Antarctic notothenioid fishes exhibit two adaptive traits to survive in frigid temperatures. The first of these is the production of anti-freeze proteins in their blood and tissues. The second is a system-wide ability to perform cellular and physiological functions at extremely cold temperatures.The proposal goals are to show how Antarctic fishes use these characteristics to avoid freezing, and which additional genes are turned on, or suppressed in order for these fishes to maintain normal physiological function in extreme cold temperatures. Progressively colder habitats are encountered in the high latitude McMurdo Sound and Ross Shelf region, along with somewhat milder near?shore water environments in the Western Antarctic Peninsula (WAP). By quantifying the extent of ice crystals invading and lodging in the spleen, the percentage of McMurdo Sound fish during austral summer (Oct-Feb) will be compared to the WAP intertidal fish during austral winter (Jul-Sep) to demonstrate their capability and extent of freeze avoidance. Resistance to ice entry in surface epithelia (e.g. skin, gill and intestinal lining) is another expression of the adaptation of these fish to otherwise lethally freezing conditions.<br/><br/>The adaptive nature of a uniquely characteristic polar genome will be explored by the study of the transcriptome (the set of expressed RNA transcripts that constitutes the precursor to set of proteins expressed by an entire genome). Three notothenioid species (E.maclovinus, D. Mawsoni and C. aceratus) will be analysed to document evolutionary genetic changes (both gain and loss) shaped by life under extreme chronic cold. A differential gene expression (DGE) study will be carried out on these different species to evaluate evolutionary modification of tissue-wide response to heat challenges. The transcriptomes and other sequencing libraries will contribute to de novo ice-fish genome sequencing efforts.
Abstract<br/>During the Early Pliocene, 4.8 to 3.4 million years ago, warmer-than-present global temperatures resulted in a retreat of the Ross Ice Shelf and West Antarctic Ice Sheet. Understanding changes in ocean dynamics during times of reduced ice volume and increased temperatures in the geologic past will improve the predictive models for these conditions. The primary goal of the proposed research is to develop a new oxygen isotope record of Pliocene oceanographic conditions near the Antarctic continent. Oxygen isotope values from the carbonate tests of benthic foraminifera have become the global standard for paleo-oceanographic studies, but foraminifera are sparse in high-latitude sediment cores. This research will instead make use of oxygen isotope measurements from diatom silica preserved in a marine sediment core from the Ross Sea. The project is the first attempt at using this method and will advance understanding of global ocean dynamics and ice sheet-ocean interactions during the Pliocene. The project will foster the professional development of two early-career scientists and serve as training for graduate and undergraduate student researchers. The PIs will use this project to introduce High School students to polar/oceanographic research, as well as stable isotope geochemistry. Collaboration with teachers via NSTA and Polar Educators International will ensure the implementation of excellent STEM learning activities and curricula for younger students. <br/><br/>Technical Description<br/>This project will produce a high-resolution oxygen isotope record from well-dated diatom rich sediments that have been cross-correlated with global benthic foraminifera oxygen isotope records. Diatom silica frustules deposited during the Early Pliocene and recovered by the ANDRILL Project (AND-1B) provide ideal material for this objective. Diatomite unites in the AND-1B core are nearly pure, with little evidence of opal formation. A diatom oxygen isotope record from this core offers the potential to constrain lingering uncertainties about Ross Sea and Southern Ocean paleoceanography and Antarctic Ice Sheet history during a time of high atmospheric carbon dioxide concentrations. Specifically, oxygen isotope variations will be used to constrain changes in the water temperature and/or freshwater flux in the Pliocene Ross Sea. Diatom species data from the AND-1B core have been used to infer variations in the extent and duration of seasonal sea ice coverage, sea surface temperatures, and mid-water advection onto the continental shelf. However, the diatom oxygen isotope record will provide the first direct measure of water/oxygen isotope values at the Antarctic continental margin during the Pliocene.
