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1
Barron, John A., und Jack G. Baldauf. „Cenozoic Marine Diatom Biostratigraphy and Applications to Paleoclimatology and Paleoceanography“. Short Courses in Paleontology 8 (1995): 107–18. http://dx.doi.org/10.1017/s2475263000001446.
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Diatoms, golden brown algae, are present in most aqueous environments. Within the marine environment marine diatoms occupy the photic zone and represent the lowest level of the marine food chain. Diatoms are either planktonic or benthic and possess an external siliceous skeleton or frustule, that is boxlike in structure. The size of diatom frustules ranges from less than 1 μm to more than 1,000 μm, but most frustules range in size from 10 to 100 μm. Diatoms are present in the geological record from at least the Cretaceous (Harwood and Nikolaev, this volume) and have numerous advantages for biostratigraphic correlation and paleoenvironmental reconstruction of marine sedimentary sequences. This chapter summarizes the current state of marine diatom biostratigraphy for the Cenozoic and provides examples of how marine diatoms are used in paleoenvironmental reconstructions. No attempt is made to illustrate the various diatom taxa discussed; the reader is referred to published references such as the syntheses of Fenner (1985) and Barron (1985).
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Gogorev, R. M., und Z. V. Pushina. „Some centric diatoms (Bacillariophyta) from Neogene deposits of the Fisher Massif (Prince Charles Mountains, East Antarctica)“. Novosti sistematiki nizshikh rastenii 45 (2011): 32–49. http://dx.doi.org/10.31111/nsnr/2011.45.32.
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The richest diatom complexes have revealed due to the study of glacial-marine sediments sampled in the Fisher Massif (Prince Charles Mountains, East Antarctica) during 52nd and 53rd Russian Antarctic Expeditions (Polar Marine Geol. Survey Expedition) in 2006/07 and 2007/08. Three diatom complexes are distinguished according to different palaeoecological conditions: the planktonic one is located in the basis of the outcrop, while mixed planktonic-benthic and benthic ones being located above. The planktonic diatom complexes are dominated by two oceanic species Actinocyclus ingens (up to 8%) and Denticulopsis simonseni (up to 80%). There are 15 planktonic algae, e. g. Eucampia аntarctica, Fragilariopsis spp., Rhizosolenia spp., Rouxia antarctica, Podosira antarctica sp. nov., Stellarima microtrias; and also unknown and non-described benthic diatoms Achnanthes sp., Cocconeis spp., Rhabdonema (s. l.) spp. and Synedra (s. l.) spp. Detailed data on morphology and taxonomy of 10 centric diatoms are presented, including 3 newly described species.
3
David, Louis. „Marine benthic diatoms in China“. Geobios 19, Nr. 5 (Januar 1986): 670. http://dx.doi.org/10.1016/s0016-6995(86)80066-3.
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Sullivan, Michael J. „Marine benthic diatoms in China“. Marine Geology 76 (Januar 1987): 334–35. http://dx.doi.org/10.1016/0025-3227(87)90044-2.
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Martínez, Yuriko Jocselin, David Alfaro Siqueiros-Beltrones und Ana Judith Marmolejo-Rodríguez. „Response of Benthic Diatom Assemblages to Contamination by Metals in a Marine Environment“. Journal of Marine Science and Engineering 9, Nr. 4 (19.04.2021): 443. http://dx.doi.org/10.3390/jmse9040443.
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Studies on marine benthic diatoms in environments contaminated by metals are scarce. The typical structure of benthic diatom assemblages (species richness, diversity, dominance, dominant taxa) from undisturbed environments may be used as reference for contrasting with contaminated environments in order to observe how said assemblages respond to such disturbance. Thus, the Ho that the structure of benthic diatom associations and morphology of their frustules under contamination by metals would be normal, as in unpolluted environments was tested. To do this, concentrations of 24 metals were surveyed in a coastal zone impacted by mining residues, and the structure of benthic local diatom assemblages was described. Metal concentrations measurements for 15 metals surpassed the normal values of the upper earth cortex, seven were under the low range effect, and three (Cd, Cu, Zn) surpassed the medium range effect values. At a control site no element concentration was above the reference values for low range effect (LRE) or medium range effect (MRE) standards. There, diatom species richness (S) was high, particularly on seaweeds; where, 397 diatom taxa were recorded. In contrast, at the contaminated area 217 diatom taxa were recorded, but diversity (H’) ranged from 2.4 to 4.3. Relative high frequencies of deformed diatom valves mainly of Achnanthes spp. were recorded in contaminated sediments. In general, diatom taxocenoses presented a typical structure for non-contaminated environments. However, scarceness of specimens, lower S, and frequency of deformed valves suggest responses to metal contamination. For marine environments, the latter values corresponding to A. longipes may be considered a reliable reference to the response of benthic diatoms to metal contamination.
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Tsoy, I. B., und I. A. Prushkovskaya. „Diatoms in Surface Sediments of the Academy Bay of the Sea of Okhotsk“. Биология моря 49, Nr. 2 (01.03.2023): 82–93. http://dx.doi.org/10.31857/s0134347523020092.
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The study of diatoms in the surface sediments of the Academy Bay (Sea of Okhotsk) revealed a rich diatom flora (187 species and intraspecific taxa), represented mostly by marine and brackish water species. The predominance of benthic-planktonic and benthic species indicates a significant role of microphytobenthos in the Academy Bay. The diatom assemblages distinguished with the use of cluster analysis are homogeneous in their taxonomic composition, but differ in ecological structure, which is mainly determined by water salinity. The concentration of diatoms in the sediments in the open part of the Academy Bay and in the apex of the Ulban Bay depends on a high productivity of waters and the lithological composition of sediments. A relatively low content of diatoms in the sediments is associated with the severe climatic conditions of the region that is close to the Arctic.
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Harvey, Ben P., Sylvain Agostini, Koetsu Kon, Shigeki Wada und Jason M. Hall-Spencer. „Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises“. Diversity 11, Nr. 12 (16.12.2019): 242. http://dx.doi.org/10.3390/d11120242.
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Diatoms are so important in ocean food-webs that any human induced changes in their abundance could have major effects on the ecology of our seas. The large chain-forming diatom Biddulphia biddulphiana greatly increases in abundance as pCO2 increases along natural seawater CO2 gradients in the north Pacific Ocean. In areas with reference levels of pCO2, it was hard to find, but as seawater carbon dioxide levels rose, it replaced seaweeds and became the main habitat-forming species on the seabed. This diatom algal turf supported a marine invertebrate community that was much less diverse and completely differed from the benthic communities found at present-day levels of pCO2. Seawater CO2 enrichment stimulated the growth and photosynthetic efficiency of benthic diatoms, but reduced the abundance of calcified grazers such as gastropods and sea urchins. These observations suggest that ocean acidification will shift photic zone community composition so that coastal food-web structure and ecosystem function are homogenised, simplified, and more strongly affected by seasonal algal blooms.
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Sas, Ahmed Awadh, Su Nyun Pau Suriyanti, Simon Kumar Das und Zaidi Che Cob. „Effect of Seawater and Surface-Sediment Variables on Epipelic Diatom Diversity and Abundance in the Coastal Area of Negeri Sembilan, Malaysia“. Water 14, Nr. 19 (10.10.2022): 3187. http://dx.doi.org/10.3390/w14193187.
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Benthic diatoms are important components of marine shallow-water habitats that may affect primary production, stabilize sediment, and produce extracellular polymeric substances. Benthic diatoms are useful for estimating the trophic status of marine ecosystems. In this study, we investigated the diversity and abundance of benthic diatoms to integrate these data with the physicochemical characteristics of shallow coastal areas in Negeri Sembilan. A total of 39 species of epipelic diatoms were extracted by removing organic matter from sediments that were dominated by pennate diatoms. Results showed that Diploneis crabro, Eunotogramma laevis, Actinoptychus sp., and Cocconeisplacentula were the important species in the area. The abundance varied between 1.85 × 103 and 3.43 × 103 cells/g, and the diversity index fluctuated between 2.13 and 2.58. The abundance had significant positive correlations with seawater surface temperature (SST) but had negative correlations with pH and NH3. The diversity on the other end was positively correlated with SST but negatively correlated with total suspended solids and SiO2. Principal component analysis (PCA) demonstrated that the abundance of D. crabro, E. laevis, and Actinoptychus sp. can be attributed to high levels of NO2−, NH3, and total dissolved solids. PCA also showed positive correlations of C. placentula with NO3−and SiO2 but negative ones with PO43− and pH. The epipelic diatom community showed high diversity with high variations throughout the study area.
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Zidarova, Ralitsa, Plamen Ivanov, Elitsa Hineva und Nina Dzhembekova. „Diversity and habitat preferences of benthic diatoms from South Bay (Livingston Island, Antarctica)“. Plant Ecology and Evolution 155, Nr. 1 (30.03.2022): 70–106. http://dx.doi.org/10.5091/plecevo.84534.
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Background and aims – Despite a long research history, knowledge of Antarctic marine benthic diatoms is fragmentary. This study reports on marine benthic diatoms from South Bay, Livingston Island, focusing on diatoms living on hard substrata, and species distribution across different coastal habitats.Material and methods – Samples were collected from tidal pools (19), intertidal cobbles (9), artificial substrata installed at various depths (10), coastal rocks (2), and bottom sediments at depths > 20 m (2). Species identifications and community analyses were done using LM with additional information obtained using SEM. nMDS based on diatom abundance data was applied to display differences between the samples by habitat/substratum type and sampling month. The significance of the habitat/substratum type and sampling month on diatom communities was checked with PERMANOVA. Similarity/dissimilarity within and between sample groups and their contributing species were explored with SIMPER.Key results – In total, 133 diatom taxa were recorded, of which 110 are benthic. A large number of taxa could not be certainly identified. Taxonomic remarks and ecology and distribution data for some rarely reported species with convoluted taxonomic and nomenclatural histories are given. One new combination is proposed. Diatom communities were influenced by the habitat/substratum type, but not by seasonality. Significant differences existed between communities in tidal pools and those on cobbles, artificial substrata, and sediments, and between those on sediments and artificial substrata. Navicula aff. perminuta dominated on cobbles and often on artificial substrata. Species forming mucilage tubes, tree-like colonies, and chains of cells embedded in mucilage were restricted to tidal pools.Conclusion – Benthic diatom communities from South Bay are highly diverse and species show distinct distributions in the coastal habitats, but the scarce studies and often confusing nomenclature history of the taxa make their identification challenging, and potentially common species for the region remain unknown.
