Articles de revues : « Algal overgrowth »

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Claar, D. C., et M. Takabayashi. « The effects of growth anomaly on susceptibility of Montipora capitata to turf algal overgrowth ». Marine and Freshwater Research 67, n^o 5 (2016) : 666. http://dx.doi.org/10.1071/mf14200.

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One of the most prominent coral diseases in Hawai‘i is growth anomaly (GA) of the skeleton. GA reduces key biological functions of Montipora capitata, but the effect of this disease on the ecological competitiveness of the coral has not been investigated. This study evaluated the effect of the GA on the susceptibility of an endemic Hawaiian coral M. capitata to algal overgrowth at Wai‘ōpae, Hawai‘i. Field surveys and photo analyses were conducted to collect epizootiological data. A relationship was found between GA severity and turf algal growth at the colony level; however, this relationship was weaker than expected. Despite the fact that GA lesions can provide areas of protuberant exposed coral skeleton, turf algal overgrowth was no more prevalent on GA-affected colonies than on unaffected colonies. As algal overgrowth is ephemeral compared to the progression of GA, we suggest that filamentous algae takes advantage of ideal environmental conditions regardless of the availability of new surfaces to invade presented by GA lesions.

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Eich, Andreas, Amanda K. Ford, Maggy M. Nugues, Ryan S. McAndrews, Christian Wild et Sebastian C. A. Ferse. « Positive association between epiphytes and competitiveness of the brown algal genus Lobophora against corals ». PeerJ 7 (8 février 2019) : e6380. http://dx.doi.org/10.7717/peerj.6380.

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Observations of coral–algal competition can provide valuable information about the state of coral reef ecosystems. Here, we report contact rates and apparent competition states for six shallow lagoonal reefs in Fiji. A total of 81.4% of examined coral perimeters were found to be in contact with algae, with turf algae (54.7%) and macroalgae of the genus Lobophora (16.8%) representing the most frequently observed contacts. Turf algae competitiveness was low, with 21.8% of coral–turf contacts being won by the algae (i.e. overgrowth or bleaching of coral tissue). In contrast, Lobophora competitiveness against corals was high, with 62.5% of contacts being won by the alga. The presence of epiphytic algae on Lobophora was associated with significantly greater algal competitiveness against corals, with 75.8% and 21.1% of interactions recorded as algal wins in the presence and absence of epiphytes, respectively. Sedimentation rate, herbivorous fish biomass, and coral colony size did not have a significant effect on Lobophora–coral interactions. This research indicates a novel and important role of epiphytes in driving the outcome of coral–algal contacts.

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Coll, J. C., I. R. Price, G. M. K�nig et B. F. Bowden. « Algal overgrowth of alcyonacean soft corals ». Marine Biology 96, n^o 1 (octobre 1987) : 129–35. http://dx.doi.org/10.1007/bf00394846.

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Lu, Chunrong, Qi Zhang, Qinyu Huang, Shuying Wang, Xiao Qin, Tianfei Ren, Rufeng Xie et Hongfei Su. « Significant Shifts in Microbial Communities Associated with Scleractinian Corals in Response to Algae Overgrowth ». Microorganisms 10, n^o 11 (5 novembre 2022) : 2196. http://dx.doi.org/10.3390/microorganisms10112196.

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Microbes play a key role in reef dynamics, mediating the competition between scleractinian corals and benthic algae; however, major shifts in bacterial communities among coral species in response to increases in the abundance of algae are not well understood. We investigated the taxonomic composition of coral-associated microbial communities under algae-overgrowth conditions using 16S rRNA gene sequencing. The results showed that non-algal (i.e., healthy) tissue (HH) had lower bacterial abundance and diversity than tissue collected from the coral–algae interface boundary (HA) and areas of algae growth (AA). Specifically, the HA and AA samples had higher relative abundances of Saprospiraceae, Rhodobacteraceae, and Alteromonadaceae. Compared with Platygyra sp. and Montipora sp., the physiological response of Pocillopora sp. was more intense under algae-induced stress based on microbial gene function prediction. Our results indicate that algal pressure can significantly alter the microbial community structure and function of coral ecosystems. Our data thus provide new insight into the relationship between corals and their microbiome under environmental stress.

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Jorissen, Hendrikje, Christina Skinner, Ronald Osinga, Dirk de Beer et Maggy M. Nugues. « Evidence for water-mediated mechanisms in coral–algal interactions ». Proceedings of the Royal Society B : Biological Sciences 283, n^o 1836 (17 août 2016) : 20161137. http://dx.doi.org/10.1098/rspb.2016.1137.

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Although many coral reefs have shifted from coral-to-algal dominance, the consequence of such a transition for coral–algal interactions and their underlying mechanisms remain poorly understood. At the microscale, it is unclear how diffusive boundary layers (DBLs) and surface oxygen concentrations at the coral–algal interface vary with algal competitors and competitiveness. Using field observations and microsensor measurements in a flow chamber, we show that coral (massive Porites ) interfaces with thick turf algae, macroalgae, and cyanobacteria, which are successful competitors against coral in the field, are characterized by a thick DBL and hypoxia at night. In contrast, coral interfaces with crustose coralline algae, conspecifics, and thin turf algae, which are poorer competitors, have a thin DBL and low hypoxia at night. Furthermore, DBL thickness and hypoxia at the interface with turf decreased with increasing flow speed, but not when thick turf was upstream. Our results support the importance of water-mediated transport mechanisms in coral–algal interactions. Shifts towards algal dominance, particularly dense assemblages, may lead to thicker DBLs, higher hypoxia, and higher concentrations of harmful metabolites and pathogens along coral borders, which in turn may facilitate algal overgrowth of live corals. These effects may be mediated by flow speed and orientation.

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Picken, Gordon B. « Moray Firth marine fouling communities ». Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 91 (1986) : 213–20. http://dx.doi.org/10.1017/s0269727000009313.

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SynopsisFouling communities typical of shallow water inshore sites were found at three locations in the Moray Firth. At each, an initial background cover of solitary tubeworms and barnacles was overgrown by secondary fouling organisms. On the piles of Nigg jetty, overgrowth consisted of mussels in the depth range 0–6 m and hydroids, sponges, soft corals and anemones from 6–26 m. Buoys in the approaches to Cromarty Firth were completely covered by a mixture of algae and mussels. Sunlit areas of the float cleaned annually bore a diverse algal cover, whereas uncleaned shaded areas and the freely hanging chain had three-year-old mussels up to 7 cm long. Mussel fouling extended down the chain to within 1 m of the seabed at 26 m depth. Concrete anchor blocks on the seabed were covered with solitary tubeworms and hydroids. Steel piled platforms in the Beatrice Field were completely fouled after four years. Mussels and seaweeds were abundant from 0–5 m. In the depth range 8–35 m the background calcareous layer was overgrown by soft corals up to 10 cm long and hydroids. From 35 m to the seabed at 46 m, soft overgrowth was provided mainly by hydroids and ascidians, with only a few small corals.

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Wolf, Alexander T., et Maggy M. Nugues. « Synergistic effects of algal overgrowth and corallivory on Caribbean reef-building corals ». Ecology 94, n^o 8 (août 2013) : 1667–74. http://dx.doi.org/10.1890/12-0680.1.

