1,728,533 research outputs found
Ecophysiological studies of three South African Ulva species from integrated seaweed
No full textIncludes bibliographical references (leaves 210-273).In South Africa, Ulva cultivation is of paramount importance to the marine aquaculture industry. Three local Ulva species (Ulva lactuca Linnaeus, Ulva rigida C. Agardh and Ulva capensis Areschoug) were selected for this research. The first two are currently cultivated on abalone farms for abalone feed and for use as bio-filters, and Ulva capensis was included because it is morphologically and biogeographically distinct from Ulva rigida in nature, despite the inability of molecular methods to separate them. Ulva rigida was collected at I & J farm and from nature at Kommetjie on the southwest of the Cape Peninsula, and U. lactuca was exclusively collected from I & J farm because it could not be found at sites where it had previously been recorded. Ulva capensis was exclusively collected from Kommetjie as this morphological species has not been recorded on abalone farms. The research also aimed to compare U. capensis with U. rigida on a variety of different measures, as molecular studies have suggested that they may represent a single polymorphic species
I’m so Ulva it: Using tufA DNA barcoding for identification and contextualization of Ulva species in Salish Sea
No full textUlva is a genus of green algae, rapidly becoming relevant due to potential uses in the blue
economy, in addition to potential biofuel and rare earth element uses. Ulva is characterized by its
rapid growth sometimes causing harmful blooms, making it increasingly important to study this
algae, particularly the understudied tubular forms. Ulva historically had been difficult to identify
based on morphology alone. This project identified Ulva species in the greater San Juan Islands
using DNA barcoding, comparing specimen morphological characteristics to what is typically
described for the species, as well as using DNA data to contextualize samples into larger clades.
From this, key morphological distinctions of identified species and potential distribution patterns
relating to environmental and geographic factors are elucidated. In total, 12 species of Ulva were
identified from 35 samples, with some samples matching traditional descriptions of named
species while some differing from what is expected based on morphology alone. The species
found included Ulva compressa, Ulva flexuosa, Ulva expansa, Ulva californica, Ulva fenestrata,
Ulva stenophylla, Ulva taeniata, Ulva intestinalis, Ulva prolifera, Ulva australis, Ulva linza, and
Ulva torta. In addition, 4 species of Blidingia were identified and treated as an outgroup. Not all
of these species however have been tied to a type specimen and more sequencing efforts are
needed to accurately quantify diversity of the San Juan region
Atividade antimicrobiana e controle da antracnose do feijoeiro comum (Phaseolus vulgaris L.) utilizando polissacarídeo e extratos de macroalga marinha Ulva fasciata
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina. Programa de Pós-Graduação em Biotecnologia.Compostos presentes em algas marinhas podem desempenhar importantes funções biológicas, entre elas: atividade antimicrobiana direta, influenciando as interações entre planta-patógeno ou ativando mecanismos de defesa das plantas tratadas. O polissacarídeo ulvana, os extratos solúvel e insolúvel em metanol, o extrato etanólico obtidos de Ulva fasciata e o polissacarídeo B obtido de Ulva sp. foram testados quanto a atividade antimicrobiana e o potencial desta macroalga marinha no controle da antracnose de feijoeiro comum, causada pelo fungo Colletotrichum lindemuthianum. Para a obtenção da ulvana, algas frescas foram autoclavadas com água destilada; a solução resultante foi filtrada e precipitada com etanol. O polissacarídeo foi identificado por RNM-1H e RNM-13C e I.V. como unidades repetitivas de ácido ulvanobiurônico-3-sulfato. Para a obtenção dos extratos metanólicos e do extrato etanólico, algas secas e moídas foram extraídas com metanol em sistema de soxhlet ou com etanol, respectivamente. A atividade antimicrobiana da ulvana e dos extratos metanólicos foi determinada pelo método de difusão em ágar frente a bactérias potencialmente patogênicas ao homem: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus, Micrococcus