MÃ

Miguel Ãngel Fuertes

Universidad de Salamanca

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Co-Authors

José‐Abel Flores

Weatherford College

Francisco Javier Sierro

Universidad de Salamanca

Andrés S. Rigual‐Hernández

Universidad de Salamanca

Thomas W. Trull

University of Tasmania

Anne-Marie Ballegeer

Universidad de Salamanca

Heather Stoll

ETH Zurich

Fatima F Abrantes

University of Algarve

Ruth Eriksen

University of Tasmania

Lisa C. Northcote

National Institute of Water and Atmospheric Research

Diana M. Davies

Australian Antarctic Division

Cooperative Institutions

Universidad de Salamanca

International Ocean Discovery Program

University of Bremen

National Institute of Water and Atmospheric Research

Universidad de Oviedo

Universidade de Santiago de Compostela

ETH Zurich

Texas A&M University

Discovery Place

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

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Calcification and distribution of extant coccolithophores across the Drake Passage during late austral summer 2016

Mariem Saavedra‐Pellitero Karl‐Heinz Baumann Miguel Ãngel Fuertes Hartmut Schulz Yann Marcon

Abstract. Coccolithophores are globally distributed microscopic marine algae that exert a major influence on the global carbon cycle through calcification and primary productivity. There is recent interest in coccolithophore polar communities, however field observations regarding their biogeographic distribution are scarce for the Southern Ocean. This study documents the latitudinal variability in the coccolithophore assemblage composition and the coccolith mass variation of the ecologically dominant Emiliania huxleyi across the Drake Passage. Ninety-six water samples were taken between 10 and 150 m water depth from 18 stations during POLARSTERN Expedition PS97 (February–April, 2016). A minimum of 200 coccospheres per sample were classified in scanning electron microscope and coccolith mass was estimated with light microscopy, using the C-Calcita software. We find that coccolithophore abundance and diversity decrease southwards marking different oceanographic fronts as ecological boundaries. We characterize three zones: (1) the Chilean margin, where E. huxleyi type A (normal and overcalcified) and type R are present; (2) the Subantarctic Zone (SAZ), where E. huxleyi reaches maximum values of 212.5×103cells/L and types B/C, C, O are dominant. (3) The Polar Front Zone (PFZ), where E. huxleyi types B/C and C dominate. We link the decreasing trend in E. huxleyi coccolith mass to the poleward latitudinal succesion from type A to type B group. Remarkably, we find that coccolith mass is strongly anticorrelated to total alkalinity, total CO2, bicarbonate ion and pH. We speculate that low temperatures are a greater limiting factor than carbonate chemistry in the Southern Ocean. However, further in situ oceanographical data is needed to verify the proposed relationships. We hypothesize that assemblage composition and calcification modes of E. huxleyi in the Drake Passage will be strongly influenced by the ongoing climate change.

Coccolith

Emiliania huxleyi

Coccolithophore

Polar front

Ocean Acidification

10.5194/bg-2019-186

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Citations (2)

Southern Ocean and Southern African Monsoon Forcing of the Subtropical Indian Ocean Early Pliocene “Biogenic Bloom”

Paleoceanography and Paleoclimatology (2024)