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Andrews, G. W. „The marine benthic diatoms in China“. Palaeogeography, Palaeoclimatology, Palaeoecology 59 (Januar 1987): 325. http://dx.doi.org/10.1016/0031-0182(87)90089-7.
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Wulff, Angela, Katharina Zacher, Dieter Hanelt, Adil Al-Handal und Christian Wiencke. „UV radiation - a threat to Antarctic benthic marine diatoms?“ Antarctic Science 20, Nr. 1 (12.10.2007): 13–20. http://dx.doi.org/10.1017/s0954102007000739.
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AbstractThis investigation was motivated by the lack of ultraviolet radiation (UVR, 280–400 nm) studies on Antarctic benthic marine microalgae. The objective was to estimate the impact of UV-B (280–315 nm) and UV-A (315–400 nm), on photosynthetic efficiency, species composition, cell density and specific growth rate in a semi-natural soft-bottom diatom community. In both experiments, cell density increased over time. The most frequently observed species were Navicula cancellata, Cylindrotheca closterium, Nitzschia spp., and Petroneis plagiostoma. For both experiments, a shift in species composition and a decreased photosystem II (PSII) maximum efficiency (Fv/Fm) over time was observed, irrespective of treatment. UVR significantly reduced Fv/Fm on days 3 and 10 (Expt 1), disappearing on the last sampling date. A similar trend was found in Expt 2. A significant UV effect on cell density was observed in Expt 1 (day 10) but not in Expt 2. No treatment effects on species composition or specific growth rate were found. Thus, the UV effects were transient (photosynthetic efficiency and cell density) and the growth of the benthic diatoms was generally unaffected. Overall, according to our results, UVR does not seem to be a threat to benthic marine Antarctic diatoms.
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Bilous, Olena P., Agata Z. Wojtal, Natalia O. Ivanova, Petro M. Tsarenko, Olga V. Burova und Sophia Barinova. „Benthic Diatom Composition in Coastal Zone of Black Sea, Sasyk Reservoir (Ukraine)“. Diversity 12, Nr. 12 (01.12.2020): 458. http://dx.doi.org/10.3390/d12120458.
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The Sasyk Reservoir is one of the largest seaside reservoirs in Ukraine, artificially maintained as a freshwater area including various floodplain areas. The Reservoir originated from an estuary to now being an almost freshwater reservoir. The diatoms (Bacillariophyta) in benthos were investigated for analyzing the coastal zone diversity of the Black Sea inside the borders of Ukraine. The indicated diatom composition was formed by 97 species (100 infraspecies taxa). Some rare marine and freshwater taxa were noted, as well as three species reported in Ukrainian territory for the first time (Navicula vandamii Schoeman et R.E.M. Archibald, Sellaphora difficillima (Hustedt) C.E. Wetzel, L. Ector et D.G. Mann, and Mastogloia laterostrata Hustedt). The bioindicative characteristics of the diatom composition testified to the freshwater condition of the reservoir. Changes to the salinity level of the Sasyk Reservoir were exposed due to the composition of benthic diatoms. The presence of mesohalobous species (7 taxa) acknowledges conditions that are typical for estuaries and mouths of rivers and reveals the salinity changes in the Sasyk Reservoir. Likewise, the prevailing number of oligohalobous diatoms (61 taxa) reveal presence of freshwater in the reservoir. The implementation of the Polish phytobenthos lake assessment method for the nearby Ukrainian Reservoir was conducted for the first time. The multimetric Diatom Index for lake values varied from 0.39 to 0.76, and revealed alterations in the status over the Sasyk sites, ranging from good, moderate, to poor. Thus, it may be concluded that the current ecological status relating to the composition of benthic diatoms of the reservoir located in the coastal zone of the Black Sea is evaluated as having a moderate status class with some exceptions.
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Kaleli, Aydın, und Reyhan Akçaalan. „Checklist of marine diatoms from the Turkish coastal waters with updated nomenclature“. Aquatic Research 4, Nr. 1 (2021): 88–115. http://dx.doi.org/10.3153/ar21008.
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Marine diatom research in the coastal waters of Turkey started nearly two centuries ago. In the last decades, in-creasing numbers of contri-butions extended the knowledge of the marine phytoplankton. While sev-eral studies dedicated to planktonic forms and the checklists published con-cerning on the phytoplank-ton, relatively low numbers of benthic diatom studies were performed. Therefore, this is the first detailed list of the marine diatoms in-cluding both planktonic and benthic forms in Turkish coasts. This paper brings up the checklist of the past re-search referring to the au-thors in the last two centu-ries within the scope of the latest nomenclature. A total of 767 taxa (species, varie-ties and forms) belonging to 183 genera were listed. This study focussed into the study areas according to the reviewed literature and showed that many areas are yet to be investigated.
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Riaux-Gobin, Catherine. „The diatom genus Cocconeis from an intertidal mud flat of North Brittany: source and diversity“. Canadian Journal of Botany 69, Nr. 3 (01.03.1991): 597–601. http://dx.doi.org/10.1139/b91-081.
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A 1 -year survey of an epipelic diatom assemblage from a North Brittany marine mud flat revealed the presence of 23 species of Cocconeis. About 10 of these species were common, and the remaining ones were rare. These species of Cocconeis for the most part have small dimensions (nannophytobenthos). The species collected from the intertidal sediment, the specific richness, and seasonal occurrences are compared with those of an epiphytic assemblage on Zostera marina L. from the same region. Key words: benthic diatoms, Cocconeis, North Brittany, mud flat.
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LÓPEZ-FUERTE, FRANCISCO OMAR, und DAVID ALFARO SIQUEIROS BELTRONES. „A checklist of marine benthic diatoms (Bacillariophyta) from Mexico“. Phytotaxa 283, Nr. 3 (07.11.2016): 201. http://dx.doi.org/10.11646/phytotaxa.283.3.1.
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This article summarizes nearly three decades of research on marine benthic diatoms from coastal areas in Mexico. The studies analyzed yielded 1162 taxonomic entities that include species, varieties, and forms, plus a considerable number of informal designations; i.e., “aff.” and “cf.”. The taxonomic list resulted from surveying all available published data on the topic, mostly by the authors, from northwest and southeast Mexico, with the objective of providing an up-to-date basis for further research on benthic diatoms from Mexico and related areas. Members of the Class Bacillariophyceae are the best represented with 881 taxa, followed by the Coscinodiscophyceae and Fragilariophyceae with 165 and 116 taxa, respectively. This is the first floristic list of benthic marine diatoms for Mexico, and it shows that many areas of the country’s extensive coastal zone are yet to be surveyed, while simultaneously providing a basis for future ecological and biogeographical studies.
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KAWAMURA, Tomohiko. „Taxonomy and Ecology of Marine Benthic Diatoms.“ Marine fouling 10, Nr. 2 (1994): 7–25. http://dx.doi.org/10.4282/sosj1979.10.2_7.
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Witak, Małgorzata, Jarosław Pędziński, Sandra Oliwa und Dominika Hetko. „Biodiversity of benthic diatom flora in the coastal zone of Puck Bay (southern Baltic Sea): a case study of the Hel Peninsula“. Oceanological and Hydrobiological Studies 49, Nr. 3 (25.09.2020): 304–18. http://dx.doi.org/10.1515/ohs-2020-0027.
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AbstractThe paper presents the results of the analysis of diatoms from surface sediments (stones, sands) and macroflora (seagrass, macroalgae) collected at 16 sampling sites located along the inner coastal zone of Puck Bay (southern Baltic Sea) along the Hel Peninsula. The main diatom species of epilithon, epipsammon and epiphyton were characterized with respect to their autecological preferences (habitat, salinity, trophic status, saprobity). Three groups of diatoms were distinguished with respect to the type of substrate based on the results of benthic flora analysis: diatoms (i) of one type of substrate, (ii) of two types and (iii) those occurring on all types of substrates. Moreover, the distribution of benthic diatom communities indicates ecological differences in the study area. Marine and brackish-water species were observed in large numbers in the coastal zone of the Outer Puck Bay, whereas freshwater flora occurred with a higher frequency in the coastal zone of the Puck Lagoon. The content of polysaprobionts and of α-mesosaprobionts indicates that the region of the Hel Tip is highly eutrophicated and very polluted. The coast in the vicinity of Kuznica is less polluted, whereas the best environmental conditions are found in the Jurata–Jastarnia region, as evidenced by the frequency of diatoms that are β-mesosaprobionts.
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Somma, Emanuele, Antonio Terlizzi, Maria Costantini, Madalena Madeira und Valerio Zupo. „Global Changes Alter the Successions of Early Colonizers of Benthic Surfaces“. Journal of Marine Science and Engineering 11, Nr. 6 (15.06.2023): 1232. http://dx.doi.org/10.3390/jmse11061232.
