scholarly journals Influence of environmental variability and Emiliania huxleyi ecotypes on alkenone-derived temperature reconstructions in the subantarctic Southern Ocean

2021 ◽  
pp. 152474
Author(s):  
A.S. Rigual-Hernández ◽  
F.J. Sierro ◽  
J.A. Flores ◽  
T.W. Trull ◽  
T. Rodrigues ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Environmental Variability ◽  
Emiliania Huxleyi ◽  
Temperature Reconstructions

scholarly journals Calcification morphotypes of the coccolithophorid Emiliania huxleyi in the Southern Ocean: changes in 2001 to 2006 compared to historical data

2007 ◽  
Vol 348 ◽  
pp. 47-54 ◽  
Author(s):  
JC Cubillos ◽  
SW Wright ◽  
G Nash ◽  
MF de Salas ◽  
B Griffiths ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Historical Data ◽  
Emiliania Huxleyi

scholarly journals Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

2016 ◽  
Vol 13 (16) ◽  
pp. 4843-4861 ◽  
Author(s):  
Xiaobo Jin ◽  
Chuanlian Liu ◽  
Alex J. Poulton ◽  
Minhan Dai ◽  
Xianghui Guo
Keyword(s):  
South China Sea ◽  
Species Composition ◽  
Water Column ◽  
South China ◽  
Water Samples ◽  
Environmental Variability ◽  
Emiliania Huxleyi ◽  
The South China Sea ◽  
The South ◽  
China Sea

Abstract. Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths) and the relative cellular levels of photosynthesis and calcification rates. All three of these factors vary between coccolithophore species and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. Average coccolithophore abundance and their calcite concentration in the water column were 11.82 cells mL−1 and 1508.3 pg C mL−1, respectively, during the cruise. Water samples can be divided into three floral groups according to their distinct coccolithophore communities. The vertical structure of the coccolithophore community in the water column was controlled by the trophic conditions, which were regulated by mesoscale eddies across the SCS basin. The evaluation of coccolithophore-based calcite in the surface ocean also showed that three key species in the SCS (Emiliania huxleyi, Gephyrocapsa oceanica, Florisphaera profunda) and other larger, numerically rare species made almost equal contributions to total coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients (nitrate, phosphate), and it is suggested that coccolith length is influenced by light and nutrients through the regulation of growth rates. Larger-sized coccoliths were also linked statistically to low pH and calcite saturation states; however, it is not a simple cause and effect relationship, as carbonate chemistry was strongly co-correlated with the other key environmental factors (nutrients, light).

scholarly journals Population-specific responses in physiological rates of <i>Emiliania huxleyi</i> to a broad CO<sub>2</sub> range

2018 ◽  
Vol 15 (12) ◽  
pp. 3691-3701 ◽  
Author(s):  
Yong Zhang ◽  
Lennart T. Bach ◽  
Kai T. Lohbeck ◽  
Kai G. Schulz ◽  
Luisa Listmann ◽  
...  
Keyword(s):  
Canary Islands ◽  
Environmental Variability ◽  
Incubation Temperature ◽  
North Atlantic Ocean ◽  
Physiological Responses ◽  
Maximum Growth ◽  
Emiliania Huxleyi ◽  
Production Rates ◽  
Co2 Partial Pressure ◽  
Norwegian Coast

Abstract. Although coccolithophore physiological responses to CO2-induced changes in seawater carbonate chemistry have been widely studied in the past, there is limited knowledge on the variability of physiological responses between populations from different areas. In the present study, we investigated the specific responses of growth, particulate organic (POC) and inorganic carbon (PIC) production rates of three populations of the coccolithophore Emiliania huxleyi from three regions in the North Atlantic Ocean (Azores: six strains, Canary Islands: five strains, and Norwegian coast near Bergen: six strains) to a CO2 partial pressure (pCO2) range from 120 to 2630 µatm. Physiological rates of each population and individual strain increased with rising pCO2 levels, reached a maximum and declined thereafter. Optimal pCO2 for growth, POC production rates, and tolerance to low pH (i.e., high proton concentration) was significantly higher in an E. huxleyi population isolated from the Norwegian coast than in those isolated near the Azores and Canary Islands. This may be due to the large environmental variability including large pCO2 and pH fluctuations in coastal waters off Bergen compared to the rather stable oceanic conditions at the other two sites. Maximum growth and POC production rates of the Azores and Bergen populations were similar and significantly higher than that of the Canary Islands population. This pattern could be driven by temperature–CO2 interactions where the chosen incubation temperature (16 ∘C) was slightly below what strains isolated near the Canary Islands normally experience. Our results indicate adaptation of E. huxleyi to their local environmental conditions and the existence of distinct E. huxleyi populations. Within each population, different growth, POC, and PIC production rates at different pCO2 levels indicated strain-specific phenotypic plasticity. Accounting for this variability is important to understand how or whether E. huxleyi might adapt to rising CO2 levels.

