This study investigated the feasibility of ranching the abalone Haliotis rubra (Leach) and Haliotis laevigata (Donovan) on concrete artificial reefs at a site chosen by industry investors on silty bottom off Altona Beach, Port Phillip Bay, Victoria, Australia. The study started from the premise that artificial reef deployment combined with abalone stock enhancement may achieve the dual purpose of habitat and stock improvement. It evaluated the hydrodynamics of the site in relation to artificial reef structural stability and drift algal transport, the development and ecology of the artificial reef assemblage, and abalone enhancement by seeding the reefs with hatchery juvenile abalone and transplanting adult broodstock abalone. Despite a scarcity of reports on culturing abalone on artificial reef, a literature review examined broadly the functions of artificial reefs, particularly in the context of abalone enhancement, and the relationship between artificial reefs, hydrodynamics and ecology. The major finding was that the success of artificial reef projects is highly dependent on the environment of the chosen site, and that preliminary studies are essential to predict their likely success. This consideration alone provided strong justification to undertake this study. The topography at the Altona site was generally flat, with natural patches of low basalt boulder reef, offering low habitat complexity, yet supporting a diverse range of flora and fauna, including a low-density wild stock of H. rubra. Water depth was a mean of 3.3 m at low tide and 4.4 m at high tide. A single, uncomplicated, concrete artificial reef of H-shape design, was tested as abalone habitat. The hydrodynamic analysis confirmed previous studies of Port Phillip Bay, with mild current speeds of mean 0.045 m.s-1, and maximum-modelled wave height (H1/3) of 1.21 m and period (T1/3) of 4.51 sec. Water temperature ranged from 9.9ºC during July to 23.8ºC during January, with salinity averaging of 35.5 ppt. The site had a low probability of receiving drift algae, necessary as a food source for abalone, because of its geographic location, potentially affecting ranch productivity. Ecological monitoring of the three-year old artificial reef shows complex changes in the flora and fauna over time, particularly in respect of the sessile fauna. Key differences between the artificial reef and a nearby natural reef community were: lower cover of corallines and late colonisers, such as sponges. High levels of sedimentation were recorded at the Altona site. Hatchery juvenile H. laevigata, with mean survival of 15% after two years and a mean annual growth rate of 39 mm, showed the most promise for outplanting. In comparison, for hatchery juvenile H. rubra, mean survival was 9% after three years and mean annual growth rate was 22 mm. No natural recruitment of H. laevigata was recorded on artificial reef despite transplants of adult broodstock on the reefs. Natural recruitment of H. rubra was also low and insufficient to reliably contribute to abalone ranch stock. Having examined the hydrodynamic, ecological and enhancement attributes of the Altona site, the study concluded that the site was marginally viable for abalone ranching, and that an alternative site near Werribee, 20 km further southwest, had superior attributes for growth and survival of abalone.

In the marine environment, relatively little is known about how the effects of climatic change will manifest into future patterns of biodiversity and community stability, with the exception of recent work on corals in tropical reef ecosystems. In this thesis, I examine quantitatively how patterns of coral reef biodiversity will respond to the impacts of climatic change and provide essential information (i) to address a critical knowledge gap in the understanding of coral reef biodiversity and (ii) predict how a wide range of sessile invertebrates from coral reef ecosystems will respond to a range of potential impacts of climatic change such as increased physical disturbance and rising sea level. An initial descriptive component of my thesis was required to determine the distribution and abundance of a diverse assemblages of sessile non-scleractinian invertebrates, found along gradients of increasing physical disturbance from wave action and increasing intertidal shore height. I also examined the source, intensity and frequency of disturbance along these environmental gradients. This information was used to derive testable hypotheses about the potential impacts of increasing physical disturbance and rising sea level associated with climatic change. I found that physical disturbance had a substantial influence on the types of species that are able to survive in these intertidal rubble habitats, with diversity decreasing at more exposed shores and further down the shore. Physical disturbance was more important for determining the composition of sessile assemblages than other biotic factors such as predation, which only had weak effects on these sessile assemblages. Increased frequency and intensity of waves and storms will increase rates of physical disturbances such as scraping and overturning of rubble plates, which will have a substantial negative impact on biodiversity in these tropical intertidal habitats. These effects may be more complicated that first thought when combined with the effects of rising sea level which will not only alter the extent of inundation, but may also allow wave energy to propagate further up the shore, which has the potential to modify interactions among species through changes to the supply and recruitment of larvae, predator-prey interactions, competition and survival in harsher environments. However, the magnitude of these impacts may depend on how increased physical disturbance and rising sea level affect established species, and whether they will have a substantial effect on larval mortality rates, which currently appears to be limited by physical disturbance. Declines in biodiversity as a result of climatic change over the next 100 years could have important implications for the future health and productivity of coral reef ecosystems, especially given the ecosystem services these organisms provide. A greater understanding of the processes that drive the distribution and abundance of many different types of organisms on coral reefs, and indeed in other ecosystems, will provide essential information that managers can use to better understand and maintain these important ecosystems for future generations.

