This study examines modern relationships among salt marsh plant species and their pollen in three salt marshes located on the northwest coast of the Bay of Fundy, New Brunswick. Linear regression analysis of pollen in 35 surface sediment samples and vegetation cover on small (<15 m) and broad (>15 m) scales show that, with the exception of Poaceae and Cheno Am, pollen corresponds well with fine-scale patterns of salt marsh vegetation. Scatter diagrams of paired pollen and cover data illustrate that cover of Triglochin is over-represented by its pollen, Glaux is under-represented, and Poaceae, Cheno Am, and Plantago are inconsistent. Tidal mixing and differential inputs from local, regional, and extra-regional sources with elevation limit the establishment of plant-pollen relationships for Cheno Am and Poaceae but not for other taxa. Comparison of 35 modern analogs from five vegetation zones using squared chord distance show that zones are distinct such that the marsh-terrestrial interface can be tracked with the greatest degree of certainty in a salt marsh paleo-ecological record and other marsh zones can be tracked when a conservative threshold of dissimilarity is used.

The structural framework of the northern Gulf of Mexico coastal zone is characterized by numerous growth fault systems. Neotectonic processes in coastal marshes in this region have been shown to be important drivers of relative sea-level rise as well as having significant influence on marsh accretion processes. One active growth fault has been identified at East Matagorda Peninsula, Texas. To characterize the Holocene behavior of this fault and the consequent sedimentary responses, a suite of fallout radionuclides (7Be, 137Cs, 210Pb) and radiocarbon, supplemented by sediment physical property data have been used to determine sediment mixing depths, rates of accumulation, and geochronology. Correlation of time-equivalent stratigraphic boundaries reveals a maximum total Holocene offset of ~1 meter. Determination of slip rates from these values reveals a linear trend of displacement as a function of distance along the fault trace with maximum slip occurring to the southwest and minimum slip to the northeast. Sediment accumulation rates from the downthrown station nearest to the fault trace display a dramatic increase over the last 30 years. Sediment bulk density and grain size data suggest an interaction between fault-driven geomorphic change and sedimentation where a migrating land-water interface has influenced the type of sediment accumulation here.

Redhead duck (Aythya americana) nesting and habitat change was studied in Knudson Marsh, Utah, in 1974 and 1975, and compared with earlier studies from 1950 and 1955 on the same marsh. Water conditions in 1975 were found to be similar to those in 1950, both years of favorable habitat, yet there was a decline in numbers of redheads from 500 pairs in 1950 to 50 pairs in 1975. The number of nests found also declined from 151 in 1950 to 49 in 1975. Water conditions were poor in 1955 and slightly more favorable in 1974, but there was a decline from 95 pairs and 49 nests in 1955 to 50 pairs and 23 nests in 1974. Success of active nests was greater in the present study than in 1950, but hatching success in successful nests was greater in 1950. No appreciable change in the vegetational composition of the marsh was detected between 1950 and the present study.

This experiment manipulated water levels in boreal marshes within the Saskatchewan River Delta, a 9500 km2 region in northern Canada. Water levels in three wetland cells were lowered in a partial drawdown by a mean of 0.32 m. Water clarity, nutrient concentrations, and periphyton nutrient limitation were measured over the summer preceding and the summer following manipulation. The water levels of three adjacent control wetlands were not manipulated. Lowering wetland water levels reduced the wind velocity necessary to resuspend bottom sediments, which led to increases in turbidity, dissolved organic carbon, and concentrations of organic and inorganic nitrogen and phosphorus. Prior to drawdown, wetland periphyton communities were limited by nitrogen or co-limited by nitrogen and phosphorus. The input of nutrients from the sediment resulted in a shift from nutrient deficiency to nutrient sufficiency. Periphyton and phytoplankton production increased in response to the nutrient input. Increased turbidity, nutrient concentrations, and algal production were correlated with depth, rather than being inherent to the drawdown condition. Other water level manipulation studies have found that a reflood after a period of total drawdown caused a pulse of nutrients leaching from decomposing litter. This work suggests that these changes may not require complete drying out of sediments, or the input of large amounts of litter from drowned annual mudflat species, but rather can occur when depths are shallow enough that sediments are more frequently resuspended by wind. These findings have implications for future management of these marshes for waterfowl and muskrat production.

Thousands of hectares of wetlands are being destroyed by oil sands mining in Alberta, and the industry must undertake wetland reclamation to compensate for these losses. Wetland vegetation has developed at some previously mined sites, however reclamation is thus far exploratory, and limited in extent. To inform reclamation practices and assist compliance monitoring I examined vegetation communities in 25 natural boreal wetlands and 20 oil sands reclaimed wetlands, developed a Vegetation-based Index of Biological Integrity (vIBI) to quantify the ecological health of wetlands, and identified possible physical and chemical barriers to reclamation. The vIBI identified 6 reclaimed wetlands in fair to good health, however reclaimed wetlands have different vegetation communities, do not produce the same level of aboveground biomass, and have lower levels of sediment nutrients than natural wetlands. To reclaim healthy wetlands, planning should focus on establishing appropriate species, and alleviate nutrient and sediment deficiencies. / Ecology

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 100-108). Also available on the World Wide Web.

Thesis (doctoral)--Tartu University, 1999. / Curriculum vitae. Includes bibliographical references.

"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Title from PDF of title page (Georgia Southern University, viewed on April 5, 2010). Stephen P. Vives, major professor; Sophie B. George, Risa A. Cohen, committee members. Electronic version approved: December 2009. Includes bibliographical references (p. 37-40).

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : 78-82).

Thesis (M.Sc. (Zoology & Entomology)) - Rhodes University, 2009.