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Biology and Medicine

The Biology and Medicine program funds research to improve understanding of antarctic life forms and ecosystems – their physiology, behavior, adaptations, and relationships. Projects range across all organizational levels – from the molecule, cell and organism to relationships within communities and ecosystems, to the level of global processes. This is another area of inquiry where scientific goals extend far beyond learning (in this field, about flora and fauna) in the high latitudes.

Antarctica is a place like no other: as an intriguing habitat, a scientist's dream; a land where water is scarce – truly a desert – despite containing more than two-thirds of the world's freshwater supply trapped in the ice. Though it borders the world's major oceans, the Southern Ocean system is unique in the world, a sea where average temperatures don't reach 2ºC in summer, where even the water itself is so unique that it can be identified thousands of miles away in currents that originated here. As the Earth makes its elliptical journey around the sun each year – tilted on its rotational axis – the sun "sets" in April, not to be seen again until September. And the ice – unimaginable, incomparable vastness of ice – in a dozen different varieties, at times and in places several thousand meters thick, two major ice sheets (the East larger than most countries), changing dynamically all the time.

Adaptations and behavior developed in response to these extreme conditions provide insight into the intricacies (as well as the fundamental processes) of evolution. These extremes have also driven the development of ecosystems simple enough to reveal wonderfully clear pieces of the web of life on Earth. Support is focused on the following areas:

• Marine ecosystem dynamics: Among the research topics are understanding the natural variability of marine ecosystems; correlating the structure and function of the marginal ice-zone ecosystem with oceanic and atmospheric processes; exploring the sources of nutrition and their influence on prey and on primary production; and the role of marine phytoplankton in carbon dioxide cycling.

• Terrestrial and limnetic ecosystems: Organisms in ice-free areas and in perennially ice-covered lakes show remarkable adaptations to extreme environments. Relatively few species thrive here, which facilitates the study of ecosystem dynamics and the interpretation of experiments, although much more remains to be learned about adaptive mechanisms and evolutionary processes.

• Population biology and physiological ecology: At the next level, looking at relationships among organisms, studies have focused on the variability and dynamics of populations of krill and other zooplankton; ecological relationships among and between fish species, marine mammals, and birds have also been the object of much research, with many issues still to be further explored. As organized programs of antarctic science enter their fifth decade (some even longer), data sets and ongoing observations are elucidating manmade as well as natural changes.

• Adaptation: Antarctic extremes present a fundamental research opportunity; topics include low-temperature photosynthesis and respiration, enzymatic adaptations and adaptive physiology such as the development in fish of antifreeze compounds and modifications to the circulatory system in seals; also continuing interest in the response of (and impacts upon) organisms to increased UV-B radiation from the ozone hole.

• Human behavior and medical research: Antarctica's extreme climate and terrain impose a quite spartan and unconventional existence upon scientists and others who live and work there. As people are subjected to social, psychological, and physiological stresses (exacerbated during the winter isolation) research opportunities arise. Studies focus on epidemiology, thermal regulation, immune system function, individual behavior, and group dynamics.

Antifreeze protein antarctic fishes: Ecological and organismal physiology, structure-function, genetics, and evolution.
Arthur DeVries, University of Illinois.

Despite temperatures that can dip below 0 °C, antarctic waters provide a life sustaining environment for a number of fish species. How are they able to take the most frigid waters on earth through their gills without themselves freezing? A primary reason are the so-called antifreeze proteins, an adaptation found in a number of polar and subpolar species. These biological molecules have a similar effect to antifreeze in a mechanical engine. The Southern Ocean provides the ideal laboratory and molecular biology the ideal probe to study this phenomenon. As the world's coldest marine environment, the near-shore waters of Antarctica, replete with ice crystals, hover just above seawater's freezing point. We are studying the physiology of fish and larvae from these waters to see how ice wants to grow in biological tissues - a crystallization process called nucleation - and how antifreeze glycoproteins (AFGP) inhibit it.

