Three species of Sargassum are the P10st abundant intertidal macroalgae at Puerto Penasco, Sonora, Mexico. Sargassum johnstonii Setchell & Gardner, S. herporhizum Setchell & Gardner, and S. sinicola Setchell & Gardner var. camouii (Dawson) Norris & Yensen are zoned on emergent reef in low intertidal areas. Sargassum johnstonii occurs in a zone above dense stands of S. herporhizum, and scattered patches of S. 8inicola occur on the lowest emergent reef. Sargassum sinicola, the most abundant species, predominates in pools throughout the intertidal zone. In mid-intertidal pools the species show the same zonation with respect to water depth that they do on emergent reef. Ecological separation is clear, the species occurring in different vertical zones or different habitats (pools or emergent reef). At some sites where S. herporhizum is rare or absent, the upper limit of emergent S. sinicola plants shifts upward probably because of a combination of physical and biological factors. The three species in this highly seasonal region reach maximum size and canopy cover in early spring. All produce fertile receptacles in the spring and shed their branches and die back in summer. Surviving S. sinicola persist through the summer at larger sizes, recommence growth and produce a second crop of receptacles in the fall; the other two species grow but are not fertile until the following spring. The species differ in allocation of biomass to vegetative and sexual reproductive structures. Sargassum herporhizum invests a high proportion of its wet and dry biomass into extensively branched, rhizoidal holdfasts. The holdfasts of the other two species are smaller relative to their upper branches, and are not rhizoidal. Experimental clearings showed that S. herporhizum was the most effective at recovering continuous space after disturbance and also after normal summer dieback. Sargassum johnstonii and S. sinicola produce large volumes of sexual receptacles on buoyant branches, which have the potential for wide dispersal, whereas S. herporhizum produces a relatively small volume. A trade-off between short-range vegetative encroachment abilities and potential for long-range dispersal of sexual propagules may have occurred in the evolution of reproductive strategies of these Sargassum species.

Wang Hui. / "December 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 256-280) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Delisea pulchra is a red macroalga that produces furanones, a class of secondary metabolites that inhibit the growth and colonization of a range of micro- and macroorganisms. In bacteria, furanones specifically inhibit acyl homoserine lactone (AHL)- driven quorum sensing, which is known to regulate a variety of colonization and virulence traits. This thesis aims to unveil multiple aspects of the chemically mediated interactions between an alga and its bacterial flora. It was demonstrated that the quorum sensing genetic machinery of bacteria is laterally transferred, making traditional 16S rRNA gene based-diversity techniques poorly suited to identify quorum sensing species. Previous studies had shown that AHL-producing bacteria belonging to the roseobacter clade can be readily isolated from D. pulchra. Because of this, it was decided to use a roseobacter epiphytic isolate from this alga, Ruegeria strain R11, to conduct a series of colonization experiments on furanone free and furanone producing D. pulchra. Furanones were shown to inhibit Ruegeria strain R11's colonization and infection of D. pulchra. In addition, it was demonstrated that Ruegeria strain R11 has temperature-regulated virulence, similar to what is seen for the coral pathogen Vibrio shiloi. Rising ocean temperatures may explain bleached D. pulchra specimens recently observed at Bare Island, Australia. To assess whether quorum sensing is common within the roseobacter clade, cultured isolates from the Roseobacter, Ruegeria and Roseovarius genera were screened for AHL production. Half of the bacteria screened produced the quorum sensing signal molecules, AHLs. These AHLs were identified using an overlay of an AHL reporter strain in conjunction with thin layer chromatography (TLC). The prevalence of quorum sensing within the roseobacter clade, suggests that these species may occupy marine niches where cellular density is high (such as surface associated communities on substratum and marine eukaryotes). Diversity studies in marine microbial communities require appropriate molecular markers. The 16S rRNA gene is the most commonly used marker for molecular microbial ecology studies. However, it has several limitations and shortcomings, to which attention has been drawn here. The rpoB gene is an alternate ???housekeeping??? gene used in molecular microbial ecology. Therefore, the phylogenetic properties of these two genes were compared. At most taxonomic levels the 16S rRNA and rpoB genes offer similar phylogenetic resolution. However, the 16S rRNA gene is unable to resolve relationships between strains at the subspecies level. This lack of resolving power is shown here to be a consequence of intragenomic heterogeneity.

