The project’s goal is to assess whether and how energy supply limits the reproductive activities of male ground squirrels. I will be conducting observations on Belding’s ground squirrels, which in many ways typify male breeding strategies in other mammals. Males both fight and search for females. Body fat may have a role in fueling their success but how this fat is acquired, and at what cost is unknown. Using a combination of field experiments, observation of behavior, measure of energy expenditures, estimates of body composition, dissection, and measures of metabolic rate, I will be able to address 3 major issues in animal behavior and ecology: 1) the relationship between individual variation in male reproductive success and the allocation of time to different activities, 2) the extent to which individual reproductive activity is limited by stored energy reserves, and 3) the ecological and physiological costs to acquiring the energy used for breeding. This investigation will provide definitive data relevant to the role of energy in male reproductive success, and will provide a firm link between behavior and an individual’s ecological circumstances (food supply, and the risks they take to acquire food). The research site extends from Tioga Pass onto Dana Meadows in Yosemite. Funding: University of Nebraska.

Spatial Patterns in Physical Factors and Biological Interactions for Periphyton Communities

Lilian Busse, Department of Ecology, Evolution, and Marine Biology, University of California at Santa Barbara

In this study, we will examine responses of algal physiognomy and species composition to the presence of grazers across a gradient of nutrient enrichment. My primary goal is to show the relative importance of resource limitation vs. grazer control for periphyton biomass, physiognomy, and species composition across seasons and in different stream systems. Subsidiarily, we want to test the hypothesis that the growth of filamentous green algae can only temporarily override grazer control, and that grazers can suppress periphyton biomass after filamentous algae are lost due to senescence and sloughing. By examining the importance of top-down and bottom-up control, we can develop predictive models which describe the important determinants of stream ecosystem dynamics and allow us to make predictions about the effects of human perturbations on a stream system. Funding: German Academic Exchange Program.

Vertical Mixing Rates in Mono Lake: Implications for the Duration of Meromixis

Jordan Clark, Department of Geological Studies, University of California at Santa Barbara

In lakes, vertical (diapycnal) mixing rates profoundly influence the chemistry and biology by transporting material from different depths. Nutrient dynamics, release of dissolved gases, and net primary production from phytoplankton are all dependent to some extent on vertical mixing and the ensuing transport of dissolved and particulate materials. The proposed work will quantify, for Mono Lake, vertical mixing rates using sulfur hexafluoride (SF6). SF6, a non-reactive and non-toxic gas, has been successively used to quantify both vertical and horizontal mixing rates in large continental systems including the tidal Hudson River, Lake Constance, and Lake Alpnach. It has been used previously in Mono Lake during a gas exchange experiment. The proposed study will use sulfur hexafluoride (SF6) to quantify lake-average vertical mixing rates with time scales of days to weeks. The experiments will be coordinated with the research program of Dr. Sally MacIntyre who is investigating vertical mixing in Mono Lake and is currently funded by the National Science Foundation. Funding: Centers for Water and Wildland Resources.

Studies on Snow Physics, Distributed Modeling of Snow Processes and Avalanche Forecasting Aids

Robert E. Davis, Department of Geophysical Sciences, United States Army CRREL

Walter Rosenthal, CRREL Contractor & MMSA, University of California at Santa Barbara

Susan Burak, CRREL Contractor_Rick Kattelmann, Institute for Computational Earth System Science, University of California at Santa Barbara

This project develops methods to spatially distribute models of snow cover and methods to measure the spatial properties. Measurements of forest properties as well as snow characteristics support this work, which primarily uses Mammoth Mountain as a test site. Funding: Department of Defense; US Army Corps Sacramento District; NASA.

Monotunnel Carbon Dioxide Investigation

Christopher Farrar, Department of Water Resources, U.S. Geological Survey

An investigation of the known high carbon dioxide discharge from the Mono-Tunnel will be carried out. The tunnel is part of the Los Angeles Department of Water and Power water conveyance system that takes water from the Mono basin and discharges it into the headwaters of the Owens River in Long Valley. The investigation is aimed at quantifying the CO2 discharge, characterizing the variability in discharge over a period of months, determination of the causes of variations, determining the source of the CO2, and the biologic effects of the CO2 on vegetation downwind of the tunnel. The ultimate objective of the study is to use the naturally high CO2 discharge as a way of investigating the potential effects of the global atmospheric increase in CO2 on vegetation. Funding: OESCHI.

