Archives -- Research Reports

1997-1998 RESEARCH REPORTS

Aquatic Biology and Chemistry
Terrestrial Botany

Aquatic Biology and Chemistry

The Effects of Spatial Heterogeneity in Light and Nutrients on Trophic Interactions in Streams 
Scott D. Cooper, Department of Ecology, Evolution, and Marine Biology, UCSB
Over the last several years, my research group and I have conducted field experiments, and laboratory and computer analyses, dealing with the effects of consumers on the abundances and spatial heterogeneity of stream organisms. Complementing this work, we have recently begun to focus on the effects of spatial heterogeneity in forcing functions (e.g., light, nutrients, depth, current speed) on the distributions, abundances, productivity, and movements of stream organisms. In early summer, 1998, we mapped the spatial distributions of values of abiotic (e.g., light intensity, depth) factors in SNARL streams. This information will guide the design of experiments examining the effects of levels and spatial heterogeneity in physical and chemical factors on stream communities and ecosystem processes. Funding: National Science Foundation.

Evaluation of Rangeland Stream Condition and Recovery Using Physical and Biological Assessments of Nonpoint Source Pollution
David B. Herbst, SNARL and Marine Science Institute, UCSB
The specific aim of this project is to provide a biological basis for establishing standards and regulatory criteria for nonpoint source pollution impacts related to livestock grazing in rangeland stream ecosystems. Bioassessment is a technique that uses aquatic insects and other invertebrates as indicators of pollution. Using differences in pollution tolerance and functional roles in the ecosystem, changes in the types of organisms found can be used to monitor the extent of impacts and/or habitat recovery. In order to apply the technology of bioassessment to grazing, this study will develop (1) reference stream standards, (2) a baseline for trend comparisons in invertebrate communities exposed to varied grazing management practices, and (3) a database on sediment-polluted streams that can be used to analyze invertebrate associations and establish a tolerance scoring system for indicator fauna specific to grazing-related impacts. The approach of the research supported by this grant has been to apply the technique of bioassessment to identify grazing pollution problems and compare this system with traditional monitoring methods that have relied on such stream features as channel geomorphology and riparian vegetation. Results from the first year and a half of studies are based on (1) a pilot project comparing seasonal differences in physical habitat conditions, aquatic invertebrate communities, and fish populations among nine stream reaches including a single ungrazed reference reach, and (2) an expanded study designed to (i) establish multiple reference stream reaches, (ii) initiate a set of sites for baseline trend monitoring, and (iii) obtain a data set from varied habitat conditions to be used for developing invertebrate indicator groups of pollution related to grazing impacts. Results suggest that bioassessment may detect short-term and local grazing impacts, but that single-season bioassessment measures are inadequate to capture the range of variation. The initial project phase has revealed differences between an ungrazed site and polluted grazed sites, and permitted contrasts and derivation of monitoring indicators, but also has limitations due to low sample sizes and redundant measures. Sampling was expanded during the summers of 1996-97 (July-September) with samples taken from 82 stream reaches to date. Detailed taxonomic analysis of the samples includes identification of midges (chironomidae), a group often ignored in bioassessment but found here to have nearly the same amount of taxonomic diversity as all other invertebrate groups combined. This will add greater predictive power to indicator group analysis. Funding: Environmental Protection Agency.

Aquatic Habitat Formed on Owens Dry Lake by Flood Irrigation: Renewal of a Biological Community in Seasonal Habitats
David B. Herbst, SNARL and Marine Science Institute, UCSB 
Dean W. Blinn, Department of Biological Sciences, Northern Arizona University
Since Owens Lake dried over 60 years ago, alkali dust storms originating from the dry playa have become persistent in the Owens Valley. Among the more promising solutions to eliminating dust storms has been to temporarily flood playa dust source areas during the windy seasons. This not only reduces dust, but creates renewed aquatic habitat inhabited by many of the same creatures previously found in Owens Lake. In seeps and springs along the playa margins are refuge habitats that sustain populations of the flora and fauna (algae and invertebrates) that once lived in the lake. These organisms recolonize the habitat rapidly when opportunities arise. This project provides information on the biological diversity and productivity of flooded aquatic habitat (natural and irrigated) and the water quality conditions most favorable for the renewal of food resources for migratory and breeding shorebirds and waterfowl. Algae and invertebrates form the base of the food chain for foraging water birds. Observations of ephemeral flood waters forming on the playa suggest that they are rapidly colonized from marginal spring and seep habitat refugia and become foraging sites previously unavailable to migratory shorebirds. Surveys of habitat refugia and natural flood zones around the margins of Owens Lake playa showed that at least 70 species of aquatic invertebrates were present. Experimental studies of salinity effects on biological communities were conducted using field microcosms (50 liter tanks embedded in playa sediments) within which salinity and evaporation rate were controlled. Limitation of the productivity of saline aquatic habitat by biological factors at low salinity and physiological stress at high salinity support a model for the ecology of salt lakes known as the intermediate salinity hypothesis. Laboratory studies of the development of E. hians further support this interpretation by showing that in the absence of competition or predation, survival and development of this insect are most favorable at the lowest salinities. Funding: Great Basin Air Pollution Control District.