Delisea pulchra is a red macroalga that produces furanones, a class of secondary metabolites that inhibit the growth and colonization of a range of micro- and macroorganisms. In bacteria, furanones specifically inhibit acyl homoserine lactone (AHL)- driven quorum sensing, which is known to regulate a variety of colonization and virulence traits. This thesis aims to unveil multiple aspects of the chemically mediated interactions between an alga and its bacterial flora. It was demonstrated that the quorum sensing genetic machinery of bacteria is laterally transferred, making traditional 16S rRNA gene based-diversity techniques poorly suited to identify quorum sensing species. Previous studies had shown that AHL-producing bacteria belonging to the roseobacter clade can be readily isolated from D. pulchra. Because of this, it was decided to use a roseobacter epiphytic isolate from this alga, Ruegeria strain R11, to conduct a series of colonization experiments on furanone free and furanone producing D. pulchra. Furanones were shown to inhibit Ruegeria strain R11's colonization and infection of D. pulchra. In addition, it was demonstrated that Ruegeria strain R11 has temperature-regulated virulence, similar to what is seen for the coral pathogen Vibrio shiloi. Rising ocean temperatures may explain bleached D. pulchra specimens recently observed at Bare Island, Australia. To assess whether quorum sensing is common within the roseobacter clade, cultured isolates from the Roseobacter, Ruegeria and Roseovarius genera were screened for AHL production. Half of the bacteria screened produced the quorum sensing signal molecules, AHLs. These AHLs were identified using an overlay of an AHL reporter strain in conjunction with thin layer chromatography (TLC). The prevalence of quorum sensing within the roseobacter clade, suggests that these species may occupy marine niches where cellular density is high (such as surface associated communities on substratum and marine eukaryotes). Diversity studies in marine microbial communities require appropriate molecular markers. The 16S rRNA gene is the most commonly used marker for molecular microbial ecology studies. However, it has several limitations and shortcomings, to which attention has been drawn here. The rpoB gene is an alternate ???housekeeping??? gene used in molecular microbial ecology. Therefore, the phylogenetic properties of these two genes were compared. At most taxonomic levels the 16S rRNA and rpoB genes offer similar phylogenetic resolution. However, the 16S rRNA gene is unable to resolve relationships between strains at the subspecies level. This lack of resolving power is shown here to be a consequence of intragenomic heterogeneity.

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : [35]-41).

Thesis (M.A.)--Humboldt State University, 2009. / Includes bibliographical references (leaves xi-xiv, following leaf 48). Also available via Humboldt Digital Scholar.

Typescript Thesis (Ph. D.)--University of Oregon, 1983 Includes vita and abstract Bibliography: leaves 134-145 Another copy on microfilm is located in Archives

The aim of the present study was to determine the potential impact of intertidal grazers on the distribution of macro algae on the south coast of South Africa. Particular attention was paid to the large patellid limpet, Patella oculus, which is found thoughout the intertidal zone. Studies of gut contents revealed that Patella oculus was capable of ingesting not only the thallus of foliose (eg. Ulva spp.) and encrusting coralline macroalgae, but also spores and diatoms. The inclusion of these relatively small particles in the diet was surprising, as electron micrographs of the radula of P.oculus revealed that it is typically docoglossan in structure. Such radulae are thought to be poorly suited for collecting small food particles. Sand made up a significantly higher proportion of the gut contents than other particles at all shore heights, which suggests that P.oculus might be capable of excavating the rocky substratum, or of sweeping up sand, while searching for food. Analysis of the gut contents of other local herbivorous molluscs, was also carried out. These species included the winkles, Oxystele variegata and O.sinensis, and the small pulmonate limpets, Siphonaria concinna, S.capensis, and S.serrata. The guts of all species contained mainly spores and diatoms, although small fragments of Ulva sp. were found. The population structure of Patella oculus was investigated at two sites, Cannon Rocks and Old Woman's River. At Cannon Rocks, mean shell length of low-shore animals was significantly lower than that of both mid- and high-shore animals, while at Old Woman's River, no significant difference was found among shore heights. A regression equation for In (shell length) vs In (dry weight) was calculated, and based on length data, the biomass density (g dry mass.m⁻²) of P.oculus at Old Woman's River was estimated. Values ranged from 2.8 on the low- and midshore to 0.37 on the high-shore. A manipulative field experiment was used to determine the impact of mesograzers and macrograzers (such as Patella oculus) on the distribution of intertidal macro algae on the mid- and low-shore at Old Woman's River. Grazers were excluded using mesh cages (mesh size = 3mm), in two separate experiments, one in winter and the other in spring. Percentage cover of macroalgal species and sessile invertebrates was estimated at approximately 6 week intervals for up to 3 months. MANOV A showed that treatments did not significantly affect cover of macroalgae or barnacles during winter. However, towards the end of the spring experiment (midshore only) cover of barnacles and green foliose turfs did increase in those plots from which mesograzers and/or macro grazers were excluded. The failure of the statistical tests to detect significant differences at some time intervals may have been caused by high levels of variation among replicates. This suggests that factors other than grazing are of overriding importance in determining the distribution of local macroalgae. The existence of a possible symbiotic relationship between Patella oculus and the red foliose alga, Gelidium pristoides, was investigated. The availability of various substratum types, including rock, limpet shells, barnacles etc., and the proportion of the total cover of G.pristoides on each, was calculated. It was shown that a significantly higher proportion of the alga grew on limpet shells, although the availability of this substratum type was low. It is thought that the aggressive behaviour of P.oculus prevents all but juvenile Patella longicosta from grazing on its shell, thus providing a refuge from grazing for G.pristoides.

Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-03-04T16:25:51Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Roger Dissertação Mestrado 2014_ versão Final biblioteca_ Entregue_.pdf: 1359994 bytes, checksum: ce3bbcf3906e6cb72bdfea9a7b7e7d06 (MD5) / Made available in DSpace on 2016-03-04T16:25:51Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Roger Dissertação Mestrado 2014_ versão Final biblioteca_ Entregue_.pdf: 1359994 bytes, checksum: ce3bbcf3906e6cb72bdfea9a7b7e7d06 (MD5) Previous issue date: 2014-02-20 / CAPES / CNPq / FINEP / O gênero Shewanella é um representante da classe das Gammaproteobactérias, família Shewanellaceae, compondo um grupo de bactérias gram-negativas, móveis, baciliforme, oxidase positiva, comumente encontrada em ambiente marinho e isolada do trato digestivo de animais aquáticos. Devido a suas características vem sendo amplamente testado como probiótico na carcinicultura. Estes têm sido utilizados na aquicultura para o controle biológico, aumento da taxa de conversão alimentar e sistema imune dos camarões. Este estudo teve por objetivo identificar potenciais bactérias probióticas retiradas do hepatopâncreas e estômago do camarão cultivado em sistema heterotrófico, avaliar as relações filogenéticas das cepas com o gênero Shewanella e caracteriza-las através de análisesmorfológicas, bioquímicas, produção de biofilme e antibiograma. A partir do cultivo heterotrófico de Litopenaeus vannamei, foram selecionadas as cepasIPA-S.51, IPA-S.111 e IPA-S.252para identificação através do sequenciamento parcial do gene 16S rRNA e comparados ao GenBank – NCBI e RDP - Seqmatch. As cepas foram alinhadas a 45 espécies do gênero Shewanella e avaliadas filogeneticamente utilizando os métodos Neighbor-Joining, Máxima Verossimilhança e Inferência Bayesiana. Quanto àsanálises morfológicas foram avaliadas parâmetros de acordo com a similaridade a padrões estabelecidos. Os testes bioquímicos foram realizados com o auxílio dos kits BACTRAY I, BACTRAY II e BACTRAY III (Labroclin®), totalizando 30 testes bioquímicos. A avaliação da capacidade de formação de biofilme foi realizada segundo Christensen e colaboradores. No antibiograma as cepas bacterianas foram submetidas a 13 antibióticos distintos segundo à técnica de Kirby e Bauer, com três repetições. O sequenciamento das cepas revelou alta similaridade a espécie Shewanella algae, utilizando o GenBank e o RDP-seqmath. A Inferência Bayesiana apresentou maior aporte estatístico e fidelidade dentre os métodos analisados. A Shewanella upenei apresentou alta similaridade as cepas estudadas, assim como a S. algae. As análises filogenéticas não descartam a hipótese de novas espécies para IPA-S.51, IPA-S.111 e IPAS. 252. As cepas estudadas foram sensíveis aos antibióticos Ampicilina/Subactan, Ofloxacina e Tetraciclina. A caracterização fenotípica fortalece a hipótese de especiação para as cepas testadas. Portanto, a capacidade de formação de biofilme, adicionada ao alto potencial enzimático e antagonismo a patógenos, característico do gênero Shewanella, tornam estas cepas potenciais probióticos para carcinicultura. / The genus Shewanella is one representant of Gammoproteobacteria class, family Shewanellaceae, being part of gram-negative bacteria group, mobile, bacilliform, oxidasepositive, commonly found on marine environments and isolated from the digestive tract of aquatic animals. Due to its characteristics, some tests as probiotics are being carried out in carciniculture. They are being used on aquaculture for biological control, augmentations on feed conversion rates and immune system of shrimps. This study has as objective identify potentials probiotics bacteria found in the hepatopancreas and stomach of shrimps cultivated on heterotrophic based system, evaluating the strain phylogenetic relationships with Shewanella genus and characterizing them through morphological and biochemical analysis, biofilm production and antibiogram. The strains IPA-S.51, IPA-S.111 e IPA-S.252 were selected from the heterotrophic cultivation of Litopenaeus vannamei, identified through partial 16S rRNA sequencing and compared to GenBank – NCBI and RDP - Seqmatch.The strains were aligned to 45 species of Shewanella genus and phylogenetically evaluated using Neighbor-Joining,Maximum-Likelihood estimation and Bayesian Inference.Regarding the morphological analysis parameters were evaluated according with established standard similarities. The biochemical tests were conducted with the assistance of BACTRAY I, BACTRAY II and BACTRAY III (Labroclin®) kits, totalizing 30 biochemical tests.The Biofilm capacity evaluation was made according Christensen et al. Regarding the antibiogram, the bacterial strains had undergone 13 distinct antibiotics according Kirby and Bauer, with three repetitions. The strains sequencing showed high similarity to Shewanella algae species, using GenBank and RDP-seqmath.The Bayesian inference displayed higher statistic contribution e fidelity among the other methods.The Shewanella upenei showed high similarity to the strains in study also as Shewanella algae.The phylogenetic analysis does not exclude the hypothesis of IPA-S.51, IPA-S.111 e IPA-S.252 being new species.The strains studied were sensitives to the antibiotics Ampicillin/Sulbactam, Ofloxacin, Tetracyclin. The phenotypic characterization of the strains supports the hypothesis of speciation. Thus, the capacity of biofilm formation plus the high enzymatic potential and antagonism interactions to pathogens, characteristics found in the Shewanella genus, make these strains potential probiotics to carciniculture.

