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acase@tulane.edu / Ecogeomorphology is the study of interactions and feedbacks between the physical surface processes and biological communities in an ecosystem. These interactions are under-studied in wetlands associated with river deltas, and are of vital importance to the deteriorating wetlands of South Louisiana. As the state of Louisiana implements its Comprehensive Master Plan for a Sustainable Coast, which relies heavily on diverting Mississippi River water in order to create new wetlands, a detailed understanding of ecogeomorphological relationships is required to create accurate predictive models to design and assess future projects. This research is comprised of three studies of such relationships in the West Bay Sediment Diversion near Venice, LA, and has resulted in the following key findings: 1) the composition of the buried seed bank suggests a shift from river-derived to within-system propagules as the marsh develops, 2) emergent plant roots increase the cohesion of marsh soils, especially when grasses, sedges, and woody species dominate the vegetation, and 3) a competition experiment between the native sedge Schoenoplectus deltarum and the invasive grass Phragmites australis indicated that the two species performed approximately equally in mixture, regardless of abiotic stressors, while the stressors did affect productivity of each species grown in monoculture. These three studies are unified by the role of wetland vegetation as an increasingly important autogenic modifier of other wetland processes during the early development of the marsh. / 1 / Alexander D Ameen

Floodgates were constructed in 1971 on the main creek draining Hexham Swamp, a large wetland on the floodplain of the lower Hunter River, New South Wales. Substantial changes in vegetation have occurred in Hexham Swamp subsequent to the construction of the floodgates. Previous areas of mangroves and saltmarsh have been reduced (180ha to 11ha, and 681ha to 58ha, respectively), and Phragmites australis has expanded (170ha to 1005ha). Much of the mangrove loss (ca. 130ha) was a result of clearing, and the remainder has gradually died off. The factors contributing to the dieback are likely to be a combination of drying of the soil, root competition and, at times, waterlogging. Field sampling as well as microcosm and reciprocal transplant experiments involving key species, Sarcocornia quinqueflora, Sporobolus virginicus, Paspalum vaginatum and Phragmites australis, suggest that a reduction in soil salinity has been an important factor in initiating successional change from saltmarsh to Phragmites reedswamp. The data also suggest that increased waterlogging has been an important factor in initiating vegetation change. This apparently paradoxical result (floodgates and associated drainage generally result in drying of wetlands) is likely to have resulted from occlusion of drainage lines (by sediment and reeds) and is, therefore, likely to be a condition that developed gradually. That is, the initial effect of the floodgates is expected to have been a drying of the swamp, followed over time by an increasing wetness. An examination of vegetation changes after removal of cattle from part of Hexham Swamp, suggests that grazing had little effect on species composition of vegetation or rate of expansion of Phragmites australis. However, grazing does affect vegetation structure (height and density), possibly favours some coloniser species (e.g. Sarcocornia quinqueflora) in particular environmental conditions, and possibly inhibits establishment of Phragmites australis.

Thesis (M.S.) -- Mississippi State University. Department of Biological Sciences. / Title from title screen. Includes bibliographical references.

<p> As highway runoff is one major source of non-point pollution in urban areas, removal of contaminants in runoff should be of great concern. In this paper, the necessity of highway runoff treatment in Shanghai was approved, systemic comparisons between runoff treatments were listed, detailed discussions on treatment approach selection were given based upon the availability of land. Three design models for highway runoff treatment were proposed; one focused on the urban highway, one focused on the suburb highway, and the third focused on the urban-suburb area. A survey among scientists studying runoff in China showed that the use of constructed wetlands was a remedy that was highly approved. They also supported the establishment of an urban runoff database. This paper will assist in the development of suitable treatment strategies for highway runoff in urban areas in China.</p>

As highway runoff is one major source of non-point pollution in urban areas, removal of contaminants in runoff should be of great concern. In this paper, the necessity of highway runoff treatment in Shanghai was approved, systemic comparisons between runoff treatments were listed, detailed discussions on treatment approach selection were given based upon the availability of land. Three design models for highway runoff treatment were proposed; one focused on the urban highway, one focused on the suburb highway, and the third focused on the urban-suburb area. A survey among scientists studying runoff in China showed that the use of constructed wetlands was a remedy that was highly approved. They also supported the establishment of an urban runoff database. This paper will assist in the development of suitable treatment strategies for highway runoff in urban areas in China.

