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Phytoplankton biomass controls tocopherol concentrations in Baltic Sea zooplankton
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Ecological Botany.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
Department of Systems Ecology, Stockholm University.
(English)In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599Article in journal (Refereed) Submitted
Abstract [en]

Nearly all organisms are constantly exposed to oxidative threat, because every reaction where oxygen is involved gives rise to oxidants. Efficient protection is provided by antioxidants. Vitamin E (tocopherol) is an essential plant-derived antioxidant and poorly studied so far in marine food webs. In 2004 and 2005 eight offshore expeditions were conducted in the Baltic Sea to explore the dynamics of α-tocopherol in the pelagic food web. In order to analyze tocopherol production and transition to the next food web level, two plankton size classes were sampled; <100 µm (dominated by phytoplankton) and >200 µm (dominated by calanoid copepods). HPLC analysis revealed lowest values of α-tocopherol per L seawater in March in both size classes and highest in May for <100 µm (31.5 ng L-1) and August for >200 µm (1.3 ng L-1). No consistent seasonal pattern could be observed in α-tocopherol per unit biomass for the zooplankton. Concentrations ranged in <100 µm from 0.05 to 0.10 ng µg C-1 and in >200 µm from 0.05 to 0.11 ng µg C-1.  Partial least square regression (PLS) revealed nutrional status and species composition of the phytoplankton biomass as driving factors of α-tocopherol production in phytoplankton. Abiotic factors, as depth and temperature were only of significant influence in May. In zooplankton, the α-tocopherol concentration was negatively associated with phytoplankton biomass in May. Therefore we concluded that assimilation efficiency of zooplankton in combination with high phytoplankton biomass is the bottle-neck in tocopherol transport from phytoplankton to higher levels in the food web.

Keyword [en]
Vitamin E; Food web; Phytoplankton; Zooplankton; Baltic Sea
URN: urn:nbn:se:uu:diva-130140OAI: oai:DiVA.org:uu-130140DiVA: diva2:346643
Available from: 2010-09-02 Created: 2010-09-02 Last updated: 2011-01-10Bibliographically approved
In thesis
1. Dynamics of astaxanthin, tocopherol (Vitamin E) and thiamine (Vitamin B1) in the Baltic Sea ecosystem: Bottom-up effects in an aquatic food web
Open this publication in new window or tab >>Dynamics of astaxanthin, tocopherol (Vitamin E) and thiamine (Vitamin B1) in the Baltic Sea ecosystem: Bottom-up effects in an aquatic food web
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis combines laboratory experiments and field expeditions to study production, transfer and consumption of non-enzymatic antioxidants and thiamine in an aquatic food web. In particular, I (1) documented spatial and seasonal variation of tocopherols and carotenoids in the Baltic Sea pelagic food web, and (2) examined the effects of abiotic and biotic factors on tocopherol, carotenoid and thiamine concentrations in phytoplankton, zooplankton and fish.

Moderate differences in temperature and salinity affected α-tocopherol, β-carotene and thiamine production in microalgae. Furthermore, the results suggest that acute stress favors the expression of non-enzymatic antioxidants rather than enzymatic antioxidants. Because production of α-tocopherol, β-carotene and thiamine differ markedly between microalgae, the availability of non-enzymatic antioxidants and thiamine is likely to be highly variable in the Baltic Sea and is difficult to predict.

The transfer of non-enzymatic antioxidants from phytoplankton to zooplankton was biomass dependent. The field expeditions revealed that phytoplankton biomass was negatively associated with α-tocopherol concentration in mesozooplankton. Thus, increased eutrophication of the Baltic Sea followed by an increase in phytoplankton biomass could decrease the transfer of essential biochemicals to higher levels in the pelagic food web. This could lead to deficiency syndromes, of the kind already observed in the Baltic Sea. Astaxanthin is synthesized from precursors provided by the phytoplankton community. Thus biomass dependent transfer of astaxanthin precursors from phytoplankton to zooplankton could be responsible for astaxanthin deficiency in zooplanktivorous herring. Astaxanthin in herring consists mostly of all-Z-isomers, which are characterized by low bioavailability. Therefore, astaxanthin deficiency in salmon could be explained by the low concentration of this substance and its isomeric composition in herring.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 47 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 762
Baltic Sea, carotenoids, astaxanthin, tocopherols, Vitamin E, thiamine, Vitamin B1, pelagic food web, eutrophication, M74, phytoplankton, zooplankton, sprat, Sprattus sprattus balticus, herring, Clupea harengus, salmon, Salmo salar, cod, Gadus morhua, High Performance Liquid Chromatography (HPLC), electrochemical detection (ECD)
urn:nbn:se:uu:diva-130143 (URN)978-91-554-7878-0 (ISBN)
Public defence
2010-10-15, Lindahlsalen, Norbyvägen 18, EBC, Uppsala, 10:00 (English)
Available from: 2010-09-23 Created: 2010-09-02 Last updated: 2011-01-10

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