USAP-DC

{"dp_type": "Dataset", "free_text": "Population Dynamics"}

[{"awards": "1840058 Jenouvrier, Stephanie; 1246407 Jenouvrier, Stephanie", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Mon, 27 Jun 2022 00:00:00 GMT", "description": "Individuals differ in many ways. Most produce few offspring; a handful produce many. Some\r\ndie early; others live to old age. It is tempting to attribute these differences in outcomes to differences in individual traits, and thus in the demographic rates experienced. However, there is\r\nmore to individual variation than meets the eye of the biologist. Even among individuals sharing identical traits, life history outcomes (life expectancy and lifetime reproduction) will vary due\r\nto individual stochasticity, i.e., to chance. Quantifying the contributions of heterogeneity and\r\nchance is essential to understanding natural variability. Inter-individual differences vary across environmental conditions, hence heterogeneity and stochasticity depend on environmental conditions. We show that favorable conditions increase the contributions of individual stochasticity, and reduce the contributions of heterogeneity, to variance in demographic outcomes in a seabird population. The opposite is true under poor conditions. This result has important consequence for understanding the ecology and evolution of life history strategies.\r\n\r\nSpecifically, three life-history complexes exist in a population of southern fulmar (defined as sets of life-history characteristics that occur together through the lifetime of an individual). They are reminiscent of the gradient of life- history strategy observed among species:\r\n\r\n1. Group 1 (14% of offspring at fledging) is a slow-paced life history where individuals tend to delay recruitment, recruit successfully, and extend their reproductive lifespan.\r\n2. Group 2 (67% of offspring at fledging) consists of individuals that are less likely to recruit, have high adult survival, and skip breeding often.\r\n3. Group 3 (19% of offspring at fledging) is a fast-paced life history where individuals recruit early and attempt to breed often but have a short lifespan.\r\n\r\nIndividuals in groups 1 and 3 are considered \u201chigh-quality\u201d individuals because they produce, on average, more offspring over their lives than do individuals in group 2. But group 2 is made-up of individuals that experience the highest levels of adult survival.\r\n \r\nDifferences between these groups, i.e. individual heterogeneity, only explains a small fraction of variance in life expectancy (5.9%) and lifetime reproduction (22%) when environmental conditions are ordinary. We expect that the environmental context experienced, especially when environmental conditions get extreme, is key to characterizing individual heterogeneity and its contribution to life history outcomes. Here, we build on previous studies to quantify the impact of extreme environmental conditions on the relative contributions of individual heterogeneity and stochasticity to variance in life history outcomes.\r\nWe found that the differences in vital rates and demographic outcomes among complexes depend on the sea ice conditions individuals experience. Importantly, differences across life history complexes are amplified when sea ice concentration get extremely low. Sea ice conditions did not only affect patterns of life history traits, but also the variance of life history outcomes and the relative proportion of individual unobserved heterogeneity to the total variance. These new results advance the current debate on the relative importance heterogeneity (i.e. potentially adaptive) and stochasticity (i.e. enhances genetic drift) in shaping potentially neutral vs. adaptive changes in life histories.