ABSTRACT Sipuncula is a group of unsegmented, coelomate, bilaterally symmetrical and wormlike marine deposit-feeding benthic macro-invertebrates. They are abundant along the intertidal habitats and around 150 species have been recorded worldwide. Sipunculans likely accumulate many anthropogenic contaminants by feeding on the contaminated sediments or benthos, and since they are edible marine species and have long been used in Southwest Pacific cuisine, these contaminants may transfer into the food chain and affect the public health of humans.Trace elements and PAHs are the most common contaminants that appear in the coastal areas worldwide. These contaminants lead to losses in oceanic yield and may hazardous effects on health when they enter the food chain. The previous studies of sipunculans along the coast of Taiwan were mostly focused on the taxonomy and distribution of the species living on the hard -ground habitat (rubble), one of the purposes of this study is aiming at the sipunculans on the seagrass beds and wetland soft-ground habitat for species diversity, population dynamic and ecological related research. Among 10 native sipunculans species, Sipunculus nudus is the dominant species living at the segrass bed and wetland in Taiwan. Siangshan wetland locates at the area of industrial pollution and S. nudus here is a species with aquatic economy, but is known limitedly of its population and environmental physiology. Therefore, the other purpose of this research is to investigate the S. nudus population in this wetland and analyze the trace elements: arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and zinc (Zn) and the organic pollutants: PAHs, in order to understand the bioaccumulation of S. nudus in the above two types of soft-substrate regarding the pollutants. The main results of this study are as follows: (1) This study represents a pioneering investigation in Taiwan regarding the species diversity of sipunculans on the seagrass meadow soft-ground sediment, which describes the species and their morphological characteristics. A total of 42 specimens 10 sipunculan species belonging to 3 families were identified. (2) It is the first time that S. nudus is realized as the dominant species in these soft habitats. Because of its cultivation potential, its population dynamics and reproductive cycle in Siangshan wetland were studied. The population size of S. nudus in this area is 0.965¡Ó 0.46 ind.m-2 and the sex ratio is around 1:1; the reproductive period is from April to September in the year with the peak reproductive period from May to August; the body length of matured individual is over 11cm. (3) This is the first report in Taiwan on the trace elements in sipunculan and their surrounding sediments. The bioaccumulation characteristics of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and zinc (Zn) were analyzed and compared in two sipunculan species, S. nudus and Siphonosoma vastum, which were collected from seagrass beds and wetlands in Taiwan. Both sipunculans in the these soft habitats had a high Cu bioaccumulation mechanism. Multivariate analysis, principle component analysis, and partial least squares for discriminant analysis of trace element levels and bioaccumulation factors were used to distinguish the element distributions that corresponded to the two habitats (seagrass beds and wetlands). Different levels of certain trace elements in these two sipunculan species may result not only from the environmental factors of various habitats but also from the accumulation characteristics of various species. The As, Cd, Cr, Cu, Hg, and Zn concentrations were markedly lower in sipunculan than in other invertebrates from the adjacent polluted regions. (4) This is the first report on the accumulation situation of PAHs in different body tissues (tentacle, nephridium, intestine, and muscle) of S. nudus in Taiwan. It was found that the smaller individuals had higher amount of PAHs with higher percentage of low-ring PAHs and they were mostly concentrated in the nephridium. This study provides the bioaccumulation pattern of PAH in the tentacle, nephridium, intestine, and muscle of S. nudus. The logKow and logBAF parameters show that S. nudus may excrete or decompose high-ring PAHs via biotransformation. By comparing the t-PAH of S. nudus with that of the surrounding substrate and invertebrates along the coasts of other countries, the t-PAH content in the muscle of S. nudus is lower than the sediment and the invertebrates. As a result, I suggest removing the internal organs and utilizing the muscle portion as good to reduce the uptake and accumulation of PAHs from the sipunculans.

The development of graduate students in the sciences preparing for careers in academia has long included elements to advance students as science researchers, but recent emphasis is being placed on developing students as instructors and education researchers as well. As such, objectives of this study included assessments of seedling responses to hydrology typical of floods in urban settings, the role of created microtopography in community development of a bottomland hardwood forest, and the influence of geographic information systems (GIS) on student motivation and conceptual knowledge. Substantial losses of bottomlands in Texas necessitate restoration to regain the ecosystem services that they provide. Restoration of proper hydrology is the most important aspect of wetland restoration, but this can prove difficult in urbanizing environments where hydrology has been irreversibly altered. Microtopography has been shown to be an important component of bottomland hardwood forests, and its restoration may aid in hydrologic restoration as gradients are created that support a diverse community. Tree seedlings were subjected to experimental flooding regimes typical of floodplain forests in rural and urban settings. Growth rates of seedlings varied over time and differed depending on species and treatment. Created microtopography resulted in a spatially heterogeneous system similar to that of natural bottomlands and strongly influenced hydrology, soil properties, survival of planted seedlings, and abundance and distribution of colonizing species. Proper bottomland restoration in urbanizing environments should include species selection based on current and potential future hydrologic conditions. In addition, restoring microtopography may improve survival of a variety of species introduced during restoration, as well as enhance colonization of a diverse plant community under changing hydrologic regimes. Trends indicated a slight improvement in attitude and performance for students that used GIS. More important, the authenticity of the experience appeared to affect student attitude. The effective use of GIS in teaching may be scale-dependent. Smallscale phenomena may be assessed as easily in a field exercise as with GIS. Using GIS to assess large-scale, complex patterns may have a substantial impact on student understanding. Further studies are needed to determine direct benefits of teaching with GIS in undergraduate ecology classrooms.

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