Bibliographies thématiques / Marine benthic diatoms

Littérature scientifique sur le sujet « Marine benthic diatoms »

Auteur : Grafiati
Publié le 25 mai 2024

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Articles de revues sur le sujet "Marine benthic diatoms"

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Barron, John A., et 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., et 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.
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David, Louis. « Marine benthic diatoms in China ». Geobios 19, no 5 (janvier 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 (janvier 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 et Ana Judith Marmolejo-Rodríguez. « Response of Benthic Diatom Assemblages to Contamination by Metals in a Marine Environment ». Journal of Marine Science and Engineering 9, no 4 (19 avril 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., et I. A. Prushkovskaya. « Diatoms in Surface Sediments of the Academy Bay of the Sea of Okhotsk ». Биология моря 49, no 2 (1 mars 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 et Jason M. Hall-Spencer. « Diatoms Dominate and Alter Marine Food-Webs When CO2 Rises ». Diversity 11, no 12 (16 décembre 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 et 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, no 19 (10 octobre 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 et Nina Dzhembekova. « Diversity and habitat preferences of benthic diatoms from South Bay (Livingston Island, Antarctica) ». Plant Ecology and Evolution 155, no 1 (30 mars 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 (janvier 1987) : 325. http://dx.doi.org/10.1016/0031-0182(87)90089-7.

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Thèses sur le sujet "Marine benthic diatoms"

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PICHIERRI, SALVATORE. « Interactions between the toxic benthic dinoflagellate Ostreopsis cf ovata and marine diatoms ». Doctoral thesis, Università Politecnica delle Marche, 2017. http://hdl.handle.net/11566/245283.

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La produzione di metaboliti secondari è stata osservata in molti organismi fitoplanctonici, incluse le diatomee che sono in grado di rilasciare diversi tipi di aldeidi polinsaturi (PUAs). Diversi studi hanno descritto la capacità di questi composti di influenzare la riproduzione invertebrati e la crescita del fitoplancton. Tuttavia, questi studi si sono concentrati sul ruolo ecologico delle PUAs principalmente in ambiente pelagico e nessuna informazione è disponibile sul loro effetto in quello bentonico. Ostreopsis cf. ovata è un dinoflagellato tossico bentonico che causa massicce fioriture in diverse aree costiere del Mar Mediterraneo incluso il nord Adriatico. In questa tesi ho investigato le interazioni, mediate da composti allelopatici, tra alcune diatomee bentoniche e Ostreopsis. I risultati della tesi di dottorato hanno messo per la prima volta in evidenza la produzione di PUAs in tre diatomee bentoniche comuni del nord Adriatico, cioè Proschkinia complanatoides, Tabularia affinis, Navicula sp . Quasi la totalità delle PUAs prodotte da Navicula sp. era costituita da catene medio corte mentre i profili di T. affinis e P. complanatoides apparivano più diversificati. Il secondo esperimento, ha mostrato una marcata inibizione della crescita di O. cf. ovata quando coltivato in presenza di tre PUAs commerciali. Con le catene lunghe sono stati osservati effetti più deleteri rispetto alle catene corte e l'analisi morfologica ha rivelato la presenza di forme aberranti (perdita mobilità, contrazione del citoplasma e formazione di vescicole anomale), danno al DNA, diminuzione delle rese quantiche del fotosistema II e aumento del contenuto di lipidi. Il mio ultimo studio ha sottolineato l'inibizione della crescita di O. cf. ovata quando quando veniva esposto ai filtrati di cinque diatome produttrici di PUA, due planctoniche (Skeletonema marinoi, Thalassiosira sp.) e tre bentoniche (P. complanatoides, Navicula sp. e T.affinis), Oltre a questi effetti, è stato osservato la presenza di forme anomale e danno al DNA.
The production of secondary metabolites was reported in many phytoplanktonic organisms including diatoms that have been shown to release different types of polyunsaturated aldehydes (PUAs). Several studies described the ability of these compounds to affect the invertebrate reproduction and the phytoplankton growth. However, these studies have focused the ecological role of PUAs primarily in pelagic environment and no information is available on their effect in the benthic one. Ostreopsis cf. ovata is a benthic toxic dinoflagellate causing massive blooms in different coastal areas of the Mediterranean Sea including the northern Adriatic Sea. In this thesis we investigated the interactions between some benthic diatoms and Ostreopsis mediated by allelopathic compound. The results of PhD thesis highlighted for the first time the production of PUAs compounds in three common benthic diatoms of the northern Adriatic Sea, i.e. Proschkinia complanatoides, Tabularia affinis, Navicula sp.. Almost the totality of PUAs produced by Navicula sp. consisted of low or medium-chained while the PUAs profiles of T. affinis and P. complanatoides appear more diversified. In a second experiment, we demonstrated a marked inhibition of of O. cf. ovata growth when it was grown in the presence of three commercial PUAs. A higher deleterious effects was observed with longer-chain molecules than with shorter-chain ones and the morphological analysis revealed presence of aberrant forms (motionless, contraction of cytoplasm and formation of abnormal vesicle-like structures), DNA damage, decrease of maximum and effective quantum yields of photosystem II and increase of lipid content. My last study pointed out the inhibition of O. cf. ovata growth when it was exposed to the filtrates of five diatom-PUA producers, two planktonic (Skeletonema marinoi, Thalassiosira sp.) and three benthic (P. complanatoides, Navicula sp. and T.affinis), In addition to these effects, the presence of abnormal forms and a DNA damage were observed.
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McGee, Dorien Kymberly. « Morphologic comparisons of shallow and deepwater benthic marine diatoms of Onslow Bay, North Carolina / ». Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/mcgeed/dorienmcgee.pdf.

