Eric P. Achterberg

GEOMAR Helmholtz Centre for Ocean Research Kiel

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i-10 index

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Martha Gledhill

GEOMAR Helmholtz Centre for Ocean Research Kiel

Mark J. Hopwood

Southern University of Science and Technology

Lennart T. Bach

University of Tasmania

Ulf Riebesell

GEOMAR Helmholtz Centre for Ocean Research Kiel

Thomas J. Browning

GEOMAR Helmholtz Centre for Ocean Research Kiel

C. Mark Moore

University of Southampton

Christian Schlösser

GEOMAR Helmholtz Centre for Ocean Research Kiel

Paul J. Worsfold

University of Plymouth

Simon J. Ussher

University of Plymouth

Maeve C. Lohan

National Oceanography Centre

Cooperative Institutions

GEOMAR Helmholtz Centre for Ocean Research Kiel

237

National Oceanography Centre

216

University of Southampton

201

Centre National de la Recherche Scientifique

142

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Institut de Recherche pour le Développement

Woods Hole Oceanographic Institution

Kiel University

Xiamen University

University of Plymouth

Author Statistics

Papers

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Research Field

Distribution of size fractionated dissolved iron in the Canary Basin

Marine Environmental Research (2010)

Simon J. Ussher Eric P. Achterberg Géraldine Sarthou Patrick Laan H. J. W. de Baar

10.1016/j.marenvres.2010.03.001

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Citations (38)

Review article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

The cryosphere (2020)

Mark J. Hopwood Dustin Carroll Thorben Dunse Andy Hodson Johnna M. Holding

Abstract. Freshwater discharge from glaciers is increasing across the Arctic in response to anthropogenic climate change, which raises questions about the potential downstream effects in the marine environment. Whilst a combination of long-term monitoring programmes and intensive Arctic field campaigns have improved our knowledge of glacier–ocean interactions in recent years, especially with respect to fjord/ocean circulation, there are extensive knowledge gaps concerning how glaciers affect marine biogeochemistry and productivity. Following two cross-cutting disciplinary International Arctic Science Committee (IASC) workshops addressing the importance of glaciers for the marine ecosystem, here we review the state of the art concerning how freshwater discharge affects the marine environment with a specific focus on marine biogeochemistry and biological productivity. Using a series of Arctic case studies (Nuup Kangerlua/Godthåbsfjord, Kongsfjorden, Kangerluarsuup Sermia/Bowdoin Fjord, Young Sound and Sermilik Fjord), the interconnected effects of freshwater discharge on fjord–shelf exchange, nutrient availability, the carbonate system, the carbon cycle and the microbial food web are investigated. Key findings are that whether the effect of glacier discharge on marine primary production is positive or negative is highly dependent on a combination of factors. These include glacier type (marine- or land-terminating), fjord–glacier geometry and the limiting resource(s) for phytoplankton growth in a specific spatio-temporal region (light, macronutrients or micronutrients). Arctic glacier fjords therefore often exhibit distinct discharge–productivity relationships, and multiple case-studies must be considered in order to understand the net effects of glacier discharge on Arctic marine ecosystems.

Fjord

Biogeochemistry

Marine ecosystem

10.5194/tc-14-1347-2020

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Citations (177)

Phytoplankton Diversity and Co-Dependency in a Stratified Oligotrophic Ecosystem in the South Adriatic Sea

Water (2023)

