Biology and medical research
Photochemical and optical properties of antarctic waters in response to changing ultraviolet-B radiation. Kenneth Mopper, Washington State University, and David Kieber, State University of New York. The decrease in stratospheric ozone over the Antarctic results in an increase in the ultraviolet-B (UV-B) flux in the euphotic zone. The increase leads to cellular damage to aquatic organisms, as documented by photoinhibition and decreased productivity. Cellular damage can occur either intracellularly or externally at the cell surface from biomolecular reactions with externally generated reactive transients. The extent of this extracellular damage will depend on the photochemistry of the seawater surrounding the cell. Until recently, nothing was known about the type of photochemical processes, rates, and steady-state concentrations of transients in antarctic waters.
Our field experiments will allow the construction of predictive models of photochemical production rates in surface waters and with depth. These studies will involve further quantum yield measurements, development of a sensitive underwater actinometer system, and use of a new underwater multichannel photometer. The model will allow the prediction of the impact of varying levels of UV-B on the photoproduction and steady-state concentration of several key reactive transient species in the upper water column. In addition to this effort, experiments will also be performed to study the photodegradation of dissolved organic matter and to determine whether biologically utilizable substrates that are formed photochemically can enhance secondary productivity in antarctic waters. (BO-002-A and BO-002-B)
Impacts of climate change on antarctic vascular plants: Warming and ultraviolet-B radiation. Thomas Day, Arizona State University. Evidence is strong that the climate of the Antarctic Peninsula has changed appreciably in this century. Weather records indicate that mean summer air temperatures have risen more than 1° C over the past 45 years at some peninsula locations. In addition to this warming trend, springtime ozone depletion events have resulted in well-documented increases in ultraviolet-B (UV-B) radiation levels. These rapid changes in regional climate provide a unique opportunity to assess the impacts of climate change on vascular plants.
Although the presence of only two native vascular plant species (Deschampsia antarctica and Colobanthus quitensis) and their sparse distribution in Antarctica attest to the severe conditions for plant survival, there are already indications that climate changes are exerting a strong influence on these species. Regional warming appears to be leading to rapid increases in populations of these species, based on censuses taken along the peninsula. The influence of enhanced UV-B levels on these species is less clear.
An experiment has been initiated in which temperature and UV radiation levels are manipulated around naturally growing Deschampsia and Colobanthus plants on the Antarctic Peninsula to assess their responses to these factors. Assessment involves examining changes in photosynthesis, growth, and reproduction of these plants following warming or exclusion of different UV components.
During the first two field seasons, growth significantly improved under warming treatments. Although exclusion of UV did not have any significant effects over the first field season, over the second field season, exclusion of UV improved vegetative growth, and it appears that levels of UV in Antarctica can reduce leaf elongation as well as leaf production in native plants. Field manipulations will be continued and expanded in the current assessment of plant responses in four key areas: photosynthesis, general thermal adaptations, reproduction, and soils. These areas are critical to understanding plant responses to climate change in Antarctica. (BO-003-O)
LEXEN: Biology and ecology of South Pole snow microbes. Edward J. Carpenter, State University of New York at Stony Brook. Scientists have always assumed that the interior ice sheets of the continent of Antarctica are devoid of indigenous organisms. Although plants, protozoa, and bacteria are present at the fringes of the continent, the combination of low temperatures, long periods of darkness, and the absence of liquid water makes the interior extremely hostile to life.
Recent examination of snow from the South Pole, however, indicates the presence of microbes that contain DNA and photosynthetic pigments. Snow samples were collected at Amundsen–Scott South Pole Station in January 1997 and flown immediately to the Crary Laboratory at McMurdo Base. Examination of snowmelt using epifluorescence microscopy showed the presence of rod-shaped particles approximately 1´ 2.5 micrometers in size and a concentration of 130 (standard deviation = 64) cells per milliliter. The particles fluoresced orange under blue excitation light and reddish-orange under green excitation, indicating the presence of phycobiliproteins and chlorophyll. These fluorescence signatures, combined with the particles' shape, suggest that they are cyanobacteria. Subsequent analysis using fluorescent DNA stains and scanning electron microscopy confirmed the presence of DNA-containing microbes identical in shape to the autofluorescing particles seen with epifluorescent microscopy.
