scholarly journals Decadal trend of plankton community change and habitat shoaling in the Arctic gateway recorded by planktonic foraminifera

2021 ◽  
Author(s):  
Mattia Greco ◽  
Kirstin Werner ◽  
Katarzyna Zamelczyk ◽  
Tine L. Rasmussen ◽  
Michal Kucera
Keyword(s):  
Planktonic Foraminifera ◽  
Community Change ◽  
Plankton Community ◽  
The Arctic ◽  
Decadal Trend

scholarly journals Decadal trend of plankton community change and habitat shoaling in the Arctic gateway recorded by planktonic foraminifera

2021 ◽  
Author(s):  
Mattia Greco ◽  
Kirstin Werner ◽  
Katarzyna Zamelczyk ◽  
Tine L. Rasmussen ◽  
Michal Kucera
Keyword(s):  
Sea Ice ◽  
Planktonic Foraminifera ◽  
Community Change ◽  
Plankton Community ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Fram Strait ◽  
Resident Species ◽  
Ice Dynamics ◽  
Pelagic Community

AbstractThe Fram Strait plays a crucial role in regulating the heat and sea-ice dynamics in the Arctic. In response to the ongoing global warming, the marine biota of this Arctic gateway is experiencing significant changes with increasing advection of Atlantic species. The footprint of this “Atlantification” has been identified in isolated observations across the plankton community, but a systematic, multi-decadal perspective on how regional climate change facilitates the invasion of Atlantic species and affects the ecology of the resident species is lacking. Here we evaluate a series of 51 depth-resolved plankton profiles collected in the Fram Strait during seven surveys between 1985 and 2015, using planktonic foraminifera as a proxy for changes in both the pelagic community composition and species vertical habitat depth. The time series reveals a progressive shift towards more Atlantic species, occurring independently of changes in local environmental conditions. We conclude that this trend is reflecting higher production of the Atlantic species in the “source” region, from where they are advected into the Fram Strait. At the same time, we observe that the ongoing extensive sea-ice export from the Arctic and associated cooling-induced decline in density and habitat shoaling of the subpolar Turborotalita quinqueloba, whereas the resident Neogloboquadrina pachyderma persists. As a result, the planktonic foraminiferal community and vertical structure in the Fram Strait shifts to a new state, driven by both remote forcing of the Atlantic invaders and local climatic changes acting on the resident species. The strong summer export of Arctic sea ice has so far buffered larger plankton transformation. We predict that if the sea-ice export will decrease, the Arctic gateway will experience rapid restructuring of the pelagic community, even in the absence of further warming. Such a large change in the gateway region will likely propagate into the Arctic proper.

scholarly journals Planktonic foraminifera genomic variations reflect paleoceanographic changes in the Arctic: evidence from sedimentary ancient DNA

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Joanna Pawłowska ◽  
Jutta E. Wollenburg ◽  
Marek Zajączkowski ◽  
Jan Pawlowski
Keyword(s):  
Ancient Dna ◽  
Sequence Data ◽  
Planktonic Foraminifera ◽  
Molecular Ecology ◽  
The Arctic ◽  
Marine Biodiversity ◽  
Neogloboquadrina Pachyderma ◽  
Rna Genes ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract Deciphering the evolution of marine plankton is typically based on the study of microfossil groups. Cryptic speciation is common in these groups, and large intragenomic variations occur in ribosomal RNA genes of many morphospecies. In this study, we correlated the distribution of ribosomal amplicon sequence variants (ASVs) with paleoceanographic changes by analyzing the high-throughput sequence data assigned to Neogloboquadrina pachyderma in a 140,000-year-old sediment core from the Arctic Ocean. The sedimentary ancient DNA demonstrated the occurrence of various N. pachyderma ASVs whose occurrence and dominance varied through time. Most remarkable was the striking appearance of ASV18, which was nearly absent in older sediments but became dominant during the last glacial maximum and continues to persist today. Although the molecular ecology of planktonic foraminifera is still poorly known, the analysis of their intragenomic variations through time has the potential to provide new insight into the evolution of marine biodiversity and may lead to the development of new and important paleoceanographic proxies.

scholarly journals Carbon isotope (δ<sup>13</sup>C) excursions suggest times of major methane release during the last 14 kyr in Fram Strait, the deep-water gateway to the Arctic

