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Geology topics

R. Bruce Bury

Publications and source records attributed to R. Bruce Bury.

At least 37 records · Page 2Linked to original sources
USGS2004

Terrestrial movements of juvenile and adult tailed frogs in relation to timber harvest in coastal British Columbia

Tailed frog (Ascaphus truei Stejneger) populations are at risk in much of the Pacific Northwest, and recolonization of sites may be slow postlogging. To examine the terrestrial movements of Ascaphus in clearcuts and old growth, we employed pitfall traps and drift-fence arrays installed along streams and 100 m into upland habitat. In the fall, we captured frogs farther from streams in old growth than in clearcuts, and more frogs were captured a??25 m from streams in clearcuts. Stronger stream affinity in clearcuts was most evident with juvenile frogs, which exhibited more upstream movements than adults. Compared with inland sites where frogs remained close to streams (e.g., 12 m), frogs at our coastal sites were captured at greater distances from streams (a?Y100 m), having lower stream affinity than frogs at inland sites. Long-distance overland movements appear more likely where forested stands are present. Aggregations of Ascaphus at individual streams may not represent distinct populations and should not be managed as distinct units. Preserving groups of interconnected streams within watersheds instead of individual streams will improve the conservation status of Ascaphus. Population monitoring can ensure conservation measures promote long-term persistence.

Canadian Journal of Forest Research↗
USGS2003

Indirect facilitation of an anuran invasion by non-native fishes

Positive interactions among non-native species could greatly exacerbate the problem of invasions, but are poorly studied and our knowledge of their occurrence is mostly limited to plant-pollinator and dispersal interactions. We found that invasion of bullfrogs is facilitated by the presence of co-evolved non-native fish, which increase tadpole survival by reducing predatory macroinvertebrate densities. Native dragonfly nymphs in Oregon, USA caused zero survival of bullfrog tadpoles in a replicated field experiment unless a non-native sunfish was present to reduce dragonfly density. This pattern was also evident in pond surveys where the best predictors of bullfrog abundance were the presence of non-native fish and bathymetry. This is the first experimental evidence of facilitation between two non-native vertebrates and supports the invasional meltdown hypothesis. Such positive interactions among non-native species have the potential to disrupt ecosystems by amplifying invasions, and our study shows they can occur via indirect mechanisms.

Ecology Letters↗
USGS2003

Differences in habitat use by blanding's turtles, Emydoidea blandingii, and painted turtles, Chysemys picta, in the Nebraska sandhills

We sampled a variety of wetlands in the Nebraska sandhills at Valentine National Wildlife Refuge. Significantly more individuals of painted turtles ( Chrysemys picta ) occurred in lakes and open waters than in marshes or small ponds, and the opposite was true for Blanding's turtles ( Emydoidea blandingii ). Besides this marked difference in habitat use, 46% of the captured E. blandingii in pond/marsh habitat were juveniles, but only 31.6% in lakes and open water. Current information suggests that marshes and small ponds are important habitat for juvenile turtles, especially Emydoidea blandingii .

Nebraska↗
USGS2003

Organochlorine pesticides, PCBs, trace elements and metals in western pond turtle eggs from Oregon

With increased concern over the status of reptile populations globally, contaminant studies should be part of species evaluations. We analyzed eggs of western pond turtles from Fern Ridge Reservoir in western Oregon for 20 organochlorine (OC) pesticides or metabolites, 42 congener-specific polychlorinated biphenyls (PCBs), and 16 trace elements or metals. These eggs represent the first of this species analyzed. The OC pesticides and PCB residue concentrations in the western pond turtle eggs were generally low and similar to those found in eggs of snapping turtles from a remote site in Ontario, Canada. Western pond turtle eggs also contained mercury and chromium, which are metals of special concern. Although few reptilian eggs have been analyzed for metals, the 44.9 mug/g dry weight chromium in a western pond turtle egg in this study may be the highest reported in a reptilian egg. We found no significant difference in contaminant concentrations in eggs from nests in Oregon, where all turtle eggs failed to hatch compared to those where some eggs hatched. During this initial project, however, we were unable to assess fully the role of OCs, PCBs and other contaminants in the western pond turtle decline. Factors other than contaminants may be involved. In another study, snapping turtle eggs near the Great Lakes-St. Lawrence River basin were much more contaminated with evidence reported of effects on sex differentiation and reproductive endocrine function. Egg hatchability, the only reproductive parameter monitored, may not be the most sensitive endpoint. Other endpoints, including endocrine function, deformity rates, growth rates, and sex determination need study.