Antonija Matek Maja Mucko Raffaella Casotti Anna Chiara Trano Eric P. Achterberg

The oligotrophy of the southern Adriatic Sea is characterized by seasonal stratification which enables nutrient supply to the euphotic layer. A set of interdisciplinary methods was used to elucidate the diversity and co-dependency of bacterio- and phytoplankton of the water column during the stratification period of July 2021. A total of 95 taxa were determined by microscopy: 58 diatoms, 27 dinoflagellates, 6 coccolithophores, and 4 other autotrophs, which included Chlorophyceae, Chrysophyceae, and Cryptophytes. Nanophytoplankton abundances were higher in comparison to microphytoplankton. The prokaryotic plankton community as revealed by HTS was dominated by Proteobacteria (41–73%), Bacteroidota (9.5–27%), and cyanobacteria (1–10%), while the eukaryotic plankton community was composed of parasitic Syndiniales (45–80%), Ochrophyta (2–18%), Ciliophora (2–21%), Chlorophytes (2–4%), Haptophytes (1–4%), Bacillariophyta (1–13%), Pelagophyta (0.5–12%) and Chrysophyta (0.5–3%). Flow cytometry analysis has recorded Prochlorococcus and photosynthetic picoeukaryotes as more abundant in deep chlorophyll maximum (DCM), and Synechococcus and heterotrophic bacteria as most abundant in surface and thermocline layers. Surface, thermocline, and DCM layers were distinct considering community diversity, temperature, and nutrient correlations, while extreme nutrient values at the beginning of the investigating period indicated a possible nutrient flux. Nutrient and temperature were recognized as the main environmental drivers of phytoplankton and bacterioplankton community abundance.

Bacterioplankton

Prochlorococcus

10.3390/w15122299

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Citations (3)

Arctic – Atlantic Exchange of the Dissolved Micronutrients Iron, Manganese, Cobalt, Nickel, Copper and Zinc With a Focus on Fram Strait

Global Biogeochemical Cycles (2022)

Stephan Krisch Mark J. Hopwood Stéphane Roig Loes J. A. Gerringa Rob Middag

Abstract The Arctic Ocean is considered a source of micronutrients to the Nordic Seas and the North Atlantic Ocean through the gateway of Fram Strait (FS). However, there is a paucity of trace element data from across the Arctic Ocean gateways, and so it remains unclear how Arctic and North Atlantic exchange shapes micronutrient availability in the two ocean basins. In 2015 and 2016, GEOTRACES cruises sampled the Barents Sea Opening (GN04, 2015) and FS (GN05, 2016) for dissolved iron (dFe), manganese (dMn), cobalt (dCo), nickel (dNi), copper (dCu) and zinc (dZn). Together with the most recent synopsis of Arctic‐Atlantic volume fluxes, the observed trace element distributions suggest that FS is the most important gateway for Arctic‐Atlantic dissolved micronutrient exchange as a consequence of Intermediate and Deep Water transport. Combining fluxes from FS and the Barents Sea Opening with estimates for Davis Strait (GN02, 2015) suggests an annual net southward flux of 2.7 ± 2.4 Gg·a −1 dFe, 0.3 ± 0.3 Gg·a −1 dCo, 15.0 ± 12.5 Gg·a −1 dNi and 14.2 ± 6.9 Gg·a −1 dCu from the Arctic toward the North Atlantic Ocean. Arctic‐Atlantic exchange of dMn and dZn were more balanced, with a net southbound flux of 2.8 ± 4.7 Gg·a −1 dMn and a net northbound flux of 3.0 ± 7.3 Gg·a −1 dZn. Our results suggest that ongoing changes to shelf inputs and sea ice dynamics in the Arctic, especially in Siberian shelf regions, affect micronutrient availability in FS and the high latitude North Atlantic Ocean.

Geotraces

Arctic dipole anomaly

Trace element

10.1029/2021gb007191

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Citations (18)

Sources and transport of dissolved iron and manganese along the continental margin of the Bay of Biscay

Biogeosciences (2007)

