Crustose coralline algae (CCA) are important reef stabilizers and their susceptibility to anthropogenic climate change and ocean acidification (OA) is of concern. Ocean acidification effects on benthic algal communities were determined by the response of CCA, fleshy macroalgae and microalgae to the interaction of pCO2 and light. I examined if elevated pCO2 and light influences CCA dominance by assessing their growth, recruitment and calcification. Elevated pCO2 under natural reef diurnal CO2 cycles did not significantly affect CCA percent cover, calcification rates or survival of adult CCA lobes. No significant community pCO2 effects were observed, rather light controlled dominance. The percent cover of microalgae increased in highlight, while CCA increased in the shade. My results indicate that algal response to irradiance is a more significant driver of reef benthic algal change than pCO2 levels predicted for 2100; however, this conclusion should be corroborated in longer-term and in field experiments. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

by Wong Ka Hing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references. / Abstracts in English and Chinese. / Dedication --- p.i / Thesis committee --- p.ii / Acknowledgements --- p.iii / Abstract --- p.iv / Abstract (Chinese version) --- p.vi / Table of contents --- p.viii / List of tables --- p.xv / List of figures --- p.xviii / List of abbreviation --- p.xix / Chapter Chapter one: --- General introduction / Chapter 1.1. --- Definition --- p.1 / Chapter 1.2. --- Classification --- p.2 / Chapter 1.3. --- Potential food use of seaweeds --- p.7 / Chapter 1.4. --- Hong Kong seaweeds --- p.10 / Chapter 1.5. --- Sargassum species --- p.12 / Chapter 1.6. --- Hypnea species --- p.13 / Chapter 1.7. --- Ulva species --- p.14 / Chapter 1.8. --- Design of research project --- p.15 / Chapter Chapter two: --- "Effect of diflerent drying methods on proximate composition, amino acid profile and some physico-chemical properties of brown seaweeds, Sargassum hemiphyllum, Sargassum henslowianum and Sargassum patens" / Chapter 2.1. --- Introduction --- p.20 / Chapter 2.2. --- Materials and methods --- p.23 / Chapter 2.2.1. --- Sample preparation --- p.23 / Chapter 2.2.2. --- Proximate analysis --- p.26 / Chapter 2.2.2.1. --- Crude protein content --- p.26 / Chapter 2.2.2.2. --- Ash content --- p.26 / Chapter 2.2.2.3. --- Total dietary fiber (TDF) content --- p.27 / Chapter 2.2.2.4. --- Crude lipid content --- p.28 / Chapter 2.2.2.5. --- Carbohydrate content --- p.29 / Chapter 2.2.2.6. --- Moisture analysis --- p.29 / Chapter 2.2.3. --- Amino acid analysis --- p.30 / Chapter 2.2.3.1. --- "Amino acids excluding cystine, methionine and tryptophan" --- p.30 / Chapter 2.2.3.2. --- Cystine and methionine --- p.31 / Chapter 2.2.4. --- Physico-chemical properties --- p.32 / Chapter 2.2.4.1 --- Swelling capacity (SWC) --- p.32 / Chapter 2.2.4.2. --- Water holding capacity (WHC) --- p.32 / Chapter 2.2.4.3. --- Oil holding capacity (OHC) --- p.33 / Chapter 2.2.5. --- Statistical analysis --- p.34 / Chapter 2.3. --- Results and discussion --- p.34 / Chapter 2.3.1. --- Proximate composition --- p.34 / Chapter 2.3.2. --- Amino acid composition --- p.39 / Chapter 2.3.3. --- Physico-chemical properties --- p.42 / Chapter 2.3.4. --- Conclusions --- p.46 / Chapter Chapter three: --- "Effect of different methods on protein extarctability, in vitro protein digestibility and amino acid profile of seaweed protein concentrates isolated from brown seaweeds, Sargassum hemiphyllum, Sargassum henslowianum and sargassum patens" / Chapter 3.1. --- Introduction --- p.48 / Chapter 3.2. --- Materials and methods --- p.51 / Chapter 3.2.1. --- Sample preparation --- p.51 / Chapter 3.2.2. --- Extraction of seaweed protein concentrates --- p.51 / Chapter 3.2.3. --- Precipitation of seaweed protein concentrates --- p.52 / Chapter 3.2.4. --- Crude protein content analysis --- p.53 / Chapter 3.2.5. --- Extraction of