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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.

This thesis has attempted to describe some of the distribution patterns of submerged aquatic macrophytes in Scottish lochs. Effort has been directed towards prescribing a precise lochs. Effort has been directed towards prescribing a precise meaning to productivity with respect to these plants to its measurement, and to investigating presible influencing factors. Using aqualung diving techniques, biomass estimates have been made in several lochs. These results have been viewed in two ways, (a) qualitatively and (b) quantitatively. Qualitative It has been that, in any one loch, there is a zonation of species with depth of water. Generally, Littorella uniflora/Lobelia dortmanna communities were dominant in the shallower water (up to one metre), while otamogeton species occupied the deeper areas (up to seven metres). Of the substrate variables investigated, no parameters have been shown to be causally correlated with the distribution of such factors was complicated by a high degree of variance in the biomass estimates of vegetation on fairly uniform substrates. Distribution patterns of species between lochs have also been noted. The members of the Characeas were only found in the limestone lochs of high pH and alkalinity, while Lobelia dortmanna and Isoetes lacustris were confined to the more base-poor waters. Litorella uniflora was found in all the Iochs studied. Only two species of broad-leaved, sub-merged pondwecds were found in the limestone lochs but, while these were not restricted to such habitats, other species of the genus Potamogeton were. No one factor has been shown to underlie this distribution pattern though, in the case of the Characeae, it would appear that the high alkalinity of the water is related to the predominance of some members of this family in the limestone lochs, where they can produce their calcium carbonate exoskeletons. It is also possible that the low concentration of phosphorus in the limestone waters, shown by others to be a maximum factor in the growth of the Characase, is also important, while the general low nutrient concentrations may exclude other species from these areas.

Climate change has a profound impact on the phenology and abundance of plankton in the NE Atlantic and North Sea. There is concern that harmful algal bloom (HAB) species may increase, accompanied by negative socio-economic impacts, including threats to human health and marine harvesting. We reviewed historical major UK outbreaks of poisoning and attempted to examine the epidemiology on a finer scale by linkage of hospital admissions, GP and pathology records. As expected the incidence of shellfish poisonings was very low but accurate identification of poisoning was generally unreliable. The current UK shellfish monitoring programme is the key indicator for monitoring trends in the risk of human exposure. Using the Continuous Plankton Recorder (CPR) survey, we mapped spatial and temporal trends of various phytoplankton, including HAB species, and zooplankton (Tintinnids and Calanus). We found fundamental shifts in the relative abundance of diatoms versus dinoflagellates, with a dramatic dinoflagellate decline in recent years. Northward shifts in abundance were found for some Tintinnid and Calanus taxa. Using criteria of statistical causality, these changes were linked to climate, in particular sea surface temperature and increasingly windy conditions in the summer, with a notable non-linear interaction between these factors. Focusing on Calanus, we showed the strength of statistical links between abundance and climate variables can wax and wane as the time series lengthens. We found tentative evidence for adaptation of Calanus to climate change, but not at a level that could reverse overall long-term patterns. Links with climate are often argued to be proxies for unobserved mechanisms that determine species abundance, such as stratification. We developed a new stratification index, covering the whole NE Atlantic from 1970 to 2009. We propose that this has wide applicability in marine climate change studies. Throughout, our work demonstrates the importance of consistent long-term ecological survey data.

The purpose of this study was to examine the sequence of changes in the gross morphology and toxicity of the raphidophyte alga Heterosigma akashiwo in the context of blooms of this species in the Strait of Georgia, British Columbia. Field work focused on this alga’s 1989 fish-killing bloom. That bloom was extensive, with discolouration of the water extending from Jervis Inlet through Malaspina Strait into the Strait of Georgia, and south to Cypress Island in Washington State. Excystment events on Spanish Banks in Vancouver harbour preceded population development in the Strait of Georgia during July and August but toxicity was only noted in the last two days of August and through September. Fish kills occurred near Cypress Island, and in Jervis Inlet and the contiguous waters of Agamemnon channel. These locations represented the geographic extremes of the discoloured waters. In Malaspina Strait and Jervis Inlet, information was collected on water column structure, macronutrient concentrations, and the distribution of algae and fish mortalities. Fish mortalities were coincident with the first sighting of waters discoloured with Heterosigma akashiwo in Agamemnon Channel and Jervis Inlet. The alga appeared to be transported to the areas by currents. Algal concentrations were higher at the Malaspina Strait end of a transect into Jervis Inlet and during flood rather than ebb tides. The water column in Malaspina Strait and Jervis Inlet was stratified and both inorganic nitrogen and phosphorus in surfece waters were low enough to limit growth of H. akashiwo. Though this alga can migrate vertically to obtain nutrients at depth, there was no evidence of migration during this toxic event. Termination of the bloom was associated with a weakening of the water column stratification and the reappearance of non-limiting concentrations of nitrogen in the surface waters. Work in culture demonstrated that there was a sequence of reproducible changes in cell size and shape that improved uptake when nutrients were at the concentrations seen in the Strait at the start of the toxic bloom. These changes involved reduction in cell volume by a factor of between 2- and 4-fold and cells changing from rounded, almost football-shaped cells (oblate spheroids), to plate-like (prolate spheroids). Mathematical modeling suggests that the volume changes could improve nutrient uptake by a factor of 21 to 38%. The changes in shape could improve nutrient uptake dynamics by a further 7.5%. Depending on the nutrient history of the population, changes in cell shape could continue beyond the plate-like form with significant portions of the algal population developing surface protuberances when adequate nutrients and energy were available to the population. The elaboration of surface processes could further improve uptake dynamics. A numerical model to describe these shapes was not available so the degree of improvement could not be quantified. As cells reach the end of their life cycle in culture, they revert to the oblate spheroid form and, if no new nutrients are added, will form resting cysts. However, cyst formation can also be triggered earlier in the life cycle by the addition of nutrients. This may benefit the species by ensuring that cells form cysts in shallow waters where spring temperatures are adequate to fecilitate excystment of cells. In addition to changes in shape. Heterosigma akashiwo cells produce a toxic agent which can suppress growth of nutrient competitors and kill predators, or make the algae unpalatable. Production of those toxins begins and declines immediately prior to decline in population numbers. Toxic effects of the alga can be caused to disappear at any time by the addition of nutrients. Similar to the differentiation of cell shape, the level of toxicity expressed by the cells appears to be correlated with the nutrient history of the population. Cells grown in higher nutrient concentrations appear to be more toxic; however, the population need not have high numbers of cells with processes to be toxic. Heterosigma akashiwo would appear to have adaptations which enhance its ability to compete and survive in the nutrient-limited waters of late summer. The adaptions include both changes in gross morphology of the cells and in the production of toxins which reduce the effects of competition and predation. Population growth and formation of concentrations of the alga capable of discolouring the water can be independent of the occurrence of toxicity. Lack of vertical migration and a protracted period of a stable, stratified water column with depleted nutrients appear to be critical to the genesis of toxicity in wild populations. / Graduate

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