Reefs, formation

Antonioli, R, Chemello, R., Improta, S. Riggio, S. 1999. Dendropoma lower intertidal reef formations and their palaeoclimatological significance, NW Sicily. Marine Geology, 161, 155—170. 

To understand the chemistry that underlies coral reef formation, we must understand the concepts of aqueous equilibria. In this chapter we take a step toward understanding such complex solutions by looking first at further applications of acid—base equilibria. The idea is to consider not only solutions in which there is a single solute but also those containing a mixture of solutes. We then broaden our discussion to include two additional types of aqueous equilibria those involving slightly soluble salts and those involving the formation of metal complexes in solution. For the most part, the discussions and calculations in this chapter are an extension of those in Chapters 15 and 16. 

Thorium isotope concentrations and ratios, as well as parent and daughter isotope concentrations, are used to date and study the formation and metamorphosis of rocks and sediments. For example, has been used to date coral reef terraces (4). / Th disequiUbria and Th/ Th... 

Where the waves and currents weaken, resuspended sediment settles back down to the seafloor. Given the small particle sizes of the suspended material (mostly 3 to 10 pm), redeposition can take many years. The resulting redistribution of sediments creates patches of clay, mud, and exposed rock on the continental margins. In other words, resuspension from waves and currents can cause some sediments to become reUct deposits. Hard bottoms can serve as good habitats for some members of the benthos as they promote the formation of coral reefs. For paleoceanographers, relict deposits are problematic because they represent gaps, or imconformities, in the sedimentary record. 

Palytoxin is a complex marine natural product containing 71 stereochemical elements (Fig. 5). The structure of PTX was elucidated by Moore. PTX is isolated from a zoanthid (order Zoanthidea) a type of soft coral commonly found in coral reefs all around the world. These animals come in a variety of different colonizing formations and in numerous colors. They can be found as individual polyps, attached by a fleshy stolon or a mat that can be created from pieces of sediment, sand and rock (soft coral). PTX is considered to be one of the most toxic nonpeptide substances known, second only to Maitotoxin. Typical symptoms of palytoxin poisoning are angina-like chest pains, asthma-like breathing difficulties, tachycardia, unstable blood pressure, hemolysis (destruction of red blood... 

Goreau, T. F., and Goreau, N. I. The physiology of skeleton formation in corals III. Calcification rate as a function of colony weight and total nitrogen content in the reef coral Manicinaareolata (Linnaeus). Biol. Bull. Ill, 420-429 (1959). 

It is believed that the presence of secondary metabolites impacts on the survivorship of a cyanobacterial strain in reef habitats that are subject to intense herbivory. Under suitable environmental conditions, cyanobacteria undergo rapid increases in population size, generating large cyanobacterial mats which are not calcified or of tough texture and which therefore present a potential source of food for herbivorous fish and other generalist predators. By restricting predation, potent cyanobacterial toxins facilitate the formation of cyanobacterial blooms.48... 

Vandermeulen J. H. and Watabe N. (1973) Studies on reef corals I. Skeleton formation by newly settled plaula larva of Poccillopora damicornis. Mar. Biol. 23, 47-57. 

The Ksp for calcium carbonate is 2.8 x 10 and the K value for calcium sulfate is 9.1 X 10. If coral polyps secreted calcium sulfate rather than calcium carbonate, how would this affect the formation of the coral reef ... 

Shallow marine environments include coral and algal reefs as well as other bioherms and many favour calcification by benthic fauna. Stromatolites and stromatolitic environments are also typical shallow marine formations. The shallow marine carbonate environment may be subdivided into more or less agitated waters with dominantly benthic fauna, calm shallow areas with carbonate muds (e.g. Bahama Banks) with ooids as typical forms of deposits and reef areas with their complicated patterns of calcification and deposition (Bathurst, 1975 Kinsey and Davies, Chapter 2.5). 

Davies, P.J. and Kinsey, D.W., 1973. Organic and inorganic factors in beach rock formation, Heron Island, Great Barrier Reef. J. Sediment. Petrol., 43 59—81. 

Goreau, T.F. and Goreau, N.I., 1959b. The physiology of skeletal formation in corals. II. Calcium deposition by hermatypic corals under various conditions in the reef. Biol, Bull., 117 239—250. 

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