Originally presented as Thesis (Ph. D.)--University of Cambridge. / Includes bibliographical references and index.

Originally presented as Thesis (Ph. D.)--University of Cambridge. / Includes bibliographical references and index.

Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 143-164).

In recent years, intertidal reefs of Crassostrea virginica (eastern oyster) along central Florida's east coast have suffered extensive losses due to wakes from recreational boats. These wakes have caused extensive shell movement and sediment resuspension which results in large piles of disarticulated shells along the seaward edges of reefs. Dead margins extend up to one meter above mean high water. The creation and enforcement of "no wake" zones in the area are unlikely. Thus, there is an urgent need for an alternative restoration strategy before these oyster reefs decline any further. The goal of this project was to develop a scientifically-based restoration technique that minimized wake damage from recreational vessels on intertidal reefs in Canaveral National Seashore. To accomplish this, I tested a range of restoration measures to identify a design that best increased: 1) oyster recruitment, 2) three-dimensional structure of the intertidal reefs, and 3) biodiversity and abundances of sessile and motile species associated with reefs. As a starting substrate in all treatments, I used restoration mats, which were created by affixing 36 drilled oyster shells to 0.4 x 0.4 m pieces of black mesh (Vexar). Five mats were deployed on the fore-reef, midreef, and backreef areas of each reef. In my experiment, I manipulated two habitat conditions: 1) leveling of existing dead margins to bring the top of the dead margin below mean high water to facilitate settling of larvae, and 2) deploying artificial seagrass seaward of the mats to act as a wake buffer. All combinations of these variables and all appropriate controls were replicated on six oyster reefs each, for a total of thirty reefs. Reefs that were leveled were significantly reduced in height and this difference was maintained throughout the 1 year study. Unleveled reefs actually increased in mean height over the 12 months. Tracking loose shells covering our restoration mats over time likewise documented that shell movement was minimal on control reefs lacking dead margins and significantly greater on reefs with dead margins. Midreef areas on reefs with dead margins were almost completely buried by loose shells. Quarterly monitoring of the number of spat settling on all restoration mats allowed for comparisons between treatments and locations on oyster reefs. After determining that overall water flow on the fore reef areas of all treatments was similar, I tested the null hypothesis that all treatments had similar recruitment of oyster larvae. My first alternative hypothesis was that artificial seagrass would increase oyster recruitment if the grass was a successful wake buffer and minimized sediment resuspension known to be lethal to newly settled oyster or prevented disarticulated oyster shell from moving and reforming mounds. My second alternative hypothesis was that the leveling of the dead margins would increase the total reef surface area available to larval oyster recruitment and thus lead to an increase in the number of recruits and eventually 3-dimensional reef structures (when oysters grow in close proximity and affix themselves together). Statistical analyses showed the artificial seagrass did not decrease the negative impacts caused by recreational boat wakes. Hence, it is not a recommended method for reef restoration. Recruitment of oysters significantly increased over time and significantly differed on various regions of the reefs. Recruitment was always highest on the fore-reef regions and lowest on back-reef regions. Although overall recruitment did not differ among treatments, it was significantly lower on midreef regions of the impacted reefs. This suggests that the leveling of the oyster reefs would increase the surface area available for future oyster recruitment. To look at biodiversity, I tested the hypothesis that all treatments would have similar biodiversity on a month by month basis. Alternatively, biodiversity should always be greatest on leveled reef with artificial seagrass due to increased 3-dimensional structure nearby and longer submersion times. To enumerate biodiversity, two lift nets were placed on each reef, one contained a restoration mat and the other contained only mesh (control). In most months, the four experimental treatments were similar according to the biodiversity measures analyzed. However, biodiversity was always higher in lift nets with restoration mats when compared to lift nets with mesh only. This result again suggests that the mats as designed are important restoration tools. Overall, my results show that placing seagrass in front of oyster reefs may not help to better restoration efforts. However, leveling dead margins on reefs and using the restoration mats is beneficial to oyster reef habitat restoration efforts. As a result of my research, restoration mats, in combination with leveling dead margins, are currently being used in a large-scale, community-based oyster reef restoration project within Canaveral National Seashore boundaries.

The extinct oyster Exogyra (Ostreoida: Gryphaeidae) thrived during the Cretaceous Period. The Genus was especially abundant in the southern parts of the United States, as these areas were once covered under a shallow sea. Left (lower) valves of the species Exogyra costata (Say, 1820), show different variations of the shells including differences in size and scarring of the scar remaining from the point of substrate attachment. The scars are often created by attaching to another organism, leaving an impression of it via a process called bioimmuration. This research analyses specimens from three sites within two different geological formations (Owl Creek Formation, Prairie Bluff Formation). Statistical analysis of attachment frequencies of collected specimens, as well as the analysis of the overall substrate availability reveals certain patterns of attachment, in addition to variations in lithologies of the study areas.

