---
_id: '12232'
abstract:
- lang: eng
text: We investigate the "macronutrient-access hypothesis", which states that the
balance between stoichiometric macronutrient demand and accessible macronutrients
controls nutrient assimilation by aquatic heterotrophs. Within this hypothesis,
we consider bioavailable dissolved organic carbon (bDOC), reactive nitrogen (N)
and reactive phosphorus (P) to be the macronutrients accessible to heterotrophic
assimilation. Here, reactive N and P are the sums of dissolved inorganic N (nitrate-N,
nitrite-N, ammonium-N), soluble-reactive P (SRP), and bioavailable dissolved organic
N (bDON) and P (bDOP). Previous data from various freshwaters suggests this hypothesis,
yet clear experimental support is missing. We assessed this hypothesis in a proof-of-concept
experiment for waters from four small agricultural streams. We used seven different
bDOC:reactive N and bDOC:reactive P ratios, induced by seven levels of alder leaf
leachate addition. With these treatments and a stream-water specific bacterial
inoculum, we conducted a 3-day experiment with three independent replicates per
combination of stream water, treatment, and sampling occasion. Here, we extracted
dissolved organic matter (DOM) fluorophores by measuring excitation-emission matrices
with subsequent parallel factor decomposition (EEM-PARAFAC). We assessed the true
bioavailability of DOC, DON, and the DOM fluorophores as the concentration difference
between the beginning and end of each experiment. Subsequently, we calculated
the bDOC and bDON concentrations based on the bioavailable EEM-PARAFAC fluorophores,
and compared the calculated bDOC and bDON concentrations to their true bioavailability.
Due to very low DOP concentrations, the DOP determination uncertainty was high,
and we assumed DOP to be a negligible part of the reactive P. For bDOC and bDON,
the true bioavailability measurements agreed with the same fractions calculated
indirectly from bioavailable EEM-PARAFAC fluorophores (bDOC r2 = 0.96, p < 0.001;
bDON r2 = 0.77, p < 0.001). Hence we could predict bDOC and bDON concentrations
based on the EEM-PARAFAC fluorophores. The ratios of bDOC:reactive N (sum of bDON
and DIN) and bDOC:reactive P (equal to SRP) exerted a strong, predictable stoichiometric
control on reactive N and P uptake (R2 = 0.80 and 0.83). To define zones of C:N:P
(co-)limitation of heterotrophic assimilation, we used a novel ternary-plot approach
combining our data with literature data on C:N:P ranges of bacterial biomass.
Here, we found a zone of maximum reactive N uptake (C:N:P approx. > 114: < 9:1),
reactive P uptake (C:N:P approx. > 170:21: < 1) and reactive N and P co-limitation
of nutrient uptake (C:N:P approx. > 204:14:1). The “macronutrient-access hypothesis”
links ecological stoichiometry and biogeochemistry, and may be of importance for
nutrient uptake in many freshwater ecosystems. However, this experiment is only
a starting point and this hypothesis needs to be corroborated by further experiments
for more sites, by in-situ studies, and with different DOC sources.
author:
- first_name: Daniel
full_name: Graeber, Daniel
last_name: Graeber
- first_name: Youngdoung
full_name: Tenzin, Youngdoung
last_name: Tenzin
- first_name: Marc
full_name: Stutter, Marc
last_name: Stutter
- first_name: Gabriele
full_name: Weigelhofer, Gabriele
last_name: Weigelhofer
- first_name: Tom
full_name: Shatwell, Tom
id: '86424'
last_name: Shatwell
orcid: 0000-0002-4520-7916
- first_name: Wolf
full_name: von Tümpling, Wolf
last_name: von Tümpling
- first_name: Jörg
full_name: Tittel, Jörg
last_name: Tittel
- first_name: Alexander
full_name: Wachholz, Alexander
last_name: Wachholz
- first_name: Dietrich
full_name: Borchardt, Dietrich
last_name: Borchardt
citation:
ama: 'Graeber D, Tenzin Y, Stutter M, et al. Bioavailable DOC: reactive nutrient
ratios control heterotrophic nutrient assimilation—An experimental proof of the
macronutrient-access hypothesis. Biogeochemistry : an international journal
. 2021;155(1):1-20. doi:10.1007/s10533-021-00809-4'
apa: 'Graeber, D., Tenzin, Y., Stutter, M., Weigelhofer, G., Shatwell, T., von Tümpling,
W., Tittel, J., Wachholz, A., & Borchardt, D. (2021). Bioavailable DOC: reactive
nutrient ratios control heterotrophic nutrient assimilation—An experimental proof
of the macronutrient-access hypothesis. Biogeochemistry : An International
Journal , 155(1), 1–20. https://doi.org/10.1007/s10533-021-00809-4'
bjps: 'Graeber D et al. (2021) Bioavailable DOC: Reactive Nutrient
Ratios Control Heterotrophic Nutrient Assimilation—An Experimental Proof of the
Macronutrient-Access Hypothesis. Biogeochemistry : an international journal
155, 1–20.'
