REVUE DE MICROPALEONTOLOGIE最新文献

{"title":"Growth pattern of the siliceous skeletons of living Spumellaria (Radiolaria) from the Kuroshio Current, offshore southwestern Shikoku Island, Japan","authors":"Rie S. Hori ,&nbsp;Takenobu Shinki ,&nbsp;Akihiro Iwakiri ,&nbsp;Atsushi Matsuoka ,&nbsp;Noritoshi Suzuki ,&nbsp;Kaoru Ogane ,&nbsp;Akihiro Tuji","doi":"10.1016/j.revmic.2021.100504","DOIUrl":"10.1016/j.revmic.2021.100504","url":null,"abstract":"<div><p>Experimental culture<span> studies of living radiolarians experience many difficulties because radiolarians are too sensitive to be maintained alive in artificial conditions. We here developed an improved experimental protocol in order to detect newly-formed parts of the polycystine radiolarian skeletons after they were labeled with fluorescent markers. Living samples were collected from surface seawater of the Kuroshio Current offshore from Kashiwajima Island, Kochi Prefecture on the island of Shikoku, Japan. The taxonomic composition of the Kashiwajima radiolarian samples varied markedly across the seasons and sampling sites. Spumellaria were usually abundant in samples collected near Kashiwajima, and had high diversity in shell morphology. Here, we performed experimental studies on living spumellarian radiolarians to clarify their siliceous skeletogenesis. Our culture-based research on spumellarians provided the following results.</span></p><p>(A) The pattern of silica deposition on the skeleton of <em>Spongaster tetras tetras</em> varies depending on the growth stage. Three ontogenetic stages were identified: (1) young, (2) progressively-growing and (3) fully-grown. Furthermore, novel varied types of skeletal growth modes were determined as follows: (i) rapid growth on the outermost shell with enlargement of shell size and (ii) internal deposition on skeletal components without change in shell size. From measurements of the growth rate of cultured radiolarians, it is assumed that <em>S. tetras tetras</em> cell has at least a month-long life cycle.</p><p>(B) Spherical spumellarians have their own shell-forming strategy that permits additional silicogenesis while maintaining the taxonomically-specific shape of their shell; the meshwork of their shell surface consists of polygonal-shaped pore-frames formed by heterogeneous patterns of added silica.</p><p>Our direct observation with fluorescence markers detected a skeletogenesis process of <em>Haliommilla capillacea</em><span> possessing a fragile spherical shell. We thus confirm the bridge-growth hypothesis for morphogenesis of the polygonal frame as proposed in previous studies. </span><em>Spongosphaera streptacantha</em><span>, having extremely long spines, exhibited a special growth pattern of spine elongation in a centrifugal direction, without a change in width. This was achieved by a particular temporal pattern of silicification characterized by an alternating pattern of patchy addition of new silica on the entire part of each blade from the base to the tip. Moreover, a thin layer of new silica was added by a flowing deposition along the edge of the spine. Based on these culture-based studies using living radiolarians, we conclude that Spumellaria control and maintain a particular shell shape by regulating where silicification takes place on the skeleton, particularly depending on the growth stage.</span></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2021.100504","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128624086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Middle to Late Paleocene larger benthic foraminifera from the Sirt Basin (Libya)","authors":"Aleš Vršič ,&nbsp;Elżbieta Machaniec ,&nbsp;Hans-Jürgen Gawlick","doi":"10.1016/j.revmic.2021.100481","DOIUrl":"10.1016/j.revmic.2021.100481","url":null,"abstract":"<div><p>The Sirt Basin of Libya hosts significant hydrocarbon reservoirs in Paleocene shallow-marine carbonates (Upper Sabil Formation) with abundant larger benthic foraminifera. Benthic foraminifera proved to be an essential biostratigraphic tool for precise biostratigraphic dating of these carbonate platform/ramp deposits. A detailed systematic description of the Middle to Late Paleocene larger benthic foraminifera from the Sirt Basin is presented, which refines the biostratigraphic age of the Paleogene shallow-marine carbonates. Eight taxa are identified at a species level. Among them, <em>Ranikothalia solimani</em> is the most important taxon for the correlation of the Upper Sabil Formation. The taxa <em>Miscellanea yvettae</em>, <em>Miscellanites primitivus,</em> and <em>Glomalveolina primaeva</em> with co-occurrence of orthophragminid foraminifera constrain the age of the Upper Sabil Formation as Middle to Late Paleocene (Selandian-Early Thanetian).