Further research will confirm whether these microbes are indigenous to the antarctic interior and will investigate their biology and ecology. The discovery of organisms capable of survival in interior Antarctica would provide us with new insight into the adaptability of life. Their biomolecules and metabolism must be unique and could have great value for molecular engineering research. (BO-004-O)
Role of antifreeze proteins in freezing avoidance in antarctic fishes: Ecological and organismal physiology, structure-function and mechanism, genetics, and evolution. Arthur DeVries, University of Illinois. Ongoing and new studies of the role of antifreeze glycopeptides (AFGPs) and peptides (AFPs) in freezing avoidance of antarctic fishes in five specific areas constitute this project:
The extent of exogenous and endogenous ice will be determined for McMurdo area fishes, which experience the coldest and most ice-laden waters of the antarctic region. Similar experiments will be conducted for the less severe marine environment of the Antarctic Peninsula. These studies will correlate freezing extremes with circulating levels of AFGPs in the fishes associated with these two environments. (BO-005-M)
The Polar T3 Syndrome: Metabolic and cognitive manifestations, their hormonal regulation and impact upon performance. H. Lester Reed, H.M. Jackson Foundation for Military Medicine. People who live and work in Antarctica for longer than 4 to 5 months develop a characteristic constellation of symptoms and hormonal changes called the Polar T3 Syndrome. These people have previously been described as having a 40 percent increase in energy requirement; frequent mood disorders; doubling of the production, utilization, and tissue stores of the most active thyroid hormone, triiodothyronine (T3); a decline in central nervous system thyroxine (T4); and acquisition of physiologic cold adaptation.
Over a 4-year period, we are studying these apparent discordant and compartmentalized tissue responses using a multidisciplinary approach carried out by experienced polar physiologists, endocrinologists, and psychologists. We are examining the possible cognitive and metabolic changes in performance from declines in central nervous system T4 and elevations in skeletal muscle T3 content. We use placebo-controlled T4 replacement directed at the central nervous system deficit and measure with cognitive instruments. T3 content within the cardiovascular system is evaluated by using submaximal exercise testing to differentiate resting from activity-mediated energy-use contributions by the skeletal muscles. Additionally, tissue samples of skeletal muscle provide information regarding the genetic coding for T3 responsive proteins to help better characterize the thyroid status of these muscles. Moderate energy restriction is used along with T4 supplementation to study the dependence of T3 production, distribution, and tissue stores upon both pituitary generation of thyrotropin and energy intake. We compare each subject's baseline in the predeployment situation of California to periods and standardized measures obtained during the antarctic summer and winter.
We believe that a correction of the low T4 state in the central nervous system can be managed with T4 supplementation without dramatically changing energy requirements as suggested by previous human studies using cold air chamber experiments. If this thesis is correct, then characteristic declines in mood and memory during winter seasons in circumpolar regions may be attenuated by T4 supplementation without disadvantageous effects upon their energy metabolism. Additionally, this project will expand information regarding the ultimate regulation and maintenance of the increased T3 production, which is a central determinant of the Polar T3 Syndrome. (BO-008-O)
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 is found in regions of pack ice or fast ice close to the antarctic continent. This species has been the focus for long-term population studies in McMurdo Sound since the mid-1960s. This data set, one of the few of its kind in the world, has provided valuable knowledge leading to an understanding of the survival and reproductive patterns of a long-lived vertebrate.
Using recently developed molecular biology techniques, we will examine the breeding system and reproductive fitness. By examining the behavioral ecology and mating system through paternity analysis of breeding males, we will be able to estimate reproductive success and effective population size in this aquatic breeding species. A second aspect of the study will examine population demographics (which is a continuation of the annual analyses), parameter estimation, and hypothesis testing associated with the existing 30-year database. As part of this second aspect, a comprehensive analysis of the population dynamics will focus on the role that immigration and emigration play in the population dynamics.
