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Coral Reef: Biology and History
Published in Yeqiao Wang, Coastal and Marine Environments, 2020
Charles Darwin16 devised a simple and enduring classification of reefs, dividing them into fringing reefs, barrier reefs, and atolls. Fringing reefs grow on the sloping perimeter of most tropical islands and along many coastlines. Here, corals colonize rocky substrata and form a layer of reef that grows upward toward the water’s surface and may spread offshore if conditions permit. Barrier reefs, in contrast, are separated from the coastline or island landmass by a lagoon at least 10 m deep and typically 1–10 km wide. The best known examples are the world’s two largest reef systems, the Great Barrier Reef (over 2,900 reefs spanning 2,600 km off the coast of Australia) and the Mesoamerican Barrier Reef (stretching roughly 1,000 km from Mexico to Honduras). Another reef type, not classified by Darwin, is the patch reef, which as their name suggests grow as small isolated outcrops within lagoons. The third of Darwin’s reef types is the atoll, which is a ring of reef that surrounds a lagoon. Underlying the lagoon is a volcanic basement. Atolls originally develop as fringing reefs around volcanic islands. Over time, as the island gradually collapses or sea level rises, the ring of reef is eventually all that remains.
Kiribati and Climate Change
Published in Cameron La Follette, Chris Maser, Sustainability and the Rights of Nature in Practice, 2019
His Eminence Anote Tong, Cameron La Follette, Chris Maser
The Republic of Kiribati, formerly known as the Gilbert Islands and a former colony of the United Kingdom, comprises three groups of 33 atoll islands scattered astride both the Equator and the International Date Line. It has the distinction of being the only country to occupy the four corners of the globe. Inclusive of its 200-mile (322-kilometre) Exclusive Economic Zone, it covers 1.3 million square miles (3.5 million square kilometres) of the centre of the Pacific Ocean, in contrast to its total landmass of just over 800 square kilometres (309 square miles). Atoll islands are coral islands that form atop submerged seamounts, typically aligned as a string according to the movement of the tectonic plate where they are located and the hotspots beneath the plate, which burn through the plate to form the seamounts. The islands are narrow strips of coral sand surrounding a lagoon, and are low lying, on average rising no more than 2 metres (6.5 feet) above sea level.
Giant Clams (Bivalvia: Cardiidae: Tridacninae): A Comprehensive Update of Species and their Distribution, Current Threats and Conservation Status
Published in S. J. Hawkins, A. J. Evans, A. C. Dale, L. B. Firth, D. J. Hughes, I. P. Smith, Oceanography and Marine Biology, 2017
Mei Lin Neo, Colette C.C. Wabnitz, Richard D. Braley, Gerald A. Heslinga, Cécile Fauvelot, Simon Van Wynsberge, Ser.G.E. Andréfouët, Charles Waters, Aileen Shau-Hwai Tan, Edgardo D. Gomez, Mark J. Costello, Peter A. Todd
At national and local (archipelago, island, reef) scales, giant clam conservation management has focused on fishing regulations and restocking (see previous sections). Assessing the effectiveness of such conservation efforts for a particular location requires an understanding, and ideally modelling, of processes and factors that influence their distribution and abundance. These include aspects of the species’ biology, population dynamics (e.g. size-structure, density, recruitment, mortality), life-history traits (e.g. growth-fertility, reproduction and spawning occurrences) (Apte & Dutta 2010, Black et al. 2011, Yau et al. 2014, Dolorosa et al. 2014, Neo et al. 2013b, 2015b, Menoud et al. 2016, Van Wynsberge et al. 2017), and larval flux (Neo et al. 2013a). Human uses and impacts are also important factors to consider (Van Wynsberge et al. 2015, 2016). Recently, mass mortality in semi-enclosed atolls due to unusual physical oceanographic conditions has been identified as a key driver of population dynamics (Andréfouët et al. 2013) and climate change is likely to make these events more frequent (Andréfouët et al. 2015). These examples highlight the importance of monitoring physical conditions and their integration into models (Neo et al. 2015b, Van Wynsberge et al. 2017). Finally, but this has never been attempted, an ecosystem-based characterization including spatio-temporal variation in predation, competition, and food availability, is also likely to influence the accuracy of models simulating the effectiveness of conservation measures.
Distribution of Cu fraction in sediments using Suaeda heteroptera - Nereis succinea combination: A greenhouse study
Published in International Journal of Phytoremediation, 2019
Jie He, Qingzhi Wang, Xiaotong He, Xu Chen, Changfa Liu, Yibing Zhou
At present, the continental and marine ecosystems are subjected to excessive metal contamination due to the progressive industrial growth and increase in population. (Jayaprakash et al. 2015). Metals sources to the aquatic regions are mostly brought in by industries, house hold sewages discharge and atmospheric deposition, geological weathering and run-off from adjacent agricultural lands as natural discharge (Mansour et al. 2013; Monroy et al. 2014). Fujita et al. (2014) reported heavy metal contamination occurred in coastal lagoon sediments of the Pacific atoll that there were significant contamination of coastal sediments with chromium (Cr), zinc (Zn), copper (Cu), lead (Pb) and cadmium (Cd) due to domestic wastewater discharge. In China, heavy metal pollution in Bohai Bay, the Yangtze River Estuary and the Pearl River Estuary were serious, with the most important pollutants being Cd, Cu, Zn, Pb and Cr, and they had reached ecologically harmful levels (Chu et al. 2008; Qin et al. 2008; 2012). Even when the essential metals for our lives are above certain concentrations, it can bring toxicity to organisms (Merciai et al. 2014). Heavy metals in aquatic environments had studied because of their toxicity, persistence in the environment, and subsequent accumulation in the bodies of aquatic microorganisms, flora and fauna, which may, in turn, enter the human food chain and cause a host of health problems (Guan et al. 2016; Yi et al. 2011; Zhang et al. 2014). In order to take measures to protect aquatic ecosystem, it is necessary to assess the heavy metal contamination in sediments. The biological toxicity of heavy metals is not only related to their total amount, but also to their chemical fractions in a certain degree, and different fractions will make different impacts on the environment (Petit et al. 2009; Rodríguez et al. 2009; Wang et al. 2002; Zheng and Zhang 2011). Accordingly, the determination of Cu fractions in sediment is of primary concern in assessing its behavior in the environment.
Of fission and fallout: New Zealand in the nuclear age
Published in Journal of the Royal Society of New Zealand, 2021
Measurements were made on 432 islands of the 29 atolls and 5 islands that make up the Marshalls group Over 90% of the radiation dose rate from fallout is attributable to caesium-137. Figure 2 shows the maximum concentration (Bq/m2) of Cs-137 measured in soil at each atoll plotted as a function of latitude.