Dr. Beth E Caissie

Assistant Professor
Beth Caissie

I am a marine sedimentologist who uses diatoms to understand the history of sea ice in the Bering Sea. I am focused on developing a diatom-based sea ice proxy that uses not only statistical relationships between sediment diatom assemblages, morphology, and modern sea ice extent, but also takes into account known ecological preferences of certain diatoms. This work can be used to put current Arctic climate change into the context of the geologic record and help society to better prepare for future sea ice decline in the Arctic.

Research: 

We are developing a method for estimating sea ice concentration in the past. This project is characterizing diatom assemblages and morphology in a database of surface sediments from the Bering and Chukchi seas and relating them statistically to satellite-derived sea ice duration for each site. We are using both traditional transfer functions and data mining techniques to understand these relationships. Additionally, in collaboration with UMass Amherst, we are measuring a molecular biomarker (IP25) in these sediments and exploring its utility as a proxy for ice concentration. IP25 is produced by Haslea sp. and other diatoms when living in sea ice.

Area of Expertise: 
Paleoceanography
Broader Impact: 

Sea ice is a defining feature of our planet. It serves as habitat for some of the most spectacular animals on Earth—polar bears, walrus, and ice seals—as well as for some of the smallest primary producers: sea ice diatoms. Declining sea ice has the potential to further increase global temperatures through the ice-albedo feedback. Dark open waters will absorb incoming radiation in contrast to the white surface of sea ice, which reflects solar radiation. Because of this, it is critical to understand how sea ice will decline as temperatures rise. One way to do this is to look at how sea ice changed in the past when the earth warmed due to natural forcings.

Key Environmental Science Publications: 

Nesterovich, A. and Caissie. B.E., 2018. Taxonomy and ultrastructure of Sinerima, a new genus of diatoms (Bacillariophyta), with a description of a new species, S. marigelaPhytotaxa, 351 (3), 197-209, doi:10.11646/phytotaxa.351.3.1.

Pelto, B.M., Caissie, B.E., Petsch, S.T. and Brigham-Grette, J., 2018. Oceanographic and Climatic Change in the Bering Sea, Last Glacial Maximum to Holocene. Paleoceanography and Paleoclimatologydoi:10.1002/2017PA003265.

Vaughn, D.R. and Caissie, B.E., 2017. Effects of sea-level, sea-ice extent and nutrient availability on primary production at the Umnak Plateau, Bering Sea (IODP Site U1339) during Marine Isotope Stage (MIS) 5. Palaeogeography, Palaeoclimatology, Palaeoecologydoi:10.1016/j.palaeo.2017.06.020.

Caissie, B. E., Brigham-Grette, J., Cook, M. S., and Colmenero-Hidalgo, E. 2016. Bering Sea surface water conditions during Marine Isotope Stages 12 to 10 at Navarin Canyon (IODP Site U1345). Climate of the Pastdoi:10/5194/cp-12-1739-2016.

Weckström, K., Miettinen, A., Caissie, B.E., Pearce, C., Ellegaard, M., Krawczyk, D., and Witkowski, A., 2014. Sea surface temperatures in Disko Bay during the Little Ice Age – Caution needs to be exercised before assigning Thalassiosira kushirensis resting spore as a warm-water indicator in palaeoceanographic studies. Comment on: Late-Holocene diatom derived seasonal variability in hydrological conditions off Disko Bay, West Greenland by Diana W. Krawczyk, Andrzej Witkowski, Jeremy Lloyd, Matthias Moros, Jan Harff and Antoon Kuijpers.Quaternary Science Reviewsdoi:10.1016/j.quascirev.2014.07.015.

Takahashi, K.A., Ravelo, C., Alvarez Zarikian, C. and Expedition 323 Scientists, 2011. IODP Expedition 323–Pliocene and Pleistocene Paleoceanographic Changes in the Bering Sea. Scientific Drilling vol. 11, pp 4‐13, doi:10.2204/iodp.sd.11.01.2011.

Caissie, B.E., Brigham-Grette, J., Lawrence, K.T., Herbert, T.D. and Cook, M.S., 2010. Last Glacial Maximum to Holocene Sea Surface Conditions at Umnak Plateau, Bering Sea as Inferred from Diatom, Alkenone, and Stable Isotope Records. Paleoceanographydoi:10.1029/2008PA001671.

Contact
153 Science Hall
Ames
Iowa
50011