As the southernmost breeding mammal in the world, the Weddell seal exemplifies an extreme in environmental adaptability. Understanding the strategies seals employ in this environment will contribute to the basic understanding of pinniped evolution and population dynamics and competition in marine mammals. (BO-009-O)
New approaches to measuring and understanding the effects of ultraviolet radiation on photosynthesis by antarctic phytoplankton. Patrick Neale, Smithsonian Institution. Increases in ultraviolet-B radiation (UV-B, 280-320 nanometers) associated with the antarctic ozone hole have been shown to inhibit the photosynthesis of phytoplankton, but the overall effect on water column production is still a matter of debate and continued investigation. Investigations have also revealed that even at "normal" levels of antarctic stratospheric ozone, UV-B and UV-A (320-400 nanometers) appear to have strong effects on water column production. The role of UV in the ecology of phytoplankton primary production has probably been underappreciated in the past and could be particularly important to the estimation of primary production in the presence of vertical mixing. We will quantify UV effects on photosynthesis of antarctic phytoplankton by defining biological weighting functions for UV-inhibition.
We will use new theoretical and experimental approaches to investigate UV responses in both the open waters of the Weddell-Scotia confluence and coastal waters near Palmer Station. In particular, we will measure the kinetics of UV inhibition and recovery on timescales ranging from minutes to days. Variability in biological weighting functions will be calculated for pelagic and coastal phytoplankton in the Southern Ocean. Our results will
The role and regulation of chloride cells in antarctic fish. David Petzel, Creighton University. Antarctic fish have the highest serum osmolality of any seawater teleost. Maintenance of fluid balance is crucial for survival. Upon warm acclimation from -1.5° to 4° C, the fish lose 20 percent of their serum osmolality through extrusion of sodium chloride (NaCl) across the gill. NaCl extrusion in fish is primarily performed by chloride-secreting cells located on the gill arches and gill opercula. The driving force for NaCl transport is the sodium/potassium-ATPase. To date, no inormation is available concerning the role and regulation of the elevated serum osmolarity in antarctic fish. Questions that arise include these:
We will compare the chloride cell physiology and regulation in antarctic fish with a New Zealand fish that is eurythermal. We hope to determine the plasticity of antarctic and New Zealand fish gill function at the physiological level (through studies of ion transport activity) and molecular level (through studies of the sodium/potassium-ATPase enzyme). Specifically, this research will
The results of our research will, for the first time, describe in detail the underlying mechanism(s) mediating the enhanced hypo-osmoregulation observed in antarctic fish and will allow the comparison of these results to those observed in a eurythermal New Zealand fish. (BO-012-O)
Weddell seal foraging: Behavioral and energetic strategies for hunting beneath the antarctic fast ice. Randall Davis, Texas A&M University at Galveston. To forage efficiently beneath the extensive, unbroken fast ice along the antarctic coast, Weddell seals (Leptonychotes weddellii) have adapted to an environment that is very challenging for an air-breathing predator. These adaptations enable Weddell seals to hunt for prey at depth while holding their breath for 20 minutes or longer. This feat is analogous to a lion or other large terrestrial predator holding its breath while it locates, pursues, and captures prey. In addition, Weddell seals must return to the same hole at the end of a dive or know the location of other breathing holes. Failure to locate a breathing hole will result in a seal's death by drowning.
We will investigate the behavioral and energetic adaptations that enable Weddell seals to forage in the antarctic fast-ice environment. To achieve this goal, we will measure the underwater behavior, locomotor performance (swimming velocity, stroke frequency and amplitude, and three-dimensional movements), and energy metabolism of Weddell seals during foraging dives. We will test hypotheses on general foraging strategies, searching behavior, searching mechanics, modes of swimming, metabolic costs of foraging, and foraging efficiency for different environmental conditions and prey type. Until now, it has not been possible to investigate the foraging behavior of marine mammals in detail. To accomplish this study, we will attach a small video system and data logger to the seals' backs and measure oxygen consumption during voluntary dives from an isolated ice hole in McMurdo Sound, Antarctica.