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Wu, Liming, Huijun Wu, Lina Chen, Shanshan Xie, Haoyu Zang, Rainer Borriss et Xuewen Gao. « Bacilysin from Bacillus amyloliquefaciens FZB42 Has Specific Bactericidal Activity against Harmful Algal Bloom Species ». Applied and Environmental Microbiology 80, n^o 24 (26 septembre 2014) : 7512–20. http://dx.doi.org/10.1128/aem.02605-14.

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ABSTRACTHarmful algal blooms, caused by massive and exceptional overgrowth of microalgae and cyanobacteria, are a serious environmental problem worldwide.In the present study, we looked forBacillusstrains with sufficiently strong anticyanobacterial activity to be used as biocontrol agents. Among 24 strains,Bacillus amyloliquefaciensFZB42 showed the strongest bactericidal activity againstMicrocystis aeruginosa, with a kill rate of 98.78%. The synthesis of the anticyanobacterial substance did not depend on Sfp, an enzyme that catalyzes a necessary processing step in the nonribosomal synthesis of lipopeptides and polyketides, but was associated with thearogene cluster that is involved in the synthesis of thesfp-independent antibiotic bacilysin. Disruption ofbacB, the gene in the cluster responsible for synthesizing bacilysin, or supplementation with the antagonistN-acetylglucosamine abolished the inhibitory effect, but this was restored when bacilysin synthesis was complemented. Bacilysin caused apparent changes in the algal cell wall and cell organelle membranes, and this resulted in cell lysis. Meanwhile, there was downregulated expression ofglmS,psbA1,mcyB, andftsZ—genes involved in peptidoglycan synthesis, photosynthesis, microcystin synthesis, and cell division, respectively. In addition, bacilysin suppressed the growth of other harmful algal species. In summary, bacilysin produced byB. amyloliquefaciensFZB42 has anticyanobacterial activity and thus could be developed as a biocontrol agent to mitigate the effects of harmful algal blooms.

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Diaz-Pulido, Guillermo, Laurence J. McCook, Sophie Dove, Ray Berkelmans, George Roff, David I. Kline, Scarla Weeks, Richard D. Evans, David H. Williamson et Ove Hoegh-Guldberg. « Doom and Boom on a Resilient Reef : Climate Change, Algal Overgrowth and Coral Recovery ». PLoS ONE 4, n^o 4 (22 avril 2009) : e5239. http://dx.doi.org/10.1371/journal.pone.0005239.

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Airoldi, Laura. « EFFECTS OF DISTURBANCE, LIFE HISTORIES, AND OVERGROWTH ON COEXISTENCE OF ALGAL CRUSTS AND TURFS ». Ecology 81, n^o 3 (mars 2000) : 798–814. http://dx.doi.org/10.1890/0012-9658(2000)081[0798:eodlha]2.0.co;2.

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Williams, Claire, Debbie-Ann Gordon-Smith et Pearl Bergan. « Community Abundance and Environmental Monitoring to Support Coral Reef Management in East Portland Special Fishery Conservation Area, Jamaica ». Bulletin of the Florida Museum of Natural History 60, n^o 2 (16 février 2023) : 127. http://dx.doi.org/10.58782/flmnh.iitn6005.

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Global warming and human impacts continue to be devastating for coral reef systems. Jamaican reefs have been adversely affected by a variety of threats including hurricanes, coral bleaching, disease, and algal overgrowth, the impact of which has been exacerbated by global climate change, overfishing, and urchin disease. Despite the dire situation, with proper protection, algal coral phase shifts can be reversed. One area that is being protected is the East Portland Special Fishery Conservation Area (EPSFCA). The EPSFCA is monitored by the Alligator Head Foundation (AHF), which houses a coral nursery, mangrove nursery, and leads monitoring and restoration practices. Although reefs in Jamaica, such as Discovery Bay, were well studied in the 1970s-early 2000s, many ecological studies have not extended to other regions around the island. In particular, the unique reefs of Northeast Jamaica lack data necessary for conservation efforts; no baseline information on community composition had been collected until the establishment of the AHF. To obtain an ecological baseline, this project synthesizes environmental data (nutrient levels, temperature, light) with community assemblage data (fish counts, benthic substrate assessments, and invertebrate counts) from EPSFCA reefs. These sites will be compared using ordinations. To address a longer timeframe of reef evolution, this project will use similar techniques on a fossil reef to see how Caribbean reefs have changed over thousands of years. An analysis of EPSFCA reefs from 2017-2019 found that many sites are distinct, but most reefs show signs of degradation (e.g., high algal cover). Much of the variation between sites can be explained by the abundance of turf algae and the corals Colopophyllia natans, Agaricia grahamae, and Acropora cervicornis. The goal of this project is to combine the EPSFCA data with environmental information to provide a road map for where conservation efforts are likely to support recovery.

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Sordo, Laura, et Paulo Lana. « Temporal variations of Halodule wrightii meadows and associated fauna near their southern distribution limit in the southwestern Atlantic ». Botanica Marina 63, n^o 3 (25 juin 2020) : 215–28. http://dx.doi.org/10.1515/bot-2018-0106.

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AbstractHalodule wrightii meadows in Southern Brazil have been regressing in an unsheltered area of the subtropical Paranaguá Bay, near their southern limit in the SW Atlantic, since 2006. To identify early indicators of regression events, we assessed variations in plant and macrobenthic structure in two local meadows under unsheltered and protected conditions. Differences between sites increased after an epiphytic overgrowth of the alga Hincksia mitchelliae at the unsheltered site. Seagrass growth was suppressed and the numbers of burrowing and opportunistic benthic species increased with the increase of algal biomass. In the protected meadow, seagrass biomass and number of leaves changed seasonally, but macrobenthic abundance and species richness remained stable. Ecosystem changes were evident when the unsheltered meadow was already collapsing. The number of leaves per shoot, the horizontal internode length, the abundance and structure of the macrofaunal associations, and the host-epiphyte surface interactions, were the first variables to reflect the early stages of seagrass regression. Our results suggest that the persistence of H. wrightii meadows at their southern distribution limit in the SW Atlantic will be affected by local hydrodynamics and their ability to compete with ephemeral macroalgal species under stress conditions.

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Wakwella, Ama, Peter J. Mumby et George Roff. « Sedimentation and overfishing drive changes in early succession and coral recruitment ». Proceedings of the Royal Society B : Biological Sciences 287, n^o 1941 (16 décembre 2020) : 20202575. http://dx.doi.org/10.1098/rspb.2020.2575.

