Rapid 20th-century increase in coastal upwelling off northwest Africa revealed by high-resolution marine sediment cores

AbstractEnvironmental DNA (eDNA) can be a powerful tool for detecting the distribution and abundance of target species. This study aimed to test the longevity of eDNA in marine sediment through a tank experiment and to use this information to reconstruct past faunal occurrence. In the tank experiment, juvenile jack mackerel (Trachurus japonicus) were kept in flow-through tanks with marine sediment for two weeks. Water and sediment samples from the tanks were collected after the removal of fish. In the field trial, sediment cores were collected in Moune Bay, northeast Japan, where unusual blooms of jellyfish (Aurelia sp.) occurred after a tsunami. The samples were analyzed by layers to detect the eDNA of jellyfish. The tank experiment revealed that after fish were removed, eDNA was not present in the water the next day, or subsequently, whereas eDNA was detectable in the sediment for 12 months. In the sediment core samples, jellyfish eDNA was detected at high concentrations above the layer with the highest content of polycyclic aromatic hydrocarbons, reflecting tsunami-induced oil spills. Thus, marine sediment eDNA preserves a record of target species for at least one year and can be used to reconstruct past faunal occurrence.

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Mercury pollution in marine sediment cores near cinnabar deposits and a chlor-alkali plant

The Science of The Total Environment ◽

10.1016/0048-9697(86)90016-1 ◽

1986 ◽

Vol 57 ◽

pp. 111-120 ◽

Cited By ~ 14

Author(s):

Franco Baldi ◽

Maria L. D'Amato

Keyword(s):

Marine Sediment ◽

Sediment Cores ◽

Mercury Pollution

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High-resolution radiocarbon dating to reconstruct last century environmental changes in the pacific island of Espiritu Santo

10.5194/egusphere-egu21-15449 ◽

2021 ◽

Author(s):

Giorgia Camperio ◽

Caroline Welte ◽

S. Nemiah Ladd ◽

Matthew Prebble ◽

Nathalie Dubois

Keyword(s):

High Resolution ◽

Radiocarbon Dating ◽

Environmental Changes ◽

Accumulation Rate ◽

Sediment Cores ◽

Volcanic Eruptions ◽

High Accumulation ◽

Sedimentary Records ◽

The Pacific ◽

Rapid Accumulation

<p>Espiritu Santo is one of the 82 islands of the archipelago of Vanuatu and is the largest, highest, and most biodiverse of the insular country. Climatic changes linked to El Ni&#241;o and extreme events such as cyclones and volcanic eruptions are a daily challenge in this remote area. These events can be recorded in sedimentary archives. Here we present a multi-proxy investigation of sediment cores retrieved from two small lakes located on the West coast of Espiritu Santo. Although the records span the last millennium, high-resolution radiocarbon dating of macrofossils reveals a rapid accumulation of sediment in the past 100 years. The high accumulation rate coupled with the high-resolution dating of freshwater sediments allows us to compare the <sup>14</sup>C bomb curve with the biogeochemical proxies of the sedimentary records. The results can then be validated against written and oral historical records linked with the societal perception of recent environmental changes in this vulnerable ecosystem.</p><div> <div title="Translate selected text"></div> <div title="Play"></div> <div title="Copy text to Clipboard"></div> </div>

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A 2400 yr record of natural events and anthropogenic impacts in intercorrelated terrestrial and marine sediment cores: Waipaoa sedimentary system, New Zealand

Geological Society of America Bulletin ◽

10.1130/b25996.1 ◽

2007 ◽

Vol 119 (11-12) ◽

pp. 1415-1432 ◽

Cited By ~ 42

Author(s):

B. Gomez ◽

L. Carter ◽

N. A. Trustrum

Keyword(s):

New Zealand ◽

Marine Sediment ◽

Anthropogenic Impacts ◽

Sediment Cores ◽

Sedimentary System

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Trends in coastal upwelling intensity during the late 20th century

Ocean Science ◽

10.5194/os-6-815-2010 ◽

2010 ◽

Vol 6 (3) ◽

pp. 815-823 ◽

Cited By ~ 88

Author(s):

N. Narayan ◽

A. Paul ◽

S. Mulitza ◽

M. Schulz

Keyword(s):

20Th Century ◽

Wind Stress ◽

Coastal Upwelling ◽

Meridional Wind ◽

Steady Increase ◽

Late 20Th Century ◽

North West ◽

Basin Scale ◽

Upwelling Intensity ◽

Instrumental Records

Abstract. This study presents linear trends of coastal upwelling intensity in the later part of the 20th century (1960–2001) employing various indices of upwelling, derived from meridional wind stress and sea surface temperature. The analysis was conducted in the four major coastal upwelling regions in the world, which are off North-West Africa, Lüderitz, California and Peru. The trends in meridional wind stress showed a steady increase of intensity from 1960–2001, which was also reflected in the SST index calculated for the same time period. The steady cooling observed in the instrumental records of SST off California substantiated this observation further. It was also noted that the trends in meridional wind stress obtained from different datasets differ substantially from each other. Correlation analysis showed that basin-scale oscillations like the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO) could not be directly linked to the observed increase of upwelling intensity off NW Africa and California respectively. The relationship of the North Atlantic Oscillation (NAO) with coastal upwelling off NW Africa turned out to be ambiguous due to a negative correlation between the NAO index and the meridional wind stress and a lack of correlation with the SST index. Our results give additional support to the hypothesis that the coastal upwelling intensity increases globally because of raising greenhouse gas concentrations in the atmosphere and an associated increase of the land-sea pressure gradient and meridional wind stress.

