Thesis (Ph.D.)--Murdoch University, 2001. / Thesis submitted to the Division of Science and Engineering. Bibliography: leaves 201-228.

In recent years, there has been increased interest in alternative and innovative technologies which are used in the treatment of wastewaters, with the aim of developing efficient systems which are low-cost and lowmaintenance. However, greywater reuse from domestic houses appears to have received very little attention and the role of indigenous wetland plants, especially submergents, in contributing to nutrient reduction in wastewater is largely unknown. Species of Triglochin, commonly known as water ribbons, are fast growing submergent macrophytes. In Western Australia, Triglochin huegelii is mainly a submergent plant but as water recedes, the leaves become emergent. Triglochin huegelii can tolerate a range of water regimes and high nutrient concentrations, and this is useful in wastewater treatment applications. The aims of this present study were to examine the use of Triglochin huegelii for domestic greywater treatment, to compare the effectiveness of this plant with other better known, and more frequently used, emergent macrophytes, and to investigate why Triglochin huegelii is so successful in nutrient accumulation. A series of investigations using Triglochin huegelii in greywater treatment experiments showed that Triglochin has consistently removed more nitrogen and phosphorus, in all parts of the plant - leaves, tubers and roots, than most other indigenous emergent macrophyte species, including those of Schoenoplectus, Baumea and Juncus which are commonly used for wastewater nutrient-stripping. In some cases, such as in the leaves, twice as much nitrogen (N) and one and a half times more phosphorus (P) is assimilated in the Triglochin tissue. In all parts of the plant there has been an increase in Total N and Total P. Investigations were conducted using different environmental conditions for the plants. A comparison was made between root zone (substrate-only) and complete pond conditions, with some changes to loading rate and retention times. Triglochin huegelii has many practical applications in wastewater management, especially if the level of influentlwastewater can be controlled, thus allowing sufficient time for Triglochin huegelii to respond with changed structure and morphology. Proline, a substance known to be produced by plants under stress (such as changing water levels), was detected in Triglochin huegelii. In a pond, the leaves of Triglochin can be directly involved in nutrient absorption and assimilation. A study of leaf structure and other aspects of its biology showed that nutrients can easily pass into leaf tissue and then into other regions in the plant. In Triglochin huegelii, nitrogen was primarily stored or found in leaves then tubers then roots, while levels of phosphorus were higher in tubers then roots then leaves. The above-ground:below-ground (AG:BG) ratio of Triglochin huegelii also depends on the water regime. For all samples, whether pond or substrateonly, the ratio was 0.84. However, when consideration is given to pond conditions the ratio increases to 1.11. It appears that in pond conditions, and especially with long retention times, proportionally more above-ground growth (leaves) occurs and in substrate-only conditions, proportionally more biomass is found below-ground, with the number and size of leaves reduced in these plants. The highest nutrient levels recorded for Triglochin huegelii were 11.74 mgP/g and 35.7 mgN/g dry weight. Triglochin huegelii has been found to have a protein content of at least 1.7 g/100 g wet weight in the leaves, and less in roots and tubers. Triglochin huegelii could have potential as a fodder source because of its high protein content, similar to that of lucerne. Triglochin huegelii seems to remove nitrogen and phosphorus at a greater rate than many other types of aquatic macrophytes. Other parameters such as BOD, Suspended Solids and fecal coliforms were also examined, with reductions of up to 90%, 84% and 99% respectively. The implication is that instead of only planting the perimeter of lagoons, artificial wetlands and constructed basins we should be planting the bulk of the waterway with submergent species such as Triglochin spp which are far more effective in stripping nutrients than emergents currently used for that purpose. In addition, systems need to be designed that mimic natural ecosystems, and yet are economical and functional. This current research can be used as a basis for further study to establish the extent of nutrient removal by Triglochin huegelii and its interactions with other macrophytes in polyculture systems.

