Distribution of dinocyst assemblages in surface sediment samples from the West Greenland margin

Allan, Estelle; Vernal, Anne de; Krawczyk, Diana; Moros, Matthias; Radi, Taoufik; Rochon, André; Seidenkrantz, Marit‐Solveig; Zaragosi, Sébastien

doi:10.1016/j.marmicro.2019.101818

Cited by 7 publications

(17 citation statements)

References 41 publications

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“…(Fig. 4), suggests the recurrence of cold conditions (Allan et al 2020), which probably led to generally low summer SST and high SSS, similar to the present-day (Fig. 6).…”

Section: Hydrographic Conditions During the Holocenesupporting

confidence: 62%

“…In addition, most studies documenting the distribution of dinocysts on the sea floor indicate regionalism of assemblages and limited impact of distal inputs. Analyses of surface sediments from the southwest Greenland margin show strong gradients in the dinocyst taxa distribution (Allan et al 2020), suggesting clear boundaries linked to proximal fluxes.…”

Section: Discussionmentioning

confidence: 99%

“…4) likely relate to an increase of productivity and light availability. The cysts of Pentapharsodinium dalei are often found in stratified waters and may be linked to low salinity related to freshwater meltwater input together with primary productivity (Rochon et al 1999;Heikkilä et al 2014;Allan et al 2020). Its dominance, from 10 to 3 ka BP (Fig.…”

Section: Palynological Contentmentioning

confidence: 99%

“…4), could be related to the late summer bloom due to meltwater input (e.g. Boertmann et al 2013;Juul-Pedersen et al 2015;Allan et al 2020), while its subsequent decline, relative to heterotrophic taxa such as Islandinium minutum, Islandinium? cezare and Brigantedinium spp.…”

Section: Palynological Contentmentioning

confidence: 99%

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Insolation vs. meltwater control of productivity and sea surface conditions off SW Greenland during the Holocene

Allan

Vernal

Seidenkrantz

et al. 2021

Boreas

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We address here the specific timing and amplitude of sea-surface conditions and productivity changes off SW Greenland, northern Labrador Sea, in response to the high deglacial meltwater rates, the Early Holocene maximum insolation and Neoglacial cooling. Dinocyst assemblages from sediment cores collected off Nuuk were used to set up quantitative records of sea ice cover, seasonal sea-surface temperature (SST), salinity (SSS), and primary productivity, with a centennial to millennial scale resolution. Until~10 ka BP, ice-proximal conditions are suggested by the quasi-exclusive dominance of heterotrophic taxa and low dinocyst concentrations. At about 10 ka BP, an increase in species diversity and abundance of phototrophic taxa marks the onset of interglacial conditions at a regional scale, with summer SST reaching up to 10°C between 8 and 5 ka BP, thus in phase with the Holocene Thermal Maximum as recorded in the southern Greenlandic areas/northern Labrador Sea. During this interval, low SSS but high productivity prevailed in response to high meltwater discharge and nutrient inputs from the Greenland Ice Sheet. After~5 ka BP, a decrease in phototrophic taxa marks a two-step cooling of surface waters. The first started at~5 ka BP, and the second at~3 ka BP, with a shift toward colder conditions and higher SSS suggesting reduced meltwater discharge during the Neoglacial. This second step coincides with the disappearance of the Saqqaq culture. The gap in human occupation in west Greenland, between the Dorset and the Norse settlements from 2000 to 1000 years BP, might be linked to high amplitude and high frequency variability of ocean and climate conditions.

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“…(Fig. 4), suggests the recurrence of cold conditions (Allan et al 2020), which probably led to generally low summer SST and high SSS, similar to the present-day (Fig. 6).…”

Section: Hydrographic Conditions During the Holocenesupporting

confidence: 62%

Section: Discussionmentioning

confidence: 99%

Section: Palynological Contentmentioning

confidence: 99%

Section: Palynological Contentmentioning

confidence: 99%

See 2 more Smart Citations

Insolation vs. meltwater control of productivity and sea surface conditions off SW Greenland during the Holocene

Allan

Vernal

Seidenkrantz

et al. 2021

Boreas

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“…Surface sediment (0–2 cm interval) samples recovered from the study area may represent several decades to centuries of accumulation, depending on sedimentation rates and vertical mixing by bioturbation. As several studies already addressed this issue (Allan et al., 2020; Kolling et al., 2020; Krawczyk et al., 2017, 2021), the following discussion will avoid comparing single sites and focus on general patterns.…”

Section: Discussionmentioning

confidence: 99%

Palmitic Acid Is Not a Proper Salinity Proxy in Baffin Bay and the Labrador Sea but Reflects the Variability in Organic Matter Sources Modulated by Sea Ice Coverage

Allan,

Douglas,

de Vernal

et al. 2023

Geochem Geophys Geosyst

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Palmitic acid (PA) is ubiquitous in the biosphere and its hydrogen isotopic composition (δ2HPA) was proposed as a potential paleoenvironmental proxy for salinity, with δ2HPA values increasing with salinity. In this study, we analyzed 40 surface sediment samples from Baffin Bay and the Labrador Sea to examine the isotopic composition of PA in relation to local environmental variables, including salinity. In contrast to expectations, our results show a negative relationship between the δ2HPA and sea‐surface salinity, raising questions about its pertinence and usefulness as a salinity proxy. Instead, our results suggest that the relative abundance of distinct organisms that employ different metabolisms is the key in determining the hydrogen isotopic fractionations in PA. While we show that PA is mostly produced through photoautotrophic metabolisms by diatoms and dinoflagellates, varying contributions from heterotrophic metabolisms may obscure the stable isotope composition of PA. Surprisingly, we found no correlation between the stable carbon isotopic composition of the sedimentary organic matter (δ13Corg) and PA (δ13CPA), implying major differences in either the dominant organisms producing sedimentary PA or in carbon isotope fractionation during lipid biosynthesis. We also found that the presence of extended sea‐ice cover leads to enriched carbon and hydrogen isotopic compositions in PA. These enriched values suggest heterotrophic biodegradation in the water column and/or in the sediment as well as an increase in grazing activities. We propose that sea‐ice cover and surface water oxygenation modulate the relative impact of phototrophic and heterotrophic metabolisms, and therefore the isotopic composition of marine sedimentary PA.

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A historical perspective on the development of the Northern Hemisphere modern dinoflagellate cyst database

Nieuwenhove

Pospelova

Vernal

et al. 2020

Marine Micropaleontology

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Distribution of dinocyst assemblages in surface sediment samples from the West Greenland margin

Cited by 7 publications

References 41 publications

Insolation vs. meltwater control of productivity and sea surface conditions off SW Greenland during the Holocene

Insolation vs. meltwater control of productivity and sea surface conditions off SW Greenland during the Holocene

Palmitic Acid Is Not a Proper Salinity Proxy in Baffin Bay and the Labrador Sea but Reflects the Variability in Organic Matter Sources Modulated by Sea Ice Coverage

A historical perspective on the development of the Northern Hemisphere modern dinoflagellate cyst database

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