The Western Antarctic Peninsula is experiencing climate change at one of the fastest rates of anywhere around the globe. Accelerated climate change is likely to affect the many benthic marine invertebrates that live within narrow temperature windows along the Antarctic Continental Shelf in presently unidentified ways. At present however, there are few data on the physiological consequences of climate change on the sensitive larval stages of cold-water corals, and none on species living in thermal extremes such as polar waters. This project will collect the larvae of the non-seasonal, brooding scleractinian Flabellum impensum to be used in a month-long climate change experiment at Palmer Station. Multidisciplinary techniques will be used to examine larval development and cellular stress using a combination of electron microscopy, flow cytometry, and Inductively Coupled Plasma Mass Spectometry. Data from this project will form the first systematic study of the larval stages of polar cold-water corals, and how these stages are affected by temperature stress at the cellular and developmental level. <br/><br/>Cold-water corals have been shown to be important ecosystem engineers, providing habitat for thousands of associated species, including many that are of commercial importance. Understanding how the larvae of these corals react to warming trends seen today in our oceans will allow researchers to predict future changes in important benthic communities around the globe. Associated education and outreach include: 1) Increasing student participation in polar research by involving postdoctoral and undergraduate students in the field and research program; ii) promotion of K-12 teaching and learning programs by providing information via a research website, Twitter, and in-school talks in the local area; iii) making the data collected available to the wider research community via peer reviewed published literature and iv) reaching a larger public audience through such venues as interviews in the popular media, You Tube and other popular media outlets, and local talks to the general public.
Intellectual Merit: <br/>This project will determine the potential vulnerability of key ice streams to incursions of warmer ocean water onto the continental shelf and if this mechanism could already explain any of the observed thinning of the ice sheet. It will provide important constrains on ice dynamic of the investigated section of the EAIS, and thus will be critical for future ice sheet models and provide mechanisms for EAIS contributions to past sea level high-stand. The PI proposes to investigate four key ice stream systems on the continental shelf between ~90Â°E and 160Â°E. They will use multibeam bathymetry to identify if and where cross-shelf troughs exist to help determine whether these troughs could provide potential pathways for warmer ocean water. Furthermore, detailed analysis of morphological features of these troughs could provide information on past ice dynamic, maximum extent, and flow direction of related paleo ice streams. The PIs will also conduct water column measurements along these troughs and on the continental slope to determine whether warmer ocean water could enter the shelf in the near future, or if such water has already entered any troughs, and thus might be causing the observed thinning of some ice streams.<br/><br/>Broader impacts: <br/>This project includes the participation and support of undergraduate and graduate students in field work and data analysis. The possible involvement of a PolarTREC teacher and the Earth2Class teachers program will reach out to K-12 students.
This proposed research aims to produce high resolution, precise and accurate records of deep water temperatures in the Drake Passage over the past ~40,000 years, by applying the newly developed carbonate clumped isotope thermometer to a unique collection of modern and fossil deep-sea corals, and thus advance the understanding of the role of the Southern Ocean in modulating global climate. In addition, this study will provide further evaluation on the potential of this new thermometer to derive accurate estimates of past ocean temperatures from deep-sea coral skeletons. Funding will support an early-career junior scientist and a graduate student. <br/><br/>Despite its crucial role in modulating global climate, rates and amplitudes of environmental changes in the Southern Ocean are often difficult to constrain. In particular, the knowledge about the deep water temperatures in the Southern Ocean during the last glacial cycle is extremely limited. This results both from the lack of well-dated climate archives for the deep Southern Ocean and from the fact that most existing temperature proxies (e.g. del18O and Mg/Ca of foraminifera and corals) suffer from the biological 'vital effects'. The latter is especially problematic; it causes substantial challenges in interpreting these geochemical proxies and can lead to biases equivalent to tens of degrees in temperature estimates. Recent development of carbonate clumped isotope thermometer, holds new promises for reconstructing deep water temperatures in the Southern Ocean, since calibration studies of this thermometer in deep-sea corals suggest it is largely free of vital effects. This proposed research seeks to refine the calibration of carbonate clumped isotope thermometer in deep-sea corals at low temperatures, improve the experimental methods to obtain high precision in temperature estimates, and then apply this thermometer to a unique collection of modern and fossil deep-sea corals collected from the Drake Passage during two recent Office of Polar Programs (OPP)-funded cruises, that have already been dated by radiocarbon and U-series methods. By combining the reconstructed temperatures with the radiocarbon and U-Th ages for these deep-sea corals, this study will explore the relationships between these temperature changes and global climate changes.