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Sedimentation and overfishing are important local stressors on coral reefs that can independently result in declines in coral recruitment and shifts to algal-dominated states. However, the role of herbivory in driving recovery across environmental gradients is often unclear. Here we investigate early successional benthic communities and coral recruitment across a sediment gradient in Palau, Micronesia over a 12-month period. Total sedimentation rates measured by ‘TurfPods’ varied from 0.03 ± 0.1 SE mg cm −2 d −1 at offshore sites to 1.32 ± 0.2 mg cm −2 d −1 at inshore sites. To assess benthic succession, three-dimensional settlement tiles were deployed at sites with experimental cages used to exclude tile access to larger herbivorous fish. Benthic assemblages exhibited rapid transitions across the sediment gradient within three months of deployment. At low levels of sedimentation (less than 0.6 mg cm −2 d −1 ), herbivory resulted in communities dominated by coral recruitment inducers (short turf algae and crustose coralline algae), whereas exclusion of herbivores resulted in the overgrowth of coral inhibitors (encrusting and upright foliose macroalgae). An ‘inducer threshold’ was found under increasing levels of sedimentation (greater than 0.6 mg cm −2 d −1 ), with coral inducers having limited to no presence in communities, and herbivore access to tiles resulted in sediment-laden turf algal assemblages, while exclusion of herbivores resulted in invertebrates (sponges, ascidians) and terrestrial sediment accumulation. A ‘coral recruitment threshold’ was found at 0.8 mg cm −2 d −1 , below which net coral recruitment was reduced by 50% in the absence of herbivores, while recruitment was minimal above the threshold. Our results highlight nonlinear trajectories of benthic succession across sediment gradients and identify strong interactions between sediment and herbivory that have cascading effects on coral recruitment. Local management strategies that aim to reduce sedimentation and turbidity and manage herbivore fisheries can have measurable effects on benthic community succession and coral recruitment, enhancing reef resilience and driving coral recovery.

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Kim, Y., D. R. Lee et D. Giokas. « Agricultural reuse of the secondary effluent polished by an algal pond system coupled with constructed wetland ». Water Science and Technology 50, n^o 6 (1 septembre 2004) : 79–86. http://dx.doi.org/10.2166/wst.2004.0362.

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In this paper, reuse potentials of the secondary effluents as irrigation water was evaluated through field sampling trips. Water quality parameters significantly deviating from its guidelines were Total coliform bacteria and organic matter. Even though nutrients are not regulated in Korea, their removal would be required because they have been a barrier for secondary effluent irrigation through governmental intervention. The results of treatment study with aquatic ponds show that in spite of its poor biodegradability, organic matter in soluble form was reduced by 20% during 10 days of HRT. On the other hand, reduction of nutrients was remarkable. On average 85% of total nitrogen and 89% of total phosphorus were removed, respectively, which abates the worries of farmers for overgrowth or reduction in crop yield. However, coliform bacteria, although slightly reduced due to their propagation at the constructed wetlands still need further treatment.

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Ho, Long T., Duy T. Pham, Wout Van Echelpoel, Andres Alvarado, Juan E. Espinoza-Palacios, Maria B. Arevalo-Durazno et Peter L. M. Goethals. « Exploring the influence of meteorological conditions on the performance of a waste stabilization pond at high altitude with structural equation modeling ». Water Science and Technology 78, n^o 1 (7 juin 2018) : 37–48. http://dx.doi.org/10.2166/wst.2018.254.

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Abstract Algal photosynthesis plays a key role in the removal mechanisms of waste stabilization ponds (WSPs), which is indicated in the variations of three parameters, dissolved oxygen, pH, and chlorophyll a. These variations can be considerably affected by extreme climatic conditions at high altitude. To investigate these effects, three sampling campaigns were conducted in a high-altitude WSP in Cuenca (Ecuador). From the collected data, the first application of structure equation modeling (SEM) on a pond system was fitted to analyze the influence of high-altitude characteristics on pond performance, especially on the three indicators. Noticeably, air temperature appeared as the highest influencing factors as low temperature at high altitude can greatly decrease the growth rate of microorganisms. Strong wind and large diurnal variations of temperature, 7–20 °C, enhanced flow efficiency by improving mixing inside the ponds. Intense solar radiation brought both advantages and disadvantages as it boosted oxygen level during the day but promoted algal overgrowth causing oxygen depletion during the night. From these findings, the authors proposed insightful recommendations for future design, monitoring, and operation of high-altitude WSPs. Moreover, we also recommended SEM to pond engineers as an effective tool for better simulation of such complex systems like WSPs.

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Nezbrytska, Inna, Oleg Usenko, Igor Konovets, Tetiana Leontieva, Igor Abramiuk, Mariia Goncharova et Olena Bilous. « Potential Use of Aquatic Vascular Plants to Control Cyanobacterial Blooms : A Review ». Water 14, n^o 11 (27 mai 2022) : 1727. http://dx.doi.org/10.3390/w14111727.

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Intense “blooming” of cyanobacteria (blue-green algae) caused by eutrophication and climate change poses a serious threat to freshwater ecosystems and drinking water safety. Preventing the proliferation of cyanobacteria and reducing water nutrient load is a priority for the restoration of eutrophic water bodies. Aquatic plants play an important role in the function and structure of aquatic ecosystems, affecting the physiochemistry of the water and bottom sediments, primary production, and biotic interactions that support a balanced ecosystem. This review examines the inhibitory effect of aquatic vascular plants on harmful blooms of cyanobacteria. Aquatic plants are able to successfully inhibit the growth of cyanobacteria through various mechanisms, including by reducing nutrient and light availability, creating favorable conditions for the development of herbivorous zooplankton, and releasing allelopathic active substances (allelochemicals) with algicidal effect. Allelopathy is species-specific and therefore acts as one of the key mechanisms by which the development of cyanobacterial populations in aquatic ecosystems is regulated. However, allelopathic activity of aquatic vascular plants depends on various factors (species characteristics of aquatic plants, area, and density of overgrowth of water bodies, physiochemical properties of allelopathically active substances, hydrological and hydrochemical regimes, temperature, light intensity, etc.), which may regulate the impact of allelochemicals on algal communities. The paper also discusses some problematic aspects of using fast-growing species of aquatic vascular plants to control cyanobacterial blooms.

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Olena, Bilous, Nezbrytska Inna, Zhezherya Vladyslav, Dubniak Serhii, Batoh Svitlana, Kazantsev Taras, Polishchuk Oleksandr, Zhezherya Tetyana, Leontieva Tetyana et Cantonati Marco. « Interactions between Aquatic Plants and Cyanobacterial Blooms in Freshwater Reservoir Ecosystems ». Water 15, n^o 4 (8 février 2023) : 672. http://dx.doi.org/10.3390/w15040672.

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Climate change and nutrient pollution are echoed by worldwide increasing trends in the frequency, duration, and toxicity of cyanobacterial (blue-green algal) blooms. Therefore, searching for the best options to mitigate blooms is relevant and timely. Aquatic vascular plants offer a promising solution through biological control. In this study, we use reservoirs regularly affected by intensive blooms (the Kyiv and Kaniv Reservoirs of the Dnipro River, Ukraine) to investigate whether macrophytes may inhibit or reduce the massive development of cyanobacteria. Special attention was paid to plants with floating leaves and free-floating plants since data on their effects on cyanobacteria are controversial. On the basis of field and satellite observations, the spatial distribution of cyanobacterial blooms and aquatic macrophyte patches was assessed. Multispectral images captured by satellites Sentinel-2a (S2A) and Sentinel-2b (S2B) were used. In addition, based on data from field observations, a comparative analysis of phytoplankton and physical and chemical parameters between areas of the reservoirs overgrown and not overgrown by macrophytes was carried out. The obtained results indicate that in macrophyte patches phytoplankton structure differed from that observed in open waters. However, in areas of reservoirs dominated by floating-leaf plants or free-floating plants, a significant decrease in phytoplanktic or cyanobacterial biomass was not observed. This is most likely due to the fact that these macrophytes did not reduce the concentration of biogenic substances to a level that would limit cyanobacterial growth. On the contrary, intensive overgrowth of floating-leaf plants (in particular, Trapa natans) along the river sections of the reservoirs, as well as other factors, contributed to nitrogen and phosphorus enrichment. Therefore, in the face of relevant nutrient supply, these ecological groups of macrophytes (floating-leaf plants and free-floating plants) have not shown statistically significant effectiveness in controlling the process of cyanobacterial blooms in reservoir ecosystems.