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The successions of benthic communities over time are strongly influenced by the first colonizers, because surface associations are facilitated by modifications to the adhesive properties promoted by primary colonizers, such as bacteria, protozoans, diatoms, algal propagules, spores, and invertebrate larvae. Bacteria are often the first colonizers on marine submerged surfaces, both organic (e.g., algae, seagrasses and invertebrates) and inorganic. However, they are promptly followed by diatoms and other microorganisms. Consequently, diatoms may represent key elements in the determination of the colonization patterns, although the development of epiphytic communities is a dynamic process influenced by several factors, including nutrient availability, the ability to synthesize and secrete extracellular material, the competition among species and the influence of grazers on individual colonizers. The process may be drastically impacted by global warming and ocean acidification due to the increasing atmospheric levels of CO2. The impact of such global stressors on benthic ecosystems, especially on the primary microphytobenthic assemblages, is still poorly investigated, and may have deleterious consequences for the benthic successions. In this review, we analyze the adhesion patterns of marine microorganisms according to their surface features and the effects of global changes on critical pioneer colonizers, such as the benthic diatoms. The results are remarkable, as they highlight emergent concerns in ecosystem conservation and the prediction of benthic communities.
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Jesus, Bruno, Thierry Jauffrais, Erik C. L. Trampe, Johannes W. Goessling, Charlotte Lekieffre, Anders Meibom, Michael Kühl und Emmanuelle Geslin. „Kleptoplast distribution, photosynthetic efficiency and sequestration mechanisms in intertidal benthic foraminifera“. ISME Journal 16, Nr. 3 (11.10.2021): 822–32. http://dx.doi.org/10.1038/s41396-021-01128-0.
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AbstractForaminifera are ubiquitously distributed in marine habitats, playing a major role in marine sediment carbon sequestration and the nitrogen cycle. They exhibit a wide diversity of feeding and behavioural strategies (heterotrophy, autotrophy and mixotrophy), including species with the ability of sequestering intact functional chloroplasts from their microalgal food source (kleptoplastidy), resulting in a mixotrophic lifestyle. The mechanisms by which kleptoplasts are integrated and kept functional inside foraminiferal cytosol are poorly known. In our study, we investigated relationships between feeding strategies, kleptoplast spatial distribution and photosynthetic functionality in two shallow-water benthic foraminifera (Haynesina germanica and Elphidium williamsoni), both species feeding on benthic diatoms. We used a combination of observations of foraminiferal feeding behaviour, test morphology, cytological TEM-based observations and HPLC pigment analysis, with non-destructive, single-cell level imaging of kleptoplast spatial distribution and PSII quantum efficiency. The two species showed different feeding strategies, with H. germanica removing diatom content at the foraminifer’s apertural region and E. williamsoni on the dorsal site. All E. williamsoni parameters showed that this species has higher autotrophic capacity albeit both feeding on benthic diatoms. This might represent two different stages in the evolutionary process of establishing a permanent symbiotic relationship, or may reflect different trophic strategies.
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Car, Ana, Cüneyt Nadir Solak, Stijepo Ljubimir, Aydin Kaleli, Iris Dupčić Radić und Dubravka Hafner. „Comparison of benthic diatom community structures on natural and artificial substrates in marine lake (Adriatic Sea)“. Acta Adriatica 62, Nr. 1 (26.07.2021): 21–44. http://dx.doi.org/10.32582/aa.62.1.1.
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In this study, the diatoms of three alternative habitats (epilithon, epiphyton and artificial sub-strate) were compared to understand the differences in composition on artificial and natural sub-strates. For this purpose, the samples were collected weekly between 11th August and 2nd Septem-ber 2016 at a sampling site in a shallow marine lake, Mrtvo More (Dead Sea) on Lokrum Island near Dubrovnik (South Adriatic, Croatia). In addition to detailed light microscopic analysis, ultrastructural analysis of benthic diatoms from Lake Mrtvo More was performed for the first time using scanning electron microscopy (SEM). A total of 97 taxa were identified in 12 samples. Cocconeis scutellum Ehrenberg and Halamphora coffeiformis (C.Agardh) Levkov were the most frequent taxa in the samples. Shannon-Wiener diver-sity index (H’) values varied from 1.78 (in September on Padina sp.) to 4.52 (in August on glass). According to non-metric multidimensional scaling ordination, there were two groups: epilithon and artificial glass substrate as Group1 and macroalgae as Group2. The results of the analysis showed that the diatom communities developing on artificial sub-strates accurately correspond to the diatom community of a rock substrate and thus can be used as a representative alternative tool for studies of epilithic diatoms in further experiments.
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Duan, Dong Xia, Cong Guo Lin und Guang Zhou Liu. „Influence of Subtilisin on Mussel (Mytilus edulis) Byssus Deposition and Diatom (Navicula sp.) Settlement“. Applied Mechanics and Materials 295-298 (Februar 2013): 69–73. http://dx.doi.org/10.4028/www.scientific.net/amm.295-298.69.
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Biofouling organisms secrete adhesive polymers to settle themselves on man-made substrata in the marine environment. Mussels (Mytilus edulis) and diatom (Navicula sp.) are both major marine biofoulers. They attach tenaciously to a wide variety of submerged surfaces by virtue of byssus and extracellular polymer substances, respectively. The aim of this study is to evaluate the antifouling potential of the serine protease subtilisin on mussels and benthic diatoms. The effects of enzyme concentration, treatment duration and application time were tested on byssus deposition. The results showed that subtilisin effectively prevented the byssus formation. The reduction rate of byssal plaques was dependent on enzyme concentration and treatment duration. The byssal plaques of Mytilus edulis became progressively less sensitive to hydrolysis as they cured. Attached diatoms on polystyrene substrate were effectively removed by subtilisin.
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Al-Handal, Adil Y., Anders Torstensson und Angela Wulff. „Revisiting Potter Cove, King George Island, Antarctica, 12 years later: new observations of marine benthic diatoms“. Botanica Marina 65, Nr. 2 (23.02.2022): 81–103. http://dx.doi.org/10.1515/bot-2021-0066.
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Abstract Continuous observations of Antarctic benthic diatoms are necessary to detect changes in species composition and biodiversity that may result from environmental changes. The present work provides a systematic list of benthic diatoms from Potter Cove (62.03°S 58.35°W) collected during summer 2015. The new findings are compared with observations made 12 years ago (summer 2003). In total, 80 taxa were found, similar to that encountered earlier, but 17 species (21% of the total species number) were not observed in 2003, and 26 species (31%) of those reported in 2003 did not appear in 2015. The dominant species in 2003 and 2015 was the large epipelic and cosmopolitan Gyrosigma fasciola. Most of the species either newly observed in the present study, or absent in the present study but observed previously, occurred either rarely or very rarely. Gyrosigma arcuatum and Pleurosigma diversestriatum were newly observed in 2015 and not previously reported from polar regions. This study provides systematic and ecological information on all taxa encountered and is illustrated with light microscopy and scanning electron microscopy (SEM) images. We emphasize that ice-inhabiting and other benthic diatoms should be included when considering the biodiversity of polar diatoms. Thus, we hope that the present study will add a piece to the puzzle of climate change effects on the benthic diatoms in this vulnerable region and will complement earlier published species records in the area.
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Blaginina, Anastasiia, Daria Balycheva, Ekaterina Miroshnichenko, Larisa Ryabushko, Sergey Kapranov, Sophia Barinova und Denis Lishaev. „Does the Elemental Composition of Rock Surfaces Affect Marine Benthic Communities of Diatoms and Cyanobacteria?“ Journal of Marine Science and Engineering 11, Nr. 8 (09.08.2023): 1569. http://dx.doi.org/10.3390/jmse11081569.
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Rocky seabeds, as an integral part of ecotopes in marine ecosystems, are actively inhabited by diatoms and cyanobacteria. It is currently unknown whether the element contents in the surface layer of seabed rocks affect the epilithon species composition and abundance in microphytobenthos communities in the sea. The results of this study on the rock surface element composition and correlation analysis of the element contents with the abundance of epilithon diatoms and cyanobacteria in three bays in Sevastopol (Black Sea) are presented. Ca, Fe, and Si were the major elements with the largest weight fraction in the rock surface layer. Using cluster analysis, the differentiation of samples in the content and distribution of these three elements was shown. In total, 63 taxa of diatoms and 20 species of cyanobacteria were found, with their abundance ranging from 14,000 to 17,6000 cells/cm2 and from 12,000 to 1,198,000 cells/cm2, respectively. In general, it was found that the elemental composition of the rock surface is not a decisive factor affecting the total abundance of the benthic diatom and cyanobacterial communities as no strong correlations with any element contents were observed. However, when analyzing the abundance of populations of certain largely non-dominant species, the majority of diatoms showed noticeable (r = 0.5–0.7) to very high (r = 0.9–0.99) correlations with Fe. The highest positive correlations were noted for the diatoms Bacillaria paxillifer and Navicula directa with Fe. For the cyanobacteria Chroococcus minutus, Pseudanabaena minima, and Spirulina subsalsa, strong positive correlations with Ca and negative correlations with Si were observed. The correlations with Fe were very strong and negative for Lyngbya confervoides and strong and positive for Kamptonema laetevirens and Phormidium holdenii.
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Hermawati, Selia, Hawis Madduppa, Mohammad Mukhlis Kamal, Rahmat Kurnia und Rita Rachmawati. „Diatom communities in marine protected areas in the coral reefs in Lombok, Indonesia, using aqueous and sedimentary environmental DNA (eDNA)“. E3S Web of Conferences 442 (2023): 01023. http://dx.doi.org/10.1051/e3sconf/202344201023.
