scholarly journals Elevated temperature and decreased salinity both affect the biochemical composition of the Antarctic sea-ice diatom Nitzschia lecointei, but not increased pCO2

Polar Biology ◽  
2019 ◽  
Vol 42 (11) ◽  
pp. 2149-2164 ◽  
Author(s):  
Anders Torstensson ◽  
Carlos Jiménez ◽  
Anders K. Nilsson ◽  
Angela Wulff
Keyword(s):  
Climate Change ◽  
Lipid Peroxidation ◽  
Sea Ice ◽  
Ocean Acidification ◽  
Biochemical Composition ◽  
Fatty Acid Content ◽  
Separate Experiment ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
The Antarctic

Abstract Areas in western Antarctica are experiencing rapid climate change, where ocean warming results in more sea ice melt simultaneously as oceanic CO2 levels are increasing. In this study, we have tested how increased temperature (from −1.8 to 3 °C) and decreased salinity (from 35 to 20 and 10) synergistically affect the growth, photophysiology and biochemical composition of the Antarctic sea-ice diatom Nitzschia lecointei. In a separate experiment, we also addressed how ocean acidification (from 400 to 1000 µatm partial pressure of CO2) affects these key physiological parameters. Both positive and negative changes in specific growth rate, particulate organic carbon to particulate organic nitrogen ratio, chl a fluorescence kinetics, lipid peroxidation, carbohydrate content, protein content, fatty acid content and composition were observed when cells were exposed to warming and desalination. However, when cells were subjected to increased pCO2, only Fv/Fm, non-photochemical quenching and lipid peroxidation increased (by 3, 16 and 14%, respectively), and no other of the abovementioned biochemical properties were affected. These results suggest that changes in temperature and salinity may have more effects on the biochemical composition of N. lecointei than ocean acidification. Sea-ice algae are important component of polar food webs, and their nutritional quality may be affected as a result of altered environmental conditions due to climate change and sea ice melt.

scholarly journals Synergism between elevated <i>p</i>CO<sub>2</sub> and temperature on the Antarctic sea ice diatom <i>Nitzschia lecointei</i>

2013 ◽  
Vol 10 (10) ◽  
pp. 6391-6401 ◽  
Author(s):  
A. Torstensson ◽  
M. Hedblom ◽  
J. Andersson ◽  
M. X. Andersson ◽  
A. Wulff
Keyword(s):  
Growth Rate ◽  
Sea Ice ◽  
Ocean Acidification ◽  
Cold Water ◽  
Optimal Growth ◽  
Trophic Levels ◽  
Separate Experiment ◽  
Antarctic Sea Ice ◽  
Lipid Fatty Acid ◽  
The Antarctic

Abstract. Polar oceans are particularly susceptible to ocean acidification and warming. Diatoms play a significant role in sea ice biogeochemistry and provide an important food source to grazers in ice-covered oceans, especially during early spring. However, the ecophysiology of ice-living organisms has received little attention in terms of ocean acidification. In this study, the synergism between temperature and partial pressure of CO2 (pCO2) was investigated in relationship to the optimal growth temperature of the Antarctic sea ice diatom Nitzschia lecointei. Diatoms were kept in cultures at controlled levels of pCO2 (∼390 and ∼960 μatm) and temperature (−1.8 and 2.5 °C) for 14 days. Synergism between temperature and pCO2 was detected in growth rate and acyl lipid fatty acid (FA) content. Optimal growth rate was observed around 5 °C in a separate experiment. Carbon enrichment only promoted (6%) growth rate closer to the optimal growth, but not at the control temperature (−1.8 °C). At −1.8 °C and at ∼960 μatm pCO2, the total FA content was reduced relative to the ∼390 μatm treatment, although no difference between pCO2 treatments was observed at 2.5 °C. A large proportion (97%) of the total FAs comprised on average of polyunsaturated fatty acids (PUFA) at −1.8 °C. Cellular PUFA content was reduced at ∼960 relative to ∼390 μatm pCO2. Effects of carbon enrichment may be different depending on ocean warming scenario or season, e.g. reduced cellular FA content in response to elevated CO2 at low temperatures only, reflected as reduced food quality for higher trophic levels. Synergy between warming and acidification may be particularly important in polar areas since a narrow thermal window generally limits cold-water organisms.

