Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients
This thesis examines the role of dissolved inorganic nutrients in generating changes in phytoplankton community and pigment composition and if such changes can affect the production of the antioxidant astaxanthin in the ecosystem via pelagic copepods. The background of my studies is the possible rel...
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Uppsala universitet, Evolutionsbiologi
2004
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ftuppsalauniv:oai:DiVA.org:uu-4230 2023-05-15T15:32:56+02:00 Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients Van Nieuwerburgh, Lies 2004 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4230 eng eng Uppsala universitet, Evolutionsbiologi Uppsala : Acta Universitatis Upsaliensis Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X 968 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4230 urn:isbn:91-554-5946-3 info:eu-repo/semantics/openAccess Biology Astaxanthin Baltic Sea carotenoids diatoms eutrophication food web mesocosms microalgae M74 syndrome oxidative stress phytoplankton blooms zooplankton Biologi Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2004 ftuppsalauniv 2023-02-23T21:44:07Z This thesis examines the role of dissolved inorganic nutrients in generating changes in phytoplankton community and pigment composition and if such changes can affect the production of the antioxidant astaxanthin in the ecosystem via pelagic copepods. The background of my studies is the possible relationship between eutrophication and a reproductive disturbance in Baltic populations of Atlantic salmon (M74), which is associated with astaxanthin and thiamine deficiencies and oxidative stress. In the southern Baltic Sea, changes in nutrient loads correlate with observed trends of flagellates replacing diatoms in the phytoplankton. Copepods are the main producers of astaxanthin and a major link between phytoplankton and higher trophic levels. In laboratory and field experiments in the Baltic Sea proper and the Norwegian Sea, I show that astaxanthin synthesis in copepods is fast and depends on pigment composition of the phytoplankton diet. Among single-species diets, a diatom and a green algal cyst yielded the highest astaxanthin levels in copepods, and another diatom species, a green alga and a cyanobacterium the lowest. In nutrient-generated phytoplankton blooms in mesocosms, copepods grazing on diverse communities dominated by weakly silicified diatoms produced more astaxanthin compared with copepods grazing on communities dominated by strongly silicified diatoms. This suggests that diatoms invested in defence mechanisms and escaped grazing at surplus Si. A nutrient-starved diatom culture subjected to intraspecific competition exhibited decreased pigment levels, increased thiamine levels and increased oxidative stress. My results suggest that diatoms are beneficial for astaxanthin and thiamine production compared to other phytoplankton groups, but not under all circumstances. Copepod growth and development also responded to inorganic nutrient availability and affected total astaxanthin production per volume seawater, with highest production when the copepods grazed on diatoms. From an ecosystem perspective, ... Doctoral or Postdoctoral Thesis Atlantic salmon Norwegian Sea Copepods Uppsala University: Publications (DiVA) Norwegian Sea |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Biology Astaxanthin Baltic Sea carotenoids diatoms eutrophication food web mesocosms microalgae M74 syndrome oxidative stress phytoplankton blooms zooplankton Biologi |
spellingShingle |
Biology Astaxanthin Baltic Sea carotenoids diatoms eutrophication food web mesocosms microalgae M74 syndrome oxidative stress phytoplankton blooms zooplankton Biologi Van Nieuwerburgh, Lies Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients |
topic_facet |
Biology Astaxanthin Baltic Sea carotenoids diatoms eutrophication food web mesocosms microalgae M74 syndrome oxidative stress phytoplankton blooms zooplankton Biologi |
description |
This thesis examines the role of dissolved inorganic nutrients in generating changes in phytoplankton community and pigment composition and if such changes can affect the production of the antioxidant astaxanthin in the ecosystem via pelagic copepods. The background of my studies is the possible relationship between eutrophication and a reproductive disturbance in Baltic populations of Atlantic salmon (M74), which is associated with astaxanthin and thiamine deficiencies and oxidative stress. In the southern Baltic Sea, changes in nutrient loads correlate with observed trends of flagellates replacing diatoms in the phytoplankton. Copepods are the main producers of astaxanthin and a major link between phytoplankton and higher trophic levels. In laboratory and field experiments in the Baltic Sea proper and the Norwegian Sea, I show that astaxanthin synthesis in copepods is fast and depends on pigment composition of the phytoplankton diet. Among single-species diets, a diatom and a green algal cyst yielded the highest astaxanthin levels in copepods, and another diatom species, a green alga and a cyanobacterium the lowest. In nutrient-generated phytoplankton blooms in mesocosms, copepods grazing on diverse communities dominated by weakly silicified diatoms produced more astaxanthin compared with copepods grazing on communities dominated by strongly silicified diatoms. This suggests that diatoms invested in defence mechanisms and escaped grazing at surplus Si. A nutrient-starved diatom culture subjected to intraspecific competition exhibited decreased pigment levels, increased thiamine levels and increased oxidative stress. My results suggest that diatoms are beneficial for astaxanthin and thiamine production compared to other phytoplankton groups, but not under all circumstances. Copepod growth and development also responded to inorganic nutrient availability and affected total astaxanthin production per volume seawater, with highest production when the copepods grazed on diatoms. From an ecosystem perspective, ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Van Nieuwerburgh, Lies |
author_facet |
Van Nieuwerburgh, Lies |
author_sort |
Van Nieuwerburgh, Lies |
title |
Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients |
title_short |
Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients |
title_full |
Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients |
title_fullStr |
Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients |
title_full_unstemmed |
Experimental Studies on the Regulation of Pigment Dynamics in Phytoplankton and Copepods by Dissolved Inorganic Nutrients |
title_sort |
experimental studies on the regulation of pigment dynamics in phytoplankton and copepods by dissolved inorganic nutrients |
publisher |
Uppsala universitet, Evolutionsbiologi |
publishDate |
2004 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4230 |
geographic |
Norwegian Sea |
geographic_facet |
Norwegian Sea |
genre |
Atlantic salmon Norwegian Sea Copepods |
genre_facet |
Atlantic salmon Norwegian Sea Copepods |
op_relation |
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X 968 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4230 urn:isbn:91-554-5946-3 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766363411382272000 |