Thesis--Yale. / "COO-3573-22." Includes bibliographical references (leaves 146-156).

Salt marshes are coastal wetlands that are highly productive and biologically diverse ecosystems. These systems are under threat from rising sea levels which are predicted to accelerate in the future. Salt marsh habitats of the Swartkops, Kromme and Knysna estuaries were examined to determine their structure along an elevation gradient and how this structure has changed over the past six decades, what the primary drivers of this structure were and whether the salt marsh surface is stable, rising or declining relative to predicted sea level rise. During this study the following main hypothesis was tested: The environmental drivers of salt marsh zonation are elevation above mean sea level (AMSL), soil moisture and soil salinity, all of which will be impacted by the predicted rise in sea level of 1.48 mm.y-1, unless the salt marshes are able to accrete at a rate such that surface elevation gain is sufficient to offset the rate of sea level rise. The results showed that the salt marsh vegetation structure followed a predictable pattern down the elevation gradient with distinct supratidal, intertidal and subtidal habitats identified for each estuary. These three zones occurred between elevations around Mean Sea Level of -0.86 to 2.42 AMSL for Swartkops, -0.3 to 2.95 m AMSL for Kromme and -0.48 to 3.14 m AMSL for Knysna. A floodplain component was also identified in the Swartkops estuary, which was restricted to the upper reaches. During the last 60 years, losses of intertidal and supratidal salt marsh for Swartkops were 74.31 ha and 30.23 ha respectively, 17.01 ha of intertidal and supratidal salt marsh was lost in Kromme while intertidal salt marsh in Knysna has diminished by 168 ha. These losses were mainly attributed to developmental pressure, although there are indications that rising sea levels are becoming more influential in the lower reaches. The main environmental drivers for salt marsh structure in the Swartkops were shown to be soil moisture content and elevation, soil moisture and organic content for Kromme while elevation and soil redox potential were dominant in Knysna. In a comparison of all three systems, soil moisture content and redox potential were found to be the most important drivers of vegetation distribution. Elevation dictates tidal inundation periodicity and frequency, and thus acts to influence all edaphic factors driving vegetation distribution. Results indicated that the salt marsh surface elevation of the lower and middle sections of the Swartkops, Kromme and Knysna estuaries are generally declining relative to current sea level rise. Where increases in surface elevation (relative to current sea level rise) were recorded, the majority of the accretion occurred after episodic flooding in winter 2011. These increases typically occurred in the upper reaches and were attributed to the deposition of fluvial sediments as a result of these floods. Results for Knysna indicate that while a majority of the salt marsh surface is accreting vertically, only three areas are increasing their elevation at a rate at least equal to current sea level rise. In these areas, developmental pressures will prevent a landward transgression of the salt marsh, forming an artificial “coastal squeeze”. Geomorphological limitations (steep hills adjacent to the salt marsh) will prevent any transgression in the upper reaches of the Kromme Estuary. Supratidal habitat in the upper reaches of the Swartkops estuary, if undeveloped, will provide the only viable habitat for the salt marsh to migrate into, given sufficient surface elevation.

