Fig 4 - uploaded by Catherine Riaux-Gobin
Content may be subject to copyright.
a–e, g, h & j. Litheusphaerella cf spectabilis Deflandre form 2. f. & i. L. cf spectabilis Deflandre form 1. k. & l. Archaeomonas cf japonica Deflandre. Scale bars = 0.5 μm (b & e), others = 2 μm.
Source publication
The land-fast ice and the platelet ice layer off Adélie Land are inhabited by a dense and diversified diatom community. Along with Bacillariophyceae, Archaeomonadaceae sensu Deflandre are present and relatively abundant. These modern siliceous nanostructures are similar to the nanofossils described by geologists in marine sediments from upper Creta...
Contexts in source publication
Context 1
... the neck. The cyst of Paraphysomonas imperforata Lucas (Takahashi et al. 1986, fig. 24) also shows some affinities. Spherical to slightly ellipsoid body; Trunconic small collar system, slightly elevated, but lower than spines high. Small spines more or less regularly spread (10-12 along a cyst diameter), with smaller spines distributed in between Fig. 4l may be the same taxon (cf fig. 13 fig. 5, 6.3 large, 6.5 μm high, in Rampi 1940), which differs from A. japonica by an irregular repartition and length of spines (Rampi 1940). Some affinities with A. multipunctata Rampi (Rampi 1969, pl.1, fig. ...
Context 2
... Deflandre (1932a, p. 1861, fig. 6) Litheusphaerella spectabilis Deflandre forma 1 Fig. 4f & i, Fig. 5g Sphaerical body. Wall ornamented with spines irregularly distributed, with thickened, flared tips (10-12 along a cyst diameter); some small spines/knobs are spread among the longer ones. Collar complex not clearly observed. A thin velum seems to joint the tips, the extremity only of the spines being free. Cyst diameter 7-7.8 μm. Height ...
Context 3
... spectabilis Deflandre forma 2 Fig. 4a-e, Fig. 4g & h, Fig. 5h Spherical to slightly ellipsoid body (Fig. 4c). Small collar complex, low and composed of a round-edged ...
Context 4
... spectabilis Deflandre forma 2 Fig. 4a-e, Fig. 4g & h, Fig. 5h Spherical to slightly ellipsoid body (Fig. 4c). Small collar complex, low and composed of a round-edged ...
Context 5
... ornamented with numerous slender spines regularly distributed, (15-20 along a cyst diameter). Depending on the specimen, the spines are more or less aciculate (Fig. 4d) or flared ( Fig. 4c & h) whereas some are composed of three parts (Fig. 4e & j); some small spines/knobs are spread in between the longer ones. The spines bordering the annulus are short (Fig. 4b & c). In some specimens a thin velum joints the tips, only the extremity of the spines being free (Fig. 4a & g). Cyst diameter 7-8.5μm. ...
Context 6
... ornamented with numerous slender spines regularly distributed, (15-20 along a cyst diameter). Depending on the specimen, the spines are more or less aciculate (Fig. 4d) or flared ( Fig. 4c & h) whereas some are composed of three parts (Fig. 4e & j); some small spines/knobs are spread in between the longer ones. The spines bordering the annulus are short (Fig. 4b & c). In some specimens a thin velum joints the tips, only the extremity of the spines being free (Fig. 4a & g). Cyst diameter 7-8.5μm. Height of spines 0.77-0.9 μm. ...
Context 7
... ornamented with numerous slender spines regularly distributed, (15-20 along a cyst diameter). Depending on the specimen, the spines are more or less aciculate (Fig. 4d) or flared ( Fig. 4c & h) whereas some are composed of three parts (Fig. 4e & j); some small spines/knobs are spread in between the longer ones. The spines bordering the annulus are short (Fig. 4b & c). In some specimens a thin velum joints the tips, only the extremity of the spines being free (Fig. 4a & g). Cyst diameter 7-8.5μm. Height of spines 0.77-0.9 μm. Annulus diameter 0.82-1.08 μm. Diameter of the pore ...
