0.01). Natal movements were rare, but juvenile movements were common and frequent among all three species. Movements between main-stem and tributary habitats are probably prominent facets of the life cycles of other Great Plains minnows. Therefore, connectivity among such habitats should be a high conservation priority to enhance the long-term viability of such fishes.

Great Plains, Yellowstone River↗

USGS2019

Riverine turtles select habitats maintained by natural discharge regimes in an unimpounded large river

Turtle populations are imperiled worldwide, but limited ecological information from unaltered systems hampers science‐based management and conservation of some species, especially riverine turtles such as the spiny softshell ( Apalone spinifera ). We therefore investigated movements and spatial habitat selection of 54 A . spinifera in 633 river kilometres (rkm) of the least‐altered river in the conterminous United States—the Yellowstone River in Montana—from 2005 to 2009. Movement rates and home ranges were smaller than in fragmented, altered river systems because nesting and overwintering habitats were common and in close proximity. Habitat selection also differed. A . spinifera in the Yellowstone River overwintered in unaltered bluff pools and summered in complex reaches with side channels, islands, and diverse habitats. However, those in the highly altered Missouri River used deep alluvial pools for overwintering and flooded, inundated, or backwatered tributary mouths in spring and summer. Importantly, selected habitats in both rivers were functionally similar, including complex river reaches (with multiple channels, islands, and diverse habitats) and natural pool types. Unfortunately, these are the very habitats that are limited in rivers affected by dams, bank stabilization, and channelization. Therefore, preservation of natural and diverse riverine habitats—and the fluvial dynamics that maintain them—may enhance conservation of A . spinifera in large rivers.

Montana, North Dakota, South Dakota, Wyoming↗

USGS2018

Landscape assessment of side channel plugs and associated cumulative side channel attrition across a large river floodplain

Determining the influences of anthropogenic perturbations on side channel dynamics in large rivers is important from both assessment and monitoring perspectives because side channels provide critical habitat to numerous aquatic species. Side channel extents are decreasing in large rivers worldwide. Although riprap and other linear structures have been shown to reduce side channel extents in large rivers, we hypothesized that small “anthropogenic plugs” (flow obstructions such as dikes or berms) across side channels modify whole-river geomorphology via accelerating side channel senescence. To test this hypothesis, we conducted a geospatial assessment, comparing digitized side channel areas from aerial photographs taken during the 1950s and 2001 along 512 km of the Yellowstone River floodplain. We identified longitudinal patterns of side channel recruitment (created/enlarged side channels) and side channel attrition (destroyed/senesced side channels) across n = 17 river sections within which channels were actively migrating. We related areal measures of recruitment and attrition to the density of anthropogenic side channel plugs across river sections. Consistent with our hypothesis, a positive spatial relationship existed between the density of anthropogenic plugs and side channel attrition, but no relationship existed between plug density and side channel recruitment. Our work highlights important linkages among side channel plugs and the persistence and restoration of side channels across floodplain landscapes. Specifically, management of small plugs represents a low-cost, high-benefit restoration opportunity to facilitate scouring flows in side channels to enable the persistence of these habitats over time.

Montana↗

USGS2018

Factors affecting nesting ecology of Apalone spinifera in a northwestern Great Plains river of the United States

