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Julie Richey, Caitlin Reynolds, and colleagues retrieved a sediment trap from the northern Gulf of Mexico during a 3-day cruise (February 7–9, 2020) on board the R/V Pelican. The trap was deployed in 1,200 m of water in 2008 and had been collecting sinking particles from the water column to be used in paleoclimate proxy-calibration studies. 

Photo of planktic foraminifers from the Gulf of Mexico sediment trap seen through the microscope
Photograph of planktic foraminifers collected from the sediment trap. Magnified 255x. (Credit: Jessica Spear. Public domain.)

The cruise was also an educational opportunity for undergraduate students from Eckerd College and University of South Carolina who assisted with data collection on board a research vessel for the first time.

Scientists have only been able to directly measure changes in Earth’s climate since the 1970’s. To understand changes in climate prior to this time period, proxy-based reconstructions must be made by using the signatures preserved in geologic archives such as trees, ice cores, corals, and marine sediments. These proxies provide information on climate and oceanic variability, including changes in temperature and salinity over time. However, the value of these proxies is dependent on calibration between the chemistry of the proxy and environmental conditions.

Planktic foraminifera are microscopic organisms that live in open water and act as a proxy by incorporating chemical properties of their environment into their calcium carbonate shells before sinking and being buried on the seafloor. The information stored in their shells can later be extracted by scientists to understand climate characteristics at the time the foraminifer was living (up to millions of years in the past). Modern measurements of the shell chemistry from foraminifera skeletons collected in the sediment trap, combined with measured environmental parameters, will allow scientists to fine-tune estimates of past climate change.

 

Read what else is new at the St. Petersburg Coastal and Marine Science Center.

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