Thesis (Ph.D.)--Murdoch University, 2005. / Thesis submitted to the Division of Science and Engineering. Bibliography: leaves 225-252.

Thesis (Ph. D.)--University of Rhode Island, 2004. / Typescript. Includes bibliographical references (leaves 161-182).

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 143-152).

Although, microalgal wastewater treatment systems represent an efficient and economical alternative to conventional processes, the use of marine microalgae to remove nutrients from wastewaters has not been extensively researched and few studies have been made in temperate and high latitude areas, where climate may limit treatment. In this study, 102 marine microalgal species, including 66 local endemic isolates from St Andrews Bay, Fife, Scotland, were screened under batch and continuous culture. Species were selected for their ability to remove high concentrations of ammonium and ortho-phosphate from primary treated sewage (diluted 1:1 with sterile seawater) while remaining dominant in culture. Abiotic removal of ammonium and ortho-phosphate at high pH was found to be low from saline media, indicating that much of the nutrient removal from the seawater:wastewater mixture was by algal uptake. Many of the best-treating species grew over a wide range of temperature (10-25 °C), and their growth was not inhibited by the low salinity of the 1:1 diluted wastewater. Seven best-treating species continuously removed >80 % ammonium and >70% ortho-phosphate when cultured in 20 litre mini-ponds (modelled on high-rate ponds) under ambient summer conditions over two weeks. These were all endemic isolates including six bacillariophyceaen isolates (of which three were strains of Phaeodactylum tricornutum), and a species of the cyanophyceaen Oscillatoria. Two isolates (Oscillatoria and an unidentified bacillariophyceaen SA91B33) with adherent properties, continuously removed 100 % of both ammonium and ortho-phosphate when tested in a corrugated raceway designed to provide a large surface area for attachment. Preliminary experiments further showed the best-treating species to be capable of removing nutrients from eel aquaculture effluent. The abilities of marine microalgal species to remove high concentrations of nutrients, remain in unialgal culture and grow over a range of environmental conditions are indicative of their potential for use in wastewater treatment systems in temperate areas.

Treatment of waste water by freshwater microalgae is rapidly becoming a popular sewage treatment practice throughout the world, but only a few studies have been made into the use of marine strains or of their potential for heavy metal removal. This study examines the heavy metal tolerance of a range of marine microalgal species and examines some of the biological processes involved in metal uptake. Initially over 350 marine microalgal species/isolates were screened for (a) growth in the presence of heavy metals (10 ppm), (b) growth in the presence of wastewater (1:1 sewage : seawater), and (c) heavy metal uptake. Of the microalgae examined, only one isolate, Tetraselmis sp. (TSAW92) was found to satisfy all of the screening conditions. Metal uptake was found to be a biphasic process, with an initial rapid saturable metabolism-independent stage followed by a slower nonsaturable metabolism-dependent stage. Using a novel filtration technique metal uptake was measured at ten second intervals. The results show that most of the metal uptake occurs within one minute after exposure. The second stage of metal uptake was found to be associated with the extracellular release of up to three copper binding proteins of ca. 28, 30, 55 kDa. Protein release was specifically induced by the presence of heavy metals and was not due to metal mediated increases in cell membrane permeability. Two practical applications of Tetraselmis sp. (TSAW92) metal uptake were investigated. First dried biomass was evaluated in a simple packed column. Second, live cells were grown on a wastewater treatment raceway (2m), upstream of a Dunaliella salina stocked nutrient removal raceway. Dried Tetraselmis sp. (TSAW92) was capable of removing copper from a 1:1 seawater : sewage solution to a final loading of 30% at an efficiency of approaching 100%. Over four weeks live TSAW92 removed 100% of the applied copper to a final loading of 37%, and, after the second stage, the raceway was found to remove 95% of the applied nitrogen and 87% of the applied phosphorus. This thesis shows that marine microalgae are capable of removing heavy metals from wastewater in vitro, on raceways, and as dried biomass. Live marine microalgae on raceways were further found to remove inorganic nutrients (nitrogen and phosphorous). In addition work is presented which suggests that copper uptake by the marine chlorophyte Tetraselmis sp. (TSAW92) is mediated through extracellular copper binding proteins.

