Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers

Abstract After strong fertilization in the 20th century, many deep lakes in Central Europe are again nutrient poor due to long-lasting restoration (re-oligotrophication). In line with reduced phosphorus and nitrogen loadings, total organismic productivity decreased and lakes have now historically lo...

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Autores principales:	Yana Yankova, Stefan Neuenschwander, Oliver Köster, Thomas Posch
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/5dfd651ed98e4b57ae0a039c24a3d81b
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spelling	oai:doaj.org-article:5dfd651ed98e4b57ae0a039c24a3d81b2021-12-02T15:06:27ZAbrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers10.1038/s41598-017-13159-92045-2322https://doaj.org/article/5dfd651ed98e4b57ae0a039c24a3d81b2017-10-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-13159-9https://doaj.org/toc/2045-2322Abstract After strong fertilization in the 20th century, many deep lakes in Central Europe are again nutrient poor due to long-lasting restoration (re-oligotrophication). In line with reduced phosphorus and nitrogen loadings, total organismic productivity decreased and lakes have now historically low nutrient and biomass concentrations. This caused speculations that restoration was overdone and intended fertilizations are needed to ensure ecological functionality. Here we show that recent re-oligotrophication processes indeed accelerated, however caused by lake warming. Rising air temperatures strengthen thermal stabilization of water columns which prevents thorough turnover (holomixis). Reduced mixis impedes down-welling of oxygen rich epilimnetic (surface) and up-welling of phosphorus and nitrogen rich hypolimnetic (deep) water. However, nutrient inputs are essential for algal spring blooms acting as boost for annual food web successions. We show that repeated lack (since 1977) and complete stop (since 2013) of holomixis caused drastic epilimnetic phosphorus depletions and an absence of phytoplankton spring blooms in Lake Zurich (Switzerland). By simulating holomixis in experiments, we could induce significant vernal algal blooms, confirming that there would be sufficient hypolimnetic phosphorus which presently accumulates due to reduced export. Thus, intended fertilizations are highly questionable, as hypolimnetic nutrients will become available during future natural or artificial turnovers.Yana YankovaStefan NeuenschwanderOliver KösterThomas PoschNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-9 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Yana Yankova Stefan Neuenschwander Oliver Köster Thomas Posch Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
description	Abstract After strong fertilization in the 20th century, many deep lakes in Central Europe are again nutrient poor due to long-lasting restoration (re-oligotrophication). In line with reduced phosphorus and nitrogen loadings, total organismic productivity decreased and lakes have now historically low nutrient and biomass concentrations. This caused speculations that restoration was overdone and intended fertilizations are needed to ensure ecological functionality. Here we show that recent re-oligotrophication processes indeed accelerated, however caused by lake warming. Rising air temperatures strengthen thermal stabilization of water columns which prevents thorough turnover (holomixis). Reduced mixis impedes down-welling of oxygen rich epilimnetic (surface) and up-welling of phosphorus and nitrogen rich hypolimnetic (deep) water. However, nutrient inputs are essential for algal spring blooms acting as boost for annual food web successions. We show that repeated lack (since 1977) and complete stop (since 2013) of holomixis caused drastic epilimnetic phosphorus depletions and an absence of phytoplankton spring blooms in Lake Zurich (Switzerland). By simulating holomixis in experiments, we could induce significant vernal algal blooms, confirming that there would be sufficient hypolimnetic phosphorus which presently accumulates due to reduced export. Thus, intended fertilizations are highly questionable, as hypolimnetic nutrients will become available during future natural or artificial turnovers.
format	article
author	Yana Yankova Stefan Neuenschwander Oliver Köster Thomas Posch
author_facet	Yana Yankova Stefan Neuenschwander Oliver Köster Thomas Posch
author_sort	Yana Yankova
title	Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
title_short	Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
title_full	Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
title_fullStr	Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
title_full_unstemmed	Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers
title_sort	abrupt stop of deep water turnover with lake warming: drastic consequences for algal primary producers
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/5dfd651ed98e4b57ae0a039c24a3d81b
work_keys_str_mv	AT yanayankova abruptstopofdeepwaterturnoverwithlakewarmingdrasticconsequencesforalgalprimaryproducers AT stefanneuenschwander abruptstopofdeepwaterturnoverwithlakewarmingdrasticconsequencesforalgalprimaryproducers AT oliverkoster abruptstopofdeepwaterturnoverwithlakewarmingdrasticconsequencesforalgalprimaryproducers AT thomasposch abruptstopofdeepwaterturnoverwithlakewarmingdrasticconsequencesforalgalprimaryproducers
_version_	1718388451420667904

Abrupt stop of deep water turnover with lake warming: Drastic consequences for algal primary producers

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