Survey of Invertebrate Communities in Spring Habitats on the Ruby Lake National Wildlife Refuge, Elko and White Pine Counties, Nevada 
David B. Herbst, SNARL and Marine Science Institute, UCSB
Spring habitats in the Great Basin have been developed to varying extents for livestock access, irrigation, waterfowl habitat, and consumptive uses. These are sensitive and geographically isolated habitats often harboring rare and endemic species. Fifty springs were surveyed in the late spring and late summer of 1997. Invertebrate communities were sampled using a D-frame kick/sweep net in the spring source and at 50 meters downstream in the outflow springbrook channel. Refuge management has included the dredging of spring sources and channels to enhance habitat for waterfowl through the formation of pond and canal systems. Springs were selected for comparing the impacts of historical dredging at the source or the channel, or both, to a set of interspersed reference springs without dredging impacts (and minimal grazing impacts). Substrates, flows, submerged vegetation and other habitat features were measured at each sample site where invertebrates were collected. Riparian vegetation communities were also characterized along the length of the study springs. Samples are presently being processed to assess the community structure of invertebrates. Statistical comparisons will be made between the treatment groups using multivariate techniques to distinguish assemblage types. Indicator organisms will also be identified as management priorities. For example, a new species of blind, cave-dwelling amphipod was collected during this study (Stygobromus n. sp.) that is associated only with unimpacted rocky spring sources. Few comparative studies of Great Basin spring communities and their alterations have been conducted. This study will provide valuable insights into how development alters spring communities, and practical information on habitat protection priorities and biological baselines for restoration and management. Funding: U.S. Fish and Wildlife Service.

Leviathan Mine Bioassessment 
David B. Herbst, SNARL and Marine Science Institute, UCSB
Soil erosion and acid mine drainage (AMD) from adits and seeps at the abandoned Leviathan Mine create a chronic source of water pollution in the watershed of Bryant and Leviathan Creeks. These streams, north of Monitor Pass in California's Sierra Nevada, have been exposed to AMD for over 40 years, and show little if any indication of recovery. Low (acidic) pH, elevated trace element concentrations, and deposits of iron and aluminum hydroxides (commonly called yellow-boy precipitate) continue to contaminate water bodies within this watershed. In an effort to establish biological criteria for monitoring stream health, benthic (bottom-dwelling) invertebrates were collected from a gradient of sites below Leviathan Mine in 1995 and 1997. With pollution mitigation projects both underway and planned for the former open-pit mine site (now owned by the State of California), these data provide a benchmark for evaluating the existing ecological conditions and the progress and success of mine clean-up efforts. The purposes of the studies reported here are to establish baseline data for continued biomonitoring that will: (1) delineate the amount of stream habitat currently degraded by AMD, and (2) provide a baseline for future comparisons of water quality. The monitoring approach taken here is based on macroinvertebrate bioassessment, which uses measures of the structure of aquatic invertebrate communities as indicators of the ecological health and integrity of stream ecosystems. Collections in 1995 and 1997 were taken at six sites within the watershed including unimpacted references and a gradient of reaches at increasing distances downstream of the mine drainage source. In conjunction with biological sampling, sediment contamination and other physical and chemical features were also measured at each site. At sites on Leviathan Creek, and the upper portions of Bryant Creek, contamination by yellow-boy precipitate was extensive and sediments contained higher concentrations of trace elements (including aluminum, arsenic, chromium, cobalt, copper, iron, nickel, selenium, thallium, and zinc) than on the reference sites not exposed to AMD. These locations also showed moderate to severe ecological impacts in the form of reductions in the abundance and diversity of aquatic invertebrates, leaving only a depauperate fauna of relatively pollution-tolerant organisms. On the lower portion of Bryant Creek (about 13 km below the mine), some biological recovery was apparent, but this location still did not achieve levels of diversity or abundance found on the reference site (the unimpacted Mountaineer Creek drainage). Data from both 1995 and 1997 show the same patterns, although diversity was higher at all sites in 1997. Documenting this natural variability is an important aspect of separating annual and seasonal variation from effects of the impact of AMD. These studies localize the area and extent to which stream reaches in this watershed are impacted by AMD and provide a target for ecological recovery from the effects of AMD pollution. Habitat and biological conditions are most degraded immediately below the mine and up to 6 to 13 km downstream, where the biota begin to recover. Funding: Lahontan Regional Water Quality Control Board.

Exotic Eradication on Ecosystem Structure and Function 
Roland Knapp, SNARL and Marine Science Institute, UCSB 
Orlando Sarnelle, Marine Science Institute, UCSB and Michigan State University
Exotic species have had large impacts on ecosystems worldwide, causing extinctions of native species and large alterations in species composition and ecosystem processes. Despite long-standing interest in exotic effects, quantitative studies of ecosystem recovery after the eradication of exotics are rare. Study of exotic eradication provides a rare opportunity to study the fundamental ecological process of community assembly in nature. Such study is essential to determine whether natural communities converge on a single configuration after perturbation. Community convergence has important implications for the conservation of biodiversity. This project examines the recovery of alpine lake systems in the Sierra Nevada after the eradication of exotic trout. Our first major objective asks whether the species composition of alpine lakes re-assembles to its pristine state after release from exotic perturbation. We are eradicating exotic trout from three lakes and comparing them to three lakes in which trout stocking will continue. We are particularly interested in how the recovery times of species that are currently extinct varies with the life history traits of these species. We will compare experimental results with an extensive survey of Sierran lakes that vary in both the duration of trout presence and in the length of time since exotic trout have died out. Our second objective examines how basic ecosystem processes respond during the recovery of experimental lakes from exotic trout removal. The goal here will be to determine how changes in species composition and biodiversity alter the relative contributions of benthic and pelagic photosynthesis to lake-wide primary production. Funding: National Science Foundation.

