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2 results on '"Kenneth Neil Mertens"'

1. Dinoflagellate cysts and benthic foraminifera from surface sediments of Svalbard fjords and shelves as paleoenvironmental indicators

Author

Maciej M. Telesiński, Vera Pospelova, Kenneth Neil Mertens, Małgorzata Kucharska, and Marek Zajączkowski

Subjects
North Atlantic, Nordic Seas, Sea ice, Primary productivity, Fjords, Sediments, Oceanography, GC1-1581
Abstract

Due to the Arctic amplification effect, the Svalbard archipelago is an important area for studying ongoing environmental changes. However, its marine ecosystem is extremely complex. In this study, we analyze modern assemblages of dinoflagellate cysts (dinocysts) and benthic foraminifera from surface sediment samples around Svalbard. We use multivariate statistical analyses to examine relationships between environmental conditions (summer and winter sea surface temperature and salinity, sea-ice cover, etc.) and both microfossil groups to evaluate their use as proxies for reconstructions of the marine environment in the region. Our results show that the most important factor controlling the environment around Svalbard is the Atlantic Water which mostly impacts the western coast, but its influence reaches as far as the eastern coast of Nordaustlandet. However, on a local scale, such factors as the sea-ice cover, the presence of tidewater glaciers, or even the morphology and hydrology of fjords become increasingly important. We found that two dinocyst species, cysts of Polarella glacialis and Echinidinium karaense, can be considered regional winter drift ice indicators. The relationships between environmental parameters and benthic foraminiferal assemblages are much more difficult to interpret. Although statistical analysis shows a correlation of benthic foraminiferal species with various environmental parameters, this correlation might be somewhat coincidental and caused by other factors not analyzed in this study. Nevertheless, the use of two complementary microfossil groups as (paleo)environmental indicators can provide a more comprehensive picture of the environmental conditions.

Published
2023
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2. Pentaplacodinium saltonense gen. et sp. nov. (Dinophyceae) and its relationship to the cyst-defined genus Operculodinium and yessotoxin-producing Protoceratium reticulatum

Author

Vera Pospelova, Andrea Highfield, Gwenael Bilien, Marianne Ellegaard, André Rochon, Grant C. Pitcher, Martin J. Head, Maya C. Pfaff, Karl B. Andree, Zhen Fei Lim, Kazuhiko Koike, Kenneth Neil Mertens, Kazumi Matsuoka, Aika Yamaguchi, Yoshihito Takano, Abdulrahman Al-Muftah, Mona Hoppenrath, Elisabeth Nézan, Margarita Fernandez, Haifeng Gu, Po Teen Lim, Declan C. Schroeder, M. Consuelo Carbonell-Moore, Yuri B. Okolodkov, Chui Pin Leaw, Producció Animal, Aigües Marines i Continentals, and Aqüicultura

Subjects
0106 biological sciences, 010506 paleontology, Genes, Protozoan, Zoology, Precingular plates, Plant Science, Aquatic Science, 01 natural sciences, DNA, Ribosomal, California, Monophyly, Intergenic region, DNA, Algal, Genus, Protoceratium, Gonyaulax, Ribosomal DNA, Phylogeny, 0105 earth and related environmental sciences, biology, 010604 marine biology & hydrobiology, Cribroperidinioideae, Operculodinium, Dinoflagellate, Sequence Analysis, DNA, DNA, Protozoan, biology.organism_classification, Ceratocorys, Dinoflagellida, Microscopy, Electron, Scanning, Taxonomy (biology), Pentaplacodinium, Salton Sea, Dinophyceae
Abstract

Strains of a dinoflagellate from the Salton Sea, previously identified as Protoceratium reticulatum and yessotoxin producing, have been reexamined morphologically and genetically and Pentaplacodinium saltonense n. gen. et sp. is erected to accommodate this species. Pentaplacodinium saltonense differs from Protoceratium reticulatum (Claparède et Lachmann 1859) Bütschli 1885 in the number of precingular plates (five vs. six), cingular displacement (two widths vs. one), and distinct cyst morphology. Incubation experiments (excystment and encystment) show that the resting cyst of Pentaplacodinium saltonense is morphologically most similar to the cyst-defined species Operculodinium israelianum (Rossignol, 1962) Wall (1967) and O. psilatum Wall (1967). Collections of comparative material from around the globe (including Protoceratium reticulatum and the genus Ceratocorys) and single cell PCR were used to clarify molecular phylogenies. Variable regions in the LSU (three new sequences), SSU (12 new sequences) and intergenic ITS 1–2 (14 new sequences) were obtained. These show that Pentaplacodinium saltonense and Protoceratium reticulatum form two distinct clades. Pentaplacodinium saltonense forms a monophyletic clade with several unidentified strains from Malaysia. LSU and SSU rDNA sequences of three species of Ceratocorys (C. armata, C. gourreti, C. horrida) from the Mediterranean and several other unidentified strains from Malaysia form a well-supported sister clade. The unique phylogenetic position of an unidentified strain from Hawaii is also documented and requires further examination. In addition, based on the V9 SSU topology (bootstrap values >80%), specimens from Elands Bay (South Africa), originally described as Gonyaulax grindleyi by Reinecke (1967), cluster with Protoceratium reticulatum. The known range of Pentaplacodinium saltonense is tropical to subtropical, and its cyst is recorded as a fossil in upper Cenozoic sediments. Protoceratium reticulatum and Pentaplacodinium saltonense seem to inhabit different niches: motile stages of these dinoflagellates have not been found in the same plankton sample. info:eu-repo/semantics/acceptedVersion

Published
2017

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