Variable response of North Atlantic deep-sea benthic ecosystems to industrial-era climate change

Traditionally, deep-sea ecosystems have been considered to be insulated from the effects of modern climate change. Yet, with the recognition of the importance of food supply from the surface ocean and deep-sea currents to sustaining these systems, the potential for rapid response of benthic systems to climate change is gaining increasing attention. North Atlantic benthic responses to past climate change have been well-documented using marine sediment cores on glacial-interglacial timescales, and ocean sediments have also begun to reveal that planktic species assemblages are already being influenced by global warming. However, very few ecological time-series exist for the deep ocean covering the Holocene-through-industrial era. Here, we use benthic and planktic foraminifera found in Northeast Atlantic (EN539-MC16-A/B and RAPID-17-5P), Northwest Atlantic (KNR158-4-10MC and KNR158-4-9GGC) and Labrador Sea (RAPID-35-25B and RAPID-35-14P) sediments to show that, in locations beneath areas of major North Atlantic surface water change, benthic ecosystems have also changed significantly over the industrial era relative to the Holocene. We find that the response of the benthos is dependent on changes in the surface ocean near to the study sites. Our work highlights the spatial heterogeneity of these benthic ecosystem changes and therefore the need for local-regional scale modelling and observations to better understand responses to deep-sea circulation changes and modern surface climate change.&#160;

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Exceptional 20th Century Shifts in Deep-Sea Ecosystems Are Spatially Heterogeneous and Associated With Local Surface Ocean Variability

Frontiers in Marine Science ◽

10.3389/fmars.2021.663009 ◽

2021 ◽

Vol 8 ◽

Author(s):

Charlotte L. O’Brien ◽

Peter T. Spooner ◽

Jack H. Wharton ◽

Eirini Papachristopoulou ◽

Nicolas Dutton ◽

...

Keyword(s):

Climate Change ◽

Deep Sea ◽

Sediment Cores ◽

Regional Scale ◽

Deep Ocean ◽

Small Scale ◽

Surface Ocean ◽

Spatial Coverage ◽

Major Surface ◽

Benthic Ecosystems

Traditionally, deep-sea ecosystems have been considered to be insulated from the effects of modern climate change, but with the recognition of the importance of food supply from the surface ocean and deep-sea currents to sustaining these systems, the potential for rapid response of benthic systems to climate change is gaining increasing attention. However, very few ecological time-series exist for the deep ocean covering the twentieth century. Benthic responses to past climate change have been well-documented using marine sediment cores on glacial-interglacial timescales, and ocean sediments have also begun to reveal that planktic species assemblages are already being influenced by global warming. Here, we use benthic foraminifera found in mid-latitude and subpolar North Atlantic sediment cores to show that, in locations beneath areas of major surface water change, benthic ecosystems have also changed significantly over the last ∼150 years. The maximum benthic response occurs in areas which have seen large changes in surface circulation, temperature, and/or productivity. We infer that the observed surface-deep ocean coupling is due to changes in the supply of organic matter exported from the surface ocean and delivered to the seafloor. The local-to-regional scale nature of these changes highlights that accurate projections of changes in deep-sea ecosystems will require (1) increased spatial coverage of deep-sea proxy records, and (2) models capable of adequately resolving these relatively small-scale oceanographic features.

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Deep Sea Ostracodes and Climate Change

The Paleontological Society Papers ◽

10.1017/s1089332600002230 ◽

2003 ◽

Vol 9 ◽

pp. 247-264 ◽

Cited By ~ 9

Author(s):

Thomas M. Cronin ◽

Gary S. Dwyer

Keyword(s):

Climate Change ◽

Ocean Circulation ◽

Deep Sea ◽

Global Climate ◽

Sediment Cores ◽

Deep Ocean ◽

Bottom Water Temperature ◽

Shell Chemistry ◽

Practical Guidelines ◽

Deep Ocean Circulation

Ostracodes are bivalved Crustacea whose fossil shells constitute the most abundant and diverse metazoan group preserved in sediment cores from deep and intermediate ocean water depths. The ecology, zoogeography, and shell chemistry of many ostracode taxa makes them useful for paleoceanographic research on topics ranging from deep ocean circulation, bottom-water temperature, ecological response to global climate change and many others. However, the application of ostracodes to the study of climate change has been hampered by a number of factors, including the misconception that they are rare or absent in deep-sea sediments and the lack of taxonomic and zoogeographic data. In recent years studies from the Atlantic, Pacific, and Arctic Oceans show that ostracodes are abundant enough for quantitative assemblage analysis and that the geochemistry of their shells can be a valuable tool for paleotemperature reconstruction. This paper presents practical guidelines for using ostracodes in investigations of climate-driven ocean variability and the ecological and evolutionary impacts of these changes.

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Eastern North Atlantic deep-sea corals: tracing upper intermediate water Δ14C during the Holocene

Earth and Planetary Science Letters ◽

10.1016/s0012-821x(03)00721-0 ◽

2004 ◽

Vol 219 (3-4) ◽

pp. 297-309 ◽

Cited By ~ 80

Author(s):

Norbert Frank ◽

Martine Paterne ◽

Linda Ayliffe ◽

Tjeerd van Weering ◽

Jean-Pierre Henriet ◽

...

