The Sundays Estuary is permanently open to the sea and has been described as channel-like along its entire length with a narrow intertidal area (mostly less than 5 - 6 m in width). The estuary experiences regular freshwater inflow with large supplies of nutrients, derived from the Orange River transfer scheme and agricultural return flow. In particular, nitrate concentrations are high as a result of fertilisers used in the Sundays River catchment area. The objectives of this study were to measure microalgal biomass and community composition and relate to flow, water quality and other environmental variables. Surveys in August 2006, March 2007, February, June and August 2008 showed that salinity less than 10 percent mostly occurred from 12.5 km from the mouth and this was also where the highest water column chlorophyll a (>20 μg l-1) was found. Different groups of microalgae formed phytoplankton blooms for the different sampling sessions, which were correlated with high chlorophyll a. These included blooms of green algae (August 2006), flagellates (March 2007), dinoflagellates (June 2008) and diatom species (February and August 2008). The dominant diatom (Cyclotella atomus) indicated nutrient-rich conditions. Green algae and diatoms were associated with low salinity water in the upper reaches of the estuary. Flagellates were dominant throughout the estuary particularly when nutrients were low, whereas the dinoflagellate bloom in June 2008 was correlated with high ammonium and pH. Maximum benthic chlorophyll a was found at 12.5 km from the mouth in February, June and August 2008 and was correlated with high sediment organic and moisture content. Benthic diatoms were associated with high temperature whereas some species in June 2008 were associated with high ammonium concentrations. The middle reaches of the estuary characterise a zone of deposition rather than suspension which would favour benthic diatom colonization. Phytoplankton cells settling out on the sediments may account for the high benthic chlorophyll a because maximum water column chlorophyll a was also found in the REI zone (where salinity is less than 10 percent and where high biological activity occurs) in the Sundays Estuary. The estuary was sampled over five consecutive weeks from March to April 2009 to identify environmental factors that support different microalgal bloom species. Phytoplankton blooms, defined as chlorophyll a greater than 20 μg l-1, were found during Weeks 1, 4 and 5 from the middle to the upper reaches of the estuary. Diatom species (Cylindrotheca closterium, Cyclotella atomus and Cyclostephanus dubius) occurred in bloom concentrations during these weeks. These diatom species are cosmopolitan and indicate brackish nutrient-rich water. Flagellates were the dominant group in Weeks 2 to 4, but positive correlations with chlorophyll a were found during Weeks 1 and 2. During the first week of this study the conditions were warm and calm (measured as temperature and wind speed) and there was a well developed bloom (38 μg l-1). There was a strong cold front from 17 to 19 March, which mixed the water column resulting in the decrease of the chlorophyll a levels (<20 μg l-1) and the bloom collapsed during Weeks 2 and 3. However, in Weeks 4 and 5 conditions were again calm and warmer, which appeared to stimulate the phytoplankton bloom. Nanoplankton (2.7 - 20 μm) was dominant during each week sampled and contributed a considerable amount (55 - 79 percent) to the phytoplankton biomass. Once again subtidal benthic chlorophyll a and water column chlorophyll a were highest 12.5 km from the mouth. Deposition of phytoplankton cells from the water column was evident in the benthic samples. The study showed that the Sundays Estuary is eutrophic and characterised by microalgal blooms consisting of different phytoplankton groups.

Harmful cyanobacterial blooms have been a growing concern as global climate change and eutrophication of lakes, rivers, and oceans continually push conditions to favor cyanobacteria over other phytoplankton. Two studies were conducted assessing the impacts of hyper-eutrophication on phytoplankton communities, and phosphorous saturation in the sediments. Excess nutrients available to phytoplankton resulted in dominant cyanobacteria, and predictability of growth, by nutrient limitation, becoming drastically diminished. Sediments were observed to be fully phosphorus saturated, preventing the sequestration of excess phosphorus, and providing a consistent source of phosphorus throughout each season. Extreme saturation of nutrients reduces the predictability of systems and perpetuates the cycles of nutrient release, fueled by the growth and decay of harmful cyanobacterial blooms.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 201-227).

Thesis (Ph. D.)--University of California, Los Angeles, 2003. / Vita. Includes bibliographical references.