\r\n", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Biology; Biosphere; Birds; Cryosphere; East Antarctica; Southern Fulmar", "locations": "East Antarctica; Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Jenouvrier, Stephanie", "project_titles": "Linking Foraging Behaviors to Demography to understand Albatrosses Population Responses to Climate Change; Polar Seabirds with Long-term Pair Bonds: Effects of Mating on Individual Fitness and Population Dynamics", "projects": [{"proj_uid": "p0010002", "repository": "USAP-DC", "title": "Linking Foraging Behaviors to Demography to understand Albatrosses Population Responses to Climate Change"}, {"proj_uid": "p0010090", "repository": "USAP-DC", "title": "Polar Seabirds with Long-term Pair Bonds: Effects of Mating on Individual Fitness and Population Dynamics"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Demographic outputs and their variances for three life history complexes for the Southern Fulmar across contrasted sea ice conditions.", "uid": "601585", "west": -180.0}, {"awards": "1840058 Jenouvrier, Stephanie", "bounds_geometry": null, "date_created": "Fri, 04 Feb 2022 00:00:00 GMT", "description": "Many animals form long-term monogamous pair-bonds, and the disruption of a pair-bond (through either divorce or widowhood) can have significant consequences for individual vital rates (survival, breeding, and breeding success probabilities) and life-history outcomes (lifetime reproductive success, life expectancy). Here, we investigated the causes and consequences of pair-bond disruption in wandering albatross (Diomedea exulans). State-of-the-art statistical and mathematical approaches were developed to estimate divorce and widowhood rates and their impacts on vital rates and life-history outcomes. In this population, females incur a higher mortality rate due to incidental fishery bycatch, hence the population is male-skewed. Therefore, we first posited that males show higher widowhood rates negatively correlated with fishing effort, and females have higher divorce rates because they have more mating opportunities. Furthermore, we expected that divorce can be an adaptive strategy, whereby individuals improve breeding success by breeding with a new partner of better quality. Finally, we posited that pair-bond disruptions can reduce survival and breeding probabilities due to the cost of remating processes, with important consequences for life-history outcomes. As expected, we show that males have higher widowhood rates than females and females have higher divorce rates in this male-skewed population. However, no correlation was found between fishing effort and male widowhood. Secondly, contrary to our expectation, we found that divorce is likely non-adaptive in this population. We propose that divorce in this population is caused by an intruder who outcompetes the original partner in line with the \"forced divorce\" hypothesis. Furthermore, we found a 16.7% and 18.0% reduction in lifetime reproductive success (LRS) only for divorced and widowed males, respectively, due to missing breeding seasons after a pair-bond disruption. Finally, we found that divorced individuals are more likely to divorce again, but whether this is related to specific individual characteristics remains an important area of investigation. \r\n\r\nDescription of data processing:\r\nThis file includes: (1) observation events data; (2) E-surge GEPAT (Generator of pattern of elementary matrices) code for fitting MULTIEVENT-CAPTURE-MARK-RECAPTURE (MECMR) models; and (3) pair-bond status and breeding success data to perform all the analysis described in Sun et al. (2022, Ecological Monographs) ", "east": null, "geometry": null, "keywords": "Antarctica; Biology; Cryosphere; Wandering Albatross", "locations": "Antarctica", "north": null, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Jenouvrier, Stephanie; Sun, Ruijiao; Barbraud, Christophe; Delord, Karine", "project_titles": "Polar Seabirds with Long-term Pair Bonds: Effects of Mating on Individual Fitness and Population Dynamics", "projects": [{"proj_uid": "p0010090", "repository": "USAP-DC", "title": "Polar Seabirds with Long-term Pair Bonds: Effects of Mating on Individual Fitness and Population Dynamics"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": null, "title": "Causes and consequences of pair-bond disruption in a sex-skewed population of a long-lived monogamous seabird: the wandering Albatross", "uid": "601518", "west": null}, {"awards": "1443424 McMahon, Kelton; 1443386 Emslie, Steven; 