Changes in the lipid composition of Antarctic sea-ice diatom communities during a spring bloom: an indication of community physiological status

1989 ◽  
Vol 1 (2) ◽  
pp. 133-140 ◽  
Author(s):  
Peter D. Nichols ◽  
Anna C. Palmisano ◽  
Mark S. Rayner ◽  
Glen A. Smith ◽  
David C. White
Keyword(s):  
Sea Ice ◽  
Lipid Composition ◽  
Spring Bloom ◽  
Natural Populations ◽  
Coastal Sediments ◽  
Physiological Status ◽  
Austral Spring ◽  
Biological Source ◽  
Antarctic Sea Ice ◽  
Algal Groups

The lipid composition of natural populations of diatoms in the sea ice at McMurdo Sound was determined during the austral spring bloom of 1985, using and Iatroscan TLC–FID system. The major lipid classes in all samples were polar lipids (including phospholipid, glycolipid and chlorophyll) and triacylglycerol, with lesser proportions of free fatty acids. Total lipid increased through November and early December, reaching a maximum (3300 mg m−2 at Cape Armitage and 1800 mg m−2 at Erebus Ice Tongue) c. one week after the chlorophyll a maxima. This increase was largely attributable to a corresponding increase in triacylglycerol. At the lipid maxima, triacylglycerol/polar lipid ratios in the range 1.0 to 2.5 were observed. The dynamic variations in lipid class abundances indicate that profound changes in the physiology of sea-ice diatoms are occurring throughout the spring bloom. A range of sterols (C26–C30) were detected; 24-methylenecholesterol, brassicasterol and 24-ethylcholesterol were the major sterols at the Cape Armitage and Erebus sites. The similarity of the sterol profiles to those of Antarctic freshwater algal communities strongly indicates diatoms as a more probable source of C29 sterols in the freshwater lakes than cyanobacteria or other algal groups. The hydrocarbons isolated from sea-ice diatoms at all sites were dominated by two unsaturated components, n−C21:6 and a diunsaturated isoprenoid C25 alkene. Until this study, no biological source had been validated for the isoprenoid C25:2 diene, even though it has been detected in many estuarine and coastal sediments.

Fatty acid, sterol and hydrocarbon composition of Antarctic sea ice diatom communities during the spring bloom in McMurdo Sound

1993 ◽  
Vol 5 (3) ◽  
pp. 271-278 ◽  
Author(s):  
David S. Nichols ◽  
Peter D. Nichols ◽  
Cornelius W. Sullivan
Keyword(s):  
Fatty Acids ◽  
Sea Ice ◽  
Spring Bloom ◽  
Lipid Fraction ◽  
Hydrocarbon Composition ◽  
Sampling Period ◽  
Coastal Sediments ◽  
Austral Spring ◽  
Mcmurdo Sound ◽  
Total Fatty Acids

The lipid composition of microalgal communities dominated by diatoms collected from the sea ice at three locations within McMurdo Sound during the austral spring bloom of 1989/90, was determined using gas chromatography (GC) and GC mass spectrometry. A range of C27-C29 sterols were detected. The major sterols found at the three sites were 24-methylcholesta-5, 22E-diene-3β-ol (Cape Armitage); trans-22-dehydrocholesterol, 24-ethylcholesterol and 24-methylenecholesta (Erebus Ice Tongue); and 24-methylenecholesterol (Cape Royds). The difference in sterol profiles is believed to reflect the differing species composition at each site. The high relative levels (as % of total) of 24-ethylcholesterol at the Erebus Ice Tongue site (possibly related to Amphiprora kufferathii) supports the proposal that diatoms are a more probable source of C29 sterols in Antarctic lakes than are other algal groups or cyanobacteria. Changes in sterol composition over the course of the bloom were evident at the Cape Armitage site, particularly within the cellular free-lipid fraction. The major fatty acids identified were 14:0, 16:0, 16:1ω7c, 16:4ω1 and 20:5ω3 (Cape Armitage and Erebus Ice tongue sites); 16:0, 16:1ω7c and 20:5ω3 (Cape Royds site). All sites demonstrated high levels of PUFA (40–50% of total fatty acids), with an average 20:5ω3 level of 21% Erebus Ice Tongue, 20% Cape Royds, and 17% Cape Armitage. Variation was also observed in the percentage of 20:5ω3 for the Cape Armitage community over the sampling period. Levels of 22:6ω3 were between 0.4 and 1% of total fatty acids for the three sites. A C25:2 isoprenoid hydrocarbon was present in samples from all sites, adding further evidence to the proposal that diatoms are probably a source of this and related isoprenoid alkenes in marine and coastal sediments.