Assessment of Rangeland Stream Health Using Biological Indicators of Water Quality

David Herbst, Sierra Nevada Aquatic Research Laboratory and Marine Science Institute, University of California at Santa Barbara

We will use aquatic insects as indicators of water quality and the health of habitats exposed to various land use practices. Field studies will be conducted in the eastern Sierra Nevada and Northern Nevada. Funding: Environmental Protection Agency.

Fumarolic Meteoric-Hydrothermal Circulation in Hot Volcanic Rocks

Elizabeth Warner Holt, Department of Geological and Planetary Sciences, California Institute of Technology

The interaction of meteoric water (i.e. groundwater, rivers, lakes, snow, and ice) with hot volcanic rocks forms a particular type of hydrothermal system driven by the heat in the newly emplaced volcanic rocks. These hydrothermal systems are necessarily very short-lived, and involve vigorous, high-temperature circulation of water through the upper part of the volcanic unit. _This study investigates the oxygen isotope effects of such hydrothermal circulation. The interaction of meteoric water with the hot volcanic rocks during this process leaves a fingerprint of its passing, because the oxygen in the water exchanges with the oxygen in the rock._The Bishop Tuff fossil fumaroles, located between Long Valley caldera and Bishop on the volcanic table land, are an excellent example of rocks that have hosted this kind of hydrothermal system. The pathways of fluid flow through the upper part of the Bishop Tuff may be traced out by mapping fumarolic structures and determining the oxygen isotopes of selected samples. Funding: California Institute of Technology.

Responses of a Saline Lake to Environmental Change

Robert Jellison, John Melack, Marine Science Institute, University of California at Santa Barbara

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 at the smaller lake size caused by diversions of freshwater streams out of the basin. In 1994, state agencies decided to gradually raise the surface elevation of Mono Lake to ~1948 m, approximately six meters above the historic low in 1982. This action provides an 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 increasing salinity. Funding: National Science Foundation.

Snow Modeling for GCMs

Jiming Jin, Hydrology and Water Resources, University of Arizona Funding: World Lab.

Induced Resistance and Interplant Communication

Rick Karban, Department of Entomology, University of California at Davis

John Maron, Department of Botany, University of Washington

It is now well accepted that plants increase their defenses after herbivory. In addition, it has been suggested that plants near damaged neighbors may also become more resistant, although this hypothesis is undocumented. Previous work at Sierra Nevada Aquatic Reserve Laboratory has indicated that induced tobacco plants become more resistant to tobacco hornworms. In addition, tobacco plants with damaged sagebrush neighbors suffered less herbivory than tobacco plants with undamaged sagebrush neighbors. This experiment will be repeated during this field season. In addition, experiments will be conducted to determine whether this results from increased plant resistance or some other change. Finally, collaborative work will be done with three chemical labs (Ian Baldwin, Roxanne Brandway, and Gary Felton) to determine the nature of the changes. Funding: US Department of Agriculture.

Impacts of Introduced Trout on Sierran Lake Ecosystems

Roland Knapp, Marine Science Institute/Sierra Nevada Aquatic Research Laboratories, University of California at Santa Barbara

Although the introduction of trout into lakes and streams of the Sierra Nevada has traditionally been viewed as a beneficial activity, recent research indicates that trout can have major impacts to the structure of native aquatic communities. As a result, land and resource management agencies are increasingly concerned with the impacts of non-native trout on the Sierra Nevada. The goal of our research is to 1) conduct a large-scale sampling program for fish, amphibians, zooplankton, and benthic invertebrates in the Sierra Nevada, 2) use this distributional information to identify native species that may be particularly sensitive to trout introductions (species that are preyed upon and show extensive habitat overlap with introduced trout), 3) to model the spatial distribution of trout under different trout stocking scenarios, and 4) to use the results of this model to identify potential networks of fishless waters that could serve as refugia for sensitive aquatic species. This research is being conducted in the John Muir Wilderness near the Sierra Nevada Aquatic Research Laboratory. We anticipate that our results will help land and resource managers to design management strategies that protect native species while maintaining and even enhancing a popular non-native trout fishery. Funding: U.S. Forest Service.

