| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
|
| Initial Amendment Date: | July 15, 2015 |
| Latest Amendment Date: | July 15, 2015 |
| Award Number: | 1524784 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Elizabeth Rom
elrom@nsf.gov (703)292-7709 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | August 1, 2015 |
| End Date: | July 31, 2017 (Estimated) |
| Total Intended Award Amount: | $99,776.00 |
| Total Awarded Amount to Date: | $99,776.00 |
| Funds Obligated to Date: |
|
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
1350 BEARDSHEAR HALL AMES IA US 50011-2103 (515)294-5225 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
253 Science I Ames IA US 50011-3212 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): |
Polar Special Initiatives, EDUCATION/HUMAN RESOURCES,OCE, ANS-Arctic Natural Sciences, EPSCoR Co-Funding |
| Primary Program Source: |
0100XXXXDB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
As summer sea ice disappears from the Arctic, we strive to know if this has happened in the past and if so, how often. Unfortunately, satellites have only been tracking sea ice since 1979. In order to determine natural fluctuations in sea ice, we need a much longer record. Sediments deposited below sea ice can extend the record of sea ice by thousands to hundreds of thousands of years. This project builds on work to develop a proxy for sea ice by looking at the relationship between diatoms (algae) found in sea ice and in the sediments below. This project will additionally attempt to increase and diversify participation in the ocean sciences by introducing a group of high-achieving, under-represented students from Iowa to the excitement of sea-ice research. The investigator and students will spend a week collecting an ice core from a frozen lake and analyzing it. The students will get to experience fieldwork and will connect research done in remote, exotic locations to the their own backyards.
Although long-term goals of the investigator are to put modern changes in the Bering Sea in the context of the geological record, the specific goals of this project are to:
1. Determine the spatial patterns of diatoms living in sea ice and sea water across the Bering Sea Shelf in spring 2006 and 2007.
2. Determine the seasonal succession of diatoms living in sea ice and open water over the Chukchi Sea Shelf from summer 2015 to summer 2016.
The investigator will examine diatom assemblages in a collection of seawater, sea ice, and sediment trap samples and then compare these assemblages to those in the top 1 cm of sediments below. Seawater and sea ice samples were collected in 2006 and 2007, while the sediment trap samples will come from the Chukchi Ecosystem Mooring which will begin collecting a full annual cycle of diatom sedimentation this summer. The investigator will count cleaned diatoms at 1000x magnification using standard counting methods and taxonomy, identifying to the species level whenever possible.
The driving hypothesis of the research is that a predictable subset of diatoms is in the ice algal and spring blooms and is also in the sediments directly below. The investigator also aims to test the long-held hypothesis that sea ice diatoms are preferentially dissolved at the sea surface.
A robust sea ice proxy is essential for realistically reconstructing past sea ice extent and retreat in the Arctic Ocean. This work will serve to ground statistically based sea ice proxy in ecological reality. This pilot study, awarded to a new researcher at Iowa State who is in the process of establishing her lab, will be leveraged to launch a larger, sea-based study that will include deploying sediment traps in the Bering Sea. Research results will enable climate modelers to use records of sea ice during previous warmings to predict how primary productivity and sea ice will change in the coming decades and to anticipate the ecosystem-scale impacts such changes may precipitate.
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.
As sea ice continues to decline in the Arctic, it is important to be able to put this decline in a long-term context. Satellite observations of sea ice extend only a few decades, which means in order to know how much sea ice was present in the past, we need to develop an indirect method, or proxy, for measuring sea ice. This award allowed us to finalize such a proxy for the Bering and Chukchi seas and also allowed us to ground our sea ice proxy in ecological reality. We used single-celled algae, called diatoms, that make their cell walls out of silica glass and so are preserved in marine sediments for millions of years. Different species of diatoms have different ecological preferences and so by looking at a grid of sites (Fig. 1), identifying which species are preserved on the sea floor today at these sites and comparing those species to spring sea ice coverage, we built a quantitative, diatom-based, sea ice proxy. This proxy uses 5 species of diatom (Fig. 1) in a statistical model, the Generalized Additive Model, to predict sea ice coverage. When we take this model and apply it back in time to when the Earth transitioned from a glacial period to an interglacial period, the reconstruction appears to be robust.
In addition to this proxy, we described a new diatom genus and species that is associated with extensive sea ice, Sinerima marigela (Fig. 1b). We identified all diatom species in our sediment network and related them to a variety of environmental variables like sea surface temperature and nutrient concentration. This analysis lets us define more qualitative proxies based on these diatoms, so we can say things like, when species a is replaced by species b, the water temperature warmed. Finally, we have begun analyzing a sediment trap that collected sediments settling through the water column over the course of a full year. Periodically a different jar would open on this sediment trap so that we have 24 samples, each of them containing about 2 weeks of sediments. This analysis will let us understand the yearly progression of diatom species and show us which ones in particular grow when sea ice is present. This final analysis teaches us the ecology of our qualitative and quantitative proxies.
This project allowed an undergraduate and three graduate students to contribute to the research. In particular, it is the backbone of one woman’s PhD dissertation and it has contributed to the undergraduate’s decision to pursue graduate school to further study ancient climate change. We used our research in presentations to middle and high school students to show them how we evaluate whether current climate change is unprecedented. In addition, we took part in a series of workshops at the Ames Public Library where residents could ask questions about climate change. We purchased a Mark V ice corer. It will be used in the Bering Sea in future projects, but this equipment is currently being used to develop outreach trips for potential geology majors at Iowa State University, to illustrate the breadth of geosciences, and in an undergraduate senior thesis looking at the organisms that live in lake ice.
Last Modified: 10/30/2017
Modified by: Beth E Caissie
Please report errors in award information by writing to: awardsearch@nsf.gov.