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Pacheco, Diana, Glacio Souza Araújo, João Cotas, Rui Gaspar, João M. Neto et Leonel Pereira. « Invasive Seaweeds in the Iberian Peninsula : A Contribution for Food Supply ». Marine Drugs 18, n^o 11 (16 novembre 2020) : 560. http://dx.doi.org/10.3390/md18110560.

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The introduction of exotic organisms in marine ecosystems can lead to economic and ecological losses. Globally, seaweeds represent a significant part of these non-indigenous species (NIS), with 407 introduced algal species. Furthermore, the presence of NIS seaweeds has been reported as a major concern worldwide since the patterns of their potential invasion mechanisms and vectors are not yet fully understood. Currently, in the Iberian Peninsula, around 50 NIS seaweeds have been recorded. Some of these are also considered invasive due to their overgrowth characteristic and competition with other species. However, invasive seaweeds are suitable for industrial applications due to their high feedstock. Hence, seaweeds’ historical use in daily food diet, allied to research findings, showed that macroalgae are a source of nutrients and bioactive compounds with nutraceutical properties. The main goal of this review is to evaluate the records of NIS seaweeds in the Iberian Peninsula and critically analyze the potential of invasive seaweeds application in the food industry.

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Zhang, Shanshan, Xiaoqi He, Lei Cao, Yigang Tong, Baohua Zhao et Wenlin An. « A Novel Wide-Range Freshwater Cyanophage MinS1 Infecting the Harmful Cyanobacterium Microcystis aeruginosa ». Viruses 14, n^o 2 (20 février 2022) : 433. http://dx.doi.org/10.3390/v14020433.

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Microcystis aeruginosa, as one of the major players in algal bloom, produces microcystins, which are strongly hepatotoxic, endangering human health and damaging the ecological environment. Biological control of the overgrowth of Microcystis with cyanophage has been proposed to be a promising solution for algal bloom. In this study, a novel strain of Microcystis cyanophage, MinS1, was isolated. MinS1 contains an icosahedral head approximately 54 nm in diameter and a 260 nm-long non-contractile tail. The phage genome consists of a linear, double-stranded 49,966 bp DNA molecule, which shares very low homology with known phages in the NCBI database (only 1% of the genome showed weak homology with known phages when analyzed by megablast). The phage contains 75 ORFs, of which 23 ORFs were predicted to code for proteins of known function, 39 ORFs were predicted to code for proteins of unknown function, and 13 ORFs showed no similarity to any protein sequences. Transmission electron microscopy and phylogenetic analysis showed that MinS1 belongs to the family Siphoviridae. Various experiments confirmed that the phage could infect several different orders of cyanobacteria, including Chroococcales, Nostocales, Oscillatoriales, Hormogonales, and Synechococcales, indicating that it has a very broad host range. In addition, MinS1 has no known antibiotic tolerance genes, virulence genes, and tRNAs, and it is tolerant to temperature, pH, UV, and salinity, suggesting that MinS1 has good potential for application as a biological control agent against cyanobacterial blooms. This study expands the diversity and knowledge of cyanophages, and it provides useful information for the development of novel prevention and control measures against cyanobacterial blooms.

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Montano, Simone, Simone Fattorini, Valeriano Parravicini, Michael L. Berumen, Paolo Galli, Davide Maggioni, Roberto Arrigoni, Davide Seveso et Giovanni Strona. « Corals hosting symbiotic hydrozoans are less susceptible to predation and disease ». Proceedings of the Royal Society B : Biological Sciences 284, n^o 1869 (20 décembre 2017) : 20172405. http://dx.doi.org/10.1098/rspb.2017.2405.

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In spite of growing evidence that climate change may dramatically affect networks of interacting species, whether—and to what extent—ecological interactions can mediate species' responses to disturbances is an open question. Here we show how a largely overseen association such as that between hydrozoans and scleractinian corals could be possibly associated with a reduction in coral susceptibility to ever-increasing predator and disease outbreaks. We examined 2455 scleractinian colonies (from both Maldivian and the Saudi Arabian coral reefs) searching for non-random patterns in the occurrence of hydrozoans on corals showing signs of different health conditions (i.e. bleaching, algal overgrowth, corallivory and different coral diseases). We show that, after accounting for geographical, ecological and co-evolutionary factors, signs of disease and corallivory are significantly lower in coral colonies hosting hydrozoans than in hydrozoan-free ones. This finding has important implications for our understanding of the ecology of coral reefs, and for their conservation in the current scenario of global change, because it suggests that symbiotic hydrozoans may play an active role in protecting their scleractinian hosts from stresses induced by warming water temperatures.

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Seveso, Davide, Simone Montano, Giovanni Strona, Ivan Orlandi, Marina Vai et Paolo Galli. « Up-regulation of Hsp60 in response to skeleton eroding band disease but not by algal overgrowth in the scleractinian coral Acropora muricata ». Marine Environmental Research 78 (juillet 2012) : 34–39. http://dx.doi.org/10.1016/j.marenvres.2012.03.008.

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Olinger, LK, A. Chaves-Fonnegra, IC Enochs et ME Brandt. « Three competitors in three dimensions : photogrammetry reveals rapid overgrowth of coral during multispecies competition with sponges and algae ». Marine Ecology Progress Series 657 (7 janvier 2021) : 109–21. http://dx.doi.org/10.3354/meps13579.

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Competition for limited space is an important driver of benthic community structure on coral reefs. Studies of coral-algae and coral-sponge interactions often show competitive dominance of algae and sponges over corals, but little is known about the outcomes when these groups compete in a multispecies context. Multispecies competition is increasingly common on Caribbean coral reefs as environmental degradation drives loss of reef-building corals and proliferation of alternative organisms such as algae and sponges. New methods are needed to understand multispecies competition, whose outcomes can differ widely from pairwise competition and range from coexistence to exclusion. In this study, we used 3D photogrammetry and image analyses to compare pairwise and multispecies competition on reefs in the US Virgin Islands. Sponges (Desmapsamma anchorata, Aplysina cauliformis) and macroalgae (Lobophora variegata) were attached to coral (Porites astreoides) and arranged to simulate multispecies (coral-sponge-algae) and pairwise (coral-sponge, coral-algae) competition. Photogrammetric 3D models were produced to measure surface area change of coral and sponges, and photographs were analyzed to measure sponge-coral, algae-coral, and algae-sponge overgrowth. Coral lost more surface area and was overgrown more rapidly by the sponge D. anchorata in multispecies treatments, when the sponge was also in contact with algae. Algae contact may confer a competitive advantage to the sponge D. anchorata, but not to A. cauliformis, underscoring the species-specificity of these interactions. This first application of photogrammetry to study competition showed meaningful losses of living coral that, combined with significant overgrowths by competitors detected from image analyses, exposed a novel outcome of multispecies competition.

