Dissertations / Theses on the topic 'Marine algae as food Australia'

Detached macrophytes (sea grass and macroalgae) are transported from more offshore areas and accumulate in large volumes in surf zones, where they are commonly called wrack. In coastal regions in other parts of the world, wrack transported from one habitat to a second habitat can be considered as a "spatial subsidy" for the recipient habitat with significant consequences for community dynamics and food webs. The primary aim of this study was to determine the significance of the different components of wrack (i.e. sea grass and brown, red and green algae) as a direct and indirect food source and habitat for invertebrates and fish in surf zones of south-western Australia. The importance of different volumes of surf zone wrack to determining fish abundance and composition was also investigated. These aims were achieved by examining the food and habitat preference of invertebrates and the habitat preference of fish through laboratory trials and field experiments. Gut content analysis was used to examine the importance of wrack-associated invertebrates as a food source for fish, while stable isotope analysis (carbon, nitrogen and sulfur) and lipid analysis (lipid class and fatty acid composition) were conducted on macrophytes, amphipods and fish to determine the source of nutrients and energy. The composition of surf zone wrack in the region comprises large quantities of seagrass, then brown and red algae, with negligible quantities of green algae. Allorchestes compressa, the dominant macroinvertebrate in surf zone wrack, showed a preference for consuming brown algae over other macrophyte types. Similarly, stable isotope analysis from some locations and fatty acid analyses indicated that A. compressa assimilates nutrients predominantly from brown algae. The influence of brown algae on secondary production extends to second-order consumers. Allorchestes compressa was the major prey of juveniles of the cobbler Cnidoglanis macrocephalus and the sea trumpeter Pelsartia humeralis, the main fish species in surf zone wrack accumulations in the region. Detached brown algae therefore contributes most to the detached macrophyte - amphipod - fish trophic pathway in the surf zones, and thus drives secondary production in these regions and provides a crucial link between coastal ecosystems. Detached macrophytes also provide an important, but transient, habitat for invertebrates and fish in south-western Australia. Under laboratory conditions, Allorchestes compressa showed a strong preference for inhabiting seagrasses over macroalgae, iii however in situ caging experiments showed that A. compressa has a strong preference for brown algae, red algae or a mixture of macrophytes, but tended to avoid seagrass. Therefore, A. compressa showed a clear preference for different types of detached macrophytes as a habitat, with seagrass ranking below other types of macrophyte under field conditions. In contrast, neither Cnidoglanis macrocephalus or Pelsartia humeralis showed a preference for inhabiting different types of detached macrophytes as a habitat, but showed a strong positive influence by increasing volumes of wrack The species composition, densities and biomass of fish, which were dominated by juveniles, were strongly influenced by increasing volume of wrack in surf zones of south-western Australia. This study has shown that both the type and volume of detached macrophytes transported from more offshore regions subsidizes consumers and plays a crucial role in supporting secondary production in less productive surf-zone habitats of south-western Australia. The removal of large amounts of wrack from nearshore areas could have a detrimental impact on the biodiversity or abundance of macroinvertebrate and fish populations, which rely on wrack for food and shelter.

Thesis (M.S.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains xi, 87 p. : ill. Vita. Includes abstract. Includes bibliographical references.

Master of Science
Food Science Institute
Curtis Kastner
Harmful Algal Blooms (HABs) including Cyanobacteria and other toxic marine biota are responsible for similar harmful effects on human health, food safety, ecosystem maintenance, economic losses and liability issues for aquaculture farms as well as the food industry. Detection, monitoring and mitigation are all key factors in decreasing the deleterious effects of these toxic algal blooms. Harmful algal blooms can manifest toxic effects on a number of facets of animal physiology, elicit noxious taste and odor events and cause mass fish as well as animal kills. Such blooms can adversely impact the perception of the efficacy and safety of the food industry, water utilities, the quality of aquaculture and land farming products, as well as cause ripple effects experienced by coastal communities. HABs can adversely impact coastal areas and other areas reliant on local aquatic ecosystems through the loss of revenues experienced by local restaurants, food manufacturers as well as seafood harvesting/processing plants; loss of tourism revenue, decreased property values and a fundamental shift in the lives of those that are reliant upon those industries for their quality of life. This paper discusses Cyanobacteria, macroalgae, HABs, Cyanobacteria toxins, mitigation of HAB populations and their products as well as the ramifications this burgeoning threat to aquatic/ landlocked communities including challenges these toxic algae pose to the field of food science and the economy.

Arsenic (As) exposure through water and As contaminated food in rural areas around the world is well documented. While there are accurate, precise, and even robust screening methods for on-site water analysis, the determination of toxic inorganic As (iAs, a class I carcinogen) in foodstuff has been made possible through methods based on mass spectrometry. No screening or field method for iAs in food has been established and, there is also a lack of screening and monitoring methods for human exposure to iAs. The objectives of this thesis were to develop and apply a robust, reliable and well established screening method which is field deployable for the measurement of iAs in rice and seaweed in addition to the total As metabolites in human urine resulting from exposure to inorganic As. Reported in this work is the development and application of optimised field deployable methods based on the Gutzeit reaction with the aid of a field test kit (FTK) for the determination of iAs in rice, rice-based products, edible seaweeds and seaweeds cultivated from their natural habitat. The methods involve simple sample extraction by boiling in nitric acid before analysis with the FTK. Results were obtained in under an hour with the FTK and further validated with speciation analysis by HPLC-ICP-MS (High Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry). Analysis of 30 store-bought rice samples with the field method gave good reproducibility (± 12 %) for samples with variable As concentrations. The results were comparable to those obtained by HPLC-ICP-MS with no contribution from organoarsenicals. Screening analysis with the field method based on recent regulations for inorganic arsenic in rice also gave low false positive and false negative rates ( < 10 %) for violations against these regulations, an indication that the method can accurately identify samples that are above or below the recommended maximum contaminant limits for iAs in rice. Similarly, results from the seaweed analysis with the field method were also comparable to those from speciation analysis by HPLC-ICP-MS with limited bias between the set of data from both vii methods. Optimisation of extraction methods using a subset of samples gave 80-95% iAs recovery with no contribution from the organoarsenicals present in the samples. The determination of total As metabolites in urine from the exposure to iAs could not be done directly using the FTK. In this case, the method involved the use of UV photolysis with persulphate and titanium dioxide as oxidizing agents for the conversion of methylated As species (DMA) to the inorganic form before analysis with the FTK. A partial determination of DMA with the FTK in urine matrix was demonstrated but this needs to be studied further for the development of a robust field method for monitoring human exposure to iAs.