Context 8
... with numerous slender spines regularly distributed, (15-20 along a cyst diameter). Depending on the specimen, the spines are more or less aciculate (Fig. 4d) or flared ( Fig. 4c & h) whereas some are composed of three parts (Fig. 4e & j); some small spines/knobs are spread in between the longer ones. The spines bordering the annulus are short (Fig. 4b & c). In some specimens a thin velum joints the tips, only the extremity of the spines being free (Fig. 4a & g). Cyst diameter 7-8.5μm. Height of spines 0.77-0.9 μm. Annulus diameter 0.82-1.08 μm. Diameter of the pore 0.45-0.5 ...
Context 9
... the spines are more or less aciculate (Fig. 4d) or flared ( Fig. 4c & h) whereas some are composed of three parts (Fig. 4e & j); some small spines/knobs are spread in between the longer ones. The spines bordering the annulus are short (Fig. 4b & c). In some specimens a thin velum joints the tips, only the extremity of the spines being free (Fig. 4a & g). Cyst diameter 7-8.5μm. Height of spines 0.77-0.9 μm. Annulus diameter 0.82-1.08 μm. Diameter of the pore 0.45-0.5 ...
Similar publications
1 The raphid pennates (order Bacillariales) are a diverse group of diatoms easily recognized by 2 having a slit in the siliceous cell wall, called the raphe, with functions in cell motility. It has 3 been hypothesized that this morphological innovation contributed to the evolutionary success 4 of this relatively young but species-rich group of diat...
Citations
... Chrysophytes are known for their capacity of the endogenous deposition of silica (Kristiansen and Š kaloud, 2016) and fossilized chrysophytes are common in ancient sedimentary records due to the resistant siliceous structures. However, the oldest certain fossils of chrysophytes are recovered from Upper Cretaceous marine deposits (Riaux-Gobin and Stumm, 2006), much younger than the Late Paleozoic age of the Fengcheng Formation. And the oldest siliceous scales and bristles of chrysophytes, which are very resistant and commonly preserved, have been reported from the Paleogene age (Kristiansen and Š kaloud, 2016). ...
Siliceous mudstones and chert-shale couplets are primary source rocks for many large paleo-oil reservoirs over the world. It is well established that photosynthetic organisms can be exceptionally well preserved in silica precipitates, but the fate of the trapped organic matter (OM) during burial remains poorly studied. Here, dense unicellular microbial fossils have been recently discovered in the cherts of the Late Paleozoic alkaline saline lake deposit in NW Junggar Basin, NW China. We use petrographic observations and organic geochemical analysis to study the origin of unicellular microbes and how silicified organic matter generate and expel hydrocarbons. A 300-m-long oil shale core shows overall low levels of porosity, permeability and total organic carbon contents
(generally <0.5 wt%), but very high extracts (on average 0.26 wt%), suggesting that the rich extracts were mostly indigenous and the original organic matter had a high hydrocarbon conversion. Analysis of biomarkers and silicified fossils both suggest that the bio-precursor for the organic matter is a special green alga. Reconstruction of silica diagenesis of cherts indicates that both the trapped lipids and hydrocarbons in silicified microbial cells and extracellular polymeric substances had been effectively expelled out during the transformations of Opal-A to microcrystalline quartz and during OM thermal maturation. Exceptional OM preservation and effective oil expelling ways render siliceous source rocks as excellent unconventional hydrocarbon reservoirs.
... Stomatocyst terminology follows the guidelines of International the Statospore Working Group (ISWG) (Cronberg & Sandgren 1986), with modifications described by Duff et al. (1995) and Wilkinson et al. (2001). The morphology of the new morphotypes was compared with the ultrastructure of known stomatocysts worldwide (Rybak et al. 1991, Duff et al. 1995, Facher & Schmidt 1996, Van de Vijver & Beyens 2000, Hansen 2001, Pla 2001, Wilkinson et al. 2001, Wołowski et al. 2004, Firsova & Likhoshway 2006, Riaux-Gobin & Stumm 2006, Coradeghini & Vigna 2008, Huber et al. 2009, Pang & Wang 2017, Kato 2019. ...
