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Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores
Coccolithophores are a biogeochemically important phytoplankton group, fulfilling an important role in the global carbon cycle through primary production and the formation and export of calcium carbonate. Despite this biogeochemical importance, relatively little is known about their ecophysiology, f...
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| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2018
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| _version_ | 1867613203496697856 |
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| access_status_str | Open Access |
| author | Harington, Amy |
| author2 | Poulton, Alex |
| author_browse | Harington, Amy Poulton, Alex |
| author_facet | Poulton, Alex Harington, Amy |
| author_sort | Harington, Amy |
| collection | Thesis |
| description | Coccolithophores are a biogeochemically important phytoplankton group, fulfilling an important role in the global carbon cycle through primary production and the formation and export of calcium carbonate. Despite this biogeochemical importance, relatively little is known about their ecophysiology, for example their response to nutrient availability in terms of both macronutrient (nitrate, phosphate) and micronutrient (trace metal) or how this impacts on their competition with other phytoplankton groups (e.g. diatoms, Synechococcus). Hence, this study investigated the response of coccolithophores to trace metal (iron, zinc and cobalt) additions in the high latitude North Atlantic (Iceland and Irminger basins) and the Southern Ocean (Great Calcite Belt, Scotia Sea). The response of coccolithophores to environmental conditions was investigated by examining distribution patterns in situ and in targeted bioassays where natural communities were incubated with elevated levels of trace metal concentration. The wide range of initial conditions for these bioassays (e.g. temperature, macro- and micro-nutrient availability and phytoplankton community composition), provided valuable insights into coccolithophore responses to trace metal addition across a range of different biogeographic regions. These responses were investigated in terms of coccolithophore cell abundances, species composition, calcite production and growth rates, and were contrasted with responses of the total phytoplankton community (chlorophyll α) and abundances of diatoms and other phytoplankton groups (e.g. Synechococcus). The major finding of this thesis is that iron addition positively enhances coccolithophore growth rates and calcite production in both the Northern and Southern subpolar oceans. Another significant finding was that zinc addition also positively enhanced growth rates of coccolithophores (and diatoms) in a number of bioassays across the Great Calcite Belt (Southern Ocean). Thus, the trace metals iron and zinc are important micronutrients to consider in regulating coccolithophore growth and calcite production. As climate change potentially altering the flux of such trace metals to the ocean it is therefore important to further investigate the role of these micronutrients in regulating coccolithophore communities and their biogeochemical impact. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/27354 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:24.523Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/27354 Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores Harington, Amy Poulton, Alex Lucas, Michael I Moloney, Coleen L Marine Studies Marine Biology Coccolithophores are a biogeochemically important phytoplankton group, fulfilling an important role in the global carbon cycle through primary production and the formation and export of calcium carbonate. Despite this biogeochemical importance, relatively little is known about their ecophysiology, for example their response to nutrient availability in terms of both macronutrient (nitrate, phosphate) and micronutrient (trace metal) or how this impacts on their competition with other phytoplankton groups (e.g. diatoms, Synechococcus). Hence, this study investigated the response of coccolithophores to trace metal (iron, zinc and cobalt) additions in the high latitude North Atlantic (Iceland and Irminger basins) and the Southern Ocean (Great Calcite Belt, Scotia Sea). The response of coccolithophores to environmental conditions was investigated by examining distribution patterns in situ and in targeted bioassays where natural communities were incubated with elevated levels of trace metal concentration. The wide range of initial conditions for these bioassays (e.g. temperature, macro- and micro-nutrient availability and phytoplankton community composition), provided valuable insights into coccolithophore responses to trace metal addition across a range of different biogeographic regions. These responses were investigated in terms of coccolithophore cell abundances, species composition, calcite production and growth rates, and were contrasted with responses of the total phytoplankton community (chlorophyll α) and abundances of diatoms and other phytoplankton groups (e.g. Synechococcus). The major finding of this thesis is that iron addition positively enhances coccolithophore growth rates and calcite production in both the Northern and Southern subpolar oceans. Another significant finding was that zinc addition also positively enhanced growth rates of coccolithophores (and diatoms) in a number of bioassays across the Great Calcite Belt (Southern Ocean). Thus, the trace metals iron and zinc are important micronutrients to consider in regulating coccolithophore growth and calcite production. As climate change potentially altering the flux of such trace metals to the ocean it is therefore important to further investigate the role of these micronutrients in regulating coccolithophore communities and their biogeochemical impact. 2018-02-07T06:50:07Z 2018-02-07T06:50:07Z 2017 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/27354 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Marine Studies Marine Biology Harington, Amy Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores |
| thesis_degree_str | Doctoral |
| title | Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores |
| title_full | Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores |
| title_fullStr | Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores |
| title_full_unstemmed | Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores |
| title_short | Trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores |
| title_sort | trace metal effects on phytoplankton in subpolar seas with special emphasis on coccolithophores |
| topic | Marine Studies Marine Biology |
| url | http://hdl.handle.net/11427/27354 |
| work_keys_str_mv | AT haringtonamy tracemetaleffectsonphytoplanktoninsubpolarseaswithspecialemphasisoncoccolithophores |