Keyword(s):

North Atlantic ◽

Deep Sea ◽

Intermediate Water ◽

The Holocene ◽

Deep Sea Corals ◽

Eastern North Atlantic

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The Search for Supernova-Produced Radionuclides in Terrestrial Deep-Sea Archives

Publications of the Astronomical Society of Australia ◽

10.1071/as11070 ◽

2012 ◽

Vol 29 (2) ◽

pp. 109-114 ◽

Cited By ~ 14

Author(s):

J. Feige ◽

A. Wallner ◽

S. R. Winkler ◽

S. Merchel ◽

L. K. Fifield ◽

...

Keyword(s):

Solar System ◽

Marine Sediment ◽

Deep Sea ◽

Massive Stars ◽

Sediment Cores ◽

Deep Ocean ◽

Transport Mechanisms ◽

Supernova Shell ◽

Process Element ◽

Insight Into

AbstractAn enhanced concentration of 60Fe was found in a deep ocean crust in 2004 in a layer corresponding to an age of ∼2 Myr. The confirmation of this signal in terrestrial archives as supernova-induced and the detection of other supernova-produced radionuclides is of great interest. We have identified two suitable marine sediment cores from the South Australian Basin and estimated the intensity of a possible signal of the supernova-produced radionuclides 26Al, 53Mn, 60Fe, and the pure r-process element 244Pu in these cores. The finding of these radionuclides in a sediment core might allow us to improve the time resolution of the signal and thus to link the signal to a supernova event in the solar vicinity ∼2 Myr ago. Furthermore, it gives us an insight into nucleosynthesis scenarios in massive stars, condensation into dust grains and transport mechanisms from the supernova shell into the solar system.

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Substantial accumulation of mercury in the deepest parts of the ocean and implications for the environmental mercury cycle

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2102629118 ◽

2021 ◽

Vol 118 (51) ◽

pp. e2102629118

Author(s):

Maodian Liu ◽

Wenjie Xiao ◽

Qianru Zhang ◽

Shengliu Yuan ◽

Peter A. Raymond ◽

...

Keyword(s):

Organic Carbon ◽

Food Webs ◽

Deep Sea ◽

Anthropogenic Activities ◽

Sediment Cores ◽

Anthropogenic Sources ◽

Biogeochemical Cycle ◽

Vertical Profiles ◽

Surface Ocean ◽

Increasing Trends

Anthropogenic activities have led to widespread contamination with mercury (Hg), a potent neurotoxin that bioaccumulates through food webs. Recent models estimated that, presently, 200 to 600 t of Hg is sequestered annually in deep-sea sediments, approximately doubling since industrialization. However, most studies did not extend to the hadal zone (6,000- to 11,000-m depth), the deepest ocean realm. Here, we report on measurements of Hg and related parameters in sediment cores from four trench regions (1,560 to 10,840 m), showing that the world’s deepest ocean realm is accumulating Hg at remarkably high rates (depth-integrated minimum–maximum: 24 to 220 μg ⋅ m−2 ⋅ y−1) greater than the global deep-sea average by a factor of up to 400, with most Hg in these trenches being derived from the surface ocean. Furthermore, vertical profiles of Hg concentrations in trench cores show notable increasing trends from pre-1900 [average 51 ± 14 (1σ) ng ⋅ g−1] to post-1950 (81 ± 32 ng ⋅ g−1). This increase cannot be explained by changes in the delivery rate of organic carbon alone but also need increasing Hg delivery from anthropogenic sources. This evidence, along with recent findings on the high abundance of methylmercury in hadal biota [R. Sun et al., Nat. Commun. 11, 3389 (2020); J. D. Blum et al., Proc. Natl. Acad. Sci. U. S. A. 117, 29292–29298 (2020)], leads us to propose that hadal trenches are a large marine sink for Hg and may play an important role in the regulation of the global biogeochemical cycle of Hg.

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Influence of Water Masses on the Biodiversity and Biogeography of Deep-Sea Benthic Ecosystems in the North Atlantic

Frontiers in Marine Science ◽

10.3389/fmars.2020.00239 ◽

2020 ◽

Vol 7 ◽

Cited By ~ 3

Author(s):

Patricia Puerta ◽

Clare Johnson ◽

Marina Carreiro-Silva ◽

Lea-Anne Henry ◽

Ellen Kenchington ◽

...