</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2021.100481","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134452741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstruction of oceanographic and environmental conditions in the eastern Mediterranean (Kottafi Hill section, Cyprus Island) during the middle Miocene Climate Transition","authors":"M. Athanasiou ,&nbsp;M.V. Triantaphyllou ,&nbsp;M.D. Dimiza ,&nbsp;A. Gogou ,&nbsp;I. Panagiotopoulos ,&nbsp;A. Arabas ,&nbsp;E. Skampa ,&nbsp;K. Kouli ,&nbsp;M. Hatzaki ,&nbsp;E. Tsiolakis","doi":"10.1016/j.revmic.2020.100480","DOIUrl":"https://doi.org/10.1016/j.revmic.2020.100480","url":null,"abstract":"<div><p><span><span>The multi-proxy investigation of the deep-marine Kottafi Hill section (KHS), a part of the carbonate system of the </span>Miocene<span> Pakhna Formation, Cyprus, involved such proxies as calcareous nannofossil analysis, measurements of the oxygen and carbon isotope composition of the planktonic foraminifer </span></span><em>Orbulina universa</em><span><span>, and determination of the pollen and palynomorph contents, revealed the importance of these sedimentary sequences in the assessment of the impact of major global events during the middle Miocene on the regional scale. The KHS spans the 20.89–11.6 Ma time interval, during which eighteen OC-rich </span>siltstone intercalated laminae have been deposited under warm and humid climate at 15.5–11.6 Ma. These layers can be possibly considered as the precursors of sapropelic layers mostly developed in the eastern Mediterranean Basin during Pliocene–Holocene. The global glacial events Mi3a–Mi5, traced by δ</span>¹⁸O planktonic foraminifera records in the KHS, represent the stepwise cooling phase during the middle Miocene Climate Transition.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2020.100480","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91618022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benthic foraminiferal assemblages and biostratigraphy of the Antalo Limestone, Mekelle Basin, Northern Ethiopia","authors":"Damenu Adefris ,&nbsp;M.E. Nton ,&nbsp;O.A. Boboye ,&nbsp;Balemwal Atnafu","doi":"10.1016/j.revmic.2020.100479","DOIUrl":"https://doi.org/10.1016/j.revmic.2020.100479","url":null,"abstract":"<div><p><span>This study focused on the identification, detailed systematic descriptions and stratigraphical distributions of different foraminifera and other species to make the first systematic paleontological analysis, interpret paleoenvironment<span><span> and determine the age of Antalo Limestone of the Mekelle Basin. Fieldwork and section logging, with sample collection at seven outcrop locations, followed by </span>petrography<span> and standard micropaleontological analysis were carried out. Abundant foraminifera fossils<span><span> of 17 species were identified from 42 thin sections and 5 washed samples of marl and shale. The faunal assemblage also comprised dasyclad green algae, </span>calpionellid, brachiopods and stromatoporoids (</span></span></span></span><em>Cladocoropsis mirabilis</em>). The benthic foraminiferal assemblage is represented by 3 species of the order Lituolida (<em>Freixialina planispiralis</em>, <em>Nautiloculina circularis</em> and <em>N</em>. <em>oolithica</em>), 11 species of the order Loftusiida (<em>Alveosepta jaccardi</em>, <em>Choffatella tingitana</em>, <em>Conicokurnubia orbitoliniformis</em>, <em>Everticyclammina virguliana</em>, <em>Kurnubia jurassica</em>, <em>K</em>. <em>morrisi, K</em>. <em>palastiniensis, K</em>. <em>wellingsi</em>, <em>Praekurnubia crusei</em>, <em>Pseudocyclammina lituus</em> and <em>Siphovalvulina variabilis</em>), 2 species of the order Textulariida (<em>Redmondoides lugeoni</em> and <em>Valvulina lugeoni</em>) and 1 species of the order Miliolida (<em>Miliolinella quinquangula</em>). The green algae comprised 3 species of the order Dasycladales (<em>Clypeina