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Resource selection and species interactions between native and non-native fishes in a simulated stream system

Effective fishery management necessitates understanding of resource partitioning by fishes that inhabit complex systems composed of biotic and abiotic features. Evaluations of non-native species introductions have continually demonstrated adverse effects associated with abundance and distribution of native fishes. Therefore, understanding resource selection and interactions between native and non-native species is important for recovery efforts. Habitat use by two native fish species (largescale sucker Catostomus macrocheilus [Girard] and mountain whitefish Prosopium williamsoni [Girard]) and one non-native fish species (pumpkinseed Lepomis gibbosus [Linnaeus]) of the Kootenai River, Idaho, were evaluated in a laboratory stream system. Trials were conducted in allopatry and in sympatry with and without the presence of wood to describe habitat selection in the context of on-going habitat rehabilitation efforts. Interactions were evident between native largescale sucker and non-native pumpkinseed concerning use of a woody structure and current velocity. Mountain whitefish used low-velocity habitats and selected locations that were further from wood when in sympatry with pumpkinseed. Our research suggests that habitat use of native, large-river fishes may be influenced by the presence of a non-native species, and that considering such interactions is critical when designing and implementing habitat rehabilitation efforts in river ecosystems.

Fisheries Management and Ecology

Ontogenetic and among-individual variation in foraging strategies of northeast Pacific white sharks based on stable isotope analysis

There is growing evidence for individuality in dietary preferences and foraging behaviors within populations of various species. This is especially important for apex predators, since they can potentially have wide dietary niches and a large impact on trophic dynamics within ecosystems. We evaluate the diet of an apex predator, the white shark ( Carcharodon carcharias ), by measuring the stable carbon and nitrogen isotope composition of vertebral growth bands to create lifetime records for 15 individuals from California. Isotopic variations in white shark diets can reflect within-region differences among prey (most importantly related to trophic level), as well as differences in baseline values among the regions in which sharks forage, and both prey and habitat preferences may shift with age. The magnitude of isotopic variation among sharks in our study (>5‰ for both elements) is too great to be explained solely by geographic differences, and so must reflect differences in prey choice that may vary with sex, size, age and location. Ontogenetic patterns in δ 15 N values vary considerably among individuals, and one third of the population fit each of these descriptions: 1) δ 15 N values increased throughout life, 2) δ 15 N values increased to a plateau at ~5 years of age, and 3) δ 15 N values remained roughly constant values throughout life. Isotopic data for the population span more than one trophic level, and we offer a qualitative evaluation of diet using shark-specific collagen discrimination factors estimated from a 3+ year captive feeding experiment (Δ 13 C shark-diet and Δ 15 N shark-diet equal 4.2‰ and 2.5‰, respectively). We assess the degree of individuality with a proportional similarity index that distinguishes specialists and generalists. The isotopic variance is partitioned among differences between-individual (48%), within-individuals (40%), and by calendar year of sub-adulthood (12%). Our data reveal substantial ontogenetic and individual dietary variation within a white shark population.

PLoS ONE

Water quality and algal conditions in the North Umpqua River, Oregon, 1995-2007, and their response to Diamond Lake restoration

The Wild and Scenic North Umpqua River is one of the highest-quality waters in the State of Oregon, supporting runs of wild salmon, steelhead, and trout. For many years, blooms of potentially toxic blue-green algae in Diamond and Lemolo Lakes have threatened water quality, fisheries, and public health. The blooms consist primarily of Anabaena , a nitrogen (N)-fixing planktonic alga that appears to have contributed to N enrichment, which could account for changes in communities and biomass of periphyton, or attached benthic algae, in the river. Periphyton can become a nuisance in summer by affecting riffle habitat and causing high pH that fails to meet State of Oregon water-quality standards. These symptoms of nutrient enrichment in the North Umpqua River were first documented in 1995, and the symptoms have continued since then. Restoring natural ecosystem processes that store nutrients rather than fueling algae might help improve pH and water-clarity conditions. This report summarizes the results from a study in 2005–07 characterizing water quality and algal conditions in the North Umpqua River before, during, and after the 2006 rotenone treatment of Diamond Lake in the headwaters of the North Umpqua River. The treatment was part of a restoration project to eradicate Tui chub ( Gila bicolor ), a non-native invasive fish blamed for decimating the trout fishery in Diamond Lake and fueling Anabaena blooms. Diamond Lake was expected to contribute organic matter and associated nutrients to Lake Creek during the project, but it was unclear whether these nutrients would affect periphyton communities in the North Umpqua River downstream. This study also provided an opportunity to examine changes in stream conditions in the main stem North Umpqua River and its tributaries, which were previously sampled in July 1995. The 1995 study was designed to provide background data during relicensing of the upstream hydroelectric facilities, and was partly motivated by anecdotal concerns about increase periphyton growth and reduced water clarity. As part of the 2005–07 study associated with the Diamond Lake restoration project, we repeated the 1995 basinwide synoptic survey in 2005, before the rotenone treatment. Although both samplings were just a snapshot of conditions, these data were evaluated for possible changes between 1995 and 2005.