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Busse, Svenja. « Benthic diatoms in the Gulf of Bothnia : Community analysis and diversity ». Doctoral thesis, Uppsala University, Plant Ecology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2591.

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Benthic diatoms are valuable tools for biological monitoring and paleo-ecological reconstruction of past environmental conditions. This thesis aims at describing size-related properties of benthic diatoms and suggests that data assessment for community analysis can be improved by considering the importance of scale. It investigates which environmental factors structure epilithic diatom communities on the coast of the Gulf of Bothnia and identifies environmental factors correlated with phytobenthic biomass. It also contributes to the floristic knowledge of the Baltic Sea.

Diatom species show large variation in size. The responses of large species (≥1000 μm3) in diatom communities to environmental factors are underestimated if solely measured as relative abundance, as is the common practice. However, relative abundance gives the best gradient resolution, as compared to surface area and biovolume, if species are counted separately in two biovolume classes. Small and large species in the same community may respond differently to the same environmental factors.

To assess the principal environmental factors structuring diatom communities in the Gulf of Bothnia, 270 quantitative samples were collected from submerged stones. Sampling was carried out in spring in four areas of the Bothnian Bay, characterized by a stable north-south salinity gradient (0.4-3.3 psu), and in three areas of the Bothnian Sea which has a rather uniform salinity of ca. 5 psu. Canonical correspondence analysis (CCA) identified salinity and exposure to wave action as the principal factors structuring the diatom communities of the Bothnian Bay, whereas exposure to wave action was the principal factor in the Bothnian Sea. Measurements of relative ignition loss suggested that the cover of macroalgae, and thereby the higher abundance of epiphytic diatoms in the epilithic samples, was positively correlated with salinity in the Bothnian Bay and with water movement in the Bothnian Sea.

Two new brackish water species are described, Navicula sjoersii S. Busse & Snoeijs and N. bossvikensis S. Busse & Snoeijs. The new species are compared with N. perminuta Grunow, a common brackish-water species.

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Darrow, Brian P. « Effects of Nutrients From the Water Column on the Growth of Benthic Microalgae in Permeable Sediments ». Scholar Commons, 2007. https://scholarcommons.usf.edu/etd/200.