Their evolution of the antifreeze function has enabled the antarctic notothenioids to colonize their frigid habitats very successfully. We are mounting comprehensive multidisciplinary analyses of this adaptation at the level of the gene as well as the protein. Specifically, we will -

• examine the structure of antifreeze proteins;

• refine the molecular model of how these proteins adsorb ice and inhibit ice crystal growth;

• study the physiological parameters governing the natural growth of ice crystals;

• pinpoint the chromosomal locus of the gene family and its protease progenitor gene;

• sketch its evolutionary history by calibrating the rate of notothenioid nuclear protein coding sequences; and

• focus on when these AFGPs develop during embryogenesis and early larval stages. (BO-005-M)

Use of a long-term database and molecular genetic techniques to examine the behavioral ecology and dynamics of Weddell seal (Leptonychotes weddellii) population.
Donald B. Siniff, University of Minnesota-Twin Cities.

The Weddell seal (Leptonychotes weddellii) is found in regions of pack ice or fast ice close to the antarctic continent. These seals are relatively long-lived, and the waters of McMurdo Sound have provided a continuous environment in which to study their survival and aquatic reproductive patterns. A series of long-term population studies, ongoing since the mid-1960s, have generated a rare and valuable set of data.

Recently developed molecular biology techniques, however, permit scientists to examine the DNA of individual seals as well as groups, and to gain insight into their genetic histories, breeding systems and reproductive fitness. Breeding males behave characteristically; looking at this behavioral ecology and their mating systems through the lens of their DNA permits scientists to project backwards in time and correlate the seals' reproductive success with the effective size of their populations. Using and building on the long-term data set, our study will also examine how hypotheses can be tested and parameters can be estimated, in producing models and studies of population demographics. We will also explore the population dynamics of the Weddell seal though the lens of immigration and emigration into and out of the group. Several collaborative efforts will occur this season. In one, blood, scat and diet samples will be collected for researchers studying Weddell seal blood chemistry, health parameters, blood parasites and diet. In another, some of the seals will be mounted with small video cameras to provide data for Japanese scientists studying diving and other underwater behaviors of free-ranging seals. And a remote camera surveillance will be set up to observe the spacing patterns of adult females on the ice surface and underwater.

As the southernmost breeding mammal in the world, the Weddell seal exemplifies the ability to adapt to environmental extremes. Understanding the mating strategies these seals employ should contribute to a deeper understanding of the evolution and population dynamics of the Pinnipedia (a suborder of aquatic, carnivorous mammals, including all the seals and walruses) in particular, as well as how marine mammals more generally, compete. (BO-009-O)

Studies on the impact of sewage-associated microorganisms on indigenous seal and bacterial populations and drinking water quality at McMurdo Station. John Lisle, Montana State University.

Human impacts on the environment are typically complex and often reverberate through a wide ecological spectrum. While a comparatively pristine environment, Antarctica is still a populated continent, with all of the inherent issues and challenges of environmental protection. For years, human sewage has been released into the seawater at McMurdo Station, untreated except for the process of maceration (which dilutes or softens a material by steeping it in liquid). What are the impacts on the marine ecosystem? This project focuses on bacteria known to thrive in the sewage deposits, tracing their progress into the drinking-water intake at Intake Jetty, and also into other organisms and indigenous species, such as Weddell seals. One of the bacteria previously associated with this problem is clostridium perfringens, which researchers have suspected were colonizing Weddell seals in the area of the sewage. These and other deposit-feeding invertebrates appear to assimilate the nutrients associated with the sewage and to increase body mass and organ sizes. These earlier results are driving this work, which will use more advanced genetic molecular biology and more sensitive culture-based techniques to determine a number of issues. Are the sewage-associated bacteria and viruses the specific ones that are colonizing Weddell seals? Are these microorganisms exchanging their DNA with indigenous species, thus potentially altering the procaryotic gene pool of this ecosystem? Are they entering the drinking water system at McMurdo Station? The microbiological quality of marine and drinking waters at McMurdo Station is currently monitored, but are we underestimating the risks to the marine environment and to human health?

The results from this study should help to evaluate current monitoring systems and to design remediation efforts. A sewage treatment plant is currently planned for McMurdo Station, and these data will provide a baseline for efforts and studies of ecosystem recovery. The data will shed light not only on the coastal waters off of McMurdo Station, but also on other coastal waters around Antarctica that may be similarly affected by the discharge of untreated human sewage. (BO-024-O)

The biogeochemistry of dimethylsulfide (DMS) and related compounds
in a chemically stratified antarctic lake.

John C Priscu, Montana State University, and Giacomo R. DiTullio,
Grice Marine Laboratory, University of Charleston.