The cycling of arsenic in the marine photosynthetic plants and algae was examined by analysing total arsenic concentrations and arsenic species in selected marine photosynthetic organisms from the south-east coast, NSW, Australia. A range of elements required for metabolism in photosynthetic organisms were also analysed to determine if any relationship between these elements and arsenic concentrations occurred. Organisms were selected from salt marsh and mangrove ecosystems, marine inter-tidal and estuarine environments, and two species of marine phytoplankton cultured, to represent the different marine environments that primary producers inhabit. Organisms selected were compared to species within their own environment and then a comparison made between the varying ecosystems. In the salt marsh and mangrove ecosystems, the leaves of four species, the mangrove Avicennia marina, the samphire Sarcocornia quinqueflora, the seablight Suaeda australis, and the seagrass Posidonia australis were sampled from three locations from the south-east coast of NSW using nested sampling. Mean total arsenic concentrations (mean � sd) dry mass for all locations were A. marina (0.38 � 0.18 �g g-1 to 1.2 � 0.7 �g g-1), S. quinqueflora (0.13 � 0.06 �g g-1 to 0.46 � 0.22 �g g-1), S. australis (0.03 � 0.06 �g g-1 to 0.05 � 0.03 �g g-1)and P. australis (0.34 � 0.10 �g g-1 to 0.65 � 0.26 �g g-1). Arsenic concentrations were significantly different between species and locations but were consistently low compared to marine macroalgae species. Significant relationships between As and Fe concentrations for A. marina, S. quinqueflora and P. australis and negative relationship between As and Zn concentrations for S. quinqueflora could partially explain arsenic concentrations in these species. No relationship between As and P concentrations were found in this study. All terrestrial species contained predominantly inorganic arsenic in the water extractable and residue fractions with minor concentrations of DMA in the water-soluble fraction. P. australis also contained dimethylated glycerol and phosphate arsenoriboses. The presence of arsenobetaine, arsenocholine and trimethylated glycerol arsonioribose is most likely due to the presence of epiphytes on fronds on P. australis. In contrast, macroalgae contained higher total arsenic concentrations compared to marine terrestrial angiosperms. Total arsenic concentrations also varied between classes of algae: red macroalgae 4.3 �g g-1 to 24.7 �g g-1, green macroalgae 8.0 �g g-1 to 11.0 �g g-1 and blue green algae 10.4 �g g-1 and 18.4 �g g-1. No significant relations were found between As concentrations and concentrations of Fe, Co, Cu, Mn, Mo, Mg, P and Zn concentrations, elements that are required by macroalgae for photosynthesis and growth. Distinct differences between algal classes were found for the proportion of arsenic species present in the lipid and water-soluble fractions, with green algae having a higher proportion of As in lipids than red or estuarine algae. Acid hydrolysis of the lipid extract revealed DMA, glycerol arsenoribose and TMA based arsenolipids. Within water-soluble extracts, red and blue-green algae contained a greater proportion of arsenic as inorganic and simple methylated arsenic species compared to green algae, which contained predominantly glycerol arsenoribose. Arsenobetaine, arsenocholine and tetramethylarsonium was also present in water-soluble extracts but is not normally identified with macroalgae and is again likely due to the presence of attached epiphytes. Residue extracts contained predominantly inorganic arsenic, most likely associated with insoluble constituents of the cell. Mean arsenic concentrations in the green microalgae Dunaliella tertiolecta were 13.3 �g g-1 to 14.5 �g g-1, which is similar to arsenic concentrations found in green macroalgae in this study. Diatom Phaeodactylum tricornutum arsenic concentrations were 1.62 �g g-1 to 2.08 �g g-1. Varying the orthophosphate concentrations had little effect on arsenic uptake of microalgae. D. tertiolecta and P. tricornutum metabolised arsenic, forming simple methylated arsenic species and arsenic riboses. The ratio of phosphate to glycerol arsenoriboses was higher than that normally found in green macroalgae. The hydrolysed lipid fraction contained DMA arsenolipid (16-96%) with minor proportions of phosphate arsenoribose (4-23%). D. tertiolecta at f/10 phosphate concentration, however, contained glycerol arsenoribose and another arsenic lipid with similar retention as TMAO as well as DMA. The similarities between arsenic species in the water-soluble hydrolysed lipids and water-soluble extracts, especially for P. tricornutum, suggests that cells readily bind arsenic within lipids, either for membrane structure or storage, releasing arsenic species into the cytosol as degradation of lipids occurs. Inorganic arsenic was sequestered into insoluble components of the cell. Arsenic species present in D. tertiolecta at lower phosphate concentrations (f/10) were different to other phosphate concentrations (f/2, f/5), and require further investigation to determine whether this is a species-specific response as a result of phosphate deficiency. Although there are similarities in arsenic concentrations and arsenic species in marine photosynthetic organisms, it is evident that response to environmental concentrations of arsenic in uncontaminated environments is dependent on the mode of transfer from the environment, the influence of other elements in arsenic uptake and the ability of the organism to metabolise and sequester inorganic arsenic within the cell. It is not scientifically sound to generalise on arsenic metabolism in �marine plants� when species and the ecosystem in which they exist may influence the transformation of arsenic in higher marine organisms. There is no evidence to suggest that angiosperms produce AB as arsenic is mostly present as inorganic As, with little or no arsenic present in the lipids. However, marine macro- and microalgae both contain lipids with arsenic moieties that may be precursors for AB transformation. Specifically, the presence of TMA and dimethylated arsenoribose based arsenolipids both can transform to AB via intermediates previously identified in marine organisms. Further identification and characterization of As containing lipids is required.