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In some continental shelf sediments integrated benthic microalgal biomass is greater than the integrated phytoplankton biomass in the overlying water column. In addition, benthic microalgae may account for up to 10% of the primary production responsible for the coastal fishery yield of the eastern United States. A three-dimensional model of the eastern Gulf of Mexico examines the effects of water-column nutrient sources on the growth of benthic microalgae. To parameterize the exchange of nutrients across the sediment/water interface in these permeable sediments, a non-local exchange submodel was constructed and tested within the framework of the model's grid. Based on the results of the three dimensional simulations, the growth of benthic microalgae from water-column nutrients is highly dependent on the light limitation of overlying phytoplankton. When light is available to phytoplankton in high enough quantities, water-column nutrients are used up before reaching the sediments. When the overlying phytoplankton are light limited, nutrients are able to reach the sediments where the shade adapted benthic microalgae can grow.
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Ubertini, Martin. « Déterminisme de la remise en suspension des diatomées benthiques au travers du couplage benthos-pelagos ». Caen, 2012. http://www.theses.fr/2012CAEN2056.

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La remise en suspension du microphytobenthos est un processus clé du couplage benthos-pelagos dans de nombreux écosystèmes marins côtiers. Si les facteurs physiques comme l’hydrodynamisme ou le vent participent largement à cette remise en suspension, la macrofaune benthique joue également un rôle primordial par les processus de bioturbation. De plus, les diatomées benthiques, constituant la communauté la plus importante du microphytobenthos, sont capables de modifier leur propre remise en suspension par l’excrétion de substances exopolymériques limitant l’érosion du sédiment. La complexité de la remise en suspension réside donc dans la multiplicité des variables physiques, chimiques et biologiques associées. L’objectif de cette étude était donc de mieux comprendre la remise en suspension des diatomées benthiques à l’échelle de l’écosystème, par l’étude du couplage benthos-pelagos au niveau de deux écosystèmes côtiers contrastés comme à l’échelle des processus impliqués par l’étude de la remise en suspension en érodimètre. La remise en suspension joue un rôle primordial dans les écosystèmes estuariens et modifie l’équilibre des systèmes de façon saisonnière. Les caractéristiques sédimentaires des écosystèmes conditionnent la remise en suspension par l’interaction de l’état physiologique du biofilm et de la structure des mélanges sablo-vaseux. La présence de faune rajoute un degré d’interaction, à l’exemple de la coque Cerastoderma edule qui se révèle être un acteur majeur du couplage benthos-pelagos
La remise en suspension du microphytobenthos est un processus clé du couplage benthos-pelagos dans de nombreux écosystèmes marins côtiers. Si les facteurs physiques comme l’hydrodynamisme ou le vent participent largement à cette remise en suspension, la macrofaune benthique joue également un rôle primordial par les processus de bioturbation. De plus, les diatomées benthiques, constituant la communauté la plus importante du microphytobenthos, sont capables de modifier leur propre remise en suspension par l’excrétion de substances exopolymériques limitant l’érosion du sédiment. La complexité de la remise en suspension réside donc dans la multiplicité des variables physiques, chimiques et biologiques associées. L’objectif de cette étude était donc de mieux comprendre la remise en suspension des diatomées benthiques à l’échelle de l’écosystème, par l’étude du couplage benthos-pelagos au niveau de deux écosystèmes côtiers contrastés comme à l’échelle des processus impliqués par l’étude de la remise en suspension en érodimètre. La remise en suspension joue un rôle primordial dans les écosystèmes estuariens et modifie l’équilibre des systèmes de façon saisonnière. Les caractéristiques sédimentaires des écosystèmes conditionnent la remise en suspension par l’interaction de l’état physiologique du biofilm et de la structure des mélanges sablo-vaseux. La présence de faune rajoute un degré d’interaction, à l’exemple de la coque Cerastoderma edule qui se révèle être un acteur majeur du couplage benthos-pelagos
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Cunningham, LK. « Benthic diatom communities of coastal marine environments in the Windmill Islands, Antarctica ». Thesis, 2003. https://eprints.utas.edu.au/17310/1/whole-cunningham-thesis-2013.pdf.