Effects of Exotic Eradication on the Recovery of Ecosystem Structure and Function

Roland Knapp, Marine Science Institute, University of California at Santa Barbara

Ace Sarnelle, Department of Fisheries and Wildlife, Michigan State University

Invasions of exotic species into ecosystems worldwide have exploded during the past several decades, often causing large alterations to community structure and ecosystem function. Our research examines how ecosystems respond, not to invasion, but to the elimination of an exotic species. Study of exotic eradication provides a rare opportunity to study the fundamental ecological process of community assembly in nature. This research examines the recovery of alpine lake systems in the Sierra Nevada, California, after the eradication of exotic trout. A multi-faceted approach is taken that utilizes long-term whole-lake experiments, small-scale species manipulations, paleoecological analyses, and bioenergetics/mass balance modeling. Combined with a recently completed large-scale study of lake recovery (200 lakes), this approach will allow the quantification of ecological responses to release from perturbation over a wide range of spatial and temporal scales. Funding: National Science Foundation.

Deformation of the Long Valley Caldera from Precise Measurements of Temporal Gravity Changes, Supplement Leveling and GPS Data

Sophie Leblanc, Departement de Geologie, Universite de Montreal

The goal of this study is to better understand the causes of the deformation rates in the Long Valley caldera. I will interpret temporal gravity changes in terms of gravity/elevation which are indicators of mass and/or density variations. This data will enable me to better understand the magmatic-hydrothermal system in Long Valley. I will also be analyzing trace elements in biotites from Obsidian Dome, Deadman Creek Dome and Bishop Tuff to see if these different volcanic events were fed to the same magmatic reservoir. Funding: Fonds Canadien Assistance a la Rercherche (FCAR).

Latitudinal Effects on Hormone-Behavior Interaction and Mate Fidelity

Rachel N. Levin, Department of Biology, Pomona College

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 in endocrine control. Latitude may have a mediating effect on the hormonal control of song and other reproductive behaviors such that tropical birds have low levels of reproductive hormones and reproductive behavior may be entirely independent of hormonal control. If this is true, it would be exciting evidence that environment can have a direct, mediating influence on hormone behavior interactions. 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 interaction of hormones and behavior in temperate and tropical populations of the same species. We therefore propose to assess circulating hormone levels, song, and reproductive behavior in populations at two sites in Southern California, one lowland (near Claremont) and one at higher elevation (Sierra Nevada Aquatic Reserve Laboratory), to represent the north temperate zone, and at lowland and highland sites that we have established in Panama to represent the tropics. We predict that we will find a relationship between hormone-behavior interactions in the north temperate zone and that this will not be the case in our tropical populations. If our hypothesis is supported, then we hope to test it further by sampling two south temperate populations (near Bariloche, Argentina). Funding: Hirsch Research Initiation Award.

Vertical Mixing and Resource Supply to Phytoplankton

Sally Mac Intyre and John Melack, Institute for Computational Earth System Science, University of California at Santa Barbara

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 times 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 pynocline. In addition, in 1998, Jordan Clark injected a tracer, sulfur hexafluoride, just above the top of the pynocline. His data, combined with our turbulence 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 calculation of 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 photoadaptation of phytoplankton. N. Scully measured the distribution of hydrogen peroxide in Convict Lake. H2O2 is photochemically produced in the surface water 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 measurement of ultraviolet ration 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.

Herbivory on Wild Tobacco

John Maron, Department of Biology, University of Washington

The purpose of this research is to understand how herbivores influence the population dynamics of wild tobacco. In experimental plots that have already been burned, populations of tobacco plants will either be protected, or exposed to herbivory. In the future, plots will be reburned to determine whether reduction in plant production, due to herbivory reduces seedling emergence out of the seedbank. Funding: University of Washington.