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Diatom has a specific response to particular ecological conditions. They live both planktonic and benthic, which is usually the diversity that has only been documented by microscopic. The information about the diversity of Diatoms is critical as a baseline study for biomonitoring. Thus, in this study, we applied environmental DNA through a next-generation sequencing method to analyze planktonic and benthic communities of Diatom in marine protected areas in Lombok Waters, Indonesia. The result shows that benthic Diatom has more richness than planktonic but lacks significance between spatial. In our study, we detected 25 species of Diatom in West and East Lombok. Diatom from sediment samples has more richness than water, with four species only found in the Water samples and 18 species in the sediment samples. Three species were found both in the water and sediment samples. The highest abundance in the Stramenopiles clades is Diatom. Relative abundance of diatom about 12% to 23.91% from total micro eukaryotic or about 85.71%tol 86.14% from total Stramenopiles clades for East Lombok and West Lombok, respectively. Limitations of the genetic reference database, especially for tropical causes, restricted the determination of genetically identified sequence types at both genus and species levels.
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Boelts, Hannah P., Yadira Ibarra und Clive Hayzelden. „The influence of benthic diatoms on the textures of carbonate-coated grains from a fluvial tufa spring in northern California“. Journal of Sedimentary Research 90, Nr. 11 (30.11.2020): 1601–13. http://dx.doi.org/10.2110/jsr.2020.74.
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ABSTRACT Diatoms are common in terrestrial freshwater carbonate environments, but their influence on the resulting carbonate texture and porosity remains unquantified. This study investigates the effect of diatoms on the textural variability and syndepositional porosity of spring-associated carbonate coated grains from a freshwater spring in Henry Cowell State Park, northern California, USA. Carbonate coated grains (n = 60) were collected from the distal-most pool of the spring (∼ 300 m from the spring source) and the porosity of the 1 cm diameter fraction (n = 20) was determined using the ImageJ software by adjusting the threshold size for pores > 1000 μm2. Results reveal a strong positive correlation between the number of pores and the number of diatoms examined in each coated grain (r = 0.77). There is a moderate positive relationship between the length of the largest diatom and the minor-axis diameter of a best-fit ellipse of its corresponding pore (r = 0.60). The total pore area for pores associated with at least one diatom was significantly greater than the total pore area of pores that did not enclose diatom frustules (t = 1.80, p < 0.05). Textural observations show that fine-grained laminated textures contain fewer diatoms than the porous textures, suggesting that diatoms disrupt lamination continuity by introducing pore space. These findings have implications for the influence of diatoms on the syndepositional porosity of carbonate rocks from the Cretaceous to Recent and may help explain textural differences between modern marine carbonate microbialites and their Precambrian counterparts.
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Glaviano, Francesca, Nadia Ruocco, Emanuele Somma, Giuseppe De Rosa, Virginia Campani, Pasquale Ametrano, Davide Caramiello, Maria Costantini und Valerio Zupo. „Two Benthic Diatoms, Nanofrustulum shiloi and Striatella unipunctata, Encapsulated in Alginate Beads, Influence the Reproductive Efficiency of Paracentrotus lividus by Modulating the Gene Expression“. Marine Drugs 19, Nr. 4 (17.04.2021): 230. http://dx.doi.org/10.3390/md19040230.
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Physiological effects of algal metabolites is a key step for the isolation of interesting bioactive compounds. Invertebrate grazers may be fed on live diatoms or dried, pelletized, and added to compound feeds. Any method may reveal some shortcomings, due to the leaking of wound-activated compounds in the water prior to ingestion. For this reason, encapsulation may represent an important step of bioassay-guided fractionation, because it may assure timely preservation of the active compounds. Here we test the effects of the inclusion in alginate (biocompatible and non-toxic delivery system) matrices to produce beads containing two benthic diatoms for sea urchin Paracentrotus lividus feeding. In particular, we compared the effects of a diatom whose influence on P. lividus was known (Nanofrustulum shiloi) and those of a diatom suspected to be harmful to marine invertebrates, because it is often present in blooms (Striatella unipunctata). Dried N. shiloi and S. unipunctata were offered for one month after encapsulation in alginate hydrogel beads and the larvae produced by sea urchins were checked for viability and malformations. The results indicated that N. shiloi, already known for its toxigenic effects on sea urchin larvae, fully conserved its activity after inclusion in alginate beads. On the whole, benthic diatoms affected the embryogenesis of P. lividus, altering the expression of several genes involved in stress response, development, skeletogenesis and detoxification processes. Interactomic analysis suggested that both diatoms activated a similar stress response pathway, through the up-regulation of hsp60, hsp70, NF-κB, 14-3-3 ε and MDR1 genes. This research also demonstrates that the inclusion in alginate beads may represent a feasible technique to isolate diatom-derived bioactive compounds.
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Vélez-Agudelo, Camilo, und Marcela A. Espinosa. „Benthic diatoms in relation to environmental factors in an allochthonous river from Patagonia, Argentina“. Marine and Freshwater Research 72, Nr. 9 (2021): 1340. http://dx.doi.org/10.1071/mf20249.
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Natural and human pressures increasingly threatening the biodiversity and water resources of dryland rivers. Fluvial environments of Patagonia harbour high diatom diversity, but their management value is overlooked. The aim of this study is to explore the diatom distribution in surface sediments of the Chubut River and evaluate their relationship with environmental variables. In total, 243 diatom taxa were identified in 16 littoral zone sites. The physical and chemical variables independently explained the variance in diatom data, whereas sediment texture had a low influence. Conductivity, major ions (HCO3–, Cl–, SO42–, Na+, K+, Ca2+ and Mg2+) and pH were the main environmental drivers explaining the diatom composition. As the highlighted variables increased near the mouth, so did the relative abundances of marine–brackish taxa such as Amphora copulatoides, Sarcophagodes alfred-wegeneri, Nitzschia fonticola and Tryblionella apiculata. Meanwhile, the presence of high pollution-tolerant diatoms can be put forward to explain the river health deterioration towards downstream areas. The marine–brackish taxa found at freshwater sites reflect a weak tidal influence in the estuary compared with other coastal systems of Patagonia. This study provides valuable information to test the hypothesis on the ecological status of aquatic resources and the potential effects of climatic and hydrological changes in the area.
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Siqueiros Beltrones, David Alfaro, Yuriko Jocselin Martínez und Francisco Omar López-Fuerte. „Epiphytic Diatoms from the Central Region of the Gulf of California: Floristics and Biogeographic Remarks“. Diversity 15, Nr. 4 (02.04.2023): 510. http://dx.doi.org/10.3390/d15040510.
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The ecological significance of benthic diatom taxocoenoses in marine ecosystems renders them a suitable reference when making decisions on conservation, as well as ecological and biogeographical issues. This study focuses on floristics of epiphytic diatoms of macroalgae from the central region of the Gulf of California and their biogeographical affinities. Based on current floristics for benthic diatoms of the Mexican NW, it was hypothesized that species richness would be higher for the central gulf (transitional) than for the tropical Revillagigedo Archipelago. Additionally, it was hypothesized that it would be composed mainly of common taxa of the region, with tropical and temperate components. Likewise, it was hypothesized that Mastogloia (tropical) would include less taxa and Lyrella would include more taxa in the transitional central gulf. The diatom flora yielded 333 taxa and 101 genera, and out of which the best represented were Navicula with 29 taxa, Amphora (27), Cocconeis (25), Nitzschia (24), Diploneis (19), Achnanthes (13), Halamphora (14), Fallacia (10), Lyrella (9), and Mastogloia (8), adding up to 53% of the total. The inspected diatom taxocoenosis included mostly taxa commonly distributed in the Mexican NW, albeit with 16 new records. This, plus the high species richness, as well as the proportions of selected taxa depicting this diatom taxocoenosis as being of transitional biogeographical affinity, back the posed hypotheses.
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Klapper, Franziska, Sien Audoor, Wim Vyverman und Georg Pohnert. „Pheromone Mediated Sexual Reproduction of Pennate Diatom Cylindrotheca closterium“. Journal of Chemical Ecology 47, Nr. 6 (29.04.2021): 504–12. http://dx.doi.org/10.1007/s10886-021-01277-8.
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AbstractBenthic diatoms dominate primary production in marine subtidal and intertidal environments. Their extraordinary species diversity and ecological success is thought to be linked with their predominantly heterothallic sexual reproduction. Little is known about pheromone involvement during mating of pennate diatoms. Here we describe pheromone guided mating in the coastal raphid diatom Cylindrotheca closterium. We show that the two mating types (mt+ and mt−) have distinct functions. Similar to other benthic diatoms, mt+ cells are searching for the mt− cells to pair. To enhance mating efficiency mt− exudes an attraction pheromone which we proved by establishing a novel capillary assay. Further, two more pheromones produced by mt− promote the sexual events. One arrests the cell cycle progression of mt+ while the other induces gametogenesis of mt+. We suggest that C. closterium shares a functionally similar pheromone system with other pennate diatoms like Seminavis robusta and Pseudostaurosira trainorii which synchronize sexual events and mate attraction. Remarkably, we found no evidence of mt+ producing pheromones, which differentiates C. closterium from other pennates and suggests a less complex pheromone system in C. closterium.
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Al-Saedy, Rehab. „Tolerance of Benthic Diatoms to Severe Environmental Stress: A Case Study in Shatt Al-Arab River, Basrah, Iraq“. Biological and Applied Environmental Research 5, Nr. 2 (07.07.2021): 222–47. http://dx.doi.org/10.51304/baer.2021.5.2.222.