... Deflandre (1932) proposed a classification system for chrysophycean stomatocysts, classifying the stomatocysts produced by unidentifiable fossil, marine forms into an artificial family -Archaeomonadaceae. Since then the modern marine chrysophycean stomatocysts and their fossils collected from the Southern Ocean, the Arctic Ocean and the Norwegian Sea are often referred as Archaeomonadaceae (Zanon 1947, Rampi 1969, Gombos 1977, Perch-Nielsen 1978, Mitchell 1982, Takahashi et al. 1986, Stoecker et al. 1997, Riaux-Gobin & Stumm 2006, Kato 2019). But most were described based on LM observation. ...
Chrysophyte algae live predominantly in freshwater habitats, therefore marine chryso-phyte stomatocysts are less common and poorly documented. Here we report on the occurrence of two unknown chrysophycean stomatocysts in a complex epizoic biofilm formed on a carapace of a loggerhead sea turtle (Caretta caretta) found injured on the southeastern coast of the Adriatic Sea and admitted to the Sea Turtle Rescue Centre in Aquarium Pula, Croatia. Stomatocyst #1 is characterized by a thickened circulus giving the cyst an asymmetrical outlook whereas stomatocyst #2 has a thick, wide, irregularly shaped collar. Detailed morphological investigations based on scanning electron microscopy observations and comparison with known chrysophyte stomatocysts worldwide , showed that both should be described as new to science following the guidelines of the International Statospore Working Group (ISWG).
... However, the relatively unknown species-specific ecology is apparent through the discrepancies that different studies have in the interpretation of diatom ecologies. For instance, Fragilariopsis cylindrus is not regarded as a straightforward sea-ice indicator species in Oksman et al. (2019) but is in Ren et al. (2009) Stumm, 2006). The Archaeomonas cysts are relatively common in core and surface sediment samples from the MIZ in the Arctic but are rarely included in counts (Weckström, 2019, Personal Communication). ...
... The chrysophyte cysts Archaeomonas sp. is a species that is described in the land-fast ice and platelet ice off of Antarctica and shown to be present in diverse marine conditions, particularly around sea-ice break up (Riaux-Gobin & Stumm, 2006 does have high abundances in high aSIC, but its ecology does not appear to be associated just to aSIC. Indeed, the RDA (Figure 9) indicates that Archaeomonas sp. is a 'cold mixed' water species related to low aSIC and to cold aSST, analogous to the separated F. oceanica and R. ...
... The northern Baffin Bay site had a comparable moderate abundance (7.3%) at very high aSIC (94.4%). The abundances in the high to very high aSIC and strong Arctic Water were high, but generally lower than they were in southern Baffin Bay, where the aSST were fractionally warmer due to the upwelling Irminger Current derived waters.The chrysophyte cysts Archaeomonas sp. are certainly abundant in the diverse sea-ice environments of the northern North Atlantic in addition to the Antarctic marine environment(Riaux-Gobin & Stumm, 2006). The highest abundances are found in the very high aSIC (91.3%-98.9%) of western Baffin Bay (23.9%) and western Davis Strait (42.7%), as well as the central western Davis Strait site (30.3%) which had no aSIC. ...
Significant changes in sea-ice variability have occurred in the northern North Atlantic since the last deglaciation, resulting in global scale shifts in climate. By inferring the dynamic changes of palaeo sea-ice to past changes in climate, it is possible to predict future changes in response to anthropogenic climate change. Diatoms allow for detailed reconstructions of palaeoceanographic and sea-ice conditions, both qualitatively, using information of species ecologies and quantitatively, via a transfer function based upon diatom species optima and tolerances of the variable to be reconstructed. Three diatom species comprising a large portion of the training set are proxies for the presence of sea ice: Fragilariopsis oceanica, Fragilariopsis reginae-jahniae and Fossula arctica, have currently been grouped into one species – F. oceanica – in the large diatom training set of the northern North Atlantic region. The clustering of the species may result in an imprecise reconstruction of sea ice that does not take into account all the available ecological information.
