Change search
ReferencesLink to record
Permanent link

Direct link
Amino acid stable isotope discrimination in diverse aquatic food chains
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
2015 (English)Manuscript (preprint) (Other academic)Text
Place, publisher, year, edition, pages
2015.
National Category
Ecology
Research subject
Marine Ecology
Identifiers
URN: urn:nbn:se:su:diva-124337OAI: oai:DiVA.org:su-124337DiVA: diva2:885111
Available from: 2015-12-18 Created: 2015-12-18 Last updated: 2015-12-18Bibliographically approved
In thesis
1. Species interactions and energy transfer in aquatic food webs
Open this publication in new window or tab >>Species interactions and energy transfer in aquatic food webs
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Food webs are structured by intricate nodes of species interactions which govern the flow of organic matter in natural systems. Despite being long recognized as a key component in ecology, estimation of food web functioning is still challenging due to the difficulty in accurately measuring species interactions within a food web. Novel tracing methods that estimate species diet uptake and trophic position are therefore needed for assessing food web dynamics.

The focus of this thesis is the use of compound specific nitrogen and carbon stable isotopes and molecular techniques for assessing predator-prey interactions and energy flow in natural aquatic ecosystems, with a particular focus on the species links between phytoplankton and zooplankton.

The use of δ15N amino acid values to predict organism trophic position are evaluated through a meta-analysis of available literature which included measurements from 359 marine species (article I). Through a controlled feeding study isotope incorporation in aquatic organisms, across both plant-animal and animal-animal species linkages is further assessed (article II).

These studies showed that δ15N amino acid values are useful tools for categorizing animal trophic position. Organism feeding ecology influenced nitrogen trophic discrimination (difference in isotope ratio between consumer and diet), with higher discrimination in herbivores compared to omnivores and carnivores (article I). Nitrogen isotope trophic discrimination also varied among feeding treatments in the laboratory study (article II). The combined findings from articles I & II suggest that researchers should consider using group specific nitrogen trophic discrimination values to improve accuracy in species trophic position predictions. 

Another key finding in the controlled laboratory study (article II) was consistently low carbon isotope discrimination in essential amino acids across all species linkages, confirming that these compounds are reliable dietary tracers.

The δ13C ratios of essential amino acids were applied to study seasonal dynamics in zooplankton resource use in the Baltic Sea (article III). Data from this study indicated that zooplankton assimilate variable resources throughout the growing season. Molecular diet analysis (article IV) showed that marine copepod and cladoceran species ingested both autotrophic and heterotrophic resources.

Evidence from both articles III & IV also revealed that zooplankton feed on a relatively broad range of diet items but not opportunistically on all available food sources. Mesozooplankton feeding patterns suggested that energy and nutritional flows were channelled through an omnivorous zooplankton food web including microzooplankton prey items. Overall the results of this thesis highlight that stable isotope ratios in specific compounds and molecular techniques are useful tracing approaches that improve our understanding of food web functioning.

Place, publisher, year, edition, pages
Stockholm: Department of Ecology, Environment and Plant Sciences, Stockholm University, 2015. 40 p.
Keyword
Aquatic food webs, zooplankton, stable isotope analysis amino acids, molecular diet analysis
National Category
Ecology
Research subject
Marine Ecology
Identifiers
urn:nbn:se:su:diva-123600 (URN)978-91-7649-316-8 (ISBN)
Public defence
2016-01-26, Vivi Täckholmsalen (Q-salen), NPQ-huset, Svante Arrhenius väg 20, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 4: Manuscript.

 

Available from: 2015-12-30 Created: 2015-11-30 Last updated: 2016-01-04Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Nielsen, Jens M.Winder, MonikaHansson, Sture
By organisation
Department of Ecology, Environment and Plant Sciences
Ecology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 481 hits
ReferencesLink to record
Permanent link

Direct link