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Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

Biogeosciences ◽

10.5194/bg-9-1041-2012 ◽

2012 ◽

Vol 9 (3) ◽

pp. 1041-1051 ◽

Cited By ~ 22

Author(s):

C. Zindler ◽

I. Peeken ◽

C. A. Marandino ◽

H. W. Bange

Keyword(s):

Surface Waters ◽

Coastal Upwelling ◽

Environmental Control ◽

Hot Spot ◽

Local Source ◽

Surface Seawater ◽

Near Surface ◽

Northwest Africa ◽

N:P Ratios ◽

A Minor

Abstract. Dimethylsulphide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in near-surface waters along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. However, the DMS concentrations measured are in the low range compared to other upwelling regions. The maximum DMSPp concentration is the highest reported from upwelling regions so far, which might indicate that the Mauritanian upwelling is a hot spot for DMSP. Within the phytoplankton groups, dinoflagellates were identified as important contributors to DMS concentrations, while other algae seemed to have only a minor or no influence on DMS and DMSP concentrations. A pronounced switch from high DMSP to high DMS concentrations was observed when the nitrogen to phosphorus ratio (N:P) was below 7. The high DMS/DMSP ratios at N:P ratios <7 indicate that nitrogen limitation presumably triggered a switch from DMSP to DMS independent of the species composition. Our results underline the importance of coastal upwelling regions as a local source for surface seawater sulphur.

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Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

Biogeosciences Discussions ◽

10.5194/bgd-8-8591-2011 ◽

2011 ◽

Vol 8 (4) ◽

pp. 8591-8618

Author(s):

C. Zindler ◽

I. Peeken ◽

C. A. Marandino ◽

H. W. Bange

Keyword(s):

Nitrogen Limitation ◽

Coastal Upwelling ◽

Environmental Control ◽

Hot Spot ◽

Northwest Africa ◽

Induced Stress ◽

Temporal And Spatial Variability ◽

Temporal And Spatial ◽

A Minor ◽

The Tropics

Abstract. Dimethylsulfide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in sea surface layer along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. The maximum DMSPp concentration is the highest reported from upwelling regions so far and indicates that the Mauritanian upwelling is a hot spot of DMSP and, thus, DMS production. Dinoflagellates were responsible for the DMS production. Other phytoplankton groups seemed to have only a minor or no influence on the DMS and DMSP production. Decreasing nitrogen (i.e. increasing nitrogen limitation) most likely triggered a switch from high DMSP production to high DMS production. It seems that both nitrogen limitation and the intensive solar radiation in the tropics induced stress in DMSP producing algae and activated their antioxidant system. Our results underline the importance of coastal upwelling regions as ecosystems with a pronounced temporal and spatial variability which result in high DMSP and DMS production.

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Nutrient regime and upwelling in the northern Benguela since the middle Holocene in a global context – a multi-proxy approach

Fossil Record ◽

10.5194/fr-14-171-2011 ◽

2011 ◽

Vol 14 (2) ◽

pp. 171-193 ◽

Cited By ~ 3

Author(s):

S. Meisel ◽

K.-C. Emeis ◽

U. Struck ◽

I. Kristen

Keyword(s):

South African ◽

Coastal Upwelling ◽

Sediment Cores ◽

Nutrient Content ◽

Ice Age ◽

Global Ocean ◽

Source Water ◽

Environmental Response ◽

Global Context ◽

Source Water Quality

The last 5500 years of climate change and environmental response in the northern Benguela Coastal Upwelling are reconstructed by means of three sediment cores from the inner shelf off central Namibia. The study is based on nutrient (δ<sup>15</sup>N, δ<sup>13</sup>C) and productivity proxies (accumulation rates of total organic carbon; AR<sub>TOC</sub>). Reconstructed sea surface temperatures (alkenone-derived SST) and temperatures at subsurface depths (<i>T</i><sub>δ18O</sub>; based on tests of planktonic foraminifers) reflect the physical boundary conditions. The selection of proxy indicators proved a valuable basis for robust palaeo-climatic reconstructions, with the resolution ranging from multi-decadal (NAM1) over centennial (core 178) to millennial scale (core 226620). The northern Benguela experienced pronounced and rapid perturbation during the middle and late Holocene, and apparently, not all are purely local in character. In fact, numerous correlations with records from the adjacent South African subcontinent and the northern hemisphere testify to global climatic teleconnections. The Holocene Hypsithermal, for instance, is just as evident as the Little Ice Age (LIA) and the Roman Warm Period. The marked SST-rise associated with the latter is substantiated by other marine and terrestrial data from the South African realm. The LIA (at least its early stages) manifests itself in intensified winds and upwelling, which accords with increased rainfall receipts above the continental interior. It appears that climate signals are transferred both via the atmosphere and ocean. The combined analysis of SST and <i>T</i><sub>δ18O</sub> proved a useful tool in order to differentiate between both pathways. SSTs are primarily controlled by the intensity of atmospheric circulation features, reflecting changes of upwelling-favourable winds. <i>T</i><sub>δ18O</sub> records the temperature of the source water and often correlates with global ocean conveyor speed due to varying inputs of warm Agulhas Water. It seems as though conveyor slowdown or acceleration not only affected the temperature of the source water but also its nutrient content. This relationship between source water quality and conveyor speed is already known from glacial times. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.201100006" target="_blank">10.1002/mmng.201100006</a>

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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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