Biogenic silica production and diatom dynamics in the Svalbard region during spring
Diatoms are generally the dominant contributors to the Arctic Ocean spring bloom, which is a key event in regional food webs in terms of capacity for secondary production and organic matter export. Dissolved silicic acid is an obligate nutrient for diatoms and has been declining in the European Arct...
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Published in | Biogeosciences Vol. 15; no. 21; pp. 6503 - 6517 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Katlenburg-Lindau
Copernicus GmbH
06.11.2018
European Geosciences Union (EGU) Copernicus Publications |
Subjects | |
Online Access | Get full text |
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Summary: | Diatoms are generally the dominant contributors to the Arctic Ocean spring
bloom, which is a key event in regional food webs in terms of capacity for
secondary production and organic matter export. Dissolved silicic acid is an
obligate nutrient for diatoms and has been declining in the European Arctic
since the early 1990s. The lack of regional silicon cycling information
precludes understanding the consequences of such changes for diatom
productivity during the Arctic spring bloom. This study communicates the
results from a cruise in the European Arctic around Svalbard, which reports the
first concurrent data on biogenic silica production and export, export of
diatom cells, the degree of kinetic limitation by ambient silicic acid, and
diatom contribution to primary production. Regional biogenic silica
production rates were significantly lower than those achievable in the
Southern Ocean and silicic acid concentration limited the biogenic silica
production rate in 95 % of samples. Compared to diatoms in the Atlantic
subtropical gyre, regional diatoms are less adapted for silicic acid uptake
at low concentration, and at some stations during the present study, silicon
kinetic limitation may have been intense enough to limit diatom growth. Thus,
silicic acid can play a critical role in diatom spring bloom dynamics. The
diatom contribution to primary production was variable, ranging from
<10 % to ∼100 % depending on the bloom stage and
phytoplankton composition. While there was agreement with previous studies
regarding the export rate of diatom cells, we observed significantly elevated
biogenic silica export. Such a discrepancy can be resolved if a higher
fraction of the diatom material exported during our study was modified by
zooplankton grazers. This study provides the most direct evidence to date
suggesting the important coupling of the silicon and carbon cycles during the
spring bloom in the European Arctic. |
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Bibliography: | Biogeosciences |
ISSN: | 1726-4189 1726-4170 1726-4189 |
DOI: | 10.5194/bg-15-6503-2018 |