Macroalgae are an important part of the coral reef ecosystem that has largely been overlooked. However, in the past few decades their abundances have increased and this has been attributed to combinations of coral mortality opening up space in the reef, decreased grazing and increased nutrient load in reefs. This dissertation illustrates a novel means of investigating the effect of various growth and disturbance factors on the dynamics of macroalgae at three different levels (individual, population and 3-species community). Macroalgae are modular and clonal organisms that have differing morphologies depending on the environment to which they are exposed. These traits were exploited in order to understand the factors that were acting on the dominant and common macroalgae in the Florida Reef Tract: Halimeda tuna, Halimeda opuntia and Dictyota sp. The agent-based model SPREAD (SPatially-explicit REef Algae Dynamics) was developed to incorporate the key morphogenetic characteristics of clonality and morphological plasticity. It revolves around the iteration of macroalgal module production in response to light, temperature, nutrients, and space availability, while fragmentation is the source for mortality or new individuals. These processes build the individual algae then the population. The model was parameterized through laboratory experiments, existing literature and databases and results were compared to independently collected field data from four study sites in the Florida Keys. SPREAD was run using a large range of light, temperature, nutrient and disturbance (fragmentation without survival) levels and yielded six morphological types for Halimeda tuna, and two each for Halimeda opuntia and Dictyota sp. The model morphological types that matched those measured in two inshore patch reefs (Cheeca Patch and Coral Gardens) and two offshore spur and groove reefs (Little Grecian and French Reef), were formed in conditions that were similar to the environmental (light, nutrient and disturbance) conditions in the field sites. There were also differences between species in the important factors that influenced their morphologies, wherein H. opuntia and Dictyota were more affected by disturbance than growth factors, while H. tuna morphology was affected by both. Allowing for fragmentation with survival in the model resulted in significantly higher population abundances (percent cover and density). The highest abundances were achieved under high fragment survival probabilities and a high disturbance level (but not large fragment sizes). Incorporating fragmentation with survival and simulating the variations in light, nutrients and disturbance between the inshore patch reefs and offshore spur and groove reefs in SPREAD led to comparable abundances of Halimeda in the virtual reef sites. Adding competition for space and light and epiphytism by Dictyota on the two Halimeda species suggests that it can regulate the populations of the three macroalgae. However, comparing model abundances to the field, competition may not be a strong regulating force for H. tuna in all the sites and H. opuntia in the patch reefs. H. opuntia in the offshore reefs is possibly competitively regulated. Although SPREAD was not able to capture the patterns in the population abundance of Dictyota, this points to the potential importance of other morphometrics not captured by the model, a variation in growth curves between reef habitats, or the differential contribution of sexual reproduction.

<p>Coral reef fish coexist in a state of high diversity that has not been successfully explained by niche diversification, larval supply, differential mortality, or a suite of other proposed factors. These processes are all occurring on a diverse substrate that would be expected to affect the abundance and distribution of fish by directing habitat preferences as well as affecting competitive and predatory success. I conducted correlational studies on healthy and degraded Caribbean reefs that addressed fish abundances at the levels of community, species, and age class. I also experimentally tested habitat preferences in two ways: choice experiments on adults of common species that determined preferences for live coral and rugosity in an isolated environment, and monitoring of artificial reefs differing in live coral cover that tested habitat selection of adults and juveniles in the field. These observations all show that live coral had no effect on community parameters such as abundance or diversity, but that rugosity was positively related to species richness. However, these measures of the community masked differences at the species and age class level. A handful of species exhibited positive or negative preferences for live coral, but these selections did not follow a taxonomic or trophic-level classification. Species within the genus Stegastes, for example, could either aggregate towards or avoid live coral. One species even reversed its habitat preference as it matured. Field distributions were not determined solely by these habitat preferences, but inclusion of competitive interactions into a multi-factorial model explained distribution of some species. Results suggest that changes in live coral cover, an increasingly common phenomenon, would not affect fish at a community level, but could affect a few species through changes to recruitment or alteration of competitive interactions.</p> / Dissertation