The nesting ecology of Apalone spinifera in large North American rivers is largely unknown despite the wide distribution of the species in these naturally dynamic ecosystems. We describe the nesting locations, timing, behavior, and habitat of A. spinifera in relation to natural and anthropogenic factors in the Missouri River. Nesting followed annual peak river stage, mostly occurred in the afternoon when air temperatures were 25°–30°C, and did not occur when human activity was nearby. Apalone spinifera nested in June in a year with average discharge (2012), but nested 20 d later in a year with a large flood event (2011). During the average discharge year, 90% of nests were found on islands, but similar proportions of nests were found on island and mainland habitats during the flood year because many islands were inundated. Nests were mostly in mixed-gravel substrates where vegetation cover was sparse or absent. Depredation occurred only after the emergence of hatchlings (∼ 60 d after nesting) and more often on nests on the mainland than on islands. Emergence rates were ∼ 1.5 times higher in the average year than the flood year, and emergence rates were higher in mixed-gravel nests than in pure-sand nests in 2011. In artificial nests, incubation temperatures averaged ∼ 4.3°C higher in mixed-gravel than in sand substrates, and freezing temperatures in winter penetrated to depths greater than the mean egg chamber depth (7.5 cm) for up to 3 wks. Therefore, incubation might be accelerated in mixed-gravel substrates. Accelerated incubation would enhance reproductive success because freezing temperatures preclude hatchlings from overwintering in nests in our study area. Mountain snowmelt-driven hydrology, coupled with the onset of freezing temperatures in autumn, might create a temporal “runoff-freeze squeeze” that limits the successful reproduction of A. spinifera in some years. However, high runoff also scoured vegetation from shorelines where A. spinifera nested in subsequent years. Natural variation in annual discharge might therefore be crucial to conservation of A. spinifera in large rivers.

Chelonian Conservation and Biology↗

USGS2017

Spatially dependent responses of a large-river fish assemblage to bank stabilization and side channels

The alteration of rivers by anthropogenic bank stabilization to prevent the erosion of economically valuable lands and structures has become commonplace. However, such alteration has ambiguous consequences for fish assemblages, especially in large rivers. Because most large, temperate rivers have impoundments, it can be difficult to separate the influences of bank stabilization structures from those of main-stem impoundments, especially because both stabilization structures and impoundments can cause side-channel loss. Few large rivers are free flowing and retain extensive side channels, but the Yellowstone River (our study area) is one such river. We hypothesized that in this river (1) bank stabilization has changed fish assemblage structure by altering habitats, (2) side-channel availability has influenced fish assemblage structure by providing habitat heterogeneity, and (3) the influences of bank stabilization and side channels on fish assemblages were spatially scale dependent. We developed a spatially explicit framework to test these hypotheses. Fish assemblage structure varied with the extent of bank stabilization and the availability of side channels; however, not all assemblage subsets were influenced. Nevertheless, bank stabilization and side channels had different and sometimes opposite influences on the fish assemblage. The effects of side channels on fish were more consistent and widespread than those of bank stabilization; the catches of more fishes were positively correlated with side-channel availability than with the extent of bank stabilization. The influences of bank stabilization and side channels on the relative abundances of fish also varied, depending on species and river bend geomorphology. The variation in river morphology probably contributed to the assemblage differences between stabilized and reference river bends; stabilized alluvial pools were deeper than reference alluvial pools, but the depths of stabilized and reference bluff pools did not differ. The strengths of the relationships among fish assemblages, bank stabilization, and side channels were spatially scale dependent; optimum spatial scales ranged from less than 200 m to 3,200 m up- and downstream, suggesting that bank stabilization and side channels influenced fish assemblages across multiple spatial scales.

Montana↗

USGS2017

Spatiotemporal ecology of Apalone spinifera in a large, Great Plains river ecosystem

Sparse information exists about the ecology of Spiny Softshell Turtles (Apalone spinifera) in large rivers, at the northwestern extent of their natural range, and in Montana, where they are disjunct from downstream populations and a State Species of Concern. We determined spatiotemporal ecology of 47 female and 12 male turtles from 2009 through 2012 and identified fundamental habitats in the Missouri River in east-central Montana. Movement rates of females were greater than those of males and peaked before nesting. Movement rates of males peaked before overwintering, and movement rates of both sexes were minimal in winter. Home range sizes were not different between sexes, varied among individuals and seasons, and were similar to those reported elsewhere in their northern range. Turtles aggregated and showed interannual fidelity to separate and disparate habitats in different seasons. Turtles often chose fine substrates, tributary confluences, and reaches with islands during summer and mainstem outside bends in the winter. They inhabited shallow, slow water velocity areas from May to September. They inhabited deeper, moderate velocity areas from October to April. We did not observe ice jams and associated riverbed scour at hibernacula, but did observe them elsewhere. Ice jams may be spatially predictable and influence the distribution of riverine turtles during autumn and winter. Preservation of dissimilar habitats used during major portions of the life cycle (lateral habitats, islands, and hibernacula) and natural streamflow patterns, which influenced timing of habitat availability and turtle movement, may facilitate continued existence of Spiny Softshell Turtles in the Missouri River in Montana