Lake Illawarra is a shallow barrier lagoon, located on the south-eastern coast of Australia. Eutrophication, referring to the enrichment of water by inorganic plant nutrients (primarily nitrogen and phosphorus), is one of the key environmental problems in Lake Illawarra. Management of macroalgae in Lake Illawarra is a major issue; excessive blooms of macroalgae, resulting in odours, access problems and community concern over Lake health, have led to many management strategies, including direct harvesting of algal biomass. Little information is available on the factors responsible for excessive growth of macroalgae in Lake Illawarra, although over supply of nutrients has often been cited as the primary cause. The aim of this study was to investigate the distribution, diversity, biomass and nutrient relationships of seagrasses and macroalgae in Lake Illawarra, and to determine what contribution, if any, macrophytes make to the Lake’s nutrient budget. Firstly, detailed species lists and taxonomic descriptions were prepared for macrophytes occurring in Lake Illawarra, between June 2000 and July 2003. This study focused primarily on shallow (< 1 m depth), inshore areas of Lake Illawarra, where problematic macroalgal blooms frequently occur. Seagrasses found in Lake Illawarra are Zostera capricorni, Ruppia megacarpa, Halophila ovalis and Halophila decipiens. In addition, 35 species of macroalgae were recorded and described; these included: 14 species from 7 genera of green macroalgae; 9 species from 9 different genera of brown macroalgae; and, 8 species from 8 genera of red macroalgae. The biomass of seagrasses and macroalgae in Lake Illawarra were documented seasonally (winter and summer) at four key Lake Illawarra sites; these included two R. megacarpa sites and two Z. capricorni sites. Average R. megacarpa and Z. capricorni dry weight (DW) biomasses (above and below-ground material) ranged from 54.8 - 440 g DW m 2 and 58.1 - 230 g DW m 2, respectively. Significant die-back, particularly of Z. capricorni, occurred in winter; summer biomasses were up to 1.5 - 3.9 times higher than winter biomasses. Below-ground material (roots and rhizomes) comprised 20 - 45 % and 40 - 67 % of total plant biomass for R. megacarpa and Z. capricorni, respectively. Macroalgal biomass in 2000-03 was notably lower than in previous decades; this may be due to drought, as well as improvements in water quality. Maximum biomasses of macroalgae recorded in the present study were 150 - 370 g DW m 2. Algal blooms were composed primarily of the filamentous chlorophytes, Chaetomorpha linum and Chaetomorpha billardierii. The highest seagrass (R. megacarpa) and macroalgal biomasses usually occurred at the Oasis Caravan Park site, located along the eastern Lake Illawarra peninsula. Tissue nutrient analyses were conducted on the most abundant seagrasses (Z. capricorni and R. megacarpa) and macroalgae occurring at four sites in Lake Illawarra, between spring 2000 and winter 2002. Total C contents of macrophytes varied from 23.3 - 42.0 % C for seagrasses, and 28.0 - 39.7 % C for macroalgae. The δ13C and δ15N contents of seagrasses ranged from -7.7 to 15.9 ‰ and 0.7 - 9.0 ‰, respectively. The most significant seasonal variations in seagrass δ13C contents and, to a lesser extentδ15N contents, occurred in Z. capricorni located at the source of fresh water input, Mullet Creek. Macroalgae showed a greater variation in isotopic signatures than the seagrasses, ranging from 4.9 to 19.8 ‰ (δ13C) and 1.8 - 14.6 ‰ (δ15N). Differences between species at the same site were often more significant than differences between the same species at different sites. Seagrass leaf N and P contents ranged from 1.74 - 4.13 % (mean ± s.e.: 2.62 ± 0.05 % N) and 0.12 - 0.59 % P (mean ± s.e.: 0.31 ± 0.01 % P); leaf N and P contents were typically double those of roots/rhizomes. N contents varied between species and sites, but P contents of Z. capricorni were usually significantly higher than R. megacarpa. Z. capricorni C and N contents increased in winter, corresponding to lower winter biomasses. Seagrass leaf biomass and tissue P contents peaked in summer 2002, which may be related to higher water column P concentrations in summer. Tissue N and P contents of macroalgae were more variable than those of the seagrasses, and ranged from 0.85 - 3.95 % N and 0.03 - 0.58 % P. The average C/P (808 ± 65) and N/P (47.9 ± 3.47) molar ratios of macroalgae were typically double those of the seagrasses. Low concentrations of tissue P, with respect to N, in R. megacarpa and macroalgae implied P limitation on several occasions, particularly when macrophyte biomasses were low. High tissue N contents in Lake Illawarra macrophytes suggested N limitation of biomass formation rarely occurred. Evidence of P, rather than N, limitation in macrophytes is surprising considering most data suggests N limitation of phytoplankton production in Lake Illawarra. The estimated pools of N and P contained in Lake Illawarra macrophyte biomass were similar to those present in the water column, but appeared minute when compared to the N and P stored within Lake Illawarra sediment. Laboratory culture experiments were conducted to evaluate the response of the most problematic alga, Chaetomorpha linum, to nutrient enrichment. Water temperatures of 20 - 25°C were found to promote the highest growth rates (up to 27 % WW d 1) of C. linum, but high growth rates (13 % WW d 1) were also recorded at 10°C, the lowest winter water temperature recorded in Lake Illawarra. Enrichment with N, rather than P, had the greatest effect on C. linum; growth rates were significantly reduced in treatments without added N, but treatments with N-alone were statistically similar to N+P treatments. It was concluded that in Lake Illawarra, C. linum was strongly nitrogen limited. The ability of C. linum to grow successfully in culture, under a range of nutrient treatments, and without added phosphorus, in particular, correlates with the excessive growth of this alga in Lake Illawarra. This study has made a significant contribution to the understanding of seagrass and macroalgal growth, biomass and distribution in Lake Illawarra. This information will assist with the long-term management of macroalgal problems in Lake Illawarra.

Generalist herbivores profoundly influence the biomass and species composition of macroalgae assemblages. In subtidal ecosystems of temperate latitudes, large invertebrates are usually the most influential herbivores. I tested the prediction that exclusion of invertebrate herbivores would lead to changes in the biomass and species composition of the macroalgae assemblages that are a prominent feature of the reefs in south-western Australia. The most abundant invertebrate herbivores were sea urchins (Heliocidaris erythrogramma, Phyllacanthus irregularis and Centrostephanus tenuispinus), and these occupied different trophic positions. Heliocidaris was present at virtually all reefs surveyed, and was particularly abundant in the Fremantle region. Analyses of stable isotopes and direct observations of gut contents revealed that it was almost exclusively herbivorous, and that it mainly ate foliose brown algae. In contrast, Phyllacanthus and Centrostephanus were omnivorous; while they consumed large proportions of algae, a substantial proportion of the diet of both species was animal tissue. Because Heliocidaris is a generalist herbivore that occurs at high densities, it could exert a large influence on the macroalgae assemblage. This prediction was tested by a series of press experiments. Contrary to the prediction, Heliocidaris exerted a very minor influence on the biomass, and no detectable influence on the species composition, of attached macroalgae. However, it exerted a major influence on the retention of drift macroalgae and seagrass by trapping and feeding on drift. It exerted a particularly strong influence on retention of the kelp Ecklonia radiata. This kelp was not abundant in the attached algae assemblage (when all plots were pooled it ranked 35th in biomass), but was abundant as drift (ranking 1st). Most of the drift Ecklonia was retained by sea urchins, rather than freely drifting.Herbivorous fish may also influence macroalgae assemblages. To compare the effects of sea urchins versus fish on recruiting and adult macroalgae a 13-month exclusion experiment was conducted. There were no detectable effects of sea urchins (mainly Heliocidaris) on either recruiting or adult macroalgae. There were some patterns in the biomass of recruiting algae consistent with an influence by herbivorous fish; however, these patterns were also consistent with the presence of artefacts (shading and reduced water flow) by fish exclusion devices. I began with the prediction that large invertebrate herbivores were a major influence on the macroalgae assemblages of subtidal reefs in south-western Australia. Overall, there was little evidence to support this prediction: within spatial extents of tens of square metres and over periods of 1-2 years, only minor effects were detected. However, it remains plausible that herbivores exert an influence over long time periods across large spatial extents in south-western Australia. I propose that trophic subsidies support the comparatively high densities of Heliocidaris that exist at some reefs. I further propose that these subsidies mediate the effects of sea urchins on the attached macroalgae assemblage, and that they might play an important role in energy and nutrient cycling in these nearshore ecosystems.

[Truncated abstract] The role of marine microzooplankton in aquatic food webs has been studied in most regions of the world’s oceans, with the exception of the subtropical/temperate eastern Indian Ocean. This thesis addresses this gap in knowledge by investigating microzooplankton from five stations on a cross continental shelf transect and in two mesoscale features ∼300 km offshore of south west Western Australia. My primary focus was to measure and evaluate microzooplankton community change over space and time and their impact on phytoplankton on a cross shelf transect, sampling five stations from February 2002 December 2004 as part of a large multidisciplinary investigation into the pelagic ecosystem on the shelf (Chapter 2). This transect was named the Two Rocks transect. I also investigated an eddy pair (Chapter 5), which had originated from water in the vicinity of the Two Rocks transect, also undertaken as part of a larger study, investigating biophysical coupling within mesoscale eddies off south west Western Australia . . . The distribution of mixotrophic cells differed across the transect. Those mixotrophs that use photosynthesis as their primarily energy source exploited nutrient limited conditions inshore consuming particles, while mixotrophs that are primarily heterotrophic survived low prey conditions offshore by photosynthesizing. In the eddies, the grazing behaviour of microzooplankton was dependent on the specific phytoplankton assemblage in each eddy. The warm core eddy had a resident population of diatoms that were consumed by heterotrophic dinoflagellates present in high numbers. The cold core eddy had a warm cap which prevented upwelled water reaching the surface, resulting in stratification and a very active microbial food web, particularly in the surface.

The purpose of this study was to identify if terrestrial arthropod predators on Baltic Sea shores vary in their use of marine versus terrestrial food items, and to construct a bottom-up food web for Baltic Sea shores. The inflow of marine nutrients in the area consists mainly of marine algal detritus and emerging aquatic insects (e.g. phantom midges, Chironomidae). Diets of coastal arthropods were examined using carbon and nitrogen stable isotope analysis, and a two source mixing model was used to examine proportions of marine carbon to diets. The results suggest that spiders are the terrestrial predators mainly utilizing nutrients and energy of marine origin on Baltic Sea shores, while insect predators such as beetles and hemipterans mainly utilize nutrients and energy derived from terrestrial sources, possibly due to differences in hunting behaviour. That spiders are the predators that benefit the most from the marine inflow suggest that eventual effects of marine subsidies for the coastal ecosystem as a whole are likely mediated by spiders.