The research will investigate the individual and combined effects of rising ocean acidification and sea surface temperatures on shallow-water calcified benthic organisms in western Antarctic Peninsular (WAP) marine communities. The Southern Ocean is predicted to become undersaturated in terms of both aragonite and calcite within 50 and 100 years, respectively, challenging calcification processes. Adding to the problem, antarctic calcified benthic marine organisms are more vulnerable to ocean acidification than temperate and tropical species because they are generally weakly calcified. Many antarctic organisms are essentially stenothermal, and those in the West Antarctic Peninsula are being subjected to rising seawater temperatures. The project employs both single-species and multi-species level approaches to evaluating the impacts of rising ocean acidification and seawater temperature on representative calcified and non-calcified macroalgae, on calcified and non-calcified mesograzers, and on a calcified macro-grazer, all of which are important ecological players in the rich benthic communities. Multi-species analysis will focus on the diverse assemblage of amphipods and mesogastropods that are associated with dominant macroalgae that collectively play a key role in community dynamics along the WAP. The project will support undergraduate research, both through NSF programs, as well as home university-based programs, some designed to enhance the representation of minorities in the sciences. The principal investigators also will support and foster graduate education through mentoring of graduate students. Through their highly successful UAB IN ANTARCTICA interactive web program, they will continue to involve large numbers of teachers, K-12 students, and other members of the community at large in their scientific endeavors in Antarctica.
The polar ocean presently surrounding Antarctica is the coldest, most thermally stable marine environment on earth. Because oxygen solubility in seawater is inversely proportional to temperature, the cold Antarctic seas are an exceptionally oxygen-rich aquatic habitat. Eight families of a single perciform suborder, the Notothenioidei, dominate the present fish fauna surrounding Antarctica. Notothenioids account for approximately 35% of fish species and 90% of fish biomass south of the Antarctic Polar Front. Radiation of closely related notothenioid species thus has occurred rapidly and under a very unusual set of conditions: relative oceanographic isolation from other faunas due to circumpolar currents and deep ocean trenches surrounding the continent, chronically, severely cold water temperatures, very high oxygen availability, very low levels of niche competition in a Southern Ocean depauperate of species subsequent to a dramatic crash in species diversity of fishes that occurred sometime between the mid-Tertiary and present. These features make Antarctic notothenioid fishes an uniquely attractive group for the study of physiological and biochemical adaptations to cold body temperature. <br/>Few distinctive features of Antarctic fishes are as unique as the pattern of expression of oxygen-binding proteins in one notothenioid family, the Channichthyidae (Antarctic icefishes). All channichthyid icefishes lack the circulating oxygen-binding protein, hemoglobin (Hb); the intracellular oxygen-binding protein, myoglobin (Mb) is not uniformly expressed in species of this family. Both proteins are normally considered essential for adequate delivery of oxygen to aerobically poised tissues of animals. To compensate for the absence of Hb, icefishes have developed large hearts, rapidly circulate a large blood volume and possess elaborate vasculature of larger lumenal diameter than is seen in red-blooded fishes. Loss of Mb expression in oxidative muscles correlates with dramatic elevation in density of mitochondria within the cell, although each individual organelle is less densely packed with respiratory proteins. <br/>Within the framework of oxygen movement, the adaptive significance of greater vascular density and mitochondrial populations is understandable but mechanisms underlying development of these characteristics remain unknown. The answer may lie in another major function of both Hb and Mb, degradation of the ubiquitous bioactive compound, nitric oxide (NO). The research will test the hypothesis that loss of hemoprotein expression in icefishes has resulted in an increase in levels of NO that mediate modification of vascular systems and expansion of mitochondrial populations in oxidative tissues. The objectives of the proposal are to quantify the vascular density of retinas in +Hb and -Hb notothenioid species, to characterize NOS isoforms and catalytic activity in retina and cardiac muscle of Antarctic notothenioid fishes, to evaluate level of expression of downstream factors implicated in angiogenesis (in retinal tissue) and mitochondrial biogenesis (in cardiac muscle), and to determine whether inhibition of NOS in vivo results in regression of angiogenic and mitochondrial biogenic responses in icefishes. Broader impacts range from basic biology, through training of young scientists, to enhanced understanding of clinically relevant biomedical processes.