D. Tangunan José‐Abel Flores Leah J. LeVay F.J. Jiménez-Espejo Jason J. Coenen

Abstract The Pliocene epoch emerges as a pivotal juncture in Earth's climatic evolution, characterized by pronounced warmth and elevated atmospheric carbon dioxide compared to contemporary levels. While the broader climatic context of the Pliocene has garnered attention, there remains an outstanding gap in detailed paleoclimate reconstructions of the early Pliocene, a new potential target for data‐model intercomparison. Addressing this, we investigate the drivers of the early Pliocene “Biogenic Bloom” and implications for nutrient dynamics and climate. By analyzing high‐resolution biotic assemblage and geochemical records from the Agulhas Plateau, southwestern Indian Ocean (International Ocean Discovery Program, IODP Site U1475), we aim to elucidate the forcing and feedback mechanisms driving the early Pliocene marine ecosystems. We identify a distinct shift in coccolithophore assemblages at ∼4.6 million years ago, characterized by a notable change in dominance between the larger and smaller Reticulofenestra and high abundances of Noelaerhabdaceae < 5 µm. Our findings confirm the adaptive strategies of coccolithophore communities to prevailing environmental conditions, underscoring their evolutionary resilience by producing smaller coccoliths while increasing their abundances in a nutrient‐replete ocean. Surface water dynamics, particularly the subtropical front migration and expansion of Southern Ocean waters, in combination with the southern African monsoon variability, emerge as key drivers of phytoplankton productivity during the early Pliocene. We posit that a weakened biological carbon pump, due to increased phytoplankton production driven by intense ocean circulation and mixing during the early Pliocene, served as a potential precursor to the subsequent middle Pliocene abrupt climate extremes.

Bloom

Forcing (mathematics)

Subtropical front

East Asian Monsoon

10.1029/2024pa004927

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An empirical method for absolute calibration of coccolith thickness

Saúl González‐Lemos José Guitián Miguel Ãngel Fuertes José‐Abel Flores Heather Stoll

Abstract. As major calcifiers in the open ocean, coccolithophores play a key role in the marine carbon cycle. Because they may be sensitive to changing CO2 and ocean acidification, there is significant interest in quantifying past and present variations in their cellular calcification by quantifying the thickness of the coccoliths or calcite plates that cover their cells. Polarized light microscopy has emerged as a key tool for quantifying the thickness of these calcite plates, but the reproducibility and accuracy of such determinations has been limited by the absence of suitable calibration materials in the thickness range of coccoliths (0–4 microns). Here, we describe the fabrication of a calcite wedge with a constant slope over 15 this thickness range, and the independent determination of calcite thickness along the wedge profile. We show how the calcite wedge provides more robust calibrations in the 0 to 1.55 μm range than previous approaches using rhabdoliths. We show the particular advantages of the calcite wedge approach for developing equations to relate thickness to the interference colors that arise in calcite in the thickness range between 1.55 and 4 μm. The calcite wedge approach can be applied to develop equations relevant to the particular light spectra and intensity of any polarized light microscope system and could significantly improve within and inter-laboratory data comparability.

Coccolith

Wedge (geometry)

Coccolithophore

10.5194/bg-2017-249

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Citations (11)

Improvement on Social Representation of Climate Change through a Knowledge-Based MOOC in Spanish

Sustainability (2019)

Enzo Ferrari Anne-Marie Ballegeer Miguel Ãngel Fuertes Pablo Herrero Teijón Laura Delgado

Climate Change is the most important threat to our society and all species on Earth. Large alterations in the climate are affecting every aspect of our society and in order to limit this impact we must decarbonize the economy before 2050. Although science presents solid evidence on the magnitude of the problem and outlines precisely the consequences, people do not act accordingly and do not consider this issue a priority for their survival. The reason behind this paradox might be a non-appropriate Social Representation of Climate Change in society as the Social Representation conditions and forms the response of the society. In this paper, we extend previous investigations of how this Social Representation is formed in order to find ways to improve it through a Massive Online Open Course on the Science of Climate Change. Using a validated questionnaire, we investigated the knowledge dimension of the Social Representation of Climate Change in a group of students of a MOOC on Climate Change. A pre- and posttest revealed general improvements in all the categories that were considered in this study. A detailed analysis showed different degrees of improvement for different groups, providing new insights in the efficiency of knowledge-based online courses. Well designed Massive Online Open Courses, based on scientific evidence, targeted to the general public might improve the Social Representation of Climate Change, which may in turn trigger awareness and an effective mobilization to address this important and urgent topic.