scholarly journals Impacts of Interactive Stratospheric Chemistry on Antarctic and Southern Ocean Climate Change in the Goddard Earth Observing System, Version 5 (GEOS-5)

2016 ◽  
Vol 29 (9) ◽  
pp. 3199-3218 ◽  
Author(s):  
Feng Li ◽  
Yury V. Vikhliaev ◽  
Paul A. Newman ◽  
Steven Pawson ◽  
Judith Perlwitz ◽  
...  
Keyword(s):  
Climate Change ◽  
Southern Ocean ◽  
Sea Ice ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Meridional Overturning Circulation ◽  
Stratospheric Chemistry ◽  
Earth Observing System ◽  
Antarctic Sea Ice ◽  
The Antarctic

Abstract Stratospheric ozone depletion plays a major role in driving climate change in the Southern Hemisphere. To date, many climate models prescribe the stratospheric ozone layer’s evolution using monthly and zonally averaged ozone fields. However, the prescribed ozone underestimates Antarctic ozone depletion and lacks zonal asymmetries. This study investigates the impact of using interactive stratospheric chemistry instead of prescribed ozone on climate change simulations of the Antarctic and Southern Ocean. Two sets of 1960–2010 ensemble transient simulations are conducted with the coupled ocean version of the Goddard Earth Observing System Model, version 5: one with interactive stratospheric chemistry and the other with prescribed ozone derived from the same interactive simulations. The model’s climatology is evaluated using observations and reanalysis. Comparison of the 1979–2010 climate trends between these two simulations reveals that interactive chemistry has important effects on climate change not only in the Antarctic stratosphere, troposphere, and surface, but also in the Southern Ocean and Antarctic sea ice. Interactive chemistry causes stronger Antarctic lower stratosphere cooling and circumpolar westerly acceleration during November–January. It enhances stratosphere–troposphere coupling and leads to significantly larger tropospheric and surface westerly changes. The significantly stronger surface wind stress trends cause larger increases of the Southern Ocean meridional overturning circulation, leading to year-round stronger ocean warming near the surface and enhanced Antarctic sea ice decrease.

scholarly journals Variability in Antarctic sea ice from 1998-2017

2018 ◽  
Author(s):  
Zhankai Wu ◽  
Xingdong Wang
Keyword(s):  
Sea Ice ◽  
First Year ◽  
Concentration Data ◽  
Sea Ice Concentration ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Ice Concentration ◽  
The Antarctic ◽  
Melt Duration ◽  
Multiyear Ice

This study was based on the daily sea ice concentration data from the National Snow and Ice Data Center (Cooperative Institute for Research in Environmental Sciences, Boulder, CO, USA) from 1998 to 2017. The Antarctic sea ice was analysed from the total sea ice area (SIA), first year ice area, first year ice melt duration, and multiyear ice area. On a temporal scale, the changes in sea ice parameters were studied over the whole 20 years and for two 10-year periods. The results showed that the total SIA increased by 0.0083×106 km2 yr-1 (+2.07% dec-1) between 1998 and 2017. However, the total SIA in the two 10-year periods showed opposite trends, in which the total SIA increased by 0.026×106 km2 yr-1 between 1998 and 2007 and decreased by 0.0707×106 km2 yr-1 from 2008 to 2017. The first year ice area increased by 0.0059×106 km2 yr-1 and the melt duration decreased by 0.0908 days yr-1 between 1998 and 2017. The multiyear ice area increased by 0.0154×106 km2 yr-1 from 1998 to 2017, and the increase in the last 10 years was about 12.1% more than that in the first 10 years. On a spatial scale, the Entire Antarctica was divided into two areas, namely West Antarctica (WA) and East Antarctica (EA), according to the spatial change rate of sea ice concentration. The results showed that WA had clear warming in recent years; the total sea ice and multiyear ice areas showed a decreasing trend; multiyear ice area sharply decreased and reached the lowest value in 2017, and accounted for only about 10.1% of the 20-year average. However, the total SIA and multiyear ice area all showed an increased trend in EA, in which the multiyear ice area increased by 0.0478×106 km2 yr-1. Therefore, Antarctic sea ice presented an increasing trend, but there were different trends in WA and EA. Different sea ice parameters in WA and EA showed an opposite trend from 1998 to 2007. However, the total SIA, first year ice area, and multiyear ice area all showed a decreasing trend from 2008-2017, especially the total sea ice and first year ice, which changed almost the same in 2014-2017. In summary, although the Antarctic sea ice has increased slightly over time, it has shown a decreasing trend in recent years.