Oregon

Behavioral responses of Pacific lamprey to alarm cues

Pacific lamprey ( Entosphenus tridentatus ), an anadromous ectoparasite, faces several challenges during adult migration to spawning grounds. Developing methods to address these challenges is critical to the success of ongoing conservation efforts. The challenges are diverse, and include anthropogenic alterations to the ecosystem resulting in loss of habitat, impassable barriers such as dams, climate change impacts, and altered predator fields. We conducted a behavioral study to understand how adult migrating Pacific lamprey respond to potential alarm cues: White Sturgeon ( Acipenser transmontanus ), human saliva, decayed Pacific lamprey, and river otter ( Lontra canadensis ). Research has shown that some species of lamprey can be guided to a location using odors and similar cues may be useful as a management tool for Pacific lamprey. Experiments were conducted over 2 nights and measured the number of entries (count) and duration of time spent (occupancy) by adult lamprey in each arm of a two-choice maze. During the first night, no odor was added to test for selection bias between arms. During the second night odor was added to one arm of the maze. Contrary to expectations, lamprey were significantly attracted to the river otter odor in both count and occupancy. No significant differences were found in the response of lamprey to the other three odors. Results from this study indicate that Pacific lamprey do respond to some odors; however, additional tests are necessary to better identify the types of odors and concentrations that elicit a repeatable response.

Oregon, Washington

Genetic analysis of federally endangered Cape Sable seaside sparrow subpopulations in the Greater Everglades, USA

The federally endangered Cape Sable seaside sparrow ( Ammospiza maritima mirabilis ) is endemic to the Greater Everglades ecosystem in southern Florida, inhabiting fragmented marl prairies in six individual subpopulations. The subspecies is threatened by loss of breeding habitat from fire and water management. Genetic information is severely limited for the subspecies but could help inform decisions regarding subpopulation protections and potential translocations for genetic rescue. To provide genetic data and inform management efforts, feather samples were collected across five subpopulations (designated A–E) and protocols were tested to optimize DNA extraction yields. We assessed four mitochondrial DNA markers (N = 36–69) and 12 nuclear microsatellite loci (N = 55) in 108 sparrows. Mitochondrial DNA sequences revealed low haplotype diversity, with NADH dehydrogenase-2 haplotypes matching to most other extant subspecies and to the Atlantic coast subspecies. Nuclear diversity was low compared to other subspecies, but similar across subpopulations. Samples grouped as one population when analyzed by Principal Component Analysis, Bayesian modelling and genetic distance metrics. Limited genetic emigration was detected from one putative migrant. Relatedness was significantly different for sparrows in the most geographically distant subpopulation (A), likely reflecting high self-recruitment and natal site fidelity ( P = 0.003). The low to moderate effective population size (N E = 202.4; N E :N C = 0.06) and generation time estimates indicated that unique genetic variation could be lost quickly during stochastic events. The sample sizes were limited, which reduced the power to comprehensively address recent population size reductions and any subsequent loss of genetic diversity.

