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Shellfish reefs have been an ecological, economic, and engineering resource since the early 1800s, with numerous species of oysters representing a key resource for fishing activities. Due to overexploitation, shellfish reefs are now considered at risk, as are the ecosystem services they guarantee. For this reason, more and more shellfish reef restoration projects are being implemented in the United States, Europe, and Australia. In South Australia there are currently four shellfish reef restoration projects, the Windara Reef in the Yorke Peninsula, the Glenelg Shellfish Reef in Adelaide, and two incomplete oyster reefs in O'Sullivan Beach and Kangaroo Island. Some of the above-mentioned countries, shellfish reef restoration projects have proved to be a sustainable and successful method, not only for the conservation of local species and their biotic and economic importance, as well as for coastal environments. However, it is important to analyse how reefs affect the hydrodynamics of the adjacent environment, in order to evaluate the performance of the structure, regarding its role on potential coastal protection. The current study developed a Delft3D numerical model to estimate the capability of the Glenelg shellfish reef in relation to potential wave energy dissipation, significant wave height reduction and attenuation of wave-driven currents. Furthermore, a two-days FLOW module testing was simulated to highlight the influence of the Glenelg reef on tidal currents and bed shear stress. The obtained results showed a minimal ability of the current reef, to influence the hydrodynamics of the area, with bigger effects during storm periods. The numerical model was subsequently validated by comparing the obtained results with wave data collected by SA Water with a pressure sensor. The validation process showed the ability of the model to pick up the wave trend, mostly during the days defined as "calm" (lower significant wave height), while it showed an overestimation of the data during the days defined as "storm" (higher significant wave height).
The goal of this project was to determine the effects of oyster reef restoration on oyster coverage, wave height dissipation and seagrass recruitment. First, to assess the current versus historical coverage of natural, dead and restored oyster reefs within Mosquito Lagoon, aerial photographs from 2009, provided by Saint Johns River Water Management District, were digitized using ArcGIS software. Live reefs, restored reefs and dead reefs were screen digitized using a reef 'signature' in order to estimate the area of each type of reef. The 2009 maps were used as a guide to digitizing the historical aerial photographs (1943, 1951, 1967, 1971, 1984, 1995, 2006). Dead reefs increased both in number and aerial extent during the study period (1943-2009), with 2009 having over 10 acres of dead reef coverage. Dead reefs were more likely to be found along major boating channels. Several dead reefs exhibited migration into the mangrove islands located landward of the 1943 footprint, with some dead reefs completely washing up into the shoreline. Restoration of dead reefs added 0.5 acres of live oysters to the Mosquito Lagoon area as of January 2009. Second, I examined how different oyster reef types (natural reef, restored reef, dead reef) reduced wave height. To determine wave height attenuation on each reef type, experiments were conducted in a 9 meter long wave tank using sensors that measured changes in wave height. For each reef type, replicate reefs were created in the wave tank. Shoreline sediment without oysters was used as a control. Using the wave generator, wave heights similar to Mosquito Lagoon boat wakes were created. Restored reefs reduced the incoming wave height by 25% compared to sediment without oysters. Lastly, I examined the potential link between oyster reef restoration and recruitment of seagrass fragments. Monthly surveys were performed to quantify the number of seagrass fragments encountering the three oyster reef types: dead reefs, natural reefs and restored reefs. The quantity of seagrass fragments was found to be similar on the three different reef types, but did show a significant trend of seasonality, which corresponds with the growing season of Halodule wrightii. Next, I tested retention of experimentally manipulated seagrass fragments on five natural and five restored reefs. Restored reefs retained seagrass fragments for significantly longer than natural reefs. I also measured seagrass fragment entanglement on each reef type inside the wave tank. I found that seagrass fragments were significantly more likely to become entangled and retained on restored reefs compared to dead and natural reefs. Overall, these metrics are important for determining the success of long-term oyster restoration project in Mosquito Lagoon, Florida. This project has found that oyster restoration is increasing the area of oyster habitat as well as providing important ecosystem services.
