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Biomass, community composition and N:P recycling ratios of zooplankton in northern high-latitude lakes with contrasting levels of N deposition and dissolved organic carbon 2022 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 67, no 9, p. 1508-1520Article in journal (Refereed) Published

Abstract [en]

1. Global changes are causing decreases in inorganic nitrogen (N) concentrations, increases in coloured dissolved organic carbon (DOC) concentrations, and decreases in dissolved inorganic N to total phosphorus ratios (DIN:TP) in northern lakes. The effects of these changes on phytoplankton and zooplankton biomass and the N:P recycling ratio of zooplankton remain unresolved.
2. In 33 Swedish headwater lakes across subarctic-to-boreal gradients with different levels of N deposition (low N in the north [Västerbotten, boreal; Abisko, subarctic] vs. high N in the south [Värmland, boreal; Jämtland, subarctic]), we measured water chemistry, phytoplankton biomass (chlorophyll-a [Chl-a], Chl-a:TP), seston mineral quality (C:P, N:P), as well as zooplankton biomass, community composition, and C:N:P stoichiometry. We estimated nutrient imbalances and the N:P recycling ratios of zooplankton using ecological stoichiometry models.
3. There was a large-scale gradient from low lake DIN and DIN:TP in the north to high DIN and DIN:TP in the south, with lower DIN:TP in lakes coinciding with higher DOC within each region. Lower lake DIN was associated with lower phytoplankton biomass (lower Chl-a:TP). Lower lake DIN:TP was associated with richer seston mineral quality (lower seston C:P and N:P) and higher zooplankton biomass.
4. Zooplankton community composition differed in the north vs. south, with a dominance of N-requiring calanoid copepods with high N:P in the north and P-requiring cladocerans with low N:P in the south. Also, greater differences in zooplankton community composition were found between subarctic regions (with lower DOC) than between boreal regions (with higher DOC), suggesting that increases in lake DOC and associated declines in lake DIN:TP reduce differences in zooplankton community composition.
5. The combination of lower lake DIN, higher lake DOC, and lower lake DIN:TP led to reduced zooplankton N:P recycling ratios, possibly by reducing seston N:P and/or by enhancing calanoid copepod dominance in the zooplankton community.
6. Our findings suggest that the combination of declining N deposition and increasing lake browning in northern high-latitude lakes will reduce phytoplankton biomass, but will concurrently enhance seston mineral quality and probably also zooplankton biomass and their recycling efficiency of P relative to N.

Place, publisher, year, edition, pages

John Wiley & Sons, 2022. Vol. 67, no 9, p. 1508-1520

Keywords [en]

biomass, C:N:P stoichiometry, community composition, plankton, subarctic-to-boreal

National Category

Ecology Oceanography, Hydrology and Water Resources

Identifiers

URN: urn:nbn:se:umu:diva-197728DOI: 10.1111/fwb.13956ISI: 000814334600001Scopus ID: 2-s2.0-85132336700OAI: oai:DiVA.org:umu-197728DiVA, id: diva2:1680369

Funder

Knut and Alice Wallenberg Foundation, 2016.0083Swedish Research Council, 621‐2014‐5909Available from: 2022-07-04 Created: 2022-07-04 Last updated: 2023-03-23Bibliographically approved

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Bergström, Ann-KristinLau, Danny C. P.Jonsson, Anders

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Bergström, Ann-KristinLau, Danny C. P.Jonsson, Anders

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Department of Ecology and Environmental Sciences

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Freshwater Biology

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EcologyOceanography, Hydrology and Water Resources

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