The proportions of the three species were recounted from the original surface sediment slides alongside the additional chrysophyte cyst Archaeomonas sp. and statistically analysed using Canoco and the R software package eHOF. A core from Kangerlussuaq Trough comprising the Late Holocene (~690–1498 Common Era) was also recounted and analysed using C2.
The separated diatom species and chrysophyte cyst Archaeomonas sp. exhibited different relationships to both sea-ice concentration (aSIC) and sea surface temperature (aSST). The separated F. oceanica is a ‘cold-mixed’ water species occurring at cold aSST and both low and high aSIC. High abundances occur in the marginal ice zone (MIZ) where surficial meltwater is high during the spring bloom, with additional inputs from glacial meltwaters nearshore. F. reginae-jahniae is a sea-ice associated species related to cold aSST and high aSIC. High abundances occur in the low salinity Arctic Water dominated MIZ which experiences significant aSIC. F. arctica is a sea-ice associated species related to cold aSST and high aSIC. High abundances occur in the low salinity Arctic Water dominated MIZ which experiences high aSIC, particularly in polynya conditions. F. arctica can be considered a characteristic polynya species at high abundances. Archaeomonas sp. is a ‘cold-mixed’ water species related to both cold and relatively warm aSST and low and high aSIC. High abundances occur in both relatively warm ice-free Atlantic Water and also in cold high aSIC Arctic Water conditions rendering it a more complex indicator for aSST or aSIC proxy. However, the aversion to MIZ conditions indicates that Archaeomonas sp. is associated with a relatively saline unstratified water column. This is the first time that the distribution and ecology of Archaeomonas sp. has been presented. As such, the ecology described here can be used in future studies. The separation of the three diatom species is crucial for the ecological interpretation of downcore assemblage changes. It is also crucial for the application of transfer functions in order to have greater precision in reconstructing aSIC and assessing the influence of Arctic Water or Atlantic Water, even at low abundances.
... However, the relatively unknown species-specific ecology is apparent through the discrepancies that different studies have in the interpretation of diatom ecologies. For instance, Fragilariopsis cylindrus is not regarded as a straightforward sea-ice indicator species in Oksman et al. (2019) but is in Ren et al. (2009) Stumm, 2006). The Archaeomonas cysts are relatively common in core and surface sediment samples from the MIZ in the Arctic but are rarely included in counts (Weckström, 2019, Personal Communication). ...
... The chrysophyte cysts Archaeomonas sp. is a species that is described in the land-fast ice and platelet ice off of Antarctica and shown to be present in diverse marine conditions, particularly around sea-ice break up (Riaux-Gobin & Stumm, 2006 does have high abundances in high aSIC, but its ecology does not appear to be associated just to aSIC. Indeed, the RDA (Figure 9) indicates that Archaeomonas sp. is a 'cold mixed' water species related to low aSIC and to cold aSST, analogous to the separated F. oceanica and R. ...
... The northern Baffin Bay site had a comparable moderate abundance (7.3%) at very high aSIC (94.4%). The abundances in the high to very high aSIC and strong Arctic Water were high, but generally lower than they were in southern Baffin Bay, where the aSST were fractionally warmer due to the upwelling Irminger Current derived waters.The chrysophyte cysts Archaeomonas sp. are certainly abundant in the diverse sea-ice environments of the northern North Atlantic in addition to the Antarctic marine environment(Riaux-Gobin & Stumm, 2006). The highest abundances are found in the very high aSIC (91.3%-98.9%) of western Baffin Bay (23.9%) and western Davis Strait (42.7%), as well as the central western Davis Strait site (30.3%) which had no aSIC. ...