2015 ◽  
Vol 11 (4) ◽  
pp. 669-685 ◽  
Author(s):  
C. Consolaro ◽  
T. L. Rasmussen ◽  
G. Panieri ◽  
J. Mienert ◽  
S. Bünz ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Carbon Isotope ◽  
Deep Water ◽  
Planktonic Foraminifera ◽  
Sediment Supply ◽  
The Arctic ◽  
Fram Strait ◽  
The North ◽  
Carbon Isotope Excursion

Abstract. We present results from a sediment core collected from a pockmark field on the Vestnesa Ridge (~ 80° N) in the eastern Fram Strait. This is the only deep-water gateway to the Arctic, and one of the northernmost marine gas hydrate provinces in the world. Eight 14C AMS dates reveal a detailed chronology for the last 14 ka BP. The δ 13C record measured on the benthonic foraminiferal species Cassidulina neoteretis shows two distinct intervals with negative values termed carbon isotope excursion (CIE I and CIE II, respectively). The values were as low as −4.37‰ in CIE I, correlating with the Bølling–Allerød interstadials, and as low as −3.41‰ in CIE II, correlating with the early Holocene. In the Bølling–Allerød interstadials, the planktonic foraminifera also show negative values, probably indicating secondary methane-derived authigenic precipitation affecting the foraminiferal shells. After a cleaning procedure designed to remove authigenic carbonate coatings on benthonic foraminiferal tests from this event, the 13C values are still negative (as low as −2.75‰). The CIE I and CIE II occurred during periods of ocean warming, sea-level rise and increased concentrations of methane (CH4) in the atmosphere. CIEs with similar timing have been reported from other areas in the North Atlantic, suggesting a regional event. The trigger mechanisms for such regional events remain to be determined. We speculate that sea-level rise and seabed loading due to high sediment supply in combination with increased seismic activity as a result of rapid deglaciation may have triggered the escape of significant amounts of methane to the seafloor and the water column above.

Early to mid-Holocene Atlantic water influx and deglacial meltwater events, Beaufort Sea Slope, Arctic Ocean

2004 ◽  
Vol 61 (1) ◽  
pp. 14-21 ◽  
Author(s):  
John T. Andrews ◽  
Gita Dunhill
Keyword(s):  
Arctic Ocean ◽  
Planktonic Foraminifera ◽  
Sediment Accumulation ◽  
Beaufort Sea ◽  
Atlantic Water ◽  
The Arctic ◽  
Silty Clay ◽  
Cold Event ◽  
Radiocarbon Dates ◽  
Average Grain Size

Holocene high-resolution cores from the margin of the Arctic Ocean are rare. Core P189AR-P45 collected in 405-m water depth on the Beaufort Sea slope, west of the Mackenzie River delta (70°33.03′N and 141°52.08′W), is in close vertical proximity to the present-day upper limit of modified Atlantic water. The 5.11-m core spans the interval between ∼6800 and 10,400 14C yr B.P. (with an 800-yr ocean reservoir correction). The sediment is primarily silty clay with an average grain-size of 9 φ. The chronology is constrained by seven radiocarbon dates. The rate of sediment accumulation averaged 1.35 mm/yr. Stable isotopic data (δ18O and δ13C) were obtained on the polar planktonic foraminifera Neogloboquadrina pachyderma (s) and the benthic infaunal species Cassidulina neoteretis. A distinct low-δ18O event is captured in both the benthic and planktonic data at ∼10,000 14C yr B.P.—probably recording the glacial Lake Agassiz outburst flood associated with the North Atlantic preboreal cold event. The benthic foraminifera are dominated in the earliest Holocene by C. neoteretis, a species associated with modified Atlantic water masses. This species decreases toward the core top with a marked environmental reversal occurring ∼7800 14C yr B.P. possibly coincident with the northern hemisphere 8200 cal yr B.P. cold event.

scholarly journals Effect of ocean acidification on the fatty acid composition of a natural plankton community

2013 ◽  
Vol 10 (2) ◽  
pp. 1143-1153 ◽  
Author(s):  
E. Leu ◽  
M. Daase ◽  
K. G. Schulz ◽  
A. Stuhr ◽  
U. Riebesell
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Ocean Acidification ◽  
Acid Composition ◽  
Essential Fatty Acids ◽  
Plankton Community ◽  
Nutrient Addition ◽  
Inorganic Nutrients ◽  
The Arctic

