Date of Award

2005

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Plant, Soil, and Environmental Sciences

Advisor

Laurie J. Osher

Second Committee Member

Joseph T. Kelley

Third Committee Member

Hilary Neckles

Abstract

Submerged sediments represent an important component of near-shore coastal systems. Until recently, submerged sediments have only been studied by geologists, sedimentologists, and benthic ecologists. Soil scientists have begun to study submerged sediments from a pedological perspective and have termed them subaqueous soils. Subaqueous soils are those organic or mineral materials, having the ability to support rooted plants, which are submerged by estuarine, marine, or lacustrine water for a period of time such that their pedogenesis reflects an environment dominated by submergence; i.e., presence of a thin, oxidized surface horizon underlain by thick gleyed or reduced horizon(s). The objective of this study was to identify and classify subaqueous soils within a 589 hectare study site of the Taunton Bay estuary, located in Hancock County, Maine, and to determine if there is a relationship between subaqueous soil nutrient content and eelgrass (Zostera marina) persistence. Between 1996 and 2002, eelgrass within the study site decrease by 66%. A detailed bathyrnetric map was created for the study site using tools such as tide gauges, fathometers, global positioning systems (GPS), and GIS software. The resultant map displayed water depths within the study site between 0.5 meters and 21.0 meters below mean sea level. The bathymetric map was used to identify water depth and slope, two components necessary in identifying subaqueous landscape units. Landscape units were identified according to depth, slope class, geornorphic position, depositional environment, and preliminary soil sampling. Soils were collected using a bucket auger, McCauley peat auger, or vibracoring device to depths between 1.0 meter and 5.0 meters below the soil surface. Soils were described and classified according to the National Soil Survey Center and the Soil Survey Staff. Six 200 meter transects were established within the study site, two in each of three eelgrass percent cover zones: high, medium, and low. Percent cover of eelgrass was recorded every ten meters along each transect using a quarter quadrat. Ten soil samples were collected horn each trailsect and analyzed for nutiient, organic matter, acid volatile sulfide (AVS), and chromium reducible sulfide (CRS) concentrations to determine the relationship between subaqueous soils and eelgrass persistence. Seven subaqueous landscape units were delineated within the study site. Associated w~thth e seven landscape units were ten subaqueous soil map units. Soil map units were classified to three great group and three sub-group classes, the most common of which was Typic Sulfaquent. Nutrient, organic matter, AVS, and CRS data from vegetation transects suggested that there is no relationship between subaqueous soils and eelgrass persistence in the Taunton Bay study site. Soils from high and low cover transects had statistically similar concentrations for most of the analytes studied. In contrast, data for soils collected from the medium cover transects was statistically different from the high and low cover transects for most analytes.

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