0538630<br/>Severinghaus<br/>This award supports a project to produce the first record of Kr/N2 in the paleo-atmosphere as measured in air bubbles trapped in ice cores. These measurements may be indicative of past variations in mean ocean temperature. Knowing the mean ocean temperature in the past will give insight into past variations in deep ocean temperature, which remain poorly understood. Deep ocean temperature variations are important for understanding the mechanisms of climate change. Krypton is highly soluble in water, and its solubility varies with temperature, with higher solubilities at colder water temperatures. A colder ocean during the last glacial period would therefore hold more krypton than today's ocean. Because the total amount of krypton in the ocean-atmosphere system is constant, the increase in the krypton inventory in the glacial ocean should cause a resultant decrease in the atmospheric inventory of krypton. The primary goal of this work is to develop the use of Kr/N2 as an indicator of paleo-oceanic mean temperature. This will involve improving the analytical technique for the Kr/N2 measurement itself, and measuring the Kr/N2 in air bubbles in ice from the last glacial maximum (LGM) and the late Holocene in the Vostok and GISP2 ice cores. This provides an estimate of LGM mean ocean temperature change, and allows for a comparison between previous estimates of deep ocean temperature during the LGM. The Vostok ice core is ideal for this purpose because of the absence of melt layers, which compromise the krypton and xenon signal. Another goal is to improve precision on the Xe/N2 measurement, which could serve as a second, independent proxy of ocean temperature change. A mean ocean temperature time series during this transition may help to explain these observations. Additionally, the proposed work will measure the Kr/N2 from marine isotope stage (MIS) 3 in the GISP2 ice core. Knowing the past ocean temperature during MIS 3 will help to constrain sea level estimates during this time period. The broader impacts of the proposed work: are that it will provide the first estimate of the extent and timing of mean ocean temperature change in the past. This will help to constrain previously proposed mechanisms of climate change involving large changes in deep ocean temperature. This project will also support the education of a graduate student. The PI gives interviews and talks to the media and public about climate change, and the work will enhance these outreach activities. Finally, the work will occur during the International Polar Year (IPY), and will underscore the unique importance of the polar regions for understanding the global atmosphere and ocean system.