Agathe Laës Stéphane Blain Patrick Laan Simon J. Ussher Eric P. Achterberg

Abstract. Dissolved iron (DFe; <0.2 µm) and dissolved manganese (DMn; <0.2 µm) concentrations were determined in the water column of the Bay of Biscay (eastern North Atlantic Ocean) in March 2002. The samples were collected along a transect traversing from the European continental shelf over the continental slope. The highest DFe and DMn concentrations (2.39 nM and 6.10 nM, respectively) were observed in the bottom waters on the shelf at stations closest to the coast. The release of trace metal from resuspended particles and the diffusion from pore waters were probably at the origin of elevated DFe and DMn concentrations in the Bottom Boundary Layer (BBL). In the slope region, the highest total dissolvable iron (TDFe), DFe and DMn values (24.6 nM, 1.58 nM and 2.12 nM, respectively) were observed close to the bottom at depth of ca.~600–700 m. Internal wave activity and slope circulation are thought to be at the origin of this phenomenon. These processes were also very likely the cause of elevated concentrations (DFe: 1.27 nM, DMn: 2.34 nM) measured in surface waters of stations located in the same area. At stations off the continental slope, the vertical distribution of both metals were typical of open ocean conditions, indicating that inputs from the continental margin did not impact the metal distributions in the offshore waters.

Continental Margin

Trace metal

10.5194/bg-4-181-2007

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Citations (45)

High resolution dissolved and dissolvable aluminum measurements along the GEOVIDE section (GEOTRACES section GA01)

American Geophysical Union eBooks (2016)

Eric P. Achterberg Jan‐Lukas Menzel Barraqueta Christian Schlösser Hélène Planquette Marie Cheize

Section (typography)

Geotraces

Source

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Citations (0)

High-Precision In Situ Total Alkalinity Analyzer Capable of Month-Long Observations in Seawaters

ACS Sensors (2023)

Li Qiu Quanlong Li Dongxing Yuan Jinshun Chen Jiezhen Xie

Total alkalinity (TA) is an essential variable for the study of physical and biogeochemical processes in coastal and oceanic systems, and TA data obtained at high spatiotemporal resolutions are highly desired. The performance of the current in situ TA analyzers/sensors, including precision, accuracy, and deployment duration, cannot fully meet most research requirements. Here, we report on a novel high-precision in situ analyzer for surface seawater TA (ISA-TA), based on an automated single-point titration with spectrophotometric pH detection, and capable of long-term field observations. The titration was carried out in a circulating loop, where the titrant (a mixture of HCl and bromocresol green) and seawater sample were mixed in a constant volume ratio. The effect of ambient temperature on the TA measurement was corrected with an empirical formula. The weight, height, diameter, and power consumption of ISA-TA were 8.6 kg (in air), 33 cm, 20 cm, and 7.3 W, respectively. A single measurement required ∼7 min of running time, ∼32 mL of seawater, and ∼0.6 mL of titrant. ISA-TA was able to operate continuously in the field for up to 30 days, and its accuracies in the laboratory and field were 0.5 ± 1.7 μmol kg–1 (n = 13) and 10.3 ± 2.8 μmol kg–1 (n = 29) with precisions of 0.6–0.8 μmol kg–1 (n = 51) and 0.2–0.7 μmol kg–1 (n = 8), respectively. This study provides the research community with a new tool to obtain seawater TA data of high temporal resolution.

Alkalinity

Biogeochemical Cycle

10.1021/acssensors.3c00552

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Citations (6)

Influence of Ocean Acidification and Deep Water Upwelling on Oligotrophic Plankton Communities in the Subtropical North Atlantic: Insights from an In situ Mesocosm Study

Frontiers in Marine Science (2017)

