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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Regional and local patterns in kelp morphology and benthic assemblages

Fowler-Walker, Meegan J. January 2005 (has links)
Most ecologists work at scales where complexity is greatest ( i.e. local ), and it is not surprising, therefore, that we tend to be captivated by the description and explanation of local variation whilst being pessimistic about the existence of broader patterns. Using a character ( kelp morphology ) known for its local and unaccounted variation, the morphology of the canopy - forming algae Ecklonia radiata ( Phaeophyta ) was quantified across > 5000 km of temperate Australian coastline, ( i ) between different configurations of algal stand ( i.e. monospecific vs mixed - species stands ) and ( ii ) across multiple spatial scales. A key result was that despite variation at local scales ( km ), differences between stands became increasingly clear at broad scales ( 1000 ' s km ), which supports the idea that large - scale patterns can emerge from apparent stochasticity at small scales. Within each stand, regional scale differences in morphological characters were evident ( i.e. Western Australia = South Australia ≠ Eastern Australia ). These characters correlated with geographic and environmental variables to indicate that the majority of morphological variation across temperate Australia was accounted for by longitude, wave exposure, water temperature and plant density. Morphological differences associated with environmental factors may reflect a plastic response to the local environment, or alternatively may reflect genetically fixed traits ( i.e. ecotypes ). An independent test of morphological variation associated with wave exposure environments, using a reciprocal transplant experiment, revealed that morphological plasticity was the mechanism enabling E. radiata to adopt different morphologies between exposure environments. The presence of kelp canopies has strong spatial relationships with organisms growing underneath them, and variation in the morphology of these canopies may facilitate distinct assemblages within the understorey habitat. Variation in the morphology of E. radiata was found to be associated with the structure of understorey assemblages, over broad spatial scales. This canopy - understorey association revealed two ' types ' of kelp forest ; one characteristic of Western and Southern Australia and the other of Eastern Australia. Patterns of canopy - benthos association have mostly been done on horizontal surfaces and experimental tests showed that such patterns on horizontal surfaces were not representative of vertical surfaces, which enables us to recognize the conditions for which we can reliably anticipate the structure of benthic organisms, thereby improving the predictive power of models that account for widespread patterns in subtidal heterogeneity. In conclusion, this thesis suggests that there are fundamental differences between the ecology of kelp forests at local scales ( i.e. between types of stand ) and at regional scales ( i.e. between the south and east coast of temperate Australia ), reflecting differences in kelp morphology that may be caused by environmental conditions ( e.g. exposure ) and may influence associated taxa ( e.g. understorey ). Consideration of such local - scale variation ( specificity ) when testing for the existence of broad - scale phenomena ( generality ) not only strengthens our understanding of the ecology of subtidal forests, but will also improve the predictive power of further research in this system. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.
72

Seasonal variations in the chemical composition of selected Hong Kong seaweeds.