Representation

Social representation

10.3390/su11226317

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Citations (21)

How Long Has It Taken for the Physical Landscape to Form? Conceptions of Spanish Pre-Service Teachers

Education Sciences (2020)

Alejandro Gómez Gonçalves Diego Corrochano Miguel Ãngel Fuertes Anne-Marie Ballegeer

This paper analyses the conceptions of a group of students about geological time and its relation to physical landscape formation, focusing on the frequency and rate of a number of geological processes that have shaped our planet over time and that are involved in the formation of the current relief. Data were collected by means of a questionnaire that was administered to 199 university students from a Spanish public university. A total of 185 of them were pre-service teachers and 14 were geology students. Results demonstrated that pre-service teachers had trouble correctly answering questions about the current relief, but especially those questions related to landscapes throughout the history of Earth. Data analysis was done, taking into account pre-university students’ tuition, and results showed that those who had taken a high school branch of sciences and technology obtained better results than those who had taken a humanities and social sciences branch. These latter also obtained better results than those who had taken arts as a high school branch. Furthermore, pre-service teachers had difficulties mastering mid-time magnitudes, which ended up making it difficult for them to understand how the physical landscapes were formed. Finally, from the obtained results, some curricula implications are discussed.

Physical science

10.3390/educsci10120373

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Citations (4)

Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic Zone

Andrés S. Rigual‐Hernández José‐Abel Flores Francisco Javier Sierro Miguel Ãngel Fuertes Lluïsa Cros

Abstract. The Southern Ocean is experiencing rapid and relentless change in its physical and biogeochemical properties. The rate of warming of the Antarctic Circumpolar Current exceeds that of the global ocean, and the enhanced uptake of carbon dioxide is causing basin-wide ocean acidification. Observational data suggest that these changes are influencing the distribution and composition of pelagic plankton communities. Long-term and annual field observations on key environmental variables and organisms are a critical basis for predicting changes in Southern Ocean ecosystems. These observations are particularly needed, since high-latitude systems have been projected to experience the most severe impacts of ocean acidification and invasions of allochthonous species. Coccolithophores are the most prolific calcium carbonate producing phytoplankton group, playing an important role in Southern Ocean biogeochemical cycles. Satellite imagery has revealed elevated particulate inorganic carbon concentrations near the major circumpolar fronts of the Southern Ocean, that can be attributed to the coccolithophore Emiliania huxleyi. Recent studies have suggested changes during the last decades in the distribution and abundance of Southern Ocean coccolithophores. However, due to limited field observations, the distribution, diversity and state of coccolithophore populations in the Southern Ocean remain poorly characterized. We report here on seasonal variations in the abundance and composition of coccolithophore assemblages collected by two moored sediment traps deployed in the deep ocean (~ 2000 and 3700 m) in the Australian sector of the Antarctic Zone for one year in 2001–02. Additionally, seasonal changes in coccolith weights of E. huxleyi populations were estimated using circularly polarized micrographs analysed with C-Calcita software. Our findings indicate that (1) coccolithophore sinking assemblages were nearly monospecific for Emiliania huxleyi morphotype B/C in the Antarctic Zone waters in 2001–2002; (2) coccolith assemblages experienced weight and length reduction during the summer months; (3) the estimated annual coccolith weight of E. huxleyi at both sediment trap depths (2.11 ± 0.96 and 2.13 ± 0.90 pg at 2000 m and 3700 m) was consistent with previous studies for morphotype B/C in other Southern Ocean settings; (4) coccolithophores accounted for approximately 2–5 % of the annual, deep-ocean CaCO3 flux. Our results are the first annual record of coccolithophore abundance, composition and degree of calcification in the Antarctic Zone. They provide a baseline against which to monitor coccolithophorid responses to changes in environmental conditions expected for this region in coming decades.

Coccolithophore

Emiliania huxleyi

Biogeochemical Cycle

Coccolith

Circumpolar star

Ocean Acidification

10.5194/bg-2017-523

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Citations (8)

Variation in calcification of Reticulofenestra coccoliths over the Oligocene–Early Miocene

Biogeosciences (2022)

José Guitián Miguel Ãngel Fuertes José‐Abel Flores Iván Hernández‐Almeida Heather Stoll