total phenolic compounds --- p.53 / Chapter 3.2.6. --- Determination of total phenolic compounds --- p.54 / Chapter 3.2.7. --- In vitro protein digestibility --- p.55 / Chapter 3.2.8. --- Amino acid analysis --- p.56 / Chapter 3.2.9. --- Statistical analysis --- p.56 / Chapter 3.3. --- Results and discussion --- p.56 / Chapter 3.3.1. --- Effect of oven- or freeze-drying on protein extractability from seaweeds --- p.57 / Chapter 3.3.1.1. --- Total crude protein and total phenolic content in seaweeds --- p.57 / Chapter 3.3.1.2. --- "%Nitrogen, %protein, sample dry weight, amount of protein extracted and %yield of PCs" --- p.60 / Chapter 3.3.2. --- Effect of oven- and freeze-drying on protein quality of seaweed PCs --- p.62 / Chapter 3.3.2.1. --- Total phenolic content and in vitro protein digestibility of seaweed PCs --- p.62 / Chapter 3.3.2.2. --- Amino acid composition --- p.64 / Chapter 3.3.3. --- Conclusions --- p.67 / Chapter Chapter four: --- "Proximate composition, amino acid profile and some physico- chemical properties of some red (Hypnea charoides and Hypnea japonica) and green seaweeds (Ulva lactuca)" / Chapter 4.1. --- Introduction --- p.68 / Chapter 4.2. --- Materials and methods --- p.71 / Chapter 4.2.1. --- L Sample preparation --- p.71 / Chapter 4.2.2. --- Proximate analysis --- p.71 / Chapter 4.2.3. --- Amino acid profile --- p.73 / Chapter 4.2.4. --- Physico-chemical properties --- p.73 / Chapter 4.2.5. --- Statistical analysis --- p.74 / Chapter 4.3. --- Results and discussion --- p.74 / Chapter 4.3.1. --- Proximate composition --- p.74 / Chapter 4.3.2. --- Amino acid composition --- p.78 / Chapter 4.3.3. --- Physico-chemical properties --- p.81 / Chapter 4.3.4. --- Conclusions --- p.86 / Chapter Chapter five: --- In vitro protein digestibility and amino acid profile of seaweed protein concentrates isolated from some red (Hypnea charoides and Hypnea japonica) and green seaweeds (Ulva lactuca) / Chapter 5.1. --- Introduction --- p.88 / Chapter 5.2. --- Materials and methods --- p.89 / Chapter 5.2.1. --- Sample preparation --- p.89 / Chapter 5.2.2. --- Extraction and precipitation of seaweed PCs --- p.90 / Chapter 5.2.3. --- Crude protein analysis --- p.90 / Chapter 5.2.4. --- Extraction and determination of total phenolic contents --- p.90 / Chapter 5.2.5. --- In vitro protein digestibility --- p.91 / Chapter 5.2.6. --- Amino acid analysis --- p.92 / Chapter 5.2.7. --- Statistical analysis --- p.92 / Chapter 5.3. --- Results and discussion --- p.93 / Chapter 5.3.1. --- Protein extractability --- p.93 / Chapter 5.3.1.1. --- Crude protein and total phenolic contentin seaweeds --- p.93 / Chapter 5.3.1.2. --- "%Nitrogen, %protein, sample dry weight, amount of protein extracted and %yield of PCs" --- p.95 / Chapter 5.3.2. --- Protein quality --- p.97 / Chapter 5.3.2.1. --- Total phenolic content and in vitro protein digestibility of seaweed PCs --- p.97 / Chapter 5.3.2.2. --- Amino acid composition --- p.99 / Chapter 5.3.3. --- Conclusions --- p.103 / Chapter Chapter six: --- Biological evaluation on protein quality of seaweed protein concentrates isolated from Hypnea charoides and Hypnea japonica / Chapter 6.1. --- Introduction --- p.104 / Chapter 6.2. --- Materials and methods --- p.114 / Chapter 6.2.1. --- Sample preparation --- p.114 / Chapter 6.2.2. --- Extraction and precipitation of seaweed protein concentrates --- p.114 / Chapter 6.2.3. --- Diet preparation --- p.115 / Chapter 6.2.4. --- Rat bioassay --- p.117 / Chapter 6.2.5. --- Biological indices --- p.118 / Chapter 6.2.6. --- Statistical analysis --- p.119 / Chapter 6.3. --- Results and discussion --- p.119 / Chapter 6.3.1. --- Protein quality of seaweed PCs --- p.119 / Chapter 6.3.2. --- Weight of major organs --- p.126 / Chapter 6.3.3. --- Conclusions --- p.129 / Chapter Chapter seven: --- Functional properties of protein concentrates isolated from Hypnea charoides and Hypnea japonica / Chapter 7.1. --- Introduction --- p.130 / Chapter 7.2. --- Materials