The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Richard Wetherbee - One of the best experts on this subject based on the ideXlab platform.
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The biology of biofouling Diatoms and their role in the development of microbial slimes.
Biofouling, 2008Co-Authors: Paul Molino, Richard WetherbeeAbstract:Diatoms are a major component of microbial slimes that develop on man-made surfaces placed in the marine environment. Toxic antifouling paints, as well as environmentally friendly, fouling-release coatings, tend to be effective against most fouling organisms, yet fail badly to Diatom slimes. Biofouling Diatoms have been found to tenaciously adhere to and colonise even the most resistant of artificial surfaces. This review covers the basic biology of fouling marine Diatoms, their mechanisms of adhesion and the nature of their adhesives, as well as documenting the various approaches that have been utilised to understand the formation and maintenance of Diatom biofouling layers.
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The glucans extracted with warm water from Diatoms are mainly derived from intracellular chrysolaminaran and not extracellular polysaccharides
European Journal of Phycology, 2004Co-Authors: Anthony Chiovitti, Paul Molino, Rongwei Teng, Timothy Spurck, Simon A. Crawford, Richard WetherbeeAbstract:Several recent studies have employed warm-water treatment of Diatom cells to extract nominally bound extracellular polymeric substances. Where examined, the dominant neutral sugar in these extracts was glucose. In the present study, we sought to characterize the structure of the glucose-rich polymers in the water extracts of Diatoms and to determine the origin of these polymers. The marine Diatoms surveyed were Phaeodactylum tricornutum, Cylindrotheca fusiformis, Craspedostauros australis and Thalassiosira pseudonana. A freshwater species, Pinnularia viridis, was also investigated for the dye labelling experiments. Freshly harvested marine Diatoms were extracted with water at 30°C for 1?h. Constituent monosaccharide analyses showed that glucose was the dominant neutral sugar (80???95 mol% of the total) in the extracts from three marine species, whereas the P. tricornutum extract contained predominantly ribose, galactose and glucose, and was inferred to be enriched in low-molecular-weight components. Linkage analysis of the constituent monosaccharides and proton nuclear magnetic resonance spectroscopy showed that the glucose in these extracts was derived primarily from 1,3-?-D-glucan. Immunocytochemistry with a monoclonal anti-1,3-?-D-glucan antibody confirmed that the glucan was localized in the vacuoles of Diatom cells preserved by freeze-substitution. Nearly all Diatom cells incubated with a fluorescent dye, DiBAC4(3), during warm water treatment at 30°C or 60°C incorporated the dye, demonstrating that the membrane integrity of the Diatoms was compromised and supporting the contention that intracellular glucan was released during the treatment. In light of these data, the extracellular glucans of Diatoms reported in some previous studies are re-interpreted as intracellular chrysolaminaran. Several recent studies have employed warm-water treatment of Diatom cells to extract nominally bound extracellular polymeric substances. Where examined, the dominant neutral sugar in these extracts was glucose. In the present study, we sought to characterize the structure of the glucose-rich polymers in the water extracts of Diatoms and to determine the origin of these polymers. The marine Diatoms surveyed were Phaeodactylum tricornutum, Cylindrotheca fusiformis, Craspedostauros australis and Thalassiosira pseudonana. A freshwater species, Pinnularia viridis, was also investigated for the dye labelling experiments. Freshly harvested marine Diatoms were extracted with water at 30°C for 1?h. Constituent monosaccharide analyses showed that glucose was the dominant neutral sugar (80???95 mol% of the total) in the extracts from three marine species, whereas the P. tricornutum extract contained predominantly ribose, galactose and glucose, and was inferred to be enriched in low-molecular-weight components. Linkage analysis of the constituent monosaccharides and proton nuclear magnetic resonance spectroscopy showed that the glucose in these extracts was derived primarily from 1,3-?-D-glucan. Immunocytochemistry with a monoclonal anti-1,3-?-D-glucan antibody confirmed that the glucan was localized in the vacuoles of Diatom cells preserved by freeze-substitution. Nearly all Diatom cells incubated with a fluorescent dye, DiBAC4(3), during warm water treatment at 30°C or 60°C incorporated the dye, demonstrating that the membrane integrity of the Diatoms was compromised and supporting the contention that intracellular glucan was released during the treatment. In light of these data, the extracellular glucans of Diatoms reported in some previous studies are re-interpreted as intracellular chrysolaminaran.