Observing the foraging behavior and prey of marine mammals has been and continues to be a major obstacle to the advancement of studies on their foraging ecology. The Weddell seal may be the single best species in which to study the foraging behavior and energetics of deep-diving pinnipeds because
Impacts of increased solar ultraviolet-B radiation on antarctic marine heterotrophs. H. William Detrich, III, and Kirk D. Malloy, Northeastern University. Recent decreases in stratospheric ozone have resulted in dramatic increases in the flux of mid-ultraviolet light (UVB) reaching the Earth's surface, especially over Antarctica but, to a lesser extent, in temperate zones. Ozone depletion is expected to continue well into the next century and to worsen at lower latitudes over time. Recent evidence suggests that present intensities of UVB are sufficient to produce significant impacts on phytoplankton communities in the Southern Ocean, as well as to negatively affect tropical marine communities and populations of temperate amphibians. The abbreviated trophic structure of the antarctic marine ecosystem places an increased importance on primary and secondary consumers, especially on many species of zooplankton, which form a critical link between primary production and top predators such as adult fish, marine mammals, and birds. Although these zooplankton species and other heterotrophs, which include larval and adult fish, krill, and copepods, are important components of the trophic structure in the antarctic ecosystem, researchers have no information regarding the effects of increased UVB on natural populations of these organisms. Laboratory and field studies on nonpolar species suggest, however, that the impact of increased UV on antarctic heterotrophs, and therefore on the antarctic ecosystem, could be substantial.
Using established methods, we will
The field component of this research is a unique effort to determine the in situ vulnerability of natural populations of antarctic heterotrophs during normal and depleted ozone conditions. These studies are critical for developing predictive models of the relative impact of increased UVB on antarctic marine heterotrophs and for relating ozone depletion on decreased fitness, survival, and population dynamics of these species. (BO-029-O)
Factors regulating population size and colony distribution of Adélie penguins in the Ross Sea. David G. Ainley, H.T. Harvey and Associates. In this collaborative project, we will investigate the demographic mechanisms responsible for dramatic growth in existing Adélie penguins (Pygoscelis adeliae) colonies over the past few decades. We will also investigate the possibility that growth is related to documented climate change in the region by
This will be the first empirical study to consider the geographic structuring of a seabird population. Results will increase understanding of
In addition, results will provide a context in which to interpret conflicting data on penguin population trends from existing programs that use Adélie penguins as an indicator species for point-source anthropogenic impact on antarctic resources (e.g., fishery catches, disturbance by tourism).
Our 5 years of research (3 full years funded by the National Science Foundation) include intensive field study conducted at three Ross Island penguin colonies. 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). Methods will bring together several well-established techniques that have been successfully but infrequently used in antarctic biological research:
Our research builds on, and collaborates with, the efforts of Landcare Research New Zealand (LCRNZ), which has conducted two preliminary field seasons, including testing of new equipment, and will continue their effort and 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, and Beigel Technology, will collaborate with those from H.T. Harvey and Associates and LCRNZ to accomplish project goals. (BO-031-O)
Evolution of an oxygen-binding hemoprotein in a unique environment: Myoglobin in the hemoglobinless antarctic icefishes. Bruce D. Sidell, University of Maine at Orono. For approximately the last 40 million years, a unique fish fauna has been evolving in the frigid seas surrounding Antarctica. Physiological function of these water-breathing animals has demanded many adaptations to ensure proper metabolism and regulation of biochemical processes at cell temperatures of about 0° C. Among the polar fishes, one family is particularly unusual: the Channichthyid icefishes. Species in this family lack hemoglobin in their circulating blood and, at least the majority, do not possess the intracellular respiratory protein, myoglobin, that is normally responsible for enhancing movement of oxygen through aerobic muscle tissues. Recently, however, two species of icefish that express myoglobin, Pseudochaenichthys georgianus and Chionodraco rastrospinosus, have been found, but these species express myoglobin in only one tissue—heart ventricle. The metabolism of all icefish species is highly aerobic and is based largely on the combustion of fatty fuels as energy sources.