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Patel, Ruchit, Aline de Oliveira, Robert Newby et Tinchun Chu. « Flow Cytometric Analysis of Freshwater Cyanobacteria : A Case Study ». Water 11, n^o 7 (11 juillet 2019) : 1422. http://dx.doi.org/10.3390/w11071422.

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Eutrophication is a process that occurs due to the excessive accumulation of nutrients, primarily nitrogen and phosphorus, from natural and anthropogenic sources. This phenomenon causes cyanobacterial overgrowth, which over time leads to cyanobacterial harmful algal blooms (CHABs) that affect public drinking water sources and water sites with recreational usage. The rapid detection of bloom-forming cyanobacteria in freshwater bodies is critical in order to implement prevention strategies. Cyanobacteria contain phycobiliproteins such as phycoerythrin and allophycocyanin as part of the phycobilisome that allows autofluorescence. In this study, samples from 36 freshwater bodies in 14 New Jersey counties were collected and analyzed using flow cytometry with forward-scatter phycoerythrin and allophycocyanin parameters. Pure cultures of Synechococcus sp. IU 625, Cylindrospermum spp. and Microcystis aeruginosa were used as references. The results revealed that 17 out of the 36 analyzed sites contained all three references and related species. Seven sites showed Microcystis and Cylindrospermum-like species, while four sites indicated Microcystis and Cylindrospermum-like species. Six water bodies showed Cylindrospermum-like species, and two sites showed Microcystis-like species. Polymerase chain reaction (PCR)-based assays further confirmed the flow cytometric results. The findings from this study suggest that flow cytometry could potentially serve as a rapid method for freshwater cyanobacteria detection and screening.

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Work, TM, E. Millard, DB Mariani, TM Weatherby, RA Rameyer, J. Dagenais, R. Breeden et AM Beale. « Cytology reveals diverse cell morphotypes and cellin-cell interactions in normal collector sea urchins Tripneustes gratilla ». Diseases of Aquatic Organisms 142 (19 novembre 2020) : 63–73. http://dx.doi.org/10.3354/dao03533.

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Echinoderms such as sea urchins are important in marine ecosystems, particularly as grazers, and unhealthy sea urchins can have important ecological implications. For instance, unexplained mortalities of Diadema antillarum in the Caribbean were followed by algal overgrowth and subsequent collapse of coral reef ecosystems. Unfortunately, few tools exist to evaluate echinoderm health, making management of mortalities or other health issues problematic. Hematology is often used to assess health in many animal groups, including invertebrates, but is seldom applied to echinoderms. We used a standard gravitometric technique to concentrate fixed coelomocytes from the collector sea urchin Tripneustes gratilla onto microscope slides, permitting staining and enumeration. Using Romanowsky stain and electron microscopy to visualize cell details, we found that urchin cells could be partitioned into different morphotypes. Specifically, we enumerated phagocytes, phagocytes with perinuclear cytoplasmic dots, vibratile cells, colorless spherule cells, red spherule cells, and red spherule cells with pink granules. We also saw cell-in-cell interactions characterized by phagocytes apparently phagocytizing mainly the motile cells including red spherule cells, colorless spherule cells, and vibratile cells disproportionate to underlying populations of circulating cells. Cell-in-cell interactions were seen in 71% of sea urchins, but comprised <1% of circulating cells. Finally, about 40% of sea urchins had circulating phagocytes that were apparently phagocytizing spicules. The coelomic fluid collection and slide preparation methods described here are simple, field portable, and might be a useful complementary tool for assessing health of other marine invertebrates, revealing heretofore unknown physiological phenomena in this animal group.

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Nakamura, Shuji. « InGaN/GaN/AlGaN-based laser diodes grown on epitaxially laterally overgrown GaN ». Journal of Materials Research 14, n^o 7 (juillet 1999) : 2716–31. http://dx.doi.org/10.1557/jmr.1999.0365.

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Epitaxially laterally overgrown GaN on sapphire was used to reduce the number of threading dislocations originating from the interface of the GaN epilayer with the sapphire substrate. The GaN layer above the SiO2 mask area surrounding the window and corresponding to the lateral overgrowth was nearly free of threading dislocations. A high density of threading dislocations was observed in the vicinity of GaN grown in the window regions. InGaN multiquantum well-structure laser diodes (LDs) grown on pure GaN substrates, which were fabricated by removing the sapphire substrate, were demonstrated. The LDs with an output power of 5 mW exhibited a lifetime of more than 290 h and an estimated lifetime of 10,000 h despite a relatively large threshold current density. The far-field pattern of the LDs with a cleaved mirror facet revealed single-mode emission without any interference effects.

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Setiabudi, Gede Iwan, Dietriech G. Bengen, Ocky Karna Radjasa et Hefni Effendi. « Preliminary study of algasidal activities of the episymbiont bacterial consortium from Enhalus acoroides ». Advances in Tropical Biodiversity and Environmental Sciences 2, n^o 2 (10 décembre 2018) : 21. http://dx.doi.org/10.24843/atbes.2018.v02.i02.p02.

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Seagrass symbiotic bacteria have various functions, one of which is as algaside. There are 2 types of symbionts namely endosymbiont and episymbiont. This study aims to test the initial activity of algaside episymbiont Enhalus acoroides on diatome and dinoflagellate group plankton. The method used for testing is Mixed Algal-bacterial cultures. On media that has been overgrown with algae will be inoculated with episymbiont bacterial consortium E. acoroides. The results of the bacterial consortium research have not shown significant algaside activity. But, on Nitschia sp. showed significant algaside activity. This mean specific activity in the compound or mechanism used as algaside.

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Lazarev, S., M. Barchuk, S. Bauer, K. Forghani, V. Holý, F. Scholz et T. Baumbach. « Study of threading dislocation density reduction in AlGaN epilayers by Monte Carlo simulation of high-resolution reciprocal-space maps of a two-layer system ». Journal of Applied Crystallography 46, n^o 1 (8 décembre 2012) : 120–27. http://dx.doi.org/10.1107/s0021889812043051.

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High-resolution X-ray diffraction in coplanar and noncoplanar geometries has been used to investigate the influence of an SiNxnano-mask in the reduction of the threading dislocation (TD) density of high-quality AlGaN epitaxial layers grown on sapphire substrates. Our developed model, based on a Monte Carlo method, was applied to the simulation of the reciprocal-space maps of a two-layer system. Good agreement was found between the simulation and the experimental data, leading to an accurate determination of the dislocation densities as a function of the overgrowth layer thickness. The efficiency of the SiNxnano-mask was defined as the ratio of the TD densities in the AlGaN layers below and above the mask. A significant improvement in the AlGaN layer quality was achieved by increasing the overgrowth layer thickness, and a TD density reduction scaling law was established.

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Martín-Closas, Carles. « Epiphytic Overgrowth of Charophyte Thalli by Stromatolite-like Structures and Fungi in the Lower Cretaceous of the Iberian Ranges (Spain) ». Australian Journal of Botany 47, n^o 3 (1999) : 305. http://dx.doi.org/10.1071/bt97098.