Judit Padisak - One of the best experts on this subject based on the ideXlab platform.
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expanding the trait based concept of benthic Diatoms development of trait and species based indices for conductivity as the master variable of ecological status in continental saline lakes
Ecological Indicators, 2018Co-Authors: Csilla Stengerkovacs, Kitti Kormendi, Edina Lengyel, Andras Abonyi, Eva Hajnal, Beata Szabo, Krisztina Buczko, Judit PadisakAbstract:Abstract Shallow, saline inland lakes occur over large areas in Central-Europe and they bear exceptionally high biological conservation values. Climate change and anthropogenic activities threaten their natural conditions, or even their existence. These aquatic ecosystems are exposed to multiple stress like naturally high conductivity, pH and nutrient load with very low transparency for light. As they are subjects of criteria set by the EC Water Framework Directive and biological conservation managment, there is an urgent need for developing a suitable quality index for their ecological status assessment. As one major Biological Quality Element, benthic Diatoms may provide a reliable basis for their ecological status indication. Here, in a large data set covering the soda lakes of the Carpathian basin, we developed a species- and a trait-based Diatom ecological status index. First, based on the weighted average method, we developed a type specific, species-based Diatom index (DISP = Diatom Index for Soda Pans) using conductivity as master variable of environmental constrains; and therefore the ecological status in soda lakes. Furthermore, by adapting and improving further the widely-used Diatom ecological guild concept, we also developed an alternative trait-based index, which helps avoiding some limitations arising from the obvious complexity of the taxonomy-based approach. Our DISP index covered a significantly larger species pool for index calculation, and responded to conductivity in a more reliable way compared to other available indices. In the trait-based index (TBI) motility, small cell size, and less roundish, more elongated shape as functional and morphological traits indicated pristine ecological conditions (i.e high conductivity) of the soda pans. Planktic life form, high and low ecological guild profiles, as well as the large cell size indicated worse ecological conditions (e.g. lower conductivity). Our study highlights that benthic Diatoms provide a reliable basis for ecological status assessment in soda lakes. While both the taxonomic and the functional trait approaches performed well in our analysis, the success of the trait-based approach may enable the use of our TBI index in biomonitoring and conservation management of soda lakes outside of the Carpathian basin, independently of the geographic location.
John P. Smol - One of the best experts on this subject based on the ideXlab platform.
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Lake Diatom responses to warming: reviewing the evidence
Journal of Paleolimnology, 2015Co-Authors: Kathleen M. Rühland, Andrew M. Paterson, John P. SmolAbstract:Algae, the dominant primary producers in many aquatic ecosystems, are critical to global biogeochemical cycling, and changes in their abundance and composition can cascade throughout aquatic food webs. Diatoms often dominate the algal communities in many freshwater systems. Their population dynamics are affected by a variety of environmental variables, many of which are linked to changes in water column properties and habitat availability, which themselves can be linked to shifts in ice cover, length of the growing season, thermal stability and stratification, vertical mixing patterns, habitat alterations, and the availability of resources such as light and nutrients. Climate has strong moderating controls on all of these fundamental aquatic processes, which can directly and indirectly alter species composition, abundance and seasonal dynamics of both periphytic and planktonic Diatoms. In this review, we examine the role that climate-mediated alterations in inter-related lake processes have played on Diatom community composition, dynamics and size structure, with particular attention to the recent success of planktonic Diatom species relative to heavier tychoplanktonic and small benthic Diatoms. We focus primarily on paleolimnological records, but also reference a wide spectrum of limnological and physiological studies to review and discuss how climate-driven shifts in lake properties may affect Diatom assemblage reorganization. Understanding the limnological and historical context of these often complex Diatom changes is key to making scientifically defensible interpretations of paleolimnological records. We further evaluate the plausibility of alternative explanations (e.g. atmospheric nitrogen deposition) for the recent success of small cyclotelloid species by examining trends in these planktonic Diatoms from a large number of sites. Using a weight-of-evidence approach, we conclude that recent climate change is the main driver that has led to ecological tipping points resulting in the recent success of small planktonic Diatoms that have been reported in many aquatic systems.
