Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i>
Cyanobacteria dominance and warming have been suggested to decrease the production of polyunsaturated fatty acids (PUFA) in freshwater ecosystems. Physiological adaptations of poikilothermic animals to higher temperatures may further decrease PUFA levels in aquatic food webs. We conducted diet manip...
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doaj-2a18cb8628334ab6b2541532fc3ccdcc2021-09-25T23:47:33ZengMDPI AGBiomolecules2218-273X2021-09-01111326132610.3390/biom11091326Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i>Ursula Strandberg0Timo Ilo1Jarkko Akkanen2Paula Kankaala3Department of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, FinlandDepartment of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, FinlandDepartment of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, FinlandDepartment of Environmental and Biological Sciences, University of Eastern Finland, 80101 Joensuu, FinlandCyanobacteria dominance and warming have been suggested to decrease the production of polyunsaturated fatty acids (PUFA) in freshwater ecosystems. Physiological adaptations of poikilothermic animals to higher temperatures may further decrease PUFA levels in aquatic food webs. We conducted diet manipulation experiments to investigate the combined effects of dietary PUFA and warming on the proportions of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) in <i>Chironomus riparius</i>. The experimental diet consisted of a nontoxic cyanobacterium <i>Microcystis</i>, which contained C<sub>20</sub> PUFA: 20:3n-3, 20:4n-3, and 20:3n-6, but no EPA or ARA. Additionally, we used TetraMin<sup>®</sup> fish flakes as a control treatment. A temperature increase from 20 °C to 25 °C decreased the proportion of n-3 C<sub>20</sub> PUFA and the n-3/n-6 ratio in <i>Microcystis</i>. Diet manipulation experiments indicated that <i>Chironomus</i> desaturated dietary C<sub>20</sub> precursors to EPA and ARA, but warming decreased this bioconversion and resulted in lower levels of EPA and ARA in <i>Chironomus</i>. Warming did not alter the proportions of EPA and ARA in <i>Chironomus</i> larvae if these PUFA were readily available in the diet (TetraMin<sup>®</sup> control treatment). In conclusion, warming and cyanobacteria dominance may decrease the production and trophic transfer of physiologically important PUFA in freshwaters by (1) decreasing the n-3/n-6 ratio and the abundance of n-3 C<sub>20</sub> precursors in <i>Microcystis</i>, and (2) decreasing the bioconversion of n-3 and n-6 C<sub>20</sub> precursors to EPA and ARA in chironomids. These changes may have cascading effects throughout the food web and decrease the content of EPA in fish, potentially affecting its availability to humans.https://www.mdpi.com/2218-273X/11/9/1326ARAclimate change<i>Chironomus riparius</i>desaturationEPA |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Ursula Strandberg Timo Ilo Jarkko Akkanen Paula Kankaala |
spellingShingle |
Ursula Strandberg Timo Ilo Jarkko Akkanen Paula Kankaala Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i> Biomolecules ARA climate change <i>Chironomus riparius</i> desaturation EPA |
author_facet |
Ursula Strandberg Timo Ilo Jarkko Akkanen Paula Kankaala |
author_sort |
Ursula Strandberg |
title |
Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i> |
title_short |
Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i> |
title_full |
Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i> |
title_fullStr |
Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i> |
title_full_unstemmed |
Warming Decreases Bioconversion of Polyunsaturated Fatty Acids in Chironomid Larvae Maintained on Cyanobacterium <i>Microcystis</i> |
title_sort |
warming decreases bioconversion of polyunsaturated fatty acids in chironomid larvae maintained on cyanobacterium <i>microcystis</i> |
publisher |
MDPI AG |
series |
Biomolecules |
issn |
2218-273X |
publishDate |
2021-09-01 |
description |
Cyanobacteria dominance and warming have been suggested to decrease the production of polyunsaturated fatty acids (PUFA) in freshwater ecosystems. Physiological adaptations of poikilothermic animals to higher temperatures may further decrease PUFA levels in aquatic food webs. We conducted diet manipulation experiments to investigate the combined effects of dietary PUFA and warming on the proportions of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) in <i>Chironomus riparius</i>. The experimental diet consisted of a nontoxic cyanobacterium <i>Microcystis</i>, which contained C<sub>20</sub> PUFA: 20:3n-3, 20:4n-3, and 20:3n-6, but no EPA or ARA. Additionally, we used TetraMin<sup>®</sup> fish flakes as a control treatment. A temperature increase from 20 °C to 25 °C decreased the proportion of n-3 C<sub>20</sub> PUFA and the n-3/n-6 ratio in <i>Microcystis</i>. Diet manipulation experiments indicated that <i>Chironomus</i> desaturated dietary C<sub>20</sub> precursors to EPA and ARA, but warming decreased this bioconversion and resulted in lower levels of EPA and ARA in <i>Chironomus</i>. Warming did not alter the proportions of EPA and ARA in <i>Chironomus</i> larvae if these PUFA were readily available in the diet (TetraMin<sup>®</sup> control treatment). In conclusion, warming and cyanobacteria dominance may decrease the production and trophic transfer of physiologically important PUFA in freshwaters by (1) decreasing the n-3/n-6 ratio and the abundance of n-3 C<sub>20</sub> precursors in <i>Microcystis</i>, and (2) decreasing the bioconversion of n-3 and n-6 C<sub>20</sub> precursors to EPA and ARA in chironomids. These changes may have cascading effects throughout the food web and decrease the content of EPA in fish, potentially affecting its availability to humans. |
topic |
ARA climate change <i>Chironomus riparius</i> desaturation EPA |
url |
https://www.mdpi.com/2218-273X/11/9/1326 |
work_keys_str_mv |
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