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The influence of food quality (P:C ratios) on RNA:DNA ratios and somatic growth rate of Daphnia
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution.
2002 In: Limnology and Oceanography, Vol. 47, 487-494 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2002. Vol. 47, 487-494 p.
URN: urn:nbn:se:uu:diva-95732OAI: oai:DiVA.org:uu-95732DiVA: diva2:170057
Available from: 2007-04-11 Created: 2007-04-11Bibliographically approved
In thesis
1. Food Quality Effects on Zooplankton Growth and Energy Transfer in Pelagic Freshwater Food Webs
Open this publication in new window or tab >>Food Quality Effects on Zooplankton Growth and Energy Transfer in Pelagic Freshwater Food Webs
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Effekter av födokvalitet på djurplanktons tillväxt och på energiöverföringen i födovävar i sjöar
Abstract [en]

Poor food quality can have large negative effects on zooplankton growth and this can also affect food web interactions. The main aims of this thesis were to study the importance of different food quality aspects in Daphnia, to identify potentially important differences among zooplankton taxa, and to put food quality research into a natural context by identifying the importance of food quality and quantity in lakes of different nutrient content.

In the first experiment, the RNA:DNA ratio was positively related to the somatic growth rate of Daphnia, supporting a connection between P content, RNA content, and growth rate. The second experiment showed that EPA was important for Daphnia somatic growth, and 0.9 µg EPA mg C-1 was identified as the threshold below which negative effects on Daphnia growth occurred.

A field survey identified patterns in the PUFA content of zooplankton that could be explained by taxonomy and trophic position. Cladocera enriched EPA and ARA relative to seston, and Copepoda primarily enriched DHA. In a whole-lake experiment, gentle fertilization of an oligotrophicated reservoir increased the seston P content and the biomass of high quality phytoplankton (Cryptophyceae, high EPA content). This was followed by increases in zooplankton and fish biomasses.

An empirical model based on data from a literature survey predicted that food quantity is most important for zooplankton growth in oligotrophic lakes, and that food quality factors are more important in eutrophic lakes. Thus, zooplankton growth, and energy transfer efficiency in the food web, is predicted to be highest in mesotrophic lakes. The results predict that the strength and nature of food quantity and quality limitation of Daphnia growth varies with lake trophic state, and that some combination of food quantity and/or quality limitation should be expected in nearly all lakes.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 43 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 292
Ecology, elemental stoichiometry, phosphorus, polyunsaturated fatty acids, EPA, oligotrophic lakes, empirical modelling, Daphnia, Cladocera, Copepoda, Ekologi
National Category
urn:nbn:se:uu:diva-7811 (URN)978-91-554-6859-0 (ISBN)
Public defence
2007-05-04, Zootissalen, Gamla Zoologen, Norbyvägen 18, Uppsala, 10:00
Available from: 2007-04-11 Created: 2007-04-11 Last updated: 2016-04-28Bibliographically approved

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