The development of a late Holocene salt marsh was studied on the inactive part of the Fraser Delta at Boundary Bay, southwestern British Columbia. Present-day vegetation zones near 64th Street, South Delta, in the western part of the Bay, were distinguished in the salt marsh and were related to zones found in cores obtained in a transect across the marsh. A sequence of development, related to elevation, was determined. Salicornia and Triglochin are pioneer colonizers of the tidal flats and are sometimes associated with areas elevated by algal mats. As the area was elevated, sediments were trapped by vegetation and stabilized by rhizomes, and other halophytes grew, including Cuscuta, Sperqularia, Atriplex, Distichlis, Grindelia, and Plantago. A zone characterized by abundant Atriplex represents positions of former strandlines. As further emergence occurred, mesophytes became dominant and, in the landward, most emergent zone, a diverse flora of Maius, Sjdalcea, Aster, AchiIlea, Solidaqo, Elymus, Angelica, Juncus, and grasses developed. A radiocarbon date on Salicornia-rich organic silts at a depth of 35 to 40 cm in core 5 suggests that salt marsh development commenced 320 ± 70 years B.P. (GSC-3186). A former salt marsh peat is now partially buried and being actively eroded where exposed near 112th Street, South Delta, in eastern Boundary Bay. A paleoenvironmental reconstruction suggests the peat started developing in freshwater, with ferns, sedges, Typha, and Nuphar. Later, it was successively inundated by marine water and a salt marsh developed, as seen by an increase in the abundance of chenopod pollen. Subsequent emergence of the salt marsh was accompanied by the development of an increasingly diverse vegetation. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Any marsh is a distinctive land-forrm of varied interest. To the agriculturist it is wasteland to be reclaimed; to the naturalist, a habitat of aesthetic value. To the ecologist, however, a marsh represents a complexity of vegetation under the influences of many and often inseparable factors. It becomes a place of challenging study. There exists a notable lack of information treating the ecology of inland salt-marshes. Still less known are the ecological conditions imposed upon plant life in marshes arising from saline springs. The presence of such a wetland in western Utah afforded the opportunity to study salt-marsh vegetation in a highly specialized habitat. The study had two phases. First was a study of the vegetation. Data were secured from collections and study plots within each of the major marsh communities. General descriptions of other plant life were additionally compiled. It is not within the scope of this paper to discuss or rigidly define the requirements embraced in the use of "community" as a unit of vegetation. Sufficient references are available for those who wish to pursue the point. In this study, a community is a congregation of plants exhibiting differences in appearance and species composition from other plant congregations. Secondly, studies were directed to the influences of soil and water on the ecology of each community. Transects were used to investigate many of these relationships. Transition zones between communities were narrow and usually sharply delineated. Transects intersected ecotones of this sort; environmental differences which may have occurred in the few broader ecotones were assumed to be of equal magnitude but of more gradual rate of change . Relatively short transects thus adequately represented each community yet allowed collection of intensive data. Information and data were collected during a 5-week period in August and September 1959 and a 6-month period beginning in March 1960.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 161-166. / by Jayne Loring Fifield. / M.S.

Coastal ecosystems, such as the salt marsh of the Georgia coast, have long been valued for decision-making purposes based on market-values of goods and services including: fishery landings, hedonic pricing of waterfront homes, and tourism dollars. These values do not show the full picture of services provided by these ecosystems. Using focus group discussions and key informant interviews I investigate socio-cultural values and benefits provided by salt marsh ecosystems in central coastal Georgia. Participants noted that through their experiences in marshes they developed a desire to be stewards. This desire, coupled with the industrial pollution, residential development, and sea-level rise threats in the area result in a need for cooperative conservation and thus better enforcement of existing regulations. This relational value persisted across geographic locations and sample populations. My results show the importance of utilizing diverse members of community to elicit qualitative value statements. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Human reliance on the goods and services provided by ecosystems and the global decline in the health of many of these ecosystems, necessitates ecosystem valuation for the purposes of decision-making and conservation policy. The literature suggests that conventionally employed economic valuation methods have been unsuccessful in capturing the full scope of the benefits ecosystems provide, particularly those benefits that are considered cultural. This research explores public perceptions of salt marsh value through the use of focus groups in marsh-adjacent communities in Massachusetts, Virginia, and Georgia. Results suggest that in case study communities, outdoor experiences in salt marshes inspire serenity in Massachusetts, shape shore and “marsh” identities in Virginia, and promote stewardship cultivation in Georgia. Perceived threats to these benefits, such as the threat of residential development, industrial pollution, and increasing flood risk, together constitute the context for various community responses related to marsh protection. Results contribute to existing economic valuations. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

No description available.

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: John C. Kraft, Dept. of Geology. Includes bibliographical references.

One of the most recognised values of tidal salt marshes is the ecosystem service they provide as natural sinks for contaminants such as metals. This study examines net accumulation of metals (As, Cr, Cu, Hg, Ni, Pb, Zn and V) over a 5-yr period, from 1997 to 2002, in surface sediments of salt marshes in the Bay of Fundy, Canada. Metal accumulation has been measured in seven sites that extend from outer to inner Bay and in low and high marsh areas within each site. Overall, sediment metal concentrations are at or near their natural levels. Concentrations of metals show variability among marshes but are not significantly different between low and high marsh. Concentrations of As, Hg, Pb and V appear to be influenced by anthropogenic inputs. Calculated sediment loading rates for these metals generally showed gradients of increased loading from outer to inner Bay. Variability in sediment deposition rate is the driving force behind this spatial pattern. Results of this study suggest that the value of salt marshes as a sink for metals may be enhanced by high sedimentation rates.