Decline in plankton diversity and carbon flux with reduced sea ice extent along the Western Antarctic Peninsula

AbstractSince the middle of the past century, the Western Antarctic Peninsula has warmed rapidly with a significant loss of sea ice but the impacts on plankton biodiversity and carbon cycling remain an open question. Here, using a 5-year dataset of eukaryotic plankton DNA metabarcoding, we assess changes in biodiversity and net community production in this region. Our results show that sea-ice extent is a dominant factor influencing eukaryotic plankton community composition, biodiversity, and net community production. Species richness and evenness decline with an increase in sea surface temperature (SST). In regions with low SST and shallow mixed layers, the community was dominated by a diverse assemblage of diatoms and dinoflagellates. Conversely, less diverse plankton assemblages were observed in waters with higher SST and/or deep mixed layers when sea ice extent was lower. A genetic programming machine-learning model explained up to 80% of the net community production variability at the Western Antarctic Peninsula. Among the biological explanatory variables, the sea-ice environment associated plankton assemblage is the best predictor of net community production. We conclude that eukaryotic plankton diversity and carbon cycling at the Western Antarctic Peninsula are strongly linked to sea-ice conditions.

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Spring–summer net community production, new production, particle export and related water column biogeochemical processes in the marginal sea ice zone of the Western Antarctic Peninsula 2012–2014

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2017.0177 ◽

2018 ◽

Vol 376 (2122) ◽

pp. 20170177 ◽

Cited By ~ 12

Author(s):

Hugh W. Ducklow ◽

Michael R. Stukel ◽

Rachel Eveleth ◽

Scott C. Doney ◽

Tim Jickells ◽

...

Keyword(s):

Sea Ice ◽

Primary Production ◽

Water Column ◽

Antarctic Peninsula ◽

Net Primary Production ◽

Western Antarctic Peninsula ◽

New Production ◽

Net Community Production ◽

Particle Export ◽

Community Production

New production (New P, the rate of net primary production (NPP) supported by exogenously supplied limiting nutrients) and net community production (NCP, gross primary production not consumed by community respiration) are closely related but mechanistically distinct processes. They set the carbon balance in the upper ocean and define an upper limit for export from the system. The relationships, relative magnitudes and variability of New P (from 15 NO 3 – uptake), O 2 : argon-based NCP and sinking particle export (based on the 238 U : 234 Th disequilibrium) are increasingly well documented but still not clearly understood. This is especially true in remote regions such as polar marginal ice zones. Here we present a 3-year dataset of simultaneous measurements made at approximately 50 stations along the Western Antarctic Peninsula (WAP) continental shelf in midsummer (January) 2012–2014. Net seasonal-scale changes in water column inventories (0–150 m) of nitrate and iodide were also estimated at the same stations. The average daily rates based on inventory changes exceeded the shorter-term rate measurements. A major uncertainty in the relative magnitude of the inventory estimates is specifying the start of the growing season following sea-ice retreat. New P and NCP(O 2 ) did not differ significantly. New P and NCP(O 2 ) were significantly greater than sinking particle export from thorium-234. We suggest this is a persistent and systematic imbalance and that other processes such as vertical mixing and advection of suspended particles are important export pathways. This article is part of the theme issue ‘The marine system of the west Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

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Specific eukaryotic plankton are good predictors of net community production in the Western Antarctic Peninsula

Scientific Reports ◽

10.1038/s41598-017-14109-1 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 7

Author(s):

Yajuan Lin ◽

Nicolas Cassar ◽

Adrian Marchetti ◽

Carly Moreno ◽

Hugh Ducklow ◽

...

Keyword(s):

Antarctic Peninsula ◽

Western Antarctic Peninsula ◽

Net Community Production ◽

Community Production

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Interannual variability in net community production at the Western Antarctic Peninsula region (1997–2014)

Journal of Geophysical Research Oceans ◽

10.1002/2015jc011378 ◽

2016 ◽

Vol 121 (7) ◽

pp. 4748-4762 ◽

Cited By ~ 9

Author(s):

Zuchuan Li ◽

Nicolas Cassar ◽

Kuan Huang ◽

Hugh Ducklow ◽

Oscar Schofield

Keyword(s):

Interannual Variability ◽

Antarctic Peninsula ◽

Western Antarctic Peninsula ◽

Net Community Production ◽

Community Production

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Holocene climate variations in the western Antarctic Peninsula: evidence for sea ice extent predominantly controlled by changes in insolation and ENSO variability

Climate of the Past ◽

10.5194/cp-9-1431-2013 ◽

2013 ◽

Vol 9 (4) ◽

pp. 1431-1446 ◽

Cited By ~ 47

Author(s):

J. Etourneau ◽

L. G. Collins ◽

V. Willmott ◽

J.-H. Kim ◽

L. Barbara ◽

...