1443585 Polito, Michael; 1826712 McMahon, Kelton", "bounds_geometry": ["POLYGON((-37.33 -54.05,-37.192 -54.05,-37.054 -54.05,-36.916 -54.05,-36.778 -54.05,-36.64 -54.05,-36.502 -54.05,-36.364 -54.05,-36.226 -54.05,-36.088 -54.05,-35.95 -54.05,-35.95 -54.107,-35.95 -54.164,-35.95 -54.221,-35.95 -54.278,-35.95 -54.335,-35.95 -54.392,-35.95 -54.449,-35.95 -54.506,-35.95 -54.563,-35.95 -54.62,-36.088 -54.62,-36.226 -54.62,-36.364 -54.62,-36.502 -54.62,-36.64 -54.62,-36.778 -54.62,-36.916 -54.62,-37.054 -54.62,-37.192 -54.62,-37.33 -54.62,-37.33 -54.563,-37.33 -54.506,-37.33 -54.449,-37.33 -54.392,-37.33 -54.335,-37.33 -54.278,-37.33 -54.221,-37.33 -54.164,-37.33 -54.107,-37.33 -54.05))"], "date_created": "Thu, 13 Jan 2022 00:00:00 GMT", "description": "This data set contains radiometric dating measurements from two aquatic sediment cores excavated from two separate sites (Salisbury Plain and Gold Harbor) on South Georgia Island in February 2019. It also contains biological and geochemical sediment proxy values from both sediment cores, including total carbon (%), total nitrogen (%), number of penguin feathers and eggshell fragments, number of seal hairs, and \u03b413C and \u03b415N stable isotope values. Cores were sectioned at 1cm intervals, and radiometric dating analyses were conducted on sediment fractions \u003c850 \u00b5m by measuring for 210Pb and 226Ra (via 214Pb) by direct gamma counting using the high purity germanium planar detector in the Marine Geochemistry Laboratory at Louisiana State University (LSU). The 210Pbex profiles were used to calculate sedimentation rates using a steady state model that assumes constant rate of supply and constant sedimentation rate (Maiti et al., 2010). Geochemical analyses were performed on sediment fractions \u003c125 \u00b5m using an Elemental Analyzer-Isotope Ratio Mass Spectrometry (EA-IRMS) in the Stable Isotope Ecology Lab at LSU. Biological counts of feathers and hairs were determined by enumeration using a dissecting microscope of sediment fractions \u003e1000 \u00b5m. The data set also includes sediment core excavation site names and coordinates, date of excavation, sediment depth and age, and carbon to nitrogen isotopic ratios. Details of the data set and all relevant methods are provided in Kristan et al., 2021.", "east": -35.95, "geometry": ["POINT(-36.64 -54.335)"], "keywords": "Antarctica; Antarctic Fur Seal; Cryosphere; Elemental Concentrations; King Penguin; Population Dynamics; South Atlantic Ocean; South Georgia Island; Stable Isotope Analysis; Sub-Antarctic", "locations": "South Atlantic Ocean; South Georgia Island; Sub-Antarctic; Antarctica", "north": -54.05, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Kristan, Allyson; Maiti, Kanchan; McMahon, Kelton; Polito, Michael", "project_titles": "Collaborative Research: Investigating Holocene Shifts in the Diets and Paleohistory of Antarctic Krill Predators", "projects": [{"proj_uid": "p0010047", "repository": "USAP-DC", "title": "Collaborative Research: Investigating Holocene Shifts in the Diets and Paleohistory of Antarctic Krill Predators"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -54.62, "title": "Radiometric dating, geochemical proxies, and predator biological remains obtained from aquatic sediment cores on South Georgia Island.", "uid": "601509", "west": -37.33}, {"awards": "1744794 Jenouvrier, Stephanie; 2037561 Jenouvrier, Stephanie", "bounds_geometry": ["POLYGON((-180 -60,-144 -60,-108 -60,-72 -60,-36 -60,0 -60,36 -60,72 -60,108 -60,144 -60,180 -60,180 -63,180 -66,180 -69,180 -72,180 -75,180 -78,180 -81,180 -84,180 -87,180 -90,144 -90,108 -90,72 -90,36 -90,0 -90,-36 -90,-72 -90,-108 -90,-144 -90,-180 -90,-180 -87,-180 -84,-180 -81,-180 -78,-180 -75,-180 -72,-180 -69,-180 -66,-180 -63,-180 -60))"], "date_created": "Wed, 08 Dec 2021 00:00:00 GMT", "description": "Climate impacts are not always easily discerned in wild populations as detecting climate change signals in populations is challenged by stochastic noise associated with natural climate variability, variability in biotic and abiotic processes, and observation error in demographic rates. Detection of the impact of climate