Our fieldwork will consist of a combination of shipboard trawling to capture icefish species and laboratory work at Palmer Station using tissues from these animals. At Palmer Station, we will conduct experiments and prepare purified, fixed, and/or frozen material for shipment back to the United States for further analyses. The overall goals of this project are
Structure, function, and expression of cold-adapted tubulins and microtubule-dependent motors from antarctic fishes. H. William Detrich, III, Northeastern University. Microtubules, which are subcellular "pipelike" filaments composed of the protein tubulin, and their associated motors, dynein and kinesin, participate in many fundamental cellular processes, including cell division, nerve growth and regeneration, cell motility, and the organization and transport of organelles within cells. In these processes, microtubules serve as rigid "railroad tracks" for the movement of motors and their cargoes ("trains"), and the motors themselves are 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, at the molecular level, the adaptations that enhance the assembly of microtubules, the expression of tubulin genes, and the activity of microtubule motors from antarctic fishes in this extreme thermal regime. Our objectives are
We will determine molecular adaptations of the antarctic fish tubulins by comparing the amino acid sequences of alpha- and beta-tubulins from N. coriiceps, to those from its temperate relative, the New Zealand black cod, Notothenia angustata. We will analyze gene expression in N. coriiceps by defining the organization and transcription-regulating elements of an alpha-tubulin gene cluster. In the broadest sense, this research should advance the molecular understanding of the cold-adapted mode of life. (BO-037)
Penguin-krill-ice interactions: The impact of environmental variability on penguin demography. Wayne Trivelpiece, Montana State University. We will study populations of Adélie, gentoo, and chinstrap penguins at Admiralty Bay, King George Island. These populations have exhibited fluctuations in abundance that have been related to long-term changes in environmental conditions, in particular sea-ice coverage and its possible effects on prey (krill) availability.
We will test the following five hypotheses relating penguin demography to environmental variability via its effect on krill recruitment in the antarctic marine ecosystem.
The Pygoscelis species, the major predators of krill (Euphausia superba) in the Antarctic Peninsula region, are key species used to monitor the potential impacts of fishery activities in this area. To understand the structure and function of the antarctic marine ecosystem thoroughly, it is imperative to determine the impact of environmental variation on the structure and regulation of upper trophic level predators such as the Pygoscelis penguins. (BO-040-O)
Shell morphogenesis in giant agglutinated foraminifera. Samuel S. Bowser and Charles R. Hauer, Health Research, Inc. A dominant member of cold, deep-sea sediments ecosystem is a group of giant protozoa, the aggulatinated foraminifera, also known as forams. For protection, these single-celled organisms encase themselves in architecturally elegant shells that they construct by collecting, sorting, and cementing together sediment grains. The unique occurrence of these giant cells (greater than 1 millimeter in size) in the shallow waters of McMurdo Sound, Antarctica, allows for the study of the cellular and molecular aspects of shell constructions.
In our project, we will use novel light-microscopic methods to examine how agglutinated forams secrete and sculpt the adhesive matrix that binds sediment particulate in their shells. Comparative time-lapse photography of different foram species constructing shells will identify key steps in the processes that lead to the various shell morphologies. Peptide sequence analyses of the elastic proteins of the shells will provide valuable insight into the chemical nature of foram bioadhesives. From a practical standpoint, these cements have important biotechnological and medical applications.
We will also continue a study of the effects of collection activities, as well as natural physical disturbances, in this unique environment. The interdisciplinary research conducted for this project has implications in a number of fields, including cellular development, evolution, paleontology, marine products chemistry, and ecosystem management. (BO-043-O)
LEXEN: Microbial life within the extreme environment posed by permanent antarctic lake ice. Christian H. Fritsen, Edward E. Adams, James A. Raymond, John C. Priscu, and Christopher P. McKay, Montana State University. The 3- to 20-meter-thick permanent ice covers on lakes in the McMurdo Dry Valleys, Antarctica, contain viable microbial cells in association with sediment aggregates. These aggregates are now recognized as sites where physical, chemical, and biological interactions promote microbial growth under extreme conditions inherent to the ice environment.