luteus, a levedura Candida albicans e bactérias fitopatogênicas: Xanthomonas campestris e Erwinia carotovora. A concentração inibitória mínima, através do método de microdiluição em caldo, foi determinada contra os fungos: C. lindemuthianum (fitopatogênico), Trichophyton mentagrophytes e Microsporum canis (dermatófitos). Além disto, o efeito da ulvana e dos extratos metanólicos foi avaliado, in vitro, nos testes de inibição de crescimento miceliano e inibição da germinação de conídios de C. lindemuthianum. In vivo, foi avaliado o efeito do extrato etanólico, extratos metanólicos, ulvana e polissacarídeo B na proteção de plantas de feijão comum (Phaseolus vulgaris L.) contra antracnose em casa-de-vegetação. Os resultados demonstraram que os extratos metanólicos inibiram o crescimento de bactérias Gram-negativas: P. aeruginosa, X. campestris e E. carotovora. Além disso, o extrato insolúvel (2 mg/ml) em metanol inibiu o crescimento de T. mentagrophytes e o extrato solúvel em metanol (1 e 2 mg/ml) inibiu significativamente (p<0,05) o crescimento miceliano de C. lindemuthianum. Por outro lado, nenhum dos extratos testados inibiu a germinação dos conídios deste fungo e a ulvana não apresentou nenhuma atividade in vitro contra os microrganismos testados. Nos experimentos in vivo, observou-se que o extrato etanólico (10 mg de alga seca/ml) e a ulvana (10 mg/ml) de U. fasciata apresentaram uma possível indução de resistência quando pulverizados três dias e quatro dias antes da inoculação do fungo, respectivamente
Meltdown in Algae Town: Implications of Warming Oceans on San Juan Island Ulva
No full textThe green alga, Ulva spp., represents a widely distributed and ecologically influential genus of
macroalgae that occurs in subtidal and intertidal habitats worldwide. A majority of Ulva spp.
have high nutrient uptake rates and rapid growth in nutrient-rich habitats, forming prolific algal
blooms known as green tides. The increasing frequency and severity of green tide events has
been attributed to coastal anthropogenic eutrophication, particularly as it relates to nitrogen.
Previous studies have indicated that high-temperature conditions may affect nitrogen metabolism
in Ulva, but further research is needed to understand the impacts and associations between
temperature and eutrophication on Ulva growth. The aim of this study was to gain insight into
the implications of climate change and consequent increasing ocean temperatures on the
proliferation of Ulva and potential for harmful green tide events. Effects of temperature on Ulva
were investigated by selecting one individual alga at each of three San Juan Island locations
(Eagle Cove, False Bay, and Friday Harbor Laboratories). A total of 9 Ulva discs (314 mm2)
were taken from each individual representative to place into three temperature treatments (12ºC-
14ºC, 17ºC-19ºC, and 23ºC-25ºC). Growth of discs was recorded three times during the
experimental period. No significant difference in temperature-dependent growth was found
based on site. However, the high temperature treatment was found to result in negative growth
independent of site. Future experiments should include a larger sample size, investigation of
additional abiotic factors and a longer experimental timeframe
Analysis of Nutrient Enrichment on Ulva Growth
No full textTo determine whether Ulva is nitrogen or phosphorus limited in San Juan Island
oceanographic conditions, samples were cut from a single individual utilizing a cork borer and
cultured in a lab environment. In addition to control conditions, five samples each were cultured
in four treatments of increased nitrate (5 μM, 25 μM, 50 μM, 100 μM) and four treatments of
increased phosphate (0.3125 μM, 1.5625 μM, 3.125 μM, 6.25 μM). Temperature of the
treatments were kept consistent with field conditions through usage of a sea table circulating
water, and light levels were kept constant (125 lx) through suspension of four fluorescent tube
lights above the seatable. Samples were cultured over a period of five days, and relative growth
of each treatment was measured utilizing a micrometer to determine average change in diameter
on the third and fifth day. Increased nitrate treatments had higher average growth than that of
increased phosphate, and both displayed significantly higher growth than that of the control.