Florida

Conditions for the return and simulation of the recovery of burrowing mayflies in western Lake Erie

In the 1950s, burrowing mayflies, Hexagenia spp. ( H. limbata and H. rigida ), were virtually eliminated from the western basin of Lake Erie (a 3300 km 2 area) because of eutrophication and pollution. We develop and present a deterministic model for the recolonization of the western basin by Hexagenia to pre-1953 densities. The model was based on the logistic equation describing the population growth of Hexagenia and a presumed competitor, Chironomus (dipteran larvae). Other parameters (immigration, low oxygen, toxic sediments, competition with Chironomus, and fish predation) were then individually added to the logistic model to determine their effect at different growth rates. The logistic model alone predicts 10–41 yr for Hexagenia to recolonize western Lake Erie. Immigration reduced the recolonization time by 2–17 yr. One low-oxygen event during the first 20 yr increased recovery time by 5–17 yr. Contaminated sediments added 5–11 yr to the recolonization time. Competition with Chironomus added 8–19 yr to recovery. Fish predators added 4–47 yr to the time required for recolonization. The full model predicted 48–81 yr for Hexagenia to reach a carrying capacity of ≈350 nymphs/m 2 , or not until around the year 2038 if the model is started in 1990. The model was verified by changing model parameters to those present in 1970, beginning the model in 1970 and running it through 1990. Predicted densities overlapped almost completely with actual estimated densities of Hexagenia nymphs present in the western basin in Lake Erie in 1990. The model suggests that recovery of large aquatic ecosystems may lag substantially behind remediation efforts.

Michigan, Ohio, Ontario

No consistent effect of plant diversity on productivity

Hector et al . (1) reported on BIODEPTH, a major international experiment on the response of plant productivity to variation in the number of plant species. They found “an overall log-linear reduction of average aboveground biomass with loss of species,” leading to what the accompanying Perspective (2) described as “a rule of thumb—that each halving of diversity leads to a 10 to 20% reduction in productivity.” These conclusions, if true, imply that the continuing high rate of plant extinction threatens the future productivity of Earth's natural and managed ecosystems and could impair their ability to produce resources essential for human survival and to regulate the concentration of atmospheric CO 2 . The three sites with proper experimental design (Portugal, Sweden, and Sheffield) all showed significant positive regressions of productivity across two or three doublings of species richness [Fig. 1; (12)]. This is the pattern expected from random selection from a set of objects with different properties (13–15), because the probability of including any specific member of the set—such as a plant species that grows rapidly or fixes nitrogen—increases with the number of objects selected. Such a pattern, found consistently in randomly assembled experimental plant communities but only rarely in natural plant communities (4, 5,13–15), has been identified as a statistical artifact of experimental design (5, 13, 14). Although one study (15) suggested that the pattern constitutes a natural mechanism by which diversity affects productivity, this requires the biologically unrealistic assumption that plant communities are randomly assembled with respect to productivity (5).

Science

Effects of geolocation archival tags on reproduction and adult body mass of sooty shearwaters (Puffinus griseus)

We attached 11 g (1.4% body-mass equivalent) global location sensing (GLS) archival tag packages to tarsi of 25 breeding sooty shearwaters (Puffinus griseus, titi) on Whenua Hou (Codfish Island), New Zealand during the chick-rearing period in 2005. Compared with chicks reared by non-handled adults that did not carry tags, deployment of tags on one or both adult parents ultimately resulted in 35% reduction in chick body mass and significantly reduced chick skeletal size preceding fledging (19 April). However, body mass between chick groups was not significantly different after controlling for skeletal size. Effects on chicks were more pronounced in six pairs where both parents carried tags. Chick mass was negatively related to the duration that adults carried tags. In this study, none of the chicks reared by pairs where both parents were tagged, 54% of chicks reared by pairs where one parent was tagged, and 83% of chicks reared by non-handled and non-tagged parents achieved a previously determined pre-fledging mass threshold (564 g; Sagar & Horning 1998). Body mass of adults carrying tags and returning from transequatorial migration the following year were 4% lighter on average than non-tagged birds, but this difference was not statistically significant. Reduced mass among chicks reared by adults carrying tags during the chick-provisioning period indicated that adults altered "normal" provisioning behaviours to maintain their own body condition at the expense of their chicks. Population-level information derived from telemetry studies can reveal important habitat-linked behaviours, unique aspects of seabird foraging behaviours, and migration ecology. Information for some species (e.g., overlap with fisheries) can aid conservation and marine ecosystem management. We advise caution, however, when interpreting certain data related to adult provisioning behaviours (e.g., time spent foraging, provisioning rates, etc.). If effects on individuals are of concern, we suggest shorter-term deployments, smaller and lighter tags, and alternative attachment techniques, especially when investigating threatened or endangered species. ?? The Royal Society of New Zealand 2009.