Keyword(s):

Sea Ice ◽

Water Column ◽

Antarctic Peninsula ◽

Primary Productivity ◽

Climatic Factors ◽

Southern Oscillation ◽

Western Antarctic Peninsula ◽

Deep Basin ◽

Sea Ice Extent ◽

Ice Conditions

Abstract. The West Antarctic ice sheet is particularly sensitive to global warming and its evolution and impact on global climate over the next few decades remains difficult to predict. In this context, investigating past sea ice conditions around Antarctica is of primary importance. Here, we document changes in sea ice presence, upper water column temperatures (0–200 m) and primary productivity over the last 9000 yr BP (before present) in the western Antarctic Peninsula (WAP) margin from a sedimentary core collected in the Palmer Deep Basin. Employing a multi-proxy approach, based on the combination of two biomarkers proxies (highly branched isoprenoid (HBI) alkenes for sea ice and TEX86L for temperature) and micropaleontological data (diatom assemblages), we derived new Holocene records of sea ice conditions and upper water column temperatures. The early Holocene (9000–7000 yr BP) was characterized by a cooling phase with a short sea ice season. During the mid-Holocene (~7000–3800 yr BP), local climate evolved towards slightly colder conditions and a prominent extension of the sea ice season occurred, promoting a favorable environment for intensive diatom growth. The late Holocene (the last ~2100 yr) was characterized by warmer temperatures and increased sea ice presence, accompanied by reduced local primary productivity, likely in response to a shorter growing season compared to the early or mid-Holocene. The gradual increase in annual sea ice duration over the last 7000 yr might have been influenced by decreasing mean annual and spring insolation, despite increasing summer insolation. We postulate that, in addition to precessional changes in insolation, seasonal variability, via changes in the strength of the circumpolar Westerlies and upwelling activity, was further amplified by the increasing frequency/amplitude of the El Niño–Southern Oscillation (ENSO). However, between 3800 and 2100 yr BP, the lack of correlation between ENSO and climate variability in the WAP suggests that other climatic factors might have been more important in controlling WAP climate at this time.

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Holocene climate variations in the western Antarctic Peninsula: evidence for sea ice extent predominantly controlled by insolation and ENSO variability changes

Climate of the Past Discussions ◽

10.5194/cpd-9-1-2013 ◽

2013 ◽

Vol 9 (1) ◽

pp. 1-41 ◽

Cited By ~ 3

Author(s):

J. Etourneau ◽

L. G. Collins ◽

V. Willmott ◽

J. H. Kim ◽

L. Barbara ◽

...

Keyword(s):

Sea Ice ◽

Water Column ◽

Antarctic Peninsula ◽

Primary Productivity ◽

Climatic Factors ◽

Southern Oscillation ◽

Western Antarctic Peninsula ◽

Deep Basin ◽

Sea Ice Extent ◽

Ice Conditions

Abstract. The West Antarctic ice sheet is particularly sensitive to global warming and its evolution and impact on global climate over the next few decades remains difficult to predict. In this context, investigating past sea ice conditions around Antarctica is of primary importance. Here, we document changes in sea ice presence, upper water column temperatures (0–200 m) and primary productivity over the last 9000 yr BP (before present) in the western Antarctic Peninsula (WAP) margin from a sedimentary core collected in the Palmer Deep basin. Employing a multi-proxy approach, we derived new Holocene records of sea ice conditions and upper water column temperatures, based on the combination of two biomarkers proxies (highly branched isoprenoid (HBI) alkenes for sea ice and TEXL86 for temperature) and micropaleontological data (diatom assemblages). The early Holocene (9000–7000 yr BP) was characterized by a cooling phase with a short sea ice season. During the mid-Holocene (~ 7000–3000 yr BP), local climate evolved towards slightly colder conditions and a prominent extension of the sea ice season occurred, promoting a favorable environment for intensive diatom growth. The late Holocene (the last ~ 3000 yr) was characterized by more variable temperatures and increased sea ice presence, accompanied by reduced local primary productivity likely in response to a shorter growing season compared to the early or mid-Holocene. The stepwise increase in annual sea ice duration over the last 7000 yr might have been influenced by decreasing mean annual and spring insolation despite an increasing summer insolation. We postulate that in addition to precessional changes in insolation, seasonal variability, via changes in the strength of the circumpolar Westerlies and upwelling activity, was further amplified by the increasing frequency/amplitude of El Niño-Southern Oscillation (ENSO). However, between 4000 and 2100 yr BP, the lack of correlation between ENSO and climate variability in the WAP suggests that other climatic factors might have been more important in controlling WAP climate at this time.

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Ice melt influence on summertime net community production along the Western Antarctic Peninsula

Deep Sea Research Part II Topical Studies in Oceanography ◽

10.1016/j.dsr2.2016.07.016 ◽

2017 ◽

Vol 139 ◽

pp. 89-102 ◽

Cited By ~ 20

Author(s):

R. Eveleth ◽

N. Cassar ◽

R.M. Sherrell ◽

H. Ducklow ◽

M.P. Meredith ◽

...