January 1997 (has links)
by Chan Ching Ching Jenny. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 118-127). / Acknowledgments --- p.i / Abstract --- p.ii / List of figures --- p.iv / List of tables --- p.vii / List of abbreviations --- p.viii / Chapter Chapter 1. --- Introduction / Chapter 1.1 --- Consumption and classification of seaweeds --- p.1 / Chapter 1.2 --- Present uses of seaweeds --- p.4 / Chapter 1.2.1 --- The chemical composition of seaweeds --- p.4 / Chapter 1.2.2 --- Industrial uses - phycocolloids / Chapter 1.2.2.1 --- Alginate --- p.7 / Chapter 1.2.2.2 --- Carrageenan --- p.9 / Chapter 1.2.2.3 --- Agar --- p.12 / Chapter 1.3 --- Seasonal variations studies --- p.14 / Chapter 1.4 --- Seaweeds in Hong Kong --- p.16 / Chapter 1.5 --- Seaweeds selected for study / Chapter 1.5.1 --- Sargassum species / Chapter 1.5.1.1 --- Uses of Sargassum --- p.16 / Chapter 1.5.1.2 --- Seasonal variations of Sargassum --- p.17 / Chapter 1.5.2 --- Hypnea species --- p.19 / Chapter 1.6 --- Drying methods used in seaweed studies and industrial processing --- p.20 / Chapter 1.7 --- Significance of the present study --- p.22 / Chapter Chapter 2. --- Materials and methods / Chapter 2.1 --- "Location, seaweed collection, and environmental parameters" --- p.24 / Chapter 2.2 --- Sample preparation --- p.24 / Chapter 2.3 --- Chemical composition analysis / Chapter 2.3.1 --- Protein --- p.26 / Chapter 2.3.2 --- Amino acids --- p.28 / Chapter 2.3.3 --- Dietary fiber --- p.29 / Chapter 2.3.4 --- Sugar --- p.30 / Chapter 2.3.5 --- Ash --- p.31 / Chapter 2.3.6 --- Mineral elements --- p.32 / Chapter 2.3.7 --- Vitamin C --- p.32 / Chapter 2.3.8 --- Moisture --- p.33 / Chapter 2.4 --- Characterization of alginate from brown seaweed Sargassum hemiphyllum / Chapter 2.4.1 --- Alginate extraction --- p.33 / Chapter 2.4.2 --- Uronic acid block composition determination --- p.34 / Chapter 2.4.2.1 --- M/G ratio determination --- p.35 / Chapter 2.4.2.2 --- Phenol-sulfuric acid method for determination of sugar --- p.35 / Chapter 2.5 --- Characterization of carrageenan from red seaweed Hypnea charoides / Chapter 2.5.1 --- Carrageenan extraction --- p.35 / Chapter 2.5.2 --- Chemical analysis of carrageenan - sulfate content --- p.36 / Chapter 2.5.3 --- Physical analysis of carrageenan / Chapter 2.5.3.1 --- Gelling temperature --- p.37 / Chapter 2.5.3.2 --- Gelling concentration --- p.37 / Chapter 2.6 --- Data Analysis --- p.38 / Chapter Chapter 3. --- "Comparative studies on the effect of sun-drying, oven-drying, and freeze- drying methods on the chemical composition of brown seaweed Sargassum hemiphyllum" / Chapter 3.1 --- Results and discussion / Chapter 3.1.1 --- Color and appearance --- p.39 / Chapter 3.1.2 --- Chemical composition / Chapter 3.1.2.1 --- "Protein, dietary fiber, ash, and moisture" --- p.39 / Chapter 3.1.2.2 --- Amino acids --- p.42 / Chapter 3.1.2.3 --- Mineral elements --- p.44 / Chapter 3.1.2.4 --- Vitamin C --- p.46 / Chapter 3.1.3 --- Characterization of alginate / Chapter 3.1.3.1 --- Extraction of alginate --- p.46 / Chapter 3.1.3.2 --- Uronic acid block composition and M/G ratio --- p.48 / Chapter 3.2 --- Summary --- p.50 / Chapter Chapter 4. --- Seasonal variations in the chemical composition of brown seaweed Sargassum hemiphyllum / Chapter 4.1 --- Results and discussion / Chapter 4.1.1 --- Environmental parameters --- p.53 / Chapter 4.1.2 --- Morphology --- p.58 / Chapter 4.1.3 --- Chemical composition / Chapter 4.1.3.1 --- Protein and amino acids --- p.60 / Chapter 4.1.3.2 --- Dietary fiber and polysaccharide sugars --- p.64 / Chapter 4.1.3.3 --- Ash and mineral elements --- p.69 / Chapter 4.1.3.4 --- Vitamin C --- p.76 / Chapter 4.1.3.5 --- Water and moisture --- p.78 / Chapter 4.1.4 --- Characterization of phycocolloid - alginate / Chapter 4.1.4.1 --- Alginate extraction --- p.78 / Chapter 4.1.4.2 --- Uronic acid block composition and M/G ratio --- p.79 / Chapter Chapter 5. --- Seasonal variations in the chemical composition of red seaweed Hypnea charoides / Chapter 5.1 --- Results and discussion / Chapter 5.1.1 --- Environmental parameters --- p.82 / Chapter 5.1.2 --- Color and appearance --- p.86 / Chapter 5.1.3 --- Chemical composition / Chapter 5.1.3.1 --- Protein and amino acids --- p.88 / Chapter 5.1.3.2 --- Dietary fiber and polysaccharide sugars --- p.93 / Chapter 5.1.3.3 --- Ash and mineral elements --- p.97 / Chapter 5.1.3.4 --- Vitamin C --- p.104 / Chapter 5.1.3.5 --- Water and moisture --- p.104 / Chapter 5.1.4 --- Characterization of phycocolloid - carrageenan / Chapter 5.1.4.1 --- Carrageenan extraction --- p.106 / Chapter 5.1.4.2 --- Chemical characteristic of carrageenan - sulfate content --- p.109 / Chapter 5.1.4.3 --- Physical characteristics of carrageenan / Chapter 5.1.4.3.1 --- Gelling temperature --- p.110 / Chapter 5.1.4.3.2 --- Gelling concentration --- p.110 / Chapter Chapter 6. --- Conclusion --- p.113 / Chapter 6.1 --- Development perspectives of seaweeds --- p.116 / Chapter Chapter 7. --- References --- p.118 / Chapter Chapter 8. --- Appendixes --- p.128
73