New Zealand Journal of Ecology

Pulsed salmonfly emergence and its potential contribution to terrestrial detrital pools

Adult aquatic insects are a globally important subsidy in terrestrial food webs. However, our understanding of their importance is largely limited to studies that measure predation of live insects by terrestrial predators. Yet the flux of adult aquatic insects to terrestrial detrital pools may also be an important subsidy pathway, particularly in cases where insect production exceeds the consumption capacity of predators. We used empirical measures of giant salmonfly ( Pteronarcys californica ) emergence from 37 sites to model potential detrital deposition in nearshore riparian soil food webs. Typically, giant salmonflies emerge en masse for one week each year, and can be locally superabundant. Median detrital deposition by salmonflies ranged between 0.4 and 0.7 gC, 0.04 to 0.09 gN, and 0.002 to 0.005 gP/m 2 /yr, depending on whether 25% or 100% of available salmonflies entered detrital pools. For a small number of sites with large salmonfly populations, deposition equaled or exceeded annual secondary production of terrestrial insects, annual atmospheric N deposition, and annual atmospheric P deposition. The fact that these values rival yearly nutrient budgets is particularly striking because giant salmonfly deposition represents a subsidy from a single species emerging over a single week. The consequences of this deposition in terrestrial food webs are largely unknown, but it is likely that salmonflies can have important effects on nearshore soil nutrient budgets similar in magnitude to those of other important ecosystem processes.

Food Webs

The stability of sulfate and hydrated sulfate minerals near ambient conditions and their significance in environmental and planetary sciences

Sulfate and hydrated sulfate minerals are abundant and ubiquitous on the surface of the Earth and also on other planets and their satellites. The humidity-buffer technique has been applied to study the stability of some of these minerals at 0.1 MPa in terms of temperature-relative humidity space on the basis of hydration-dehydration reversal experiments. Updated phase relations in the binary system MgSO 4 -H 2 O are presented, as an example, to show how reliable thermodynamic data for these minerals could be obtained based on these experimental results and thermodynamic principles. This approach has been applied to sulfate and hydrated sulfate minerals of other metals, including Fe (both ferrous and ferric), Zn, Ni, Co, Cd, and Cu. Metal-sulfate salts play important roles in the cycling of metals and sulfate in terrestrial systems, and the number of phases extends well beyond the simple sulfate salts that have thus far been investigated experimentally. The oxidation of sulfide minerals, particularly pyrite, is a common process that initiates the formation of efflorescent metal-sulfate minerals. Also, the overall abundance of iron-bearing sulfate salts in nature reflects the fact that the weathering of pyrite or pyrrhotite is the ultimate source for many of these phases. Many aspects of their environmental significance are reviewed, particularly in acute effects to aquatic ecosystems related to the dissolution of sulfate salts during rain storms or snow-melt events. Hydrous Mg, Ca, and Fe sulfates were identified on Mars, with wide distribution and very large quantities at many locations, on the basis of spectroscopic observations from orbital remote sensing and surface explorations by rovers. However, many of these findings do not reveal the detailed information on the degree of hydration that is essential for rigorous interpretation of the hydrologic history of Mars. Laboratory experiments on stability fields, reactions pathways, and reaction rates of hydrous sulfates likely to be found on Mars enhance our understanding of the degrees of hydration of various sulfates that should currently exist on Mars at various seasons and locations and during various atmospheric pressure and obliquity periods. Two sets of systematic experiments were described; one on hydrous Mg sulfates and the other on hydrous Fe 3+ sulfates. Also, their implications to Mars sulfates mineralogy were discussed.

Journal of Asian Earth Sciences

Decision analysis for greater insights into the development and evaluation of Chinook salmon restoration strategies in California’s Central Valley