Effects of ocean acidification on the physiological performance and carbon production of the Antarctic sea ice diatom Nitzschia sp. ICE-H

2017 ◽  
Vol 120 (1-2) ◽  
pp. 184-191 ◽  
Author(s):  
Chang-Feng Qu ◽  
Fang-Ming Liu ◽  
Zhou Zheng ◽  
Yi-Bin Wang ◽  
Xue-Gang Li ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ocean Acidification ◽  
Physiological Performance ◽  
Carbon Production ◽  
Antarctic Sea Ice ◽  
The Antarctic

scholarly journals Observed Antarctic sea ice expansion reproduced in a climate model after correcting biases in sea ice drift velocity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shantong Sun ◽  
Ian Eisenman
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Drift Velocity ◽  
Climate Model ◽  
Future Climate Change ◽  
Antarctic Sea Ice ◽  
Ice Drift ◽  
Recent Climate ◽  
Sea Ice Drift ◽  
The Antarctic

AbstractThe Antarctic sea ice area expanded significantly during 1979–2015. This is at odds with state-of-the-art climate models, which typically simulate a receding Antarctic sea ice cover in response to increasing greenhouse forcing. Here, we investigate the hypothesis that this discrepancy between models and observations occurs due to simulation biases in the sea ice drift velocity. As a control we use the Community Earth System Model (CESM) Large Ensemble, which has 40 realizations of past and future climate change that all undergo Antarctic sea ice retreat during recent decades. We modify CESM to replace the simulated sea ice velocity field with a satellite-derived estimate of the observed sea ice motion, and we simulate 3 realizations of recent climate change. We find that the Antarctic sea ice expands in all 3 of these realizations, with the simulated spatial structure of the expansion bearing resemblance to observations. The results suggest that the reason CESM has failed to capture the observed Antarctic sea ice expansion is due to simulation biases in the sea ice drift velocity, implying that an improved representation of sea ice motion is crucial for more accurate sea ice projections.

Microzooplankton composition in the winter sea ice of the Weddell Sea

2017 ◽  
Vol 29 (4) ◽  
pp. 299-310 ◽  
Author(s):  
Marina Monti-Birkenmeier ◽  
Tommaso Diociaiuti ◽  
Serena Fonda Umani ◽  
Bettina Meyer
Keyword(s):  
Sea Ice ◽  
Ice Cores ◽  
Complete Loss ◽  
Weddell Sea ◽  
Late Winter ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Carbon Biomass ◽  
The Antarctic ◽  
Carbon Concentrations

AbstractSympagic microzooplankton were studied during late winter in the northern Weddell Sea for diversity, abundance and carbon biomass. Ice cores were collected on an ice floe along three dive transects and seawater was taken from under the ice through the central dive hole from which all transects were connected. The areal and vertical microzooplankton distributions in the ice and water were compared. Abundance (max. 1300 ind. l-1) and biomass (max. 28.2 µg C l-1) were high in the ice cores and low in the water below the sea ice (max. 19 ind. l-1, 0.15 µg C l-1, respectively). The highest abundances were observed in the bottom 10 cm of the ice cores. The microzooplankton community within the sea ice comprised mainly aloricate ciliates, foraminifers and micrometazoans. In winter, microzooplankton represent an important fraction of the sympagic community in the Antarctic sea ice. They can potentially control microalgal production and contribute to particulate organic carbon concentrations when released into the water column during the ice melt in spring. Continued reduction of the sea ice may undermine the roles of microzooplankton, leading to a reduction or complete loss of diversity, abundance and biomass of these sympagic protists.

The microalga Phaeocystis antarctica is tolerant to salinity and metal mixture toxicity interactions

2021 ◽  
Author(s):  
Darren John Koppel ◽  
Nicholas Whitelaw ◽  
Merrin S. Adams ◽  
Catherine K King ◽  
Dianne F Jolley
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Marine Environment ◽  
Mixture Toxicity ◽  
Metal Mixture ◽  
Ice Melt ◽  
Phaeocystis Antarctica ◽  
The Antarctic

Salinity in the Antarctic nearshore marine environment is seasonally dynamic and climate change is driving greater variability through altered sea ice seasons, ocean evaporation rates, and increased terrestrial ice melt....

