| NSF Org: |
OPP Office of Polar Programs (OPP) |
| Recipient: |
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| Initial Amendment Date: | July 3, 2012 |
| Latest Amendment Date: | July 3, 2012 |
| Award Number: | 1204033 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Gregory Anderson
greander@nsf.gov (703)292-4693 OPP Office of Polar Programs (OPP) GEO Directorate for Geosciences |
| Start Date: | February 1, 2013 |
| End Date: | January 31, 2018 (Estimated) |
| Total Intended Award Amount: | $487,728.00 |
| Total Awarded Amount to Date: | $487,728.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
201 OLD MAIN UNIVERSITY PARK PA US 16802-1503 (814)865-1372 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
207 Deike Building University Park PA US 16802-5000 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | ARCSS-Arctic System Science |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.078 |
ABSTRACT
This project will provide new data on the paleoclimates, paleoenviroments and the biodiversity impacts of sea level rise on the southern edge of the Bering Land Bridge (BLB), and is intended to facilitate a better understanding of why woolly mammoths survived late into the mid-Holocene only in the environments of Arctic islands of this area. Furthermore, this research will attempt to establish the actual time of extinction of the Holocene mammoth population on St. Paul Island, Pribilof Islands, Alaska, and apply this information to test various proposed causal hypotheses for the extinction.
Cores from Cagaloq Lake, St. Paul, will be sampled for chironomids (aquatic invertebrates), pollen, coprophilous fungi spores, plant macrofossils, charcoal, ancient DNA and cryptotephras. Oxygen isotopes from the heads of chironomids will provide an independent climate record that can be supplemented by paleoecological analyses of the chironomid assemblages. Studies will also test chironomid species for isotope fractionation to disentangle climate signals from ground water effects. Terrestrial community changes will be reconstructed from pollen, spores and plant macrofossils; and charcoal frequency will be used to document fire events. Analysis of ancient DNA will provide data on cryptic plant and animal species that have not been detected by traditional methods of analysis, and can also be used to identify taxa to species.
Spores that grow on animal dung will be used as proxies for the mammoth population size and to document the time of mammoth extinction on the island. Ancient DNA will serve as an important cross-check by helping to resolve specific identifications of these spores as well as providing an independent estimate the time of extinction by the absence of mammoth DNA.
Digital elevations, bathymetric data, sea level curves, and Geographic Information System (GIS) technology will be used to reconstruct island size from the time of its isolation until today. A highly constrained chronology of the Cagaloq record will be achieved by using 14 C dates and tephras. All data can be compared temporally in order to test hypotheses for mammoth extinction.
This project will provide opportunities for two PhD students, a postdoctoral fellow, graduate student assistant and undergraduate student. Results of the study will be disseminated widely in peer-reviewed journals. An exhibit on the results of the project will be prepared by the EMS Museum at Penn State University with a web component. In addition, a special on-line, interactive exhibit will allow participants to reconstruct the island at various sizes, populate it with differing mammoth populations and define different climate and environmental factors to observe how each of these components affects mammoth extinction. The interactive exhibit will be available on the Neotoma database. Members of the group will make presentations on the project at the Alaska Quaternary Center in Fairbanks, which serves as a hub for promoting Alaska Quaternary research and outreach to the public.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Last Mammoths of North America
Radiocarbon dates on woolly mammoth (Mammuthus primigenius) remains from Quaganax cave on St. Paul Island established their Holocene survival (ca. 6.840 years ago). Unfortunately, it was uncertain if these dates documented the final extinction and there was not any direct evidence for the potential causes of extinction. The purpose of this project was to collect sediment cores from Lake Hill Lake, about 0.5 km from Quaganax Cave. Unlike the cave fossils, lake cores provided a continuous sedimentary record from about 20 ka years ago until today and revealed a host of paleoenvironmental proxies.
After cores were taken from Lake Hill, an interdisciplinary team developed a composite stratigraphy, collected sediment samples at close intervals (1-10 cm), and analyzed them for information documenting the time and the cause(s) of extinction. Next, an age model was established for analyzing the proxies from the core. Timing of extinction was determined by dating the disappearance of mammoth ancient DNA (aDNA) and spores from three (Sporormiella, Sordaria, and Podospora) coprophilous fungi that lived on the dung of large mammals (i.e., mammoths). Mammoth sedaDNA is present in all tested sediment samples between 10,850 ±150 y ago (the oldest sample tested) and 5,650 ± 80 y ago and absent in samples younger than 5,610 ±80 y ago. Sporormiella and Sordaria spores terminate at 5,680 ± 80 y ago and 5,650 ± 80 y ago, respectively, the latter exactly coinciding with the last appearance of mammoth sedaDNA. Overall, the close agreement among these independent proxies makes 5,600 ± 100 y ago one of the most robust and precise estimates of timing ever recorded for a prehistoric species extinction.
Humans could not be implicated in this extinction event because archaeological survey of the island indicated it was uninhabited until the 1780s when it was discovered by Russian whalers. Likewise, polar bear predation was eliminated by radiocarbon dates on polar bear remains from the cave that showed they also did not occupy the island until thousands of years after the extinction of the mammoths. There was not any evidence in the sediments at the time of extinction for volcanic eruptions. Habitat destruction and increasing winter snowpack, proposed hypotheses of extinction, were eliminated by pollen and isotope data, respectively. The extinction was indirectly, but not directly, related to a reduction in island size because size was stabilized more than 4000 years before the extinction. Island size probably did reduce mammoth populations and limit the availability of fresh water resources by inundating coastal lakes. Reduction in the availability of fresh water, as indicated by diatoms (fresh water microscopic plants), cladocera (water fleas) and isotopic data, was probably the primary driver of extinction.
Like modern elephants, mammoths probably required copious amounts of water daily (at least 200 gallons per individual). In fact, because of the woolly mammoth’s adaptations (hair length, hair structure, fat deposits, small ears, etc.) to retard heat loss, it may have even required more water daily in the warm Holocene. A shift towards more arid climates around 9 ka would have initiated fresh water depletion (evaporation from lakes) but this was enhanced by the erosional activities of mammoths around the few existing water holes. Furthermore, a shift from more shrub-dominated vegetation to one of more herbs occurred after the extinction, so it could not be a cause but probably was an outcome of the mammoth extinction. Likewise, the shift in lake sedimentation was also a consequence of mammoth extinction.
This study reinforces the concept of the vulnerability of island populations for extinction and suggests that the extinction process can be complicated and direct causes may not be readily apparent at first.
Last Modified: 07/26/2018
Modified by: Russell W Graham
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