Under-ice measurements of suspended particulate matters using ADCP and LISST-Holo

Ha, Ho Kyung; Kim, Yong Hoon; Lee, Hyun Jung; Hwang, Byongjun; Joo, Hyoung Min

doi:10.1007/s12601-015-0008-2

Cited by 10 publications

(5 citation statements)

References 46 publications

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“…The reexamination of datasets from previous expeditions over the past two decades suggests that UIBs may have already had a circumpolar distribution. High concentrations of phytoplankton biomass under Arctic sea ice (typically with >50% coverage) have been reported in areas as widespread as Resolute Passage and Allen Bay in the Canadian Arctic Archipelago (Michel et al, 1996;Fortier et al, 2002;Duerksen et al, 2014;Galindo et al, 2014Galindo et al, , 2015Galindo et al, , 2016Mundy et al, 2014), Baffin Bay (Hussherr et al, 2017;Oziel et al, 2019), the Greenland Sea (Mayot et al, 2018), the Barents Sea (Strass and Nöthig, 1996;Assmy et al, 2017;Pavlov et al, 2017;Kauko et al, 2019), the Laptev Sea (Lalande et al, 2014), the Chukchi Sea (Yager et al, 2001;Arrigo et al, 2012Arrigo et al, , 2014Ha et al, 2015;Hill et al, 2018), and the Central Arctic (Laney et al, 2014;Boles et al, 2020). Many locations where UIBs were observed had first year sea ice, which was not the case in the 1980s when multi-year sea-ice was more prevalent (Figure 11).…”

Section: Discussionmentioning

confidence: 99%

Environmental drivers of under-ice phytoplankton bloom dynamics in the Arctic Ocean

Ardyna

Mundy

Mills

et al. 2020

Elementa: Science of the Anthropocene

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The decline of sea-ice thickness, area, and volume due to the transition from multi-year to first-year sea ice has improved the under-ice light environment for pelagic Arctic ecosystems. One unexpected and direct consequence of this transition, the proliferation of under-ice phytoplankton blooms (UIBs), challenges the paradigm that waters beneath the ice pack harbor little planktonic life. Little is known about the diversity and spatial distribution of UIBs in the Arctic Ocean, or the environmental drivers behind their timing, magnitude, and taxonomic composition. Here, we compiled a unique and comprehensive dataset from seven major research projects in the Arctic Ocean (11 expeditions, covering the spring sea-ice-covered period to summer ice-free conditions) to identify the environmental drivers responsible for initiating and shaping the magnitude and assemblage structure of UIBs. The temporal dynamics behind UIB formation are related to the ways that snow and sea-ice conditions impact the under-ice light field. In particular, the onset of snowmelt significantly increased under-ice light availability (>0.1–0.2 mol photons m–2 d–1), marking the concomitant termination of the sea-ice algal bloom and initiation of UIBs. At the pan-Arctic scale, bloom magnitude (expressed as maximum chlorophyll a concentration) was predicted best by winter water Si(OH)4 and PO43– concentrations, as well as Si(OH)4:NO3– and PO43–:NO3– drawdown ratios, but not NO3– concentration. Two main phytoplankton assemblages dominated UIBs (diatoms or Phaeocystis), driven primarily by the winter nitrate:silicate (NO3–:Si(OH)4) ratio and the under-ice light climate. Phaeocystis co-dominated in low Si(OH)4 (i.e., NO3:Si(OH)4 molar ratios >1) waters, while diatoms contributed the bulk of UIB biomass when Si(OH)4 was high (i.e., NO3:Si(OH)4 molar ratios <1). The implications of such differences in UIB composition could have important ramifications for Arctic biogeochemical cycles, and ultimately impact carbon flow to higher trophic levels and the deep ocean.

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Section: Discussionmentioning

confidence: 99%

Environmental drivers of under-ice phytoplankton bloom dynamics in the Arctic Ocean

Ardyna

Mundy

Mills

et al. 2020

Elementa: Science of the Anthropocene

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“…For drifting and transect data collections, central latitude and longitude locations are used. Additional to Table 1, studies that demonstrated indirect evidence of UIBs (e.g., Lalande et al, 2014;Ha et al, 2015;Hussherr et al, 2017) are plotted.…”

Section: Changing Under-ice Light Regime Precursor To Under-ice Bloomentioning

confidence: 99%

Under-Ice Phytoplankton Blooms: Shedding Light on the “Invisible” Part of Arctic Primary Production

et al. 2020

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The growth of phytoplankton at high latitudes was generally thought to begin in open waters of the marginal ice zone once the highly reflective sea ice retreats in spring, solar elevation increases, and surface waters become stratified by the addition of sea-ice melt water. In fact, virtually all recent large-scale estimates of primary production in the Arctic Ocean (AO) assume that phytoplankton production in the water column under sea ice is negligible. However, over the past two decades, an emerging literature showing significant under-ice phytoplankton production on a pan-Arctic scale has challenged our paradigms of Arctic phytoplankton ecology and phenology. This evidence, which builds on previous, but scarce reports, requires the Arctic scientific community to change its perception of traditional AO phenology and urgently revise it. In particular, it is essential to better comprehend, on small and large scales, the changing and variable icescapes, the under-ice light field and biogeochemical cycles during the transition from sea-ice covered to ice-free Arctic waters. Here, we provide a baseline of our current knowledge of under-ice blooms (UIBs), by defining their ecology and their environmental setting, but also their regional peculiarities (in terms of occurrence, magnitude, and assemblages), which is shaped by a complex AO. To this end, a multidisciplinary approach, i.e., combining expeditions and modern autonomous technologies, satellite, and modeling analyses, has been used to provide an overview of this pan-Arctic phenological feature, which will become increasingly important in future marine Arctic biogeochemical cycles.

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“…The LI screening method is optimized for a high-SSC environment where frequent resuspension of cohesive sediments is observed. In offshore areas (e.g., Ha et al, 2015;Many et al, 2019), where the sediment supply is significantly limited, the possibility of hologram contamination caused by the overlapping concentric rings would be considerably low. In this case, the criterion of LI to screen the contamination might be higher than that proposed in this study.…”

Section: Limitationsmentioning

confidence: 99%

Practical Method to Screen Contaminated Holograms of Flocs Using Light Intensity

et al. 2021

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Submergible digital holographic camera can measure the in situ size and shape of suspended particles, such as complex flocs and biological organisms, without disturbance. As the number of particles in the water column increases, overlapping concentric rings (interference patterns) can contaminate the holographic images. Using light intensity (LI), this study proposes a practical method to assess the degree of contamination and screen out contaminated images. The outcomes from image processing support that LI normalized on a gray scale of 0 (black) to 255 (white) can be a reliable criterion for defining the contamination boundary. Results found that as LI increased, the shape of the particle size distribution shifted from a positively skewed to a normal distribution. When LI was lower than approximately 80, owing to the distortion of particle properties, the settling velocities derived from the contaminated holograms with mosaic patterns were underestimated compared to those from the uncontaminated holograms. The proposed method can contribute to a more accurate estimation of the transport and behavior of cohesive sediments in shallow estuarine environments.

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Under-ice measurements of suspended particulate matters using ADCP and LISST-Holo

Cited by 10 publications

References 46 publications

Environmental drivers of under-ice phytoplankton bloom dynamics in the Arctic Ocean

Environmental drivers of under-ice phytoplankton bloom dynamics in the Arctic Ocean

Under-Ice Phytoplankton Blooms: Shedding Light on the “Invisible” Part of Arctic Primary Production

Practical Method to Screen Contaminated Holograms of Flocs Using Light Intensity

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