... Type locality and age of Archaeomonas areolata are Karand, Hungary and Miocene, respectively (Defl andre, 1933). Specimens of Perch-Nielsen (1978) and Riaux-Gobin & Stumm (2006) are from the Vøring Plateau, Norwegian Sea (DSDP Hole 338) and the land fast ice in the vicinity of Adélie Land (East Antarctica), respectively. Similar cyst: This cyst resembles A. ornata Rampi (Fig. 92) but diff ers in the lack of small spines in the center of the lacunae. ...
The late Miocene and Pliocene (~9–3 Ma) fossil chrysophyte cysts from Ocean Drilling Program Site 689 and Deep Sea Drilling Project Site 513 in the Southern Ocean are described and illustrated. Both SEM and LM observations and micrographs are presented for 38 taxa of chrysophyte cysts from 10 selected samples. Of these chrysophyte cysts, 27 are newly described in this study.
... Studies on chrysophyte cysts in the Southern Hemisphere have revealed their various habitats: in modern freshwater bodies such as lakes, streams, on glaciers and ice sheets in the Antarctic and subantarctic regions (Parker et al., 1972;Oguni & Takahashi, 1989;Van de Vijver & Beyens, 1997a;Mrozińska et al., 1998;Remias et al., 2013), in modern sea-ice and seawater (Mitchell & Silver, 1982;Takahashi et al., 1986;Stoecker et al., 1997;Riaux-Gobin & Stumm, 2006), from Antarctic and subantarctic terrestrial sediments (Scherer, 1991;Van de Vijver & Beyens, 1997b;Konfi rst et al., 2011;Warnock & Doran, 2013) and marine sediments (Perch-Nielsen, 1975;Sjunneskog & Winter, 2012). ...
Fossil chrysophyte cysts are considered to be potentially useful paleoenvironmental indicators, however no general consensus exists about their paleoenvironmental significance due to sparse information regarding their ecology and taxonomic difficulties. Data on fossil chrysophyte cyst abundances of late Miocene to Pliocene (ca. 9–3 Ma) age are presented from two marine sediment cores, Ocean Drilling Program Site 689 and Deep Sea Drilling Project Site 513, both located in the Atlantic sector of the Southern Ocean. Changes in the chrysophyte cyst abundances are compared to those in the diatom assemblages, and the potential of fossil chrysophyte cysts as paleoceanographic indicators around Antarctica is discussed. Coexistences of chrysophyte cysts with freshwater diatoms (4.8–4.5 Ma in Site 689; 9.1–8, 7–6, 5.4–5. 1 Ma in Site 513) or ice rafted debris (4.8–3. 4 Ma in Site 513) seem to indicate that the occurrences of fossil chrysophyte cysts in the Southern Ocean are mainly derived from Antarctic terrestrial freshwater habitats (i. e., lakes on glaciers, ice sheet). On the other hand, the coexistence of chrysophyte cysts and sea-ice related diatoms (4.4–3. 3 Ma at Site 689) suggests that some of the chrysophyte cysts are originated from sea-ice. Further taxonomic and stratigraphic studies on fossil chrysophyte cysts are needed to provide a new approach for paleoenvironmental reconstruction.
... Therefore, they may belong to any unrelated or even extinct lineage. The oldest certain fossils of chrysophytes are represented by siliceous stomatocysts of Archaemonadaceae, recovered from Tertiary or Upper Cretaceous marine deposits (Riaux-Gobin and Stumm 2006). At present, the oldest stomatocysts are from Southern Ocean sediments of Lower Cretaceous (Aptian-Albian, $ 112 Ma), which may indicate the initiation of silicification within chrysophyte algae (Harwood and Gersonde 1990). ...
The chrysophytes (more than 1,200 described species) are unicellular or colonial algae characterized by heterokont flagella and chloroplasts with chlorophyll a and c, and by their endogenous silicified stomatocysts. They occur mainly as phytoplankton in temperate freshwaters, and their distribution is ecologically determined, mainly by temperature and pH.