and methods --- p.136 / Chapter 7.2.1. --- Sample preparation --- p.136 / Chapter 7.2.2. --- Preparation of protein concentrates --- p.137 / Chapter 7.2.3. --- Nitrogen solubility --- p.137 / Chapter 7.2.4. --- Water and oil holding capacity --- p.138 / Chapter 7.2.5. --- Viscosity --- p.139 / Chapter 7.2.6. --- Emulsifying activities and emulsion stability --- p.140 / Chapter 7.2.7. --- Foam capacity and foam stability --- p.141 / Chapter 7.2.8. --- Statistical analysis --- p.142 / Chapter 7.3. --- Results and discussion --- p.142 / Chapter 7.3.1. --- Nitrogen solubility --- p.142 / Chapter 7.3.2 --- Wafer and oil holding capacity --- p.145 / Chapter 7.3.3. --- Viscosity --- p.147 / Chapter 7.3.4 --- Emulsifying activities and emulsion stability --- p.149 / Chapter 7.3.5. --- Foam capacity and foam stability --- p.153 / Chapter 7.3.6. --- Conclusions --- p.157 / Chapter Chapter 8: --- Conclusions --- p.158 / References --- p.160 / Appendix --- p.195 / Related publications --- p.202

Field data from CO2 vents, a current model of future ocean acidification conditions, show a positive correlation between elevated seawater pCO2 and fleshy macroalgal abundance, as well as a negative correlation between elevated seawater pCO2 and calcareous macroalgal abundance on coral reefs. One underlying physiological mechanism for increases of fleshy macroalgae species in response to greater pCO2 could be an increase in their photosynthesis. Furthermore, inorganic carbon use mechanisms, irradiance and depth may influence species-specific responses to ocean acidification. Therefore, this thesis aimed to discern carbon use strategies and photosynthetic responses to elevated pCO2 of dominant tropical fleshy and calcareous macroalgae. All species studied were able to utilize HCO3 - for photosynthesis. 33% of calcifying macroalgae and 80% of fleshy macroalgae had increased photosynthetic rates in response to lower pH. Thus, future conditions of OA may perpetuate or exacerbate the abundance of fleshy seaweeds at the expense of calcareous species. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

No periodic patterns of temporal variations in the metal levels in U. lactuca or in other seven common seaweed species from Ping Chau were observed from 1999 to 2000. Cu levels were generally negatively correlated with other metals in seaweeds. / Spore production of U. lactuca was significantly reduced by the elevation of copper and nickel levels in the seaweed samples. The reproductive frequency of U. lactuca generally increased from January and February to the maxima in March and April. Copper, nickel and nitrate levels showed significant negative correlations with these reproductive frequencies. / The metal abundance in 24 seaweeds showed the following trend: Fe > Mn, Zn > Cu, Ni, Pb, Cr > Cd. U. lactuca and Padina australis showed relatively high mean and large range values of metal levels. Principal component analysis summarized the overall metal loadings in these 24 seaweed species. The variations in Pb, Fe, Mn and Cr levels in the seaweeds varied greatly. / There were significant spatial variations of different metal levels in the extensive study of U. lactuca from various intertidal waters in Hong Kong from 1999 to 2001. In general, metal levels in U. lactuca increased from January to March or April and then dropped in the following months. No periodic patterns or temporal trends of variations of metal levels in U. lactuca were found. Different metal levels in U. lactuca were comparatively lower than those in other studies in other countries and in past studies in Hong Kong. / There were significantly differences in various metal levels in different structures of Sargassum hemiphyllum, generally decreased in the following order: receptacles > vesicles > leaves > branches. / This thesis research involves biomonitoring levels of eight metal species (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in seaweed and the effects of these metals on the reproduction of Ulva lactuca. The study started from September 1999 and ended in June 2001, covering 40 intertidal sites in Hong Kong and 24 seaweed species. Environmental data on pH, salinity and nutrient levels (ammonia, nitrite, nitrate and phosphate) in seawater from these sites were also monitored. / Wong Tai Choi Richard. / "April 2005." / Advisers: P. C. K. Cheung; P. O. Ang, Jr. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0159. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 371-401). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307.