Abstract. The effect of ocean acidification on the fatty acid composition of a natural plankton community in the Arctic was studied in a large-scale mesocosm experiment, carried out in Kongsfjorden (Svalbard, Norway) at 79° N. Nine mesocosms of ~50 m3 each were exposed to 8 different pCO2 levels (from natural background conditions to ~1420 μatm), yielding pH values (on the total scale) from ~8.3 to 7.5. Inorganic nutrients were added on day 13. The phytoplankton development during this 30-day experiment passed three distinct phases: (1) prior to the addition of inorganic nutrients, (2) first bloom after nutrient addition, and (3) second bloom after nutrient addition. The fatty acid composition of the natural plankton community was analysed and showed, in general, high percentages of polyunsaturated fatty acids (PUFAs): 44–60% of total fatty acids. Positive correlations with pCO2 were found for most PUFAs during phases 2 and/or 3, with the exception of 20:5n3 (eicosapentaenoic acid, EPA), an important diatom marker. These correlations are probably linked to changes in taxonomic composition in response to pCO2. While diatoms (together with prasinophytes and haptophytes) increased during phase 3 mainly in the low and intermediate pCO2 treatments, dinoflagellates were favoured by high CO2 concentrations during the same time period. This is reflected in the development of group-specific fatty acid trophic markers. No indications were found for a generally detrimental effect of ocean acidification on the planktonic food quality in terms of essential fatty acids.

scholarly journals Response of halocarbons to ocean acidification in the Arctic

2013 ◽  
Vol 10 (4) ◽  
pp. 2331-2345 ◽  
Author(s):  
F. E. Hopkins ◽  
S. A. Kimmance ◽  
J. A. Stephens ◽  
R. G. J. Bellerby ◽  
C. P. D. Brussaard ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Temporal Dynamics ◽  
Strong Association ◽  
Potential Effect ◽  
Plankton Community ◽  
The Arctic ◽  
Biological Parameters ◽  
Biological Source ◽  
Phytoplankton Communities ◽  
June July

Abstract. The potential effect of ocean acidification (OA) on seawater halocarbons in the Arctic was investigated during a mesocosm experiment in Spitsbergen in June–July 2010. Over a period of 5 weeks, natural phytoplankton communities in nine ~ 50 m3 mesocosms were studied under a range of pCO2 treatments from ~ 185 μatm to ~ 1420 μatm. In general, the response of halocarbons to pCO2 was subtle, or undetectable. A large number of significant correlations with a range of biological parameters (chlorophyll a, microbial plankton community, phytoplankton pigments) were identified, indicating a biological control on the concentrations of halocarbons within the mesocosms. The temporal dynamics of iodomethane (CH3I) alluded to active turnover of this halocarbon in the mesocosms and strong significant correlations with biological parameters suggested a biological source. However, despite a pCO2 effect on various components of the plankton community, and a strong association between CH3I and biological parameters, no effect of pCO2 was seen in CH3I. Diiodomethane (CH2I2) displayed a number of strong relationships with biological parameters. Furthermore, the concentrations, the rate of net production and the sea-to-air flux of CH2I2 showed a significant positive response to pCO2. There was no clear effect of pCO2 on bromocarbon concentrations or dynamics. However, periods of significant net loss of bromoform (CHBr3) were found to be concentration-dependent, and closely correlated with total bacteria, suggesting a degree of biological consumption of this halocarbon in Arctic waters. Although the effects of OA on halocarbon concentrations were marginal, this study provides invaluable information on the production and cycling of halocarbons in a region of the world's oceans likely to experience rapid environmental change in the coming decades.

scholarly journals Depth habitat of the planktonic foraminifera <i>Neogloboquadrina pachyderma</i> in the northern high latitudes explained by sea-ice and chlorophyll concentrations

2019 ◽  
Vol 16 (17) ◽  
pp. 3425-3437 ◽  
Author(s):  
Mattia Greco ◽  
Lukas Jonkers ◽  
Kerstin Kretschmer ◽  
Jelle Bijma ◽  
Michal Kucera
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Chlorophyll A ◽  
Mixed Layer ◽  
Planktonic Foraminifera ◽  
Sea Surface ◽  
The Arctic ◽  
Polar Regions ◽  
Neogloboquadrina Pachyderma ◽  
Chlorophyll Concentrations