jurassica</em>, <em>Salpingoporella annulata</em> and <em>Salpingoporella</em> gr. <em>pygmaea</em>). The calpionellid is represented by 1 species of the order Calpionellidae (<em>Calpionella alpina</em>). The brachiopods comprised 2 species of the orders Rhynchonellida (<em>Somalirhynchia africana</em>) and Terebratulida (<em>Somalithyris bihendulensis</em><span>). Based on the stratigraphical distributions of these benthic foraminifera, dasyclad green algae, calpionellid and brachiopods, three zones namely; </span><em>Kurnubia palastiniensis</em>, <em>Somalirhynchia africana</em>/<em>Somalithyris bihendulensis</em> and <em>Alveosepta jaccardi</em>/<em>Pseudocyclammina lituus</em><span><span><span> have been established, signifying a Callovian<span> – Oxfordian, a Callovian – Early Kimmeridgian<span> and a Kimmeridgian – Tithonian ages respectively. Therefore, a Callovian – Tithonian age has been assigned to the Antalo Limestone. This faunal assemblage indicated a shallow – deep marine environment with normal marine </span></span></span>salinity which has a strong affinity with the faunas of the Middle – Upper Jurassic Peri-Tethyan carbonates, indicating closely related geological evolution. Six benthic foraminiferal morphogroups have been identified, indicating epifaunal – infaunal </span>microhabitats and active deposit-fe","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2020.100479","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91618023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"VSI “Updating Micropaleontology and Stratigraphy in Greece and Eastern Mediterranean” of the Hellenic Committee for Paleontology and Stratigraphy in the honor of Professor Emeritus Michael D. Dermitzakis","authors":"Maria Triantaphyllou,&nbsp;Margarita Dimiza","doi":"10.1016/j.revmic.2021.100484","DOIUrl":"10.1016/j.revmic.2021.100484","url":null,"abstract":"<div><p>The current Special Issue of Revue de Micropaleontologie, entitled “Updating Micropaleontology and Stratigraphy in Greece and Eastern Mediterranean” includes contributions from the T1S1 special Session [conveners Maria Triantaphyllou (NKUA), Dimitris Kostopoulos (AUTH), George Iliopoulos (UPAT)] organized by the Hellenic Committee for Paleontology and Stratigraphy at the 15th Conference of the Geological Society of Greece (May 2019, Athens, Greece).</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2021.100484","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130523473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Micropalaeontological analysis and palaeoenvironmental interpretation of the upper sedimentary sequence of Corinth Marl (Corinth Isthmus, Greece)","authors":"Theodora Tsourou ,&nbsp;Maria V. Triantaphyllou ,&nbsp;Sophia Cheilaris ,&nbsp;Eugenia G. Fatourou ,&nbsp;Ioannis Michailidis ,&nbsp;Anastasios P. Nikitas ,&nbsp;Maria A. Tzortzopoulou ,&nbsp;Margarita Dimiza ,&nbsp;Elizabeth Stathopoulou","doi":"10.1016/j.revmic.2020.100466","DOIUrl":"https://doi.org/10.1016/j.revmic.2020.100466","url":null,"abstract":"<div><p><span>The current study performs a detailed micropalaeontological analysis, in terms of ostracods<span><span>, benthic foraminifera and calcareous </span>nannoplankton<span>, in order to reconstruct the palaeoenvironmental history of the sedimentary sequence<span><span> exposed in the central part of Corinth Isthmus. Twenty one samples from two lateral sections were studied, on both sides of a westwards dipping normal fault at the west end of the central horst, which are part of the same stratigraphical sequence. The calcareous </span>nannofossil analysis provided for the first time dating evidence for the upper Corinth Marl sequence, revealing that Section A (at the footwall block of the fault/the upper part of the Corinth Marl) is attributed to the Early Pleistocene /Calabrian (nannofossil biozone MNN19f) and that Section B (at the hanging wall of the fault) is assigned to the Middle Pleistocene /Chibanian (MNN20). Both parts of the studied sequence not only differentiate in age but bear notably separated species composition of the main ostracod assemblages as well. The combined study of ostracod and benthic foraminiferal microfaunas indicated that at least since Early Pleistocene the Corinth Marl deposits at the central part of Corinth Isthmus corresponded to a shallow, restricted, oligohaline lagoon with </span></span></span></span>salinity alternations expressed as layers enriched in nannofossil content. Towards Middle Pleistocene the lagoon presented increased salinity and signs of shoaling. The studied sequence closes upwards with a bed of Middle Pleistocene age, rich in marine molluscs and corals indicating a radical environmental change: the opening of the lagoon and the establishment of a shallow marine coastal environment.