Geoffrey S Schladow - One of the best experts on this subject based on the ideXlab platform.
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lake warming favours small sized planktonic Diatom species
Proceedings of The Royal Society B: Biological Sciences, 2009Co-Authors: Monika Winder, John E Reuter, Geoffrey S SchladowAbstract:Diatoms contribute to a substantial portion of primary production in the oceans and many lakes. Owing to their relatively heavy cell walls and high nutrient requirements, planktonic Diatoms are expected to decrease with climate warming because of reduced nutrient redistribution and increasing sinking velocities. Using a historical dataset, this study shows that Diatoms were able to maintain their biovolume with increasing stratification in Lake Tahoe over the last decades; however, the Diatom community structure changed. Increased stratification and reduced nitrogen to phosphorus ratios selected for small-celled Diatoms, particularly within the Cyclotella genus. An empirical model showed that a shift in phytoplankton species composition and cell size was consistent within different depth strata, indicating that altered nutrient concentrations were not responsible for the change. The increase in small-celled species was sufficient to decrease the average Diatom size and thus sinking velocity, which strongly influences energy transfer through the food web and carbon cycling. Our results show that within the diverse group of Diatoms, small-sized species with a high surface area to volume ratio were able to adapt to a decrease in mixing intensity, supporting the hypotheses that abiotic drivers affect the size structure of planktonic communities and that warmer climate favours small-sized Diatom cells.
Jeffrey W Krause - One of the best experts on this subject based on the ideXlab platform.
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Silicon limitation facilitates virus infection and mortality of marine Diatoms
Nature Microbiology, 2019Co-Authors: Chana F. Kranzler, Jeffrey W Krause, Mark A. Brzezinski, Bethanie R. Edwards, William P. Biggs, Michael Maniscalco, John P. Mccrow, Benjamin A. S. Van Mooy, Kay D. Bidle, Andrew E. AllenAbstract:Diatoms are among the most globally distributed and ecologically successful organisms in the modern ocean, contributing upwards of 40% of total marine primary productivity^ 1 , 2 . By converting dissolved silicon into biogenic silica, and photosynthetically fixing carbon dioxide into particulate organic carbon, Diatoms effectively couple the silicon (Si) and carbon cycles and ballast substantial vertical flux of carbon out of the euphotic zone into the mesopelagic and deep ocean^ 3 – 5 . Viruses are key players in ocean biogeochemical cycles^ 6 , 7 , yet little is known about how viral infection specifically impacts Diatom populations. Here, we show that Si limitation facilitates virus infection and mortality in Diatoms in the highly productive coastal waters of the California Current Ecosystem. Using metatranscriptomic analysis of cell-associated Diatom viruses and targeted quantification of extracellular viruses, we found a link between Si stress and the early, active and lytic stages of viral infection. This relationship was also observed in cultures of the bloom-forming Diatom Chaetoceros tenuissimus , where Si stress accelerated virus-induced mortality. Together, these findings contextualize viruses within the ecophysiological framework of Si availability and Diatom-mediated biogeochemical cycling. Using metatranscriptomics of Diatom-associated viruses and quantification of extracellular viruses in coastal water samples, the authors link silicon limitation to increased virus-induced mortality of Diatoms, which could have implications for marine biogeochemical cycling.
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biogenic silica production and Diatom dynamics in the svalbard region during spring
Biogeosciences, 2018Co-Authors: Jeffrey W Krause, Israel A Marquez, Mar Fernandezmendez, Ingrid Wiedmann, Paul Wassmann, Philipp Assmy, Carlos M. Duarte, Svein Kristiansen, Susana AgustiAbstract:Abstract. Diatoms are generally the dominant contributors to the Arctic Ocean spring bloom, which is a key event in regional food webs in terms of capacity for secondary production and organic matter export. Dissolved silicic acid is an obligate nutrient for Diatoms and has been declining in the European Arctic since the early 1990s. The lack of regional silicon cycling information precludes understanding the consequences of such changes for Diatom productivity during the Arctic spring bloom. This study communicates the results from a cruise in the European Arctic around Svalbard, which reports the first concurrent data on biogenic silica production and export, export of Diatom cells, the degree of kinetic limitation by ambient silicic acid, and Diatom contribution to primary production. Regional biogenic silica production rates were significantly lower than those achievable in the Southern Ocean and silicic acid concentration limited the biogenic silica production rate in 95 % of samples. Compared to Diatoms in the Atlantic subtropical gyre, regional Diatoms are less adapted for silicic acid uptake at low concentration, and at some stations during the present study, silicon kinetic limitation may have been intense enough to limit Diatom growth. Thus, silicic acid can play a critical role in Diatom spring bloom dynamics. The Diatom contribution to primary production was variable, ranging from % to ∼100 % depending on the bloom stage and phytoplankton composition. While there was agreement with previous studies regarding the export rate of Diatom cells, we observed significantly elevated biogenic silica export. Such a discrepancy can be resolved if a higher fraction of the Diatom material exported during our study was modified by zooplankton grazers. This study provides the most direct evidence to date suggesting the important coupling of the silicon and carbon cycles during the spring bloom in the European Arctic.
