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Trace metals and the ecology of marine cyanobacteria

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dc.contributor.advisor Sallie W. Chisholm. en_US Mann, Elizabeth Lowell, 1966- en_US
dc.contributor.other Joint Program in Oceanography. en_US 2005-08-22T20:46:30Z 2005-08-22T20:46:30Z 2000 en_US 2000 en_US
dc.description Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Biology; and Woods Hole Oceanographic Institution), 2000. en_US
dc.description Includes bibliographical references. en_US
dc.description.abstract The marine cyanobacteria Synechococcus and Prochlorococcus are important primary producers in oligotrophic oceans. The abundance and cell division rates of these cyanobacteria can be influenced by trace metals such as iron and copper. Iron is an essential trace metal that is present in the high nutrient, low chlorophyll waters of the equatorial Pacific in extremely low concentrations. When these waters were enriched with iron, Prochlorococcus chlorophyll fluorescence per cell and cell size increased. Cell division rates doubled inside the iron enriched patch and reached two divisions per day in bottle incubations with additional iron, indicating that Prochlorococcus were iron limited. However, cell numbers remained constant because mortality rates nearly doubled after the addition of iron and essentially matched the increases in cell division rate. Trace metals can also be present in toxic, rather than limiting concentrations. Copper is an essential trace element that is toxic to cyanobacteria in pM quantities. In stratified water columns in the Sargasso Sea, free Cu2+ concentrations are high in the mixed layer (up to 6pM) and most of the Prochlorococcus population is located below the thermocline where free Cu2+ concentrations are lower. The distribution of Synechococcus is more uniform with depth. Prochlorococcus isolates were more sensitive to copper than Synechococcus, but members of the low chi BIA (high light adapted) ecotype were less sensitive than strains with high chi BIA ratios (low light adapted). In the field, the in situ concentration of free Cu2+ had a strong effect on the copper sensitivity of Prochlorococcus. Net growth rates were substantially reduced when Prochlorococcus from environments where the in situ free Cu2+ was low (deep mixed layers and below the thermocline in stratified water) were exposed to copper. Prochlorococcus in shallow mixed layers where in situ Cu2 + was high were less sensitive to copper and may have been members of the copper resistant low chi B/ A ecotype. Synechococcus were relatively copper resistant across a range of environments. These data are consistent with the hypothesis that ambient copper levels may influence the relative abundance of Prochlorococcus and Synechococcus in the Sargasso Sea. en_US
dc.description.statementofresponsibility by Elizabeth Lowell Mann. en_US
dc.format.extent 176 leaves en_US
dc.format.extent 11191007 bytes
dc.format.extent 11190765 bytes
dc.format.mimetype application/pdf
dc.format.mimetype application/pdf
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.subject Biology. en_US
dc.subject Joint Program in Oceanography. en_US
dc.subject Woods Hole Oceanographic Institution. en_US
dc.title Trace metals and the ecology of marine cyanobacteria en_US
dc.type Thesis en_US Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Biology. en_US
dc.contributor.department Joint Program in Oceanography. en_US
dc.contributor.department Woods Hole Oceanographic Institution. en_US
dc.identifier.oclc 44948499 en_US

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