Calcium carbonate dissolution patterns in the ocean

Nature Geoscience, Journal Year: 2021, Volume and Issue: 14(6), P. 423 - 428

Published: May 10, 2021

Language: Английский

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Aragonite dissolution protects calcite at the seafloor

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: March 1, 2022

Abstract In the open ocean, calcium carbonates are mainly found in two mineral forms. Calcite, least soluble, is widespread at seafloor, while aragonite, more rarely preserved marine sediments. Despite its greater solubility, research has shown that whose contribution to global pelagic calcification could be par with of calcite, able reach deep-ocean. If large quantities aragonite settle and dissolve this represents a source alkalinity buffers deep ocean favours preservation less soluble acting as deep-sea, carbonate version galvanization. Here, we investigate role dissolution on early diagenesis calcite-rich sediments using novel 3D, micrometric-scale reactive-transport model combined X-ray tomography structures natural calcite shells. Results highlight important diffusive transport benthic dissolution, agreement recent work. We show that, locally, fluxes seafloor sufficient suppress top layer seabed, possibly causing recrystallization. As producers particularly vulnerable acidification, proposed galvanizing effect weakened future, sediment-water interface will have cover share CO 2 neutralization.

Language: Английский

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Pelagic calcium carbonate production and shallow dissolution in the North Pacific Ocean

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Feb. 20, 2023

Abstract Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO 2 . Surprisingly, references to the absolute relative contribution of these calcium production are lacking. Here we report quantification pelagic North Pacific, providing new insights on three main planktonic groups. Our results show that coccolithophores dominate living (CaCO 3 ) standing stock, with coccolithophore calcite comprising ~90% total CaCO production, pteropods foraminifera playing secondary role. We is higher than sinking flux at 150 200 m stations ALOHA PAPA, implying large portion remineralised within photic zone; this extensive shallow dissolution explains apparent discrepancy between previous estimates derived from satellite observations/biogeochemical modeling versus sediment traps. suggest future changes cycle its impact will largely depend how poorly-understood processes determine whether zone or exported depth respond anthropogenic warming acidification.

Language: Английский

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3D morphological variability in foraminifera unravel environmental changes in the Baltic Sea entrance over the last 200 years

Frontiers in Earth Science, Journal Year: 2023, Volume and Issue: 11

Published: April 3, 2023

Human activities in coastal areas have intensified over the last 200 years, impacting also high-latitude regions such as Baltic Sea. Benthic foraminifera, protists often with calcite shells (tests), are typically well preserved marine sediments and known to record past bottom-water conditions. Morphological analyses of acquired by microcomputed tomography (µCT) made significant progress toward a better understanding recent environmental changes. However, limited access data processing lack guidelines persist when using open-source software adaptable different microfossil shapes. This study provides post-data routine analyze entire test parameters: average thickness, volume, surface area, number pores, pore density, area/volume ratio. A case was used illustrate this method: 3D time series (i.e., 4D) Elphidium clavatum specimens recording conditions Sea entrance from period early industrial (the 1800s) present-day 2010 s). Long-term morphological trends foraminiferal revealed that modern ∼28% thinner tests ∼91% more pores than their historic counterparts. variability between BFAR (specimens cm −2 yr −1 ) E. were not always synchronous. While remained unchanged, linked natural fluctuations consequences anthropogenic climate change 21st century. During 1940–2000 s, variations synchronous variability, revealing both effects increase human major hydrographic Finally, our interpretations, based on variations, highlight changes supporting those documented assemblages.