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The Lower Cretaceous (113 million years old) lacustrine deposits of Las Hoyas(Iberian Ranges, Cuenca, Spain) yield an epiphytic assemblage formed by thecharophyte species Clavatoraxis diaz-romeraliiMartín-Closas & Diéguez overgrown by a muddy, laminatedstromatolite-like structure. Fossil charophyte thalli coated with biogeniclaminations were previously unknown from the fossil record. Within thisstromatolite-like structure, filaments are found which correspond to thalli ofanother charophyte, Palaeonitella vermicularisMartín-Closas & Diéguez, and to septate hyphae of fungi(Ascomycetes). The distribution pattern of the biogenic lamination and itsselective growth only on the strongest thalli ofClavatoraxis diaz-romeralii suggests that it occurredwhen these macrophytes were still alive, standing upright on the lake bottom.From this point of view the stromatolite-like structures are reminiscent ofextant overgrowths of charophyte thalli by epiphytic, filamentouscyanobacteria, eucaryotic algae and fungi. These assemblages appear to developafter eutrophication of nutrient-poor environments, which are more suitablefor charophyte growth.

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Lapointe, B. E., B. J. Bedford, M. M. Littler et D. S. Littler. « Shifts in coral overgrowth by sponges and algae ». Coral Reefs 26, n^o 3 (23 mai 2007) : 515. http://dx.doi.org/10.1007/s00338-007-0242-x.

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Mienasova, A. Sh. « MOST ANCIENT PODOLIA’S ALGAE AS TRIGGER FOR THE FORMATION OF PHOSPHORITES ». Мінеральні ресурси України, n^o 1 (25 avril 2019) : 21–25. http://dx.doi.org/10.31996/mru.2019.1.21-25.

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The phosphorites are rather widely represented in platform carbonate and quartz-glauconite litho-tectonic complexes. They are also present in Kalyus Beds of Nagoryany Formation in Podolian Middle Dnister area.These beds are folded by homogeneous, dark-grey to black, thin-bedded mudstones. Characteristic feature of the beds is the occurrence of phosphorite concretions of different sizes. Dispersed phosphate mineralization (4–30 %) is also present in mudstones. Kalyus Beds have two levels enriched by remains of Vendotaenian algae. Lower level is located in the bottom surface and upper level is located near top surface. It is the most ancient and numerous imprints of algae in rocks of Upper Vendian. According to the general appearance of thalli, the nature of sporangia and the type of metabolism, they are referred to as brown algae, which were adopting a benthic lifestyle. And they include an assemblage of microphytofossils too. The black color, the presence of globular pyrite, the bitumen interlayers and the value of the protoxid module – 1,32–1,83 indicate the conditions for sedimentation recovery. Algal textures say that sedimentation occurred in the euphotic zone, that is, at the depth of light penetration. This is confirmed by the ecology of modern brown algae, which live from the low-water line to a depth of 20–30 m.In the Late Vendian, there was no terrestrial vegetation, therefore sloping substrates eroded much faster and the land was a vast plain almost at the level of the water’s edge. The coastline (in the modern sense) didn’t exist, it constantly migrated and this led to the fact that in the “coastal zone” formed numerous gulfs, overgrown with algae. The main source of phosphorus was the weathering crust of the subsilicic tuffogenic rocks with a high content of Р2О5. Then, phosphoric compounds fell into the sedimentation basin and assimilated by cyanobacteria and algae in the form of polyphosphoric acids. Cyanobacterial communities had multidirectional vectors of their life activity, so ones created various biochemical barriers. Acidic medium was for dissolving apatite and/or francolite, and then alkaline one, which was necessary for phosphorus precipitation. In addition, phosphorus could be precipitated as a result of seasonal fluctuations in temperature, which led to departure of the chemical equilibrium. Also algal films and microbiofilm could hold phosphorus-containing pelitic particles on their surfaces.Land vegetation cover absent, therefore the coastline constantly migrated so the primary structure of algal mats and biofilms were periodically disturbed. They were rolling, sticking, etc. took place. As a result, thrombolytics (nonlayered clot structures) were formed. Further lithification takes place under reducing conditions at the bottom and at the top of the sediment. If the concentration of phosphorus is high in sludge waters, phosphorite concretions can form from thrombolites then.

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Ruitton, Sandrine, Aurélie Blanfuné, Charles-François Boudouresque, Dorian Guillemain, Valérie Michotey, Sylvain Roblet, Delphine Thibault, Thierry Thibaut et Marc Verlaque. « Rapid Spread of the Invasive Brown Alga Rugulopteryx okamurae in a National Park in Provence (France, Mediterranean Sea) ». Water 13, n^o 16 (23 août 2021) : 2306. http://dx.doi.org/10.3390/w13162306.

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The temperate Northwest Pacific brown alga Rugulopteryx okamurae (Dictyotales, Phaeophyceae) was first discovered in 2002 in the Mediterranean Sea in the Thau coastal lagoon (Occitania, France) and then again in 2015 along the southern side of the Strait of Gibraltar, where it was assigned with invasive status. We report here on the first occurrence of the species in the Northwest Mediterranean Sea in Calanques National Park (Marseille, France) in 2018. By 2020, a large population had developed, extending over 9.5 km of coastline, including highly protected no-take zones. The seafood trade, with R. okamurae used as packing material for sea urchin Paracentrotus lividus shipments from Thau Lagoon, could be the vector of its introduction into the Marseille area. As observed in the Strait of Gibraltar, R. okamurae is spreading rapidly along the Marseille coasts, suggesting an invasive pathway. The subtidal reefs are densely carpeted with R. okamurae, which overgrows most native algal species. Fragments of the alga are continuously detached by wave actions and currents, sedimenting on the seabed and potentially clogging fishing nets, and thus, impacting artisanal fishing or washing up on the beaches, where they rot and raise concern among local populations.

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Rovellini, Alberto, Matthew R. Dunn, Elizabeth A. Fulton, Lisa Woods, Jamaluddin Jompa, Abdul Haris et James J. Bell. « Interannual variability and decadal stability of benthic organisms on an Indonesian coral reef ». Journal of the Marine Biological Association of the United Kingdom 101, n^o 2 (mars 2021) : 221–31. http://dx.doi.org/10.1017/s0025315421000291.

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AbstractThe availability of colonizable substrate is an important driver of the temporal dynamics of sessile invertebrates on coral reefs. Increased dominance of algae and, in some cases, sponges has been documented on many coral reefs around the world, but how these organisms benefit from non-colonized substrate on the reef is unclear. In this study, we described the temporal dynamics of benthic organisms on an Indonesian coral reef across two time periods between 2006 and 2017 (2006–2008 and 2014–2017), and investigated the effects of colonizable substrate on benthic cover of coral reef organisms at subsequent sampling events. In contrast with other Indonesian reefs where corals have been declining, corals were dominant and stable over time at this location (mean ± SE percentage cover 42.7 ± 1.9%). Percentage cover of turf algae and sponges showed larger interannual variability than corals and crustose coralline algae (CCA) (P < 0.001), indicating that these groups are more dynamic over short temporal scales. Bare substrate was a good predictor of turf cover in the following year (mean effect 0.2, 95% CI: 0–0.4). Algal cover combined with bare space was a good predictor of CCA cover the following year generally, and of sponge cover the following year but only at one of the three sites. These results indicate that turf algae on some Indonesian reefs can rapidly occupy free space when this becomes available, and that other benthic groups are probably not limited by the availability of bare substrate, but may overgrow already fouled substrates.