Between the two treatments, statistical significance was determined for nitrate growth conditions
having higher average growth (p < 0.5). Treatments displayed moderate positive correlation
between increasing nitrate levels and growth (~0.66), with almost no correlation between
increasing phosphate levels and growth (~-.11). The data supports the hypothesis that Ulva
growth is nitrogen limited in San Juan Island oceanographic conditions
Estrutura da comunidade fitobêntica e respostas ecofisiológicas de Ulva lactuca e Sargassum cymosum frente a eventos de precipitação na Ilha de Santa Catarina, Florianópolis, SC, Brasil
Get PDFDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-Graduação em Biologia VegetalDesde décadas recentes, mudanças climáticas globais vêm causando drásticas mudanças biológicas ao longo do planeta, afetando uma ampla gama de organismos com distribuições geográficas diferentes, principalmente no que se diz respeito ao alcance e distribuição de espécies, composição e interação dentro da comunidade, e estrutura e dinâmica dos ecossistemas. Além disso, alterações nas interações tróficas, respostas fisiológicas e distribuição de produtores primários já têm sido possível observar nos últimos anos. Neste contexto, o trabalho em questão realiza uma análise comparativa da estrutura da comunidade fitobêntica, e das respostas ecofisiológicas de Ulva Lactuca Linnaeus e Sargassum cymosum C. Agardh de costões rochosos entremarés em dias consecutivos secos (DCS), e em momentos com precipitação extrema (EEP) no sul do Brasil. Para a caracterização da estrutura da comunidade foram feitas coletas qualitativas através de raspagem manual, e quantitativas através de fotoquadrats do material ficológico. Para a avaliação das respostas ecofisiológicas, foram feitas medições da fluorescência da clorofila a do fotossistema II, através de um fluorímetro de pulso com amplitude modulada (DIVING-PAM). A análise de variância da estrutura da comunidade indicou uma redução na riqueza, abundância e diversidade de Shannon após EEP em relação à DCS. Análises de porcentagem de similaridade também indicaram que macroalgas de morfotipos-funcionais calcárias articuladas, coriáceas e corticadas reduziram suas porcentagens de cobertura após EEP, entretanto, macroalgas foliáceas, representadas principalmente por Ulva lactuca, uma alga oportunista, e a porcentagem de costão rochoso com ausência de cobertura de macroalgas apresentaram um aumento após EEP. A análise de variância indicou diferenças significativas nos níveis de irradiação nos momentos avaliados e da irradiância de saturação (Ik) de Ulva lactuca e Sargassum cymosum. Além disso, os valores da eficiência fotossintética (a) e da taxa de transporte de elétrons (ETRmax) dessas espécies apresentaram-se maior após EEP. E, embora as duas espécies tenham respondido de maneira similar frente aos eventos avaliados, de modo geral, S. cymosum apresentou taxas fotossintetizantes menores que U. lactuca. Portanto, neste estudo, além das considerações feitas relacionadas à fotoproteção, zonação e fotoinibição, também são fornecidos dados que mostram a magnitude da perda da biodiversidade de algas e são discutidas as conseqüências diretas e indiretas nessas comunidades, devido o aumento na frequência e magnitude de extremos de precipitação, principalmente, ocasionadas pelas mudanças climáticas.Since recent decades, global climate change are causing dramatic biological changes over the planet, affecting a wide range of organisms with different geographical distributions, particularly as regards the scope and distribution of species composition and interaction within the community, and structure and dynamics of ecosystems. Furthermore, changes in trophic interactions, physiological responses and distribution of primary producers have already been possible to observe in recent years. In this context, the work in question performs a comparative analysis of phytobenthic community structure and ecophysiological responses of Ulva Lactuca Linnaeus and Sargassum cymosum C. Agardh from intertidal rocky shores after consecutive dry days (DCS), and after extreme precipitation (EEP) in southern Brazil. To characterize the community structure was collected through qualitative manual scraping, and quantitative means of photo-quadrats of phycological material. For the evaluation of ecophysiological responses, measurements were made of the chlorophyll fluorescence of photosystem II, using a fluorimeter pulse amplitude modulated (DIVING-PAM). The variance analysis of community structure showed a reduction in richness, abundance and diversity of Shannon for EEP in relation to the DCS. Analysis of percentage similarity also indicated that macroalgae- unctional morphotypes articulated calcareous, leathery and corticadas reduced their percentage of coverage after EEP, however, foliaceous