Eutrophication caused by nutrient loads from human activities is considered as one of the most serious environmental threats to the Baltic Sea. Due to climate change, cyanobacterial blooms are expected to increase in the future. This could affect people’s utility of beach recreation negatively in countries surrounding the Baltic. Based on a web survey carried out in south-eastern Sweden, public’s reactions and attitudes to cyanobacterial blooms are analysed. Possible economic impact on Gotland of more widespread blooms are estimated, and public demand for better information is evaluated. The result shows that 30% of the respondents from south-eastern Sweden would consider cancelling their plans of travelling to Gotland with knowledge about forthcoming algal blooms around the island. Determinants of tourists’ tendency to cancel their travel arrangements are earlier negative experiences of algal blooms and concerns regarding their pets’ bathing. The annual local economic loss for Gotland’s tourism industry is estimated to between 15 and 221 million SEK. The median willingness to pay for a mobile application which provides one-day forecasts of algal blooms is 25 SEK on Gotland and 20 SEK in southeastern Sweden. Boat owners, people who visit beaches often and those who travel to Gotland frequently, are more likely to pay for the mobile application. People who think algal blooms are natural show less demand for information.

The small dinoflagellate Azadinium spinosum produces azaspiracid (AZA) toxins which can contaminate filter feeding shellfish to dangerous levels. Toxin-contaminated shellfish flesh, when consumed by humans, can cause acute intense illness and chronic health issues. Shellfish biotoxins are monitored in Scottish shellfish by Food Standards Scotland (FSS), and the concurrent monitoring of harmful phytoplankton in the water column acts as an important early warning system of future shellfish toxin contaminations. Since A. spinosum is very small (12-16 μm long) it is difficult to identify using a light microscope, therefore molecular techniques have been developed to detect species-specific environmental DNA from phytoplankton samples. In this thesis the application and verification of quantitative real time polymerase chain reaction (qPCR) is discussed in detail and documents its first use in Scottish waters to survey A. spinosum abundance and seasonality. The limit of detection of the method was found to be 2000 ±5600 cells L-1, however it is unclear whether this is adequate for regulatory monitoring because it is not yet understood how cell density in the water column relates to AZA shellfish toxicity. The qPCR probe and primer sequences were also found to be too specific to detect all strains of the A. spinosum species, as new strains have been isolated since their development. This is a significant hindrance to the application of the tool for monitoring which will need to be addressed in the future through the isolation of local A. spinosum strains. Over a year long sampling period, A. spinosum was detected only twice (maximum cell density of 2545 ±5600 cells L-1, August 2014) off the Shetland Islands. The seasonality of the species in Scottish waters could not be assessed with so little data, however other observed harmful species of importance to shellfish regulatory monitoring are discussed; of particular note an unusual bloom of Dinophysis acuta as its association with a temperature front at the mouth of Loch Fyne. This thesis critiques the use of this qPCR technique for A. spinosum detection at high-throughput. The issues which have been highlighted do not prevent its future use by FSS, but highlight specific areas of development which need addressed before national monitoring can occur.