Introduced Trout in the Sierra Nevada, California: Effects on Native Aquatic Species 
Roland A. Knapp, SNARL and Marine Science Institute, UCSB
This project is designed to elucidate the impacts of non-native trout on lake ecosystems in the Sierra Nevada. Historically, nearly all Sierran lakes were fishless. Starting in the 1850's and continuing to the present day, however, trout have been stocked in nearly all suitable waters. Because trout are highly-effective predators, these introductions have resulted in precipitous declines in species adapted to fishless lakes, including amphibians, zooplankton, and benthic invertebrates. In some cases (e.g., amphibians), these declines have been severe enough that some species may soon be listed under the Endangered Species Act. In order to better understand the impacts of introduced trout on lake ecosystems, we sampled approximately 2,200 lakes and ponds over a 1,500 km2 landscape in Kings Canyon National Park and the John Muir Wilderness for fish, amphibians, zooplankton, and benthic invertebrates. The sampling design we used allowed us to separate the effects of fish from global environmental changes that may influence the distribution of aquatic species. Our results indicate that trout introductions are primarily responsible for the near-extirpation of the mountain yellow-legged frog from much of its historic range. In addition, the introduction of trout has caused extensive alteration of zooplankton and benthic invertebrate communities, whereby large-bodied, conspicuous species have been replaced by small-bodied, inconspicuous species. Unlike the mountain yellow-legged frog, however, the invertebrate species sensitive to trout presence are still relatively common across the landscape owing to their ability to persist in small, fishless ponds. This information is now being used to design a series of reserves to maintain and restore viable populations of sensitive native species, especially the mountain yellow-legged frog. As such, our study will have important consequences for the future management of high mountain lake ecosystems. Funding Sources: U.S. Forest Service.

Vertical Mixing Across a Nutricline Supplies Nutrients to Phytoplankton 
Sally MacIntyre, Marine Science Institute, UCSB
This study in Mono Lake in 1997 and 1998 was designed to determine the flux of nutrients into and within the euphotic zone due to boundary mixing and upwelling. To this end, we coupled measurements of turbulence with profiles of nutrient concentration. In addition, we obtained time series data on meteorology and thermal structure. These combined data allow prediction of the intensity of surface forcing required to initiate mixing events in the pycnocline. In addition, in 1998, Jordan Clark injected a tracer, sulfur hexafluoride, just above the top of the pycnocline. His data, combined with our turbulent microstructure profiles and lake-wide CTD profiles, allow inter-comparisons of three independent methods for estimating the coefficient of eddy diffusivity, a key term for calculating nutrient fluxes in stratified lakes. Results from the 1997 experiment were presented at the 1998 Ocean Sciences Meeting. Vertical mixing also influences the supply of light to phytoplankton. G. Johnson sampled the vertical distribution of phytoplankton in the surface layer of Mono Lake as part of her studies of photoadaption of phytoplankton. N. Scully measured the distribution of hydrogen peroxide in Convict Lake. H2O2 is photochemically produced in the surface waters of lakes. Its distribution with depth depends on penetration of ultraviolet radiation, the presence of dissolved organic carbon, and vertical mixing. Estimates of the coefficient of eddy diffusivity obtained using measurements of ultraviolet radiation and H2O2 with those obtained with microstructure profiling were similar, indicating that both procedures are appropriate for calculating the light history of phytoplankton. Funding: National Science Foundation.

Monitoring of Limnology and Plankton in Mono Lake 
John M. Melack, Department of Ecology, Evolution, and Marine Biology and Marine Science Institute, UCSB Robert Jellison, SNARL and Marine Science Institute, UCSB
Mono Lake is a large, hypersaline, highly productive alkaline lake lying just east of the Sierra Nevada. In addition to its recreational, scenic, and water resource values, it contains large populations of an endemic brine shrimp and the alkali fly which are important food sources for migrating birds. Although saline lakes are common throughout the world and provide important ecological resources for many species, they are much less studied than freshwater ecosystems. Limnological monitoring conducted from 1979-1998 represents one of the longest continuous studies of any hypersaline ecosystem and, in addition to addressing current environmental concerns in the Mono Basin, provides insight into the functioning of saline ecosystems. Funding: Los Angeles Department of Water and Power.

Responses of a Saline Lake to Environmental Change 
John M. Melack, Department of Ecology, Evolution, and Marine Biology and Marine Science Institute, UCSB Robert Jellison, SNARL and Marine Science Institute, UCSB
Saline lakes constitute nearly half of inland waters by volume and provide ecologically important aquatic habitats in arid regions of the world. They often have high rates of algal productivity which support aquatic invertebrates and large numbers of birds. At Mono Lake, California environmental concern has focused on the impacts of higher salinity caused by the diversion of freshwater streams that used to flow into Mono Lake. In 1994, state agencies decided to gradually raise the surface elevation of Mono Lake to approximately six meters above the historic low in 1982. This action provides a unique opportunity to study the effects of environmental change on a large saline lake. Ecological studies of the lake's biota during the period of rising lake levels and decreasing salinity will complement prior laboratory studies focused on the effect of increased salinity on Mono Lake's biota. Funding: National Science Foundation.