Herpetological Conservation and Biology↗

USGS2016

Comparative use of side and main channels by small-bodied fish in a large, unimpounded river

Ecological theory and field studies suggest that lateral floodplain connectivity and habitat heterogeneity provided by side channels impart favourable habitat conditions for lotic fishes, especially fluvial fishes dependent on large patches of shallow, slow velocity habitats for some portion of their life cycle. However, anthropogenic modification of large, temperate floodplain rivers has led to extensive channel simplification and side-channel loss. Highly modified rivers consist of simplified channels in contracted, less dynamic floodplains. Most research examining the seasonal importance of side channels for fish assemblages in large rivers has been carried out in heavily modified rivers, where side-channel extents are substantially reduced from pre-settlement times, and has often overlooked small-bodied fishes. Inferences about the ecological importance of side channels for small-bodied fishes in large rivers can be ascertained only from investigations of large rivers with largely intact floodplains. The Yellowstone River, our study area, is a rare example of one such river. We targeted small-bodied fishes and compared their habitat use in side and main channels in two geomorphically distinct types of river bends during early and late snowmelt runoff, and autumn base flow. Species compositions of side and main channels differed throughout hydroperiods concurrent with the seasonal redistribution of the availability of shallow, slow current-velocity habitats. More species of fish used side channels than main channels during runoff. Additionally, catch rates of small fishes were generally greater in side channels than in main channels and quantitative assemblage compositions differed between channel types during runoff, but not during base flow. Presence of and access to diverse habitats facilitated the development and persistence of diverse fish assemblages in our study area. Physical dissimilarities between side and main channels may have differentially structured the side- and main-channel fish assemblages during runoff. Patches of shallow, slow current-velocity (SSCV) habitats in side channels were larger and had slightly slower water velocities than SSCV habitat patches in main channels during runoff, but not during base flow. Our findings establish a baseline importance of side channels to riverine fishes in a large, temperate river without heavy anthropogenic modification. Establishing this baseline contributes to basic fluvial ecology and provides empirical justification for restoration efforts that reconnect large rivers with their floodplains.

Montana↗

USGS2016

Distributions of small nongame fishes in the lower Yellowstone River

The Yellowstone River is the longest unimpounded river in the conterminous United States. It has a relatively natural flow regime, which helps maintain diverse habitats and fish assemblages uncommon in large rivers elsewhere. The lower Yellowstone River was thought to support a diverse nongame fish assemblage including several species of special concern. However, comprehensive data on the small nongame fish assemblage of the lower Yellowstone River is lacking. Therefore, we sampled the Yellowstone River downstream of its confluence with the Clark’s Fork using fyke nets and otter trawls to assess distributions and abundances of small nongame fishes. We captured 42 species (24 native and 18 nonnative) in the lower Yellowstone River with fyke nets. Native species constituted over 99% of the catch. Emerald shiners Notropis atherinoides , western silvery minnows Hybognathus argyritis , flathead chubs Platygobio gracilis , sand shiners Notropis stramineus , and longnose dace Rhinichthys cataractae composed nearly 94% of fyke net catch and were caught in every segment of the study area. We captured 24 species by otter trawling downstream of the Tongue River. Sturgeon chubs Macrhybopsis gelida , channel catfish Ictalurus punctatus , flathead chubs, stonecats Noturus flavus , and sicklefin chubs Macrhybopsis meeki composed 89% of the otter trawl catch. The upstream distributional limit of sturgeon chubs in the Yellowstone River was the Tongue River; few sicklefin chubs were captured above Intake Diversion Dam. This study not only provides biologists with baseline data for future monitoring efforts on the Yellowstone River but serves as a benchmark for management and conservation efforts in large rivers elsewhere as the Yellowstone River represents one of the best references for a naturally functioning Great Plains river.

Montana↗