The earth's atmospheric cycle involves continuous transport of basic elements, one of which is sulfur. Dimethylsulfide (DMS) is the dominant volatile sulfur compound emitted from the ocean and may represent up to 90 percent of the sea-to-air biogenic sulfur flux. When these volatile sulfur molecules oxidize in the atmosphere, condensation nuclei can be released which, scientists hypothesize, may directly counteract the warming effects of anthropogenically produced CO2. Aquatic systems - in particular the waters of the south polar regions - thus play a crucial role in one of the planet's basic transactions. Yet both the sources and the sinks of DMS and associated sulfonium compounds have yet to be fully identified and understood.

This research will examine the biogeochemistry of water column and sedimentary DMS/DMSP (dimethylsulfoniopropionate), and the role of associated compounds (e.g.,dimethylsulfoxide, dimethylated polysulfides) in Lake Bonney. This relatively simple aquatic system provides a highly tractable environment for investigating the microbially mediated cycling of biogenic sulfur because it contains no grazers, no turbulence and little atmospheric exchange.

Preliminary data suggest that maximum levels of DMS precursors may be found in the deep-chlorophyll layer of the lake, a zone dominated by cryptophyte algae. In addition, DMS concentrations deep in the lake, where there is very little light (i.e., in the aphotic waters), are among the highest recorded in any natural aquatic system. These observations indicate that precursors produced by trophogenic zone phytoplankton sink to the aphotic waters and sediments, where microbes decompose them to DMS and other sulfur compounds. The proposed research will define the sources and sinks of DMS and associated compounds, and establish how they function in the overall ecosystem. We hope to develop a model describing the biogeochemical transformations of organo-sulfur compounds in Lake Bonney. (BO-025-O)

Temperature compensation in antarctic pteropods: An integrative approach.
Robert Dudley, University of Texas at Austin.

Life in frigid polar waters reveals many adaptations; creatures have developed physiologic specializations so as to function and react more effectively in the cold. The long-standing hypothesis holds that animal taxa indigenous to these climates evolved the ability to regulate basal and active metabolic rates better than their temperate-zone counterparts; but this theory remains contentious and - in any event - has been applied only to fish and benthic invertebrates. Polar pteropods, small gastropod molluscs commonly found in antarctic zooplankton, are abundant, metabolically active, and provide a different species (another taxon) in which to probe thermal compensation mechanisms that may serve the physiological processes underlying locomotion.

To explore these phenomena, we will use two different sister pteropod species, one from the polar and one from a temperate zone. Experiments will focus on basal and metabolic rates and mitochondrial energetics; also on biomechanical and on neural responses to different water temperatures and viscosities - all in the context of locomotor performance. The neurons that underlie the swim-system will be evaluated at different temperatures, with particular reference to resting potentials, firing thresholds, action potential durations and ion-channel kinetics. A central question is the extent to which all three aspects (metabolic, biomechanical and neural) may contribute to a coordinated ability to compensate for thermal conditions and extremes in polar pteropods.

Not only should this investigation provide fundamental physiological and behavioral information for this taxon, but we hope to systematically evaluate the hypothesis of cold adaptation across organizational levels in pteropods. We may also be able to shed light more generally on the nature of thermal and locomotor constraints for the many invertebrate taxa living and moving within polar waters. (BO-030-O)

Factors regulating population size and colony distribution of Adélie penguins in the Ross Sea.
David G. Ainley, H.T. Harvey and Associates, California.

Over the past few decades, the Adélie penguin (Pygoscelis adeliae) colonies in the Ross Sea region have grown dramatically in size. What demographic mechanisms might account for this change? This collaborative project will investigate one such possible effect, documented changes in the region's climate. We will look at the birds' nesting habitat as a function of access to food, and hope to distinguish the relative importance of the key resources that constrain the growth of colonies. A number of behavioral and demographic mechanisms may influence a colony's growth, relative to its initial size and distribution pattern. One, for example, is a phenomenon known as philopatry: how breeding effort and success may relate to the balance achieved by immigration/emigration.

As the first empirical study to consider the geographic structuring of a seabird population, we expect our results to increase understanding of how populations regulate themselves, and the patterns they follow when they disperse. We also hope to elucidate the effects of climate change (as indicated by changes in the extent of sea-ice cover) on penguin populations. The results should also provide a context in which to interpret conflicting data on penguin population trends from existing programs; in particular, fluctuations in Adélie penguins have been analyzed as an indicator of such anthropogenic impacts on antarctic resources as fishery catches and disturbances created by tourism. But it is problematic trying to distinguish changes due to man from those caused by nature, without the regional perspective on penguin life history this project is undertaking to develop.