change on populations requires making a formal distinction between signals in the population associated with long-term climate trends from those generated by stochastic noise. The time of emergence (ToE) identifies when the signal of anthropogenic climate change can be quantitatively distinguished from natural climate variability. This concept has been applied extensively in the climate sciences, but has not been explored in the context of population dynamics. \r\n\r\nIn Jenouvrier et al. (Global Change Biology, accepted), we outline an approach to detecting climate-driven signals in populations based on an assessment of when climate change drives population dynamics beyond the envelope characteristic of stochastic variations in an unperturbed state. \r\n\r\nThis data set is the code of a theoretical assessment of the time of emergence of climate-driven signals in population dynamics. We identify the dependence of time of emergence in populations on the magnitude of both trends and variability in climate and also explore the effect of intrinsic demographic controls on the time of emergence in population. We demonstrate that different life histories (fast species vs. slow species), demographic processes (survival, reproduction) and the relationships between climate and demographic rates, yield population dynamics that filter climate trends and variability differently. \r\n\r\nIn Jenouvrier et al. (accepted), we also illustrate empirically how to detect the point in time when anthropogenic signals in populations emerge from stochastic noise for a species threatened by climate change: the emperor penguin. This data set also includes a detailed Table and code to analyze those results.\r\n", "east": 180.0, "geometry": ["POINT(0 -89.999)"], "keywords": "Antarctica; Cryosphere", "locations": "Antarctica; Antarctica", "north": -60.0, "nsf_funding_programs": "Antarctic Organisms and Ecosystems; Antarctic Ocean and Atmospheric Sciences", "persons": "Jenouvrier, Stephanie; jenouvrier, stephanie", "project_titles": "A Multi-scale Approach to Understanding Spatial and Population Variability in Emperor Penguins; Integrating Antarctic Environmental and Biological Predictability to Obtain Optimal Forecasts", "projects": [{"proj_uid": "p0010229", "repository": "USAP-DC", "title": "A Multi-scale Approach to Understanding Spatial and Population Variability in Emperor Penguins"}, {"proj_uid": "p0010282", "repository": "USAP-DC", "title": "Integrating Antarctic Environmental and Biological Predictability to Obtain Optimal Forecasts"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -90.0, "title": "Detecting climate signals in populations: case of emperor penguin", "uid": "601491", "west": -180.0}, {"awards": "1246407 Jenouvrier, Stephanie", "bounds_geometry": ["POLYGON((68.5 -48.5,68.725 -48.5,68.95 -48.5,69.175 -48.5,69.4 -48.5,69.625 -48.5,69.85 -48.5,70.075 -48.5,70.3 -48.5,70.525 -48.5,70.75 -48.5,70.75 -48.65,70.75 -48.8,70.75 -48.95,70.75 -49.1,70.75 -49.25,70.75 -49.4,70.75 -49.55,70.75 -49.7,70.75 -49.85,70.75 -50,70.525 -50,70.3 -50,70.075 -50,69.85 -50,69.625 -50,69.4 -50,69.175 -50,68.95 -50,68.725 -50,68.5 -50,68.5 -49.85,68.5 -49.7,68.5 -49.55,68.5 -49.4,68.5 -49.25,68.5 -49.1,68.5 -48.95,68.5 -48.8,68.5 -48.65,68.5 -48.5))"], "date_created": "Mon, 03 Dec 2018 00:00:00 GMT", "description": "1. Studies of the mechanisms underlying climate-induced population changes are critically needed to better understand and accurately predict population responses to climate change. Long-lived migratory species might be particularly vulnerable to climate change as they are constrained by different climate conditions and energetic requirements during the breeding and non-breeding seasons. Yet, most studies primarily focus on the breeding season of these species life cycle. Environmental conditions experienced in the non-breeding season may have downstream effects on the other stages of the annual life cycle. Not investigating such effects may potentially lead to erroneous inferences about population dynamics.