Considerable amounts of resources have been invested in ecological restoration projects across the globe to restore ecosystem integrity. Restoration strategies are often diverse and have been met with mixed success. In this paper, we describe the Chinook salmon (Oncorhynchus tshawytscha) decision-support models developed by the Central Valley Project Improvement Act Science Integration Team as part of a larger structured decision making effort aimed at maximizing natural adult production of Chinook salmon in California’s Central Valley, USA. We then describe the decision analytic tools the stakeholder group used to solve the models and explore model results, including stochastic dynamic programming, forward simulation, proportional scoring, relative loss, expected value of perfect information, response profile analyses, and indifference curves. Using these tools, the stakeholder group was able to develop and evaluate restoration strategies for multiple Chinook salmon runs simultaneously, a first for the restoration program. We found that actions targeted at one run were detrimental to others, which was unexpected. Furthermore, information uncovered during this process was used to direct efforts towards targeted research/monitoring to reduce critical uncertainties in salmon demographic rates and make better restoration decisions moving forward. The decision sciences have established a wide range of analytical tools and approaches to simplify complex problems into key components, and we believe the concepts described in this paper are of great interest and can be applied by many restoration practitioners that undoubtedly face similar difficulties when implementing restoration strategies for complex systems.

California

Geologic resource evaluation of Kaloko-Honokohau National Historical Park, Hawai'i: Geology and coastal landforms

Geologic resource inventories of lands managed by the National Park Service (NPS) are important products for the parks and are designed to provide scientific information to better manage park resources. Park-specific geologic reports are used to identify geologic features and processes that are relevant to park ecosystems, evaluate the impact of human activities on geologic features and processes, identify geologic research and monitoring needs, and enhance opportunities for education and interpretation. These geologic reports are planned to provide a brief geologic history of the park and address specific geologic issues that link the park geology and the resource manager. The Kona coast National Parks of the Island of Hawai'i are intended to preserve the natural beauty of the Kona coast and protect significant ancient structures and artifacts of the native Hawaiians. Pu'ukohola Heiau National Historic Site (PUHE), Kaloko-Honokohau National Historical Park (KAHO), and Pu'uhonua O Honaunau National Historical Park (PUHO) are three Kona parks studied by the U.S. Geological Survey (USGS) Coastal and Marine Geology Team in cooperation with the National Park Service. This report is one of six related reports designed to provide geologic and benthic-habitat information for the three Kona parks. Each geology and coastal-landform report describes the regional geologic setting of the Hawaiian Islands, gives a general description of the geology of the Kona coast, and presents the geologic setting and issues for one of the parks. The related benthic-habitat mapping reports discuss the marine data and habitat classification scheme, and present results of the mapping program. Kaloko-Honokohau National Historical Park (KAHO) was established in 1978 in order to preserve and protect traditional native Hawaiian culture and cultural sites. The park is the site of an ancient Hawaiian settlement, occupies 469 ha and is considered a locale of considerable cultural and historical significance. Cultural resources include fishponds, petroglyphs and a heiau (religious site). The fishponds are also recognized as exceptional birding areas and are important wetlands for migratory birds. The ocean and reef have been designated as a Marine Area Reserve, where green sea turtles commonly come ashore to rest. The park is also a valuable recreational resource, with approximately 4 km of coastline and a protective cove ideal for snorkeling and swimming. KAHO park boundaries extend beyond the mean high tide line and include the adjacent marine environment. An accompanying report for KAHO presents the results of benthic habitat mapping of the offshore waters, from the shoreline to approximately 40 m water depth. Ground-water quality and potential downslope impacts created by development around the park are of concern to Park management.

Hawaii

Endocrine disrupting chemicals in Minnesota lakes - Water-quality and hydrological data from 2008 and 2010

Understanding the sources, fate, and effects of endocrine disrupting chemicals in aquatic ecosystems is important for water-resource management. This study was conducted during 2008 and 2010 to establish a framework for assessing endocrine disrupting chemicals, and involved a statewide survey of their occurrence in 14 Minnesota lakes and a targeted study of different microhabitats on a single lake. The lakes ranged in size from about 0.1 to 100 square kilometers, varied in trophic status from oligotrophic to eutrophic, and spanned a range of land-uses from wetlands and forest to agricultural and urban use. Water and sediment samples were collected from the near-shore littoral environment and analyzed for endocrine disrupting chemicals, including trace elements, acidic organic compounds, neutral organic compounds, and steroidal hormones. In addition, polar organic compound integrative samplers were deployed for 21 days and analyzed for the same organic compounds. One lake was selected for a detailed microhabitat study of multiple near-shore environments. This report compiles the results from the field measurements and laboratory chemical analysis of water, sediment, and polar organic compound integrative sampler samples collected during 2008 and 2010. Most of the organic compounds measured were not detected in any of the water samples, although a few compounds were detected in several of the lakes.