Our 6 years of research include intensive field study of various Ross Island penguin colonies - This season colonies at Cape Royds (4,000 breeding pairs), Cape Bird (35,000), Beaufort Island (35,000) and Cape Crozier (170,000). We quantify reproductive effort and success, food availability (access to food), diet quality, habitat use, and immigration/emigration relative to colony size and environmental conditions (i.e., pack-ice cover).

Landcare Research New Zealand (LCRNZ) has conducted two preliminary field seasons, including the testing of new equipment. This project will build on their results, and they will collaborate with us throughout the lifetime of the project. The LCRNZ work is independently funded. Researchers from the University of California-Santa Cruz, the University of Wisconsin, Point Reyes Bird Observatory, and Beigel Technology, will collaborate with those from H.T. Harvey and Associates and LCRNZ to accomplish the project's goals. (BO-031-O)

Investigations of abandoned penguin colonies in Antarctica.
Steven Emslie, University of North Carolina.

Climate change is assumed to be a pivotal factor in the success of many species. This project will investigate the history of Adélie penguins in late Holocene Antarctica. By locating and examining the fossil remains of former colonies, scientists hope to develop a model of when they thrived and when colonies were abandoned - and thus their success - relative to climate change. This model could inform current science on the relationship between climate and population dynamics.

Our study will integrate data from the ecological, geological and paleobiological records with satellite-imagery analyses. The climate factor will be inferred by data contemporaneous with the fossil evidence, in particular the extent of the sea-ice and marine productivity. The population factor will be developed through field and laboratory investigations of abandoned colonies along coastal Antarctica.

Researchers will first collect surface and subsurface bones, feathers, and eggshell fragments preserved at these sites; later, in the lab, scientists can reconstruct the occupation history of each abandoned colony, through standard and radiocarbon analyses. Sediments from each site will be sifted to recover organic remains (such as squid beaks and fish otoliths) believed to be staples of the penguin diet. Statistical analysis of such indicators can trace the changing size of the colony at specific prehistoric times, and thus prey consumption becomes a proxy for population success. This timeline can then be matched to past episodes of climate change, which are well documented for the late Pleistocene and Holocene in ice-core and marine sediment records.

We expect these ancient responses by penguins to climate change, as indicated by the paleoecological record, to parallel those observed in Antarctica today, where regional warming has been documented over the past 20 to 50 years. Ultimately we will be able to test the hypothesis that Adélie penguins - for decades and centuries - have been responding to climate change in a predictable manner, and that those responses can be anticipated, relative to fluctuations in sea-ice extent and marine productivity. (BO-034-O)

Proteins of oxygen-binding and energy metabolism in muscles of antarctic fishes: Evolutionary adjustments to life at cold temperatures.
Bruce Sidell, University of Maine.

Evolution in the frigid extremes of the antarctic environment has fashioned some useful biological adaptations, at both the physiologic and biochemical level. In some instances, constraints on biological function that might be expected from the cold have been overcome. Also, mutations in antarctic fishes that would probably have been lethal elsewhere are not selected against in the frigid, oxygen-rich Southern Ocean environment. These and other adaptations can be seen in the family of Nototheniidae, which over the last 14 million years has become the dominant fish group in Antarctica - with the most species and the largest biomass of any animal in the ecosystem.

This project explores the role of key intracellular proteins that metabolize energy, as well as other biological mechanisms that enable these fish to function normally at the cellular level - while enduring average body temperature about 0 °C. Experiments will target the physiology and molecular biology of several species of notothenioid fish (who are red-blooded) and the channichthyid icefish, who have no hemoglobin. One line of inquiry pursues why the myoglobin-encoding gene is not expressed. Another analyzes the various different isoforms of creatine phosphokinase that serve the locomotor muscle system. A third explores the basis of the substrate specificity of the enzyme fatty acyl-CoA synthetase (which is involved in the catabolism of fatty acids).

We expect results from this study to further elucidate the evolutionary biology of the antarctic notothenioid fishes, and perhaps also to invoke important general principles applicable to widely different taxa beyond the antarctic. (BO-036-O)

Structure, function, and expression of cold-adapted tubulins and microtubule-dependent motors from antarctic fishes.
H. William Detrich, III, Northeastern University.