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The present work aims at investigating the ability of diatoms to re-establish their community after a severe environmental stress such desiccation. Diatoms were subjected to extreme environmental stress to observe their survival capability. Samples of sediment were collected from three sites, Maqal, Abu Flos and Al-Faw along the course of Shatt Al-Arab river. Different temperature regimes were implemented for testing the ability of diatoms to recover desiccation. Experiments were performed at various temperatures, 10, 15, 20, 25, 30, 35 and 40 ℃. A total of 67 diatom species were identified and included freshwater forms (25%), brackish water forms (25%) and marine species (26%), as well as 24% of taxa with undefined ecological preferences. The recovery rate of diatom species at all sites appeared to be rather similar. 40%, 38% and 37% of all taxa encountered were able to recover desiccation at sites 1, 2 and 3, respectively. Recovering ability of those species varies with variable temperature. Favourable temperature for most species to regrow ranged between 15 and 25 oC. Nitzschia palea exhibited the maximum growth rate at all temperatures (10-35 oC). 32% of all epiphytic species encountered were able to recover at 20 oC. Five species: Craspedostauros britannicus, Nitzschia invisitata, Pinnularia quadratarea, Simonsenia sp. and Tryblionella plana were not previously reported in Iraq and considered as new to the region. A new species, Synedropsis abuflosensis, was found. The outcome of the present work clearly indicates that some species of diatoms can recover after exposure to sever environmental stress.
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Wu, Yaping, Furong Yue, Juntian Xu und John Beardall. „Differential photosynthetic responses of marine planktonic and benthic diatoms to ultraviolet radiation under various temperature regimes“. Biogeosciences 14, Nr. 22 (14.11.2017): 5029–37. http://dx.doi.org/10.5194/bg-14-5029-2017.
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Abstract. We studied the photophysiological responses to ultraviolet radiation (UVR) of two diatoms, isolated from different environmental niches. Both species showed the highest sensitivity to UV radiation under relatively low temperature, while they were less inhibited under moderately increased temperature. Under the highest temperature applied in this study, the benthic diatom Nitzschia sp. showed minimal sensitivity to UV radiation, while inhibition of the planktonic species, Skeletonema sp., increased further compared with that at the growth temperature. These photochemical responses were linked to values for the repair and damage processes within the cell; higher damage rates and lower repair rates were observed for Skeletonema sp. under suboptimal temperature, while for Nitzschia sp., repair rates increased and damage rates were stable within the applied temperature range. Our results suggested that the response of the microalgae to UV radiation correlated with their niche environments, the periodic exposure to extreme temperatures promoting the resistance of the benthic species to the combination of high temperature and UV radiation.
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Siqueiros-Beltrones, D. A. „DIATOMEAS BENTÓNICAS ASOCIADAS A TROMBOLITOS VIVOS“. CICIMAR Oceánides 21, Nr. 1-2 (31.12.2006): 113. http://dx.doi.org/10.37543/oceanides.v21i1-2.30.
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Se determinó el primer elenco florístico de diatomeas asocia das a trombolitos vivos (protrombolitos). Estos sustratos que exhiben condiciones particulares de estabilidad, fueron descubiertos en playas de la Ensena da de La Paz, B.C.S. y representan un nuevo sustrato para el desarrollo de diatomeas bentónicas marinas. Se examinaron fragmentos de protrombolitos recolectados mensualmente, de agosto a noviembre de 2005, en cuatro sitios de la Ensenada. La envoltura de los protrombolitos consiste en un complejo de cianofitas: Microcoleus chthonoplastes, Oscillatoria limosa/Lyngbia aestuarii y otras formas filamentosas. Se identificaron 150 taxa de diatomeas, principalmente formas pennadas. La presencia de ciertos taxa evidencia la influencia de los manglares y ambientes hipersalinos aledaños. Aunque la composición de especies no difiere de otras asociaciones de la región, los taxa dominantes son distintos; los más frecuentes son: Mastogloia pumila (Grun.) Cleve, Mastogloia obliqua Hagelstein, Navicula formenterae Cleve, Nitzschia frustulum var. perminuta Grunow, Nitzschia scalpelliformis (Grun.) Grunow, Nitzschia sigma (Kütz.) W. Smith, Psammodyction constricta (Kütz.) Ralfs, Rhopalodia gibberula (Ehr.) O. Müller, Seminavis sp. 1. La riqueza de especies es considerada alta, dada la estabilidad y homogeneidad del sistema protrombolítico. Benthic diatoms associated to living thrombolites The first floristic account of benthic diatoms associated to recent (living) thrombolites or protrombolites was determined. These sedimentary formations generated by cyanophytes that exhibit particular conditions of stability were discovered in beaches of Ensenada de La Paz. These represent new substrata for the growth of marine benthic diatoms. Fragments of pro-thrombolites collected monthly from August to November in four sites of the Ensenada were examined. The pro-thrombolite cover consisted of a cyanophyte complex where Microcoleus chthonoplastes, Oscillatoria limosa/Lyngbia aestuarii, and other filamentous forms are the main components. A total of 150 diatom taxa were identified, mainly pennate forms. The presence of certain taxa shows the influence of nearby mangroves and hypersaline environments. Although the species composition does not seem to differ from other assemblages in the region, dominant taxa are different. The most frequent taxa were: Mastogloia pumila (Grun.) Cleve, Mastogloia obliqua Hagelstein, Navicula formenterae Cleve, Nitzschia frustulum var. perminuta Grunow, Nitzschia scalpelliformis (Grun.) Grunow, Nitzschia sigma (Küt z.) W. Smith, Psammodyction constricta (Kütz.) Ralfs, Rhopalodia gibberula (Ehren berg) O. Müller, Seminavis sp. 1. The species richness is high considering the stability and homogeneity of the pro-thrombolithic system.
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Siqueiros-Beltrones, D. A. „DIATOMEAS BENTÓNICAS ASOCIADAS A TROMBOLITOS VIVOS“. CICIMAR Oceánides 21, Nr. 1-2 (31.12.2006): 113. http://dx.doi.org/10.37543/oceanides.v21i1-2.30.
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Se determinó el primer elenco florístico de diatomeas asocia das a trombolitos vivos (protrombolitos). Estos sustratos que exhiben condiciones particulares de estabilidad, fueron descubiertos en playas de la Ensena da de La Paz, B.C.S. y representan un nuevo sustrato para el desarrollo de diatomeas bentónicas marinas. Se examinaron fragmentos de protrombolitos recolectados mensualmente, de agosto a noviembre de 2005, en cuatro sitios de la Ensenada. La envoltura de los protrombolitos consiste en un complejo de cianofitas: Microcoleus chthonoplastes, Oscillatoria limosa/Lyngbia aestuarii y otras formas filamentosas. Se identificaron 150 taxa de diatomeas, principalmente formas pennadas. La presencia de ciertos taxa evidencia la influencia de los manglares y ambientes hipersalinos aledaños. Aunque la composición de especies no difiere de otras asociaciones de la región, los taxa dominantes son distintos; los más frecuentes son: Mastogloia pumila (Grun.) Cleve, Mastogloia obliqua Hagelstein, Navicula formenterae Cleve, Nitzschia frustulum var. perminuta Grunow, Nitzschia scalpelliformis (Grun.) Grunow, Nitzschia sigma (Kütz.) W. Smith, Psammodyction constricta (Kütz.) Ralfs, Rhopalodia gibberula (Ehr.) O. Müller, Seminavis sp. 1. La riqueza de especies es considerada alta, dada la estabilidad y homogeneidad del sistema protrombolítico. Benthic diatoms associated to living thrombolites The first floristic account of benthic diatoms associated to recent (living) thrombolites or protrombolites was determined. These sedimentary formations generated by cyanophytes that exhibit particular conditions of stability were discovered in beaches of Ensenada de La Paz. These represent new substrata for the growth of marine benthic diatoms. Fragments of pro-thrombolites collected monthly from August to November in four sites of the Ensenada were examined. The pro-thrombolite cover consisted of a cyanophyte complex where Microcoleus chthonoplastes, Oscillatoria limosa/Lyngbia aestuarii, and other filamentous forms are the main components. A total of 150 diatom taxa were identified, mainly pennate forms. The presence of certain taxa shows the influence of nearby mangroves and hypersaline environments. Although the species composition does not seem to differ from other assemblages in the region, dominant taxa are different. The most frequent taxa were: Mastogloia pumila (Grun.) Cleve, Mastogloia obliqua Hagelstein, Navicula formenterae Cleve, Nitzschia frustulum var. perminuta Grunow, Nitzschia scalpelliformis (Grun.) Grunow, Nitzschia sigma (Küt z.) W. Smith, Psammodyction constricta (Kütz.) Ralfs, Rhopalodia gibberula (Ehren berg) O. Müller, Seminavis sp. 1. The species richness is high considering the stability and homogeneity of the pro-thrombolithic system.
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Sapozhnikov, Ph V., A. I. Salimon, A. M. Korsunsky, O. Yu Kalinina, F. S. Senatov, E. S. Statnik und Ju Cvjetinovic. „Features of formation of colonial settlements of marine benthic diatoms on the surface of synthetic polymer“. Marine Biological Journal 5, Nr. 2 (30.06.2020): 88–104. http://dx.doi.org/10.21072/mbj.2020.05.2.08.
