Taxonomy and species diversity of Holocene pylonioid radiolarians from surface sediments of the northeastern Indian Ocean

Zhang, Lanlan; Suzuki, Noritoshi

doi:10.26879/718

Cited by 11 publications

(6 citation statements)

References 27 publications

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“…are also common in temperate areas (Kamikuri et al 2008;Romine 1985). According to Zhang and Suzuki (2017), our Phorticium spp. and Tetrapyle spp.…”

Section: Relative Abundance Of Abundant Speciesmentioning

confidence: 98%

“…Sample examination continued until at least radiolarians were identified in each sample, or until the sample material was exhausted. The identification followed the nomenclature of Itaki (2009), Matsuzaki et al (2015a), and Zhang and Suzuki (2017) for extant species. For extinct species, we mainly followed the taxonomic nomenclature of Nigrini and Lombari (1984), Motoyama (1996), and Kamikuri (2010).…”

Section: Assemblage Analysismentioning

confidence: 99%

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Paleoceanographic history of the Japan Sea over the last 9.5 million years inferred from radiolarian assemblages (IODP Expedition 346 Sites U1425 and U1430)

Matsuzaki

Itaki

Tada

et al. 2018

Prog Earth Planet Sci

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Previous studies showed that the evolution of the Japan Sea paleoceanography since the Miocene has been influenced by the regional tectonism (e.g., opening/closing of the connecting seaways) and regional/global climate. In the Japan Sea, Expedition 346 of the Integrated Ocean Drilling Program (IODP) retrieved core sediments dating back to the Miocene at two sites (U1425 and U1430). In this study, we reconstruct shallow-to-deep-water hydrography of the Japan Sea during the Mio-Pliocene based on radiolarian assemblages at Sites U1425 and U1430 considering the local tectonism and changes in global/regional climate. Our data suggest that glacioeustatic sea-level changes have probably had an influence on the local paleoceanography between 9.5 and 7.0 Ma. Indeed, warm water probably flowed from the North Pacific into the Japan Sea when sea level was high via shallow central and eastern seaways. In addition, the sill depth of the northern seaway was probably close to 1000 m between 9.5 and 7.8 Ma and had probably allowed inflow of oxygen minimum zone water from the North Pacific to the Japan Sea when sea level was high. In contrast, our data imply that Cycladophora nakasekoi, an endemic species to the Japan Sea, dominated between 9.5 and 7.3 Ma when sea level was low. Our data also suggest a progressive shoaling of the sill for the period since 7.8 Ma and that global climatic events such as such the late Miocene cooling (7.5-5.5 Ma) and the early Pliocene warmth have had a sustained influence on the Japan Sea. During the mid-Pliocene, a deep cooling of the subsurface to intermediate water of the Japan Sea likely occurred because species related to subarctic subsurface to intermediate waters were dominant between 5 and 3.8 Ma. The Northern Hemisphere Glaciation (ca. 3.0-2.7 Ma) and Mid-Pleistocene Transition (1.2-0.8 Ma) have both likely intensified the cooling of the Japan Sea.

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“…are also common in temperate areas (Kamikuri et al 2008;Romine 1985). According to Zhang and Suzuki (2017), our Phorticium spp. and Tetrapyle spp.…”

Section: Relative Abundance Of Abundant Speciesmentioning

confidence: 98%

Section: Assemblage Analysismentioning

confidence: 99%

Paleoceanographic history of the Japan Sea over the last 9.5 million years inferred from radiolarian assemblages (IODP Expedition 346 Sites U1425 and U1430)

Matsuzaki

Itaki

Tada

et al. 2018

Prog Earth Planet Sci

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“…All radiolarians were identified and counted until at least 400 individual tests were identified in each sample, or until the sample material was exhausted (see the Additional file 1). The identification followed the nomenclature of Itaki (2009), Matsuzaki et al (2015a), and Zhang and Suzuki (2017). On average, we counted 435 specimens per slide.…”

Section: Assemblage Analysismentioning

confidence: 99%

“…In the northern ECS (Site U1429), the occurrence of the Tetrapyle circularis/fruticosa group (Fig. 5b) sensu Zhang and Suzuki (2017) was high during each interglacial period (i.e., MISs 1, 5, 7, 9, and 11; Fig. 5).…”

Section: Relative Abundances Of Selected Speciesmentioning

confidence: 99%

Paleoceanographic changes in the Northern East China Sea during the last 400 kyr as inferred from radiolarian assemblages (IODP Site U1429)

