Distribution and ecology of the Globigerinoides ruber — Globigerinoides elongatus morphotypes in the Azores region during the late Pleistocene-Holocene

Bonfardeci, Alessandro; Caruso, Antonio; Bartolini, Annachiara; Bassinot, Franck; Blanc-Valleron, Marie-Madeleine

doi:10.1016/j.palaeo.2017.11.052

Cited by 14 publications

(17 citation statements)

References 65 publications

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“…These findings suggest that growth and calcification are affected in different ways. Globigerinoides ruber has significant morphological variability, and morphotypes are known to have differing ecological preferences (Bonfardeci et al, ; Steinke et al, ). While the narrowly defined sensu stricto morphotypes were picked (see section ), there is still some morphological variation within the specimens, which may impact the overall volume of the specimen analyzed.…”

Section: Discussionmentioning

confidence: 99%

Planktic Foraminiferal Test Size and Weight Response to the Late Pliocene Environment

Todd

Schmidt

Robinson

et al. 2020

Paleoceanog and Paleoclimatol

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Atmospheric carbon dioxide (pCO 2 atm ) is impacting the ocean and marine organisms directly via changes in carbonate chemistry and indirectly via a range of changes in physical parameters most dominantly temperature. To assess potential impacts of climate change on carbonate production in the open ocean, we measured size and weight of planktic foraminifers during the late Pliocene at pCO 2 atm concentrations comparable to today and global temperatures 2 to 3°C warmer. Size of all foraminifers was measured at Atlantic Ocean Deep Sea Drilling Project (DSDP) Site 610, Ocean Drilling Program (ODP) Site 999, and Integrated Ocean Drilling Program (IODP) Site U1313. Test size was smaller during the Pliocene than in modern assemblages under the same environmental conditions. During the cold marine isotope stage (MIS) M2, size increased at Site 999, potentially linked to intensified stratification of the surface ocean in response to the closure of the Central American Seaway. At Site U1313, test size tracks the warming throughout the late Pliocene. Size-normalized weight (SNW) of Globigerina bulloides at Site U1313 decreased during warmer temperature intervals. SNW of Globigerinoides ruber (white) at Site 999 displays high-frequency variability not correlated to temperature. Yet during the glacial period within MIS M2, test weight was higher during higher temperatures. Our results support studies in the modern ocean, which challenge the view that carbonate chemistry is the primary driver for calcification. To better understand processes driving changes in SNW, computer tomography was used to quantify calcite to volume ratios. During interglacial periods, lower calcite volume but higher test volume suggests less suitable conditions for calcification. As this signal is not evident in SNW, subtle changes in calcification might not be observed by the weight-based method.Plain Language Summary Calcium carbonate shell-producing organisms in the oceans are in danger of losing the ability to build shells because oceans are becoming warmer and more acidic from absorbing the excess carbon dioxide in the atmosphere. Here we measure the size and weight of microscopic plankton shells during a past climate interval about three million years ago when the atmospheric carbon dioxide level was similar to today. Studying this time interval allows us to quantify impacts of a warmer more acidic ocean on the ability of plankton in the ocean to produce carbonate. During this interval, temperature fluctuated, and local environmental conditions changed in response to the emergence of the Isthmus of Panama. We show here that both size and weight react to global and local drivers, which include but are not limited to temperature.

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Section: Discussionmentioning

confidence: 99%

Planktic Foraminiferal Test Size and Weight Response to the Late Pliocene Environment

Todd

Schmidt

Robinson

et al. 2020

Paleoceanog and Paleoclimatol

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“…elongatus in Mg/Ca composition of the shell. Studies conducted in the Gulf of Mexico [10,21] and in the central North Atlantic [67] showed similar absence of oxygen isotopic offsets between the morphospecies and argued that the difference in habitat, seasonal and calcifying depth is not systematic. Downcore analyses of Mg/Ca ratios from the southwest Pacific [15,20] showed that the difference between the two morphospecies was not stable though time and varied between 0 and 2°C in temperature space.…”

