Impact of Ice Algae on Inorganic Nutrients in Seawater and Sea Ice in Barrow Strait, NWT, Canada, During Spring

1990 ◽  
Vol 47 (7) ◽  
pp. 1402-1415 ◽  
Author(s):  
Glenn F. Cota ◽  
Jeffrey L. Anning ◽  
Leslie R. Harris ◽  
W. Glen Harrison ◽  
Ralph E. H. Smith
Keyword(s):  
Sea Ice ◽  
Surface Waters ◽  
Algal Biomass ◽  
Ice Sheet ◽  
Inorganic Nutrients ◽  
Ice Algae ◽  
High Biomass ◽  
Dissolved Nutrients ◽  
Particulate Nitrogen ◽  
Ice Water

Except in "bottom ice" (lowest few centimetres) and surface waters impacted by autotrophs, the major inorganic nutrients behave conservatively in seawater and sea ice. From mid- to late spring, steep and persistent nutrient gradients were observed in the "well-mixed surface layer" with minima near the ice–water interface. Nitrate, ammonium, and phosphate are highly concentrated in heavily colonized bottom ice relative to seawater and the remainder of the ice sheet; concentrations in darkened, weakly colonized bottom ice are similar to the ice sheet. These nutrients also display strong vertical stratification over millimetre scales. Nitrate and phosphate in the bottom ice layer display strong positive relationships with chlorophyll. The accumulation of these nutrients in bottom ice must be biologically mediated and constitutes a significant sink. In contrast, silicic acid concentrations in bottom ice are close to those expected for sea ice formed from the source seawater, are only weakly related to algal biomass, and vary much less seasonally. Ice algae are apparently shocked osmotically and release their intracellular pools of dissolved nutrients. Intracellular pools of nitrate averaged 1.4–9.5% of total particulate nitrogen. Nitrient stresses, during periods of high biomass and sluggish supply, may be alleviated by pooling.

scholarly journals Towards improved estimates of sea-ice algal biomass: experimental assessment of hyperspectral imaging cameras for under-ice studies

2017 ◽  
Vol 58 (75pt1) ◽  
pp. 68-77 ◽  
Author(s):  
Emiliano Cimoli ◽  
Arko Lucieer ◽  
Klaus M. Meiners ◽  
Lars Chresten Lund-Hansen ◽  
Fraser Kennedy ◽  
...  
Keyword(s):  
Sea Ice ◽  
Hyperspectral Imaging ◽  
Algal Biomass ◽  
Large Scale ◽  
Polar Regions ◽  
Ice Algae ◽  
Water Interface ◽  
Algae Biomass ◽  
Distribution Matching ◽  
Ice Water

ABSTRACTIce algae are a key component in polar marine food webs and have an active role in large-scale biogeochemical cycles. They remain extremely under-sampled due to the coarse nature of traditional point sampling methods compounded by the general logistical limitations of surveying in polar regions. This study provides a first assessment of hyperspectral imaging as an under-ice remote-sensing method to capture sea-ice algae biomass spatial variability at the ice/water interface. Ice-algal cultures were inoculated in a unique inverted sea-ice simulation tank at increasing concentrations over designated cylinder enclosures and sparsely across the ice/water interface. Hyperspectral images of the sea ice were acquired with a pushbroom sensor attaining 0.9 mm square pixel spatial resolution for three different spectral resolutions (1.7, 3.4, 6.7 nm). Image analysis revealed biomass distribution matching the inoculated chlorophyll a concentrations within each cylinder. While spectral resolutions >6 nm hindered biomass differentiation, 1.7 and 3.4 nm were able to resolve spatial variation in ice algal biomass implying a coherent sensor selection. The inverted ice tank provided a suitable sea-ice analogue platform for testing key parameters of the methodology. The results highlight the potential of hyperspectral imaging to capture sea-ice algal biomass variability at unprecedented scales in a non-invasive way.

scholarly journals Sea-ice associated carbon flux in Arctic spring

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
J. Ehrlich ◽  
B. A. Bluhm ◽  
I. Peeken ◽  
P. Massicotte ◽  
F. L. Schaafsma ◽  
...  
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Carbon Flux ◽  
Secondary Production ◽  
Environmental Changes ◽  
Ice Algae ◽  
Carbon Demand ◽  
Algal Material ◽  
Source Sink ◽  
Ice Water