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2020.100466","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91618024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the status of the radiolarian genus Spongoliva Haeckel, 1887 and the description of the genus Spongolivella n. gen","authors":"Paulian Dumitrică","doi":"10.1016/j.revmic.2020.100477","DOIUrl":"https://doi.org/10.1016/j.revmic.2020.100477","url":null,"abstract":"<div><p><span>The author erects a new genus<span> for the Quaternary artiscin radiolarian species </span></span><em>Spongoliva ellipsoides</em> Popofsky 1912. The genus <em>Spongoliva</em> Haeckel 1887 is a <em>nomen dubium</em><span> because none of its six species has been illustrated and, above all, its type species is Eocene in age, an epoch when the artiscins had not yet appeared.</span></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2020.100477","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91657327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A preliminary investigation of Eocene larger benthic foraminifera assemblages from Alpine and molasse-type deposits of the Hellenic peninsula (Greece)","authors":"Vasiliki-Grigoria Dimou ,&nbsp;Olga Koukousioura ,&nbsp;Margarita D. Dimiza ,&nbsp;Maria V. Triantaphyllou ,&nbsp;György Less ,&nbsp;Fotini Pomoni-Papaioannou ,&nbsp;Georgios Syrides","doi":"10.1016/j.revmic.2020.100468","DOIUrl":"https://doi.org/10.1016/j.revmic.2020.100468","url":null,"abstract":"<div><p>Larger Benthic Foraminifera (LBF) from five localities in Greece were studied in order to define the morphological features of various nummulitid forms and to describe the foraminiferal assemblages in different geotectonic environments. The selected sites belong to molasse-type formations in Kirki/Thrace Basin and Vasiliki Trikala/Mesohellenic Trough, and carbonate deposits in Alpine Pindos, Ionian and Tripolis geotectonic units.</p><p><span>Taxonomic studies combined with biometric data, when possible, enabled us to identify different morphotypes. In the molasse-type deposits of Thrace Basin (Kirki Thrace), </span><em>N. perforatus</em> was found along with <em>N. maximus</em> and <em>Assilina exponens</em> suggesting correlation with biozone SBZ 16/17, while in the Mesohellenic Trough deposits (Vasiliki Trikala) the association included <em>N. perforatus</em> group, <em>Operculina gomezi</em> group and <em>Silvestriella tetraedra</em><span><span>, indicating a Bartonian age, SBZ 17-18A. In outcrops found within Pindos unit (Perivoli Grevena) three different assemblages have been observed in the microbreccious olistholiths, suggesting three distinguished deposits forming quasi-continuous succession spanning from early to middle and up to late Eocene. The Ionian unit (Manoliasa Ioannina) presented a mixed redeposited fauna including late Eocene, early </span>Paleogene and planktonic foraminifera clasts. Finally, the Tripolis unit (Dervenakia and Tripolis) association was interpreted as Bartonian in age, defined by the presence of </span><em>Operculina gomezi</em> group and <em>N. perforatus</em> group.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2020.100468","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89997603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Cenomanian–Turonian boundary event in Egypt: Foraminiferal turnover and carbon isotopic change","authors":"Sherif M. El Baz ,&nbsp;Ahmed A. Kassem","doi":"10.1016/j.revmic.2020.100463","DOIUrl":"https://doi.org/10.1016/j.revmic.2020.100463","url":null,"abstract":"<div><p>This study deals with the integration between geochemical data (carbon isotope and, total organic carbon) and foraminiferal turnover to track the Oceanic Anoxic Event 2 (OAE2) from the OCT-A8st1 well, which located in October field, central part of Gulf of Suez, Egypt. The studied well is subdivided into two formations, namely the