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Summary
Published in Stephen A. Bortone, Shinya Otake, Modern Fisheries Engineering, 2020
Stephen A. Bortone, Shinya Otake
In Southeast Asia, artificial reefs are often constructed using locally grown vegetation. These reefs provide habitats and are utilized to facilitate fish harvests that subsequently help build a local fishing economy. While still in various stages of development and improvement, the technology involved is necessarily fairly primitive. Jani (Chapter 6) foresees a future for Fisheries Engineering, especially as it pertains to artisanal artificial reefs, that includes involvement of a broader range of stakeholders to achieve fishery management solutions. Thus, merging the knowledge base known to users with the information and analytical expertise of scientists and resource managers will produce the best solutions.
Biomaterials and Bioprocesses of Construction Biotechnology
Published in Volodymyr Ivanov, Environmental Microbiology for Engineers, 2020
An important application of calcium carbonate biocoating could be the construction of artificial coral reefs. Coral reefs are declining and degrading around the world due to the anthropogenic pollution of water and the acidification of seawater due to global climate change. Creation of artificial reefs with a structure suitable for coral larvae and symbiotic microscopic algae to grow on is considered an effective way for the restoration of damaged coral reefs to maintain marine biodiversity and productivity as well as for recreational fishing and diving.
Coral Reef: Biology and History
Published in Yeqiao Wang, Coastal and Marine Environments, 2020
Coral reefs are biogenic habitats, so called because these rocky reefs that rise from the seabed are built by living organisms. The calcium carbonate skeletons deposited by growing corals and calcareous algae gradually accrete reefs that can form enormous limestone landscapes underwater.6,7 Reef-building corals and algae are, therefore, called “ecosystem engineers”8 because they create a place to live for so many other species. Coral growth rates are highly variable, e.g., the linear extension rate of two major Caribbean corals ranged from 0.6–0.9 cm/year for Montastraea annularis and 5–10 cm/year for Acropora palmata.9 Some corals form growth rings in their limestone skeletons as they grow, much like tree rings.10 These growth rings can be used to age coral colonies and reveal that colonies of slow-growing corals can live for hundreds of years. Reef growth is also fostered by the deposition of calcium and silica from sponges, which, along with calcareous algae also have an important role in cementing the various calcium carbonate skeletal deposits into a solid coherent matrix.6
Identifying the pore structure and permeability anisotropy of coral reef limestone based on CT image analysis
Published in Marine Georesources & Geotechnology, 2023
Junpeng Wang, Xin Huang, Jun Xu, Shuaifeng Wang, Guolong Jin, Zixin Zhang
Coral reef formations are widely distributed in the Indo-Pacific region with latitudes between 30°N and 25°S (Nakamori, Iryu, and Yamada 1995; Bai et al. 2010). These formations are mainly composed of coral reef limestone, which is a special rock type formed by the long-term sedimentation of coral worm carcasses and the remains of a few other marine organisms (Deshmukh et al. 1985; Spencer and Viles 2002). The combination of the marine environment, climatic conditions, and specific rock-forming process creates this special limestone, which is overwhelmingly different from the inland normal limestone. Due to the recent thriving of ocean exploration, coral reef limestone has become a major concern for coastal project construction and offshore resource development in tropical and subtropical regions (Zhao, Song, and Lu 1996; Ren et al. 2015; Zhu et al. 2017).
Assessment to 2100 of the effects of reef formation on increased wave heights due to intensified tropical cyclones and sea level rise at Ishigaki Island, Okinawa, Japan
Published in Coastal Engineering Journal, 2021
However, the world’s coral reefs are now degraded by global climate change, including elevated sea-surface temperature (SST) and ocean acidification, and by local impacts, including sedimentation, coastal development, and watershed pollution (Burke et al. 2011; Gattuso, Hoegh-Guldberg, and Pörtner 2014). In particular, losses of coral cover cause a decrease in reef bottom roughness and wave dissipation (Sheppard et al. 2005). This indicates that losses of coral cover will increase the risks of coastal damage by intensified TCs by 2100. However, sedimentological and biological studies have shown that corals have kept pace with sea level rise (SLR) at a rate of <10 m/kyr (1 kyr = 1000 years) and reef formation has occurred during the last postglacial period (Montaggioni and Brainthwaite 2009; Woodroffe and Webster 2014). This implies that reef formation may be able to respond to future global SLR by 2100. Therefore, a quantitative study evaluating the effectiveness of coral reefs in the context of intensified TCs, decline of corals, and SLR by 2100 is needed. If future coral reefs are degraded due to various stresses, reef restoration and conservation strategies (e.g. direct coral transplantation) will be considered. For the effective strategies, the target coral species will be also identified.
Wave-induced set-up over barrier reefs under the effect of tidal current
Published in Journal of Hydraulic Research, 2020
Yu Yao, Wenrun He, Changbo Jiang, Ruichao Du
Coral reefs deliver ecosystem services to tourism, fisheries and shoreline protections. Barrier reefs are one of the most common types of coral reef. A typical cross-shore one-dimensional horizontal (1DH) barrier reef profile can be characterized by a steep offshore fore-reef slope, an inshore shallow reef flat and a deep lagoon (Gourlay, 1996). There is also possibly a reef crest lying at the reef edge (e.g. Hench, Leichter, & Monismith, 2008). Most corals only live within a limited depth range, starting just below low tide, thus they may impose a shallow water control on the waves reaching reef flats. Similar to the wave transformation over a shallow shelf, ocean waves first shoal on a fore-reef slope and then break near the reef edge, dissipating their energy and generating a rise of mean sea level known as “wave set-up”, a phenomenon first described by Munk and Sargent (1948). The maximum set-up usually occurs on the reef flat where wave breaking ceases, and it can drive a flow across the shallow reef flat, through the deeper lagoon, and finally the flow exits to the open sea through a rip channel, thus building up a two-dimensional horizontal (2DH) regional circulation in the reef area (Lowe, Falter, Monismith, & Atkinson, 2009), which is crucial to the transport of organisms, nutrient and sediments (Hench et al., 2008). Therefore, wave set-up has aroused wide attention in the coral reef hydrodynamics research community.