Revised Southern Ocean sea surface temperatures over the last 180 ka

2021 ◽  
Author(s):  
David Chandler ◽  
Petra Langebroek
Keyword(s):  
Southern Ocean ◽  
Sea Level ◽  
Climate Model ◽  
Ice Sheet ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Last Interglacial ◽  
Antarctic Ice Sheet ◽  
Surface Temperatures ◽  
Temperature Reconstructions

&lt;p&gt;Proxy records and climate models suggest that the Last Interglacial (LIG, ~130 to 115 thousand years before present) was characterised by high-latitude air and sea surface temperatures (SSTs) slightly warmer than present, and by mean global sea level a few metres higher. Therefore, the LIG is widely used as an analogue for near-future oceanographic/climatic conditions. Of particular interest is the Antarctic Ice Sheet&amp;#8217;s contribution to rapid sea level rise and to Southern Ocean surface freshening, in response to warming. In the Southern Ocean, existing LIG temperature reconstructions suffer from very high variance amongst a low number of individual records. Recent syntheses have focused on the LIG climatic optimum, but conditions during the penultimate glacial are also important for forcing transient climate or Antarctic Ice Sheet simulations. Here we use databases of modern core-top sediments to evaluate the strengths of SST proxies available in the Southern Ocean, and consider their likely sources of bias and variance. By selecting only those paleo-temperature reconstructions which we believe are reliable in this region, we then compile a Southern Ocean SST synthesis covering the penultimate glacial and the LIG. This longer temperature time series can be used as a basis for LIG ice sheet simulations or for climate model development.&amp;#160;&amp;#160;&lt;/p&gt;

scholarly journals The influence of environmental variability on the biogeography of coccolithophores and diatoms in the Great Calcite Belt

2017 ◽  
Vol 14 (21) ◽  
pp. 4905-4925 ◽  
Author(s):  
Helen E. K. Smith ◽  
Alex J. Poulton ◽  
Rebecca Garley ◽  
Jason Hopkins ◽  
Laura C. Lubelczyk ◽  
...  
Keyword(s):  
Species Composition ◽  
Southern Ocean ◽  
Silicic Acid ◽  
Mixed Layer ◽  
Dissolved Inorganic Carbon ◽  
Emiliania Huxleyi ◽  
The South ◽  
Carbonate Chemistry ◽  
Atlantic Sector ◽  
South Indian

Abstract. The Great Calcite Belt (GCB) of the Southern Ocean is a region of elevated summertime upper ocean calcite concentration derived from coccolithophores, despite the region being known for its diatom predominance. The overlap of two major phytoplankton groups, coccolithophores and diatoms, in the dynamic frontal systems characteristic of this region provides an ideal setting to study environmental influences on the distribution of different species within these taxonomic groups. Samples for phytoplankton enumeration were collected from the upper mixed layer (30 m) during two cruises, the first to the South Atlantic sector (January–February 2011; 60° W–15° E and 36–60° S) and the second in the South Indian sector (February–March 2012; 40–120° E and 36–60° S). The species composition of coccolithophores and diatoms was examined using scanning electron microscopy at 27 stations across the Subtropical, Polar, and Subantarctic fronts. The influence of environmental parameters, such as sea surface temperature (SST), salinity, carbonate chemistry (pH, partial pressure of CO2 (pCO2), alkalinity, dissolved inorganic carbon), macronutrients (nitrate + nitrite, phosphate, silicic acid, ammonia), and mixed layer average irradiance, on species composition across the GCB was assessed statistically. Nanophytoplankton (cells 2–20 µm) were the numerically abundant size group of biomineralizing phytoplankton across the GCB, with the coccolithophore Emiliania huxleyi and diatoms Fragilariopsis nana, F. pseudonana, and Pseudo-nitzschia spp. as the most numerically dominant and widely distributed. A combination of SST, macronutrient concentrations, and pCO2 provided the best statistical descriptors of the biogeographic variability in biomineralizing species composition between stations. Emiliania huxleyi occurred in silicic acid-depleted waters between the Subantarctic Front and the Polar Front, a favorable environment for this species after spring diatom blooms remove silicic acid. Multivariate statistics identified a combination of carbonate chemistry and macronutrients, covarying with temperature, as the dominant drivers of biomineralizing nanoplankton in the GCB sector of the Southern Ocean.