macroalgae, mainly represented by Ulva lactuca, an opportunistic seaweed, and the percentage of rocky shore with no macroalgal cover showed an increase after EEP. Analysis of variance indicated significant differences in the levels of radiation measured in moments and saturation irradiance (Ik) of Ulva lactuca and Sargassum cymosum. Furthermore, the values of photosynthetic efficiency (á) and the rate of electron transport (ETRmax) of these species were higher after EEP. And, although these species have responded similarly front of events evaluated, in general S. cymosum photosynthetic rate made smaller than U. lactuca. Thus, in this study, in addition to the considerations made related to photoprotection, photoinhibition and zonation, are also provided data the magnitude of the loss of biodiversity of algae and discusses shows the direct and indirect consequences in these communities, because of increasing frequency and magnitude extremes of precipitation, mainly caused by climate change
The use of ULVA as a feed supplement in the development of an artificial diet and feeding regimes to produce export quality roe from the sea urchin Tripneustes gratilla (Linnaeus)
No full textIncludes bibliographical references.Tripneustes gratilla is a fast growing, shallow water echinoid, which occurs across the Indo-Pacific, with its south-western limit in warm, temperate waters of South Africa. The success of T. gratilla cultivation depends, in part, on the development of a high quality, costeffective, gonad-conditioning diet that can produce large, marketable quality gonads. The aim of this research was to determine whether Ulva supplementation would improve palatability, consumption and digestibility of an artificial feed administered to T. gratilla and optimise gonad production and quality. At an inclusion level of 20% (20U), Ulva was shown to significantly (p 0.05) smaller. Gonad production in the somatic growth phaseof the trial was higher for urchins fed with artificial diets (0U & 20U), but the reduced size of urchins in the 0U diets significantly reduced gonad mass. After the diets were changed from artificial feeds (0U & 20U) to fresh Ulva (FU) and vice versa (week 20), both gonad size and colour were affected, with artificial diets promoting gonad growth, while FU improved gonad colour. At the end of the study, all feeding regimes produced similar amounts of gonad, except for those individuals that were fed the 0U feed during the somatic growth phase (which were significantly (p > 0.05) smaller). Gonad colourationof all treatments at the end of the study was of marketable quality. From these results it is recommendedthat FU be fed inthe somatic growth phase, while the 20U artificial diet should be used to increase gonad size, and optimise gonad colour, in the gonad enhancement phase. Through the use of stable isotope mass spectrometry and IsoSource, a mixing and mass balance model, the relative contribution and importance of specific feed ingredientsto gonad production was determined. Ulva was shown to be an important isotopic source for gonad production, accounting for an average of 33% of the isotopic signal across all Ulvacontaining, diets at the end of the trial. The final section of work focused on efforts to manipulate the gametogenic cycle of T. gratilla, by altering daylength, to attempt to reduce the production of large amounts of gametes, which would decrease gonad value. Histology indicated that urchins exposed to a Short day (8:16 h) were significantly more advanced reproductively, with the majority of urchins in a mature or spent state compared to urchins exposed to a Long day (16:8 h), which were mostly premature. Nutritive phagocyte (NP) density within the gonads supported the findings from histology, as gonads from urchins exposed to a short day had significantly less NP's (21.58 ± 4.35%), compared to the Long day treatment (65.26 ± 3.09%). The results from this study suggest that urchins of this species exposed to Long days progress through gametogenesis more slowly than those exposed to Short days, which, appeared to mature more rapidly. These findings could allow for the production of a high quality product for longer periods of the year, without the onset of gonad maturation. The research in this thesis clearly shows that the use of the macroalga Ulva as a feed, or feed additive, to artificially formulated, high protein feeds can have a number of significant benefits in echinoculture. The use of the artificial feeds and feeding regimes developed in this work, along with the ability to manipulate daylenth to suspend gametogenisis, could greatly facilitate the success of the newly developing T. gratilla industry, both in South Africa and worldwide
"Chloroplast Genomes of the Green Tide Forming Alga Ulva compressa: Comparative Chloroplast Genomics in the Genus Ulva (Ulvophyceae, Chlorophyta)."