Recreational line fishing is highly targeted at predatory fishes, making them vulnerable to overfishing. These same fishes play a role in trophic structure by regulating prey species. Despite increasing numbers of fishers, few studies have investigated the potential effects of recreational fishing on fish populations and subsequent trophic effects. This project investigated whether there were differences in fishes and benthos between unfished and recreationally fished areas, and whether the removal of targeted fishes influenced trophic structure. The study was conducted at the Ningaloo Marine Park, Western Australia, which had Sanctuary (no-take) and Recreation {recreationally fished) Zones. Data were collected from three regions (Mandu, Osprey and Maud) and replicated over time. Fish assemblages, benthos and trophic interactions were compared between zones at each region. At Ningaloo the lethrinids (emperors) are a top-order predatory fish and the preferred target of recreational anglers. The algal-grazing urchin Echinometra mathaei comprised 51% of macro invertebrate abundances and was heavily preyed upon by lethrinids, being recorded in 50% of the guts of sampled fish. In nil regions, Sanctuary Zones had a greater biomass of lethrinids than Recreation Zones, but there were no differences in non-targeted fishes between zones. Despite the consistent effect on lethrinids, there were inconsistencies among regions in the predator-prey relationships. At Mandu, Echinometra mathaei abundances were inversely related to lethrinid biomass, suggesting a strong predator-prey interaction. In the Recreation Zone, the abundances of E. mathaei were four times greater, and macro-algal cover was half, that of the Sanctuary Zone. Furthermore, algal composition differed between zones, and this was driven by fucoid brown algae, which dominated the diets of E. mathaei. This was interpreted as evidence of a trophic cascade resulting from the removal of lethrinids at the Recreation Zone. At Maud, different results were recorded. Abundances of Echinometro mathaei and lethrinids were both higher in the Sanctuary Zone, than the adjacent Recreation Zone. E. mathaei reside in the crevices of rock, dead coral or Echinapora coral, which provided refuge from predation and this habitat was more available in the Sanctuary Zone. It is suggested that the availability of this habitat confounded the effects of predation. Macro- algal cover was lower in the Sanctuary Zone indicating a grazing effect from E. mathaei. At Osprey there was higher cover of E. mathaei habitat in the Sanctuary than the Recreation Zone. However, there were no differences in macro-algal cover, which was consistent with a lack of difference in E. mathaei abundances. The effect of E. mathaei grazing was unlikely to have been confounded by fishes that graze macro-algae, as they did not differ between zones at any region. These results indicate that recreational fishing reduced fish populations below that of adjacent protected areas at Ningaloo Marine Park, and in one region this resulted in a trophic cascade. This may be the first study that has recorded evidence of a trophic cascade where recreational line fishing is the only means of extraction. However, the results also show that this is not a consistent response to reduced fishing pressure; in other regions, changes in predatory fish abundance did not result in differences in the abundances of their prey, suggesting no trophic cascade. The studies have contributed towards an understanding of fish-habitat interactions and provide a baseline for future monitoring of the Ningaloo Marine Park. They also have important implications for marine park managers in terms of defining their expectations when implementing Sanctuary Zones. The results also show that Sanctuary Zones have the potential to be effective tools for fisheries management.

[Truncated abstract] Kelp beds of South-Western Australia have high alpha (within habitat) diversity, through high species turnover at small spatial scales. The E. radiata canopy has a strong negative influence on the diversity of the understorey through intense interspecific competition for light. Literature suggests that when the competitively dominant species such as E. radiata are physically removed, diversity will increase, as less competitive species become more abundant. Apart from disturbance, evidence suggests that reef topography at the 1-10 m vertical scale also has an influence on the structure of the kelp beds, particularly in reference to relative abundance of canopy algae and species richness of the assemblage. In this thesis, I explore the role of algal assemblage recovery from physical disturbance to maintain high diversity. I also investigate the influence of reef structure (in terms of topography at the 1-10 m vertical scale) on assemblage recovery. This thesis provides a valuable functional explanation for the high diversity observed in South-Western algal assemblages. In addition, it explores the influence of reef topography which has received little attention to date . . . Overall, this thesis argues that the high alpha diversity in algal assemblages of South-Western Australia is due to local scale processes including disturbance and assemblage recovery which generate diversity by the creation of species rich gap states and by phase-shifts during the recovery process, creating a mosaic of different patch types. Assemblage recovery is composed of several processes, including survival of juvenile kelp sporophytes and canopy shading, added to macroalgal diversity through spatial and temporal variation in their outcomes. Reef topography contributed to algal diversity by influencing the processes associated with assemblage recovery through alteration of key physical variables including light levels and water motion.

Sodwana Bay, situated within the iSimangaliso Wetland Park, is ecologically important as it contains high-latitude corals and the most southerly known population of coelacanths. This thesis utilised stable isotope and lipid analyses to investigate the trophic ecology of the area, in particular, understanding the relative contribution of inshore and offshore primary production to consumers inhabiting intertidal and shallow subtidal, coral reef, deep reef, canyon head and pelagic habitats. Seaweeds, excluding certain species of red seaweeds with highly depleted carbon signatures, and phytoplankton, such as diatoms, were found to be the principal sources of primary production for all consumers. Offshore production was typified by dinoflagellates. Particulate organic matter (POM) was spatio-temporally variable. Three distinct productivity periods related to nutrient cycling were noted with enriched carbon signatures and higher organic matter loads associated with warmer water. Inshore primary production was an important source of carbon to consumers in all habitats with the exception of zooplankton that were more reliant on pelagic primary production. Benthic invertebrates reflected a gradient in the utilisation of inshore production, due to the reduced availability of this source further offshore. Consumers at the furthest sites offshore were found to include a substantial quantity of inshore-derived production in their diets. Fishes, which are more mobile, were found to incorporate a similar proportion of inshore production into their diets regardless of where they were collected from.

Pomacentridae is one of the most representative families of herbivorous fishes inhabiting both tropical and temperate reefs, yet the vast majority of studies examining feeding within this family have been undertaken in tropical rather than temperate regions. Despite the high abundances of the pomacentrid Parma mccullochi in temperate waters of Western Australia, and their likely importance in removing algae from reefs in the region, there is a lack of information on their diet and their impact on the reef algal community. This study aims to determine the role of Parma mccullochi as an ecosystem engineer on temperate algal-dominated reefs in the metropolitan waters of Perth, Western Australia. To achieve this, the diet of P. mccullochi and any ontogenetic differences, and its impact on the reef in terms of algal composition and algal recruitment were determined. P. mccullochi in the temperate reefs of Western Australia was found to be a strict herbivore, with its diet comprising almost entirely red foliose and filamentous algae such as Hypnea spp., Ceramium sp. and Brongniatrella sp., and showing no ontogenetic shift. Based on electivity indices, P. mccullochi showed a positive selection for specific algal taxa such as Brongniartella sp., Dasyclonium sp., Hypnea spp. and Dictyopteris spp. The species composition of macroalgae differed significantly between inside and outside P. mccullochi territories (P = 0.010), and a caging experiment in P. mccullochi territories indicated a moderate effect on the composition of recruiting algae (P = 0.067). Algal assemblages inside the territories were characterised by Hypnea spp. and Dasyclonium spp., while those outside the territories were characterised by the brown algae Ecklonia radiata and Sargassum spp., the foliose red alga Rhodimenia sonderi and the coralline red alga Amphiroa anceps. Total algal biomass was significantly lower (P = 0.0126) while species richness was higher (P = 0.0114) inside compared to outside territories. This study, therefore, provides the evidence to refute the theory that temperate Pomacentridae have a low impact on the temperate reefs (Jones 1992). P. mccullochi has the capacity to structure the benthic composition of reefs and maintain high biodiversity patches within kelp canopies. This effect is amplified by the high abundances of the species observed in Perth metropolitan waters, and can therefore be considered an ecosystem engineer/landscaper of temperate algal dominated reefs, highlighting its importance in ecosystem processes of temperate reefs in the region.