The aim of this PhD research was to study multi-element composition in wetland plants from contrasting habitats, including hot springs, temporary wetlands, and metal-rich areas. Triglochin maritima L. (seaside arrowgrass) was chosen for the study because this species is common in alkaline/saline soils and is adapted to diverse habitats. Eleocharis rostellata, Juncus balticus, Salix exigua, S. boothii, and S. wolfii were also included in the study. Field studies and greenhouse experiments were conducted to study the multi-element composition in plants. In the greenhouse experiment the effects of temperature and soil biota on multielement uptake in T. maritima were studied. Root-zone soils and plant samples were analyzed for 32 - 50 elements using inductively coupled plasma OES/MS spectrometry. The expected outcomes from this research were: 1) the development of multi-element fingerprints for T. maritima and other plant species from contrasting habitats, and 2) a better understanding of the effects of temperature and soil biota on multi-element uptake in T. maritima. Habitat specific element concentration patterns in T. maritima were observed; concentrations of Mn, Li, and B were high in plants from hot spring influenced wetlands, whereas Ca, P, Mg, Fe, Sr, Ba, Ti, and Cu were higher in the plants of temporary wetlands. J. balticus and Salix species from mine impacted and uncontaminated sites revealed distinct differences in multi-element fingerprints. J. balticus showed high concentrations of S, K, Mn, Fe, Cu, Al, As, and Cd at contaminated sites compared to un-contaminated sites. Multi-element fingerprints of Salix species showed that S. boothii had higher concentrations of Mn, Fe, Al, and Ti compared to S. exigua and S. wolfii. To our knowledge for the first time the association of mycorrhizal fungus in T. maritima was confirmed, and significant effects of temperature on element concentrations, contents, and their translocation in plants were observed. Generally, the distribution of the total contents of P, Na, Mn, B, Cu, Mo, Li, Sr, Ti, and Cs in both roots and leaves were lower at 40 °C compared to 20 and 30 °C, but their distribution and translocation from root to leaves were higher at 40°C. Even though the biological and physiological functions of Li, Sr, Ba, Rb, and Ti in plants are not fully understood, these elements were substantially taken up by T. maritima, and significant positive correlations of these elements were found with elements that have known biological functions. Overall, concentrations of Ca, P, Mg, Mn, B, Sr, and Ba in T. maritima showed variation due to differences in habitats, temperature, and experimental growing conditions (greenhouse and field condition). Concentration patterns of Na, K, and Zn were species specific and affected by temperature. Li concentrations varied due to habitat differences, growth conditions, and species differences. Future research directions could include: 1) identification of the fungal species associated with T. maritima and studies to elucidate their possible role in survival of T. maritima in the elevated temperature of hot springs, 2) the effects of soil factors, such as salinity and 3) seasonal variation in uptake and translocation, particularly for the less studied elements with yet unrecognized but potential biological functions in plants. / NIH Grant Number P20 RR016471 from the INBRE Program of the National Center for Research Resources / North Dakota State University. Department of Biological Sciences / Robert H. Levis II Cross Ranch Fellowship / North Dakota State University. Environmental and Conservation Sciences program

Increasing human pressure combined with sea level rise and increased storminess is threatening coastal ecosystems around the world. Among these ecosystems, saltmarshes are particularly endangered due to their position in temperate areas with low wave action where human density is often high (e.g. estuaries). Around the UK, centuries of land reclamation have led to a substantial decrease of the area of saltmarsh. Over the past decades, restoration schemes have been implemented in numerous coastal locations in an attempt to counteract this loss. Such schemes involve allowing sea water to inundate a previously embanked area and letting the vegetation develop naturally, thereby reverting to saltmarsh through natural colonisation. However, surveys of restored areas that have looked at the recovery of plant species diversity or functional characteristics often show that restored saltmarshes do not reach the state of a natural saltmarsh ecosystem. While there is much data at the species level, recovery of plant intra-specific diversity (genetic diversity) has not been assessed in restored saltmarsh although this component of biodiversity is receiving increasing attention for its effect on ecosystem function. This thesis represents the first attempt to (1) characterize the nation-wide genetic structure of two important north-west European saltmarsh plant species, the common saltmarsh grass (Puccinellia maritima) and the sea arrowgrass (Triglochin maritima) and (2) compare levels of genetic diversity and structure between restored and natural ecosystems. Microsatellite molecular markers were developed for both species. Using innovative methods to analyse the genetic data obtained for these two polyploid species, this thesis highlights that genetic diversity at the national scale is organised regionally for both species, although gene-flow is still restricted between populations within the same region. Gene-flow between populations is determined by different processes depending on the species. While coastal processes mainly influence gene dispersal in P. maritima, overland routes of dispersal are involved for T. maritima. These differences are believed to be due to differences in dispersal ecology between the two species. Although gene-flow exists between distant saltmarshes, the genetic analysis of P. maritima and T. maritima colonists arriving on restored sites highlighted their local origin and reaffirmed that it is preferable to restore saltmarsh where a nearby natural saltmarsh can act as a source of colonists. A multiple paired-site comparison identified similar genetic diversity between restored and natural saltmarshes indicating that restoration of local genetic diversity is rapid for both species. A single site comparison at Skinflats in the Forth estuary compared fine-scale spatial genetic structure between the restored and natural saltmarsh. Interestingly, no structure was detected for T. maritima either in restored or natural saltmarsh. In contrast, a strong genetic structure organised along the elevation gradient was observed in the natural saltmarsh for P. maritima but was absent in the restored saltmarsh. The origin of this structure is not clear but could be due to restricted gene-flow between individuals from different elevations due to strong post-zygotic selection, as suggested in previous work. In any case, this lack of structure in the restored saltmarsh indicates that genetic recovery is incomplete in this respect for P. maritima. This thesis introduces the growing field of restoration genetics to saltmarsh ecology and identifies the principal population genetic trends in two of the species dominating the vegetation of north-west European saltmarshes community. The information given here will be useful for restoration practitioners and provides a strong foundation for future work characterizing the importance of genetic diversity for saltmarsh function.