Antarctic foraminifera and their implications on paleoclimate

Holocene foraminiferal assemblages from Firth of Tay, Antarctic Peninsula: Paleoclimate implications

By: Wojciech Majewski & John B. Anderson

Summarized by: Baron Hoffmeister

What data were used?: This study analyzed 166 sediment samples taken from sediment cores in the Antarctic Peninsula. 

Methods: This study used a quantitative analysis of foraminifera assemblages found in sediment cores to determine past environmental factors relating to climate change.  

Results: This study found that different foraminifera and their physical attributes correlate with several different environmental conditions during the Holocene epoch, the geologic time unit that spans from nearly 11,000 years ago to present time ( figure 1). A time span between 9400 years and 7750 years before present time was correlated with having coarse (large) sediment and coarse foraminifera. This indicates a high influence from warming sea currents that melted glaciers and deposited coarse sediments. This was a period of glacial retreat and warming temperatures. From 7750 to 6000 years before the present, the elevated appearance of foraminifera species M. arenacea represents open water and conditions in which glaciers were spread out from each other. The foraminifera species M. arenacea is also known for its tolerance to cold corrosive bottom waters and high salinity fluctuations. The assemblage dominated by M. arenacea indicates that the bottom waters at this time dissolved other species of foraminifera, and M. arenacea was the dominant foraminifera species at this time. Foraminifera tests, (i.e., their shells) are made of calcium carbonate, and it dissolves in acidic conditions. Around 3500 years before the present time, it was found that due to an increase in abundance of foraminifera species P. bartramiP. antarctica is when the cooling trend of the mid-Holocene occurred. There weren’t any corresponding foraminifera assemblages found that correlate with warming over the last century. 

Image contains many examples of foraminifera at different angles to showcase the variation and how it can be employed as a tool to assess climate.
Different species of foraminifera can be used to identify different ecological conditions in which they existed. The physical properties of foraminifera, like roundness or angularity of their tests, can also determine transport history, depositional environments, and likely effects from environmental influences. This is a microscopic image of several different foraminifera species found in the core samples used for this study. The different shapes of this foraminifera and the textures observed were used to determine environmental conditions in the Antarctic peninsula.

Why is this study important?: The results of this study allow us to better understand how foraminifera can relate to changing environmental conditions. This study provides a more cohesive understanding of climate change and how glacier and ocean currents around the south pole respond to changes in climate. The data used in this study can be used in future studies regarding foraminifera assemblages and their implication on climate change. 

The big picture: Foraminifera are some of the most abundant shelled organisms in marine environments and can be used to reconstruct past climatic conditions. The importance of understanding how these organisms correlate to climate change can help link current-day climate trends to prehistoric climate events. This can be used to make predictions on how climate change is occurring currently, and what the effects of it might be worldwide. 

Citation: Majewski, W., & Anderson, J. B. (2009). Holocene foraminiferal assemblages from Firth of Tay, Antarctic Peninsula: Paleoclimate implications. Marine Micropaleontology, 73(3-4), 135-147. doi:10.1016/j.marmicro.2009.08.003

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.