Phytoplankton succession and abundance in estuaries is known to be influenced by the relative strengths of various seasonally changing physical and chemical factors. Previous studies of Swan River Estuary phytoplankton biomass and composition have identified salinity, temperature, rainfall and nutrients as the most important controlling factors. These conclusions are generally based on analysis of data from river length transects and depth integrated day-time sampling. They describe influences ,affecting whole system phytoplankton abundance and succession. Many of the typical seasonal bloom that develop are ephemeral and only extend over relatively small areas. The focus of this study is a single site, Ron Courtney Island, considered typical of the upper estuary region. This region of the estuary was chosen as representative of the section of river most influenced by allochthonous nutrient input. It has been the region of most frequent and intense algal blooms over the past decade. The factors, physical, biological or physiological, that have the greatest influence on controlling phytoplankton biomass under various ambient conditions for this system are determined. While previous studies have recognised the importance of nitrogen to phytoplankton growth in the Swan River Estuary, they have focused on NO;, with only anecdotal reference to the importance of the alternative nitrogen source, NH4+. This is the first study to explore the influence of different nitrogen source fluxes on phytoplankton biomass in the upper Swan River Estuary. The roles of physiological adaptation to, and preferences for, 'new' (NO,), recycled (NH4+) and organic (urea) nitrogen sources in relation to ambient nutrient levels are explored. / Specific uptake rates (v), normalised to chlorophyll a, for NO;, NH4+ and urea were 0.2 ± 0.04 - 1831.1 ± 779.19, 0.5 ± 0.26 - 1731.6 ± 346.67 and 3.0 ± 0.60 - 2241.2 ± 252.56 ng N μg Chla-1 respectively. Urea concentration (14.8 - 117.7 μg urea-N 1-1) remained relatively constant over the 12 month study period. Measured ambient specific uptake rates for urea represent between 27.5% and 40.4% of total N uptake over the annual period February 1998 -January 1999. Seasonal nitrate uptake over the same period constituted only 11.3% (±10.77%, n=12) to 24.4% (± 13.02%, n=12) with the highest percentage during winter, when nitrate levels are elevated. It is suggested that urea provides a nutrient intermediary over the spring - summer period during transition from autotrophic to heterotrophic dominated communities. Grazing ,and nitrogen recycling are intricately connected by simultaneously providing top-down biomass control and bottom-up nutrient supply. Zooplankton (> 44 μm) grazing has been shown to reduce up to 40% of phytoplankton standing stock at times. Microheterotrophs (<300 pm) can reduce phytoplankton biomass production by up to 100% (potential production grazed, 11.1% day' - 99.6 % day-1) over an annual cycle. This correlated to mean seasonal day-time grazing loss of 80.47 ± 3.5 ngN μg Chla-1 in surface waters and 20.17 ± 9.7 ngN μg Chla-1 at depth (4.5m). Night time grazing for surface and bottom depths resulted in similar nitrogen loss rates (13.03 ± 4.84 ngN μg Chla-1). / Uptake rates for nitrate (r2 0.501) and urea (r2 0.512), doing with temperature (r2 0.605) were shown to have the greatest influence on phytoplankton distribution over depth and time. This research emphasises the need for more detailed investigations into the physiology of nutrient uptake and the effects of nutrient fluxes on phytoplankton biomass and distribution. Further research into the roles of organic nitrogen and pico and nanoplankton in this system is recommended.

This thesis investigates nutrient contribution to six hyper-eutrophic lakes located within close proximity of each other on the Swan Coastal Plain and 20 kilometres south of the Perth Central Business District, Western Australia. The lakes are located within a mixed land use setting and are under the management of a number of state and local government departments and organisations. These are a number of other lakes on the Swan Coastal Plain for which the majority are less than 3 metres in depth and considered as an expression of the groundwater as their base is below the regional groundwater table throughout most of the year. The limited amount of water quality data available for these six lakes and the surface water and groundwater flowing into them has restricted a thorough understanding of the processes influencing the water quality of the lakes. Various private and public companies and organisations have undertaken studies on some of the individual wetlands and there is a wide difference in scientific opinion as to the major source of the nutrients to those wetlands. These previous studies failed to consider regional surface water and groundwater effects on the nutrient fluxes and they predominantly only investigated single wetland systems. This study attempts for the first time to investigate the regional contribution of nutrients to this system of wetlands existing on the Swan Coastal plain. As such, it also includes new research on the nutrient contribution to some of the remaining wetlands. The research findings indicate that the lake sediments represent a considerable store of nutrients (nitrogen and phosphorus). These sediments in turn control the nutrient status of the lake's water column. Surface water is found to contribute on an event-basis load of nutrients to the lakes whilst the groundwater surprisingly appears to contribute a comparatively low input of nutrients but governs the water depth. Analysis of the regional groundwater shows efficient denitrifying abilities as a result of denitrifying bacteria and the transport is localised. Management recommendations for the remediation of the social and environmental value of the lakes include treatment of the lake’s sediments via chemical bonding or atmospheric oxidation; utilising the regional groundwater’s denitrifying abilities to ‘treat’ the surface water via infiltration basins; and investigating the merits of managed or artificial aquifer recharge (MAR).

"April 2004" / Bibliography: p. 285-299. / xxviii, 299p : ill., map ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Artificial neural networks (ANNs), trained to make short term forecasts of algal blooms in lakes and rivers, are potentially useful decision making tools for the operational management of eutrophication. This thesis addresses the question of whether a standardised, gemeric ANN model representation can be developed to achieve this goal. It is argued that four requirements need to be addressed: i) compatibility of models with existing water quality monitoring regimes, ii) stability and repeatability of training outcomes, iii) realistic and meaningful estimates of model performance, and iv) explanation of predictions. / Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : [55]-[60]).