Effects of Flow and Population Density on the Movement of Brown Trout in Artificial Stream Channels
J. Emil Morhardt, Roberts Environmental Center, Claremont McKenna College
1) Feasibility of using large Passive Integrated Transponder (PIT) tags to locate and monitor movements of trout in streams. This study evaluated a field reading system for passive integrated transponder (PIT) tags measuring 4 x 23 mm and 4 x 32 mm operating at a frequency of 134.2 kHz. The system utilizes a combination of a commercial electronic energizer-reader module and either a small (22 x 140 mm) cylindrical ferrite-stick antenna or a 270 x 720 x 15 mm flat-loop antenna "in configurations certified by the Federal Communications Commission" combined with a custom interface to a hand-held calculator which is used as the readout and data storage unit. The stick antenna was mounted in a hand-held probe. Maximum tag read distances were between 33 and 45 cm for the stick antenna and between 34 and 85 cm for the loop antenna, depending on the size of the tag and its orientation to the antennae. The range of the stick antenna was similar in air and water, whether near substrate or not, and whether or not behind large cobbles in the water. We tested the loop antenna only in water. We tested the system using wild brown trout (Salmo trutta) and wild rainbow trout (Oncorhyncus mykiss) with tags attached both externally near the dorsal fin and inserted into the peritoneal cavity with a hypodermic needle. The fish were held in artificial outdoor stream channels (1 m x 50 m, up to 0.5 m deep), in a stream section bounded at either end by dams (3-4 m wide, 70 m long, 0.2-0.80 m deep), and in a similar 90 m section of stream bounded only at the downstream end. Although we did not conduct a formal study of the long-term suitability of either type of tag placement or of the overall efficiency of this system in detecting marked fish, we were routinely able to detect marked fish both by walking along the channels and stream section with a hand-held probe and by positioning the antenna on the substrate and recording tags from undisturbed fish as they swam by. 2) Stream-dwelling salmonids, when feeding on drifting insects, can be repeatedly observed at specific locations, often referred to as focal points. There is considerable evidence that it is the hydraulic features of focal points that determine fish locations and that such positions allow fish to minimize their energy expenditures while maximizing the probability of capturing food. By snorkeling, we observed several types of focal points used by brown trout in a natural stream channel, including stream bottom depressions and protuberances, and areas of slow water beside much faster water. Using a Doppler velocity meter capable of measuring all three flow velocity components within a sampling volume 3-9 mm long and approximately 6 mm in diameter 5 cm away from the probe head, we mapped the velocity structure in the vicinity of several focal points. Funding: Self-funded.

Coexistence of the Mountain Yellow-legged Frog (Rana muscosa) and Introduced Trout in Sequoia and King's Canyon National Parks 
Vance T. Vredenburg, Department of Integrative Biology, UC Berkeley
Mountain yellow-legged frogs (Rana muscosa) were once very common throughout the high elevation aquatic ecosystems of the Sierra Nevada in California, but have declined dramatically in recent years. Although increases in UV-B radiation and pesticide drift have been proposed as important contributing factors, much of this decline has been attributed to predation by introduced trout. At present, the distribution of introduced trout and the remaining populations of Rana muscosa are strongly allotopic, yet there are a few cases where tadpoles, adult frogs, and trout have been reported to coexist in the same habitat. I surveyed 83 lakes and ponds in a basin having many reports of coexistence and found only eight lakes with both trout and Rana muscosa. Tadpole numbers were significantly higher in lakes that did not contain trout. Of the eight lakes with frogs and fish, only one had large numbers of frog larvae, and it had only a few trout and no trout reproduction. As a result of this work, I suggest that there is little if any stable co-existence between Rana muscosa and introduced trout; apparent cases probably result from transient movements of adults and subadults, or represent sink populations. The significance of these results are important to the conservation of Rana muscosa in the Sierra Nevada, and suggest that introduced trout may be one of the most important factors controlling Rana muscosa distributions. Funding: 1997 Gompertz Award, Museum of Vertebrate Zoology, UC Berkeley.

Helium Isotopes in Mono Lake 
Jordan Clark, Department of Geological Sciences, UCSB
Concentrations of He-3 and He-4 in Mono Lake are greater than atmospheric equilibrium values indicating a subsurface source of helium. This assertion is supported by vertical concentration profiles which show that maximum delta-He-3 values (+70%) occur immediately below the pycnocline. The slope of the correlation between He-3 and He-4 concentrations is about 3.2 Ra (Ra = atmospheric helium isotope ratio) indicating that the subsurface source has a component of mantle helium. Helium isotope ratios of spring water collected near the lake range between 1.6 and 5.6 Ra. The most similar ratio, 2.7 Ra, was found in hydrothermal springs and gas vents from Pahoa Island which is located in the middle of Mono Lake suggesting that springs from this island contribute the majority of the subsurface helium. A helium mass balance suggests that the maximum influx of hydrothermal water into Mono Lake is 1.6 x 106 m3/yr. This is equivalent to approximately a 1 cm rise in lake level each year and is less than 1% of the annual evaporation rate. This estimate of the hydrothermal water flux is a maximum value because helium may also be injected into Mono Lake by the subsurface dissolution of gas bubbles emanating from submerged gas vents. Funding: Department funds.