No description available.

When light intensities become supersaturating for photosynthesis, phytoplankton must be able to protect the photosynthetic machinery from potential damage by excess energy absorption. One of the most important photoprotective mechanisms involves the nonradiative dissipation of excess light energy by the interconversion of the carotenoid pigments of the so-called xanthophyll cycle. Very little is known about how the xanthophyll cycle of natural communities of phytoplankton responds to high light conditions and the relationship of this photoprotective mechanism to the surrounding physical environment. The purpose of this thesis was to examine the functioning, activation and relationship to the physical environment of the xanthophyll cycle in phytoplankton from the Antarctic ecosystem and the Southern Ocean. Experiments in Antarctica were conducted in austral spring under various natural and artificial light regimes including the use of a newly developed light mixing simulator (LMS). Photoprotective carotenoid pigment concentrations were determined using a carotenoid specific protocol for High Performance Liquid Chromatography (HPLC). The photoprotective xanthophyll cycle was not active in Antarctic sea ice algae under the low light conditions under the annual sea ice. When sea ice algae are exposed to high irradiance, there was an initial rapid deepoxidation of the xanthophyll pigment diadinoxanthin (DD) to diatoxanthin (DT). With on-going irradiance exposure, slower deepoxidation of DD continued. The recovery of DD in the dark or under low light was found to be significantly faster than in temperate algal communities, and is likely a particular adaptation to the unique light environment in Antarctica. The temporal accumulation of pigments of the violaxanthin (VX) xanthophyll cycle was observed for the first time in a natural phytoplankton population. It is hypothesized that the VX cycle may function as a pathway to maintain the pool of DD cycle pigments rather than as a separate photoprotective pathway as observed in higher plants. The high irradiances of ultraviolet - B (290 - 320 nm) radiation (UVB) as a result of stratospheric ozone depletion over Antarctica in spring was found to significantly impact on the DD cycle. Exposure to high levels of both ultraviolet-A (320- 400 nm) radiation (UVA) and UVB reduced the photoprotective xanthophyll pigment pool with the greatest reduction occurring after exposure to high levels of UVB. The reduction in the amount of cellular DD after exposure to high levels of UVB was greater than can be explained by deepoxidation activity, which implies that high UVB exposure can lead to a loss of DD from the community. The first-order kinetic rates of the DD cycle were found to be similar to other studies and did not vary with light intensity. Simulations under natural light using the LMS demonstrated that the response of the DD cycle to static in situ incubations and when subject to vertical mixing was not similar, and that static incubations overestimate DD-cycle activity Over the long term, algae in a simulated vertically mixed environment were able to increase the pool of xanthophyll pigments compared to static conditions where the pool remained the same or decreased. Oceanographic observations from the subantarctic waters south-east of New Zealand in austral autumn provided the physical background