2003 Marley B. Bice Outstanding Marine Science Project Falmouth High School Science Fair   Email     Print   PDF

National Ocean Science Bowl (NOSB)
6th Annual Blue Lobster Bowl
March 7-8, 2003
Falmouth High School Science Fair, Falmouth, MA

CICOR Outstanding Project in the Marine Sciences Recipient Marley B. Bice

Project Summary: Do the Oxygen Isotopes of Foraminifera Record Temperature?

The objective of this project was to examine how well the temperatures inferred from the oxygen isotope ratios (d¹⁸O) in the skeletons of different species of planktonic foraminifera record the temperature of the water in which the forams grew. Scientists studying future climate change use d¹⁸O in forams from sea floor sediments to understand past climate change. But the isotopic temperature record and month of bloom of different planktonic species is not well understood.

The study area is in the North Atlantic Ocean, near 40°N, 70°W. The samples were collected in 1981-82 and were stored in buffered solutions. I sieved the solutions and extractedcarbonate skeletons of several different species of planktonic foraminifera. d¹⁸O was measured on a mass spectrometer at Woods Hole Oceanographic Institution. Based on salinity, I estimated the d¹⁸O value of the water for this area and calculated temperatures using a published equilibrium equation. I compared the resulting temperatures to oceanographic measurements made by others in this area of the Atlantic. The results show that the species Globigerina ruber pink and G. sacculifer are generally good recorders of sea surface temperature. On the other hand, G. inflata records winter surface temperature but then tends to live in deeper, colder water during the summer months. I found that some samples had been poorly buffered while in storage so that the low pH in these samples dissolved forams. This meant that I was not able to reconstruct a full year’s temperature cycle. The data I did get show that the foram d¹⁸O records temperature and that G. ruber pink and G. sacculifer would be the best to use in reconstructing past sea surface temperatures.