Northwest Science↗
USGS2002

The endemic headwater stream amphibians of the American Northwest: Associations with environmental gradients in a large forested preserve

We used a large forested preserve (Olympic National Park, USA) to examine the habitat associations of a unique and environmentally sensitive stream amphibian fauna: Ascaphus truei Stegneger, Rhyacotriton olympicus (Gaige) and Dicamptodon copei Nussbaum. We quantified the relative abundance of stream amphibians and compared them to physical, topographic, climatic and landscape variables. All three species were associated with the south-west to north-east climate gradient, tending to be most abundant in the south-west. Although a habitat generalist relative to the other two species, Dicamptodon copei was absent from the north-eastern portion of the park. Ascaphus truei and Rhyacotriton olympicus were both associated with coarse substrates and steep gradients. Unlike studies in harvested forests, all stream amphibians were common in waters with unconsolidated surface geology (e.g. marine sediments that erode easily). Studies of ecological preserves can provide an important baseline for evaluating species associations with environmental gradients and can reveal patterns not evident in more disturbed landscapes.

Global Ecology and Biogeography↗
USGS2002

Optical characteristics of natural waters protect amphibians from UV-B in the U.S. Pacific Northwest

Increased exposure to ultraviolet-B (UV-B) radiation has been proposed as a major environmental stressor leading to global amphibian declines. Prior experimental evidence from the U.S. Pacific Northwest (PNW) indicating the acute embryonic sensitivity of at least four amphibian species to UV-B has been central to the literature about amphibian decline. However, these results have not been expanded to address population-scale effects and natural landscape variation in UV-B transparency of water at amphibian breeding sites: both necessary links to assess the importance of UV-B for amphibian declines. We quantified the UV-B transparency of 136 potential amphibian breeding sites to establish the pattern of UV-B exposure across two montane regions in the PNW. Our data suggest that 85% of sites are naturally protected by dissolved organic matter in pond water, and that only a fraction of breeding sites are expected to experience UV-B intensities exceeding levels associated with elevated egg mortality. Thus, the spectral characteristics of natural waters likely mediate the physiological effects of UV-B on amphibian eggs in all but the clearest waters. These data imply that UV-B is unlikely to cause broad amphibian declines across the landscape of the American Northwest.

California, Oregon, Washington↗
USGS2002

Terrestrial and stream amphibians across clearcut-forest interfaces in the Siskiyou Mountains, Oregon

Timber harvest in the Pacific Northwest has resulted in a highly fragmented landscape. but there is no information on responses of amphibians to forest edges for this region. We investigated abundance of terrestrial and stream-dwelling amphibians on the interface of recent clearcuts and mature forest in the Siskiyou Mountains, Oregon, in summer and fall of 1998. We assessed relative abundance of terrestrial -amphibians on four clearcut forest transects with a combination of pitfall trapping and manual searches. Ensantinas and Del Norte salamanders, the most frequently recorded species, were found on all four sites. While we commonly captured ensantinas using both techniques, we caught most Del Norte salamanders during manual searches. For both species we found no differences in abundance associated with distance to forest edge. Lack of differences in salamander abundance among clearcut and adjacent forests may be related lo large amounts of small woody debris that remained in the clearcuts. The abundance of larvae of tailed frogs and Pacific giant salamanders in five headwater streams was markedly lower in clearcuts than in downstream mature forest stands. No obvious differences existed for stream habitat variables across transects. but abundance of metamorphosed individuals and recruitment may be reduced in clearcut areas due lo hotter and drier conditions during