Language: Английский

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Shell density of planktonic foraminifera and pteropod species Limacina helicina in the Barents Sea: Relation to ontogeny and water chemistry

PLoS ONE, Journal Year: 2021, Volume and Issue: 16(4), P. e0249178 - e0249178

Published: April 28, 2021

Planktonic calcifiers, the foraminiferal species Neogloboquadrina pachyderma and Turborotalita quinqueloba , thecosome pteropod Limacina helicina from plankton tows surface sediments northern Barents Sea were studied to assess how shell density varies with depth habitat ontogenetic processes. The shells measured using X-ray microcomputed tomography (XMCT) scanning compared physical chemical properties of water column including carbonate chemistry calcium saturation calcite aragonite. Both living L . N increased in 300 m depth. 150–200 Deeper than 150 m, T experienced a loss due internal dissolution, possibly related gametogenesis. recently settled (dead) specimens planktonic foraminifera sediment samples was fauna showed large range dissolution states. This not apparent shell-surface texture, especially for which tended be both thicker denser Dissolution lowered while thickness remained intact. also increase size thicken apex growth. study demonstrates that this specific area did suffer effects. occurred after death settling on sea floor. shows biomonitoring is important understanding natural variability calcifying zooplankton.

Language: Английский

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Constraining CaCO₃ Export and Dissolution With an Ocean Alkalinity Inverse Model

Global Biogeochemical Cycles, Journal Year: 2023, Volume and Issue: 37(2)

Published: Jan. 24, 2023

Abstract Ocean alkalinity plays a fundamental role in the apportionment of CO 2 between atmosphere and ocean. The primary driver ocean's vertical distribution is formation calcium carbonate (CaCO 3 ) by organisms at ocean surface its dissolution depth. This so‐called “CaCO counterpump” poorly constrained, however, both terms how much CaCO exported from ocean, what depth it dissolves. Here, we created steady‐state model global using Circulation Inverse Model transport, biogeochemical cycling, field‐tested calcite aragonite kinetics. We find that limiting to below saturation horizons cannot explain excess upper models allowing above best match observations. Linking organic matter respiration, or imposing constant rate produce good fits. Our performing require export 1.1 1.8 Gt PIC y −1 (from 73 m), but all converge 1.0 279 m, indicating high‐ low‐export scenarios can observations, as long high coupled These results demonstrate not simple function seawater (Ω) solubility, other mechanisms, likely related biology ecology calcifiers, must drive significant throughout water column.

Language: Английский

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Eight new records of the family Cavoliniidae (Gastropoda: Pteropoda) from the Andaman Islands, India

Journal of the Marine Biological Association of the United Kingdom, Journal Year: 2025, Volume and Issue: 105

Published: Jan. 1, 2025

Abstract This research focuses on pteropods of the family Cavoliniidae, which remains an under-studied taxa in Indian waters. Sediment samples collected by FORV Sagar Sampada from Andaman Islands, India, yielded eight species representing genera Cavolinia and Diacavolinia subfamily Cavoliniinae, genus Diacria Diacriniinae. Notably, four – aspina , D. bandaensis deblainvillei erythra represent new distributional records for India. Furthermore, uncinata angulata bicornis flexipes are recorded first time Sea. study is significant expanding understanding pteropod diversity Ocean, contributing to a better their ecosystem geographical range.

Language: Английский

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Contrasting life cycles of Southern Ocean pteropods alter their vulnerability to climate change

Frontiers in Marine Science, Journal Year: 2023, Volume and Issue: 10

Published: May 11, 2023

Pteropods are a key part of biogeochemical cycling and epipelagic food webs in the Southern Ocean. However, shelled pteropods vulnerable to climate change, due their aragonite shells being particularly sensitive ocean acidification. Currently our understanding pteropod responses environmental change is hindered by uncertainties surrounding life cycles population dynamics. In this study, we describe polar diversity north-eastern Scotia Sea, inferring history structures dominant species, Limacina rangii (formerly helicina antarctica ) retroversa . An annual timeseries shell morphometrics was derived from individuals collected moored sediment trap at 400 m depth. We found that L. have contrasting strategies. has continuous spawning recruitment period November March can overwinter as juveniles adults. discrete events May, producing non–overlapping cohorts Their development adult stage takes between two five months, upon which they Our findings suggest different vulnerabilities changing ocean. For example, since all stages co-exist, vulnerability one cohort not detrimental stability overall whereas, if fails recruit, entire threatened. Changes populations could cascading ramifications Antarctic ecosystems carbon cycling.