Microtubules (subcellular "pipelike" filaments composed of the protein tubulin) and their associated motors, dynein and kinesin, participate in many fundamental cellular processes; such as cell division, nerve growth and regeneration, cell motility, and the organization and transport of organelles within cells. In these processes, the elongated microtubules serve as rigid "railroad tracks" for the movement of motors and their cargoes ( think of them as "trains"), and the motors themselves have the effect of efficient, high-velocity, regulative "locomotives." The microtubules and microtubule motors of cold-adapted antarctic fishes are unique in their capacity to assemble and function at body temperatures (-2¦°C to +2 °C) well below those of warm-blooded and temperate organisms. The long-range goal of our project is to determine functional adaptations (at the molecular level) that serve antarctic fishes in this extreme thermal regime; specifically the assembly of microtubules, the expression of tubulin genes, and the activity of microtubule motors. Our objectives are -

• to determine the structural features (e.g., changes in their amino acid sequences) that enable the tubulins of antarctic fishes to polymerize efficiently at low temperatures;

• to characterize the structure, organization, and expression of an alpha-tubulin gene cluster from an antarctic rockcod (Notothenia coriiceps); and

• to examine the biochemical adaptations required for efficient function of antarctic fishflagellar dynein motors at low temperatures. This season we will also collect some additional species and expand the experimentation to include the expression of genes involved in blood formation. In the broadest sense, this research should advance the molecular understanding of the cold-adapted mode of life. (BO-037-O)

Investigations on deterioration in the historic huts of the Ross Sea region of Antarctica.
Robert A. Blanchette, University of Minnesota.

During the first two decades of the 20th century - Antarctica's "Heroic Era" - Europeans mounted a handful of expeditions in hopes of reaching (and claiming) the geographical South Pole. Base camps established in the McMurdo Sound region - by Scott at Cape Evans and by Shackleton at Cape Royds - were abandoned once the expeditions were over, leaving behind the huts that were built for shelter and storage, as well as thousands of artifacts. Over the past 90 years, the extremes of the polar environment have actually protected some of the artifacts from rapid decay, but conservators have become concerned about serious degradation of what is an important historical, archaeological site.

Some of the most exigent threats: Wood in contact with the ground is being destroyed by a specific wood-destroying fungus. Various molds and cellulose-degrading fungi are attacking artifacts made of leather, textiles, and other organic materials. Exterior wood is being degraded by non-biological deterioration processes as well, including salt, ultraviolet radiation and wind erosion. Chemical damage within the huts is apparent, and the soils on site are contaminated with aromatic hydrocarbons from petroleum products.

We plan to: Identify the biological and non-biological agents responsible for causing the deterioration, study the mechanisms and progressive sequence of events taking place during decay processes, test methods to be used to control future deterioration, determine the extent of environmental pollutants in soils at the historic sites, and evaluate chemical spills within the huts.

The goal is to provide the scientific data required by conservators to help protect these important historic sites for future generations. But the project should also shed scientific light on these unique deterioration processes, as well as augment scientific understanding of the biology of antarctic microorganisms and the biodiversity of microbes present in this unusual environment. (BO-038-O)

Penguin-krill-ice interactions: The impact of environmental variability on penguin demography.
Wayne Trivelpiece, NOAA Southwest Fisheries Science Center.

How well organisms thrive in their environment often reveals itself in basic ecological relationships. For two decades at Admiralty Bay on King George Island in the Antarctic Peninsula region, data have been collected on several species of penguins, including the Adélie, gentoo and chinstrap. Looking at some of the basic aspects of the lives of these predators - such as survival and recruitment, population size and breeding success, and diets and foraging ecology - scientists have been able to develop and test key hypotheses about variability in the antarctic marine ecosystem.

This project focuses on one of these relationships. As the extent of sea-ice cover changes with the season and year-by-year, krill (in the Southern Ocean a key food web species that accounts for nearly 100 percent of the prey eaten by dominant predators such as baleen whales, seals, and penguins) are more or less abundant, directly affecting the population biology of the penguins. Years with heavy winter and extensive sea ice paradoxically favor krill recruitment, because larval krill find refuge and food in the sea-ice habitat. The long-term seabird research indicates that in those same, heavy sea-ice years, Adélie but not chinstrap penguins are also favored.