Vibrio parahaemolyticus is a Gram-negative, halophilic, human pathogenic bacterium ubiquitous in the marine environment. Like many Vibrio species, V. parahaemolyticus commonly associates with shellfish, particularly oysters. Ingestion of a raw or under cooked oysters contaminated with V. parahaemolyticus can cause gastroenteritis, which is typically self-limiting and rarely causes death. Globally, oyster production is highly lucrative, especially on the West Coast of the United States where approximately 60% of oyster production occurs each year. Outbreaks of V. parahaemolyticus can result in a significant public health problem as well as an economic burden for the oyster farms implicated in the outbreak. With the increase in overall V. parahaemolyticus outbreaks, improved post-harvest processing strategies have been developed to reduce this natural contaminant. Depuration was developed to allow shellfish to purge contaminants from their tissues into the clean, flowing seawater where they are held. This post-harvest processing technique can typically reduce fecal contaminants from the oyster tissues but is relatively ineffective at eliminating V. parahaemolyticus and other Vibrio species.. Thus, improved methods for reducing this and other human pathogenic Vibrio are needed to effectively produce safer oysters for the consumer. To develop more effective and novel V. parahaemolyticus intervention strategies, first we must identify the factors that are involved in V. parahaemolyticus colonization of the oyster, allowing them toresist depuration. This study sought to investigate specific factors utilized by V. parahaemolyticus and, in the process, determined that various strains of V. parahaemolyticus have different alleles of the Type IV pili, mannose-sensitive hemagglutinin (MSHA)and chitin-regulated pilus (PilA). In addition, we expanded our investigations into the allelic diversity of MSHA and PilA from Vibrio cholerae and Vibrio vulnificus and found that V. cholerae strains that possess the Type IV toxin co-regulated pilus (TCP) maintained highly conserved MSHA and PilA sequences while strains of V. cholerae without TCP, and all of the V. vulnificus and V. parahaemolyticus strains examined, had highly divergent sequences with no discernable connection to isolation source or observed phenotype. Following that discovery, we determined that Type I, and Type IV pili, as well as polar and lateral flagellar systems contribute to V. parahaemolyticus persistence in the Pacific oyster during depuration, while Type III secretion systems and phase variation do not. Overall, we have identified factors involved in colonization of the Pacific oyster by V. parahaemolyticus. Future studies investigating conditions that affect pili and flagella production in V. parahaemolyticus may provide novel depuration conditions that could easily and effectively increase the efficiency of oyster depuration, ultimately reducing the risk of seafood-borne illness by V. parahaemolyticus associated with oysters. / Graduation date: 2013

Thesis (M. Phil.)--University of Hong Kong, 1975. / Typewritten.

Thesis (M.S.)--Western Washington University, 2010. / Includes bibliographical references (leaves 104-115). Also issued online.

The microbial composition of Pacific oysters (Crassostrea gigas) subjected to UV-treated seawater was determined by quantitative and qualitative means. A total of 2,779 microorganisms were identified from seawater and oysters during a 72 hour sampling period employing a computer assisted replica-plating technique. UV treatment effectively eliminated coliforms and Pseudomonas Type I from seawater but other gram-negative asporogenous rods were more resistant. The microogranisms commonly found in oysters, whether subjected to UV-treated seawater or not, were, in the order of predominance, Pseudomonas Type III or IV, Vibrio/Pseudomonas Type II, Flavobacterium/ Cytophaga and Acinetobacter /Moraxella. The composition of microbial flora in oysters remained relatively stable irrespective of the microorganisms present in the seawater. A total of 18 presumptive hemolytic vibrios were found in oysters but further confirmation revealed two isolates to be Vibrio parahaemolyticas and the remainder Aeromonas species. Approximately 10 percent of the microorganisms isolated from seawater and oysters were gram-positive cocci and 14 to 23 percent of these were coagulase positive, DNase positive, and (β-hemolytic on human blood agar. / Graduation date: 1971

Coastal aquaculture is among the fastest growing sectors of the food producing industry. Bivalve farming is a promising activity in low income countries were mollusk could be cultured under low technology and budget, contributing to reduce poverty and assuring food security. Site selection has been considered as a key process in successful aquaculture developments. A suitability model for mangrove oyster farming in the PiraquC-aqu/PiraquC-mirim estuarine system - PAPMES (Espirito Santo, Brazil) was developed. The suitability model is based on Multi-criteria Evaluation (MCE) which consists of selecting criteria, define their acceptable and optimum ranges, assign their weights of relative importance, and combine suitability criteria under a decision rule. A georeferenced database was created with 8 water quality variables considered related to the habitat requirements of mangrove oyster, with 19 field sampling campaigns on 6 samplings sites embracing an area of 51 lha. Low salinity and dissolved oxygen levels were detected in the upper estuarine sections. Using the geographic information system (GIs) Idrisi32, point data were converted to continuous surface models using secondorder polynomial fit. The normalization process aimed at standardizing the set criteria considering a single scale ranging from low (i.e., 0) to high suitability (i.e., 255). Through pairwise comparison technique weights were assigned to each criteria. Salinity and dissolved oxygen were considered the most important criteria because of their relationship to oyster short-term survival. A weighted linear combination and two constraints (i.e., fecal coliform > 43 MPN1100mL and navigation channel) were applied as the MCE decision rule. An area of 75ha (14.6% of the PAPMES) was considered constrained for mangrove oyster fanning. Two suitability models were performed using average and low salinity values. Suitability maps developed onto the 0 - 255 range were reclassified in 4 categories: unsuitable, moderately suitable, suitable, and very suitable. In both models, no area was indicated as unsuitable. Although the low salinity model could be considered more restrictive, it yielded a very suitable area 26% larger than the average salinity model. The combination of the two models could bring together risk taking and risk-averse perspectives, respectively. The output of such combination is a map locating 80ha of very suitable areas for mangrove oyster farming, with 9.5ha preferentially designated for intertidal farming using racks. Aquaculture zones are discussed in terms of their interactions with other systems at higher spatial scales, such as the watershed and the coastal zone. GIs can serve as an integrative environment to integrate complex variables in multiple scales. It is only through its integration in multisectoral development plans and programs for the watershed and coastal zone realms that coastal aquaculture will be recognized as sustainable enterprise.