This study documented the macroalgal assemblages of the Swan-Canning Estuarine System (SCES) over a two year period, and the influences of several environmental parameters on the assemblages. In addition, the Impacts of unattached macroalgal accumulations on benthic nutrient fluxes and microbial communities were investigated. Benthic macroalgal assemblages and physico-chemical regimes were monitored in the SCES, to determine temporal and spatial changes in macroalgal communities and the influence of environmental factors in these changes. Physico-chemical regimes demonstrated strong seasonal changes, which revolved around the onset and cessation of freshwater flows in winter (May to September). In the months after freshwater flows, strong spatial variability in physico-chemical profiles was observed. However, by summer the system was essentially marine. Macroalgal biomass and species richness was lowest in winter. Species number was maximal during periods of greatest hydrological variability in the estuary (spring and autumn). It may be inferred from results of statistical analyses that substrate type (i.e. hard/soft) and waterflow were the most Influential factors over temporal and spatial distribution of macroalgal species in the SCES. These factors ware reflected by the patchiness of macroalgal distribution in the system- attached macroalgal species distributed unevenly according to availability of limited hard substrate and presence/absence of unattached macroalgal species corresponding to seasonal freshwater flows. One species, Gracileria comosa, dominated macroalgal biomass and was the most widespread species and commonly occurred as extensive, unattached accumulations. As G. comosa was the most abundant unattached macroalga, accumulations of this species were investigated to determine the characteristics and behaviour or accumulations in the Swan-Canning Estuarine System. Accumulations were characterised by seasonally measuring height and biomass of accumulations in three regions or the estuarine system over one year. The height of accumulations was generally between 5 and 25cm, regardless of water depth, location, or season. Biomass was highly variable, but generally between 100 and 500 dw/m2 . The persistence of macroalgal accumulations was monitored at 28 sites within 10 estuarine regions, over a three month period, during which the first freshwater flows were recorded. Accumulations persisted between one week and one month, depending on the region, with accumulations persisting for longer periods in areas of low flow such as embayments and the regulated Canning River, and for shorter periods In regions of higher flow such as the channalised Swan River. Field and laboratory studies were performed to determine If the presence of G. comosa accumulations had an Impact on sediment-water nutrient exchange. Field studies established that accumulations affected benthic nutrient fluxes within a 24 hour period. However, this effect was site-dependent, occurring at an estuarine site of relatively high sediment organic content, but not at a site of relatively low sediment organic. Diurnal changes in water quality inside algal accumulations corresponded to photosynthetic/respiratory activity of the macroalgae - most notably, Increases In orthophosphate and ammonium fluxes from the sediment after approximately 8h of darkness. Since this effect was on time scales less than the period of persistence (weeks to months), It was concluded that macroalgal accumulations have an impact on benthic nutrient fluxes from sediments of relatively high organic content in the system. Laboratory studies investigated the effect of depth and density of an algal layer on sediment- water nutrient exchange. The experimental results concurred with field observations; water column concentrations of inorganic nutrients were significantly higher in sediment cores overlain by an algal layer over a 7 day period. In addition, Inorganic nutrient concentrations increased With Increasing height of the layer and ammonium concentrations increased with increasing density of the algal layer. Additional laboratory experiments tested the effect of an algal layer on sediment denitrification rates, and the composition and distribution of benthic microbial populations, Benthic nitrogen (N2) release rates were low irrespective of the presence of macroalgae and sediment types (less than 1mmo N/m2/d). However, release rates were significantly higher in sediment cores covered by algae than in comparable bare sediment cores, provided the algal layer was relatively high (5cm in height} and sediment organic content was high. The presence of an algal layer did not have a significant effect on the composition or distribution of microbes in the sediment. In all cases, microbial populations contained relatively few denitrifiers/nitrate reducers compared to nitrifiers and ammonifiers. High ammonium release rates from the sediment to the water column, and the low release rates of elemental nitrogen, suggested that even II the nitrate reducing bacteria were active they were not reducing nitrate to nitrogen, suggesting the possibility of Dissimilatory Nitrate Reduction to Ammonium (DNRA). Subsequent analysis confirmed that the nitrate reducers were reducing nitrate to nitrite, a result compatible with the hypothesis that the main microbial processes occurring were ammonification, nitrification, and DNRA, but not denitrification. These processes, regardless of the presence of a benthic algal layer, contribute to high ammonium flux rates from the sediment and provide a mechanism of internal inorganic nitrogen regeneration. In conclusion, this study has established that unattached macroalgal accumulations are a prominent component of the macroatgal community in the Swan-Canning Estuarine System. Accumulations may remain within an estuarine region for up to one month, particularly in regions of low water flow. In seasons and regions of relatively high water flows (e.g. the Swan River), accumulations become highly transient, if present at all. At times, and in regions where they may persist, algal accumulations of 5cm or more in depth have an impact on benthic nutrient fluxes. In particular, their presence over sediments of high organic content appears to exacerbate the release of ammonium from the sediment to the overlying water column. Of note, the benthic process Dissimilatory Nitrate Reduction to Ammonium appears to dominate in summer while denitrification rates are minimal, regardless of the presence of a macroagal layer. From these findings, it is recommended that high fluxes of ammonium in the system be recognised In water quality management and nutrient budgets for the system, as It appears that Internal ammonium regeneration Is a large source of Inorganic nitrogen for organisms In the overlying water body, and may support algal blooms In summer. In addition, it appears that the most appropriate method of managing macroalgal distribution and biomass in the system is ensuring strong freshwater flushes during winter periods when macroalgal biomass is largely removed. If seasonal flushes were inhibited, it is predicted that macroalgal biomass and distribution would increase, extending the period that thsy can influence benthic nutrient cycles. The physical removal of macroalgae as a management option in such a scenario would require much time and effort, as the Swan-Canning Estuarine System is such a large system, and macroalgae are spread throughout. Therefore, in modifying river flows into the estuarine system, the quantity, composition and distribution of macroalgae, and possibly other flora and fauna, will be altered. This is already evident in the Canning River, which is regulated and suffers management problems, such as altered species composition, bathymetric changes, toxic algal blooms, and eutrophication.