Minnesota

Proceedings of the fourth conference on research in California's National Parks

The papers in this proceedings were selected from the 63 presentations given at the Fourth Biennial Conference on Research in National Parks in California. The overall theme for this meeting was a recurring one: “The Integration of Research into National Park Service Resource Management Decisions.” The conference was held at the University of California, Davis, on 10-12 September 1991 and was sponsored by the National Park Service Cooperative Park Studies Unit and the Institute of Ecology at the University of California, Davis. This proceedings highlights a variety of research and resource management efforts to improve the stewardship of our most treasured landscapes. In the future, it will become increasingly more important for federal and state agencies, university scientists and students, and the public to cooperate fully to improve the quantity and quality of science and resource management programs in units of the National Park System. As many of the papers in this proceedings attest, we must look beyond the political boundaries of protected landscapes to incorporate entire ecosystems. Competing resource uses inside and outside parklands must be reexamined to weave a common thread of biological conservation. As scientists, our studies must bridge the gap from plots to landscapes and from landscapes to regions. Our studies must built on information from species and populations to ecosystems and the processes that influence them. The papers in this proceedings are modest but important contribution to those ideals. Each paper represents original research and has been peer-reviewed. Many agencies, institutions, and individuals contributed in the development of this product. In the planning stages, National Park Service Western Region scientists provided advice and assistance in structuring the conference format. University of California, Davis, graduate students, directed by Sharon Lynch, assisted with logistics at the meeting, and provided general assistance with the paper sessions. We thank the students, technicians, and support staff who labored unselfishly behind the scenes to collect data and transfer information important to the completion of each paper. Financial support for this publication was provided with funds from the Western Region Resource Management and Resource Program and the Washington Office Servicewide Publications Program of the National Park Service. We thank Denny Fenn, Stan Albright, Bruce Kilgore, Dave Cherry, Gene Hester, and Donna O'Leary of the National Park Service and Charles Goldman of the University of California, Davis, Institute of Ecology for their support throughout the development of the proceedings. Finally, we are entering into a new age of research in the U.S. Department of the Interior. Recently, plans were announced for the creation of the National Biological Survey, dedicated to improving the quantity and quality of research necessary for the wise stewardship of our natural resources and wildlands. We welcome our new partners and pledge our full support to both the new and old agencies. The papers presented here--and past research efforts in national parks--provide an important stepping stone to the future. While many of us will be transferred administratively to the National Biological Survey, our emotional ties to the National Park Service mission of preserving resources for future generations will remain with us forever.

California

Integration of MODIS-derived metrics to assess interannual variability in snowpack, lake ice, and NDVI in southwest Alaska

Impacts of global climate change are expected to result in greater variation in the seasonality of snowpack, lake ice, and vegetation dynamics in southwest Alaska. All have wide-reaching physical and biological ecosystem effects in the region. We used Moderate Resolution Imaging Spectroradiometer (MODIS) calibrated radiance, snow cover extent, and vegetation index products for interpreting interannual variation in the duration and extent of snowpack, lake ice, and vegetation dynamics for southwest Alaska. The approach integrates multiple seasonal metrics across large ecological regions. Throughout the observation period (2001-2007), snow cover duration was stable within ecoregions, with variable start and end dates. The start of the lake ice season lagged the snow season by 2 to 3??months. Within a given lake, freeze-up dates varied in timing and duration, while break-up dates were more consistent. Vegetation phenology varied less than snow and ice metrics, with start-of-season dates comparatively consistent across years. The start of growing season and snow melt were related to one another as they are both temperature dependent. Higher than average temperatures during the El Ni??o winter of 2002-2003 were expressed in anomalous ice and snow season patterns. We are developing a consistent, MODIS-based dataset that will be used to monitor temporal trends of each of these seasonal metrics and to map areas of change for the study area.