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Biogenic silica production and Diatom dynamics in the Svalbard region during spring
2018Co-Authors: Jeffrey W Krause, Israel A Marquez, Ingrid Wiedmann, Paul Wassmann, Mar Fernández-méndez, Philipp Assmy, Carlos M. Duarte, Svein Kristiansen, Susana AgustiAbstract:<p><strong>Abstract.</strong> Diatoms are generally the dominant contributors to the Arctic Ocean spring bloom, which is a key event in regional food webs in terms of capacity for secondary production and organic matter export. Dissolved silicic acid is an obligate nutrient for Diatoms and has been declining in the European Arctic. The lack of regional silicon cycling information precludes understanding the consequences of such changes for Diatom productivity during the Arctic spring bloom. This study communicates the results from a cruise in the European Arctic around Svalbard reporting the first concurrent data on biogenic silica production and export, Diatom cellular export, the degree of kinetic limitation by ambient silicic acid, and Diatom contribution to primary production. Regional biogenic silica production rates were significantly lower than those achievable in the Southern Ocean and silicic acid concentration limited the biogenic silica production rate in 95&#8201;% of samples. Compared to Diatoms in the Atlantic subtropical gyre, regional Diatoms are less adapted for silicic acid uptake at low substrate, and at some stations during the present study, silicon limitation may have been intense enough to limit Diatom growth. Thus, silicic acid can play a critical role in Diatom spring bloom dynamics. Diatom contribution to primary production was variable, ranging from <&#8201;10&#8201;% to ~&#8201;100&#8201;% depending on the bloom stage and phytoplankton composition. While there was agreement with previous studies regarding the rate of Diatom cellular export, we observed significantly elevated biogenic silica export. Such a discrepancy can be resolved if a higher fraction of the Diatom material exported during our study was modified by zooplankton grazers or originated from melting ice. This study provides the most-direct evidence to date suggesting the important coupling of the silicon and carbon cycles during the spring bloom in the European Arctic.</p>
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net biogenic silica production and the contribution of Diatoms to new production and organic matter export in the costa rica dome ecosystem
Journal of Plankton Research, 2016Co-Authors: Jeffrey W Krause, Michael R Stukel, Andrew G Taylor, Darcy A A Taniguchi, Alain De Verneil, Michael R LandryAbstract:We determined the net rate of biogenic silica (bSiO2) production and estimated the Diatom contribution to new production and organic matter export in the Costa Rica Dome during summer 2010. The shallow thermocline significantly reduces bSiO2 dissolution rates below the mixed layer, leading to significant enhancement of bSiO2 relative to organic matter (silicate-pump condition). This may explain why deep export of bSiO2 in this region is elevated by an order of magnitude relative to comparable systems. Diatom carbon, relative to autotrophic carbon, was low (<3%); however, the contribution of Diatoms to new production averaged 3 and 13% using independent approaches. The 4-old discrepancy between methods may be explained by a low average C:Si ratio (∼1.4) for the net produced Diatom C relative to the net produced bSiO2. We speculate that this low production ratio is not the result of reduced C, but may arise from a significant contribution of non-Diatom silicifying organisms to bSiO2 production. The contribution of Diatoms to organic matter export was minor (5.7%). These results, and those of the broader project, suggest substantial food-web transformation of Diatom organic matter in the euphotic zone, which creates enriched bSiO2 relative to organic matter within the exported material.