Spatial and Temporal Distributions of Snow Processes and Surface Energy Exchange in Alpine and Subalpine Environments 
Robert E. Davis, Geophysical Sciences Division, Cold Regions Research and Engineering Laboratory (CRREL)
This research seeks to improve understanding of the spatial and temporal distributions of snow processes and surface energy exchange in alpine and subalpine environments by comparing model predictions of snow properties with field measurements and map-based products from remote sensing. Our research will improve the CRREL snow model SNTHERM, test new techniques for measuring snow properties, and develop methods to use terrain and land cover data to spatially distribute SNTHERM. Our experiments ranged in spatial and temporal scales from detailed physics studies at the cooperative Mammoth Mountain snow study plot over periods of a few days, to parameterized experiments over areas up to a few square kilometers lasting several weeks. This last winter we upgraded the instrumentation at the study plot to increase the number of variables we measure for model validation. Our computers automatically downloaded a wide variety of measurements daily for processing into model input and testing formats. We will use these data to assess new formulations of turbulent transfer of latent and sensible heat exchange currently under development at the Cold Regions Research and Engineering Laboratory. We will soon complete development of a new terrain and vegetation cover data base of the Mammoth Mountain area, which will support spatially distributed modeling of snow processes in the alpine and subalpine zones. Comparison of model predictions with products from satellite and aircraft measurements will improve development of methods to segment land cover and terrain data sets, as well as our ability to specify initial conditions for model experiments. The winter and spring of 1996-1997 marked the third year of detailed measurements of snow depth, water equivalence and extent on the mountain side above the study plot. Preliminary results showed that the spatial patterns of snow extent during ablation appear similar despite different amounts of total accumulation during the three years. This experiment will lead to improved parameterization of model processes below the spatial resolution of model response units. Funding: U.S. Army Corps of Engineers; Institute for Computational Earth System Science (ICESS), UCSB.

Hydrology, Hydrochemical Modeling, and Remote Sensing in Seasonally Snow-covered Alpine Drainage Basins 
Jeff Dozier, Donald Bren School of Environmental Science and Management, UCSB
Roger Bales, Hydrology and Water Resources Department, University of Arizona 
John Melack, Institute for Computational Earth System Science and Department of Ecology, Evolution, and Marine Biology, UCSB 
Kathy Tonnessen, National Park Service, National Biological Service 
Mark Williams, University of Colorado
This project continues a decade long research investigation of alpine regions. Mountainous areas, particularly in the western U.S., supply a large fraction of freshwater resources through snowmelt, and are especially sensitive to changes in climate and precipitation chemistry. Knowledge of the hydrologic cycle in alpine areas of seasonal snow and glaciers is limited by incomplete understanding of the processes that determine the cycle. Research for this investigation combines three methods to try to further understand these processes: observation in the field and laboratory; measurements from remote sensing; and models of hydrologic processes and chemical transformations. Our modeling results are helping to couple basin-wide energy-balance snowmelt models with remote sensing and flow routing. Our remote sensing work now allows us to estimate important hydrologic variables from space or aircraft. Our studies of global hydrology and hydrochemistry result in an accumulation of massive amounts of scientific data. We are addressing the need to manage these large, complex data sets. Systems, including relational and object-relational databases, are in place for managing data and metadata pertaining to field measurements, imagery, and inter-system C and N fluxes. Funding: NASA.

Carbon Dioxide Emissions in the Mammoth Lakes Area 
Chris Farrar, U.S. Geological Survey, Carnelian Bay, California
Research on the carbon dioxide emissions in the Mammoth Lakes areas is part of the U. S. Geological Survey Volcanic Hazards Program. SNARL served as a base for the research aimed at identifying, quantifying, and mapping areas of anomalously high CO2 concentrations in soil gas. Surveys have focused in a ring around Mammoth Mountain where coniferous forest has been killed by excessive gas concentration (up to 95% vol.). Analysis of high resolution airborne multispectral images is being done to help focus ground-based carbon dioxide flux measurements. The source of CO2 is either directly from degassing magma or from carbonate rocks heated by magma. Funding: U.S. Geological Survey.

Hydrology of the Sierra Nevada 
Richard Kattelmann, Institute of Computational Earth System Science and SNARL, UCSB
I continued snowpack studies at Mammoth Mountain and other sites in the Sierra Nevada with UCSB's NASA-sponsored Earth Observing System project. The extended winter this year provided an opportunity to study an unusually deep snowpack in late spring and summer. Some progress was made on various flood studies in mountain areas. Collaborative work with the U.S. Army's Cold Regions Research and Engineering Lab continued at the snow research site at Mammoth Mountain. I also participated in an effort of the State Water Resources Control Board and Mono County to determine water availability and use in the northwest corner of the Mono Basin with respect to habitat restoration plans. Funding: NASA.