Remote Sensing of Environment

Geology and vertebrate paleontology of Tule Springs Fossil Beds National Monument, Nevada, USA

Tule Springs Fossil Beds National Monument (TUSK) preserves 22,650 acres of the upper Las Vegas Wash in the northern Las Vegas Valley, Nevada, USA. TUSK is home to extensive and stratigraphically complex groundwater discharge (GWD) deposits, called the Las Vegas Formation, which represent springs and desert wetlands that covered much of the valley during the late Quaternary. The GWD deposits record hydrologic changes that occurred here in a dynamic and temporally congruent response to abrupt climatic oscillations over the last ~300 ka (thousands of years). The deposits also entomb the Tule Springs Local Fauna (TSLF), one of the most significant late Pleistocene (Rancholabrean) vertebrate assemblages in the American Southwest. The TSLF is both prolific and diverse, and includes a large mammal assemblage dominated by Mammuthus columbi and Camelops hesternus. Two and possibly three distinct species of Equus, two species of Bison, Panthera atrox, Smilodon fatalis, Canis dirus, Megalonyx jeffersonii, and Nothrotheriops shastensis are also present, and newly recognized faunal components include micromammals, amphibians, snakes, and birds. Invertebrates, plant macrofossils, and pollen also occur in the deposits and provide important and complementary paleoenvironmental information. This field compendium highlights some of the classic stratigraphic sequences of the Las Vegas Formation within TUSK, emphasizes the significant hydrologic changes that occurred in the area during the recent geologic past, and examines the subsequent and repeated effect of rapid climate change on the local desert wetland ecosystem.

Nevada

Water-quality assessment of the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia; organochlorine compounds in Asiatic clam (Corbicula fluminea) soft tissues and whole redbrest sunfish (Lepomis auritus) 1992-93

The analysis of potential contaminants in biological tissues is an important part of many water-quality assessment programs, including the National Water-Quality Assessment (NAWQA) Program. Tissue analyses often are used to provide information about (1) direct threats to ecosystem integrity, and (2) the occurrence and distribution of potential contaminants in the environment. During 1992-93, Asiatic clam (Corbicula fluminea) soft tissues and whole redbreast sunfish (Lepomis auritus) samples were collected and analyzed to obtain information about the occurrence and distribution of organochlorine compounds in the Albemarle-Pamlico drainage Basin of North Carolina and Virginia. The investigation was conducted as part of the NAWQA Program. Relatively few organochlorine compounds were detected and of the compounds detected, all were detected in relatively low concentrations. The organochlorine compounds detected were p,p'-DDD, p,p'-DDE, p,p'-DDT, dieldrin, trans-nonachlor, PCB's, and toxaphene. Multiple compounds were detected at 16 of 19 sites sampled. Compared to Asiatic clams, redbreast sunfish appear to be better bioindicators of organochlorine contamination in aquatic systems. Except for one detection of toxaphene, pesticide concentrations are well below the National Academy of Sciences and National Academy of Engineering (NAS/NAE) guidelines for the protection of fish-eating wildlife.

North Carolina, Virginia

Facing a changing world: Thermal physiology of American pikas ( Ochotona princeps )

American pikas ( Ochotona princeps ) are of concern with respect to warming montane temperatures; however, little information exists regarding their physiological ability to adapt to warming temperatures. Previous studies have shown that pikas have high metabolism and low thermal conductance, which allow survival during cold winters. It has been hypothesized that these characteristics may be detrimental, given the recent warming trends observed in montane ecosystems. We examined resting metabolic rate, surface activity, and den and ambient temperatures (T a ) of pikas in late summer (August 2011 and 2012) at 2 locations in the Rocky Mountains. Resting metabolic rate was calculated to be 2.02 mL O 2 · g -1 h -1 , with a lower critical temperature (LCT) of 28.1 ± 0.2 °C. No upper critical temperature (UCT) could be determined from our data; therefore, the estimated thermoneutral zone (TNZ) was 28.1 °C to at least 35.0 °C (upper experimental temperature). Pikas in this study showed the same bimodal above-talus activity patterns reported in previous studies. Den temperatures in Colorado were correlated with, but consistently lower than, current ambient temperatures. Wyoming den temperatures showed a weak correlation with T a 20 min prior to the current den temperature. This study is one of few to present data on the physiological response pikas may have to current warming conditions, and the first to perform metabolic measurements in situ. Our data support conclusions of previous studies, specifically MacArthur and Wang ( 1973 , 1974 ) and Smith ( 1974 ), which indicated American pikas may not have the physiological ability to cope with high Ta. Our results also highlight the importance of shaded regions below the talus rocks for behavioral thermoregulation by pikas.

Western North American Naturalist