Abstract. Coccolithophores are calcifying marine phytoplankton whose intracellularly produced calcite plates, coccoliths, have been the dominant source of calcium carbonate in open-ocean settings since the Cretaceous. An open question is whether their calcification has been affected by changing environmental conditions over geological timescales such as variations in the ocean carbon system. Previous methods using circular polarized light microscopy allowed for only the thickness of small coccoliths thinner than 1.5 µm to be quantified, but prior to the Pliocene, a significant fraction of the coccoliths exceeded this thickness and have not been quantifiable. Here, we implement a new approach for calibration of circular polarized light microscopy enabling us to quantify coccoliths which feature calcite up to 3 µm thick. We apply this technique to evaluate the evolution of calcification in the Reticulofenestra from the early Oligocene to Early Miocene in exceptionally well-preserved sediments from the Newfoundland margin. Through this time interval, coccolith thickness and the scale-invariant shape factor kse vary by about 20 % around the mean thickness of 0.37 µm and mean kse of 0.16. Lower shape factors characterize samples with a higher relative abundance of dissolution-resistant nannoliths, suggesting that dissolution may contribute to thinning of placoliths. We therefore define temporal trends in calcification only in samples in which the assemblage suggests minimal dissolution. The lowest kse characterizes the middle Oligocene, and the highest kse around 18 Ma is in the Early Miocene. High ocean dissolved inorganic carbon (DIC) concentrations have been proposed for this period of the Miocene and may be one factor contributing to high coccolith kse.

Coccolith

paleoceanography

Emiliania huxleyi

10.5194/bg-19-5007-2022

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Citations (9)

Coccolith mass variability and contribution to carbonate production of coccolithophores in the Southern Ocean: modern versus fossil assemblages

AGUFM (2018)

Andrés S. Rigual‐Hernández Thomas W. Trull José‐Abel Flores SD Nodder Francisco Javier Sierro

Coccolith

Ocean Acidification

Source

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Citations (0)

Coccolithophore paleoproductivity since the Last Glacial Maximum in the Atlantic Ocean: Relationship with calcification and preservation variability

Quaternary International (2022)

Carmen Argenio José‐Abel Flores Miguel Ãngel Fuertes Barbara Balestra Filomena Ornella Amore

Coccolith

Stadial

Coccolithophore

Last Glacial Maximum

Emiliania huxleyi

10.1016/j.quaint.2022.10.010

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Citations (1)

Variation in calcification of Reticulofenestra coccoliths over the Oligocene-Early Miocene

José Guitián Miguel Ãngel Fuertes José‐Abel Flores Iván Hernández‐Almeida Heather Stoll

Abstract. Coccolithophores are calcifying marine phytoplankton whose intracellularly produced calcite plates, or coccoliths, have been the dominant source of calcium carbonate in open ocean settings since the Cretaceous. An open question is whether their calcification has been affected by variation in environmental parameters such as the ocean carbon system over geological timescales. Previous methods using circular polarized light microscopy allowed only the thickness of small coccoliths thinner than 1.5 microns to be quantified but prior to the Pliocene, a significant fraction of the coccoliths exceed this thickness and have not been quantifiable. Here, we implement a new approach for calibration of circular polarized light microscopy enabling us to quantify coccoliths which feature calcite up to 3 microns thick. We apply this technique to evaluate the evolution of calcification in the Reticulofenestra from the Early Oligocene to Early Miocene in exceptionally well-preserved sediments from the Newfoundland margin. Through this time interval, coccolith thickness and the scale-invariant shape factor kse vary by about 20 % around the mean thickness of 0.37 µm and mean kse of 0.16. Lower shape factors characterize samples with higher relative abundance of dissolution-resistant nannoliths, suggesting that dissolution may contribute to thinning of placoliths. We therefore define temporal trends in calcification only in samples in which the assemblage suggests minimal dissolution. Lowest kse characterizes the Middle Oligocene, and highest kse around 18 Ma in the Early Miocene. High ocean DIC concentrations have been proposed for this period of the Miocene, and may be one factor contributing to high coccolith kse.

Coccolith

Emiliania huxleyi

paleoceanography

10.5194/bg-2022-66

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Citations (4)

Miguel Ãngel Fuertes

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Miguel Ãngel Fuertes