The study has attempted to characterise the physicochemical limnology and distribution of algal flora of two salt lake systems in Western Australia, one from the coastal Esperance region and the other from the inland Kambalda region. Climatic conditions, water regimes and physicochemistry were found to differ markedly between the two lake systems and a total of 171 algal taxa, representing five divisions, were recorded. Of these, 82 were members of Bacillariophyta, 48 of Cyanophyta, 33 of Chlorophyta, two of Euglenophyta and six of Dinophyta. The physical limnology of salt lakes in the Esperance region was seasonally variable, defined by climatic conditions. As such, the lakes investigated in the region exhibited a stable cycle of filling during winter and spring, and drying out in summer. Four of the lakes in the region could be classified as near-permanent, and one as seasonal on the basis of predictability and duration of filling. Seasonal fluctuations in water depth resulted in fluctuations in salinity levels. Salinity levels ranged from subsaline to hypersaline, and all the lakes in the region were alkaline. In addition, the lakes were well mixed in terms of oxygen and temperature, and were impacted by eutrophication from their catchments. They were either mesotrophic or eutrophic with respect to both nitrogen and phosphorus. In geological terms, lakes in the Esperance region were separated only recently from the ocean, and two lakes retain a connection with marine waters, one through a creek during years of high rainfall and one through hydrological interactions with groundwater of marine origin. In general, the algal communities of lakes in the Esperance region were similar to those of other Australian coastal salt lakes. / Diatoms and cyanobacteria were dominant in all lakes except the most eutrophic, Lake Warden, in which benthic green algae were most abundant. All algal species recorded were known for their wide geographic distribution and their distribution in Australian coastal waters. Characteristically coastal diatom species included Achnanthes brevipes, Achnanthes coarctata, Achnanthes lanceolata var. dubia, Achnanthidium cruciculum, Campylodiscus clypeus, Cyclotella atomus, Cyclotella meneghiniana, Cyclotella striata, Mastogloia elliptica, Mastoglia pumila, Nitzschia punctata and Thalassiosira weissflogii. The inland salt lakes of the Kambalda region form part of an extensive palaeodrainage system, and were much less predictable in terms water regime than lakes in Esperance. Water depth was determined by seasonal variability in rainfall and evaporation, and by summer cyclonic rainfall events that were unreliable from year to year. In addition, rainfall varied spatially within the region. As such, most lakes were classified as intermittent. Two lakes in the region were not classified on the basis of water regime as they were too highly impacted by mining activities including water diversion and impoundment, water extraction and discharge of groundwater. Salinity varied in accordance with drying and filling cycles in the lakes except the most hypersaline as the volume of water received during rainfall events was insufficient to dilute the extensive surface salt crusts they each supported when dry. Salinities recorded in the region ranged from subsaline to hypersaline, and ionic compositions exhibited the same spectrum as seawater. / Calcium levels were significantly higher than in lakes from the Esperance region due to weathering of calcium rich sediments, and pH ranged from weakly acidic in the most hypersaline lakes to alkaline in the least saline lakes. All were well mixed in terms of oxygen and temperature. Kambalda salt lakes support distinctive algal communities dominated by diatoms and cyanobacteria that are adapted to intermittent water regimes, extended periods of desiccation and variable salinity. Not surprisingly then, none of the algal taxa recorded from the region were regionally restricted, all noted previously in the literature to have wide geographic distributions, and to be tolerant of a range of physicochemical conditions. Canonical correspondence analysis showed that, of the physicochemical parameters that were investigated in this study, both salinity and pH interacted in determining algal community structure. Both of these attributes were correlated with water depth, which varied according to climatic conditions in a seasonal drying and filling cycle. The general relationship between species richness and pH and salinity, and species diversity and pH and salinity was simple and linear; with increasing pH and salinity, species diversity and species richness decreased. What was less simple, and non-linear, was the nature of the relationship between species richness and diversity and salinity within more narrowly defined ranges of salinity. As salinity increased from <1ppt to 30ppt there was a dramatic reduction in species richness and diversity, then, as salinity increased from 30ppt to 100ppt the rate of decrease slowed. Between 100ppt and 250ppt there was almost no relationship between salinity and species richness and species diversity, but after 250ppt both species diversity and species richness declined markedly.

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).