In this interdisciplinary research program, we will define specific processes that allow
We will study ice aggregates embedded in the permanent ice covers on the lakes in the Taylor Valley, which have been tentatively characterized in previous studies.
Research on microbes in permanent ice provides information on the ecology of microbes in ice ecosystems and promises to have biotechnological implications. Furthermore, these studies will provide insights into the conditions that support or have supported life beyond our own planet in association with water ice, which has been detected within and beyond our own solar system. (BO-044-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—cause primary production to fluctuate extensively and to affect strongly the pelagic and benthic communities. We will initiate a long time-series study of the water column and seafloor using long-term, autonomous monitoring and sampling systems developed for use in the Antarctic. Our study will be located in Post Foster, Deception Island, which supports a pelagic and benthic fauna representative of the antarctic coastal zone and experiences seasonal ice cover.
We will deploy a bottom-moored, upward-looking acoustic instrument on the seafloor for 1 year 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. The instrumentation development 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 on the distribution, abundance, size, and movements of the epibenthic megafauna will be addressed. Results from this study will provide a valuable database for the evaluation of the pelagic and benthic community responses to seasonal variability in the Southern Ocean. (BO-050-O)
Adaptations of organisms at the sulfide- and methane-containing hydrothermal areas of Deception Island, Antarctica. Horst Felbeck, Scripps Institution of Oceanography. Deception Island is a flooded caldera in the South Shetland Islands, Antarctica. The most recent eruption, in the 1970s, caused the formation of new islands in the caldera and various other structures. Deception Island harbors many hot springs and fumaroles submerged in the caldera and intertidally. Sulfide and methane are prominent chemicals in the outflowing waters. Bacterial densities in the caldera reach unusually high values probably due to the input of reduced chemicals as energy sources. The environment around the springs resembles that found at hydrothermal vents where whole communities are based on the input of chemical energy by the hot waters. Similarities to hydrothermal vent environments include cold waters surrounding the hot springs resulting in large distances to the next warm-water habitat and a lack of external food sources. The latter is due to ice cover during winter at Deception Island and the large distance to the euphotic zone at the vent sites. These parameters encourage the evolution of alternative ways to support life such as the establishment of a bacterial symbiosis.
In this project, we will examine the warm springs around Deception Island for the presence of marine invertebrates with chemoautotrophic symbionts. We will map any submerged fumaroles as well as warm and hot springs in the intertidal zone. If animals are found near the fumaroles or in the hot springs, we will collect specimens and examine them for the presence of chemoautotrophic bacteria and other adaptations to a hot sulfide- and methane-rich environment using enzyme test experimental incubations to analyze metabolic pathways and microscopic examination. (BO-085-O)
Biological baselines and responses for assessing environmental impacts in antarctic coastal areas. Paul Berkman, Ohio State University. Antarctic coastal environments have been the site of recent studies on the effects of human activities on marine ecosystems. This international, collaborative study will develop methodologies to generate biological baselines for the benthic nearshore habitat in the Ross Sea region of Antarctica. These baselines will be useful in distinguishing between natural environmental variability from anthropogenic impacts and in assessing the recovery capacity of coastal marine populations that have been exposed to natural and anthropogenic stresses.