\r\n2. Combining demographic and tracking data collected between 2006 and 2013 at Kerguelen Island on a long-lived migratory seabird, the Black-Browed Albatross (Thalassarche melanophris), we investigated the links between sea surface temperature during the non-breeding season and behavioural and phenological traits (at-sea behaviour and migratory schedules) while accounting for different responses between birds of different sex and reproductive status (previously failed or successful breeders). We then explored whether variation in the foraging behaviour and timing of spring migration influenced subsequent reproductive performance.\r\n3. Our results showed that foraging activity and migratory schedules varied by both sex and reproductive status suggesting different energetic requirements and constraints among individuals. Higher sea surface temperatures during late winter, assumed to reflect poor winter conditions, were associated with an earlier departure from the wintering grounds and an extended pre-breeding period. However, an earlier spring migration and an earlier return to Kerguelen grounds were associated with a lower breeding success.\r\n4. Our results highlighted that behaviour during some periods of the non-breeding season, particularly towards the end of the wintering period and the pre-breeding period, had a significant effect on the subsequent reproductive success. Therefore caution needs to be given to all stages of the annual cycle when predicting the influence of climate on population dynamics.", "east": 70.75, "geometry": ["POINT(69.625 -49.25)"], "keywords": "Albatross; Animal Behavior Observation; Antarctica; Biology; Biosphere; Birds; Black-Browed Albatross (Thalassarche Melanophris); Field Investigations; foraging; Kerguelen Island; Ocean Island/Plateau; Southern Ocean", "locations": "Kerguelen Island; Antarctica; Southern Ocean", "north": -48.5, "nsf_funding_programs": "Antarctic Organisms and Ecosystems", "persons": "Jenouvrier, Stephanie", "project_titles": "Linking Foraging Behaviors to Demography to understand Albatrosses Population Responses to Climate Change", "projects": [{"proj_uid": "p0010002", "repository": "USAP-DC", "title": "Linking Foraging Behaviors to Demography to understand Albatrosses Population Responses to Climate Change"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -50.0, "title": "Linking oceanographic conditions, migratory schedules and foraging behaviour during the non-breeding season to reproductive performance in a long-lived seabird", "uid": "601140", "west": 68.5}, {"awards": "0439906 Koch, Paul", "bounds_geometry": ["POLYGON((162 -72,162.6 -72,163.2 -72,163.8 -72,164.4 -72,165 -72,165.6 -72,166.2 -72,166.8 -72,167.4 -72,168 -72,168 -72.6,168 -73.2,168 -73.8,168 -74.4,168 -75,168 -75.6,168 -76.2,168 -76.8,168 -77.4,168 -78,167.4 -78,166.8 -78,166.2 -78,165.6 -78,165 -78,164.4 -78,163.8 -78,163.2 -78,162.6 -78,162 -78,162 -77.4,162 -76.8,162 -76.2,162 -75.6,162 -75,162 -74.4,162 -73.8,162 -73.2,162 -72.6,162 -72))"], "date_created": "Fri, 01 Jan 2010 00:00:00 GMT", "description": "During previous NSF-sponsored research, the PI\u0027s discovered that southern elephant seal colonies once existed along the Victoria Land coast (VLC) of Antarctica, a region where they are no longer observed. Molted seal skin and hair occur along 300 km of coastline, more than 1000 km from any extant colony. The last record of a seal at a former colony site is at ~A.D. 1600. Because abandonment occurred prior to subantarctic sealing, disappearance of the VLC colony probably was due to environmental factors, possibly cooling and encroachment of land-fast, perennial sea ice that made access to haul-out sites difficult. The record of seal inhabitation along the VLC, therefore, has potential as a proxy for climate change. Elephant seals are a predominantly subantarctic species with circumpolar distribution. Genetic studies have revealed significant differentiation among populations, particularly with regard to that at Macquarie I., which is the extant population nearest to the abandoned VLC colony. Not only is the Macquarie population unique genetically, but it is has undergone unexplained decline of 2%/yr over the last 50 years3. In a pilot study, genetic analyses showed