Measurements of carbon (13C/12C; δ13C) and nitrogen (15N/14N; δ15N) stable isotope ratios have become important tools for: estimating energy flow and trophic positions in aquatic foodwebs; comparing food webs; and aiding in the tracking of wide-ranging consumers. However, each of these applications requires accurate measurements of isotopic signatures in organisms at or near the base of the food web (e.g. autotrophs and their consumers), which act as basal reference points from which to calibrate inferences. Therefore, understanding variations in isotopic baselines, and the mechanisms leading to their variability, is crucial for food web ecology. Using the shallow temperate reefs along the lower west coast of Australia as a test case, the broad aim of this thesis was to determine isotopic variations in a coastal food web and their relationship with surrounding environmental factors or food sources, to determine the suitability and issues for using such baselines in interpreting trophic links and positions in food webs and predicting shifts in isotopic signatures across broad spatial and temporal scales. To achieve this, I have determined the critical scales for accurately capturing baseline isotopic variation in ecologically important autotrophic and consumer taxa (e.g. macroalgae, particulate organic matter and suspension and grazing consumers), and then related isotopic variation in macroalgae to properties of their surrounding physical and biogeochemical environment. I have then used these relationships to project and forecast baseline values in space and time. Lastly, I have tested the suitability of different primary consumers, representing suspension and grazing functional groups to capture spatial and temporal isotopic variation of their respective diets, to act as invariable proxies of δ13C and δ15N baselines. Isotopic variability of basal resources differed between autotrophs and consumers, and among species within these groups, and between isotopes (i.e. δ13C and δ15N), demonstrating the difficulty in capturing accurate and representative values. Spatial patterns for the δ13C and δ15N in the kelp Ecklonia radiata, the δ15N in the calcareous red alga Amphiroa anceps, and the δ13C in the ascidian Herdmania momus and the bivalve Septifer bilocularis, were influenced by variation at replicates (10s of m) and sites (1s of km) over regions (10s of km). Whereas, the reverse was true for δ13C and δ15N in the foliose red alga Plocamium preissianum, δ15N in S. bilocularis, and δ13C in the gastropod Turbo torquatus, with regional differences being the greatest source of influence. Temporally, patterns of δ13C and δ15N variation in each taxon and trophic group were more comparable, with seasonal variation eliciting a weak or negligible effect, but monthly variation often resulting in a strong effect. Temperature, light, water motion, and measurements of dissolved inorganic carbon, nitrogen and phosphorous correlated with spatial and temporal variation in the stable isotopes of macroalgae, but these relationships varied with taxa and isotope. Surprisingly, water temperature was the best single explanatory variable, accounting for ~50-60% of variation in the δ13C and δ15N of P. preissianum, and the δ15N of E. radiata and A. anceps. From the above relationships, spatial predictions of δ13C and δ15N values in macroalgae showed clear latitudinal patterns, which covered a far wider range of values than temporal predictions, over a 12-month period. This illustrates the potential scale in the shift of isotopic baseline food sources over broad scales, and its implications for food web studies. Primary consumers, particularly the bivalve Septifer bilocularis and the gastropod Turbo torquatus, generally mitigated a large proportion of the autotrophic δ15N variation and displayed relatively stable δ15N over time, and appeared to time-integrate the δ15N of their diet. Further, by conducting a controlled feeding study, I showed that S. bilocularis exhibited slow δ15N turnover estimates (e.g. half-life of 56 days), which from simulations, negated and “dampened” the effect of fluctuating δ15N values of food sources. This suggests that, owing to their high abundances and wide distributions, these species can be used to compare δ15N baselines over large spatial scales. However, this was not the case for δ13C, where primary consumers were as variable as those autotroph(s) they are assumed to proxy. Therefore, consistency in consumer δ15N does not necessarily equate to consistency in δ13C. The fact that different autotrophs and consumers elicit different patterns of variation, show that sampling designs need to be compatible to the research questions of interest. Otherwise, improper allocation of sampling effort may decrease the probability of detecting ecologically important differences. Consequently, my results provide a reference from which to determine the appropriate sampling design to capture variation in ecologically important taxa, to help inform future studies. Further, the models I have developed to predict isotopic values for important autotrophic sources, and the identification of reference taxa of baseline δ15N (bivalves and gastropods), could be used by ecologists to remove a large proportion of unexplained variation, thus facilitate the interpretation of variation in stable isotopes of consumers in food webs, to help answer important questions in food web ecology.

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.

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.

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.

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.

The thesis investigates members of the crustose and largely calcified red algal family Peyssonneliaceae through molecular analyses and anatomical and ultrastructural observations. Mitochondrial CO1 DNA barcoding was implemented, in combination with fine-scale anatomy, to recognise species boundaries and identify complexes of cryptic species. Nuclear and organellar DNA markers were employed to construct a multigene phylogeny for Vanuatu and southern Australian members of the family facilitating the recognition of two undescribed genera Annea and Incendia.

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

Fatty acid (FA) analysis is a powerful ecological tool for examining trophic relationships among marine organisms. Its application in benthic food webs may be limited because many benthic organisms consume a highly mixed diet, and FA metabolism of benthic invertebrates may obscure dietary markers. This thesis examines the use of FA as dietary tracers for studying the diets of benthic invertebrates and the fate of primary production in rocky subtidal food webs. In Chapter 2, I review the use of FA for studying benthic marine food webs, and suggest that field studies using FA analysis should also include data from controlled feeding experiments, gut contents, or stable isotope analysis to provide more reliable results. In Chapter 3, I compare FA composition among sea urchins fed four natural algal diets in a controlled feeding study. These sea urchins substantially modified their dietary FA but differed in their overall FA composition according to diet. In Chapter 4, I use FA to trace the invasive alga Codium fragile ssp. fragile and the native kelp Saccharina longicruris through two trophic transfers in an experimental food web. Substantial signal attenuation occurred with each trophic transfer, suggesting that FA analysis may be of limited use for tracing benthic primary producers in field studies. In Chapter 5, I use FA in conjunction with stable isotope analysis and gut contents analysis to investigate the contribution of detrital kelp to the diet of sea urchins in habitats adjacent to kelp beds. FA analysis was unable to distinguish among sea urchins at different distances from the kelp bed, but the results of all analyses indicated that the availability of kelp detritus declines with distance from the kelp bed, and that sea urchins in low-productivity habitats rely on both kelp detritus and benthic diatoms. In Chapter 6, I summarize the overall findings and suggest experimental and statistical methods to address some of the problems associated with using FA analysis to study trophic relationships in benthic food webs.