Conditions leading to the unprecedented low Antarctic sea ice extent during the 2016 austral spring season

2017 ◽  
Vol 44 (17) ◽  
pp. 9008-9019 ◽  
Author(s):  
Malte F. Stuecker ◽  
Cecilia M. Bitz ◽  
Kyle C. Armour
Keyword(s):  
Sea Ice ◽  
Spring Season ◽  
Austral Spring ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice

Biochemical composition and photosynthate distribution in sea ice microalgae of McMurdo Sound, Antarctica: evidence for nutrient stress during the spring bloom

1992 ◽  
Vol 4 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Michael P. Lizotte ◽  
Cornelius W. Sullivan
Keyword(s):  
Sea Ice ◽  
Spring Bloom ◽  
Natural Populations ◽  
Nutrient Status ◽  
Microalgal Biomass ◽  
Mcmurdo Sound ◽  
Nutrient Influx ◽  
Allocation Patterns ◽  
Photosynthate Allocation ◽  
Photosynthate Distribution

The nutrient status of microalgae inhabiting sea ice in McMurdo Sound, Antarctica was evaluated during the peak and decline of the spring bloom in November and December. Natural populations of microalgae were analysed for C, N, chlorophyll a, protein, lipid, polysaccharide, and low-molecular-weight carbohydrate content, and for the distribution of 14C-labelled photosynthate into macromolecular fractions. Ratios of N:C and protein to carbohydrate (PR:CHO) were similar to values reported for nutrient-limited phytoplankton. Biochemical ratios and 14C-photosynthate allocation patterns suggest that microalgae from congelation ice habitats may be more nutrient-stressed than those from underlying platelet ice habitats. This trend would be consistent with the presumed gradient of seawater nutrient influx through the platelet layer to the bottom congelation ice habitat. Microalgae from congelation ice subjected to an experimental depletion of nutrients (particularly nitrate) showed decreased N:C, PR:CHO, and allocation of 14C-photosynthate to proteins. This evidence suggests that sea ice microalgae are nutrient-stressed during the peak and decline of the spring bloom in McMurdo Sound, which presumably begins when microalgal biomass concentrations and demands for growth reach or exceed the rate of nutrient supply from underlying seawater.

Occurrence of novel C30 sterols in Antarctic sea-ice diatom communities during a spring bloom

1990 ◽  
Vol 15 (5) ◽  
pp. 503-508 ◽  
Author(s):  
Peter D. Nichols ◽  
Anna C. Palmisano ◽  
Mark S. Rayner ◽  
Glen A. Smith ◽  
David C. White
Keyword(s):  
Sea Ice ◽  
Spring Bloom ◽  
Antarctic Sea Ice ◽  
Diatom Communities

scholarly journals The Early 1990s Change in ENSO–PSA–SAM Relationships and Its Impact on Southern Hemisphere Climate

2015 ◽  
Vol 28 (23) ◽  
pp. 9393-9408 ◽  
Author(s):  
Jin-Yi Yu ◽  
Houk Paek ◽  
Eric S. Saltzman ◽  
Tong Lee
Keyword(s):  
Sea Ice ◽  
Southern Hemisphere ◽  
Air Temperature ◽  
Southern Oscillation ◽  
Phase Relationship ◽  
Surface Air Temperature ◽  
Central Pacific ◽  
Austral Spring ◽  
Antarctic Sea Ice ◽  
The Antarctic

Abstract This study uncovers an early 1990s change in the relationships between El Niño–Southern Oscillation (ENSO) and two leading modes of the Southern Hemisphere (SH) atmospheric variability: the southern annular mode (SAM) and the Pacific–South American (PSA) pattern. During austral spring, while the PSA maintained a strong correlation with ENSO throughout the period 1948–2014, the SAM–ENSO correlation changed from being weak before the early 1990s to being strong afterward. Through the ENSO connection, PSA and SAM became more in-phase correlated after the early 1990s. The early 1990s is also the time when ENSO changed from being dominated by the eastern Pacific (EP) type to being dominated by the central Pacific (CP) type. Analyses show that, while the EP ENSO can excite only the PSA, the CP ENSO can excite both the SAM and PSA through tropospheric and stratospheric pathway mechanisms. The more in-phase relationship between SAM and PSA impacted the post-1990s Antarctic climate in at least two aspects: 1) a stronger Antarctic sea ice dipole structure around the Amundsen–Bellingshausen Seas due to intensified geopotential height anomalies over the region and 2) a shift in the phase relationships of surface air temperature anomalies among East Antarctica, West Antarctica, and the Antarctic Peninsula. These findings imply that ENSO–Antarctic climate relations depend on the dominant ENSO type and that ENSO forcing has become more important to the Antarctic sea ice and surface air temperature variability in the past two decades and will in the coming decades if the dominance of CP ENSO persists.

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