The purpose of this study was to integrate the principles of marine geotechnical engineering, underwater acoustic and optical observation techniques into studying the distribution of seafloor sediments and engineering stability of artificial reefs off Yong-an Harbor, Kaohsiung County, south-western coast of Taiwan. The artificial reefs were deployed to the testing site in November 9th, 1996. The goal of this study was intended to describe the engineering status of this reef site and to investigate whether these reefs were moved and buried or not; as well as, to predict whether additional reefs should be deployed to this site in the future. Long-term monitoring of underwater targets was conducted by using of side-scan sonar system, echo sounder, sub-bottom profiler, and underwater video camera. The utility of side-scan sonar system was to depict the topography and terrain features of the seabed. The other equipments were used to complement and cross correlate the results of side-scan sonar observations. In this study, wave forces against reef were estimated by Morison¡¦s equation(ex. Huang, 1995), scouring depth was calculated by Silvester¡¦s experience equation (Silvester, 1974), and the settlement of reefs by theoretical consolidation equation(ex. Das, 1990). The topography of Yung-an reef site is generally gentle and monotonous. The major texture of surficial sediments in this site was sandy silt, and some gravel was distributed at the southern part of the site. In terms of the stability on the artificial reefs project, Typhoon was the main factor which causes the reef to slide or roll. Verified by theoretical analysis and monitoring, the study area of the original stacked reefs has tumbled during the research period, while the remaining non-stacked reef shows insignificant displacement and quantity of the settlement found no cases being buried. To sum up, Yong-an artificial reef district in Kaohsiung county, respectively as A, B, C; the stacked reef under normal condition has found no significant reef being buried and moving traces and artificial reefs can fully elaborate by the gathers of the fish. According to the viewpoint of this project , "Direct contact with the reef and the body of the sea-bed " both the forces of the waves and ocean currents when a typhoon strikes is not easy for the reefs to glide. The "stacked reef" which causes the reef to slide or roll when typhoon occurs was caused by both the forces of the waves and ocean currents. "Direct contact with the reef and the body of the sea-bed " in the case of wave period of 10 sec, analysis shows that the wave height must be greater than 5.8 m in order to make the reef slide. "Stacked reef" in the case of wave period of 10 sec, analysis shows that the wave height must be greater than 4.5 m in order to make the reef roll.

The purpose of this study is to incorporate the knowledge and technique of marine geotechnical engineering, underwater acoustic surveying and hydraulic experiment into studying the problems of artificial reefs off Ling-yang, Kaohsiung Country, South-western part of Taiwan deployed in March 1996. Based on hydraulic experiment, we try to observe the scouring mechanism of artificial reefs. Beside, two other reefs Yung-an, Fang-lio reef were surveyed in this study .The ultimate goal of this investigate was intended to deduce ways to solve the problem of excessive scouring and subsidence, and decide the appropriate environment of the seafloor to deploy artificial reefs for promoting fishing developing. The topography of Ling-yang is generally gentle. Based on the test of physics and mechanics, most surficial sediments at the surface was cohesiveless sand sediments including a lot of seashell. Therefore, we deduced that the surficial sediments are easier to drift caused by monsoon and typhoon in summer. The phenomenon indicated that the surface of sediments is unstable when the sediments are cohesiveless or were loaded by other forces. This study showed that there were obvious scouring effect occurred in and around the reefs, Ling-yang, Yung-an and Fang-lio. The most serious scouring area was occurred in Ling-yang, and a majority of reefs have been buried there. Therefore, the major factors, which could induce excessive subsidence or undermining of the artificial reefs in the testing site, were proposed to be scouring effects. Compared with other reef areas, the scouring effect was related to the grain distribution on the seafloor and the velocity of currents. In the aspect of preventing subsidence of reefs, the reefs closely deployed were better than that loosely deployed.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Ecology and Evolution." Includes bibliographical references (p. 73-77).

Thesis (M.S.)--University of North Carolina Wilmington, 2009. / Title from PDF title page (February 17, 2010) Includes bibliographical references (p. 63-67)

Thesis (M.S.)--University of North Carolina at Wilmington, 2003.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2002. / Restricted until October 2003. Bibliography: leaves 93-103.