Patterns of biodiversity, as revealed by basic research in organismal biology, may be derived from ecological and evolutionary processes expressed in unique settings, such as Antarctica. The polar regions and their faunas are commanding increased attention as declining species diversity, environmental change, commercial fisheries, and resource management are now being viewed in a global context. Commercial fishing is known to have a direct and pervasive effect on marine biodiversity, and occurs in the Southern Ocean as far south as the Ross Sea. <br/>The nature of fish biodiversity in the Antarctic is different than in all other ocean shelf areas. Waters of the Antarctic continental shelf are ice covered for most of the year and water temperatures are nearly constant at -1.5 C. In these waters components of the phyletically derived Antarctic clade of Notothenioids dominate fish diversity. In some regions, including the southwestern Ross Sea, Notothenioids are overwhelmingly dominant in terms of number of species, abundance, and biomass. Such dominance by a single taxonomic group is unique among shelf faunas of the world. In the absence of competition from a taxonomically diverse fauna, Notothenioids underwent a habitat or depth related diversification keyed to the utilization of unfilled niches in the water column, especially pelagic or partially pelagic zooplanktivory and piscivory. This has been accomplished in the absence of a swim bladder for buoyancy control. They also may form a special type of adaptive radiation known as a species flock, which is an assemblage of a disproportionately high number of related species that have evolved rapidly within a defined area where most species are endemic. Diversification in buoyancy is the hallmark of the notothenioid radiation. Buoyancy is the feature of notothenioid biology that determines whether a species lives on the substrate, in the water column or both. Buoyancy also influences other key aspects of life history including swimming, feeding and reproduction and thus has implications for the role of the species in the ecosystem. <br/>With similarities to classic evolutionary hot spots, the Antarctic shelf and its Notothenioid radiation merit further exploration. The 2004 "International Collaborative Expedition to collect and study Fish Indigenous to Sub-Antarctic Habitats," or, "ICEFISH," provided a platform for collection of notothenioid fishes from sub-Antarctic waters between South America and Africa, which will be examined in this project. This study will determine buoyancy for samples of all notothenioid species captured during the ICEFISH cruise. This essential aspect of the biology is known for only 19% of the notothenioid fauna. Also, the gross and microscopic anatomy of brains and sense organs of the phyletically basal families Bovichtidae, Eleginopidae, and of the non-Antarctic species of the primarily Antarctic family Nototheniidae will be examined. The fish biodiversity and endemicity in poorly known localities along the ICEFISH cruise track, seamounts and deep trenches will be quantified. Broader impacts include improved information for comprehending and conserving biodiversity, a scientific and societal priority.
Although the cold ocean ecosystems comprise seventy-two percent of the biosphere on Earth by volume, they remain sparsely inhabited and relatively unexploited, particularly in terms of metazoan phyla. Consequently, the few animals that can exist at this border of intracellular freezing represent ideal systems for exploring genomic-level processes of environmental adaptations. Understanding life at a margin of the biosphere is likely to convey significant insights into the essential genomic processes necessary for survival under intense selection pressures. This study of adaptive mechanisms in genomic networks focuses on an experimental system that faces a formidable challenge for viability at low water temperatures: embryonic development at sea water temperatures of -1.8 o C in two Antarctic echinoderms, the sea star Odontaster validus and the sea urchin Sterechinus neumayeri. The project strategy will quantify temperature effects on gene expression and protein turnover networks during early development using a Bayesian network analysis to identify clusters of genes and proteins whose expression levels are associated in fixed, synergistic interactions. Ultimately, there is a simple question to be addressed: Is it more or less difficult (complex) for an embryo to develop in an extreme environment? To answer this question, the research plan will decipher network topologies and subnet structuring to uncover gene connectivity patterns associated with embryo development in this polar environment. This is the new area of Environmental Genomics that the PI will explore by expanding his research experience into computational network analyses. Overall, there is a significant need for integrative biologists in the future development of environmental sciences, particularly for the application of genomic-scale technologies to answer ecological-scale questions. The educational goals of this CAREER proposal are focused at two levels in terms of interesting young students in the developing field of environmental genomics: 1) increasing the racial diversity of the scientists attracted to environmental research, and 2) increasing the awareness of career opportunities within environmental research.<br/>These educational objectives are incorporated into the research plan to engage students with the excitement of working in an extreme environment such as Antarctica and to interest them in the insights that genome-level research can reveal about how organisms are adapted to specific habitats. Working in a remote, extreme environment such as Antarctica is always a challenge. However, the adventurous nature of the work can be utilized to establish educational and outreach components of high interest to both undergraduate students and the public in general. The proposed plan will bring the experience of working in Antarctica to a larger audience through several means. These include the following: the project theme of environmental genomics will be incorporated into a new Bioinformatics curriculum currently being developed at the University of Delaware; an intern program will be implemented to involved minority undergraduate students in summer research in the United States and then to bring the students to Antarctica to participate in the research; and a K-12 education program will bring the excitement of working in Antarctica to the classrooms of thousands of children (U.S. and international) through a program produced with the Marine Science Public Education Office at the University of Delaware.