for new insights into the xanthophyll cycle of Southern Ocean phytoplankton. The circulation flow and water masses between the Bounty Plateau and Bollons Seamount was resolved and shown to differ from numerical models. Relatively little of the warm and salty Subantarctic Mode Water (SAMW) from the Tasman Sea is carried in the flow of the Subantarctic Front (SAF). The spatial distribution of photoprotective xanthophyll pigments showed higher than expected concentrations in the surface mixed layer of the region. The high concentration of photoprotective pigments is considered to be a consequence of the low iron concentrations in southern waters and the highly variable light and vertical mixing environment. The high cellular concentrations of photoprotective pigments constrains photosynthetic activity implying that the photoprotective pigments may play a more significant role in controlling phytoplankton production in the Southern Ocean than previously thought. Analysis of the xanthophyll pigments and physical oceanography with a Self-Organising map (SOM) Artificial Neural Network (ANN) showed that the photophysiological index DT/ (DD+DT) can be used to resolve a change in water type properties. A simple numerical model was developed which can be used to provide a quantitative index of the relative magnitudes of vertical mixing and phytoplankton photoprotection in the water column. This approach may be useful to identify the effects of physical changes in the surface mixed layer of the Southern Ocean as predicted by climate change modelling.

I investigated the ecological functions of halogenated secondary metabolites from the red alga Asparagopsis armata, their localisation in specialised cells and also their cost of production. A. armata produces large amounts of halogenated metabolites ( &lt 20 ??g / mg dry weight) that are sequestered in gland cells, as was demonstrated with light, epifluorescence and transmission electron microscopy. Cellular structures were identified that likely assist the release of metabolites from the gland cells to the algal surface. The halogenated metabolites of A. armata have multiple ecological roles, functioning as both inhibitors of bacterial fouling and as herbivore deterrents. Their activity against bacteria and herbivores was measured by a novel test in which the metabolites were manipulated in A. armata by omitting bromide ions from the culture media. This technique prevented the production of halogenated metabolites, but did not impact on other aspects of algal biology. Algae lacking halogenated metabolites (bromide [-] algae) had higher densities of epiphytic bacteria than those that continued to produce metabolites (bromide [+] algae). Bioassays with pure compounds against individual bacterial isolates further supported an inhibitory role for the halogenated metabolites against epiphytic bacteria, and also indicated an affect on bacterial community structure as well as abundance. Bromide (+) A. armata produced halogenated metabolites that also deterred feeding by two herbivores (an amphipod and an abalone), but not a third (an opisthobranch mollusc). A novel outcome from these feeding assays was the demonstration of a relationship between herbivore size and consumption of the chemically defended A. armata by the abalone Haliotis rubra. In addition to the fitness benefits gained from chemical defence, there were also costs for allocating resources to secondary metabolites. These costs were only detected under limiting light resources, consistent with predictions of the plant defence models. The integration of chemical analyses and cellular measures of chemical defence proved essential in elucidating resource allocation to chemical defence in the filamentous stage of A. armata. This thesis highlights that the simple relationships between growth and defence in filamentous algae can provide an excellent model for studies of the ecology and evolution of chemical defences in marine algae.