Language: Английский

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Interannual variability (2000–2013) of mesopelagic and bathypelagic particle fluxes in relation to variable sea ice cover in the eastern Fram Strait

Frontiers in Earth Science, Journal Year: 2023, Volume and Issue: 11

Published: June 28, 2023

The Fram Strait connects the Atlantic and Arctic Oceans is a key conduit for sea ice advected southward by Transpolar Drift northward inflow of warm Waters. Continued decline “Atlantification” are expected to influence pelagic–benthic coupling in as whole. However, interannual variability impact changing conditions on deepwater particle fluxes remain poorly characterized. Here, we present long-term sediment trap records (2000–2013) from mesopelagic (200 m) bathypelagic (2,300 depths at two locations (HGIV HGN) subjected variable conditions. Sediment catchment areas were estimated combined with remote sensing data high-resolution model determine cover, chlorophyll concentration, prevailing stratification regimes. Surface increased between 2000 2013, but there was no corresponding increase POC flux, suggesting shift efficiency biological carbon pump. A decrease particulate biogenic Si %opal, Si:POC, Si:PIC indicates away diatom-dominated export feasible explanation. Biogenic components accounted 72% ± 16% mass flux 200 m, reduced 34% 11% 2,300 substituted residual (lithogenic) material. Total components, including POC, higher bathypelagic. Biomarkers ∂ 13 C values suggest both lateral advection ice-rafted material contribute benthic input, although constraining their precise contribution remains challenging. decadal time series used describe end-members area representing maximum temperatures water 2005 HGIV high coverage meltwater regime HGN 2007. Despite similar concentrations, POC:PIC lower high-ice/meltwater regime. Our findings that concentration associated regimes cause diatom flux. It possible this will future increase, it likely be transient feature disappear when remains.

Language: Английский

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Determining how biotic and abiotic variables affect the shell condition and parameters of <i>Heliconoides inflatus</i> pteropods from a sediment trap in the Cariaco Basin

Biogeosciences, Journal Year: 2020, Volume and Issue: 17(7), P. 1975 - 1990

Published: April 14, 2020

Abstract. Pteropods have been nicknamed the “canary in coal mine” for ocean acidification because they are predicted to be among first organisms affected by changing chemistry. This is due their fragile, aragonitic shells and high abundances polar subpolar regions where impacts of most pronounced. For pteropods used effectively as indicators acidification, biotic abiotic factors influencing shell formation dissolution modern need quantified understood. Here, we measured condition (i.e., degree which a has dissolved) characteristics, including size, number whorls, thickness, volume amount material) nearly 50 specimens pteropod species Heliconoides inflatus sampled from sediment trap Cariaco Basin, Venezuela, over an 11-month period. The traps potential altered at three stages: (1) when live water column associated with (2) dead decay organic matter and/or (3) closed cup alteration preservation solution. Shell was assessed using two methods: Limacina Dissolution Index (LDX) opacity method. method found capture changes only early stages dissolution, whereas LDX recorded much larger range. Because Basin supersaturated respect aragonite year-round, assume no occurred during life, there evidence that deteriorated length time trap. Light microscope scanning electron (SEM) images show majority happened while matter. samples collected September October temperatures were warmest degradation, both within column, likely greatest. hydrographic chemical properties vary seasonally movement Intertropical Convergence Zone (ITCZ). Shells H. varied thickness throughout year. There not strong correlation between whorls diameter, suggesting growth plastic. formed 40 % thicker 20 diameter nutrient-rich, upwelling times food supply abundant, indicating this aragonite-supersaturated basin controlled availability. study produces baseline dataset variability characteristics documents controls on captured via traps. methodology outlined assessing parameters establishes protocol generating similar records populations globally.

Language: Английский

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