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This project examined the effects of ecological factors and anthropogenic contaminants on benthic diatom communities near Casey Station, in the Windmill Islands, Antarctica. Preliminary sampling indicated significant compositional differences occurred between diatom communities in bays immediately adjacent to Casey Station and those more distant. Subsequently, a more detailed appraisal of spatial variability in benthic diatom communities was undertaken. Significant differences in community composition were demonstrated for all scales examined, however, increased distances between samples typically corresponded to increased dissimilarity. The influence of environmental factors on spatial variability was assessed using direct gradient ordination techniques. Grainsize, particularly the mud content, accounted for the majority of variation in diatom abundances explained by the measured environmental variables. Differences in light availability, water depth and grain-size explained 60% of the variation in community composition observed between locations. The remaining 40% of the variation in diatom community composition remains unexplained; potential causes include freshwater input, and chemical contamination. A preliminary analysis of temporal variability in benthic diatom communities from the Windmill Islands is presented. Seasonal, short-term (l00's of years) and long term (1000's of years) changes in community composition were examined at several locations. Temporal variability of the diatom communities within Brown Bay was also assessed, in conjunction with metal and Pb210 data. Within one core, a shift in community composition was detected subsequent to the onset of chemical contamination. Some changes in species abundance exceeded the natural variability observed in control cores, and thus were attributable to chemical contamination. Relationships between diatom abundances and concentrations of different metals within Brown Bay were examined using direct gradient analyses. Approximately 50% of the variation in the diatom community composition was related to metal concentrations. Further clarification of the interactions between metals, sediment grain-size and diatom community composition would be required prior to the development of predictive models. Direct gradient analyses also demonstrated a weak correlation between diatom community composition and hydrocarbon distribution. Manipulative field experiments were used to demonstrate that the composition of diatom communities can be influenc.ed by both metal and hydrocarbon contaminants at concentrations comparable to levels produced by station activities. This supports the conclusion that anthropogenic contaminants are responsible for some compositional differences observed in diatom communities, both within Brown Bay and between Brown Bay and reference locations.
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Bindhu, K. B. « Studies on diatoms along the South west coast of India in Relation to the hydrological Parameters ». Thesis, 2006. http://eprints.cmfri.org.in/7565/1/TH-144.pdf.

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The distribution and abundance of diatoms along the South west coast of India in relation to the hydrological parameters was studied by selecting three stations namely, Thalassery, Cochin and V izhinj am. The present study has been carried out with a view to study the diatoms of selected areas along the south west coast of India in relation to the hydrographic factors. Qualitative and quantitative studies were made along the nearshore and inshore areas following the standard procedures. Regression analysis was also conducted to study the various factors contributing the growth of diatoms along the near shore and inshore areas of the three selected stations. It was found that the hydrological parameters showed fluctuation from season to season and within season. Diatoms along the nearshore areas showed abundance and dominance during the monsoon season followed by the post monsoon season, while that along the inshore areas are having the highest dominance and abundance during post monsoon followed by monsoon season. The regression analysis indicates that the diatom population was contributed by different factors at different stations indicating that they are all independent. 133
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Livres sur le sujet "Marine benthic diatoms"

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Te-hsiang, Chin, dir. The marine benthic diatoms in China. Beijing : China Ocean Press, 1985.

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Chapitres de livres sur le sujet "Marine benthic diatoms"

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Araújo, Cristiano V. M., et Ignacio Moreno-Garrido. « Toxicity Bioassays on Benthic Diatoms ». Dans Handbook of Marine Microalgae, 539–46. Elsevier, 2015. http://dx.doi.org/10.1016/b978-0-12-800776-1.00036-4.

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Levinton, Jeffrey S. « Benthic Microorganisms, Seaweeds, and Sea Grasses ». Dans Marine Biology. Oxford University Press, 2021. http://dx.doi.org/10.1093/hesc/9780197543504.003.0018.

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This chapter discusses the diversity of microorganisms, algae, and plants that live on the seabed. It primarily focuses on benthic microorganisms, seaweeds, and sea grasses. All living organisms can be divided among basic domains based on DNA sequence relationships. Thus, according to Carl Worse and his colleague's data from DNA sequencing of ribosomal DNA genes: the three major divisions of life were Archaea, Bacteria, and Eukarya. The chapter also considers the function and characteristics of bacteria, which are known to be crucial in the process of decomposition. It discusses the features of cyanobacteria, diatoms, fungi, seaweeds, chlorophyta, and sea grasses.
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Gray, John S., et Michael Elliott. « Temporal variations in benthic assemblages ». Dans Ecology of Marine Sediments. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198569015.003.0011.