The Svalbard region faces drastic environmental changes, including sea-ice loss and “Atlantification” of Arctic waters, caused primarily by climate warming. These changes result in shifts in the sea-ice-associated (sympagic) community structure, with consequences for the sympagic food web and carbon cycling. To evaluate the role of sympagic biota as a source, sink, and transmitter of carbon, we sampled pack ice and under-ice water (0–2 m) north of Svalbard in spring 2015 by sea-ice coring and under-ice trawling. We estimated biomass and primary production of ice algae and under-ice phytoplankton as well as biomass, carbon demand, and secondary production of sea-ice meiofauna (>10 µm) and under-ice fauna (>300 µm). Sea-ice meiofauna biomass (0.1–2.8 mg C m–2) was dominated by harpacticoid copepods (92%), nauplii (4%), and Ciliophora (3%). Under-ice fauna biomass (3.2–62.7 mg C m–2) was dominated by Calanus copepods (54%). Appendicularia contributed 23% through their high abundance at one station. Herbivorous sympagic fauna dominated the carbon demand across the study area, estimated at 2 mg C m–2 day–1 for ice algae and 4 mg C m–2 day–1 for phytoplankton. This demand was covered by the mean primary production of ice algae (11 mg C m–2 day–1) and phytoplankton (30 mg C m–2 day–1). Hence, potentially 35 mg C m–2 day–1 of algal material could sink from the sympagic realm to deeper layers. The demand of carnivorous under-ice fauna (0.3 mg C m–2 day–1) was barely covered by sympagic secondary production (0.3 mg C m–2 day–1). Our study emphasizes the importance of under-ice fauna for the carbon flux from sea ice to pelagic and benthic habitats and provides a baseline for future comparisons in the context of climate change.

Investigations of skeletal layer microstructure in the context of remote sensing of oil in sea ice

2017 ◽  
Vol 2017 (1) ◽  
pp. 2237-2255 ◽  
Author(s):  
Zoe R. Courville ◽  
Ross Lieb-Lappen ◽  
Keran Claffey ◽  
Bruce Elder
Keyword(s):  
Remote Sensing ◽  
Sea Ice ◽  
Ice Sheet ◽  
Sensor Data ◽  
The Arctic ◽  
Army Corps ◽  
Water Interface ◽  
Micro Ct ◽  
X Ray ◽  
Ice Water

ABSTRACT (2017-159) The Arctic Oil Spill Response Technology – Joint Industry Program (JIP) funded a controlled basin experiment in November 2014 to assess the relative capabilities of a variety of oil in ice remote sensing techniques. An 80-cm sheet of level salt-water ice was grown in the Test Basin facility at the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire. The basin ice was representative of natural level sea ice grown under quiescent conditions. This created a controlled baseline environment to compare different sensors with a manageable number of variables. The sensor testing spanned a two-month ice growth phase and a one-month decay/melt period. The detailed physical and electrical properties of the lab-grown ice sheet were monitored over the course of the experiment. Analysis of preliminary sensor data revealed that the skeletal layer--the soft, porous band of new ice crystals at the growing ice water interface--plays a significant role in the process of incorporation of oil into the ice sheet, with oil infiltration occurring between the small lamellae structures. In addition, the underwater sensors, particularly acoustic sensors, appeared to be very sensitive to skeletal layer properties, especially the surface roughness of the ice/water interface and the density of the skeletal layer. Preliminary X-ray micro-computed tomography (micro-CT) data collected as part of the experiment demonstrated a qualitative scale dependence of sensor response to the skeletal layer microstructure. We used a cold-hardened Bruker SkyScan 1173 micro-CT scanner, housed in a −10 °C cold room, to generate full 3-dimensional x-ray images of the sea ice samples. We have demonstrated that the system is capable of distinguishing areas of void space, brine, ice, and oil at 40 micron resolution. The micro-CT scans were used to characterize the skeletal layer of the ice, including measuring density, thickness, orientation and spacing of the lamellae at 39 – 71 micron voxel resolution. Characterizing the ice structure with high resolution micro-CT imaging may resolve some of the ambiguity in the sensor measurements and lead to improved accuracy of the numerical models that predict sensor performance in different oil and ice scenarios.

