Algae calcium carbonate

Schnitzler I, Boland W, Hay ME (1998) Organic sulfur compounds from Dictyopteris spp. deter feeding by an herbivorous amphipod (Ampithoe longimana) but not by a herbivorous sea urchin (Arbaciapimctulata). J Chem Ecol 24 1715-1732 Shen Y, T sai PI, Fenical W, Hay ME (1993) Secondary metabolite chemistry of the Caribbean marine alga Sporochnus bolleanus. a basis for herbivore chemical defense. Phytochemistry 32 71-75 Schupp PJ, Paul VJ (1994) Calcium carbonate and secondary metabolites in tropical seaweeds variable effects on herbivorous fishes. Ecology 75 1172-1185 Smit AJ (2004) Medicinal and pharmaceutical uses of seaweed natural products a review. J Appl Phycol 16 245-262... 

Platform carbonates Massive concretions of calcium carbonate in neritic sediments deposited by corals, corraUne algae and other organisms that deposit calcareous hard parts. 

Biomineralization, 36 137-139 calcium carbonate, 36 163-167 in algae, 36 166-167 gravity sensors, 36 164-166 carbonate/sulfate mineralization mechanisms, 36 171-175... 

Emiliania huxleyi is a unicellular alga which is surrounded by a number of loose oval discs of calcium carbonate (coccoliths). It has been shown that the CaC03 of the... 

STROMATOLITE. A term that has been generally applied to variously shaped (often domal), laminated, calcareous sedimentary structures formed in a shallow-water environment under the influence of a mat or assemblage of sediment-binding blue-green algae that trap fine (silty) detritus and precipitate calcium carbonate and that commonly develop colonies or irregular accumulations of a constant shape, but with little or no... 

Goreau, T. F. Calcium carbonate deposition by coralline algae and corals in relation to their roles as reef-builders. Ann. N. Y. Acad. Sci. 109, 127—167 (1963). 

Paul, V. J., Secondary metabolites and calcium carbonate as defenses of calcareous algae on coral reefs, Proc. 8th Int. Coral Reef Symp., 1, 707, 1997. 

Nature is full of complex constructions designed to encapsulate molecules within a defined space. At one extreme there are cells, enclosed within phospholipid bilayers, and sea dwelling algae like Emiliania huxleyi that are surrounded by calcium carbonate coccoliths which overlap to form an exoskeleton. On a smaller scale are iron storage proteins such as ferritin that are amorphous in the absence of metal ions but form globular structures once metals are bound. 

Extracellular calcium carbonate formation by some cyanobacteria and algae, which are photo synthetic autotrophs that obtain their carbon from CO2, can be explained by Eq. (1.5) above. In that instance, the uptake and fixation of CO2 by the cyanobacteria and algae promotes C03 formation needed for precipitation of extracellular CaC03. In the cyanobacterium Synechococcus, the Ca precipitated by C03 from photosynthesis is derived from that bound to the cell surface of Synechococcus (Thompson et al., 1990). 

The most actively cycled reservoir of carbon is atmospheric C02 (it constitutes 0.034% of the atmosphere). Carbon dioxide dissolves readily in water and is in direct equilibrium with dissolved inorganic forms of carbon (H2C03, HCO, and CO7-, see Section 6.2.1.3). Once there, it may precipitate as solid calcium carbonate (limestone). Corals and algae encourage this reaction and build up limestone reefs in the process, but a much larger portion in the deep sea equilibrates only at the slow rate of... 

Calcium carbonate minerals (CaCOs) are ubiquitous in biomineralizing systems, since they are in the skeletons of organisms ranging from bacteria and algae to humans, most commonly as calcite (rhomboedral) or aragonite (orthorhombic). Thus, their structures and compositions are highly diversified. Here, only some examples are discussed. 

Calcium carbonate minerals are deposited in a wide variety of bacteria, protozoa, algae, higher plants, and invertebrates (Table I). They are also formed, although not as frequently, in vertebrates. The major structural polymorphs identified in biological systems are calcite, aragonite, and vaterite, although there is also evidence for monohydrate, amorphous, and a range of Ca/Mg carbonate phases. 

Sedimentary calcium carbonates are formed as the shells of marine plants and animals. Biologically produced CaCOs consists primarily of two minerals aragonite and calcite. Shallow-water carbonates, primarily corals and shells of benthic algae (e.g. Halimeda) are heterogeneous in their mineralogy and chemical composition but are composed mainly of aragonite and magnesium-rich calcite (see Morse and Mackenzie (1990) for a discussion). Carbonate tests of microscopic plants and animals, most of which hve in the surface ocean (there are also benthic animals that produce carbonate shells), are primarily made of the mineral calcite, which composes the bulk of the CaCOs... 

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