Harmful algal blooms in selected Hong Kong coastal waters

Yang, Zhenbo., 揚振波. January 2000 (has links)
published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy
74

Genetic diversity in Emiliania huxleyi

Barker, Gary L. A. January 1995 (has links)
No description available.
75

THE EVOLUTION OF MARINE ALGAL - INVERTEBRATE SYMBIOSIS WITH SPECIAL REFERENCE TO THE PROCHLORON - DIDEMNUM SYMBIOSIS.

Michaels, Anthony Francis. January 1983 (has links)
No description available.
76

The formation of halocarbons by marine organisms

Connolly, Helen January 1990 (has links)
No description available.
77

Comparative ecophysiology of bloom-forming macroalgae in the Indian River Lagoon, Florida: Ulva lactuca (Chlorophyta), Hypnea musciformis, and Gracilaria tikvahiae (Rhodophyta)

Unknown Date (has links)
Macroalgal blooms are responses to nutrient enrichment in shallow seagrass ecosystems like the Indian River Lagoon (IRL), Florida. Little is known about nitrogen (N) and phosphorus (P) limitation or the importance of morphological/physiological characteristics of bloom-forming macroalgae (Ulva lactuca, Hypnea musciformis, and Gracilaria tikvahiae) in the IRL. We hypothesized: 1) all species would proliferate in nutrient-rich Titusville, 2) opportunistic U. lactuca would dominate, 3) Rapid Light Curves (RLCs) would assess nutrient status, and 4) nutrient concentrations would regulate growth more than N:P ratios. Field studies showed rapid biomass doubling times of 2 days (U. lactuca; November 2012) in urbanized Titusville. RLCs in a guano-enriched island off Big Pine Key (BPK) and Titusville (Ulva spp.) were similar due to P-saturation. Laboratory studies showed three-fold higher RLCs and two-fold faster growth at high nutrient concentrations of N and P. Reductions of both N and P will be required to moderate future blooms. / by Lisa N.A. Vlaming. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.
78

Effects of sedimentation on the structure of a phaeophycean dominated macroalgal community.