To explore these relationships, we will capture adult and juvenile penguins periodically to band, measure, and weigh them, and to collect blood and diet samples for genetic and physiologic studies. During the breeding season, the penguins and the sea-ice will be observed by satellite. Another aspect of the population biology of penguins relates to the possible impact of commercial fishing, so this study will provide useful information to the Convention for the Conservation of Antarctic Marine Living Resources, which is the part of the Antarctic Treaty System that focuses on fisheries management.

Microbial mediation of trace metal cycling in four stratified antarctic lakes
William Green, Miami University at Oxford, Ohio.

Aquatic environments often stratify; that is, boundaries at different depths indicate changes in the composition of the water. One of the basic processes in nature is reduction by oxidation(redox); redox boundaries can be found at specific water depths where microbes are implicated in the cycle and fate of a large suite of chemical elements. Thus biogeochemical analyses support limnology - the study of life and the conditions for life in lakes, ponds and streams.

We have been examining the role of microbial influences on metal cycling in four stratified lakes in the McMurdo Dry Valleys: Lakes Fryxell, Hoare, Joyce and Miers, and will focus this season on the latter two. All of these lakes are characterized by unusually stable redox transition zones, and are also especially amenable to a finely spaced sampling regime. Collectively, they represent a broad range of water chemistries. We are testing two hypotheses:

• In stratified water columns there should be a clear spatial difference between the onset of manganese reduction and the onset of iron reduction. Heavy metals and rare-earth elements will be seen to undergo co-cycling with manganese rather than with iron.

• Manganese reduction will be associated with the presence of carnobacteria or other manganese-reducing organisms.

Dissolved and particulate metal profiles will be examined relative to depth - from the ice-water interface at the top all the way down to the sediments. Profiles will be correlated with microbial manganese-reduction assays, and with the presence of manganese reducers; these can be detected by screening with Mn-oxide overlay agar plates and nucleic acid hybridizations that function as probes for known manganese reducers. The research will include significant involvement of undergraduates. (BO-041-O)

Influence of seasonal ice cover on pelagic and benthic communities: Long time-series studies. Kenneth L. Smith, Scripps Institution of Oceanography.

The annual expansion and contraction of ice cover in the Southern Ocean - the largest seasonal process in the world ocean - causes primary biomass production to fluctuate extensively, and has a strong impact on both pelagic (open, upper sea) and benthic (deeper, at the bottom) communities of fauna.

This study at Port Foster, Deception Island, will take advantage of a region that has seasonal ice cover and supports a pelagic and benthic fauna that are representative of the antarctic coastal zone. The study of the water column and seafloor will be structured as a long time-series, employing long-term, autonomous monitoring and sampling systems that were developed especially for use in the antarctic. We will deploy a bottom-moored, upward-looking acoustic instrument on the seafloor for 12 months to monitor the vertical distribution, abundance, and biomass of acoustically detectable macrozooplankton and micronekton in the water column. Collections will be made over this period using newly developed, vertically profiling pump sampling. Simultaneously, a time-lapse camera system will be moored on the seafloor to monitor the spatial distribution, sizes, and movements of the epibenthic megafauna component of the benthic community.

This deployment of instruments will allow us to focus on the effect of the seasonal sea-ice cycle on the distribution, abundance, and biomass of the macrozooplankton and micronekton in the water column. Similar questions about the deeper-dwelling epibenthic megafauna will focus on distribution, size, abundance, and movements. Results from this study should provide a useful foundation database to evaluate the pelagic and benthic community responses to seasonal variability in the Southern Ocean. (BO-050-O)

Diving biology of emperor penguins.
Paul J Ponganis, Scripps Institution of Oceanography.

Because the emperor penguin (Aptenoidytes forsteri) lives within the pack ice zone of the antarctic, its advanced ability to dive has been the subject of interest for many years. Emperor penguins routinely hunt for food for between 2 and 10 minutes, at depths ranging from 50 to 500 meters. These birds have reached a measured depth of nearly 550 meters. The longest dives are not the deepest, however; the recorded longest of twenty-two minutes was nowhere near that record depth. They provide an excellent model to investigate the physiology and behavior of diving birds and mammals; in this study specifically, thermoregulation, underwater behavior and the homoeostatic regulation of myoglobin.

