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A carbon budget for an oligotrophic clearwater lake in mid-Sweden
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
2006 (English)In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 68, no 1, 52-64 p.Article in journal (Refereed) Published
Abstract [en]

In this study, a whole-lake carbon budget for the oligotrophic, clearwater Lake Eckarfjärden was established both on an annual and seasonal basis. For budget calculations, the lake was divided into three habitats (pelagial, littoral and benthic) and the biota into 19 functional groups. In the lake, major parts of biomass (97%) and primary production (91%) are concentrated in benthic and littoral habitats and to a few functional groups. Respiration on the other hand, is focused on benthic and pelagial habitats where 60% and 39%, respectively, of the respiration took place. Our conceptual model indicates strong interactions between habitats. For instance, the pelagial is fed with carbon fixed by primary producers in the benthic and littoral zones. On an annual basis, total primary production exceeds total respiration and the lake is net autotrophic. However, there are clear differences between habitats and between seasons. For instance, the littoral is net autotrophic during spring, summer and autumn, the benthic habitat is net autotrophic only during summer, and the pelagial is always net heterotrophic. Our results demonstrate clear couplings between habitats and organisms and the importance of a holistic view when studying lake ecosystems.

Place, publisher, year, edition, pages
2006. Vol. 68, no 1, 52-64 p.
Keyword [en]
Lake Eckarfjärden, functional groups, carbon flows, habitat interactions, metabolic processes
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-93058DOI: 10.1007/s00027-005-0807-0OAI: oai:DiVA.org:uu-93058DiVA: diva2:166418
Available from: 2005-05-11 Created: 2005-05-11 Last updated: 2013-09-20Bibliographically approved
In thesis
1. Benthic-Pelagic Microbial Interactions and Carbon Cycling in Clearwater Lakes
Open this publication in new window or tab >>Benthic-Pelagic Microbial Interactions and Carbon Cycling in Clearwater Lakes
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on the interactions among microbiota in clearwater lakes. Field sampling and field experiments were performed to evaluate interactions among microbiota and the importance of benthic versus pelagic microbiota in terms of biomass and production. In addition, carbon cycling in an oligotrophic clearwater lake was calculated.

Biomass and production of microbiota was clearly focused to the benthic habitat. During natural nutrient concentrations growth of heterotrophic bacteria (benthic and pelagic) was coupled to production of microphytobenthos in Lake Eckarfjärden, indicating interactions between autotrophic and heterotrophic microbiota in, as well as between, habitats. At increased nutrient concentrations, growth of heterotrophic bacteria was not correlated to microphytobenthos production. This was explained by less release of dissolved organic carbon (DOC) from microphytobenthos when they got access to more nutrients. Further investigations showed different scenarios in oligotrophic clearwater lakes following increased nutrient concentrations. The interactions between microbiota may be altered following increased nutrient concentrations and the microbial mat either positively or negatively affect the pelagic microbiota. The most striking result was that the expected shift towards dominance of pelagic primary production does not necessarily occur.

Major flows of carbon were identified between different habitats in the oligotrophic clearwater Lake Eckarfjärden, and the net result was that the benthic habitat provided carbon to the pelagial. High DOC concentrations in the lake together with low pelagic production are factors that would indicate net heterotrophy. Accordingly, the pelagial of Lake Eckarfjärden was net heterotrophic but when the benthic and littoral habitats were included in the calculations, the lake turned out to be net autotrophic.

In conclusion, the benthic microbiota contributed significantly to the total production in the investigated lakes and had a major role in the lake metabolism. Thus, this thesis emphasises the importance of benthic microbiota in shallow clearwater lakes.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. 39 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 52
Biology, microphytobenthos, phytoplankton, heterotrophic bacteria, interactions, nutrients, carbon cycling, clearwater lakes, Biologi
National Category
Biological Sciences
urn:nbn:se:uu:diva-5798 (URN)91-554-6251-0 (ISBN)
Public defence
2006-02-03, Ekmanssalen, Kärnhuset, EBC, Norbyvägen 14, Uppsala, 10:00 (English)
Available from: 2005-05-11 Created: 2005-05-11 Last updated: 2009-03-31Bibliographically approved

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