by Li Yung Yung.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 105-121).
Abstracts in English and Chinese.
ACKNOWLEDGEMENTS --- p.i
ABSTRACT (ENGLISH VERSION) --- p.ii
ABSTRACT (CHINESE VERSION) --- p.iv
TABLE OF CONTENTS --- p.v
LIST OF TABLES --- p.x
LIST OF FIGURES --- p.xi
LIST OF ABBREVIATIONS --- p.xiii
Chapter CHAPTER ONE --- INTRODUCTION
Chapter 1.1 --- Seaweed --- p.1
Chapter 1.1.1 --- General Introduction --- p.1
Chapter 1.1.2 --- Classification and Use of Seaweed --- p.1
Chapter 1.1.3 --- Phycocolloids --- p.2
Chapter 1.1.4 --- Hong Kong Seaweed --- p.3
Chapter 1.1.4.1 --- Sargassum Species --- p.3
Chapter 1.1.4.2 --- Padina Species --- p.5
Chapter 1.2 --- Source and Production of Alginate --- p.8
Chapter 1.2.1 --- Function of Alginate in Seaweed --- p.8
Chapter 1.2.2 --- Chemical Structure of Alginate --- p.8
Chapter 1.2.3 --- Alginate Production --- p.9
Chapter 1.2.4 --- Isolation of Alginate --- p.13
Chapter 1.2.5 --- Commercial Methods --- p.13
Chapter 1.3 --- Application of Alginate --- p.14
Chapter 1.3.1 --- Industrial Application --- p.14
Chapter 1.3.2 --- Pharmaceutical Application --- p.16
Chapter 1.3.3 --- Food Application --- p.17
Chapter 1.3.3.1 --- Uses of Alginate in Food --- p.17
Chapter 1.3.3.2 --- Safety --- p.19
Chapter 1.4 --- Structure and Function Relationship of Alginate --- p.19
Chapter 1.4.1 --- Physico-Chemical Properties --- p.21
Chapter 1.4.1.1 --- M/G ratio --- p.21
Chapter 1.4.1.2 --- Solution Properties --- p.21
Chapter 1.4.1.3 --- Viscosity --- p.23
Chapter 1.4.1.4 --- Molecular Weight --- p.27
Chapter 1.4.2 --- Functional Properties --- p.27
Chapter 1.4.2.1 --- Emulsion --- p.27
Chapter 1.4.2.2 --- Gel Properties --- p.27
Chapter 1.4.2.3 --- Mechanism of Gelation --- p.29
Chapter 1.4.2.4 --- Gel Strength and Syneresis --- p.30
Chapter 1.5 --- Physiological Effects --- p.32
Chapter 1.5.1 --- Dietary Fibre --- p.32
Chapter 1.5.2 --- Minerals --- p.32
Chapter 1.6 --- Significance of the Present Study --- p.33
Chapter CHAPTER TWO --- MATERIALS AND METHODS
Chapter 2.1 --- Seaweed Collection --- p.36
Chapter 2.2 --- Sample Preparation --- p.36
Chapter 2.3 --- Alginate Extraction --- p.38
Chapter 2.3.1 --- Method A --- p.38
Chapter 2.3.2 --- Method B --- p.38
Chapter 2.3.3 --- Commercial Alginate --- p.39
Chapter 2.4 --- Chemical Composition of Alginate --- p.41
Chapter 2.4.1 --- Alginate Content --- p.41
Chapter 2.4.2 --- Moisture Content --- p.41
Chapter 2.4.3 --- Crude Protein Content --- p.41
Chapter 2.4.4 --- Ash Content --- p.42
Chapter 2.4.5 --- Monosaccharide Composition --- p.42
Chapter 2.4.5.1 --- Acid Deploymerisation --- p.42
Chapter 2.4.5.2 --- Neutral and Amino Sugar Derivatization --- p.42
Chapter 2.4.5.3 --- Determination of Neutral Sugars by Gas Chromatography --- p.43
Chapter 2.4.5.4 --- Uronic Acid Content --- p.44
Chapter 2.4.6 --- Uronic Acid Block Composition --- p.44
Chapter 2.4.6.1 --- "MG, MM and GG Block Determination" --- p.44
Chapter 2.4.6.2 --- M/G Ratio Determination --- p.45
Chapter 2.4.6.3 --- Phenol-Sulfuric Acid Method --- p.45
Chapter 2.5 --- Physico-Chemical Properties of Alginate --- p.46
Chapter 2.5.1 --- Viscosity --- p.46
Chapter 2.5.1.1 --- Ostwald Viscometer --- p.46
Chapter 2.5.1.2 --- Brookfield Viscometer --- p.47
Chapter 2.5.2 --- Molecular Weight --- p.47
Chapter 2.5.2.1 --- From Intrinsic Viscosity --- p.47
Chapter 2.5.2.2 --- Gel Permeation Chromatography-Laser Light Scattering (GPC-LLS) --- p.48
Chapter 2.6 --- Functional Properties of Alginate --- p.49
Chapter 2.6.1 --- Emulsifying Activity (EA) and Emulsion Stability (ES) --- p.49
Chapter 2.6.2 --- Gel Formation --- p.49
Chapter 2.6.3 --- Gel Strength and Syneresis --- p.50
Chapter 2.6.4 --- Application in Food ´ؤ Fruit Jelly --- p.52
Chapter 2.7 --- Data Analysis --- p.53
Chapter CHAPTER THREE --- RESULTS AND DISCUSSION
Chapter 3.1 --- Proximate Composition of Selected Seaweed --- p.54
Chapter 3.1.1 --- Moisture Content --- p.54
Chapter 3.1.2 --- Ash Content --- p.56
Chapter 3.1.3 --- Crude Protein Content --- p.57
Chapter 3.1.4 --- Carbohydrate Content --- p.58
Chapter 3.2 --- Chemical Composition of Alginate Extracted from Two Different Methods --- p.58
Chapter 3.2.1 --- Percentage Yield --- p.59
Chapter 3.2.2 --- Alginate Content --- p.61
Chapter 3.2.3 --- Moisture Content --- p.62
Chapter 3.2.4 --- Ash Content --- p.62
Chapter 3.2.5 --- Residual Protein Content --- p.63
Chapter 3.2.6 --- Monosaccharide Composition of Alginate --- p.63
Chapter 3.2.7 --- M/G Ratio --- p.66
Chapter 3.2.8 --- Summary --- p.69
Chapter 3.3 --- Comparative Studies of Physico-Chemical Composition of Alginate from Sargassum and Padina Species --- p.71
Chapter 3.3.1 --- Block Composition and M/G Ratio --- p.71
Chapter 3.3.2 --- Viscosity --- p.75
Chapter 3.3.2.1 --- Intrinsic Viscosity ´ؤ Capillary Viscometer --- p.75
Chapter 3.3.2.2 --- Solution Viscosity - Brookfield Viscometer --- p.79
Chapter 3.3.2.2.1 --- Effect of Temperature --- p.79
Chapter 3.3.2.2.2 --- Effect of Concentration --- p.81
Chapter 3.3.2.2.3 --- Shear Thinning and Time Independent Effect --- p.82
Chapter 3.3.3 --- Molecular Weight --- p.88
Chapter 3.3.3.1 --- From Intrinsic Viscosity --- p.88
Chapter 3.3.3.2 --- Gel Permeation Chromatograph-Laser Light Scattering (GPC-LLS) --- p.90
Chapter 3.4 --- Comparative Studies of the Functional Properties of Extracted Alginate with Commercial Alginate --- p.93
Chapter 3.4.1 --- Emulsifying Activity (EA) and Emulsifying Stability (ES) --- p.93
Chapter 3.4.2 --- Gelling Properties --- p.95
Chapter 3.4.2.1 --- Effect of Calcium Concentrations --- p.95
Chapter 3.4.2.2 --- Gel Strength and Syneresis --- p.97
Chapter 3.4.3 --- Application in Food --- p.99
Chapter CHAPTER FOUR --- CONCLUSIONS --- p.103
REFERENCES --- p.105
RELATED PUBLICATION --- p.120

Mercury (Hg) is one of the primary contaminants of concern in the Arctic marine ecosystem. Methyl Hg (MeHg) is known to biomagnify in food webs. During the International Polar Year - Circumpolar Flaw Lead study, sea ice, seawater, bottom ice algae, phytoplankton and the herbivorous copepods were collected from the Amundsen Gulf to test whether ice algae and phytoplankton assimilate Hg from their habitat, and whether Hg bioaccumulates from the seawater to the primary consumers. Sea ice algae were found to accumulate Hg primarily from the bulk bottom ice, and the sea ice algae bloom depleted Hg stored within the bottom section of the ice. Furthermore, biodilution of Hg was observed to occur in sea ice algae. Higher concentrations of Hg were also found in phytoplankton and in grazing copepods. A positive correlation between MeHg and trophic level suggests the occurrence of MeHg biomagnification even at these low trophic positions.

Bibliography: leaves 191-225.
2 v. : ill. (some col.), maps ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
The temporal dynamics of eight subtidal mixed macroalgal communities were quantified. The results were discussed in terms of the implications for sampling programs in the future and the reliability of previous work.
Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1997?