Bacterial dynamics in first year sea ice and underlying seawater of Saroma-ko Lagoon (Sea of Okhotsk, Japan) and Resolute Passage (High Canadian Arctic): Inhibitory effects of ice algae on bacterial dynamics

2000 ◽  
Vol 46 (7) ◽  
pp. 623-632 ◽  
Author(s):  
Patrick Monfort ◽  
Serge Demers ◽  
Maurice Levasseur
Keyword(s):  
Sea Ice ◽  
Algal Biomass ◽  
Bacterial Abundance ◽  
Canadian Arctic ◽  
Total Cell ◽  
First Year ◽  
Ice Algae ◽  
Inhibitory Effects ◽  
Bacterial Dynamics ◽  
Culturable Fraction

The seasonal development of bacterial abundance in first year bottom ice and underlying seawater were studied at Saroma-ko Lagoon in Hokkaido, Japan, and at Resolute Passage in the High Canadian Arctic during the algal bloom in spring 1992. The aim of this study was to evaluate whether the high algal concentrations reached during the bloom of ice algae have inhibitory effects on bacterial dynamics. Bacterial abundance (measured as total cell count and colony-forming units CFU) increased with the increase of the algal biomass up to 500 µg Chla·L-1in both locations. Culturable fraction (measured as the percentage of CFU counts versus the total cell counts) was between 7% and 22% at Saroma-ko, and approximately 0.08% at Resolute Passage. When algal biomass exceeded 500 µg of Chla·L-1, both bacterial abundance and culturable fraction decreased significantly. There was a maximum threshold of algal biomass (between 500 and 800 µg of Chla·L-1) after which bacterial dynamics become negatively coupled to the algal biomass. These results suggest that bactericidal and/or bacteriostatic compounds from these extremely high algal concentrations could explain the decrease in bacterial abundance and culturability in bottom ice observed after the ice algae bloom.Key words: bacteria, culturability, algae, inhibitory effects, sea ice, Arctic.

scholarly journals An Under-Ice Hyperspectral and RGB Imaging System to Capture Fine-Scale Biophysical Properties of Sea Ice

2019 ◽  
Vol 11 (23) ◽  
pp. 2860 ◽  
Author(s):  
Emiliano Cimoli ◽  
Klaus M. Meiners ◽  
Arko Lucieer ◽  
Vanessa Lucieer
Keyword(s):  
Sea Ice ◽  
Algal Biomass ◽  
Bottom Topography ◽  
Environmental Drivers ◽  
Future Research ◽  
Ice Algae ◽  
Digital Photogrammetry ◽  
Biophysical Properties ◽  
Algae Biomass ◽  
Non Invasive

Sea-ice biophysical properties are characterized by high spatio-temporal variability ranging from the meso- to the millimeter scale. Ice coring is a common yet coarse point sampling technique that struggles to capture such variability in a non-invasive manner. This hinders quantification and understanding of ice algae biomass patchiness and its complex interaction with some of its sea ice physical drivers. In response to these limitations, a novel under-ice sled system was designed to capture proxies of biomass together with 3D models of bottom topography of land-fast sea-ice. This system couples a pushbroom hyperspectral imaging (HI) sensor with a standard digital RGB camera and was trialed at Cape Evans, Antarctica. HI aims to quantify per-pixel chlorophyll-a content and other ice algae biological properties at the ice-water interface based on light transmitted through the ice. RGB imagery processed with digital photogrammetry aims to capture under-ice structure and topography. Results from a 20 m transect capturing a 0.61 m wide swath at sub-mm spatial resolution are presented. We outline the technical and logistical approach taken and provide recommendations for future deployments and developments of similar systems. A preliminary transect subsample was processed using both established and novel under-ice bio-optical indices (e.g., normalized difference indexes and the area normalized by the maximal band depth) and explorative analyses (e.g., principal component analyses) to establish proxies of algal biomass. This first deployment of HI and digital photogrammetry under-ice provides a proof-of-concept of a novel methodology capable of delivering non-invasive and highly resolved estimates of ice algal biomass in-situ, together with some of its environmental drivers. Nonetheless, various challenges and limitations remain before our method can be adopted across a range of sea-ice conditions. Our work concludes with suggested solutions to these challenges and proposes further method and system developments for future research.

