Late Summer Frazil Ice‐Associated Algal Blooms around Antarctica

DeJong, Hans B.; Dunbar, Robert B.; Lyons, E. A.

doi:10.1002/2017gl075472

Cited by 13 publications

(9 citation statements)

References 37 publications

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“…As shown in Figure 15 and consistent with the associated single-cell biomass of the two phytoplankton groups, the late sea-ice growth in 2017 resulted in a generally lower Chl-a burden than in 1998 for the same period. Dejong and others (2017, 2018) have recently looked at late-summer frazil ice-associated algal blooms around Antarctica using daily MODIS visible spectral band satellite imagery. They produced a map of the percent of years between 2003 and 2017, where polynyas around Antarctica in March appear green from high photosynthetic productivity on the satellite images.…”

Section: Resultsmentioning

confidence: 98%

Physical and biological properties of early winter Antarctic sea ice in the Ross Sea

et al. 2020

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This work presents the results of physical and biological investigations at 27 biogeochemical stations of early winter sea ice in the Ross Sea during the 2017 PIPERS cruise. Only two similar cruises occurred in the past, in 1995 and 1998. The year 2017 was a specific year, in that ice growth in the Central Ross Sea was considerably delayed, compared to previous years. These conditions resulted in lower ice thicknesses and Chl-a burdens, as compared to those observed during the previous cruises. It also resulted in a different structure of the sympagic algal community, unusually dominated by Phaeocystis rather than diatoms. Compared to autumn-winter sea ice in the Weddell Sea (AWECS cruise), the 2017 Ross Sea pack ice displayed similar thickness distribution, but much lower snow cover and therefore nearly no flooding conditions. It is shown that contrasted dynamics of autumnal-winter sea-ice growth between the Weddell Sea and the Ross Sea impacted the development of the sympagic community. Mean/median ice Chl-a concentrations were 3–5 times lower at PIPERS, and the community status there appeared to be more mature (decaying?), based on Phaeopigments/Chl-a ratios. These contrasts are discussed in the light of temporal and spatial differences between the two cruises.

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Section: Resultsmentioning

confidence: 98%

Physical and biological properties of early winter Antarctic sea ice in the Ross Sea

et al. 2020

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“…When it reaches the bottom or gets in contact with resuspended sediments, it can incorporate sediments or macronutrients such as iron (30,(39)(40)(41), which are then transported by ice floes and released when the ice melts (41), possibly leading to high biological productivity (42). Alternatively, frazil ice could itself induce algal blooms as green frazil ice in major Antarctic polynyas, among which the CDP is one of the most active areas of frazil ice-associated algal production (43,44). This might be related to the fact that the CDP is the most prominent area of deep frazil ice.…”

Section: Implications Of the Dominant Underwater Frazil Icementioning

confidence: 99%

Dominant frazil ice production in the Cape Darnley polynya leading to Antarctic Bottom Water formation

et al. 2022

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Antarctic Bottom Water (AABW) occupies the abyssal layer of the world ocean and contributes to the global overturning circulation. It originates from dense shelf water, which forms from brine rejection during sea ice production. An important region of AABW formation has been identified off the Cape Darnley polynya. However, it remains unclear why and how high ice production leads to AABW formation. Using moored acoustic measurements and a satellite microwave algorithm, we reveal that underwater frazil ice dominates in the polynya. This underwater ice formation prevents heat-insulating surface-cover ice forming, thereby enabling efficient ice production. The high ice production in the nearshore and longer residence times create high-salinity source water for the AABW. Underwater frazil ice occurs as long as strong winds continue and occasionally penetrates depths of at least 80 m. Deep-penetrating frazil ice is particularly prominent in this polynya, while it also occurs in other Antarctic coastal polynyas.

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“…We note that our description of the drivers of the seasonal and vertical distribution of Chla is specific for thermodynamically grown landfast sea ice. Recent work by Lieser et al (2015) and DeJong et al (2018) provide evidence for the occurrence of frazil-ice associated algal blooms in offshore ice production areas of the Southern Ocean during late summer/early autumn. These blooms develop under much more dynamic conditions; that is, they are ultimately stimulated by strong winds (DeJong et al, 2017).…”

Section: Vertical Distribution Of Chlamentioning

confidence: 99%

Chlorophyll‐a in Antarctic Landfast Sea Ice: A First Synthesis of Historical Ice Core Data

et al. 2018

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Historical sea ice core chlorophyll‐a (Chla) data are used to describe the seasonal, regional, and vertical distribution of ice algal biomass in Antarctic landfast sea ice. The analyses are based on the Antarctic Fast Ice Algae Chlorophyll‐a data set, a compilation of currently available sea ice Chla data from landfast sea ice cores collected at circum‐Antarctic nearshore locations between 1970 and 2015. Ice cores were typically sampled from thermodynamically grown first‐year ice and have thin snow depths (mean = 0.052 ± 0.097 m). The data set comprises 888 ice cores, including 404 full vertical profile cores. Integrated ice algal Chla biomass (range: <0.1–219.9 mg/m2, median = 4.4 mg/m2, interquartile range = 9.9 mg/m2) peaks in late spring and shows elevated levels in autumn. The seasonal Chla development is consistent with the current understanding of physical drivers of ice algal biomass, including the seasonal cycle of irradiance and surface temperatures driving landfast sea ice growth and melt. Landfast ice regions with reported platelet ice formation show maximum ice algal biomass. Ice algal communities in the lowermost third of the ice cores dominate integrated Chla concentrations during most of the year, but internal and surface communities are important, particularly in winter. Through comparison of biomass estimates based on different sea ice sampling strategies, that is, analysis of full cores versus bottom‐ice section sampling, we identify biases in common sampling approaches and provide recommendations for future survey programs: for example, the need to sample fast ice over its entire thickness and to measure auxiliary physicochemical parameters.

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Late Summer Frazil Ice‐Associated Algal Blooms around Antarctica

Cited by 13 publications

References 37 publications

Physical and biological properties of early winter Antarctic sea ice in the Ross Sea

Physical and biological properties of early winter Antarctic sea ice in the Ross Sea

Dominant frazil ice production in the Cape Darnley polynya leading to Antarctic Bottom Water formation

Chlorophyll‐a in Antarctic Landfast Sea Ice: A First Synthesis of Historical Ice Core Data

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