Bibliography: leaves 191-225.
2 v. : ill. (some col.), maps ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
The temporal dynamics of eight subtidal mixed macroalgal communities were quantified. The results were discussed in terms of the implications for sampling programs in the future and the reliability of previous work.
Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1997?

This study investigated the effects of nitrogen and phosphorus on the growth and ecophysiology of a number of dominant species of macroalgae at a site in Port Phillip Bay (PPB), a large shallow water marine embayment located on the central southern coast of Victoria, Australia. This thesis investigated the physiological processes (i.e. photosynthesis, growth, nutrient uptake) of three species of macroalgae, Hincksia sordida (Harvey) Clayton (Phaeophyta), Polysiphonia decipiens Montague (Rhodophyta) and Ulva sp. (Chlorophyta) in response to a range of environmental regimes.

Harmful algal blooms (HABs) which can produce a variety of marine biotoxins are a prevalent and growing risk to public safety. The aim of this research was to investigate, evaluate, develop and validate an analytical method for the detection and quantitation of five important groups of marine biotoxins in shellfish tissue. These groups included paralytic shellfish toxins (PST), amnesic shellfish toxins (AST), diarrheic shellfish toxins (DST), azaspiracids (AZA) and neurotoxic shellfish toxins (NST).

Ma Wing-chi, Joyce.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 131-148).
Abstracts in English and Chinese.
Abstract (in English) --- p.i
Abstract (in Chinese) --- p.iv
Acknowledgement --- p.vi
Contents --- p.viii
Abbreviation --- p.xii
List of Tables --- p.xiii
List of Figures --- p.xv
Chapter 1. --- Introduction --- p.1
Chapter 2. --- Literature review --- p.5
Chapter 2.1 --- Fisheries in Hong Kong --- p.5
Chapter 2.2 --- Flavor of seafood --- p.6
Chapter 2.2.1 --- Lipid-derived volatile aroma compounds --- p.7
Chapter 2.2.2 --- "Alcohols, aldehydes and ketones" --- p.8
Chapter 2.2.3 --- Enzymatic conversion of sulfur- and nitrogen-containing precursors --- p.9
Chapter 2.2.4 --- Thermally generated compounds --- p.9
Chapter 2.2.5 --- Bromophenols --- p.10
Chapter 2.2.5.1 --- General properties of bromophenols --- p.11
Chapter 2.2.5.2 --- Threshold of bromophenols --- p.14
Chapter 2.2.5.3 --- Toxicity of bromophenols --- p.17
Chapter 2.2.5.4 --- Previous studies about bromophenols --- p.19
Chapter 2.2.5.5 --- Bromophenols in aquacultured seafood --- p.20
Chapter 2.2.5.6 --- Possible dietary sources of bromophenols --- p.20
Chapter 2.2.5.7 --- Possibility of increasing bromophenol content in aquacultured fish --- p.23
Chapter 2.3 --- Criteria for selecting experimental fish model --- p.24
Chapter 3. --- Distribution of Bromophenols in selected Hong Kong seafoods --- p.27
Chapter 3.1 --- Introduction --- p.27
Chapter 3.2 --- Materials and methods --- p.28
Chapter 3.2.1 --- Sample collection and preparation --- p.28
Chapter 3.2.2 --- Simultaneous steam distillation-solvent extraction (SDE) --- p.30
Chapter 3.2.3 --- Gas chromatography / mass spectrometry (GC/MS) --- p.30
Chapter 3.2.4 --- Compound identification and quantification --- p.31
Chapter 3.2.5 --- Recoveries --- p.33
Chapter 3.2.6 --- Moisture determination --- p.34
Chapter 3.2.7 --- Statistical analysis --- p.34
Chapter 3.3 --- Results and discussion --- p.34
Chapter 3.3.1 --- Distribution of bromophenols in seafoods --- p.34
Chapter 3.3.1.1 --- Bromophenols in marine fishes --- p.49
Chapter 3.3.1.2 --- Bromophenols in mollusks --- p.49
Chapter 3.3.1.3 --- Bromophenols in crustaceans --- p.50
Chapter 3.3.2 --- Seasonal variations of TBCs --- p.51
Chapter 3.3.3 --- Bromophenols in diet contents --- p.52
Chapter 3.3.4 --- Bromophenol contents of freshwater fish --- p.53
Chapter 3.3.5 --- Relationship between the living habitats and bromophenol contents --- p.56
Chapter 3.3.6 --- Bromophenols as flavor compounds in seafoods --- p.58
Chapter 3.4 --- Conclusion --- p.59
Chapter 4. --- Distribution of Bromophenols in selected Hong Kong seaweeds --- p.61
Chapter 4.1 --- Introduction --- p.61
Chapter 4.2 --- Materials and methods --- p.62
Chapter 4.2.1 --- Sample collection and preparation --- p.62
Chapter 4.2.2 --- Simultaneous steam distillation-solvent extraction (SDE) --- p.63
Chapter 4.2.3 --- Gas chromatography / mass spectrometry (GC/MS) --- p.64
Chapter 4.2.4 --- Compound identification and quantification --- p.65
Chapter 4.2.5 --- Recoveries --- p.66
Chapter 4.2.6 --- Moisture determination --- p.67
Chapter 4.3 --- Results and discussion --- p.67
Chapter 4.3.1 --- Distribution of bromophenols in marine algae --- p.67
Chapter 4.3.2 --- Seasonal variations --- p.76
Chapter 4.3.3 --- Functions of bromophenols in marine algae --- p.79
Chapter 4.3.4 --- Marine algae as sources of bromophenols in marine environment --- p.80
Chapter 4.4 --- Conclusion --- p.81
Chapter 5. --- Enhancement of bromophenol contents in aquacultured fish by the development of bromophenol-rich fish feeds --- p.83
Chapter 5.1 --- Introduction --- p.83
Chapter 5.2 --- Materials and methods --- p.85
Chapter 5.2.1 --- Preparation of fish feeds --- p.85
Chapter 5.2.2 --- Storage conditions of fish feeds --- p.88
Chapter 5.2.3 --- Experimental animals --- p.88
Chapter 5.2.4 --- Solvent and chemicals --- p.90
Chapter 5.2.5 --- Extraction and quantification of bromophenols --- p.90
Chapter 5.2.5.1 --- Simultaneous steam distillation-solvent extraction (SDE) --- p.90
Chapter 5.2.5.2 --- Gas chromatography / mass spectrometry (GC/MS) --- p.91
Chapter 5.2.5.3 --- Compound identification and quantification --- p.92
Chapter 5.2.5.4 --- Recoveries --- p.93
Chapter 5.2.6 --- Moisture determination --- p.94
Chapter 5.2.7 --- Statistical analysis --- p.94
Chapter 5.2.8 --- Sensory test --- p.95
Chapter 5.3 --- Results and discussion --- p.96
Chapter 5.3.1 --- Bromophenol contents in wild-harvested and aquacultured fish --- p.96
Chapter 5.3.2 --- Development of bromophenol-rich fish feed --- p.99
Chapter 5.3.3 --- Effect of feeding the fish with the fish feed developed --- p.105
Chapter 5.3.4 --- Sensory evaluation on the flesh of the fish fed with different fish feeds --- p.121
Chapter 5.3.5 --- Growth of the fish fed with different fish feeds --- p.124
Chapter 5.4 --- Conclusion --- p.126
Chapter 6. --- General conclusion and significance of the study --- p.128
References --- p.131