Nutrients, algal biomass and communities in land-fast ice and seawater off Adélie Land (Antarctica)

2000 ◽  
Vol 12 (2) ◽  
pp. 160-171 ◽  
Author(s):  
Catherine Riaux-Gobin ◽  
Paul Tréguer ◽  
Michel Poulin ◽  
Gilles Vétion
Keyword(s):  
Sea Ice ◽  
Snow Cover ◽  
Algal Biomass ◽  
Open Water ◽  
Water Masses ◽  
Near Shore ◽  
Fast Ice ◽  
Pigment Concentrations ◽  
Cell Densities ◽  
Ice Water

Land-fast ice in the vicinity of Adélie Land was sampled during spring 1995. The ice was annual, thin, with no consistent snow cover, and exposed to oceanic conditions. Temporal and spatial variations of the vertical pigment distribution were studied in relation to environmental factors, during the break up of the ice. Different levels were sampled in the congelation ice and the platelet ice-like layer (PLI). Under-ice water and open water masses were also sampled. The algal biomass was greater in the PLI (24 ±14 μg chl a l−1 offshore and up to 9 mg chl a l−1 near-shore), than in the under-ice water, and fell to 0.9 ± 0.64 μg chl al−1 in open water masses. Homogenous low pigment concentrations were detected in the upper levels of congelation ice. A gradient was identified along a 7 km seaward transect, sampled in November, with the lowest biomass offshore. The integrated pigment concentrations in fast ice reached very high levels 500 mg chl a m−2 near the coast and 0.8 mg m−2 offshore), with apparently no relationship with either the ice thickness or snow cover. In the congelation ice nutrient concentrations were low and their distribution homogenous, whereas in the PLI high concentrations of nitrate (up to 100–300 μM NO3) and silicic acid [30–100 μM Si(OH)4] were detected, often related to high pigment concentrations and proximity to islands. The sea ice algae communities were diverse, but mostly composed of chain-forming and tube-dwelling pennate diatoms (Amphiprora, Berkeleya, Nitzschia and Navicula). Cell densities in PLI reached up to 1010 cells l−1. At very low biomass and cell densities 2 104 cells l−1) the phytoplankton also had a low diversity; some species were similar to those of the PLI, such as Navicula glaciei, but other were typically planktonic (Chaetoceros). At sea ice break-up it is estimated that a significant proportion of particulate matter (up to 0.5 g chl a m−2 near-shore) was transferred to the underlying water masses (on an average 15 t POC km−1 shoreline).

scholarly journals Sea-ice habitat minimizes grazing impact and predation risk for larval Antarctic krill

Polar Biology ◽  
2021 ◽  
Author(s):  
Carmen L. David ◽  
Fokje L. Schaafsma ◽  
Jan A. van Franeker ◽  
Evgeny A. Pakhomov ◽  
Brian P. V. Hunt ◽  
...  
Keyword(s):  
Sea Ice ◽  
Predation Risk ◽  
Water Column ◽  
Antarctic Krill ◽  
Standing Stock ◽  
Euphausia Superba ◽  
Grazing Impact ◽  
Water Interface ◽  
Winter Habitat ◽  
Ice Water

AbstractSurvival of larval Antarctic krill (Euphausia superba) during winter is largely dependent upon the presence of sea ice as it provides an important source of food and shelter. We hypothesized that sea ice provides additional benefits because it hosts fewer competitors and provides reduced predation risk for krill larvae than the water column. To test our hypothesis, zooplankton were sampled in the Weddell-Scotia Confluence Zone at the ice-water interface (0–2 m) and in the water column (0–500 m) during August–October 2013. Grazing by mesozooplankton, expressed as a percentage of the phytoplankton standing stock, was higher in the water column (1.97 ± 1.84%) than at the ice-water interface (0.08 ± 0.09%), due to a high abundance of pelagic copepods. Predation risk by carnivorous macrozooplankton, expressed as a percentage of the mesozooplankton standing stock, was significantly lower at the ice-water interface (0.83 ± 0.57%; main predators amphipods, siphonophores and ctenophores) than in the water column (4.72 ± 5.85%; main predators chaetognaths and medusae). These results emphasize the important role of sea ice as a suitable winter habitat for larval krill with fewer competitors and lower predation risk. These benefits should be taken into account when considering the response of Antarctic krill to projected declines in sea ice. Whether reduced sea-ice algal production may be compensated for by increased water column production remains unclear, but the shelter provided by sea ice would be significantly reduced or disappear, thus increasing the predation risk on krill larvae.

Subglacial sediment pathways and deglacial chronology of the northern Barents Sea Ice Sheet

Boreas ◽  
2017 ◽  
Vol 46 (4) ◽  
pp. 750-771 ◽  
Author(s):  
Kelly A. Hogan ◽  
Julian A. Dowdeswell ◽  
Claus-Dieter Hillenbrand ◽  
Werner Ehrmann ◽  
Riko Noormets ◽  
...  
Keyword(s):  
Sea Ice ◽  
Barents Sea ◽  
Ice Sheet
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