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Most (but by no means all) benthic species have larval stages which use the water column for dispersal. As indicated in the previous chapter, a key process affecting recruitment to sediment systems is the need to disperse larvae in order to colonize new areas, even to the extent of releasing larvae at spring tides when the tidal excursion will be greatest, thus effecting an even greater dispersal. Seasonal release of larvae is the norm: most species develop gametes in spring and spawn in late spring or early summer (see Rasmussen 1973 for an excellent data set of the times of planktonic larval occurrence and settlement by many important north-west European boreal benthic species). Some species, however, avoid the high competition for food at this time and release gametes in autumn and winter. Thus larvae of benthic organisms are a key and often dominating component of the spring–summer plankton and play important roles as food for planktonic species such as fish larvae. Conversely, a number of planktonic species have resting stages in sediments. The most important of these are undoubtedly the diatoms and many flagellates, and also certain calanoid copepods such as Acartia, which are of course key components of the phytoplankton and zooplankton respectively. Diatom cysts are often found, and there is increased interest in the survival and hatching processes of dinoflagellate cysts that lead to harmful algal blooms. Similarly, the seasonal occurrence of many zooplankton species results from hatching of resting stages in the sediment (see Smetacek (1995), Boero et al. (1996), Pati et al. (1999) and Boero and Bonsdorff (2008) for reviews). The implication of many important planktonic species having benthic resting phases is that by predating cysts, benthic species may be able to control abundances of planktonic species. In this context the meiofauna are important predators (Pati et al. 1999). It is now important to consider the scales of temporal variation in benthic assemblages. First, seasonal changes occur in benthic assemblages of soft sediments even in the depths of the deep sea (e.g. Hsü and Thiede 1992). In spring, as light levels and temperature increase, a plankton bloom occurs.
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Emília Cunha, Maria, Hugo Quental Ferreira, Ana Barradas et Pedro Pousão-Ferreira. « Response of Marine Plankton Communities in Ponds to the Presence of Vertical Structures ». Dans Plankton Communities [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97475.

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The effects of bottom vertical structures like AquaMats® in enhancing plankton productivity was evaluated. One experimental earthen pond of 500 m2 was provided with AquaMats® increasing the surface substrate area 12 times and water quality, phytoplankton and zooplankton populations developed during almost 100 days was compared with a pond without AquaMats®. Their presence favored the development of Dinoflagellates (Miozoa, Dinophyceae), mostly Gymnodiniales, which may be of some concern since some species of this group have been associated with toxic algal blooms while in the ponds without AquaMats® Diatoms (Bacillariophyta) predominate. In both ponds plankton production was very much sculptured by external nutrients added to the systems. The balance between different nutrients is extremely important to regulate the phytoplankton populations with Diatoms blooming at silicate concentrations higher than 2 μM and below this level and at low nitrate and high ammonium being more appropriate for Dinoflagellates. The linkage between phytoplankton and zooplankton population in ponds is strong with zooplankton exerting control over the phytoplankton population and vice-versa. The use of vertical substrates enhances plankton productivity by increasing the substrate area for periphyton fixation. The main zooplankton taxonomic groups associated with the presence of AquaMats® were Calanoid and Harpacticoid copepodites and nauplii, veligers of gastropods and trochophore of polychaets, larval stages of organisms that except for calanoid copepods are benthic and correspond to the meroplanktonic phase in the life cycle of those organisms.
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Reise, Karsten. « Grazing on sediment shores ». Dans Plant-Animal Interactions in the Marine Benthos, 133–46. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198577546.003.0006.