Mechanisms of Social Recognition in Ground Squirrels

Jill Mateo, Department of Psychology, Cornell University

The general focus of this research at Sierra Nevada Aquatic Reserve Laboratory is to describe the mechanisms of social recognition in ground squirrels, focusing on olfactory cues as a means of discrimination. 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 generalized, 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 reestablished 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 preceded both amicable and agnostic social interactions. Funding: National Science Foundation.

Web-Based Environmental Management Pilot Study

Emil Morhardt, Department of Joint Science, Claremont Mckenna College

Funding: Claremont McKenna College; Scripps College.

Late Quaternary Climatic and Limnological Changes in the Eastern Sierra Nevada

David Porinchu, Department of Geography, University of California at Los Angeles

A set of samples of lake water and surface sediment will be taken from 30-50 lakes at different elevations in the eastern Sierra Nevada. The samples will be analyzed for elemental and isotopic geochemistry, chironomid remains, diatoms, pollen, and conifer stomates. We will attempt to link changes in lake water chemistry, chironomids, diatoms, pollen, and stomates to lake air and water temperature, depth and vegetation. Funding: National Science Foundation.

Potential Causes of Declines of Amphibians Reported in Yosemite National Park

Walter Sadinski, Department of Environmental Contaminants, U.S. Fish and Wildlife Service

We are conducting surveys and experiments to test hypotheses regarding causes of declines of amphibians in Yosemite National Park. This includes work on effects of UV-B, pesticides, and climate. The principal field area is from Tuolumne Meadows to Tioga Pass within the park. Funding: Yosemite Fund.

Periphyton Responses to Heterogeneity of Light, Nutrient, and Invertebrate Gazer Levels

William Taulbee, Department of Ecology, Evolution, and Marine Biology, University of California at Santa Barbara

I propose to conduct detailed mapping along an approximately 1 km stretch of Convict creek. The stretch will be chosen so that roughly half of the reach will be exposed to full sunlight, while the other half will be covered by forest canopy with varying light penetration. I will map a variety of state variables, including stream velocity, widths and depths, total suspended solids, nutrient levels, periphyton, and insects. Insect mapping will be non-destructive, and will consist of species identification and species counts along a number of transects at night. Periphyton will be identified along the same transects, and occasional samples will be taken for detailed taxonomic analysis.
Funding: National Science Foundation.

Algal Resources, Prey Behavior, and Predator Impacts on Prey Populations in Streams

Thomas Even, Department of Ecology, Evolution, and Marine Biology, University of California at Santa Barbara

The objectives of this research are to: 1) explore the effects of invertebrate (stove flies) and vertebrate (trout) predators on the structure of stream macroinvertebrate communities, 2) determine the influence of algal resources on the perceived effects of predators on prey population, and 3) examine the role of behavioral responses of prey to predators that may contribute to predator impacts on prey populations. A factorial design that simultaneously manipulates the presence and absence of predators and the position of an algal resource will be used. Experiments will be performed on regulatory structures within the bed of Convict Creek using replicated stream channels. All 24 replicated stream channels can be placed, in parallel, in Convict Creek on a concrete spillway below a small discharge control gate. Funding: Self-funded.

VALENTINE CAMP

RESEARCH:

Demography of Arid-Land Shrubs: Applications for Ecosystem Restoration and Management

Catherine Toft, Section of Evolution and Ecology, University of California at Davis

This study will document demography of desert shrubs along an environmental gradient created by the receding Mono Lake, taking advantage of the transgressing lake to understand physical factors affecting recruitment of juveniles. Shrub demography, seedling survivorship and patterns of thinning at 5 representative sites along the gradient will be continued as part of the long-term study necessary to understand the demography of slow-growing, long-lived desert shrubs. Results will be applied to restoration of Owens Lake bed (and others) that will ameliorate impact of water diversions, primarily air pollution from PM10, and impact of grazing or groundwater pumping on arid range lands. Funding: University of California at Davis Hatch Funds.

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