Home / Charophyceae / Chara
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Name derivation:
"Graceful" -- Charaties - the three graces (Gr.) Chara is commonly called “muskgrass” (because of its odor) or “stonewort” (because of the deposition of marl on its epidermis).
Classification:
Chara Linnaeus 1753; 240 of 1,194 species descriptions are currently accepted taxonomically (Guiry and Guiry 2013). Order Charales, family Characeae Synonym in PhycoKey: Lamprothamnion.
Morphology:
Chara is a green branched “charophyte” attached to the sediment with branching underground rhizoids. They are likely predecessors of mosses but lack adaptations to living above water. Superficially the ~18 species resemble terrestrial plants because of stem-like and leaf-like structures. Branches are derived from apical cells that form segments at the base to form nodal and internodal cells. The cells feel coarse (rough to touch) because of deposited “marl” (calcium carbonate) on the cell wall. CaCO3 is only slightly soluble in water. At pH levels higher than ~8, the equilibrium of inorganic carbon shifts from the more soluble bicarbonate (HCO3^-) ion to the less soluble CO3^= ion, and precipitates as marl in “hardwater” lakes. In lake water with low salinity at 20 C the maximum Ca^+2 concentration is 7.2 mg L^-1 at pH 7, and only 0.072 mg L^-1 at pH 8. Photosynthesis removes dissolved CO2 and can release OH^-1 directly driving pH upward. In the microzone immediately outside Chara cells marl forms and remains attached to the cell walls. Chara species often become thickly coated with the white marl, more so than aquatic vascular plants. The mass of marl often becomes greater than that of the organism (Wetzel 1960). The large intermodal cells, among the largest of cells that occur in protists and plants, have rapid cytoplasmic streaming easily observed at a magnification of x100 – x400. The rate of streaming has been measured at up to 50 µm per second, with a motive force requiring ATP and involving bundles of microfilaments. It has been proposed that Chara contains both actin and a myosin-like protein, and that the cytoplasmic streaming is similar at the molecular level to animal muscle contraction and relaxation, but at a much lower concentration of cellular calcium ion (Ca^+2) (Williamson 1975). Gravity sensing (gravitropism) by Chara has been demonstrated by placing vertically-oriented intermodal cells in media with higher density, that reverses the direction of streaming. A model is proposed that involves peptides at the ends of the cells, activation of calcium channels, and induction of polarity (Staves 1997). Sack (1996) presents evidence that gravitropism in Chara as well as in land plants involves sedimentation of amyloplasts and is plastid based, rather than a more diffuse whole-cell involvement.
Similar genera:
Nitella, a related charophyte, is less coarse and appears to outcompete Chara in softwater lakes (low calcium concentration).
Phytoremediation:
Chara algae transforms 42-49% of PAHs (polycyclic aromatic hydrocarbons) which has an important role in the fate of carcinogenic PAHs in the environment, therefore the Chara has the ability to extract the carcinogens out of the water supply and into their system, to help lower the abscess of carcinogens in the environment (Kirso and Irha, 2010). An ecofriendly and non-destructive method of dye removal from water and soil. Chara vulgaris is used for biological treatment of Congo red dyes (Mahajan and Kaushal, 2013). As well as the biological decolorization of Malachite green dye with Chara sp. (Khataee et al. 2010).
Habitat:
Lakes with moderate to high alkalinity. Chara often is covered with marl due to photosynthetic increase in pH. Sediments produced by years of massive growth of Chara are concretions of marl (CaCO3) precipitate.
Repulsion of Daphnia:
Metabolic processes often give Chara plants a distinctive smell of H2S (hydrogen sulfide). Chara and Nitella release organic secondary metabolites analogous to substances derived enzymatically from garlic oil, called allyl sulfides or sulfoxides (reviewed by Hutchinson 1975). Mosquitoes and several groups of zooplankton including Daphnia are strongly repelled by these macroalgae. as well as by the submerged vascular plants Elodea and Myriophyllum (reviewed by Wetzel 2001). Perhaps this is an element of shoreline avoidance (‘Uferflucht’) by zooplankton thought to be triggered mainly by shadow avoidance (Siebeck 1968).
References:
Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 22 May 2013. Hutchinson, G.E. 1975. A Treatise on Limnology. III. Limnological Botany. Wiley and Sons. (660 pp.) Khataee, A.R., G. Dehghan, E. Ebadi, M. Pourhassan 2010. Central Composite Design Optimization of Biological Dye Removal in the Presence of Macroalgae Chara sp., Clean-Soil, Air, Water. 38:750-757 Kirso, U., and N.Irha 2010. Role of Alga in Fate of Carcinogenic Polycyclic Aromatic Hydrocarbons in the Aquatic Environment. Ecotoxicology and Environmental Safety. 41:83-89 Linnaeus, C. 1753. Species plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Vol. 2 pp. [i], 561-1200, [1-30, index], [i, err.]. Holmiae [Stockholm]: Impensis Laurentii Salvii. Sack, F.D. 1996. Plastids and gravitropic sensing. Planta 203:563-568. Siebeck, O. 1968. "Uferflucht" und optische Orientierung pelagischer Crustaceen. Archiv für Hydrobiologie. Suppl.-Band, XXXV(1): 118 p. Staves, M.P. 1997. Cytoplasmic streaming and gravity sensing in Chara intermodal cells. Planta 203:579-584. Wetzel, R.G. 1960 Marl encrustation on hydrophytes in several Michigan lakes. Oikos 11:223-236. Wetzel, R.G. 2001. Limnology: Lake and River Ecosystems. Academic Press (3^rd edition, 1,006 pp.). Williamson, R.E. 1975. Cytoplasmic streaming in Chara: A cell model activated by ATP and inhibited by cytochalasin B. J. Cell Sci. 17:655-668.