The structure of coastal communities varies spatially and temporally in response to abiotic and biotic stressors. Local environmental conditions can be modified by the presence of a foundation species, whose dominant physical presence facilitates the growth of other organisms by ameliorating stress, providing settlement substrate and increasing resources. Oyster reefs (Crassostrea virginica) are an important foundation species found in estuarine environments. Oyster reefs form three-dimensional, structurally complex, biogenic habitats, that modify sediment and wave dynamics and ameliorate stress for community associates. Furthermore, they also act as a form of green-infrastructure, decreasing erosion rates and preventing shoreline loss. Because of their numerous benefits, efforts have been made to restore oyster reefs globally, with varying levels of success. Variability in the success of these restoration projects may be due to a lack of understanding of the abiotic and biotic factors that govern reef ecology. To better understand how abiotic and biotic processes regulate intertidal oyster reef community structure and their effects on restoration, we investigated the following research questions: 1) How does wave energy below 500 J/m affect oyster abundance? 2) How does reef crest height affect oyster abundance? 3) How does wave energy mediate oyster consumption? 4) How does reef relief mediate consumption of oysters? Oyster breakwaters of two different reliefs (high vs. low) were constructed to assess how reef relief affects oyster abundance. Wave gauges were built and deployed to monitor the local wave energy environment at each site. A manipulative field experiment was used to quantify consumption with different relief and caging treatments. Results suggest that constructing reefs with high vertical relief significantly increases oyster abundance. However, the interaction between reef crest elevation and wave energy can modify this relationship, causing site-level differences in oyster abundance. Furthermore, juvenile oyster consumption was not dictated by relief and instead was site specific, most likely due to differences in predator identity at each site. This suggests that when reefs attain high oyster densities, they can support numerous community associates. The accumulation of high oyster densities on an alternative reef material, like OysterCatcher(TM) material, suggests that this substrate is suitable for future oyster restoration projects. However, practitioners and researchers must be aware of the effects of environmental factors such as wave energy when restoring reefs. Further research is needed to understand how human changes to the environment, such as altered wave energy due to high boating traffic, interacts with design characteristics and reef ecology to impact restoration successes and failures.
The restoration of habitat has become a priority for many citizens and governments as the ecological and societal benefits of these habitats have been become more widely recognised. This publication is intended to provide foundational information to serve as a useful starting pointfor shellfish reef restoration.
The coast is one of our most valuable assets but how is it being treated and what is being done to look after it? COASTAL MANAGEMENT IN AUSTRALIA is the first book to provide a comprehensive overview of this important subject. Interesting case studies are used to illustrate human impact on coastal processes as well as demonstrating the global significance of the coast and the international imperative to manage it properly. COASTAL MANAGEMENT IN AUSTRALIA introduces the background to the various coastal management systems operating in Australia and illustrates these with 'real world' examples from the different states and territories. Since this book was first published yet another parliamentary inquiry has been added to some 30 years of national inquiries into coastal management, with further calls for national co-ordination. In addition, the Australian government has focused attention on the potential risks of climate change for the Australian coast. Both authors have national and international coastal expertise; significant academic teaching experience in coastal processes and coastal management; coastal planning and policy skills; and have extensive government expertise in coastal management.
At the coast all is not what it seems. Decades of beachfront development have seen a variety of efforts to stabilize the shoreline to protect ill-placed beachfront property, both from shoreline erosion and from storm damage. Both of these problems become increasingly critical in a time of rising sea level. Many natural beaches are backed by sea walls, while others have been transformed by whole series of groynes, offshore breakwaters and a plethora of other schemes. Many recreational beaches are actually artificial replicas of the real thing, emplaced to protect badly placed infrastructure and maintained only through ongoing costly beach nourishment. However, all of these attempts to stabilize the shoreline are far from benign. Degradation and even complete loss of the all important recreational beach sometimes results from seawall emplacement. Increasingly, the choice of shoreline stabilization approach will depend upon plans for future response to rising seas which in many cases may involve retreat from the shoreline rather than holding the line. This book explores, through a series of case studies from around the globe, the pitfalls of shoreline stabilization and provides a ready reference for those with an interest in shoreline management. It is particularly timely in a time of global change.
Cancer doesn't discriminate. When things were at their worst for Jarryd Roughead, his four premierships, two All-Australian gongs and a Coleman Medal counted for nothing. As he spent his days vomiting or curled up with the cat, and his nights in a pool of sweat, fully clothed yet freezing, rolling out of bed every couple of hours to dunk his feet in cold water to douse the feeling that they were on fire, all that mattered was that he didn't stop believing. Roughead knew he had to keep believing he'd get better, otherwise he'd lose. And if he lost this battle, there would be no next week. "Roughy" is the story of a footballer who lived the dream, the country boy who not only became an AFL star, but was a key player in a Hawthorn team that will be remembered as one of the greats of any era. In 2015, a spot on his bottom lip was diagnosed as melanoma and it returned as spots on his lungs the next year. In "Roughy", you'll discover the resilience that got him through horrendous immunotherapy and helped him to not only play AFL again, but as Hawthorn captain. You'll read the stories of his childhood, of the basketballer who switched sports and learned not just to believe, but to expect to be the very best. Of his love for Sarah and their daughter Pippa, his unwavering will to carry on, his dignity through a final chapter of his career that was dignity personified, with a fairytale ending that was celebrated by all.