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Bulleri, F. « Duration of overgrowth affects survival of encrusting coralline algae ». Marine Ecology Progress Series 321 (8 septembre 2006) : 79–85. http://dx.doi.org/10.3354/meps321079.

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Mu, Xinan, et Robert Riding. « Silicification of Permian calcareous algae from Nanjing, China ». Geological Magazine 125, n^o 2 (mars 1988) : 123–39. http://dx.doi.org/10.1017/s0016756800009535.

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AbstractCalcareous algae in limestones of the Permian Chihsia Formation near Nanjing, China, are preferentially replaced by quartz. Replacement postdates both cementation by sparry calcite and also neomorphic alteration of the original skeletons to sparry calcite. It is thus diagenetically relatively late. The original replacement silica could have been massive opal CT, opal CT lepispheres, or quartz. Lepisphere-like bodies occur in a few specimens. Megaquartz rims represent later overgrowths on the silicified skeletons. Although the original ultrastructure of the algal skeletons is not preserved, the preferential silicification allows fine details of the skeletal morphology of the algae to be observed and the distribution of silica indicates the style of replacement which has probably occurred. In some specimens it is possible that dissolution of the skeleton was followed by void-filling by silica, including the possibility of lepisphere formation. But in other cases in situ replacement, probably by massive opal CT or quartz, is reflected by the replacement of the outer parts of calcite crystals by silica. This process produces a network of silica, and as it proceeds the calcite centres of the grains become progressively smaller until silica replacement is complete. Sponge spicules may have provided the most important silica source for replacement. It is proposed that water-insoluble organic films surrounding matrix grains, and now preserved as bituminous material, protected the matrix from replacement thus promoting selective late diagenetic silicification of these fossils.

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El Rahimi, S. A., E. Hendra, A. Isdianto et O. M. Luthfi. « Feeding preference of herbivorous fish : Family Scaridae ». IOP Conference Series : Earth and Environmental Science 869, n^o 1 (1 novembre 2021) : 012004. http://dx.doi.org/10.1088/1755-1315/869/1/012004.

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Abstract Parrotfish is one of dominant species in Indo-Pacific areas which have 9 genera and 83 species. In ecological perspective, the feeding behaviours of these fish very important, due to control population of algae in coral reef ecosystem. They used their jaw to excavate and scrape alga which living on coral substrata, so sometime resulted on erosion in substrates and coral. The aim of this research to record the diet preference of Scariids fish in NCF Putri Menjangan conservation area, Bali on January to february 2020. Group of Scariids fish was recorded by underwater camera for one minute then the bites scared were calculated manually and photographed. The result of study showed that 10 species from two genera (Chlorurus and Scarus) was dominantly herbivorous fish in this area. The highest number of fish bites at station 1 was obtained from S. qouyi species with a total of 41.27 bpm, while stations 2 and 3 were obtained from S. rivulatus species with a number of 40.96 bpm and 41.59 bpm, respectively. The majority of parrotfish species found chose to forage on dead coral with algae substrates because the water conditions were not optimal for the growth of coral, so many corals died and their skeletons were overgrown by algae.

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Matsuoka, R., T. Okimoto, K. Nishino, Y. Naoi et S. Sakai. « AlGaN epitaxial lateral overgrowth on Ti-evaporated GaN/sapphire substrate ». Journal of Crystal Growth 311, n^o 10 (mai 2009) : 2847–49. http://dx.doi.org/10.1016/j.jcrysgro.2009.01.027.

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Ulfah, Maria, Iqbal Nindo Turnip, Chitra Octavina, Irma Dewiyanti et Syahrul Purnawan. « Prevalence and abundance of coral disease in Aceh Besar regency Aceh, Indonesia ». Depik 11, n^o 3 (31 octobre 2022) : 490–96. http://dx.doi.org/10.13170/depik.11.3.26593.

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The aims of this research was to knew the prevalence, abundance and types of coral diseases detected in Peukan Bada Aceh Besar Regency. Method used in this research was a 20x2m belt transect with 3 replicates. Results show that the prevalence value was between 27,94% – 58,25%. The value was quite higher if compared with other prevalence on some place in indonesia. Average value of coral disease abundance in this research was 0,23 ind/m2. There was 13 types of coral disease found during sampling, including Fish Bite, Drupella Predation, Acanthaster planci Predation, White Syndrome, Ulcerative White Spot, Focal Bleaching, Non-Focal Bleaching, Invertebrate Galls, Sponge Overgrowth, Cyanobacteria, Pigmentation Response, Sedimentation Damage, Algae Overgrowth. The most infected coral genus was Acropora with branching growth form.Keywords:AbundanceConditionCoral diseasePrevalence

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Allerman, A. A., M. H. Crawford, S. R. Lee et B. G. Clark. « Low dislocation density AlGaN epilayers by epitaxial overgrowth of patterned templates ». Journal of Crystal Growth 388 (février 2014) : 76–82. http://dx.doi.org/10.1016/j.jcrysgro.2013.11.052.

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Liu, R., A. Bell, F. A. Ponce, H. Amano, I. Akasaki et D. Cherns. « Thick crack-free AlGaN films deposited by facet-controlled epitaxial lateral overgrowth ». physica status solidi (c), n^o 7 (décembre 2003) : 2136–40. http://dx.doi.org/10.1002/pssc.200303450.

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Underwood, A. J. « Why overgrowth of intertidal encrusting algae does not always cause competitive exclusion ». Journal of Experimental Marine Biology and Ecology 330, n^o 2 (mars 2006) : 448–54. http://dx.doi.org/10.1016/j.jembe.2005.09.005.

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Rudziński, Mariusz, Sebastian Zlotnik, Marek Wójcik, Jarosław Gaca, Łukasz Janicki et Robert Kudrawiec. « Mask-free three-dimensional epitaxial growth of III-nitrides ». Journal of Materials Science 56, n^o 1 (1 octobre 2020) : 558–69. http://dx.doi.org/10.1007/s10853-020-05187-0.

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Abstract A novel catalyst-free and maskless growth approach is presented to form an ordered geometrical array of three-dimensional (3D) AlGaN/AlN microrods. The growth method is composed of a single growth step using metalorganic vapor phase epitaxy, achieving microstructures with homogeneous diameters, shapes and sizes over relatively large scale (on 2-in. wafer). The 3D AlGaN/AlN heterostructures are grown in a form of micro-sized columns elongated in one direction perpendicular to the substrate surface and with a hexagonal cross section. A careful examination of growth steps revealed that this technology allows to suppress coalescence and lateral overgrowth, promoting vertical 3D growth. Interestingly, two distinct morphologies can be obtained: honeycomb-like hexagonal arrangement perfectly packed and with twisted microrods layout, by controlling strain state in AlN buffer layers. Consequently, 3D AlGaN microrods on tensile-strained AlN templates show a 0° twisted morphology, while on compressive-strained templated a 30° twisted arrangement. Moreover, the optical and crystalline quality studies revealed that the top AlGaN layers of the examined 3D semiconductor structures are characterized by a low native point-defect concentration. These 3D AlGaN platforms can be applied for light emitting devices or sensing applications. Graphic abstract

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D Marsh, Philip. « Do dental diseases resemble ecological catastrophes ? » Microbiology Australia 26, n^o 3 (2005) : 102. http://dx.doi.org/10.1071/ma05102.