Eutrophication is a global problem affecting many inland and estuarine waters. Many wetlands on the Swan Coast Plain, in Western Australia, have undergone increasing nutrient enrichment since European settlement of the region in the 1850’s. Problems such as algal blooms and nuisance swarms of non-biting midges (Diptera; Chironomidae) are the consequence of nutrient enrichment in many of these wetlands. The restoration of these degraded wetlands, especially with respect to reducing nutrient enrichment, requires a range of comprehensive and effective techniques including catchment management, diversion or treatment of surface inputs and treatment of enriched sediments. Nitrogen and phosphorus, especially phosphorus, are not the only factors controlling algal biomass in water bodies, but they are the only elements that can be removed efficiently and economically. Internal P cycling from wetland sediments can initiate and sustain eutrophication and related algal blooms and nuisance midge problems even after external sources are diverted or reduced. The aim of this study was to identify an effective material to reduce sediment phosphorus release and thereby the phosphorus concentration of the water column. It was also important to determine the impact of the selected amendment material on phytoplankton and larval midge (chironomid) communities. A range of experiments at increasing scales, from bench-top, to microcosm to outdoor mesocosm experiments were designed to test three hypotheses: 1) Materials which have a high P sorption capacity, over a wide range of P solution concentrations, and low P release rate, are potentially suitable agents to reduce P in wetlands with enriched sediments by inactivating sediment P; 2) A reduction in the abundance of cyanobacteria caused by increasing the N:P ratio of an aquatic ecosystem results in a reduction in the density of nuisance species of Chironomidae. 3) Successful amendment of enriched sediments reduces P in the water column thereby reducing the total phytoplankton biomass and the related density of nuisance species of Chironomidae. The adsorption and desorption experiments were carried out under a range of pH values and P concentrations, with a number of materials including fly ash, red mud, precipitated calcium carbonate, crushed limestone and lime to determine the maximum adsorption capacity and affinity of these materials. A rang of P concentrations (0-1000 µg/L) simulated the P concentration of the water column in a range of wetlands of differing trophic status. Poor fits to the Langmuir equation occurred with both red mud and fly ash due to their high P content. A good fit occurred with lime, with a high P removal rate (90%-96%) over the same range. Fly ash and red mud were eliminated from further investigation due to the possibility that they might release phosphorus rather than absorb when P concentrations in surrounding environment were less than 300 µg/L or 200 µg/L respectively (concentrations which can occur in eutrophic systems). Among the three lime-based, redox-insensitive materials tested in the second mesocosm experiments, precipitated calcium carbonate (PCC) possessed the highest maximum adsorption capacity and lowest desorption rate under a range of pH values (6.2, 7.2 and 10) and P concentrations (0-12 000 µg/L), followed by crushed limestone and lime. The different maximum absorption capacities of the three materials appears to be mainly attributed to their particle size (surface area). Lime was chosen as the amendment material for further investigation because it was the only one of the three available in sufficient quantities within the timeframe of this study. Microcosm experiments showed that lime was effective in reducing sediment P release from intact sediment cores, and the ratio of TN:TP in the treatment cores increased over time compared to the control cores (in which TN: TP decreased slightly). In the first mesocosm experiment a significantly higher density of larval midges was found in the treatments than in the controls. The treatments were aimed to increase N:P ratio in the systems to reduce cyanobacteria and, subsequently, larval midge densities. However even though cyanobacteria were eliminated from the treatments, the nitrogen addition appeared to result in higher phytoplankton biomass overall, which fuelled an increase in larval midge densities. In the second mesocosm experiment, the addition of lime to enriched sediments resulted in a reduction in P in the water column. This reduction was accompanied by a reduction in total phytoplankton biomass, the absence of cyanobacteria, and a less abundant and more species - diverse chironomid fauna in the treatment mesocosms. Sediment P fractionation undertaken for both the microcosm and mesocosm experiments showed that most of the phosphorus adsorbed by lime was in the labile fraction (NH3Cl extractable P and NaOH extractable P). Phosphorus in the HCl extractable fraction was also found to be higher in the treatments due to the presence of inert mineral P in the lime than the formation of new hydroxyapatite from adsorbed P. The two mesocosm experiments suggested that larval midges were non-selective feeders, responding to total phytoplankton biomass, rather than the presence of cyanobacteria. Dissolved oxygen and predation also influenced larval midge densities. In summary, although lime appeared to be a useful material for reducing P release from enriched sediments under controlled laboratory conditions, the effect under field conditions was not as definitive. Further work is required to more fully determine the conditions under which sediment remediation may be used as a means of controlling sediment P release and associated high densities of larval chironomids.