Our study, which will take place in Terra Nova Bay, will be conducted in cooperation with the Italian Antarctic Program. We will study populations of the scallop Adamussium colbecki from a natural-impact site (meltwater stream), an anthropogenic-impact site (near Terra Nova Bay Station in Tethys Bay), and a control site (no meltwater stream in a pristine area of Tethys Bay). Integration of biochemical, physiological, and population assays will provide examples of biological baselines for assessing indicator species' responses to natural and anthropogenic impacts in the antarctic coastal zone. (BO-086-O)
Ultraviolet-radiation-induced DNA damage in bacterioplankton in the Southern Ocean. Wade H. Jeffrey, University of West Florida. Strong evidence now shows that ultraviolet (UV) radiation is increasing over certain locations in Antarctica and the Southern Ocean as a result of ozone depletion. A reduction in ozone concentration selectively limits stratospheric adsorption of UV radiation and results in a higher UV irradiance reaching the Earth's surface. Although research on the impact of increased UV radiation due to ozone depletion has focused primarily on phytoplankton, a much smaller effort is being directed to other trophic levels.
During this collaborative project, we will address UV-radiation-induced damage and UV-radiation effects on bacterioplankton. We will examine interactions between bacterioplankton and photochemical processes and interactions with higher trophic groups such as phytoplankton and zooplankton. We will address these topics:
We will elucidate the molecular determinants responsible for changes in productivity and the molecular and physiological responses to changing UV radiation. The overall goal is to provide a greater understanding of the potential impact that changes in UV radiation have on marine microbial communities. (BO-200-O)
LEXEN: Protistan biodiversity in antarctic marine ecosystems: Molecular biological and traditional approaches. David A. Caron and Rebecca J. Gast, Woods Hole Oceanographic Institution. The analysis of microbial biodiversity of extreme environments is difficult because traditional methods for examining diversity are often ineffective for assessing species richness within these communities. Additional obstacles arise because of the difficulties of recreating and maintaining pertinent environmental features during sample collection and procession.
We will study the protistan assemblages (algae and protozoa) in the sea-ice, sediment, and ocean environments of the Ross Sea, Antarctica. The identification of protistan species in natural assemblages traditionally has entailed direct microscopical analyses as well as enrichment and culture techniques for assessing biodiversity. Determining diversity for these assemblages is, therefore, susceptible to biases as a consequence of sampling, enrichment, and culture, as well as selective losses due to sample preservation and concentration for microscopy.
Our goals are
As part of our molecular biological studies, we will examine small subunit ribosomal RNA gene (srDNA) diversity. Approaches and techniques developed will be applicable to any other water body or sediment and would provide a means to examine the representativeness of protistan cultures in extant culture collections. (BO-207-O)
The role of oceanographic features and prey distribution on foraging energetics and reproductive success. Daniel Costa, University of California at Santa Cruz. Marine coastal and pelagic environments of the Southern Ocean are characterized by seasonal high productivity. Over the last several decades, it has become clear that these environments, although generally productive, also undergo considerable inter- and intra-annual variability. Consequently, available prey resources for vertebrate predators can be highly variable spatially and temporally.
This spatial and temporal variability of prey resources has been measured empirically for the northern South Shetland Islands region of the Antarctic Peninsula since the late 1980s. The antarctic fur seal, a subpolar migratory otariid with a short lactation period, is an increasingly dominant marine predator of the South Shetlands region. Its life-history pattern is characterized by foraging trips alternating with short visits to provide for a single offspring; this pattern allows scientists to measure maternal investment on the same temporal and spatial scale as measurements of distribution and abundance of prey.
In our project, we will quantify the foraging costs and maternal investment associated with changes in strategies observed in populations of South Shetland antarctic fur seals. Using state-of-the-art techniques, we will determine energetic costs and benefits of different foraging patterns while simultaneously measuring energy expenditure, food intake, dive depth, dive duration, time of day, and 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 is also contributing to the support of this project. The research will allow scientists to link biological characteristics (prey composition, distribution, and abundance) and physical characteristics of the foraging environment with foraging success, maternal investment, and reproductive success for a free-ranging marine vertebrate predator. (BO-267-O)
Characterization of indigenous and introduced toxic phytoplankton in Antarctica. Donald Anderson, Woods Hole Oceanographic Institution. Of the thousands of species of marine phytoplankton, only a few produce potent toxins. These species are found in the massive "red tides" or blooms of cells that discolor the water. More commonly, the organisms are present at low concentrations and are noticed only by the effects their toxins have on aquatic organisms and humans. The nature of the toxic phytoplankton problem has changed considerably in recent years: many areas that were previously unaffected are now subject to recurrent outbreaks. Therefore, it is alarming that marine algal toxins (saxitoxins) have been found in antarctic mollusks.