Working with emperors (captured from McMurdo Sound) in a man-made corral with dive holes, we hope to elucidate both the physiological and behavioral mechanisms underlying the breath-holding capacity of these diving birds. To probe how these physiological limits may affect the natural diving behavior and ecology of the penguins, we will focus on the role of decreased body temperature in extending the duration of aerobic metabolism during diving; also we will explore how organs and tissue tolerate oxygen deprivation. Mounting a small camera on some birds will permit us to examine their behavior during their dives, and to correlate changes in body core and muscle temperature with which prey they ingest as well as with their wing stroke frequency.

Another phase of the work involves establishing a second sea-ice camp dedicated to observing the growth and development of young emperor chicks. At the molecular biology level, we will examine transcriptional control of the myoglobin gene to probe the high myoglobin concentration of emperors and the large increases in myoglobin concentration during chick development. All animals will be released at the ice edge at the end of the study. (BO-197-O)

The role of oceanographic features and prey distribution on foraging energetics and reproductive success.
Daniel Costa, University of California at Santa Cruz.

The Southern Ocean enjoys a high seasonal productivity, in both coastal and pelagic environments. But observations over the last several decades show that behind this general productivity lies much variation - during the year and from year to year. Thus, the prey available to vertebrate predators can vary significantly over time and from place to place.

Since the late 1980s, scientists have recorded this spatial and temporal variability for the northern South Shetland Islands region of the Antarctic Peninsula. The antarctic fur seal [Arctocephalus gazella], a subpolar migratory otariid with a short lactation period, is an increasingly dominant marine predator in this region. Its life-history shows a series of foraging trips alternating with short visits to provide for a single offspring; this pattern allows scientists to use the same temporal and spatial scales to measure both maternal investment and the distribution/abundance of prey.

We are trying to quantify the foraging costs and maternal investment associated with different strategies observed in populations of South Shetland antarctic fur seals. Using state-of-the-art techniques (attached to some seals are satellite-trackable transmitters and to others time-depth recorders), we will determine the costs and benefits of different foraging patterns correlated to: Energy expenditure, food intake, dive depth, dive duration, time of day, dive frequency, swim speed, and foraging location. These measurements will coincide with small- and large-scale oceanographic surveys to be conducted by the National Oceanic and Atmospheric Administration's Antarctic Marine Living Resources program, which also contributes to the support of this project.

The research should provide scientists a clearer picture of the life of a free-ranging marine vertebrate predator. We hope to validate patterns linking the biological characteristics of the prey (composition, distribution, and abundance) and the physical characteristics of the foraging environment with foraging success, maternal investment, and reproductive success. (BO-267-O)

Natural product drugs from cold-water marine organisms.
Gregg Dietzman, White Point Systems, Inc.

As with rain forests and jungles the world over, now Antarctica holds the promise of providing natural substances for medicinal uses. Five specific organisms found in antarctic benthos waters have emerged as active leads for developing compounds that might prove toxic to human tumors. In a project co-funded by the National Cancer Institute of the National Institutes of Health, scientists will collect samples (between 1 and 20 kilograms) of these sponges and anemones and bring them back to study their chemistry and biology.

Samples were previously collected in the Antarctic Peninsula region during the 1994- 1995 austral summer. This austral summer, new collection sites north and west of the Palmer Peninsula between King George Island and Palmer Station on Anvers Island will be dredged. (BO-282-O)

McMurdo Station biology course: A training program in integrative biology and adaptation of antarctic marine organisms.
Donal Manahan, University of Southern California.

This international, advanced-level, graduate training course will be organized and taught in Antarctica for one month during the austral summer of 2000-2001. The course introduces students to the diversity of biological organisms in the Antarctic and allows them to study unique aspects of biology that permit life in such extreme environments.

Long-standing questions in evolution and ecology about the biology of antarctic organisms (such as cold adaptation and food limitation) are examined through physiological experiments with organisms, studies of isolated cells and tissues, experiments on protein structure and function, and molecular analysis of genetics systems. Lectures from ten instructors emphasize physiological, biochemical, and molecular biological approaches to understanding the ecology and biological adaptations of antarctic organisms, with exposure to field collection techniques. Specific themes for the 2001 course include biodiversity and molecular phylogeny; energy metabolism; macromolecular synthesis; membrane physiology; temperature adaptation; and UV-photobiology.