Remote Sensing of Snow Water Equivalence in Montane Watersheds
Walter Rosenthal, Institute for Computational Earth Systems Science, UCSB Ph.D.
Advisor: Jeff Dozier, Institute for Computational Earth Systems Science, UCSB
An unsupervised algorithm was developed to estimate snow-covered areas at subpixel resolution from multispectral image data. Classification trees fragment the data set along boundaries of distinct land and cloud cover classes. The dimensionality and number of endmembers for each image fragment are determined from principal components analysis. Endmember spectra are converted to surface reflectance with an atmospheric radiative transfer code, and the endmembers are identified by automated search of a spectral library. The final snow cover estimate is a composite of the best mixture model per pixel, adjusted for endmember impurity. The algorithm was tested on Landsat Thematic Mapper data against high resolution aerial photographs and found to yield equivalent estimates of snow cover fractions. Estimates of snow-covered area must be combined with estimates of snow depth and density to yield estimates of spatially distributed snow water equivalence. Snow depth was measured with an L-band FMCW radar operating from an aerial tramway at Mammoth Mountain up to 70 meters above the ground. Snow depth, wetness, and slope varied greatly along the 2.4 km transect. Radar measurements were compared against concurrent manual depth probes, and good agreement was found between the estimates. The results suggest that deep snow packs in rugged terrain can be accurately and safely surveyed by helicopter-borne radar. Funding: NASA; U.S. Army Corps of Engineers.

Land-Surface Temperature Validation 
Zhengming Wan, Institute for Computational Earth System Science, UCSB
Thermal infrared field measurements were conducted with a TIR spectrometer, radiometers and thermistors at a snow field near Highway 395 and 120 on March 10, 1998, a clear day. Two airborne flights with the visible-and-TIR sensor MAS (MODIS Airborne Simulator) passed the Mono Lake and Mammoth Lake area, one around 11:00 PST and another around 22:00 PST. One radiosonde balloon was launched during each of the flights to measure atmospheric temperature and water vapor profiles. Preliminary analysis shows that land-surface temperature measured by field instruments matches well with the land-surface temperature retrieved from the MAS data. Comprehensive analysis of the field and airborne measurement data will be made in the following months. Funding: NASA.

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Terrestrial Botany

Causes and Consequences of Context-Dependency in Rangeland Recovery After Livestock Grazing Eric Berlow and Carla D'Antonio, Department of Integrative Biology, UC Berkeley
We are beginning our second field season in montane meadows of the Kern Plateau in the southern Sierra Nevada, and are investigating the expansion of woody shrubs (sagebrush) and the re-invasion/recovery of herbaceous species after the cessation of livestock grazing. There is great interest in restoring these meadows to a condition where herbaceous species are dominant, yet the processes governing the interaction of sagebrush and meadow herbs appear to be highly variable over space and time. Our goal is to better understand the contingencies that regulate variation in sagebrush expansion and herb meadow recovery so that we can better predict a) specific restoration mechanisms that are most appropriate for a given area, and b) temporal 'windows of opportunity' for implementing restoration plans when they are most likely to be successful. Funding: National Science Foundation Postdoctoral Fellowship for Biosciences Related to the Environment; Hellman Fund.

Induced Defense in Wild Tobacco Plants Following Clipping of Neighboring Sagebrush 
Richard Karban, Department of Entomology, UC Davis
Wild tobacco, Nicotiana attenuata, is a native annual that grows in the Great Basin, often in close proximity to sagebrush, Artemisia tridentata. Previous laboratory experiments demonstrated that cut branches of sagebrush released volatile methyl jasmonate that induced solanaceous plants to increase synthesis of putatively defensive secondary chemicals. However, whether such processes occur under field conditions and whether they can be ecologically important has never been evaluated. We found that wild tobacco plants growing near clipped sagebrush received less damage by leaf feeding herbivores than tobacco plants near unclipped sagebrush. This effect was found in both of two field seasons when cutworms and grasshoppers were the primary herbivores. This large effect translated into enhanced performance of wild tobacco plants near clipped sagebrush, measured as the maximum number of leaves produced, height, number of flowers produced, number of capsules, and seed mass. Several mechanisms in addition to interplant communication could have produced this large effect of clipped sagebrush protecting nearby tobacco. Herbivores may feed less on tobacco near clipped sagebrush because of volatiles released by clipping; this hypothesis was not supported in field experiments with caged grasshoppers. Clipping nearby sagebrush may allow more light to reach tobacco plants making them more resistant than plants next to unclipped sagebrush neighbors; this hypothesis was also not supported by shading experiments. Communication can occur by any of several potential signal pathways and experiments are underway to evaluate these possibilities. Funding: U.S.D.A. N.R.I.

Effects of Elevated CO2 on Jeffrey Pine using F.A.C.E. Technology in the Inyo National Forest 
Walt Oechel, Department of Biology, San Diego State University, San Diego 
Steven Hastings, Global Change Research Group, San Diego State University 
George Koch, Department of Biology, Northern Arizona University, Flagstaff 
Christopher Farrar, U.S. Geological Survey, Carnelian Bay, California Franco 
Miglietta, IATAS-CNR, Florence, Italy
The aim of this project is to quantify the amount of CO2 that is being emitted into the LADWP Mono Tunnel aqueduct which runs under the Inyo National Forest. Once we have determined how much CO2 is available we intend to utilize this resource in elevated CO2 experimentation on Jeffrey Pine. Initial data collected in February of this year indicates that a minimum of 20 tons of CO2 per day is released. Further measurements were precluded due to the heavy snowfall. These preliminary data are very encouraging and we will return during the summer to measure over a longer period of time. Each end of the 11 mile tunnel was sealed off and the bulkhead at J shaft (approximately 870 feet above the tunnel, in the June Lake area) will be opened to allow us to install a large volume blower. By the middle of July we will spend 1-2 weeks at J shaft and collect the CO2 output data and prototype a system to treat 2-3 meter tall pines. Funding: National Science Foundation.