a close relationship between the VLC seals and those at Macquarie I. An understanding of the relationship between the two populations, as well as of the environmental pressures that led to the demise of the VLC colonies, will provide a better understanding of present-day population genetic structure, the effect of environmental change on seal populations, and possibly the reasons underlying the modern decline at Macquarie Island. This project addresses several key research problems: (1) Why did elephant seals colonize and then abandon the VLC? (2) What does the elephant seal record reveal about Holocene climate change and sea-ice conditions? (3) What were the foraging strategies of the seals and did these strategies change over time as climate varied? (4) How does the genetic structure of the VLC seals relate to extant populations? (5) How did genetic diversity change over time and with colony decline? (6) Using ancient samples to estimate mtDNA mutation rates, what can be learned about VLC population dynamics over time? (7) What was the ecological relationship between elephant seals and Adelie penguins that occupied the same sites, but apparently at different times? The proposed work includes the professional training of young researchers and incorporation of data into graduate and undergraduate courses.\n\nBecause of extreme isolation of the Antarctic continent since the \nEarly Oligocene, one expects a unique invertebrate benthic fauna with \na high degree of endemism. Yet some invertebrate taxa that constitute \nimportant ecological components of sedimentary benthic communities \ninclude more than 40 percent non-endemic species (e.g., benthic \npolychaetes). To account for non-endemic species, intermittent genetic \nexchange must occur between Antarctic and other (e.g. South American) \npopulations. The most likely mechanism for such gene flow, at least \nfor in-faunal and mobile macrobenthos, is dispersal of planktonic \nlarvae across the sub- Antarctic and Antarctic polar fronts. To test \nfor larval dispersal as a mechanism of maintaining genetic continuity \nacross polar fronts, the scientists propose to (1) take plankton \nsamples along transects across Drake passage during both the austral \nsummer and winter seasons while concurrently collecting the \nappropriate hydrographic data. Such data will help elucidate the \nhydrographic mechanisms that allow dispersal across Drake Passage. \nUsing a molecular phylogenetic approach, they will (2) compare \nseemingly identical adult forms from Antarctic and South America \ncontinents to identify genetic breaks, historical gene flow, and \ncontrol for the presence of cryptic species. (3) Similar molecular \ntools will be used to relate planktonic larvae to their adult forms. \nThrough this procedure, they propose to link the larval forms \nrespectively to their Antarctic or South America origins. The proposed \nwork builds on previous research that provides the basis for this \neffort to develop a synthetic understanding of historical gene flow \nand present day dispersal mechanism in South American/Drake Passage/ \nAntarctic Peninsular region. Furthermore, this work represents one of \nthe first attempts to examine recent gene flow in Antarctic benthic \ninvertebrates. Graduate students and a postdoctoral fellow will be \ntrained during this research\n", "east": 168.0, "geometry": ["POINT(165 -75)"], "keywords": "Biology; Biosphere; Isotope; Penguin; Ross Sea; Seals; Southern Ocean", "locations": "Ross Sea; Southern Ocean", "north": -72.0, "nsf_funding_programs": null, "persons": "Koch, Paul", "project_titles": "Collaborative Research: Abandoned Elephant Seal Colonies in Antarctica: Integration of Genetic, Isotopic, and Geologic Approaches toward Understanding Holocene Environmental Change", "projects": [{"proj_uid": "p0000533", "repository": "USAP-DC", "title": "Collaborative Research: Abandoned Elephant Seal Colonies in Antarctica: Integration of Genetic, Isotopic, and Geologic Approaches toward Understanding Holocene Environmental Change"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -78.0, "title": "Abandoned Elephant Seal Colonies in