Keyword(s):

Antarctic Peninsula ◽

Western Antarctic Peninsula ◽

Net Community Production ◽

Ice Melt ◽

Community Production

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Climate Variability and Ecological Response of the Marine Ecosystem in the Western Antarctic Peninsula (WAP) Region

Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites ◽

10.1093/oso/9780195150599.003.0018 ◽

2003 ◽

Cited By ~ 1

Author(s):

Raymond C. Smith ◽

William R. Fraser

Keyword(s):

Sea Ice ◽

Air Temperature ◽

Antarctic Peninsula ◽

Marine Ecosystem ◽

Western Antarctic Peninsula ◽

Sea Ice Extent ◽

Half Century ◽

Air Temperatures ◽

Temperature Records ◽

The Antarctic

The Antarctic Peninsula, a relatively long, narrow extension of the Antarctic continent, defines a strong climatic gradient between the cold, dry continental regime to its south and the warm, moist maritime regime to its north. The potential for these contrasting climate regimes to shift in dominance from season to season and year to year creates a highly variable environment that is sensitive to climate perturbation. Consequently, long-term studies in the western Antarctic Peninsula (WAP) region, which is the location of the Palmer LTER (figure 9.1), provide the opportunity to observe how climate-driven variability in the physical environment is related to changes in the marine ecosystem (Ross et al. 1996; Smith et al. 1996; Smith et al. 1999). This is a sea ice–dominated ecosystem where the annual advance and retreat of the sea ice is a major physical determinant of spatial and temporal change in its structure and function, from total annual primary production to the breeding success and survival of seabirds. Mounting evidence suggests that the earth is experiencing a period of rapid climate change, and air temperature records from the last half century confirm a statistically significant warming trend within the WAP during the past half century (King 1994; King and Harangozo 1998; Marshall and King 1998; Ross et al. 1996; Sansom 1989; Smith et al. 1996; Stark 1994; van den Broeke 1998; Weatherly et al. 1991). Air temperature–sea ice linkages appear to be very strong in the WAP region (Jacka 1990; Jacka and Budd 1991; King 1994; Smith et al. 1996; Weatherly et al. 1991), and a statistically significant anticorrelation between air temperatures and sea ice extent has been observed for this region. Consistent with this strong coupling, sea ice extent in the WAP area has trended down during this period of satellite observations, and the sea ice season has shortened. In addition, both air temperature and sea ice have been shown to be significantly correlated with the Southern Oscillation Index (SOI), which suggests possible linkages among sea ice, cyclonic activity, and global teleconnections.

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Variations of surface air temperature and sea-ice extent in the western Antarctic Peninsula region

Annals of Glaciology ◽

10.3189/172756401781818662 ◽

2001 ◽

Vol 33 ◽

pp. 493-500 ◽

Cited By ~ 79

Author(s):

Raymond C. Smith ◽

Sharon E. Stammerjohn

Keyword(s):

Sea Ice ◽

Air Temperature ◽

Antarctic Peninsula ◽

Marine Ecosystem ◽

Surface Air Temperature ◽

Warming Trend ◽

Trophic Levels ◽

Western Antarctic Peninsula ◽

Sea Ice Extent ◽

The Past

AbstractThe western Antarctic Peninsula (WAP) region has experienced a statistically significant warming trend during the past half-century. In addition, a statistically significant anticorrelation between air temperatures and sea-ice extent, as determined from satellite passive-microwave data during the past two decades, has been observed for this region. Consistent with this strong coupling, sea-ice extent in the WAP area has trended down during this period of satellite observations. Further, much of the variability in both air temperature and sea ice in the WAP region has been shown to be influenced by contrasting maritime (warm, moist) and continental (cold, dry) climate regimes. As part of the Palmer Long Term Ecological Research program, the ecological influence of these trends and variability is being studied, and effects have already been demonstrated at all trophic levels. Here we extend earlier observations to include the past decade and focus on the annual cycles of air temperature and sea-ice extent for the past few years, with the aim of placing these recent observations within the context of changes seen in the longer-term records. The more recent years have seen an increasing maritime influence in the WAP region, with corresponding effects on the marine ecosystem.

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Climate change in the western Antarctic Peninsula since 1945: observations and possible causes

Annals of Glaciology ◽

10.3189/1998aog27-1-571-575 ◽

1998 ◽

Vol 27 ◽

pp. 571-575 ◽

Cited By ~ 115

Author(s):

J. C. King ◽

S. A. Harangozo

Keyword(s):

Sea Ice ◽

Atmospheric Circulation ◽

Antarctic Peninsula ◽

The West ◽

Sea Ice Extent ◽

The North ◽

Ultimate Cause ◽

Temperature Records ◽

High Level ◽

The Antarctic

Temperature records from slations on the west roast of the Antarctic Peninsula show a very high level of interannual variability and, over the last 50 years, larger warming trends than are seen elsewhere in Antarctica. in this paper we investigate the role of atmospheric circulation variability and sea-ice extent variations in driving these changes. Owing to a lack of independent data, the reliability of Antarctic atmospheric analyses produced in the 1950s and 1960s cannot be readily established, but examination of the available data suggests that there has been an increase in the northerly component of the circulation over the Peninsula since the late 1950s. Few observations of sea-ice extent are available prior to 1973, but the limited data available indicate that the ice edge to the west of the Peninsula lay to the north of recently observed extremes during the very cold conditions prevailing in the late 1950s. The ultimate cause of the atmospheric-circulation changes remains to be determined and may lie outside the Antarctic region.

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