The purpose of this study is to examine the sediment stratigraphy and oyster reefs of Lavaca Bay. There has been little previous research on the bay??s stratigraphy, and information from this study is important for industry and resources management. The Lavaca Bay estuary is a drowned river valley containing a history of estuary development in the late Pleistocene and Holocene. We used a chirp sonar to gather acoustic reflection profiles, which were classified to categorize and trace reflectors. The data were plotted to make maps of the distribution of various reflection types and contour maps of reflector surfaces. The maps were compared with previous studies of Lavaca Bay and Galveston Bay to aid interpretation. The vertical sediment stratigraphy showed two main reflector packages. The upper package, bay bottom to ~25 m depth, is mostly acoustically transparent with a few, semi-continuous, prominent reflectors in the upper 5-10 m. The lower package ranges from 15-40 m depth with several strong reflectors sometimes underlain by unconformities. To classify reflector characteristics, the upper package was divided into two categories, each with 4 sub-categories: 1) surface reflectors??weak, medium, strong, and ringing, which describe the general acoustic return of the bay bottom, and 2) strong, shallow reflectors??surface strong, mounds, buried strong, andburied multiples, which describe strong acoustic returns in the upper 5 m of stratigraphy. Within the lower package, four categories were recognized: 1) subbottom reflectors/horizons, occurring ~20-40 m depth, 2) deep wipeout (incoherent/wipeout zone), ~10-30 m depth, 3) clinoforms, ~5-30 m depth, and 4) terraces, ~10-30 m depth. The data interpretation agrees with previous studies suggesting Lavaca Bay filled beginning with coarse sediment and grading to finer sediment. In addition, the surface type reflectors are indicative of bottom type, the strong, shallow reflectors are largely indicative of oyster reef/shell, and the subbottom reflectors are related to the Pleistocene and bay fill. The location/extent of oyster reefs in the bay does not agree well with previous studies, suggesting either oysters do not grow over older ones or differences between the chirp sonar response and other methods significantly differentiate the interpretation of their locations/extents.

The oyster culture site is located at the nearshore of Tainan city where it not only has an abundance of phytoplankton for feeding oysters but also has suitable water temperature for growing oysters. Each year the harvest of oyster has brought a good fortune to local fishermen and their household, therefore raising oyster is a very important industry for the Tainan city. Up to the present, the land-based fishery has many difficult problems such as the increasing cost of feed, over pumping of groundwater and lack of efficient treatments for fish diseases. All these difficult situations have given the offshore oyster culture a great opportunity to develop since no feed cost is required and if clean offshore sites are selected for growing oysters. This paper focuses on the problems met in the growing process including oyster raft engineering, biotechnology, marine environmental monitoring and the hygiene problems etc. Finally, several suggestions of oyster value improvement have been provided for the fishermen.

In Galveston Bay, Texas, the eastern oyster, Crassostrea virginica, is found throughout the bay both intertidal along mudflats and subtidal where their self-built reefs extend vertically deeper. The eastern oyster is an important ecological and economical resource and as such has led to studies regarding their community structure to permit effective creation of artificially built reefs and restoration of existing ones. The presence of the oil and gas industry coupled with increased oyster mortality led to investigations to determine the effects of petroleum substances on the setting, growth, and mortality of the eastern oyster. Many of those studies indicated increased settlement and increased growth of oysters on substrate coated with oil. A field conducted experiment was used to assess the settlement of oyster larvae on cleaned oyster shells coated with two different types of petroleum substances (mineral oil and motor oil), comparing viscosities, in a shallow bayou in Galveston, Texas, where the eastern oyster dominates the intertidal zone. Oyster shells were used as cultch material and divided into three groups; a non-treated control group, mineral oil treated group, and a motor oil treated group. Nekton assemblages, distributions of the ivory barnacle, Balanus eberneus, and Dermo disease infection were assessed. Settlement of oyster larvae occurred in all three groups with no significant difference of preference; algae and sediment present on the shells coupled with the presence of predators most likely caused reduced numbers of spat settlement. Species richness was equal among the groups but varied in evenness of individual species.

Thesis (M.S.)--Oregon State College, 1953. / Typescript. Includes bibliographical references (leaves 47-48). Also available online.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographical references (leaves 50-60).

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 80-96). Also available on the World Wide Web.

Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on June 18, 2009. Major professor: Lars Tomanek. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Biological Sciences." "June 2009." Includes bibliographical references (p. 33-37). Also available on microfiche.

Thesis (Ph. D.) - University of North Carolina, 1961. / Bibliography: leaves 41-46.

Proefschrift--Amsterdam. / "Samenvatting": p. [xiii]-xvi. "Stellingen": [3] p. inserted. Bibliography: p. 237-249.

Thesis (M.S.)--University of North Carolina at Wilmington, 2006.