Student research projects follow these interwoven themes. The students should gain a rigorous understanding of the power - as well as the limitations - of the physiological, biochemical, and molecular biological methods that are currently being used to answer research questions in environmental science and the biology of adaptation. The course will be held in the Crary Science and Engineering Center at McMurdo Station, Antarctica. This modern research facility provides state-of-the-art laboratory facilities a short distance from the marine and freshwater environments where biological observations are made and material is collected.

By attracting an extremely competitive group of two dozen young scientists, students, and postdoctoral researchers, this course introduces new researchers to Antarctica and teaches students the modern research methods currently being deployed to study mechanisms that are unique to biology in Antarctica. (BO-301-O)

Bentho-pelagic coupling on the west Antarctic Peninsula shelf: The impact and fate of bloom material at the seafloor.
Craig R Smith, University of Hawaii Manoa, and David DeMaster, North Carolina State University.

Primary production in antarctic coastal waters is highly seasonal; each spring/summer, an intense pulse of biogenic particles is delivered to the floor of the continental shelf. This seasonal pulse may have major ramifications for carbon cycling, benthic (seafloor) ecology and the nature of material buried on the west Antarctic Peninsula (WAP) shelf. This project brings several disciplines together in an effort to evaluate the bloom material - its fate, accumulation on the seafloor, and impact on the benthic community.

We will work along a transect of three stations crossing the antarctic shelf in the Palmer Long Term Ecological Research (LTER) study area. We plan to complete a series of five cruises during the 2000-2001 research season, and continue to test the following hypotheses:

• A substantial proportion of spring/summer export production is deposited on the WAP shelf as phytodetritus or fecal pellets.

• The deposited bloom production is a source of labile particulate organic carbon (POC) for bottom-dwelling organisms (benthos) for a time period of months.

• Large amounts of labile bloom POC are rapidly subducted into the sediment column by the deposit-feeding and caching activities of benthos.

• Macrobenthic detritivores undergo rapid increase in numbers and biomass following the spring/summer POC pulse.

To test these hypotheses, we will evaluate seabed deposition and POC lability, patterns of POC mixing into sediments, seasonal variations in macrofaunal and megafaunal abundance, biomass and reproductive condition, and rates of POC and silica mineralization and accumulation in the seabed. We will contrast the fluxes of biogenic materials and radionuclides (into midwater particle traps) with seabed deposition and burial rates (observed through time-lapse photography); this data should permit us to establish water-column and seabed preservation efficiencies for these materials.

A better understanding of the spring/summer production pulse on the WAP shelf should enhance our understanding of carbon cycling in Antarctic coastal systems, as well as the impact of such fluctuations on the seafloor communities.(BO-303-O)

Control of denitrification in a permanently ice covered antarctic lake: Potential for regulation by bioactive metals.
Bess B. Ward, Princeton University.

Denitrification driven by bacteria is the process by which nitrogen is lost from ecosystems. As such, the rate and regulation of denitrification may directly affect both primary biological production and carbon cycling, over both short and long time scales. This research investigates a natural experimental system to be found in the permanently ice-covered Lake Bonney in the Taylor Valley of East Antarctica to ask: What is the role of bioactive metals in regulating denitrification?

Lake Bonney has two distinct lobes, but in only one does denitrification occur. Previous study has ruled out most of the obvious biological and chemical variables - which usually influence denitrification - that might account for the difference between the two lobes. Denitrifiying bacteria are present in both lobes of the lake, where tests of both temperature and salinity reveal conditions they can thrive in. Thus, a paradox: Despite apparently favorable conditions, what is inhibiting denitrification in one lobe and not the other?

Our study entails a combination of culture experiments and field work to examine this paradox. Specifically, we will be:

• experimenting with the denitrifying isolates to determine metal tolerances and requirements for growth;

• measuring metal concentrations and metal speciation in surface transects and depth profiles; and

• probing how denitrifying bacteria respond to alterations in the availability of certain metals.

By elucidating the relationship between microbial activity and metal distributions in Lake Bonney, we hope to add to scientific knowledge about the cycling of elements in other aquatic systems. We also expect to develop insights useful for evaluating the proposed use of paleo-denitrification indicators for past-climate reconstructions. Finally this research may shed light on the potential significance of the ratio of global marine denitrification/nitrogen fixation to atmospheric carbon-dioxide levels. (BO-310-O)

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