Turner, David John January 2004 (has links)
Macroalgae are abundant on shallow temperate reef environments, often forming complex communities that comprise several strata. In southern Australia, these assemblages are dominated by large canopy forming taxa from the Orders Laminariales and Fucales. The presence of subtidal fucoid macroalgae differentiates these communities from that elsewhere, and emphasises the need for local studies rather than relying on generalisations made elsewhere. Like most natural systems, temperate reefs are often threatened by human activity with degradation reported from many locations in close proximity to urban settlements. The work presented in this thesis involves an examination of the temporal and spatial variability in the structure of macroalgal communities from reefs along the Adelaide (South Australia) metropolitan coast. The work looked specifically at the effects of a dispersed sediment plume, resulting from the 1997 beach sand-replenishment dredging program, on shallow sub-tidal reef systems. An examination of the structure of canopy forming phaeophycean macroalgae in Gulf St Vincent (South Australia), noted large amounts of both spatial and temporal heterogeneity. Notwithstanding, this variation was not random, but demonstrated considerable structure that could be linked to a number of important underlying processes. In particular, macroalgal assemblages appeared as a mosaic of patches, each of which comprised a high-density state clearly dominated by a single genus (Cystophora, Sargassum, or Ecklonia), or alternatively a lower density mixed assemblage (Variable Low Abundance, VLA). Macroalgal community structure appeared to be driven by biotic interactions at small scales (metres), such that patches comprised of different species of algae in high density states rarely abutted one another. Instead, VLA assemblages frequently formed a buffer being situated between these mono generic patches. In terms of successional processes, the high-density states appeared to be relatively stable whereas the VLA state, at least in some systems, was transitory. This finding was supported by the absence of intermediary high- density states (e.g. a mix of Cystophora and Ecklonia) implying that state changes must occur via the VLA state following some form of disturbance. Larger scale patterns appeared to be driven by environmental variation, with factors such as wave exposure influencing habitat suitability for individual species and thereby affecting community composition. These phenomena were examined in terms of life history strategies that tend to promote stability, and which are common in late successional taxa. The importance of properties enhancing stability and the role of disturbance was investigated experimentally using a dispersed sediment plume, which entirely engulfed two reefs, as a pulse impact. This disturbance was of particular relevance given that degradation of macroalgal communities in close proximity to the City of Adelaide has been, at least in part, attributed to the effects of elevated levels of sediment. Follow up surveys revealed that the sedimentation from the plume had primarily affected newly recruiting individuals, with few juveniles surviving to one year of age. Over the following few years, the effect of this recruitment failure cascaded into the adult stand. In broader terms, unfavourable climatic conditions prior to the start of the study, including a particularly severe El Nino event, had a widespread effect on local assemblages, causing high levels of both adult and juvenile mortality. As such, at the commencement of the study, macroalgal communities across the study area were in the process of recovery. This was observed at control sites over the duration of the study. In contrast, recruitment failure at the sediment-affected sites retarded the recovery process, exacerbating the problems associated with prior unfavourable climatic events and leaving them in a degraded state. This study demonstrated that macroalgal assemblages are equipped (under natural conditions) to handle 'normal' environmental fluctuations (such as inter-annual variability). However, the additional stress associated with certain anthropogenic impacts has the potential to push them over the limit, causing degradation. The loss of canopy macroalgae reduces the structural complexity of the system, leading to a concomitant reduction in their ability to recover. As such, these findings are of particular relevance to those charged with the responsibility for managing near-shore marine environments. The plume was created accidentally during a dredging operation for beach sand replenishment of Adelaide's eroding shoreline. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2004.
79

Novel oxylipins and other bioactive metabolites from marine algae

Nagle, Dale George 07 December 1994 (has links)
I have participated in a drug discovery program designed to screen marine algae for inhibitors of cancer-related enzymes, antitumor compounds, antiinflammatory substances, and other agents of potential pharmaceutical utility. Over 1,500 lipid and aqueous extracts of marine plants and animals were surveyed for biomedical potential. Assays designed to screen extracts for new types of marine toxins have served to guide the isolation and identification of biologically active compounds. Extracts of the Oregon marine alga Constantinea simplex were found to contain a mixture of constanolactones, and lactonized cyclopropyl-containing oxylipin metabolites that logically derive from arachidonic and eicosapentaenoic acids. Spectroscopic analysis and chiroptical measurements of the natural products and various synthetically produced derivatives afforded the structures of seven structurally related compounds. Nakienones A-C and nakitriol, a series of reactive cytotoxic metabolites, were isolated from dead and necrotic branches of stony coral (Acropora sp.) which were completely covered with a gray-black mat of cyanobacteria (Synechocystis sp.). Their structures were determined spectroscopically by interpretation of 2D-NMR experiments, including heteronuclear multiple-bond coherence spectroscopy (HMBC) and 2-D nuclear Overhauser exchange spectroscopy (NOESY), and by comparison with model compounds. Bioassay-guided fractionation of the organic extract of a Curacao Lyngbya majuscula organic extract led to the isolation of an extremely potent brine shrimp toxin with antiproliferative activity. The structure of this new thiazoline ring-containing lipid, curacin A, was deduced from spectroscopic information and comparison of products obtained from chemical degradation of the natural product with the same substances prepared by synthesis. Curacin A is an antimitotic agent that inhibits microtubule assembly and the binding of colchicine to tubulin. In addition to curacin A, a potent new ichthyotoxic depsipeptide (antillatoxin), a new malyngamide derivative, and an unusual molluscicidal compound have been isolated from this alga. / Graduation date: 1995
80

Biosynthesis and enzymology of conjugated polyenoic fatty acid production in macrophytic marine algae

Wise, Mitchell L. 11 January 1995 (has links)
Graduation date: 1995

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