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The topic of interactions between plastic and natural communities is now more relevant than ever before. Gradual accumulation of artificial polymer products and their fragments in the natural environment has reached a level at which it is already impossible to ignore the affect of these materials on living organisms. First and foremost, microorganism colonies inhabiting different biotopes, both aquatic and terrestrial, have been affected. These species are at the front-end of interaction with plastic, including those present in marine ecosystems. Nevertheless, in order to understand these processes, it is necessary to take into account several aspects of such interactions: the impact of different types of plastic on microbial community through the release of their decomposed products into the environment, the forms of plastic usage by microorganisms themselves, including mechanisms for surface colonization, as well as possible biodegradation processes of polymers due to the actions of microorganisms. At the same time, types of plastic may differ not only in mechanical strength, but also in their resistance to biodegradation caused by microorganisms. Experiments with surface colonization of types of plastic, which are different in composition and mechanical strength, provide a wide range of results that are not just relevant for understanding modern natural processes involving plastic: these results are also important for application in certain areas of technology development (for example, when creating composite materials). In particular, researches into the forms and mechanisms of sustainable colonization of particularly strong polymers by diatoms from natural communities are of great interest. Due to the fouling of surface of particularly strong synthetic polymers by diatoms, it is possible to form a single diatom-polymeric composite with general properties being already substantially different from those of the polymer itself. For example, when a polymer is fouled with diatoms that are firmly held on its surface due to physiological mechanisms that ensure their reliable fixation, total surface area of the composite increases by 2–3 orders of magnitude compared with this of bare polymer. Such composites and their properties are formed due to mechanisms of substrate colonization used by diatoms from natural marine cenoses – during the transfer of these mechanisms to a new material being prospective for diatom settlement. The practical applications of these composites lie in the sphere of heat and sound insulation, as well as in the field of creating prosthetic tissues for bone operations. In our experiments, we tracked the sequence of development of a stable composite when diatoms colonized the surface of samples of a particularly strong synthetic polymer being resistant to corrosion. In this case, the sample population process took place on the basis of colonies formed in accumulative cultures from the natural marine environment. Samples of ultra-high molecular weight polyethylene (UHMWPE) with a smooth and porous surface structure (with an open cell, bulk porosity up to 80 %) were colonized by diatoms Karayevia amoena (Hust.) Bukht., 2006, Halamphora coffeaeformis (C. Agardh) Levkov, 2009, and Halamphora cymbifera (W. Greg.) Levkov, 2009. These laboratory experiments lasted for three weeks. Accumulative microphyte cultures, on the basis of which the experiments were conducted, were obtained from the Baltic Sea (Baltiysk area, Russia) and the Arabian Sea (Mumbai area, India). The types and stages of development of colonial settlements on various elements of the frontal surface microrelief and in the underlying caverns were studied using a scanning electron microscope on samples subjected to stepwise thermal drying. Individual cells of K. amoena, H. coffeaeformis, and H. cymbifera, their chain-like aggregates, and outstretched colonial settlements occupied varying in degree non-homogeneous microrelief surface elements, forming structures with a thickness of 1–2 layers with an average settlement height of 1–1.3 single specimen height. K. amoena cells were tightly fixed to the polymer substrate using the pore apparatus of the flap of the frustule. Observations using scanning electron microscope revealed shell imprints on the substrate, which were signs of a polymer substrate introduction into hypotheca areoles. The spread mechanisms of diatoms of three mentioned species on various elements of UHMWPE surface were explored, as well as the formation of the characteristic elements of colonial settlements, including for K. amoena – consecutively in the form of “pots” and spheres, by means of interaction with polymer surface and its extension with the increase in the number of tightly attached cells in the colonial settlement.
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Vermeulen, Simon, Gilles Lepoint und Sylvie Gobert. „Processing samples of benthic marine diatoms from Mediterranean oligotrophic areas“. Journal of Applied Phycology 24, Nr. 5 (29.12.2011): 1253–60. http://dx.doi.org/10.1007/s10811-011-9770-4.
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Mejdandžić, Maja, Tomislav Ivanković, Martin Pfannkuchen, Jelena Godrijan, Daniela Marić Pfannkuchen, Jasna Hrenović und Zrinka Ljubešić. „Colonization of diatoms and bacteria on artificial substrates in the northeastern coastal Adriatic Sea“. Acta Botanica Croatica 74, Nr. 2 (01.10.2015): 407–22. http://dx.doi.org/10.1515/botcro-2015-0030.
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AbstractEvery surface that is immersed in seawater becomes rapidly covered with an unavoidable biofilm. Such biofilm formation, also known as fouling, is a complex multistage process and not yet thoroughly investigated. In this study, the succession of diatoms and bacteria was investigated during a one month exposure on an artificial substrate of plexiglass (polymer of methyl methacrylate) mounted above the seafloor at a depth of 5 m. For biofilm analyses, the fouling was investigated using selective agar plates, epifluorescence, light and electronic microscopy, as well as high performance liquid chromatography (HPLC) pigment analysis. During biofilm development, the abundance of all biofilm components increased and reached maximum values after a one month exposure. In the bacterial community, heterotrophic marine bacteria were dominant and reached 1.96 ± 0.79 × 104colony forming units (CFU) cm-2. Despite the fact that faecal coliforms and intestinal enterococci were detected in the water column, faecal coliforms were not detected in the biofilm and intestinal enterococci appeared after one month of exposure but in the negligible number of 60 ± 10 CFU cm-2. The phototrophic component of the biofilm was dominated by diatoms and reached a concentration of 6.10 × 105cells cm-2, which was supported by pigment analysis with fucoxanthin as dominant pigment in a concentration up to 110 ng cm-2. The diatom community was dominated by Cylindrotheca closterium and other pennate benthic diatoms. A detailed taxonomic analysis by electronic microscopy revealed 30 different taxa of diatoms. The study confirmed that a plexiglass surface in a marine environment is susceptible to biofouling within 30 days of contact. Furthermore, the co lonization process sequence firstly involved bacteria and cyanobacteria, and secondly diatoms, which together formed a primary biofilm in the sea.
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Romero, Oscar E., Simon Ramondenc und Gerhard Fischer. „A 2-decade (1988–2009) record of diatom fluxes in the Mauritanian coastal upwelling: impact of low-frequency forcing and a two-step shift in the species composition“. Biogeosciences 18, Nr. 5 (18.03.2021): 1873–91. http://dx.doi.org/10.5194/bg-18-1873-2021.
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Abstract. Eastern boundary upwelling ecosystems (EBUEs) are among the most productive marine regions in the world's oceans. Understanding the degree of interannual to decadal variability in the Mauritania upwelling system is crucial for the prediction of future changes of primary productivity and carbon sequestration in the Canary Current EBUE as well as in similar environments. A multiyear sediment trap experiment was conducted at the mooring site CBmeso (“Cape Blanc mesotrophic”, ca. 20∘ N, ca. 20∘40′ W) in the highly productive coastal waters off Mauritania. Here, we present results on fluxes of diatoms and the species-specific composition of the assemblage for the time interval between March 1988 and June 2009. The temporal dynamics of diatom populations allows the proposal of three main intervals: (i) early 1988–late 1996, (ii) 1997–1999, and (iii) early 2002–mid 2009. The Atlantic Multidecadal Oscillation (AMO) appears to be an important driver of the long-term dynamics of diatom population. The long-term AMO-driven trend is interrupted by the occurrence of the strong 1997 El Niño–Southern Oscillation (ENSO). The extraordinary shift in the relative abundance of benthic diatoms in May 2002 suggests the strengthening of offshore advective transport within the uppermost layer of filament waters and in the subsurface and in deeper and bottom-near layers. It is hypothesized that the dominance of benthic diatoms was the response of the diatom community to the intensification of the slope and shelf poleward undercurrents. This dominance followed the intensification of the warm phase of AMO and the associated changes of the Atlantic Meridional Overturning Circulation. Transported valves (siliceous remains) from shallow Mauritanian coastal waters into the bathypelagic should be considered for the calculation and model experiments of bathy- and pelagic nutrients budgets (especially Si), the burial of diatoms, and the paleoenvironmental signal preserved in downcore sediments. Additionally, our 1988–2009 data set contributes to the characterization of the impact of low-frequency climate forcings in the northeastern Atlantic and will be especially helpful for establishing the scientific basis for forecasting and modeling future states of the Canary Current EBUE and its decadal changes.
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Lei, Yanli, Chengchun Li, Tiegang Li und Zhimin Jian. „The Effect of Temperature and Food Concentration On Ingestion Rates of Quinqueloculina Seminula On the Diatom Nitzschia Closterium“. Journal of Foraminiferal Research 49, Nr. 1 (11.01.2019): 3–10. http://dx.doi.org/10.2113/gsjfr.49.1.3.
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Abstract The majority of sediment-dwelling foraminifera are thought to be deposit feeders. They use their reticulopodia to gather sediment with associated algae, organic detritus, and bacteria. Uptake of diatoms by foraminifera have been observed but rarely quantified. We measured the clearance (gathering) rate and ingestion rate of diatoms by the common benthic foraminifer Quinqueloculina seminula using Nitzschia closterium as prey under laboratory culture conditions. Grazing experiments were performed to evaluate the effects of temperature (at 12, 15, 18, 21, and 24°C) and food availability (10 to 800 cells mm−2) on uptake rates of diatoms. The clearance rates, estimated from the disappearance of food items, were variable (0.59–4.4 mm2 foram−1 h−1) and did not show a clear relationship with food availability. The maximum clearance rates increased from 1.80 ± 0.21 to 2.69 ± 0.32 mm2 foram−1 h−1 when temperature increased from 12 to 18°C and decreased to 2.28 ± 0.25 mm2 foram−1 h−1 at 24°C. Ingestion rates varied from 1.0 to 43 × 103 diatoms foram−1 h−1, following a hyperbolic response to food concentrations at all experimental temperatures. The maximum individual ingestion rates increased from 842 ± 180 to 1648 ± 480 (mean ± SE) cells foram−1 h−1 and then decreased to 316 ± 54 cells foram−1 h−1 as temperature increased from 12 to 24°C. Experimental results revealed that 12–18°C was the optimal temperature range for Q. seminula feeding for specimens adapted to local conditions. Our study indicates that Q. seminula plays an ecological role by feeding upon benthic diatoms in marine benthic ecosystems.
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Martin, Marcela V., Christina Gebühr, Daniel O. Mártire und Karen H. Wiltshire. „Characterization of a humic acid extracted from marine sediment and its influence on the growth of marine diatoms“. Journal of the Marine Biological Association of the United Kingdom 94, Nr. 5 (08.04.2014): 895–906. http://dx.doi.org/10.1017/s0025315414000368.