"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

Le chenal algal à haut rendement (CAHR) est un procédé dépuration qui offre, en plus de lépuration des ces eaux usées, la production dune biomasse valorisable. Dans ce contexte, notre travail de thèse a porté essentiellement sur la gestion, la récupération et la valorisation de cette biomasse. Ainsi, dans un premier temps, nos travaux de recherche ont porté : dune part, sur le suivi par la technique de fluorescence variable de lactivité photosynthétique des microalgues au cours du processus épuratoire ; dautre part, sur lestimation de la biomasse par la technique de microscopie à épifluorescence et danalyse dimages. Les résultats obtenus ont prouvé lefficacité de ces deux techniques. Pour ce qui est de la récupération de la biomasse du chenal algal, on a dabord procédé, dans un premier temps, à déterminer les conditions dautofloculation des microalgues du CAHR ; par la suite on a effectué des essais de préconcentration de leffluent du chenal algal par filtration membranaire. Les résultats obtenus ont montré que cette technique est efficace quant à la récupération de la biomasse du CAHR. Les essais de décantation, centrifugation et flottation, réalisés sur le concentrat obtenu par filtration membranaire, ont montré, quant à eux, quil est préférable dutiliser la décantation comme technique pour récupérer la biomasse préconcentrée par filtration membranaire. Après la récupération de la biomasse du chenal algal, on a procédé à sa caractérisation en vue dévaluer son contenu en protéines, lipides, polysaccharides et pigments. Les résultats obtenus ont montré que la biomasse est très riche en pigments chlorophylliens et caroténoïdes ; par conséquent sa valorisation a été orientée vers la voie dextraction du Biogreen. Létude de faisabilité de la technique dextraction envisagée a été effectuée dans le cas du chenal algal en vraie grandeur de la station Essada de Marrakech. Le calcul économique a dégagé une marge bénéficiaire importante, ce qui pourrait, par la suite, contribuer à assurer léquilibre financier du chenal algal à haut rendement.

Gradients of physical disturbance are central to theories of community organization yet rarely are studies performed in which physical factors are experimentally manipulated. Pothole tidepool algal communities exhibit distinct zonation patterns from top to bottom that result from scouring by rocks and other debris in the pools. Scouring is easily manipulated by removing or adding rocks to tidepools. Thus, the gradient of physical disturbance potentially causing community patterns can be manipulated to test theories of community organization. I documented the distribution pattern of algae inhabiting pothole tidepools and measured a number of physical factors which were hypothesized to be responsible for the observed zonation patterns. Then, I experimentally evaluated the roles of physical disturbance, herbivory, and competition in these tidepool communities. I found that scouring by rocks was primarily responsible for the observed zonation patterns in pothole tidepools. However, not all pools are potholes. Evaluation of the physical properties effecting the cobble-retaining ability of tidepools enabled prediction over a broad geographic range of pools likely to have cobbles and thus show typical pothole algal zonation patterns. Coralline algae (Rhodophyta, Corallinaceae) are a dominant feature of tidepools as well as many low intertidal and subtidal habitats. I evaluated the relative resistance of coralline algae (both articulated and crustose forms) and other common tidepool algae to scouring by rocks. Coralline crusts were highly resistant to scouring while articulated coralline algae are very susceptible to scouring. Erect fleshy algal species showed intermediate resistance to scouring. This corresponds well to observed algal zonation patterns in intertidal potholes. Based on this information, I proposed that wave-induced scouring may have been the selective force for the initial incorporation of calcium carbonate into algal thalli. / Graduation date: 1992

In this study, I examined the influence of hydrological seasonality on spatiotemporal variation of algal biomass and shrimp abundance on sandbanks of the Cinaruco River in southwestern Venezuela. Seasonal variations of abiotic and biotic variables in the Cinaruco were driven by the hydrological regime. During the highwater periods, river sites in the main channel and lagoon sites were similar in water physicochemical variables and algal biomass. In contrast, physicochemical variables and algal biomass differed between river and lagoon sites during the low-water period. The absence of flow in lagoons and consistently low algal biomass on river sandbanks were the most important features of the spatial variability between main-channel and lagoon sandbanks during low-water phases. Benthic algal biomass was highly uniform at small spatial scales and significantly heterogeneous at large spatial scales. In the second major part of this dissertation, I found a relatively species-rich shrimp assemblage with seven species inhabiting the sandbanks of the Cinaruco. I also observed clear patterns of temporal and spatial variation in shrimp abundance on the Cinaruco sandbanks. Abundance of shrimp on the sandbanks presented remarkable diel variation, showing almost exclusive use of this habitat at nights. Seasonally, shrimp were more abundant during rising- and falling-water periods, when rapid changes of environmental conditions occur. Shrimp abundance was high on those sandbanks with absence of troughs and presence of submerged vegetation. These environmental features presumably promote colonization/establishment and survival/persistence of shrimp in the sandbanks. In a patch-dynamic view of communities, a mobility control model seems to apply to shrimp of the sandbanks in the Cinaruco during the period of rapid changes in hydrology and habitat structure. During low-water periods, when habitat structure of sandbanks is relatively constant, low shrimp abundance appears to be heavily controlled by high fish predation. The annual flood regime of the Cinaruco, which drives the concentrations of dissolved materials, affects material interchanges between aquatic and terrestrial systems, and modifies aquatic habitat structural complexity, is responsible for creating strong patterns of seasonal and spatial variation in benthic algal crops and shrimp abundance on the sandbanks of this large floodplain river.

Thesis (M.S.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. xv-130).

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