chicago: 'Graeber, Daniel, Youngdoung Tenzin, Marc Stutter, Gabriele Weigelhofer,
Tom Shatwell, Wolf von Tümpling, Jörg Tittel, Alexander Wachholz, and Dietrich
Borchardt. “Bioavailable DOC: Reactive Nutrient Ratios Control Heterotrophic Nutrient
Assimilation—An Experimental Proof of the Macronutrient-Access Hypothesis.” Biogeochemistry :
An International Journal 155, no. 1 (2021): 1–20. https://doi.org/10.1007/s10533-021-00809-4.'
chicago-de: 'Graeber, Daniel, Youngdoung Tenzin, Marc Stutter, Gabriele Weigelhofer,
Tom Shatwell, Wolf von Tümpling, Jörg Tittel, Alexander Wachholz und Dietrich
Borchardt. 2021. Bioavailable DOC: reactive nutrient ratios control heterotrophic
nutrient assimilation—An experimental proof of the macronutrient-access hypothesis.
Biogeochemistry : an international journal 155, Nr. 1: 1–20. doi:10.1007/s10533-021-00809-4,
.'
din1505-2-1: 'Graeber,
Daniel ; Tenzin, Youngdoung
; Stutter, Marc ; Weigelhofer,
Gabriele ; Shatwell, Tom
; von Tümpling, Wolf ; Tittel,
Jörg ; Wachholz, Alexander
; u. a.: Bioavailable DOC: reactive nutrient ratios control heterotrophic
nutrient assimilation—An experimental proof of the macronutrient-access hypothesis.
In: Biogeochemistry : an international journal Bd. 155. Cham, Springer (2021),
Nr. 1, S. 1–20'
havard: 'D. Graeber, Y. Tenzin, M. Stutter, G. Weigelhofer, T. Shatwell, W. von
Tümpling, J. Tittel, A. Wachholz, D. Borchardt, Bioavailable DOC: reactive nutrient
ratios control heterotrophic nutrient assimilation—An experimental proof of the
macronutrient-access hypothesis, Biogeochemistry : An International Journal .
155 (2021) 1–20.'
ieee: 'D. Graeber et al., “Bioavailable DOC: reactive nutrient ratios control
heterotrophic nutrient assimilation—An experimental proof of the macronutrient-access
hypothesis,” Biogeochemistry : an international journal , vol. 155, no.
1, pp. 1–20, 2021, doi: 10.1007/s10533-021-00809-4.'
mla: 'Graeber, Daniel, et al. “Bioavailable DOC: Reactive Nutrient Ratios Control
Heterotrophic Nutrient Assimilation—An Experimental Proof of the Macronutrient-Access
Hypothesis.” Biogeochemistry : An International Journal , vol. 155, no.
1, 2021, pp. 1–20, https://doi.org/10.1007/s10533-021-00809-4.'
short: 'D. Graeber, Y. Tenzin, M. Stutter, G. Weigelhofer, T. Shatwell, W. von Tümpling,
J. Tittel, A. Wachholz, D. Borchardt, Biogeochemistry : An International Journal 155
(2021) 1–20.'
ufg: 'Graeber, Daniel u. a.: Bioavailable DOC: reactive nutrient ratios control
heterotrophic nutrient assimilation—An experimental proof of the macronutrient-access
hypothesis, in: Biogeochemistry : an international journal 155 (2021),
H. 1, S. 1–20.'
van: 'Graeber D, Tenzin Y, Stutter M, Weigelhofer G, Shatwell T, von Tümpling W,
et al. Bioavailable DOC: reactive nutrient ratios control heterotrophic nutrient
assimilation—An experimental proof of the macronutrient-access hypothesis. Biogeochemistry :
an international journal . 2021;155(1):1–20.'
date_created: 2024-12-08T20:21:39Z
date_updated: 2024-12-09T11:21:31Z
department:
- _id: DEP8022
doi: 10.1007/s10533-021-00809-4
extern: '1'
intvolume: ' 155'
issue: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.1007/s10533-021-00809-4
oa: '1'
page: 1-20
place: Cham
publication: 'Biogeochemistry : an international journal '
publication_identifier:
eissn:
- 1573-515X
issn:
- 0168-2563
publication_status: published
publisher: 'Springer '
quality_controlled: '1'
status: public
title: 'Bioavailable DOC: reactive nutrient ratios control heterotrophic nutrient
assimilation—An experimental proof of the macronutrient-access hypothesis'
type: scientific_journal_article
user_id: '83781'
volume: 155
year: '2021'
...