scholarly journals Limited variability in the phytoplankton Emiliania huxleyi since the pre-industrial era in the Subantarctic Southern Ocean

Anthropocene ◽  
2020 ◽  
Vol 31 ◽  
pp. 100254
Author(s):  
A.S. Rigual-Hernández ◽  
J.M. Sánchez-Santos ◽  
R. Eriksen ◽  
A.D. Moy ◽  
F.J. Sierro ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Emiliania Huxleyi

PHOTOSYNTHETIC PIGMENT AND GENETIC DIFFERENCES BETWEEN TWO SOUTHERN OCEAN MORPHOTYPES OF EMILIANIA HUXLEYI (HAPTOPHYTA)1

2011 ◽  
Vol 47 (3) ◽  
pp. 615-626 ◽  
Author(s):  
Suellen S. Cook ◽  
Lucy Whittock ◽  
Simon W. Wright ◽  
Gustaaf M. Hallegraeff
Keyword(s):  
Southern Ocean ◽  
Photosynthetic Pigment ◽  
Emiliania Huxleyi ◽  
Genetic Differences

Has (anthropogenic) climate change driven subantarctic Emiliania huxleyi populations beyond their natural state?

2021 ◽  
Author(s):  
Andres S. Rigual-Hernandez ◽  
Francisco J. Sierro ◽  
José A. Flores ◽  
José M. Sánchez-Santos ◽  
Ruth S. Eriksen ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Environmental Change ◽  
Ocean Acidification ◽  
Emiliania Huxleyi ◽  
Global Ocean ◽  
Natural State ◽  
Sedimentary Record ◽  
Subtle Change ◽  
Assemblage Composition ◽  
Biogeographical Distribution

&lt;p&gt;The global ocean acts as a climate regulator through the uptake of Earth&amp;#8217;s excess heat and the absorption of about 30% of anthropogenic CO&lt;sub&gt;2&lt;/sub&gt; emissions since 1750. &amp;#160;Southern Ocean waters are warming faster than the global ocean average and their low temperatures and moderate alkalinity make this region especially vulnerable to ocean acidification. Coccolithophores are a major group of calcifying phytoplankton and an important component of the Southern Ocean carbon cycle. Controlled laboratory experiments on &lt;em&gt;Emiliania huxleyi &lt;/em&gt;(the most abundant coccolithophore) over a broad range of carbonate chemistry scenarios suggest that this taxon may be susceptible to ongoing environmental change. However, it remains uncertain whether Southern Ocean coccolithophore populations have been modified by environmental change during the industrial era. The main reason for this knowledge gap is the lack of observational data since the onset of the Industrial Revolution. In particular, continuous monitoring of key Southern Ocean ecosystems only started a few decades ago, a period insufficiently long to permit assessments of whether anthropogenic impacts on the environment have affected coccolithophore populations beyond their natural state. In order to overcome this limitation, here we take advantage of the preservation capacity of coccolithophores in the sedimentary record to provide a benchmark of their pre-industrial state. We compare the morphotype assemblage composition and morphometric parameters in coccoliths of &lt;em&gt;E. huxleyi &lt;/em&gt;from a suite of Holocene-aged sediments south of Tasmania with annual sediment trap records retrieved at the Southern Ocean Time Series observatory in the Australian sector of the Subantarctic Zone. Our results suggest that carbonate dissolution in the sediments reduced the coccolith mass and length of the coccoliths but, coccolith thickness appeared to be decoupled from dissolution. The biogeographical distribution of coccolith thickness in subtropical and subantarctic sediments mirrored the distribution of E. huxleyi morphotypes, highlighting the important role of &lt;em&gt;E. huxleyi &lt;/em&gt;assemblage composition on the control of coccolith morphometrics. Moreover, comparison of coccolith assemblages from the sedimentary record with those collected from subantarctic sediment traps indicates that modern E. huxleyi coccoliths are about 2% thinner than those from the pre-industrial Holocene. The subtle change in coccolith thickness is in stark contrast with previous work that documented a dramatic reduction in shell calcification in the planktonic foraminifera &lt;em&gt;Globigerina bulloides &lt;/em&gt;that resulted in a shell-weight decrease of 30-35%, most likely induced by ocean acidification. Overall, our results underscore the variable sensitivity of different marine calcifying plankton groups to ongoing environmental change in the Southern Ocean.&lt;/p&gt;

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