Oregon↗
USGS2001

Association of amphibians with attenuation of ultraviolet-b radiation in montane ponds

Ambient ultraviolet-b (UV-B) radiation (280–320 nm) has increased at north-temperate latitudes in the last two decades. UV-B can be detrimental to amphibians, and amphibians have shown declines in some areas during this same period. We documented the distribution of amphibians and salmonids in 42 remote, subalpine and alpine ponds in Olympic National Park, Washington, United States. We inferred relative exposure of amphibian habitats to UV-B by estimating the transmission of 305- and 320-nm radiation in pond water. We found breeding Ambystoma gracile , A. macrodactylum and Rana cascadae at 33%, 31%, and 45% of the study sites, respectively. Most R. cascadae bred in fishless shallow ponds with relatively low transmission of UV-B. The relationship with UV-B exposure remained marginally significant even after the presence of fish was included in the model. At 50 cm water depth, there was a 55% reduction in incident 305-nm radiation at sites where breeding populations of R. cascadae were detected compared to other sites. We did not detect associations between UV-B transmission and A. gracile or A. macrodactylum . Our field surveys do not provide evidence for decline of R. cascadae in Olympic National Park as has been documented in Northern California, but are consistent with the hypothesis that the spatial distribution of R. cascadae breeding sites is influenced by exposure to UV-B. Substrate or pond depth could also be related to the distribution of R. cascadae in Olympic National Park.

Oecologia↗
USGS2001

Western pond turtles (Clemmys marmorata) in the central valley of California: Status and population structure

A sensitive resettable odometer reading to 0.01 mile facilitated censusing breeding male redwinged blackbirds (Agelaius phoeniceus) from a vehicle. Territorial males along roadsides were 'marked' with recorded mileage readings rather than with landmarks of the types employed by Hewitt for censuses based on the Lincoln index principle. Sensitive odometers that can be reset have many potential uses in wildlife investigations.

Transactions of the Western Section of the Wildlif↗
USGS2001

Clutch sizes and nests of tailed frogs from the Olympic Peninsula, Washington

In the summers 1995-1998, we sampled 168 streams (1,714 in of randomly selected 1-m bands) to determine distribution and abundance of stream amphibians in Olympic National Park, Washington. We found six nests (two in one stream) of the tailed frog, compared to only two nests with clutch sizes reported earlier for coastal regions. This represents only one nest per 286 in searched and one nest per 34 streams sampled. Tailed frogs occurred only in 94 (60%) of the streams and, for these waters, we found one nest per 171 in searched or one nest per 20 streams sampled. The numbers of eggs for four masses ((x) over bar = 48.3, range 40-55) were low but one single strand in a fifth nest had 96 eggs. One nest with 185 eggs likely represented communal egg deposition. Current evidence indicates a geographic trend with yearly clutches of relatively few eggs in coastal tailed frogs compared to biennial nesting with larger clutches for inland populations in the Rocky Mountains.

Northwest Science↗
USGS2000

Response of hatchling and yearling turtles to thermal gradients: Comparison of Chelydra serpentina and Trachemys scripta

In laboratory tests, young Chelydra serpentina and Trachemys scripta altered their distribution in the presence of a temperature gradient. Selection of temperatures in the gradient for hatchlings and yearlings showed that body temperatures ( T b s) of C. serpentina were lower than T. scripta , but the difference was insignificant. Relatively low T b s could allow greater activity range and reduced metabolic maintenance cost for C. serpentina , which seldom leaves water.

Journal of Thermal Biology↗
USGS1999

A historical perspective and critique of the declining amphibian crisis

Losses of amphibian species and populations are of global concern (Blaustein and Wake 1990, Wyman 1990, Wake 1991, Vial and Saylor 1993, Blaustein 1994) and have been the focus of an increasing number of studies. Still, neither all regions nor all species have declines (Dodd 1997; Green 197; Corn, in press). There also is wide variation in abundance of many species over different years (Pechmann et al. 1991, Meyer et al. 1998); consequently, natural variation needs to be clearly separated from regional declines in populations.

Wildlife Society Bulletin↗