The present study was undertaken in the temporarily open/closed Mngazi and permanently open Mngazana estuaries, located on the subtropical east coast of South Africa. The results from this research will assist decision makers in the freshwater management of these systems. Intertidal and subtidal benthic chlorophyll a concentrations, water column chlorophyll a, nutrients and several physico-chemical parameters were measured between June 2002 and November 2003. The objective of this study was to determine if the presence of freshwater in the estuaries had an effect on the microalgae of both estuaries. Five sites were sampled in the Mngazi Estuary and 14 sites were sampled in the Mngazana Estuary. The average water column chlorophyll a was significantly higher (p<0.05) in the Mngazana Estuary (surface 7.8 ± 0.7 μg.l-1, bottom 6.4 ± 0.7 μg.l-1) compared to the Mngazi Estuary (surface 4.9 ± 1.2 μg.l-1, bottom 7.3 ± 1.5 μg.l-1). There was no evidence of an REI (river-estuary interface) zone in areas where the water column chlorophyll a concentrations were high even during open mouth conditions in the Mngazi Estuary. The REI is that area where salinity is less than 10 ppt and is characterized by high water column productivity. Even though both systems received some freshwater during the summer periods, this was not enough to stimulate phytoplankton growth and nutrient availability seems to be the major factor limiting phytoplankton in these systems. Flagellates and diatoms were the dominant phytoplankton groups in both estuaries during the entire sampling session. The relative abundance of the different phytoplankton groups did not show differences between sites. The relative abundance of flagellates was in most cases greater than 60% and diatoms made up the remainder. The average benthic chlorophyll a was higher in the Mngazana Estuary (intertidal 24 ± 6 μg.g-1 subtidal 15.2 ± 3 μg.g-1) compared to the Mngazi Estuary (intertidal 15.3 ± 4.3 μg.g-1 subtidal 5.4 ± 1.6 μg.g-1). Regions with high benthic chlorophyll a concentrations had high sediment organic content. Sediment organic content was higher in the Mngazana Estuary (1 percent - 8 percent) compared to the Mngazi Estuary (4 percent – 6.8 percent). The sites situated on the Main Channel had on average significantly higher (p<0.05) benthic chlorophyll a biomass compared to Creek 1 and Creek 2 in the Mngazana Estuary. Peaks in benthic chlorophyll a concentrations occurred in the intertidal sediments in Creek 1 (50.4 ± 13.4 μg.g-1) and Creek 2 (57.4 ± 1.4 μg.g-1) in the Mngazana Estuary, the peaks occurred in winter during a period of low freshwater inflow into the estuary. Microphytobenthic biomass measured in the Mngazi Estuary is among the lowest values reported in the literature for temporarily open/closed estuaries. Statistical 4 analysis showed no significant difference between benthic chlorophyll a during the different mouth conditions and sampling sessions in the Mngazi Estuary. Microalgal responses in the Mngazana Estuary were similar to those observed in other permanently open marine dominated estuaries. In the temporarily open/closed Mngazi Estuary microalgal characteristics were different to that of other temporarily open/closed estuaries probably because the estuary was only sampled in the open and semi-closed state.