Cells are naked or in many cases surrounded by an envelope, e.g., of species-specific silica scales manufactured from the chloroplast ER and Golgi vesicles and transported to the cell membrane and extruded. Photoreceptor systems include a swelling on the short flagellum and a corresponding stigma in one of the chloroplasts. Photosynthesis results in chrysolaminaran. But in many species, e.g., in colorless species, organic compounds can be taken up from the water or by phagocytosis. Life history includes mitotic divisions and encystment. In many species, sexuality – cell fusion followed by encystment of the zygote – has been observed. Classification was traditionally based on morphological criteria, including ultrastructure, but in recent years molecular methods have resulted in profound changes in our concepts of relationships and evolution.
... Therefore, they may belong to any unrelated or even extinct lineage. The oldest certain fossils of chrysophytes are represented by siliceous stomatocysts of Archaemonadaceae, recovered from Tertiary or Upper Cretaceous marine deposits (Riaux-Gobin and Stumm 2006). At present, the oldest stomatocysts are from Southern Ocean sediments of Lower Cretaceous (Aptian-Albian, $ 112 Ma), which may indicate the initiation of silicification within chrysophyte algae (Harwood and Gersonde 1990). ...
The chrysophytes (more than 1,200 described species) are unicellular or colonial algae characterized by heterokont flagella and chloroplasts with chlorophyll a and c, and by their endogenous silicified stomatocysts. They occur mainly as phytoplankton in temperate freshwaters, and their distribution is ecologically determined, mainly by temperature and pH.
Cells are naked or in many cases surrounded by an envelope, e.g., of species-specific silica scales manufactured from the chloroplast ER and golgi vesicles and transported to the cell membrane and extruded. Photoreceptor systems include a swelling on the short flagellum and a corresponding stigma in one of the chloroplasts. Photosynthesis results in chrysolaminaran. But in many species, e.g., in colorless species, organic compounds can be taken up from the water or by phagocytosis. Life history includes mitotic divisions and encystment. In many species, sexuality – cell fusion followed by encystment of the zygote – has been observed. Classification was traditionally based on morphological criteria, including ultrastructure, but in recent years molecular methods have resulted in profound changes in our concepts of relationships and evolution.
... In a study about recent archaeomonadines off East Antarctica (e.g. Riaux-Gobin & stuMM, 2006), different stages of wall development of cysts are shown. The forms described as Litheusphaerella spectabilis DefLanDRe forma 1 and 2, therein (Riaux-Gobin & stuMM, 2006: Fig. 4, L. cf. ...
This publication presents a taxonomical and stratigraphical compilation of type specimens of Silicoflagellata (Dictyochales) and Archaeomonadacea designated by Herbert Stradner, alone or with colleagues, and deposited in the Palaeontological Collection of the Geological Survey of Austria (GBA) in Vienna. A complete list of relevant
publications is given in the index and fully included in the references.
... Most Antarctic sea ice reconstructions were inferred from diatoms assemblages (Armand and Leventer, 2003 for review) and more recently from diatom biomarkers (Massé et al., 2011). However, other groups of siliceous organisms have been shown to thrive in close association with sea ice (Zielinski, 1997;Scott and Marchant, 2005;Riaux-Gobin et al., 2006). When preserved in sediments, the hard part of these organisms may provide additional information on past environmental conditions. ...
... Several traverses were performed on three slides per sample to achieve the counts. Taxonomy followed Zielinski (1997), Scott and Marchant (2005) and Riaux-Gobin et al. (2006). ...
... Ecology: Archeomonas have been observed in sea ice and seawater from Antarctica and Southern Baltic Sea (Takahashi et al., 1986;Riaux-Gobin et al., 2003). In the Adélie Land region, several species have been identified within sea ice and platelet ice as well as adjacent water masses (Riaux-Gobin, 2006) in low oceanic circulation and silicarich marine conditions (Mitchell and silver, 1986). ...