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Due to the input of humic substances from freshwater run-off into the marine habitat, the influences of such substances on marine organisms should not be neglected. We here investigate the effect of a humic acid (HA) extract from the North Sea, characterized by spectroscopic techniques and carboxylic and phenolic group content, on the growth of different algae. Two benthic pennate diatoms isolated from the Baltic Sea, Navicula ramosissima (C. Agardh) Cleve, 1895 and Entomoneis paludosa (W. Smith) Reimer, 1975, as well as two tychopelagic centric diatoms isolated from the North Sea, Melosira nummuloides C. Agardh, 1824 and Paralia sulcata (Ehrenberg) Cleve, 1873, were employed. The concentrations of pigments (fucoxanthin, diadinoxanthin, chlorophyll-a and β-carotene) and nutrients were also measured. Adding low concentrations of naturally humic substances (5.5 mg of C l−1) to the algae cultures resulted in enhanced growth rates compared to the control experiments, possibly due to the increase in the bioavailability of trace metals or other nutrients.
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LÓPEZ-FUERTE, FRANCISCO OMAR, DAVID A. SIQUEIROS-BELTRONES und LUCIEN VELEVA. „DIATOMS (BACILLARIOPHYTA) FROM ARTIFICIAL SUBSTRATES AND SEDIMENTS IN THE CARIBBEAN SEA OFF YUCATAN, MEXICO“. Phytotaxa 406, Nr. 1 (13.06.2019): 1. http://dx.doi.org/10.11646/phytotaxa.406.1.1.
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We provide a floristic and iconographic reference of benthic marine diatom taxa growing on various artificial substrate plates: fiber-glass, stainless steel, aluminum and copper, afixed to a subtidal beach, as well as of diatoms from the adjacent sediments. The sampling site is located 10 km off the beach of Puerto de Telchac, Yucatan, Mexico. The floristic survey comprises 161 diatom taxa, species and varieties, with six new records for Mexican waters with taxonomic, nomenclatural, and updated bibliographic information for each taxon. Twenty-five taxa were identified solely to genus level. The number of species per substrate was: fiberglass 102, sediments 76, aluminum 51, stainless steel 14, and copper 10. The resulting catalog gathers 267 images, with 137 scanning electron micrographs and 135 light micrographs. Fiber-glass plates showed the highest similarity to natural substrate, at 70% of the total taxa, while copper harbored only 6%.
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Lange, Priscila Kienteca, Ryszard Ligowski und Denise Rivera Tenenbaum. „Phytoplankton in the embayments of King George Island (Antarctic Peninsula): a review with emphasis on diatoms“. Polar Record 54, Nr. 2 (März 2018): 158–75. http://dx.doi.org/10.1017/s0032247418000232.
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ABSTRACTConsidering that phytoplankton assemblages are good bioindicators of environmental conditions, the sensitivity of the Western Antarctic Peninsula (WAP) to climate change, and the importance of some areas of its islands as Antarctic Specially Managed Areas, this work assembles published datasets on phytoplankton biodiversity and ecology in confined coastal areas (embayments) of King George Island, WAP. Over 33 years (1980–2013), 415 species from 122 genera have been identified to species level, being mostly diatoms (371 species), with 10 new species described with local material (6 diatoms, 4 cyanobacteria). The importance of diatoms was indicated by the frequent occurrence of Corethron pennatum, Pseudogomphonema kamtshaticum, and abundant benthic genera in the plankton (e.g. Navicula, Cocconeis). The increased contribution of dinoflagellates after 2010 suggests marked changes in the water column. Early-summer blooms differ between the bays' eastern and western shores, with terrestrial melting and wind-driven upwelling inducing the dominance of benthic species at eastern shores, whereas planktonic diatoms (Thalassiosira, Pseudo-nizschia, and Chaetoceros) are most abundant along western shores and central areas. The importance of an accurate identification of organisms that are becoming key ecological components of the region is discussed, as recent changes in the microflora may affect the entire marine food web.
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Brandini, Frederico P., und Luciano F. Fernandes. „Microalgae of the continental shelf off Paraná State, southeastern Brazil: a review of studies“. Revista Brasileira de Oceanografia 44, Nr. 1 (1996): 69–80. http://dx.doi.org/10.1590/s1413-77391996000100008.
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The paper reviews the taxonomic and ecological works on marine microalgae (phytoplankton and microphytobenthos) off Paraná State, Southeastern Brazil. Various studies refer to the taxonomy of benthic diatoms. Few descriptive field works in coastal and adjacent shelf waters contribute to the understanding of phytoplankton dynamics in coastal and shelf areas. Patterns of geographic distribution and changes in the phytoplankton community are described in relation to water masses and seasonal variations in the hydrographic regime. During summertime, when warm oligotrophic waters predominate over the shelf, the phytoplankton is nummerically dominated by small phytotlagellates, dinotlagellates, coccolithophorids and filaments of cyanobacteria. During wintertime, the abundance of micro-size diatoms over the shclf increase due to the dominance of cold nutrient-rich waters from the South Atlantic Central Water and wind-driven vertical circulation. The phytoplankton community off Paraná State may be classified into two categorics: the diatom-dominated coastal assemblage, mainly controlled by nutrient inputs from land drainage and ressuspension of bottom sediments, and the tlagellate-dominated shelf assemblage, more affectcd by the seasonality of local hydrographic regime.
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Sánchez Angulo, Leonardo, Karla Suzeth Trejo Berumen und Bertha Olivia Arredondo Vegaorcid.org. „Importancia nutrimental de la diatomea Odontella aurita para su aprobación como suplemento generalmente reconocido como alimento seguro (GRAS) en México“. RECURSOS NATURALES Y SOCIEDAD 8, Nr. 1 (2022): 15–38. http://dx.doi.org/10.18846/renaysoc.2022.08.08.01.0002.
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Diatoms are photosynthetic organisms that are distributed in different habitats. They are responsible for more than 50% of the primary productivity in marine ecosystems. Due to their high content of highly unsaturated fatty acids (HUFA) such as eicosapentaenoic acid (EPA ω3) and carotenoid pigments such as fucoxanthin, they are candidates for the prevention and regulation of human cardiovascular diseases. They have biotechnological interest in the food sector. In this review, we took as a study model the benthic diatom Odontella aurita, isolated from La Ribera, Baja California Sur, Mexico. We present the potential of this species has in terms of a nutritional level as a GRAS food (generally recognized as safe food), and as a viable alternative for a future commercialization.
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Zúñiga, Diana, Celia Santos, María Froján, Emilia Salgueiro, Marta M. Rufino, Francisco De la Granda, Francisco G. Figueiras, Carmen G. Castro und Fátima Abrantes. „Diatoms as a paleoproductivity proxy in the NW Iberian coastal upwelling system (NE Atlantic)“. Biogeosciences 14, Nr. 5 (13.03.2017): 1165–79. http://dx.doi.org/10.5194/bg-14-1165-2017.
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Abstract. The objective of the current work is to improve our understanding of how water column diatom's abundance and assemblage composition is seasonally transferred from the photic zone to seafloor sediments. To address this, we used a dataset derived from water column, sediment trap and surface sediment samples recovered in the NW Iberian coastal upwelling system. Diatom fluxes (2.2 (±5.6) 106 valves m−2 d−1) represented the majority of the siliceous microorganisms sinking out from the photic zone during all studied years and showed seasonal variability. Contrasting results between water column and sediment trap diatom abundances were found during downwelling periods, as shown by the unexpectedly high diatom export signals when diatom-derived primary production achieved their minimum levels. They were principally related to surface sediment remobilization and intense Minho and Douro river discharge that constitute an additional source of particulate matter to the inner continental shelf. In fact, contributions of allochthonous particles to the sinking material were confirmed by the significant increase of both benthic and freshwater diatoms in the sediment trap assemblage. In contrast, we found that most of the living diatom species blooming during highly productive upwelling periods were dissolved during sinking, and only those resistant to dissolution and the Chaetoceros and Leptocylindrus spp. resting spores were susceptible to being exported and buried. Furthermore, Chaetoceros spp. dominate during spring–early summer, when persistent northerly winds lead to the upwelling of nutrient-rich waters on the shelf, while Leptocylindrus spp. appear associated with late-summer upwelling relaxation, characterized by water column stratification and nutrient depletion. These findings evidence that the contributions of these diatom genera to the sediment's total marine diatom assemblage should allow for the reconstruction of different past upwelling regimes.
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Peng, Yan Lei, Cun Guo Lin und Li Wang. „The Preliminary Study on Antifouling Mechanism of Shark Skin“. Advanced Materials Research 79-82 (August 2009): 977–80. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.977.
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Biofouling, which is the result of marine organisms settling, attaching, and growing on submerged marine surfaces, is a usually-seeing phenomenon for the ocean-going ships and submarines. And, it can decrease the range, speed, and maneuverability of these vessels and increase the fuel consumption. Contrarily, the sharks remain largely free of bioadhesion despite spending their entire lives submerged. The sharks have placoid scales, which consist of rectangular base embedded in the skin with tiny spines that poke up from the surface. It is found that this special structure can make great deal of function for antifouling. In our report, parallel works for antifouling mechanisms were motivated by Triakidae shark feeding, observations on shark skin, and the experiments of benthic diatoms adhesion and Mytilus edulis byssus attachment. And, the optical configurations were acquired by using 3D video microscope and environment scanning electron microscope (ESEM). The results showed that, the benthic diatoms adhesion on the naked skin of living sharks was obviously fewer than the dead ones, and could not be found on the surface of placoid scales. As the time progressed, the rate of Mytilus edulis byssus attachment reduced gradually. It was thought that, the water turbulent boundary on the surface was changed greatly and innumerable minimal vortex was generated when the water flow on the shark skin. The strong exchange of momentum in a turbulent boundary layer would produce high-speed lumps approaching the surface, which could develop strong shear stress. Benthic diatoms and mussel could not attached firmly or be cleared easily when the shear stress became stronger than the adhesion power of these organisms. After finding the real working mechanism of antifouling for sharks, it could be used to direct the progresses of synthesizing biomimetic coatings or materials with antifouling performance in the future.
