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Exploring the distance between nitrogen and phosphorus limitation in mesotrophic surface waters using a sensitive bioassay.
Hrustic, Enis, Lignell, Risto, Riebesell, Ulf and Thingstad, Tron Frede
(2017)
Exploring the distance between nitrogen and phosphorus limitation in mesotrophic surface waters using a sensitive bioassay.
Biogeosciences (BG), 14
(2).
pp. 379-387.
DOI 10.5194/bg-14-379-2017.
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Abstract
The balance in microbial net consumption of nitrogen and phosphorus was investigated in samples collected in two mesotrophic coastal environments: the Baltic Sea (Tvärminne field station) and the North Sea (Espegrend field station). For this, we have refined a bioassay based on the response in alkaline phosphatase activity (APA) over a matrix of combinations in nitrogen and phosphorus additions. This assay not only provides information on which element (N or P) is the primary limiting nutrient, but also gives a quantitative estimate for the excess of the secondary limiting element (P+ or N+, respectively), as well as the ratio of balanced net consumption of added N and P over short timescales (days). As expected for a Baltic Sea late spring–early summer situation, the Tvärminne assays (n = 5) indicated N limitation with an average P+ = 0.30 ± 0.10 µM-P, when incubated for 4 days. For short incubations (1–2 days), the Espegrend assays indicated P limitation, but the shape of the response surface changed with incubation time, resulting in a drift in parameter estimates toward N limitation. Extrapolating back to zero incubation time gave P limitation with N+ ≈ 0.9 µM-N. The N : P ratio (molar) of nutrient net consumption varied considerably between investigated locations: from 2.3 ± 0.4 in the Tvärminne samples to 13 ± 5 and 32 ± 3 in two samples from Espegrend. Our assays included samples from mesocosm acidification experiments, but statistically significant effects of ocean acidification were not found by this method.
Document Type: | Article |
---|---|
Funder compliance: | info:eu-repo/grantAgreement/EC/FP7/603773 |
Research affiliation: | OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography |
Refereed: | Yes |
Open Access Journal?: | Yes |
Publisher: | Copernicus Publications (EGU) |
Projects: | OCEAN-CERTAIN, SOPRAN, BIOACID, Future Ocean |
Date Deposited: | 03 Apr 2017 10:47 |
Last Modified: | 06 Feb 2020 09:09 |
URI: | https://oceanrep.geomar.de/id/eprint/37381 |
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