The implications of this discovery are profound given the low number of trophic levels between primary producers and top predators and the proven ability of the saxitoxins to alter the food web structure and dynamics. Saxitoxins can affect zooplankton, fish larvae, whales, porpoises, seabirds, and humans. Researchers are concerned that the saxitoxin-producing alga, presumably the dinoflagellates in the genus Alexandrium, has been introduced to antarctic waters, possibly by vessel traffic between South America and the Antarctic Peninsula. This mechanism of species dispersal has been implicated in the sudden appearance of toxic algae in other areas of the world. Short and frequent transport pathways do exist between Antarctica and the high-toxicity waters of southern Chile and Argentina. It is also possible that the saxitoxin-producing organism is indigenous to Antarctica and was only recently noticed. In either case, the implications to the antarctic food web are significant.
The objectives of our project are to identify and characterize the possible source(s) of saxitoxins in Antarctica to determine whether the causative organisms are indigenous or introduced species, and if introduced, to identify the probable origin and transport pathway. (BO-300-O)
1998–1999 McMurdo Station biology course. Donal Manahan, University of Southern California. This international, advanced-level, graduate training course will be organized and taught in Antarctica for 1 month during austral summer 1998–1999. The course will introduce students to the diversity of biological organisms in antarctic regions and allow them to study unique aspects of biology that permit life in such extreme environments. Long-standing questions in evolution and ecology (such as cold adaptation and food limitation) concerning the biology of antarctic organisms will be 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 will emphasize physiological, biochemical, and molecular biological approaches to understanding the ecology and biological adaptations of antarctic organisms. Student research projects will follow these interwoven themes. The students will gain a rigorous understanding of the power, but also the limitations, of physiological, biochemical, and molecular biological methods that are currently being used to answer research questions in environmental science and biological 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 and collections of material will be made. The course will be taught as four modules:
By attracting an extremely competitive group of young scientists, this course will introduce new researchers to Antarctica and will teach students to use modern research methods to study the mechanisms that are unique to biology in Antarctica. (BO-301-O).
Viruses in pack-ice communities of the Ross Sea, Antarctica. Marcia M. Gowing, University of California at Santa Cruz. Primary productivity of sea-ice algal communities in the Southern Ocean is significant. In lower latitudes, processes such as grazing and destruction by viruses are thought to control algal populations, but science has little data on grazing within ice communities and no data on viruses of ice algae. Ice communities should be excellent sites for studying viral control of populations of eukaryotic algae and protozoans because populations are extremely dense and many habitats are nearly closed for parts of the year.
We will use transmission electron microscopy (TEM) of individual eukaryotic algal and protozoan cells and light microscopy and TEM of water samples to assess viral infections and viral populations in a variety of pack-ice communities from the Ross Sea. Our objectives are
Our study will contribute to the understanding of sea-ice community ecology and will allow us to incorporate viruses of eukaryotic algae and protozoans into models of carbon flow for the Antarctic. (BX-039-O)
Ecological studies of sea-ice communities in the Ross Sea, Antarctica. Marcia M. Gowing, University of California at Santa Cruz. Sea ice forms an extensive habitat in the Southern Ocean. Reports dating from the earliest explorations of Antarctica have described high concentrations of algae associated with sea-ice, suggesting that the ice must be an important site of production and biological activity. The magnitude and importance of ice-based production are difficult to estimate largely because the spatial and temporal distributions of ice communities have been examined in only a few regions, and the processes controlling production and community development in ice are still only superficially understood.
We will examine sea-ice communities in the Ross Sea region of Antarctica in conjunction with studies of ice physics and remote sensing. The specific objectives of our study are