DOI: 10.18710/cfabrj
title: Biogenic silica production and diatom dynamics in the Svalbard region during spring 2016

description: &lt;p&gt;Raw data used in the publication of "Biogenic silica production and diatom dynamics in the Svalbard region during spring 2016".&lt;/p&gt;

&lt;p&gt;ARCEx.
The Research Centre for Arctic Petroleum Exploration, ARCEx, is a research collaboration between academia and industry with support from the Research Council and Norwegian authorities. Through a common effort, the project contributes to the understanding of the geology and resource potential of the high north, the development of new geophysical exploration techniques suitable for the Arctic and new models for environmental risk connected to operations in the north. Education and training is an integrated part of ARCEx. ARCEx is hosted by UiT The Arctic University of Norway in Tromsø.&lt;/p&gt;

&lt;p&gt;Cruise goal and duration.
The overarching goal of the ARCEx cruise was to study the pelagic and benthic ecosystem during Arctic spring bloom scenarios in fjords at western Svalbard (van Mijenfjorden and Hornsund), a coastal scenario (Storfjorden) and the western Barents Sea (in the Arctic influenced Erik Eriksen Strait, the Polar Front and at an Atlantic influenced location). This study was conducted onboard the FF Helmer Hanssen between 17 and 29 May 2016 with Dr. Ingrid Wiedmann serving as Chief Scientist.&lt;p&gt;&lt;/p&gt;

&lt;p&gt;Data collection.
All samples reported in this data set were collected either using a water-column CTD Rosette sampler with Niskin bottles or short-duration sediment traps. The CTD package was a Seabird Electronics (SBE) 911plus with a photosynthetically active radiation sensor (Biospherical/Licor, SN 1060). Discreet samples were collected at targeted depths using 5-L Niskin samplers secured to the CTD Rosette system. Once on deck, water was sampled directly from the Niskin samplers to be processed for the measurements and methods described. The vertical flux of particulates was assessed by filtering water from the short-term (&lt;1 day) deployed sediment traps (KC Denmark). Sediment trap cylinders (~72mm internal diameter, ~450mm length, ~1:8 L volume) were deployed at three to seven depths ranging between 20 and 150–200 m, based on bathymetry. At the two fjord stations (van Mijenfjorden, Hornsund), the sediment trap array was anchored to the bottom. In the more open regions of the drift ice covered Arctic station (Erik Eriksen Strait) and the open water stations in the Atlantic waters in the wester Barents Sea, the sediment trap array was anchored to an ice-floe and freely drifting, respectively. After recovery of the sediment traps, all cylinder contents at a particular depth were pooled in a acid-cleaned container, homogenized and subsampled for the measurements and methods described.&lt;/p&gt;
description: Abstract. 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 &lt; 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.