Spatial and temporal variability in the response of phytoplankton and prokaryotes to B-vitamin amendments in an upwelling system
<p>We experimentally evaluated the temporal (interday and interseason) and spatial variability in microbial plankton responses to vitamin B12 and/or B1 supply (solely or in combination with inorganic nutrients) in coastal and oceanic waters of the northeast Atlantic Ocean. Phytoplankton and, t...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2020-05-01
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Series: | Biogeosciences |
Online Access: | https://www.biogeosciences.net/17/2807/2020/bg-17-2807-2020.pdf |
Summary: | <p>We experimentally evaluated the temporal (interday and
interseason) and spatial variability in microbial plankton responses to
vitamin B12 and/or B1 supply (solely or in combination with inorganic
nutrients) in coastal and oceanic waters of the northeast Atlantic Ocean.
Phytoplankton and, to a lesser extent, prokaryotes were strongly limited by
inorganic nutrients. Interday variability in microbial plankton responses
to B vitamins was limited compared to interseason variability, suggesting
that B-vitamin availability might be partially controlled by factors
operating at seasonal scale. Chlorophyll <span class="inline-formula"><i>a</i></span> (Chl <span class="inline-formula"><i>a</i></span>) concentration and
prokaryote biomass (PB) significantly increased after B-vitamin amendments
in 13 % and 21 %, respectively, of the 216 cases (36 experiments <span class="inline-formula">×</span> 6 treatments). Most of these positive responses were produced by
treatments containing either B12 solely or B12 combined with B1 in oceanic
waters, which was consistent with the significantly lower average vitamin-B12 ambient concentrations compared to that in the coastal station. Negative
responses, implying a decrease in Chl <span class="inline-formula"><i>a</i></span> or PB, represented 21 % for
phytoplankton and 26 % for prokaryotes. Growth stimulation by B1 addition
was more frequent on prokaryotes than in phytoplankton, suggesting that B1
auxotrophy in the sampling area could be more widespread in prokaryotes than
in phytoplankton. Negative responses to B vitamins were generalized in
coastal surface waters in summer and were associated with a high contribution
of Flavobacteriales to the prokaryote community. This observation suggests
that the external supply of B12 and/or B1 may promote negative interactions
between microbial components when B-vitamin auxotrophs are abundant. The
microbial response patterns to B12 and/or B1 amendments were significantly
correlated with changes in the prokaryotic community composition,
highlighting the pivotal role of prokaryotes in B-vitamin cycling in marine
ecosystems.</p> |
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ISSN: | 1726-4170 1726-4189 |