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Ecological catastrophes can take many forms, and can come in all shapes and sizes! Nitrogenous fertilisers can be washed off farm-land into lakes and ponds, resulting in overgrowth by algae. Such an overgrowth can lead to secondary effects to the ecosystem; the algae can consume dissolved oxygen in the water leading to the loss of aerobic microbial, plant and insect life (eutrophication). Similarly, atmospheric pollution with sulphur dioxide and nitrogen oxides can produce acid rain causing damage to plants and trees and loss of aquatic life. On a larger scale, it has been postulated that the extinction of the dinosaurs followed climate change resulting from the impact of a meteorite. At the other end of the spectrum, it will be argued in this article that the key to a more complete understanding of the role of micro-organisms in dental diseases depends on a paradigm shift away from concepts that have evolved from studies of diseases with a simple and specific (e.g. single species) aetiology to an appreciation of ecological principles similar to those outlined above, where a substantial change to a key parameter influencing the habitat can disrupt the natural balance of the resident oral microflora. Acceptance of such principles can more readily explain the transition of the oral microflora from having a benign to a pathogenic relationship with the host, while opening up new opportunities for the control of dental plaque-mediated diseases.

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Hofmann, L., A. Knauer, I. Rechenberg et M. Weyers. « Overgrowth of trenches with (AlGa)As using metalorganic vapor-phase epitaxy (MOVPE) ». Journal of Crystal Growth 195, n^o 1-4 (décembre 1998) : 485–89. http://dx.doi.org/10.1016/s0022-0248(98)00575-2.

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Fleischmann, Simon, Sylvia Hagedorn, Anna Mogilatenko, Jonas Weinrich, Deepak Prasai, Eberhard Richter, Ralph-Stephan Unger, Markus Weyers et Günther Tränkle. « Designing sapphire surface patterns to promote AlGaN overgrowth in hydride vapor phase epitaxy ». Semiconductor Science and Technology 35, n^o 3 (25 février 2020) : 035028. http://dx.doi.org/10.1088/1361-6641/ab7148.

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Bell, A., R. Liu, U. K. Parasuraman, F. A. Ponce, S. Kamiyama, H. Amano et I. Akasaki. « Spatial variation of luminescence from AlGaN grown by facet controlled epitaxial lateral overgrowth ». Applied Physics Letters 85, n^o 16 (18 octobre 2004) : 3417–19. http://dx.doi.org/10.1063/1.1807950.

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Mogilatenko, Anna, Viola Küller, Arne Knauer, J. Jeschke, Ute Zeimer, Markus Weyers et Günther Tränkle. « Defect analysis in AlGaN layers on AlN templates obtained by epitaxial lateral overgrowth ». Journal of Crystal Growth 402 (septembre 2014) : 222–29. http://dx.doi.org/10.1016/j.jcrysgro.2014.06.025.

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Rabinowitz, Sarah, et Joshua Solano. « When the Red Tide Rolls In : A Red Tide Associated Angioedema Case Report ». Clinical Practice and Cases in Emergency Medicine 2, n^o 5 (13 avril 2021) : 222–25. http://dx.doi.org/10.5811/cpcem.2021.3.51920.

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Introduction: Histamine-mediated angioedema is a potentially life-threatening reaction following exposures that incite mast cell activation. In Florida, red tides are a frequent phenomenon caused by overgrowth of the harmful algae species Karenia brevis, which contain environmentally detrimental brevetoxins. Even in low concentrations, brevetoxins can cause disease in humans through inducing histamine release. We report the first documented case of angioedema associated with red tide exposure. Case Report: A 52-year-old-male presented with severe angioedema encompassing both lips within a few hours after exposure to red tide algae. Other symptoms included voice changes and difficulty swallowing. Laboratory findings revealed complement factors that were within reference range, which ruled out a bradykinin-mediated pathology and supported the diagnosis of histaminergic angioedema. Symptoms resolved after 24 hours in the intensive care unit under management with epinephrine, diphenhydramine, methylprednisolone, and famotidine. Conclusion: In coastal regions, red tide algae should be recognized as a rare cause of acute angioedema. Emergency management of histamine-mediated angioedema should focus on preventing respiratory compromise with frequent airway monitoring and treatment with steroids, antihistamines, and epinephrine.

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Yusuf, Yusnizam, Muhammad Esmed Alif Samsudin, Muhamad Ikram Md Taib, Mohd Anas Ahmad, Mohamed Fauzi Packeer Mohamed, Hiroshi Kawarada, Shaili Falina, Norzaini Zainal et Mohd Syamsul. « Two-Step GaN Layer Growth for High-Voltage Lateral AlGaN/GaN HEMT ». Crystals 13, n^o 1 (3 janvier 2023) : 90. http://dx.doi.org/10.3390/cryst13010090.

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This paper presents reduced dislocation of the AlGaN/GaN heterostructure for high-voltage lateral high-electron-mobility transistor (HEMT) devices. AlGaN/GaN heterostructure was grown on sapphire substrate. Prior to the growth of the AlGaN layer, the GaN layer was grown via two-step growth. In the first step, the V/III ratio was applied at 1902 and then at 3046 in the second step. The FWHMs of the XRD (002) and (102) peaks of the GaN layer were around 205 arcsec ((002) peak) and 277 arcsec ((102) peak). Moreover, the surface of the GaN layer showed clear evidence of step flows, which resulted in the smooth surface of the layer as well as the overgrown of the AlGaN layer. Subsequently, the AlGaN/GaN heterostructure was fabricated into a lateral HEMT with wide gate-to-drain length (LGD). The device exhibited a clear working HEMT characteristic with high breakdown voltages up to 497 V. In comparison to many reported AlGaN/GaN HEMTs, no AlGaN interlayer was inserted in our AlGaN/GaN heterostructure. By improving the growth conditions for the two-step growth, the performance of AlGaN/GaN HEMTs could be improved further.

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Heikman, Sten, Stacia Keller, Scott Newman, Yuan Wu, Craig Moe, Brendan Moran, Mathew Schmidt, Umesh K. Mishra, James S. Speck et Steven P. DenBaars. « Epitaxial Lateral Overgrowth of High Al Composition AlGaN Alloys on Deep Grooved SiC Substrates ». Japanese Journal of Applied Physics 44, No. 13 (11 mars 2005) : L405—L407. http://dx.doi.org/10.1143/jjap.44.l405.

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Yoshioka, Hidekazu, et Yuta Yaegashi. « Robust stochastic control modeling of dam discharge to suppress overgrowth of downstream harmful algae ». Applied Stochastic Models in Business and Industry 34, n^o 3 (27 décembre 2017) : 338–54. http://dx.doi.org/10.1002/asmb.2301.

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Articles de revues sur le sujet « Algal overgrowth »

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