Antarctica: Integration of Genetic, Isotopic, and Geologic Approaches toward Understanding Holocene Environmental Change", "uid": "600041", "west": 162.0}, {"awards": "0440478 Tang, Kam", "bounds_geometry": ["POINT(166.66267 -77.85067)"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "Phaeocystis Antarctica is a widely distributed phytoplankton that forms dense blooms and aggregates in the Southern Ocean. This phytoplankton and plays important roles in polar ecology and biogeochemistry, in part because it is a dominant primary producer, a main component of organic matter vertical fluxes, and the principal producer of volatile organic sulfur in the region. Yet P. Antarctica is also one of the lesser known species in terms of its physiology, life history and trophic relationships with other organisms; furthermore, information collected on other Phaeocystis species and from different locations may not be applicable to P. Antarctica in the Ross Sea. P. Antarctica occurs mainly as two morphotypes: solitary cells and mucilaginous colonies, which differ significantly in size, architecture and chemical composition. Relative dominance between solitary cells and colonies determines not only the size spectrum of the population, but also its carbon dynamics, nutrient uptake and utilization. Conventional thinking of the planktonic trophic processes is also challenged by the fact that colony formation could effectively alter the predator-prey interactions and interspecific competition. However, the factors that regulate the differences between solitary and colonial forms of P. Antarctica are not well-understood. \n\nThe research objective of this proposal is therefore to address these over-arching questions: \n1. Do P. Antarctica solitary cells and colonies differ in growth, composition and photosynthetic rates? 2. How do nutrients and grazers affect colony development and size distribution of P. Antarctica? \n3. How do nutrients and grazers act synergistically to affect the long-term population dynamics of P. Antarctica? \n\nExperiments will be conducted in the McMurdo station with natural P. Antarctica assemblages and co-occurring grazers. Laboratory experiments will be conducted to study size-specific growth and photosynthetic rates of P. Antarctica, size-specific grazing mortality due to microzooplankton and mesozooplankton, the effects of macronutrients on the (nitrogen compounds) relative dominance of solitary cells and colonies, and the effects of micronutrient (Fe) and grazing related chemical signals on P. Antarctica colony development. Because this species is of critical importance in the Southern Ocean, and because this research will provide critical information on factors that regulate the role of P.Antarctica in food webs and biogeochemical cycles, a major gap in knowledge will be addressed. This project will train two marine science Ph.D. students. The investigators will also collaborate with the School of Education and a marine science museum to communicate polar science to a broader audience.", "east": 166.66267, "geometry": ["POINT(166.66267 -77.85067)"], "keywords": "Biology; Biosphere; McMurdo Sound; Oceans; Phytoplankton; Ross Sea; Southern Ocean; Zooplankton", "locations": "McMurdo Sound; Ross Sea; Southern Ocean", "north": -77.85067, "nsf_funding_programs": null, "persons": "Smith, Walker; Tang, Kam", "project_titles": "Environmental and Ecological Regulation of Differences and Interactions between Solitary and Colonial forms of Phaeocystis antarctica", "projects": [{"proj_uid": "p0000214", "repository": "USAP-DC", "title": "Environmental and Ecological Regulation of Differences and Interactions between Solitary and Colonial forms of Phaeocystis antarctica"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -77.85067, "title": "Environmental and Ecological Regulation of Differences and Interactions between Solitary and Colonial Forms of Phaeocystis Antarctica", "uid": "600043", "west": 166.66267}, {"awards": "0634682 Kanatous, Shane", "bounds_geometry": ["POLYGON((160 -77,160.7 -77,161.4 -77,162.1 -77,162.8 -77,163.5 -77,164.2 -77,164.9 -77,165.6 -77,166.3 -77,167 -77,167 -77.1,167 -77.2,167 -77.3,167 -77.4,167 -77.5,167 -77.6,167 -77.7,167 -77.8,167 -77.9,167 -78,166.3 -78,165.6 -78,164.9 -78,164.2 -78,163.5 -78,162.8 -78,162.1 -78,161.4 -78,160.7 -78,160 -78,160 -77.9,160 -77.8,160 -77.7,160 -77.6,160 -77.5,160 -77.4,160 -77.3,160 -77.2,160 -77.1,160 -77))"], "date_created": "Thu, 01 Jan 2009 00:00:00 GMT", "description": "During the past three decades, intensive field studies have revealed much about the behavior, physiology, life history, and population dynamics of the Weddell seal (Leptonychotes weddelli) population of McMurdo Sound, Antarctica. These animals are marine predators that are highly adapted for an aquatic life in shore-fast and pack ice habitats. They must locate and capture sparsely distributed under the ice. Most of what is known about their diving behavior is based on studies of adult animals with little known about the development or the genetic controls of diving behavior of young animals. The goal of this project is to examine the temporal development of aerobic capacity, lipid metabolism and oxygen stores in the skeletal muscles of young Weddell seals and to determine which aspects of the cellular environment are important in the regulation of these adaptations during maturation. This project builds on past results to investigate the molecular controls that underlie the development of these adaptations. The first objective is to further characterize the ontogenetic changes in muscle aerobic capacity, lipid metabolism and myoglobin concentration and distribution using enzymatic, immuno-histochemical and myoglobin assays in newly weaned, subadult, and adult seals. The second objective is to determine the molecular controls that regulate these changes in aerobic capacity, fiber type distribution and myoglobin in skeletal muscles during maturation. Through subtractive hybridization and subsequent analysis, differences in mRNA populations in the swimming muscles of the different age classes of Weddell seals will be determined. These techniques will allow for the identification of the proteins and transcription factors that influence the ontogenetic changes in myoglobin concentration, fiber type distribution and aerobic capacity. These results will increase our understanding of both the ontogeny and molecular mechanisms by which young seals acquire the physiological capabilities to make deep (up to 700 m) and long aerobic dives (ca 20 min). This study will advance knowledge of the molecular regulation for the adaptations that enable active skeletal muscle to function under hypoxic conditions; this has a broader application for human medicine especially in regards to cardiac and pulmonary disease. Additional broader impacts include the participation of underrepresented scientists and a continuation of a website in collaboration with the Science Teachers Access to Resources at Southwestern University (STARS Program) which involves weekly updates about research efforts during the field season, weekly questions/answer session involving students and teachers, and updates on research results throughout the year.", "east": 167.0, "geometry": ["POINT(163.5 -77.5)"], "keywords": "Antarctica; Biology; Biosphere; Oceans; Seals; Sea Surface; Southern Ocean", "locations": "Sea Surface; Antarctica; Southern Ocean", "north": -77.0, "nsf_funding_programs": null, "persons": "Lyons, W. Berry; Kanatous, Shane", "project_titles": "The Molecular Signals that Regulate the Ontogeny of Aerobic Capacity, Lipid Metabolism and Elevated Myoglobin Concentrations in the Skeletal Muscles of Weddell Seals", "projects": [{"proj_uid": "p0000536", "repository": "USAP-DC", "title": "The Molecular Signals that Regulate the Ontogeny of Aerobic Capacity, Lipid Metabolism and Elevated Myoglobin Concentrations in the Skeletal Muscles of Weddell Seals"}], "repo": "USAP-DC", "repositories": "USAP-DC", "science_programs": null, "south": -78.0, "title": "The Molecular Signals that Regulate the Ontogeny of Aerobic Capacity, Lipid Metabolism and Elevated Myoglobin Concentrations in the Skeletal Muscles of Weddell Seals", "uid": "600063", "west": 160.0}]

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