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Abstract In intertidal mud and sand, diatoms are the dominant microalgae, with about 10 cells cm-2 andanannual net production of roughly 100 g C m-2. One-third may be consumed by the zoobenthos. Large deposit feeders ingest microalgae together with sediment particles. Smaller ones scrape algal cells from sand grains or capture mobile diatoms. These are either ingested intact or are punctured and sucked out. Bulk measurements on primary production and on consumption provide little insight into plant-animal interactions in shallow sediments. Analyses should differentiate between type of algae and mode of feeding. Large epipelic diatoms are occasionally subject to overgrazing, while the small epipsammic diatoms are utilized to a lesser extent. At moderate density some grazers stimulate algal growth. Gardening is achieved by excretion of ammonia and secretion of mucus. The extracellular mucopolysaccharides produced by diatoms increase the surface stability of sediments and enhance the accretion of organic deposits. This is beneficial to deposit feeders. Heavy grazing on mud-flats reduces diatom density, and the habitat may become more sandy because of interference with the accretion of mud. In sand, bioturbating macrofauna depresses microalgal growth by frequent burial. Large burrowers occasionally anchor strings of green macroalgae, which subsequently grow into coherent algal mats, changing the entire habitat profoundly.
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Riebesell, Ulf, et Philippe D. Tortell. « Effects of Ocean Acidification on Pelagic Organisms and Ecosystems ». Dans Ocean Acidification. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199591091.003.0011.

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Over the past decade there has been rapidly growing interest in the potential effects of ocean acidification and perturbations of the carbonate system on marine organisms. While early studies focused on a handful of phytoplankton and calcifying invertebrates, an increasing number of investigators have begun to examine the sensitivity to ocean acidification of various planktonic and benthic organisms across the marine food web. Several excellent review articles have recently summarized the rapidly expanding literature on this topic (Fabry et al. 2008; Doney et al. 2009 ; Joint et al. 2011). The focus of this chapter is on the potential ecosystem-level effects of ocean acidification. Starting with a brief review of the basic physical, chemical, and biological processes which structure pelagic marine ecosystems, the chapter explores how organismal responses to perturbations of the carbonate system could scale up in both time and space to affect ecosystem functions and biogeochemical processes. As with many chapters in this volume, and indeed much of the ocean acidification literature at present, our review raises more questions than it answers. It is hoped that these questions will prove useful for articulating and addressing key areas of future research. Complexity in marine pelagic food webs results from the interactions of multiple trophic levels across a range of temporal and spatial scales. The traditional view of marine food webs (Steele 1974) involved a relatively short trophic system in which large phytoplankton (e.g. net plankton such as diatoms) were grazed by a variety of mesozooplankton (e.g. copepods), which were in turn consumed by second-level predators, including many economically important fish and invertebrate species. This ‘classic’ marine food web is typical of high-productivity regions such as coastal upwelling regimes (Lassiter et al. 2006). A characteristic feature of these systems is a strong decoupling between primary production and grazing, which results from the different metabolic rates of consumers and producers and, in many cases, ontogenetic and seasonal delays in the emergence of feeding predators. The uncoupling between phytoplankton and their consumers leads to significant export of organic material out of the euphotic zone, the so-called biological carbon pump (discussed further below).
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Asioli, Alessandra, Anna Maria Borsetti, Lucilla Capotondi et Paolo Colantoni. « Past diatom blooms and benthonic foraminifera extinction detected in old Adriatic sediments ». Dans Marine Coastal Eutrophication, 133–36. Elsevier, 1992. http://dx.doi.org/10.1016/b978-0-444-89990-3.50017-1.

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Actes de conférences sur le sujet "Marine benthic diatoms"

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Park, J. « Taxonomic notes on two marine benthic diatoms in Korean tidal flats : Climaconeis sp. and Petrodictyon voigtii (Skvortsov) J. Park & ; C.H. Koh, comb. nov. » Dans 1st Central European Diatom Meeting. Botanic Garden and Botanical Museum Berlin-Dahlem, 2007. http://dx.doi.org/10.3372/cediatom.126.

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Nagarajan, N., et M. Senthil Kumar. « Seasonal changes in the marine benthic diatom populations of southeast coast in the Kattumavadi region of Tamilnadu, India ». Dans THIRD VIRTUAL INTERNATIONAL CONFERENCE ON MATERIALS, MANUFACTURING AND NANOTECHNOLOGY. AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0096485.

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