Keyword(s):

North Atlantic ◽

Deep Sea ◽

Water Masses ◽

The North ◽

Influence Of Water ◽

The North Atlantic ◽

Benthic Ecosystems

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The role of the deep ocean in North Atlantic climate change between 70 and 130 kyr ago

Nature ◽

10.1038/371323a0 ◽

1994 ◽

Vol 371 (6495) ◽

pp. 323-326 ◽

Cited By ~ 155

Author(s):

L. D. Keigwin ◽

W. B. Curry ◽

S. J. Lehman ◽

S. Johnsen

Keyword(s):

Climate Change ◽

North Atlantic ◽

Deep Ocean ◽

North Atlantic Climate

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Reconstructing 7000 years of North Atlantic hurricane variability using deep-sea sediment cores from the western Great Bahama Bank

Paleoceanography ◽

10.1002/palo.20012 ◽

2013 ◽

Vol 28 (1) ◽

pp. 31-41 ◽

Cited By ~ 35

Author(s):

Michael R. Toomey ◽

William B. Curry ◽

Jeffrey P. Donnelly ◽

Peter J. van Hengstum

Keyword(s):

North Atlantic ◽

Deep Sea ◽

Sediment Cores ◽

Deep Sea Sediment ◽

Great Bahama Bank ◽

Atlantic Hurricane

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The Holocene dynamics of Ryder Glacier and ice tongue in north Greenland

The Cryosphere ◽

10.5194/tc-15-4073-2021 ◽

2021 ◽

Vol 15 (8) ◽

pp. 4073-4097

Author(s):

Matt O'Regan ◽

Thomas M. Cronin ◽

Brendan Reilly ◽

Aage Kristian Olsen Alstrup ◽

Laura Gemery ◽

...

Keyword(s):

Climate Change ◽

Late Holocene ◽

Sediment Cores ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Sedimentary Facies ◽

Climate Forcing ◽

The Holocene ◽

Middle Holocene ◽

Vulnerability To Climate Change

Abstract. The northern sector of the Greenland Ice Sheet is considered to be particularly susceptible to ice mass loss arising from increased glacier discharge in the coming decades. However, the past extent and dynamics of outlet glaciers in this region, and hence their vulnerability to climate change, are poorly documented. In the summer of 2019, the Swedish icebreaker Oden entered the previously unchartered waters of Sherard Osborn Fjord, where Ryder Glacier drains approximately 2 % of Greenland's ice sheet into the Lincoln Sea. Here we reconstruct the Holocene dynamics of Ryder Glacier and its ice tongue by combining radiocarbon dating with sedimentary facies analyses along a 45 km transect of marine sediment cores collected between the modern ice tongue margin and the mouth of the fjord. The results illustrate that Ryder Glacier retreated from a grounded position at the fjord mouth during the Early Holocene (> 10.7±0.4 ka cal BP) and receded more than 120 km to the end of Sherard Osborn Fjord by the Middle Holocene (6.3±0.3 ka cal BP), likely becoming completely land-based. A re-advance of Ryder Glacier occurred in the Late Holocene, becoming marine-based around 3.9±0.4 ka cal BP. An ice tongue, similar in extent to its current position was established in the Late Holocene (between 3.6±0.4 and 2.9±0.4 ka cal BP) and extended to its maximum historical position near the fjord mouth around 0.9±0.3 ka cal BP. Laminated, clast-poor sediments were deposited during the entire retreat and regrowth phases, suggesting the persistence of an ice tongue that only collapsed when the glacier retreated behind a prominent topographic high at the landward end of the fjord. Sherard Osborn Fjord narrows inland, is constrained by steep-sided cliffs, contains a number of bathymetric pinning points that also shield the modern ice tongue and grounding zone from warm Atlantic waters, and has a shallowing inland sub-ice topography. These features are conducive to glacier stability and can explain the persistence of Ryder's ice tongue while the glacier remained marine-based. However, the physiography of the fjord did not halt the dramatic retreat of Ryder Glacier under the relatively mild changes in climate forcing during the Holocene. Presently, Ryder Glacier is grounded more than 40 km seaward of its inferred position during the Middle Holocene, highlighting the potential for substantial retreat in response to ongoing climate change.

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Dating rapid climate change in the North Atlantic during Heinrich Stadial 1

10.5194/egusphere-egu2020-18942 ◽

2020 ◽

Author(s):

Andrea Burke ◽

Rosanna Greenop ◽

James Rae ◽

Rhian Rees-Owen ◽

Paula Reimer ◽

...

Keyword(s):

Climate Change ◽

Ocean Circulation ◽

North Atlantic ◽

Sediment Cores ◽

Last Deglaciation ◽

Large Reservoir ◽

The North ◽

The Last Deglaciation ◽

The North Atlantic ◽

Reservoir Age

Paleoclimate records from the North Atlantic show some of the most iconic signals of abrupt climate change during the ice ages. Here we use radiocarbon as a tracer of ocean circulation and air-sea gas exchange to investigate potential mechanisms for the abrupt climate changes seen in the North Atlantic over the last deglaciation. We have created a stack of North Atlantic surface radiocarbon reservoir ages over the past 20,000 years, using new synchronized age models from thirteen sediment cores refined with thorium normalization between tie-points. This stack shows consistent and large reservoir age increases of more than 1000 years from the LGM into HS1, dropping abruptly back to approximately modern reservoir ages before the onset of the Bolling-Allerod. We use the intermediate complexity earth system model cGENIE to investigate the potential drivers of these reservoir age changes. We find that sea ice, circulation and CO2 all play important roles in setting the reservoir age. We use these coherently dated records to revisit the sequence and timing of climatic events during HS1 and the last deglaciation, and show that Laurentide Heinrich Events are a response to stadial conditions, rather than their root cause.

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