Abstract. Neogloboquadrina pachyderma is the dominant planktonic foraminifera species in the polar regions. In the northern high-latitude ocean, it makes up more than 90 % of the total assemblages, making it the dominant pelagic calcifier and carrier of paleoceanographic proxies. To assess the reaction of this species to a future shaped by climate change and to be able to interpret the paleoecological signal contained in its shells, its depth habitat must be known. Previous work showed that N. pachyderma in the northern polar regions has a highly variable depth habitat, ranging from the surface mixed layer to several hundreds of metres below the surface, and the origin of this variability remained unclear. In order to investigate the factors controlling the depth habitat of N. pachyderma, we compiled new and existing population density profiles from 104 stratified plankton tow hauls collected in the Arctic and the North Atlantic oceans during 14 oceanographic expeditions. For each vertical profile, the depth habitat (DH) was calculated as the abundance-weighted mean depth of occurrence. We then tested to what degree environmental factors (mixed-layer depth, sea surface temperature, sea surface salinity, chlorophyll a concentration, and sea ice concentration) and ecological factors (synchronized reproduction and daily vertical migration) can predict the observed DH variability and compared the observed DH behaviour with simulations by a numerical model predicting planktonic foraminifera distribution. Our data show that the DH of N. pachyderma varies between 25 and 280 m (average ∼100 m). In contrast with the model simulations, which indicate that DH is associated with the depth of chlorophyll maximum, our analysis indicates that the presence of sea ice together with the concentration of chlorophyll a at the surface have the strongest influence on the vertical habitat of this species. N. pachyderma occurs deeper when sea ice and chlorophyll concentrations are low, suggesting a time-transgressive response to the evolution of (near) surface conditions during the annual cycle. Since only surface parameters appear to affect the vertical habitat of N. pachyderma, light or light-dependant processes might influence the ecology of this species. Our results can be used to improve predictions of the response of the species to climate change and thus to refine paleoclimatic reconstructions.

scholarly journals Effect of ocean acidification on the fatty acid composition of a natural plankton community

2012 ◽  
Vol 9 (7) ◽  
pp. 8173-8197 ◽  
Author(s):  
E. Leu ◽  
M. Daase ◽  
K. G. Schulz ◽  
A. Stuhr ◽  
U. Riebesell
Keyword(s):  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Ocean Acidification ◽  
Acid Composition ◽  
Plankton Community ◽  
Nutrient Addition ◽  
Inorganic Nutrients ◽  
The Arctic ◽  
Positive Correlations

Abstract. The effect of ocean acidification on the fatty acid composition of a natural plankton community in the Arctic was studied in a large-scale mesocosm experiment, carried out in Kongsfjorden (Svalbard, Norway) at 79° N. Nine mesocosms of ~50 cbm each were exposed to different pCO2 levels (from natural background conditions to ~1420 μatm), yielding pH values (on the total scale) from ~8.3 to 7.5. Inorganic nutrients were added on day 13. The phytoplankton development during this 30 days experiment passed three distinct phases: (1) prior to the addition of inorganic nutrients, (2) first bloom after nutrient addition, and (3) second bloom after nutrient addition. The fatty acid composition of the natural plankton community was analysed and showed, in general, high percentages of polyunsaturated fatty acids (PUFAs): 44–60% of total fatty acids. Positive correlations with pCO2 were found for most PUFAs during phases 2 and/or 3, with the exception of 20:5n3 (eicosapentaenoic acid, EPA), an important diatom marker. There are strong indications for these correlations being mediated indirectly through taxonomic changes and the natural development of the communities in the mesocosms exposed to different pCO2 levels. While diatoms increased during phase 3 mainly in the low and intermediate pCO2 treatments, dinoflagellates were favoured by high CO2 concentrations during the same time period. This is reflected in the development of group-specific fatty acid trophic markers. No indications were found for a generally detrimental effect of ocean acidification on the planktonic food quality in terms of essential fatty acids. The significant positive correlations between most PUFAs and pCO2 reflected treatment-dependent differences in the community composition between the mesocosms rather than a direct positive effect of pCO2 on specific fatty acids.

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