Energy Supply Limits on the Reproductive Activities of Male Ground Squirrels
Gwen Bachman, Department of Zoology, University of Oklahoma
The project's primary goal is to assess whether and how energy supply limits the reproductive activities of male ground squirrels. We hope to determine (i) the relationship between individual variation in male reproductive behavior and daily energy expenditures, and (ii) the extent to which individual reproductive activity is limited by stored energy reserves and intake during the mating period. These questions will be examined in two species of ground squirrels with contrasting forms of intrasexual competition: the thirteen-lined ground squirrel (study site in Oklahoma) and the Belding's ground squirrel (study site at SNARL). The mating system of the 13-lined squirrel emphasizes mate searching behavior with minimal male-male combat, whereas the Belding's mating system is thought to emphasize male fighting ability. These tactics are common features of many mammalian systems. A sample of males was followed throughout the breeding period with the aid of radio transmitters mounted on collars. Location and activity of males was noted every 15 minutes for 9-10 hours each day. We also measured energy expenditure and body composition changes in males differing in activity level and experimental treatment. This year, we provided some males with access to extra food for part of each day to examine whether food availability and foraging time limited mating effort or mating success. Funding: National Science Foundation's Visiting Professorships for Women.

Begging Energetics in Passerine Birds
Mark A. Chappell, Department of Biology, UC Riverside Gwen Bachman, School of Biological Sciences, University of Nebraska
We measured the aerobic capacity for exercise in 3 to 10 day old House Wren nestlings (Troglodytes aedon) at the Sierra Nevada Aquatic Research Laboratory. The exercise data were compared to previous measurements of the energy cost of begging (Ebeg) to determine if begging chicks are working at maximal exercise capacity. We also compared exercise to the peak metabolic rate during digestion and, in older chicks, to thermostatic heat production. Rates of oxygen consumption (VO2) during exercise increased rapidly with age, but the factorial aerobic scope for exercise (exercise VO2 / resting VO2) was low. The mean Ebeg was consistently lower than exercise VO2, but maximal Ebeg was similar to exercise VO2. The peak VO2 during digestion was higher than exercise VO2 for young chicks but not significantly different for older chicks. In 8 to 10 day old chicks, regulatory thermogenesis at 22° C was significantly greater than exercise VO2. These results suggest that some begging by House Wren chicks represents a maximal muscular effort, but the average output during begging is probably not constrained by exercise capacity. The metabolic capacity for muscular activity of any kind is lower than the metabolic capacity for digestion (at least in young chicks), which presumably reflects a high priority for food processing and growth. Funding: UC Riverside Academic Senate; National Science Foundation.

The Systematics, Ecology, and Biogeography of Coleoptera in the Eastern Sierra 
Roger Dajoz, Museum of Natural History, Paris, France
We have visited SNARL four times, spending about 50 days each year in July and August, studying the systematics, ecology, and biogeography of the Coleoptera belonging to the dendrophagus fauna and the soil fauna. The areas that have been visited range from Sonora Pass to the north to the White Mountains in the south. The species of trees hosting the target fauna include Jeffrey Pine, White Fir and Red Fir. The survey provides an idea of the Coleoptera taxa that exist in the central Sierra; a fauna which is not yet well-known. We have studied the succession of insects associated with the decay of trees (from ailing tree to the completely decayed tree) and the succession of insects that live in the fungi on trees (Polyporaceae). These data will be compared with those collected in Arizona and in various parts of Europe. The biology of some notable species has been studied (i.e., the larva of a still unknown species of Carabidae and the biometry and allometric growth of Cerambycidae (longhorn beetles)). The soil Coleoptera have been studied in various areas, particularly in the White Mountains and near Sonora Pass. The two most important families are Carabidae and Tedrionidae. Among the data already published are the discovery of a new species of Tenebrionidae of the genus Areoskizus which lives with ants and a new species of Carabidae in the genus Callisthenes which has been found only in a restricted area near Mammoth Lakes and which is very likely a Sierra Nevada endemic species. The Coleoptera that live in riparian areas also have been studied. The main families are Carabidae, Staphylinidae, and Heteroceridae. Notable species have been found near Fish Slough, Mono Lake, Walker Creek, and Crowley Lake. Funding: Self-funded.

Field Studies of Sage Grouse 
Lek Mating Behavior in Long Valley 
Robert Gibson, Department of Biology, UC Los Angeles
This is a multi-year project examining patterns of genetic relatedness in sage grouse, using microsatellite DNA markers. This research builds on our previous behavioral studies of a population of sage grouse in Long Valley adjacent to SNARL-VESR, which provides a base for the field work. Funding: National Science Foundation.