Get PDFTo understand the evolution of Ulva chloroplast genomes at intraspecific and interspecific levels, in this study, three complete chloroplast genomes of Ulva compressa Linnaeus were sequenced and compared with the available Ulva cpDNA data. Our comparative analyses unveiled many noticeable findings. First, genome size variations of Ulva cpDNAs at intraspecific and interspecific levels were mainly caused by differences in gain or loss of group I/II introns, integration of foreign DNA fragments, and content of non-coding intergenic spacer regions. Second, chloroplast genomes of U. compressa shared the same 100 conserved genes as other Ulva cpDNA, whereas Ulva flexuosa appears to be the only Ulva species with the minD gene retained in its cpDNA. Third, five types of group I introns, most of which carry a LAGLIDADG or GIYYIG homing endonuclease, and three of group II introns, usually encoding a reverse transcriptase/maturase, were detected at 26 insertion sites of 14 host genes in the 23 Ulva chloroplast genomes, and many intron insertion-sites have been found for the first time in Chlorophyta. Fourth, one degenerate group II intron previously ignored has been detected in the infA genes of all Ulva species, but not in the closest neighbor, Pseudoneochloris marina, and the other chlorophycean taxa, indicating that it should be the result of an independent invasion event that occurred in a common ancestor of Ulva species. Finally, the seven U. compressa cpDNAs represented a novel gene order which was different from that of other Ulva cpDNAs. The structure of Ulva chloroplast genomes is not conserved, but remarkably plastic, due to multiple rearrangement events
The Life History of Ulva reticulata Forsskål (Chlorophyceae, Ulvales) in Culture
Get PDFThe life history of Ulva reticulata, collected from Okinawa Island, southern Japan, was studied in laboratory culture. The gametes and zoospores were formed on the thalli from Okinawa. The zoospores are pyriform, with four flagella, one eye-spot and showing positive phototaxis. They began to germinate and developed into male and female gametophytes. The gametes are elongated pyriform, with two flagella, one eye-spot and showing strong positive phototaxis. The gametes from different sex conjugated anisogamously. The zygotes immediately germinated and developed into sporophyets forming zoospores. Both male and female gametes also germinated parthenogenetically and then grew up to male and female plants respectively. The chromsome number of this plant was nine in gametophytes, and eighteen in sporophytes. From the above results, Ulva reticulata is a diplo-haplont having the alternation of isomorphic generations
Long-term trend of Ulva prolifera blooms in the western Yellow Sea
Get PDFBlooms of the green macroalga Ulva prolifera in the western Yellow Sea occurred every year since 2008, and they have been reported and studied extensively using a variety of means including remote sensing. However, to date, long-term bloom patterns have not been reported except for a few case studies showing examples in different years. Here, using MODIS observations and an objective method to perform statistical analysis, mean Ulva coverage in the western Yellow Sea has been derived and analyzed between 2007 and 2015 at both monthly and annual scales. On annual scale, mean Ulva coverage decreased after 2008, but increased rapidly after 2012 from 8 km(2) in 2012 to 116 km2 in 2015 (the largest ever reported in history for this region). In the month of June the mean coverage increased from 18 km2 in 2012 to 363 km2 in 2015. Other than 2009 and 2010, the month of June showed maximum Ulva coverage in every year. These coverage estimates are significantly lower than previously reported values as they represent "pure" algae coverage after taking into account of partial pixel coverage. Several environmental factors were examined in an attempt to determine the reasons behind such long-term changes, yet the results are inconclusive, suggesting a strong necessity of further coordinated and multi-disciplinary researches. (C) 2016 Elsevier B.V. All rights reserved
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