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Huang, Aiyou, Yujue Wang, Jiawen Duan, Shiyi Guo und Zhenyu Xie. „Differential Response of Phaeodactylum tricornutum and Cylindrotheca fusiformis to High Concentrations of Cu2+ and Zn2+“. Water 14, Nr. 20 (19.10.2022): 3305. http://dx.doi.org/10.3390/w14203305.
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Diatoms can be used as biosensors to assess aquatic environment quality, because they are widely distributed in almost all aquatic environments and show varied sensitivities toward heavy metal ions. The marine planktonic diatoms Phaeodactylum tricornutum (P. tricornutum) and Cylindrotheca fusiformis (C. fusiformis) are typical representatives of planktonic diatoms and benthic diatoms, respectively. C. fusiformis is very sensitive to changes in the concentration of heavy metal ions, and can be used as an indicator of the quality of the sedimental environment, while P. tricornutum can tolerate higher concentrations of heavy metal ions. To explore the potential difference in responses to heavy metal ions between planktonic and benthic diatoms, we compared the transcriptome of P. tricornutum and C. fusiformis under Cu2+ and Zn2+ treatment. The results indicated that P. tricornutum has several genes involved in ion transmembrane transport and ion homeostasis, which are significantly downregulated under Cu2+ and Zn2+ treatment. However, this enrichment of ion transmembrane transport- and ion homeostasis-related genes was not observed in C. fusiformis under Cu2+ and Zn2+ treatment. Additionally, genes related to heavy metal ion stress response such as peroxiredoxin, peroxidase, catalase, glutathione metabolism, phytochelatin, oxidative stress and disulfide reductase, were upregulated in P. tricornutum under Cu2+ and Zn2+ treatment, whereas most of them were downregulated in C. fusiformis under Cu2+ and Zn2+ treatment. This difference in gene expression may be responsible for the difference in sensitivity to heavy metals between P. tricornutum and C. fusiformis.
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Short, Susan K., John T. Andrews, Kerstin M. Williams, Nancy J. Weiner und Scott A. Elias. „Late Quaternary Marine and Terrestrial Environments, Northwestern Baffin Island, Northwest Territories“. Géographie physique et Quaternaire 48, Nr. 1 (23.11.2007): 85–95. http://dx.doi.org/10.7202/032974ar.
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ABSTRACT Paleoenvironmental data were analyzed from terrestrial, lake, and marine sediments collected near Arctic Bay, Baffin Island, N.W.T. Eighteen new radiocarbon dates provide chronological control, superseding earlier results. Spuriously old dates were obtained from both sandy peats and low-organic lake sediments. The most reliable dates were from marine shells and foraminifera. They indicate that déglaciation was underway by 9000 BP rather than 16,000 BP. Over the period of the record, the local environment was characterized by a high arctic pollen assemblage dominated by grass, sedge, and willow; a middle Holocene warm period is indicated by increased willow, herb, and moss values. Sea-ice conditions were severe enough to inhibit the growth of diatoms until ca. 6300 BP and ice proximal and deglacial conditions prevailed in the fiords until ca. 6000 BP. Diatom productivity increased between 3000 BP and 2500 BP, suggesting warmer surface waters and less sea ice. After 2000 BP diatom accumulation decreased sharply, due to a cooling of climate. The foraminifera indicate a major change in bottom water conditions ca. 4000 BP as the benthic species shift from a calcareous to an arenaceous assemblage.
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Prelle, Lara R., Ina Schmidt, Katherina Schimani, Jonas Zimmermann, Nelida Abarca, Oliver Skibbe, Desiree Juchem und Ulf Karsten. „Photosynthetic, Respirational, and Growth Responses of Six Benthic Diatoms from the Antarctic Peninsula as Functions of Salinity and Temperature Variations“. Genes 13, Nr. 7 (16.07.2022): 1264. http://dx.doi.org/10.3390/genes13071264.
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Temperature and salinity are some of the most influential abiotic parameters shaping biota in aquatic ecosystems. In recent decades, climate change has had a crucial impact on both factors—especially around the Antarctic Peninsula—with increasing air and water temperature leading to glacial melting and the accompanying freshwater increase in coastal areas. Antarctic soft and hard bottoms are typically inhabited by microphytobenthic communities, which are often dominated by benthic diatoms. Their physiology and primary production are assumed to be negatively affected by increased temperatures and lower salinity. In this study, six representative benthic diatom strains were isolated from different aquatic habitats at King George Island, Antarctic Peninsula, and comprehensively identified based on molecular markers and morphological traits. Photosynthesis, respiration, and growth response patterns were investigated as functions of varying light availability, temperature, and salinity. Photosynthesis–irradiance curve measurements pointed to low light requirements, as light-saturated photosynthesis was reached at <70 µmol photons m−2 s−1. The marine isolates exhibited the highest effective quantum yield between 25 and 45 SA (absolute salinity), but also tolerance to lower and higher salinities at 1 SA and 55 SA, respectively, and in a few cases even <100 SA. In contrast, the limnic isolates showed the highest effective quantum yield at salinities ranging from 1 SA to 20 SA. Almost all isolates exhibited high effective quantum yields between 1.5 °C and 25 °C, pointing to a broad temperature tolerance, which was supported by measurements of the short-term temperature-dependent photosynthesis. All studied Antarctic benthic diatoms showed activity patterns over a broader environmental range than they usually experience in situ. Therefore, it is likely that their high ecophysiological plasticity represents an important trait to cope with climate change in the Antarctic Peninsula.
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Lowery, Christopher M., Paul R. Bown, Andrew J. Fraass und Pincelli M. Hull. „Ecological Response of Plankton to Environmental Change: Thresholds for Extinction“. Annual Review of Earth and Planetary Sciences 48, Nr. 1 (30.05.2020): 403–29. http://dx.doi.org/10.1146/annurev-earth-081619-052818.
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Severe climatic and environmental changes are far more prevalent in Earth history than major extinction events, and the relationship between environmental change and extinction severity has important implications for the outcome of the ongoing anthropogenic extinction event. The response of mineralized marine plankton to environmental change offers an interesting contrast to the overall record of marine biota, which is dominated by benthic invertebrates. Here, we summarize changes in the species diversity of planktic foraminifera and calcareous nannoplankton over the Mesozoic–Cenozoic and that of radiolarians and diatoms over the Cenozoic. We find that, aside from the Triassic–Jurassic and Cretaceous–Paleogene mass extinction events, extinction in the plankton is decoupled from that in the benthos. Extinction in the plankton appears to be driven primarily by majorclimatic shifts affecting water column stratification, temperature, and, perhaps, chemistry. Changes that strongly affect the benthos, such as acidification and anoxia, have little effect on the plankton or are associated with radiation. ▪ Fossilizing marine plankton provide some of the most highly temporally and taxonomically resolved records of biodiversity since the Mesozoic. ▪ The record of extinction and origination in the plankton differs from the overall marine biodiversity record in revealing ways. ▪ Changes to water column stratification and global circulation are the main drivers of plankton diversity. ▪ Anoxia, acidification, and eutrophication (which strongly influence total marine fossil diversity) are less important in the plankton.
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Petrov, A. N., und E. L. Nevrova. „Estimation of cell distribution heterogeneity at toxicological experiments with clonal cultures of benthic diatoms“. Marine Biological Journal 5, Nr. 2 (30.06.2020): 76–87. http://dx.doi.org/10.21072/mbj.2020.05.2.07.
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An increase in anthropogenic pressure on coastal water areas requires regular monitoring of marine ecosystems. The appropriate bioindicators for indirect assessment of the quality of the near-shore environment are benthic diatom algae, which are a key element of coastal communities and are highly sensitive to environmental impact. Changes in the development of diatoms under the influence of various toxicants may be used as relevant tool for monitoring of marine environment quality. However, scientific and methodological approaches to application of benthic diatom algae as test objects remain unstudied. One of the important methodological problems is the assessment of the significance of the samples in experimental vessels when counting cells abundance at different stages of toxicological test. The study is focused on assessment of the statistical significance of the equality of the initial mean number of cells of clonal culture inoculum placed into each of the replicates, as well as the statistical uniformity of cell distribution over the entire bottom area of Petri dishes. We used clonal cultures of three benthic diatom species belonging to different classes of Bacillariophyta: Thalassiosira excentrica Cleve, 1903 (Coscinodiscophycea), Ardissonea crystallina (C. Agardh) Grunow, 1880 (Fragilariophyceae), and Pleurosigma aestuarii (Bréb. in Kütz.) W. Smith, 1853 (Bacillariophyceae). They significantly differ in valve morphology and life history (floating in water mass, attached to substrate, and motile). The results of statistical comparison of cell number variability in the experiment for all studied species confirmed the absence of significant differences between the mean values of the tested parameter at a standard significance level (0.05). It was shown that despite specific differences in cell growth rate during the experiment, the variability in cell number in the microscope viewing fields varies irregularly. The highest value of the variability coefficient was observed on the 5th day for the small-sized species T. excentrica (Cv = 42…55 %), and the lowest variability – for the large-cell species A. crystallina (Cv = 27…31 %). The absence of significant differences in cell number between three replicates (for each species) was established both during the initial placing of inoculum into the dishes and on the following days of the experiment. The conclusion is applicable for each of diatom species studied, which allows to consider all replicates as subsamples of the replicate sample and to average the results obtained at different stages of the toxicological experiment. The uniformity of cell distribution throughout experimental dishes bottom, which does not depend on species and absolute cell number, was statistically proven. The results obtained allow to statistically reliably estimate the changes in cell number at different stages of toxicological experiment according to replicate sampling, based on cell counting in a limited number of viewing fields.