The productivity of the large brown alga Phyllogigas grandifolius (A. & E.S. Gepp) Skottsb. has been studied over a period of 2 1⁄2 years. This alga is endemic to the Antarctic and circumpolar in distribution. Photosynthesis was measured in situ using SCUBA, Uptake of 14C-labelled sodium bicarbonate was used to obtain values for gross photosynthesis throughout the year, and by monitoring respiration at the same time using the Winkler technique a value for daily accretion could be found. The curves for daily accretion showed only one mm maximum per season, that at the deeper of the two sites occurring later than at the shallow site, as the light levels reaching the deeper algae continued to increase. Positive accretion expressed in mugC. cm-2.d-1 was observed only during the summer months. Maxima in 1974 were 70 mugC. cm-2.d-1 at the shallow site and 56 at the deep site. Respiration was low throughout the year as a result of the small annual range of water temperature (+1.5°C to -2°C). The mean respiratory rate was found to be 1.55 mugC. cm-2.h-1 Variation in the rate was observed along the length of the frond with the maximum occurring in the region of the meristem about 10cm. above the base of the frond. In situ studies of frond growth showed a complete cessation of growth during the winter months but recommenced before the departure of the sea-ice. This and day length appear to be the two main limiting factors of growth. Mean growth rate: 8.0mm. wk-1. With the growing season restricted, to 6 months, the mean productivity for that season was found to be 2.4 g C.m-2.d-1, with a photosynthetic efficiency of 14%. In the winter this efficiency drops to 1%. These figures were obtained from bomb calorimetry studies. Mannitol, the main storage product and primary respiratory substrate showed summer maxima of around 18% dry weight, falling to 2% during the winter. Due to the irregular distribution of the alga, biomass estimates are rather subjective. One of the denser 'stands' of Phyllogigas gave a figure of 0.813 kg. m-2 and a Leaf Area Index of 4.5. Other LAI values were as low as 0.0028. The mean SLA was 0.075. The net annual primary productivity was found to be 15.3 metric tons, hectare-1 year-1.

Physiological studies were made of 23 species of red seaweeds (Rhodophyta) and 2 species of green seaweeds (Chlorophyta) in Sicily and at various sites in the British Isles. In Britain, these algae formed part of an "underflora" beneath the canopy of the dominant sublittoral "kelp forest" of Laminaria hyperborea (Phaeophyta). In the Mediterranean, the algae studied formed a turf composed largely of green and red species. In Britain, a standing crop of non-laminarian species of 140g dry weight m-2 was recorded at 5m depth, and approximately half of this at 12m; the crops were about 4 and 12% respectively of the total biomass per m2. At Sicily (Ganzirri, Straits of Messina) a maximum crop of 1360g (dry weight) m-2 was recorded at 15m depth. Radioactive tracer (14C) and dissolved oxygen (Winkler) techniq.ues were developed for use underwater to depths of 60m. Photosynthetic rates measured under agitated incubation conditions were approximately twice the values obtained under static conditions. Rates of photosynthesis measured using the 14C technique were generally high in shallow algae incubated in situ in Britain, e.g. 20 mug C cm-2 h-1 for Porphyra umbilicalis at Om depth; 11 mug C cm-2 h-1 for Rhodymenia palmata, 3m depth. Deeper algae had lower in situ rates, e.g. Delesseria sanguinea, 3.1 mugC cm-2 h-1 and Phycodrys rubens, 1.8 mugC cm-2 h-1, both at 18m depth. At Ganzirri, using the C method, Porphyra umbilicalis attained a rate of 18 mugC cm-2 h-1 at 4.5m and Pseudolithophyllum expansum 4.7 gC cm-2 h-1 at 60m depth. Rates of photosynthesis were strongly reduced by the reduction of irradiance by the water column. Reduction of rates was even more strongly influenced by self-shading in algal stands, Dilsea reaching a photosynthetic efficiency of 8% beneath a L.hyperborea canopy at 4m depth. In general, deep-growing algae were found to be "shade-adapted" (low maximal photosynthetic rates, high-efficiency at low irradiance) and shallow-growing algae were "sun-adapted" but there were notable exceptions. Adaptation occurred within single species. At the deep sites, green algae had photosynthetic rates as high as, or higher than, coexisting red species, suggesting that the red algae had no simple intrinsic photosynthetic advantage conferred by their accessory pigments. Deep specimens of red species exhibited photoinhibition of photosynthesis and photodestruction of pigments when incubated in surface solar irradiance of N 40 J cm-2 PAR. This was noted in such species as Delesseria sanguinea, Phycodrys rubens, Peyssonelia sp., Pseudolithophyllum expansum. Few species studied were below 24-hour compensation point during the summer months and high irradiances of the studies. Few of the deeper algae, however, were operating at or above saturation for any significant length of time. They were thus generally operating at their own maximal efficiencies for most of the time.

Forty clones of Gonium pectorale M'uller were crossed in all combinations at 20°C, and the resultant zygotes examined to determine the degree of sexual compatibility within a single population. Clones isolated from the same site but in different years were incompatible, indicating a lack of gene flow between them. Two distinct groups were found within 31 clones isolated from a single mud sample, and all the clones in one were incompatible with all those in the other. However, members of both groups were compatible with those in a third group. The existence of at least two complementary pairs of mating types within a single G. pectorale population, sensu Stein (1958b), is considered in the context of other sexual compatibility results, and is proposed as a reason for the occasional inability to obtain opposite mating types from a mud sample from which only a few clones have been isolated. / Science, Faculty of / Botany, Department of / Graduate

Graduation date: 2001

No description available.