TY - JOUR
T1 - Patterns of CO2 concentration and inorganic carbon limitation of phytoplankton biomass in agriculturally eutrophic lakes
AU - Zagarese, Horacio E.
AU - Sagrario, María de los Ángeles González
AU - Wolf-Gladrow, Dieter
AU - Nõges, Peeter
AU - Nõges, Tiina
AU - Kangur, Külli
AU - Matsuzaki, Shin Ichiro S.
AU - Kohzu, Ayato
AU - Vanni, Michael J.
AU - Özkundakci, Deniz
AU - Echaniz, Santiago A.
AU - Vignatti, Alicia
AU - Grosman, Fabián
AU - Sanzano, Pablo
AU - Van Dam, Bryce
AU - Knoll, Lesley B.
N1 - Funding Information:
This work resulted from a Fellowship held by H. Zagarese at the Hanse-Wissenschaftskolleg Institute for Advanced Study, Delmenhorst, Germany.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2021/2/15
Y1 - 2021/2/15
N2 - Lake eutrophication is a pervasive problem globally, particularly serious in agricultural and densely populated areas. Whenever nutrients nitrogen and phosphorus do not limit phytoplankton growth directly, high growth rates will rapidly lead to biomass increases causing self-shading and light-limitation, and eventually CO2 depletion. The paradigm of phytoplankton limitation by nutrients and light is so pervasively established, that the lack of nutrient limitation is ordinarily interpreted as sufficient evidence for the condition of light limitation, without considering the possibility of limitation by inorganic carbon. Here, we firstly evaluated how frequently CO2 undersaturation occurs in a set of eutrophic lakes in the Pampa plains. Our results confirm that conditions of CO2 undersaturation develop much more frequently (yearly 34%, summer 44%) in these agriculturally impacted lakes than in deep, temperate lakes in forested watersheds. Secondly, we used Generalized Additive Models to fit trends in CO2 concentration considering three drivers: total incident irradiance, chlorophyll a concentration, and lake depth; in eight multi-year datasets from eutrophic lakes from Europe, North and South America, Asia and New Zealand. CO2 depletion was more often observed at high irradiance levels, and shallow water. CO2 depletion also occurred at high chlorophyll concentration. Finally, we identified occurrences of light- and carbon-limitation at the whole-lake scale. The different responses of chlorophyll a and CO2 allowed us to develop criteria for detecting conditions of CO2 limitation. For the first time, we provided whole-lake evidence of carbon limitation of phytoplankton biomass. CO2 increases and eutrophication represent two major and converging environmental problems that have additive and contrasting effects, promoting phytoplankton, and also leading to carbon depletion. Their interactions deserve further exploration and imaginative approaches to deal with their effects.
AB - Lake eutrophication is a pervasive problem globally, particularly serious in agricultural and densely populated areas. Whenever nutrients nitrogen and phosphorus do not limit phytoplankton growth directly, high growth rates will rapidly lead to biomass increases causing self-shading and light-limitation, and eventually CO2 depletion. The paradigm of phytoplankton limitation by nutrients and light is so pervasively established, that the lack of nutrient limitation is ordinarily interpreted as sufficient evidence for the condition of light limitation, without considering the possibility of limitation by inorganic carbon. Here, we firstly evaluated how frequently CO2 undersaturation occurs in a set of eutrophic lakes in the Pampa plains. Our results confirm that conditions of CO2 undersaturation develop much more frequently (yearly 34%, summer 44%) in these agriculturally impacted lakes than in deep, temperate lakes in forested watersheds. Secondly, we used Generalized Additive Models to fit trends in CO2 concentration considering three drivers: total incident irradiance, chlorophyll a concentration, and lake depth; in eight multi-year datasets from eutrophic lakes from Europe, North and South America, Asia and New Zealand. CO2 depletion was more often observed at high irradiance levels, and shallow water. CO2 depletion also occurred at high chlorophyll concentration. Finally, we identified occurrences of light- and carbon-limitation at the whole-lake scale. The different responses of chlorophyll a and CO2 allowed us to develop criteria for detecting conditions of CO2 limitation. For the first time, we provided whole-lake evidence of carbon limitation of phytoplankton biomass. CO2 increases and eutrophication represent two major and converging environmental problems that have additive and contrasting effects, promoting phytoplankton, and also leading to carbon depletion. Their interactions deserve further exploration and imaginative approaches to deal with their effects.
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U2 - 10.1016/j.watres.2020.116715
DO - 10.1016/j.watres.2020.116715
M3 - Article
C2 - 33310445
AN - SCOPUS:85097636266
SN - 0043-1354
VL - 190
JO - Water Research
JF - Water Research
M1 - 116715
ER -