Section: Discussionmentioning

confidence: 99%

Genetic and morphological divergence in the warm-water planktonic foraminifera genus Globigerinoides

et al. 2019

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The planktonic foraminifera genus Globigerinoides provides a prime example of a species-rich genus in which genetic and morphological divergence are uncorrelated. To shed light on the evolutionary processes that lead to the present-day diversity of Globigerinoides, we investigated the genetic, ecological and morphological divergence of its constituent species. We assembled a global collection of single-cell barcode sequences and show that the genus consists of eight distinct genetic types organized in five extant morphospecies. Based on morphological evidence, we reassign the species Globoturborotalita tenella to Globigerinoides and amend Globigerinoides ruber by formally proposing two new subspecies, G. ruber albus n.subsp. and G. ruber ruber in order to express their subspecies level distinction and to replace the informal G. ruber “white” and G. ruber “pink”, respectively. The genetic types within G. ruber and Globigerinoides elongatus show a combination of endemism and coexistence, with little evidence for ecological differentiation. CT-scanning and ontogeny analysis reveal that the diagnostic differences in adult morphologies could be explained by alterations of the ontogenetic trajectories towards final (reproductive) size. This indicates that heterochrony may have caused the observed decoupling between genetic and morphological diversification within the genus. We find little evidence for environmental forcing of either the genetic or the morphological diversification, which allude to biotic interactions such as symbiosis, as the driver of speciation in Globigerinoides.

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“…Classifiers who were trained prior to the reinstatement would thus likely classify G. elongatus individuals as G. ruber . In this particular case, the problem is also amplified by the ambiguity of the line between G. elongatus and G. ruber, as they form an intergrading species plexus (Bonfardeci et al, ). Furthermore, the more elongate spiral on the dorsal side that is often used to diagnose G. elongatus versus G. ruber is not always visible in images taken from the umbilical side, as is the case with the YPM and Buckley images used here.…”

Section: Discussionmentioning

confidence: 99%

Endless Forams: >34,000 Modern Planktonic Foraminiferal Images for Taxonomic Training and Automated Species Recognition Using Convolutional Neural Networks

Hsiang

Brombacher

Rillo

et al. 2019

Paleoceanog and Paleoclimatol

103

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Planktonic foraminiferal species identification is central to many paleoceanographic studies, from selecting species for geochemical research to elucidating the biotic dynamics of microfossil communities relevant to physical oceanographic processes and interconnected phenomena such as climate change. However, few resources exist to train students in the difficult task of discerning amongst closely related species, resulting in diverging taxonomic schools that differ in species concepts and boundaries. This problem is exacerbated by the limited number of taxonomic experts. Here we document our initial progress toward removing these confounding and/or rate-limiting factors by generating the first extensive image library of modern planktonic foraminifera, providing digital taxonomic training tools and resources, and automating species-level taxonomic identification of planktonic foraminifera via machine learning using convolution neural networks. Experts identified 34,640 images of modern (extant) planktonic foraminifera to the species level. These images are served as species exemplars through the online portal Endless Forams (endlessforams.org) and a taxonomic training portal hosted on the citizen science platform Zooniverse (zooniverse.org/projects/ahsiang/ endless-forams/). A supervised machine learning classifier was then trained with~27,000 images of these identified planktonic foraminifera. The best-performing model provided the correct species name for an image in the validation set 87.4% of the time and included the correct name in its top three guesses 97.7% of the time. Together, these resources provide a rigorous set of training tools in modern planktonic foraminiferal taxonomy and a means of rapidly generating assemblage data via machine learning in future studies for applications such as paleotemperature reconstruction.

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Distribution and ecology of the Globigerinoides ruber — Globigerinoides elongatus morphotypes in the Azores region during the late Pleistocene-Holocene

Cited by 14 publications

References 65 publications

Planktic Foraminiferal Test Size and Weight Response to the Late Pliocene Environment

Planktic Foraminiferal Test Size and Weight Response to the Late Pliocene Environment

Genetic and morphological divergence in the warm-water planktonic foraminifera genus Globigerinoides

Endless Forams: >34,000 Modern Planktonic Foraminiferal Images for Taxonomic Training and Automated Species Recognition Using Convolutional Neural Networks

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