Matsuzaki

Itaki

Tada

2019

Prog Earth Planet Sci

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The East China Sea (ECS) is a shallow marginal sea that is sensitive to glacio-eustatic sea-level changes and is influenced by warm oligotrophic water of the Kuroshio Current (KC), the nutrient-rich Taiwan Warm Current, and freshwater discharges from rivers in southern China during the East Asian summer monsoon season. In this area, local paleoceanographic changes for times prior to 40 ka remain poorly studied because of high sediment accumulation rates on the seafloor. During Integrated Ocean Drilling Program Expedition 346, long sediment cores representing the last 400 kyr were retrieved from the northern part of the ECS (Site U1429). In these cores, radiolarians are abundant and well-preserved, thus using the ecological properties of radiolarians, we analyzed how glacio-eustatic sea-level variations have influenced the paleoceanography of the ECS over the last 400 kyr, with a focus on changes in water properties at intermediate depths. Additionally, the summer sea surface temperature (SST) and intermediate water temperature at about 500 m were quantified by means of data on selected radiolarian species. The KC influenced the shallow water at Site U1429 during each interglacial period over the last 400 kyr (marine isotope stages [MISs] 1, 5, 7, 9, and 11), causing a high summer SST (about 27°C), although inflow of the KC into the ECS was probably delayed until after the sea-level maximum of interglacial MIS 1 and MIS 5. During this lag time, ECS shelf water was the dominant influence on the system. During glacial periods (MISs 2-4, 6, and 10), our data suggest that coastal conditions prevailed, probably because of a sea-level drop of more than 90 m. At these times, the summer SST was colder, ca. 20°C. Changes in the relative abundance of Cycladophora davisiana indicate that the most significant changes in the bottom water occurred during MIS 6, when the bottom water likely became poorer in oxygen. An increase in the shallow-water primary productivity during MIS 7 and MIS 6 was probably the key factor causing the oxygen-poor conditions.

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“…An extensive overview of the existing Neogene to Quaternary literature was used for the taxonomy and identification of each class, and to define as accurately as possible our assemblages and the observed taxa (including Ling and Anikouchine, 1967;Nigrini and Moore, 1979;Nigrini and Lombari, 1984;Boltovskoy and Jankilevich, 1985;Caulet and Nigrini, 1988;Takahashi, 1991;Abelmann, 1992;Boltovskoy, 1998Boltovskoy, , 1999Sharma et al, 1999;Nigrini and Sanfilippo, 2001;Itaki et al, 2003;Lazarus et al, 2005;Kamikuri et al, 2009;Zhang et al, 2009;Matsuzaki et al, 2015;Motoyama et al, 2016;Boltovskoy et al, 2017;Matsuoka, 2017;Zhang and Suzuki, 2017;Sandoval, 2018). Synonymies were also taken into account, especially regarding the work of Boltovskoy (1998Boltovskoy ( , 1999.…”

Section: Description Of the Databasementioning

confidence: 99%

A new automated radiolarian image acquisition, stacking, processing, segmentation, and identification workflow

Tetard¹,

Marchant²,

Cortese³

et al. 2020

Preprint

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Abstract. Identification of microfossils is usually done by expert taxonomists and requires time and a significant amount of systematic knowledge developed over many years. These studies require manual identification of numerous specimens in many samples under a microscope, which is very tedious and time consuming. Furthermore, identification may differ between operators, biasing reproducibility. Recent technological advances in image acquisition, processing, and recognition now enable automated procedures for this process, from microscope image acquisition to taxonomic identification. A new workflow was developed for automated radiolarian image acquisition, stacking, processing, segmentation, and identification. The protocol includes a newly proposed methodology for preparing radiolarian microscopic slides. We mount 8 samples per slide, using a recently developed 3D-printed decanter that enable the random and uniform settling of particles, and minimise the loss of material. Once ready, slides are automatically imaged using a transmitted light microscope. About 4000 specimens per slide (500 per sample) are captured in digital images which include stacking techniques to improve their focus and sharpness. Automated image processing and segmentation is then performed using a custom plugin developed for the ImageJ software. Each individual radiolarian image is automatically classified by a convolutional neural network (CNN) trained on a radiolarian database (currently 17,065 images, corresponding to 112 classes) using the software, ParticleTrieur. The trained CNN has an overall accuracy of about 90 %. The whole procedure, including the image acquisition, stacking, processing, segmentation and recognition, is entirely automated via a LabVIEW interface, and takes approximately 1 hour per sample. Census data count and classified radiolarian images are then automatically exported and saved. This new workflow paves the way for the analysis of long-term, radiolarian-based palaeoclimatic records from siliceous remains-bearing samples.

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Taxonomy and species diversity of Holocene pylonioid radiolarians from surface sediments of the northeastern Indian Ocean

Cited by 11 publications

References 27 publications

Paleoceanographic history of the Japan Sea over the last 9.5 million years inferred from radiolarian assemblages (IODP Expedition 346 Sites U1425 and U1430)

Paleoceanographic history of the Japan Sea over the last 9.5 million years inferred from radiolarian assemblages (IODP Expedition 346 Sites U1425 and U1430)

Paleoceanographic changes in the Northern East China Sea during the last 400 kyr as inferred from radiolarian assemblages (IODP Site U1429)

A new automated radiolarian image acquisition, stacking, processing, segmentation, and identification workflow

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