Event Title

Bioavailability of Biogenic Iron Oxyhydroxides to Marine Phytoplankton

Presenter Information

Sara George, Colby CollegeFollow

Location

Parker-Reed, SSWAC

Start Date

1-5-2014 2:00 PM

End Date

1-5-2014 3:00 PM

Project Type

Poster- Restricted to Campus Access

Description

Although colloidal iron could be a meaningful iron source for phytoplankton, and iron oxidizing bacteria are present in many marine environments, the bioavailability of biogenic iron to phytoplankton remains poorly understood. Since iron is an important factor in global primary productivity and its availability has broad implications for the carbon cycle and climate, characterization of iron sources is an important step toward understanding the ocean-atmosphere biogeochemical system. Ferrozine colorimetry was used to quantify iron content of laboratory-grown and field-collected iron oxidizing bacteria (FeOB) samples. The iron oxyhydroxide stalks and sheaths were characterized by epifluorescence microscopy. In order to determine whether FeOB-produced oxyhydroxides are bioavailable to phytoplankton, Thalassiosira weissflogii and Thalassiosira pseudonana diatoms were cultured axenically with oxyhrdroxides as the sole source of iron. Growth rates and cell yields were determined with a combination of in vivo fluorometry and manual cell counts with a hemocytometer. Four different types of FeOB oxyhydroxides stimulated T. pseudonana growth. Future work could investigate mechanisms by which phytoplankton obtain iron from the solid biogenic oxyhydroxides.

Sponsoring Department

Colby College. Geology Dept.

CLAS Field of Study

Natural Sciences

Event Website

http://www.colby.edu/clas

ID

143

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May 1st, 2:00 PM May 1st, 3:00 PM

Bioavailability of Biogenic Iron Oxyhydroxides to Marine Phytoplankton

Parker-Reed, SSWAC

Although colloidal iron could be a meaningful iron source for phytoplankton, and iron oxidizing bacteria are present in many marine environments, the bioavailability of biogenic iron to phytoplankton remains poorly understood. Since iron is an important factor in global primary productivity and its availability has broad implications for the carbon cycle and climate, characterization of iron sources is an important step toward understanding the ocean-atmosphere biogeochemical system. Ferrozine colorimetry was used to quantify iron content of laboratory-grown and field-collected iron oxidizing bacteria (FeOB) samples. The iron oxyhydroxide stalks and sheaths were characterized by epifluorescence microscopy. In order to determine whether FeOB-produced oxyhydroxides are bioavailable to phytoplankton, Thalassiosira weissflogii and Thalassiosira pseudonana diatoms were cultured axenically with oxyhrdroxides as the sole source of iron. Growth rates and cell yields were determined with a combination of in vivo fluorometry and manual cell counts with a hemocytometer. Four different types of FeOB oxyhydroxides stimulated T. pseudonana growth. Future work could investigate mechanisms by which phytoplankton obtain iron from the solid biogenic oxyhydroxides.

http://digitalcommons.colby.edu/clas/2014/program/368