Latitudinal Effects on Hormone-Behavior Interactions and Mate Fidelity in Temperate Zone Birds 
Rachel N. Levin, Department of Biology, Pomona College
The study of bird behavior and physiology has made a major contribution to our understanding of vertebrate reproductive behaviors in general. In part, this is because birds are abundant, easy to work with, and easily maintained and manipulated in captivity. Much of our basis for understanding avian reproductive behavior and its underlying mechanisms comes from the study of birds in the temperate zone. However, recent work suggests that tropical birds may differ dramatically from temperate birds, both in their behavior and endocrine control. Specifically, previous work by the PI has suggested that latitude may have a mediating effect on the hormonal control of song and other reproductive behaviours such that tropical birds have low levels of reproductive hormones and reproductive behavior may be entirely independent of hormonal control. To begin to address this possibility, we plan to take advantage of the wide distribution of the house wren, Troglodytes aedon, to conduct comparative studies of the interactions of hormones and behavior in temperate and tropical populations of the same species. The procedures that we are employing for this research will also allow us to address another major aspect of reproductive biology, i.e., mate fidelity and extra-pair copulations. The results of this study will have broad implications for our understanding of the control of the reproductive behavior of all vertebrates, including humans. Funding: Hirsch Research Initiation Award, Pomona College.

Social Recognition in Ground Squirrels 
Jill M. Mateo, Department of Psychology, Cornell University In collaboration with Robert E. Johnston, Cornell University
The general goal of my research at SNARL is to describe the mechanisms of social recognition in ground squirrels, focusing on olfactory cues as a means of discrimination. In 1997, I established that Belding's ground squirrels produce at least three individually distinct odors (secretions from oral, dorsal, and anal glands), which may be used for individual identification. These odors are generalizable, in that squirrels do not differentiate between two odors (such as oral and dorsal) from the same individual. This suggests a higher-order representation of familiar individuals. Preliminary data indicate that oral and dorsal glands also produce kin-distinct odors; that is, odors that are more similar among relatives than non-relatives. Thus ground squirrels could use these odors as markers of relatedness to facilitate kin recognition. Pilot data suggest that squirrels can, in fact, discriminate odors from unfamiliar individuals varying in relatedness to them (such as grandmother, aunt, half-aunt). Squirrels continue to recognize their kin after a species-typical period of hibernation of eight months. However, they no longer recognize previously familiar non-kin in the spring, suggesting that familiarity (e.g. of neighbors or colony members) must be re-established each year. Data from free-living animals demonstrate that adult females use olfactory communication to demarcate and defend their burrow systems. In addition, mutual investigation of oral glands often precedes both amicable and agonistic social interactions. Funding: Department of Psychology, Cornell University; National Science Foundation.

Geographic and Altitudinal Variation in Water Balance of the Grasshopper, Melanoplus sanguinipes 
Bryan Rourke, Department of Ecology and Evolutionary Biology, UC Irvine
1) Water-loss measurements and flow-through respirometry: Adult grasshoppers from UC NRS sites at Sierra Nevada Aquatic Research Lab, Angelo Coast Reserve, and Hastings Reserve, as well as The Nature Conservancy's Santa Rosa Plateau, and the WMRS Crooked Creek facility were field-caught and transported back to the lab. Individual total water loss and carbon dioxide emission at 35o C were recorded using flow-through respirometry in a temperature controlled cabinet. Significant differences in water-loss among populations were found, and carbon dioxide emission (used as an indirect estimation of metabolic rate) among populations are different as well. 2) Average field temperature and relative humidity: Data loggers were placed at all five sites to record hourly air and soil temperatures, as well as relative humidity. In some cases, historical climate data were also obtained from weather stations, providing information on weather trends for over 50 years. Weather data and field body temperature measurements may correlate with average lipid melting points for the populations. 3) Role of lipid physical properties in cuticular water permeability: Grasshoppers from all five populations were used to study the effect of lipid phase transition on the transition point for water loss in vivo. Live and incapacitated (via cyanide vapor) grasshoppers were placed in a temperature controlled respirometry chamber as the temperature was ramped from 30 to 60o C. Water loss measurements and subsequent curve fitting revealed a transition point in water loss; lipid melting point for the same individual were determined by FTIR spectroscopy. Highly significant correlations were found between transition temperature and lipid melting temperature in both live and cyanide-treated individuals, providing some of the first ever data of this kind. Funding: Sigma Xi; White Mountain Research Station; National Science Foundation.

An Experimental Investigation of Factors Affecting Renesting in Sage Grouse 
Kathleen Semple, Department of Biology, UC Los Angeles Ph.D. Advisor: Robert Gibson, Department of Biology, UC Los Angeles
During May 1998, 7 female sage grouse (Centrocercus urophasianus) were captured using cannon nets and fitted with radio-collars. The nests of 4 adult and 2 yearling females (one yearling died) were found and their clutches were taken as part of another study (permission granted by UC Los Angeles and UCSB Animal Care Committee and California Department of Fish & Game). This study was designed to investigate the factors affecting renesting decisions by sage grouse depending on their age, body reserves, lateness of season and nest habitat characteristics. As of the end of June, 1998, 2 adult females had second nests, one yearling had settled into her summer range without renesting and the other yearling died. The behavior of the two remaining adults indicates that they may be laying/incubating second clutches. The nesting season continues at the time of this writing, therefore I will analyze how season, age, body reserves and nest habitat characteristics affect the occurrence of renesting when I can positively determine whether each female has renested. Funding: UC NRS Mildred E. Mathias Graduate Student Research Grant.

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