The role of Antarctic sea ice in global climate change

1996 ◽  
Vol 20 (4) ◽  
pp. 371-401 ◽  
Author(s):  
Edward Hanna
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Global Climate Change ◽  
Global Climate ◽  
The Arctic ◽  
Antarctic Sea Ice ◽  
Current State ◽  
Ocean Models ◽  
State Of Research ◽  
The Antarctic

Taking a distinct interdisciplinary focus, a critical view is presented of the current state of research concerning Antarctic sea-ice / atmosphere / ocean interaction and its effect on climate on the interannual timescale, with particular regard to anthropogenic global warming. Sea-ice formation, morphology, thickness, extent, seasonality and distribution are introduced as vital factors in climatic feedbacks. Sea-ice / atmosphere interaction is next discussed, emphas izing its meteorological and topographical influences and the effects of and on polar cyclonic activity. This leads on to the central theme of sea ice in global climate change, which contains critiques of sea-ice climatic feedbacks, current findings on the representation of these feedbacks in global climatic models, and to what extent they are corroborated by observational evidence. Sea-ice / ocean interaction is particularly important. This is discussed with special reference to polynyas and leads, and the use of suitably coupled sea-ice / ocean models. A brief review of several possible climatic forcing factors is presented, which most highly rates a postulated ENSO-Antarctic sea-ice link. Sea-ice / atmosphere / ocean models need to be validated by adequate observations, both from satellites and ground based. In particular, models developed in the Arctic, where the observational network allows more reasonable validation, can be applied to the Antarctic in suitably modified form so as to account for unique features of the Antarctic cryosphere. Benefits in climatic modelling will be gained by treating Antarctic sea ice as a fully coupled component of global climate.

scholarly journals Variability in Antarctic sea ice from 1998-2017

2018 ◽  
Author(s):  
Zhankai Wu ◽  
Xingdong Wang
Keyword(s):  
Sea Ice ◽  
First Year ◽  
Concentration Data ◽  
Sea Ice Concentration ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Ice Concentration ◽  
The Antarctic ◽  
Melt Duration ◽  
Multiyear Ice

This study was based on the daily sea ice concentration data from the National Snow and Ice Data Center (Cooperative Institute for Research in Environmental Sciences, Boulder, CO, USA) from 1998 to 2017. The Antarctic sea ice was analysed from the total sea ice area (SIA), first year ice area, first year ice melt duration, and multiyear ice area. On a temporal scale, the changes in sea ice parameters were studied over the whole 20 years and for two 10-year periods. The results showed that the total SIA increased by 0.0083×106 km2 yr-1 (+2.07% dec-1) between 1998 and 2017. However, the total SIA in the two 10-year periods showed opposite trends, in which the total SIA increased by 0.026×106 km2 yr-1 between 1998 and 2007 and decreased by 0.0707×106 km2 yr-1 from 2008 to 2017. The first year ice area increased by 0.0059×106 km2 yr-1 and the melt duration decreased by 0.0908 days yr-1 between 1998 and 2017. The multiyear ice area increased by 0.0154×106 km2 yr-1 from 1998 to 2017, and the increase in the last 10 years was about 12.1% more than that in the first 10 years. On a spatial scale, the Entire Antarctica was divided into two areas, namely West Antarctica (WA) and East Antarctica (EA), according to the spatial change rate of sea ice concentration. The results showed that WA had clear warming in recent years; the total sea ice and multiyear ice areas showed a decreasing trend; multiyear ice area sharply decreased and reached the lowest value in 2017, and accounted for only about 10.1% of the 20-year average. However, the total SIA and multiyear ice area all showed an increased trend in EA, in which the multiyear ice area increased by 0.0478×106 km2 yr-1. Therefore, Antarctic sea ice presented an increasing trend, but there were different trends in WA and EA. Different sea ice parameters in WA and EA showed an opposite trend from 1998 to 2007. However, the total SIA, first year ice area, and multiyear ice area all showed a decreasing trend from 2008-2017, especially the total sea ice and first year ice, which changed almost the same in 2014-2017. In summary, although the Antarctic sea ice has increased slightly over time, it has shown a decreasing trend in recent years.

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