A1 Journal article (refereed)
Increasing air temperature relative to water temperature makes the mixed layer shallower, reducing phytoplankton biomass in a stratified lake (2023)


Ahonen, S. A., Seppälä, J., Karjalainen, J. S., Kuha, J., & Vähätalo, A. V. (2023). Increasing air temperature relative to water temperature makes the mixed layer shallower, reducing phytoplankton biomass in a stratified lake. Freshwater Biology, 68(4), 577-587. https://doi.org/10.1111/fwb.14048


JYU authors or editors


Publication details

All authors or editorsAhonen, Salla A.; Seppälä, Jukka; Karjalainen, Juha S.; Kuha, Jonna; Vähätalo, Anssi V.

Journal or seriesFreshwater Biology

ISSN0046-5070

eISSN1365-2427

Publication year2023

Publication date13/01/2023

Volume68

Issue number4

Pages range577-587

PublisherWiley-Blackwell

Publication countryUnited Kingdom

Publication languageEnglish

DOIhttps://doi.org/10.1111/fwb.14048

Publication open accessOpenly available

Publication channel open accessPartially open access channel

Publication is parallel published (JYX)https://jyx.jyu.fi/handle/123456789/85183


Abstract

The depth of the mixed layer is a major determinant of nutrient and light availability for phytoplankton in stratified waterbodies. Ongoing climate change influences surface waters through meteorological forcing, which modifies the physical structure of fresh waters including the mixed layer, but effects on phytoplankton biomass are poorly known.
To determine the responses of phytoplankton biomass to the depth of the mixed layer, light availability and associated meteorological forcing, we followed daily changes in weather and water column properties in a boreal lake over the first half of a summer stratification period.
Phytoplankton biomass increased with the deepening of the mixed layer associated with high wind speeds and low air temperature relative to the temperature of the mixed layer (Tair−Tmix < 0), whereas heatwave conditions—shallow mixed layer driven by high Tair−Tmix value and low wind speed—reduced the biomass.
Improving light availability from low to moderate light conditions increased the phytoplankton biomass, while the highest light availability was associated with low phytoplankton biomass.
Our study demonstrates that the climatic impact-drivers wind speed and Tair−Tmix are major drivers of mixed layer depth, which controlled phytoplankton biomass during the early summer stratification period. Our study suggests that increasing air temperature relative to water temperature and declining wind speeds have potential to lead to reduced phytoplankton biomass due to a shallower mixed layer during the first half of the stratification period in non-eutrophic lakes with sufficient light availability.


Keywordsbiomass (ecology)climate changeswater systemslakeswater quality

Free keywordsalgal biomass; climate warming; heatwave; lake mixing; thermal stratification


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Related projects


Ministry reportingYes

VIRTA submission year2023

JUFO rating2


Last updated on 2024-12-10 at 16:00