Jan Taucher Lennart T. Bach Tim Boxhammer Alice Nauendorf Eric P. Achterberg

Oceanic uptake of anthropogenic carbon dioxide (CO2) causes pronounced shifts in marine carbonate chemistry and a decrease in seawater pH. Increasing evidence indicates that these changes – summarized by the term ocean acidification (OA) – can significantly affect marine food webs and biogeochemical cycles. However, current scientific knowledge is largely based on laboratory experiments with single species and artificial boundary conditions, whereas studies of natural plankton communities are still relatively rare. Moreover, the few existing community-level studies were mostly conducted in rather eutrophic environments, while less attention has been paid to oligotrophic systems such as the subtropical ocean gyres. Here we report from a recent in situ mesocosm experiment off the coast of Gran Canaria in the eastern subtropical North Atlantic, where we investigated the influence of OA on the ecology and biogeochemistry of plankton communities in oligotrophic waters under close-to-natural conditions. This paper is the first in this Research Topic of Frontiers in Marine Biogeochemistry and provides (1) a detailed overview of the experimental design and important events during our mesocosm campaign, and (2) first insights into the ecological responses of plankton communities to simulated OA over the course of the 62-day experiment. One particular scientific objective of our mesocosm experiment was to investigate how OA impacts might differ between oligotrophic conditions and phases of high biological productivity, which regularly occur in response to upwelling of nutrient-rich deep water in the study region. Therefore, we specifically developed a deep water collection system that allowed us to obtain ~85 m3 of seawater from ~650 m depth. Thereby, we replaced ~20% of each mesocosm's volume with deep water, and thus successfully simulated a deep water upwelling event that induced a pronounced plankton bloom. Our study revealed significant effects of OA on the entire food web, leading to a restructuring of plankton communities that emerged during the oligotrophic phase, and was further amplified during the bloom that developed in response to deep water addition. Such CO2-related shifts in plankton community composition could have consequences for ecosystem productivity, biomass transfer to higher trophic levels, and biogeochemical element cycling of oligotrophic ocean regions.

Mesocosm

Biogeochemistry

Ocean Acidification

Biogeochemical Cycle

10.3389/fmars.2017.00085

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Citations (109)

Supplementary material to "Temporal dynamics of surface ocean carbonate chemistry in response to natural and simulated upwelling events during the 2017 coastal El Niño near Callao, Peru"

Shaomin Chen Ulf Riebesell Kai G. Schulz Elisabeth von der Esch Eric P. Achterberg

Table S1: The drawdown of surface DIC, DIN and PO4 3-(μmol L -1 ) in the mesocosms from t13 to t24 following OMZ water addition and the molar ratio of DIC: DIN and DIN: PO4 3-(mol: mol) drawdown.The DIC concentration in μmol L -1 was estimated by applying an approximate seawater density of 1.025 kg L -1 (T = 20 ℃, S = 35 psu, P = 5 dbar).M3 and M4 were excluded from

10.5194/bg-2021-111-supplement

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Citations (1)

Incubation Experiments Characterize Turbid Glacier Plumes as a Major Source of Mn and Co, and a Minor Source of Fe and Si, to Seawater

Global Biogeochemical Cycles (2024)

Xunchi Zhu Mark J. Hopwood Katja Laufer Eric P. Achterberg

Abstract Glaciers are a source of fine‐ground rock flour to proglacial and coastal marine environments. In these environments, suspended rock flour may affect light and (micro)nutrient availability to primary producers. Due to high loads of glacier rock flour, the particulate metal load of glacier runoff typically exceeds the dissolved metal load. As glacier rock flour is deposited in downstream environments, short‐term exchange between particulate and dissolved metal phases may have a moderating influence on dissolved metal concentrations. Here we compare the behavior of iron (Fe), manganese (Mn), cobalt (Co) and silica (Si) following the addition of different glacier‐derived sediments into seawater under conditions of varying sediment load (20–500 mg L −1 ), time (0.5 hr–21 days), temperature (4–11°C) and light exposure (dark/2,500 Lux). Despite a moderately high labile Fe content across all particle types (0.28–3.50 mg Fe g −1 of dry sediment), only 0.27–7.13 μg Fe g −1 was released into seawater, with less efficient release as sediment load increased. Conversely, Si, Mn, and Co exhibited a more constant rate of release, which was less sensitive to sediment load. Dissolved Si release was equivalent to 17% ± 22% of particulate amorphous Si after 1–2 weeks. Dissolved Mn concentrations in most incubations exceeded dissolved Fe concentrations within 1 hr despite labile Mn content being 12‐fold lower than labile Fe content. Our results show the potential for glacier‐derived particles to be a large source of Mn and Co to marine waters and add to the growing evidence that Mn may be the bio‐essential metal most affected by glacier‐associated sources.

10.1029/2024gb008144

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Citations (1)