Galala (Early–Late Cenomanian) and Abu Qada (Late Cenomanian–Early Turonian). Concerning the foraminiferal assemblage, agglutinated foraminifera dominate the Galala Formation, while planktonic taxa only occur within a few levels in the Abu Qada Formation. Due to the absence of keeled planktonic forms, the biostratigraphic framework is established on the integration between benthonic and planktonic foraminifera. Three biozones are recognized, including <em>Thomasinella aegyptia–Merlingina cretacea</em> Interval Zone (Early–Middle Cenomanian), <em>Thomasinella fragmentaria–Praebulimina aspera</em> Interval Zone (Middle–Late Cenomanian), and <em>Whiteinella archaeocretacea</em> Taxon Range Zone (Late Cenomanian–Early Turonian). Therefore, the Cenomanian–Turonian boundary interval (CTBI) is placed within the lower part of the Abu Qada Formation, which is characterized by the presence of black shales and low richness of both foraminifera and ostracods. A remarkable increase in TOC values is observed close to the CTBI. Also, the carbon isotope curve shows a distinctive positive δ¹³C anomaly at the same level of the maximum TOC. The comparison between the recorded δ¹³C data and those obtained from other sections worldwide, indicates that the base of the Turonian is placed directly above the δ¹³C excursion. Furthermore, the recorded foraminiferal community shows evidence for the deepening of the environment and extension of the oxygen minimum zone during the CTBI. This conclusion is based on a sequence of bioevents starting with the disappearance of some agglutinated benthic foraminifera, followed by the dominance of opportunistic groups including buliminids, whiteinellids and heterohelicids. Consequently, the studied well may be considered as a local reference section for OAE2.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2020.100463","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91992493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal living coccolithophore distribution in the enclosed coastal environments of the Thessaloniki Bay (Thermaikos Gulf, NW Aegean Sea)","authors":"Dimiza M.D. ,&nbsp;Koukousioura O. ,&nbsp;Michailidis I. ,&nbsp;Dimou V.-G. ,&nbsp;Navrozidou V. ,&nbsp;Aligizaki K. ,&nbsp;Seferlis M.","doi":"10.1016/j.revmic.2020.100449","DOIUrl":"https://doi.org/10.1016/j.revmic.2020.100449","url":null,"abstract":"<div><p><span>Living coccolithophores collected from a yearly time interval, January to December 2016, at the SP1 station of the Thessaloniki Bay, an enclosed coastal environment located in the inner part of the Thermaikos Gulf (Northwestern Aegean Sea) were analyzed to determine their seasonal variation and evaluate the effects of environmental factors on their density, species composition and distribution. Our results showed that coccolithophores constituted a significant component of the phytoplankton<span> community and were characterized by the dominance of few opportunistic species, as an impact of eutrophic environmental conditions. Temperature seasonal cycle and the variations in nutrient inputs from riverine and/or anthropogenic sources seem to control the seasonal pattern of coccolithophores. </span></span><em>Emiliania huxleyi</em> with densities as high as ∼4.0 × 10⁵ cells l⁻¹ predominated during the late spring–early summer, whereas a strong dominance of <em>Gephyrocapsa oceanica</em> with densities ∼2.0 × 10⁵ cells l⁻¹ was observed during the late summer and the autumn. <em>Emiliania huxleyi</em> appeared to dominate the coccolithophore assemblages once more during the winter; while <em>Helicosphaera carteri</em> was continuously present during the wintertime (exceeding ∼2.7 × 10³ cells l⁻¹). <em>Emiliania huxleyi</em><span> was entirely represented by morphotype type A in the studied samples. Morphometric analysis of </span><em>E. huxleyi</em><span> coccoliths indicated that the population is dominated by lightly calcified forms, although an increase of more heavily calcified coccoliths was observed during late autumn-early spring in line with the well-documented seasonal succession pattern of </span><em>E. huxleyi</em> type A forms in the Aegean Sea.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.revmic.2020.100449","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92070083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}