Assemblages of algae are altered by both bottom - up ( e.g. nutrient availability ) and top - down ( e.g. herbivory ) processes. As a result of the increasing human population in coastal areas, massive changes are forecast to benthic habitats in response to increasing coastal nutrient concentrations and a reduction in consumers. To identify the scales over which nutrients may have an effect, abundance of turf - forming algae growing as epiphytes on kelp ( Ecklonia radiata ) were related to water nutrient concentration across temperate Australia. In general, the percentage cover of epiphytes was greatest at sites with the greatest nutrient concentrations. By experimentally elevating mean nitrate concentration from the low 0.064 ± 0.01 µmol L [superscript - 1 ] to 0.121 ± 0.04 µmol L [superscript - 1 ], which was still only ~ 5 % of that measured on a more eutrophic coast, I was able to increase the percentage cover of epiphytes to match those seen on nutrient rich coasts, despite not matching the nutrient concentrations on those coasts. Hence, it appears that the effects of elevated nutrients will be disproportionately large on relatively oligotrophic coasts. Nutrient concentrations were also experimentally elevated to test whether the presence of an algal canopy or molluscan grazers were able to counter the effects of nutrient enrichment on algal assemblages. The loss of canopy - forming algae is likely to be a key precursor to nutrient driven changes of benthic habitats, because nutrients had no direct effect on algal assemblages in the presence of canopy - forming algae. In the absence of canopy - forming algae, space was quickly monopolised by turf - forming algae, but in the presence of elevated nutrients grazers were able to reduce the monopoly of turf - forming algae in favour of foliose algae. This switch in relative abundance of habitat may reflect greater consumption of nutrient rich turf - forming algae by grazers, possibly creating more space for other algae to colonise. Importantly, greater consumption of turf - forming algae in the presence of elevated nutrients may act as a mechanism to absorb the disproportionate effect of nutrients on oligotrophic coasts. In southern Australia, canopy - forming algae have a negative impact on the abundance of turf - forming algae. To assess the mechanisms by which an algal canopy may suppress turf - forming algae, abrasion by the canopy and water flow were experimentally reduced. Abrasion by the canopy reduced the percentage cover and biomass of turf - forming algae. In contrast to predictions, biomass and percentage cover of turf - forming algae were also reduced when water flow was reduced. Light intensity was substantially reduced when there was less water flow ( because of reduced movement in algal canopy ). However, the reduction in available light ( shading ) did not account for all of the observed reduction in biomass and percentage cover of turf - forming algae, suggesting that other factors are modified by water flow and may contribute to the loss of turf - forming algae. Habitat loss and fragmentation are well known to affect the diversity and abundance of fauna in habitat patches. I used experimental habitats to assess how fragmentation of turf habitats affects the diversity and abundance of two taxa of macroinvertebrates with different dispersal abilities. I established that increased isolation of habitats reduced the species richness and abundance of invertebrates with slow rates of dispersal, while the species richness and abundance of invertebrates with fast rates of dispersal were greatest in habitats that were far apart. In summary, this thesis provides an insight into some of the impacts associated with human populations in coastal areas, namely increased nutrient inputs, loss of grazers ( e.g. harvesting ), and loss of canopy algae and fragmentation of habitats. I show that increased nutrient concentrations in coastal waters can alter the relative abundance of algal species, and that some effects of elevated nutrients can be absorbed by the presence of grazers. I also show that elevated nutrients have no effect on algal assemblage in the presence of canopy - forming algae, and that canopies can suppress the colonisation of turf - forming algae. Finally, I show that the fragmentation of turf habitats affects taxa of invertebrates with different dispersal abilities in different ways. Whilst the contemporary ecology of much of the temperate Australian subtidal coast is considered to be relatively unaffected by human activity, this thesis shows that changes to top - down and bottom - up processes could have large consequences for habitats and their inhabitants. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

Includes index / Bibliography: p. 77-79 / i, 145 p. : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library.

"March 2004" / Bibliography: leaves 115-141. / 141. [8] leaves : ill., maps, photos (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Localised disturbance can generate considerable patchiness in the structure and composition of subtidal habitats which is a key determinant of differences in the diversity of associated assemblages of invertebrates. / Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004