Home / Diatoms / Pennate / Colonies / Araphes / Asterionella
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Name derivation:
"Little Star" -- Star Aster- little –ionella
Classification:
Asterionella Hassall 1850; 8 of 53 species descriptions are currently accepted taxonomically (Guiry and Guiry 2014). Order Fragilariales; Family Fragilariaceae
Morphology:
Star-shaped colony often has six to eight cells glued together valve-face to valve-face at one end, and at the center of the flat colony. During rapid growth at the beginning of a population pulse the colony may accrete many more cells in more of a spherical configuration. During population demise the colonies tend to dissemble into groups of two or three cells. Large colonial size, prevents them from being grazed when blooms occur in the spring (Kagami 2009).
Similar genera:
Occasionally Tabellaria colonies can take on a cruciate pattern of four cells, instead of the usual zig-zag pattern, and in that form may resemble Asterionella. The more rectangular cell shape is easy to distinguish from the "dog-bone" shape of Asterionella cells.
Chytrid parasite:
During blooms, may become infested with chytrid fungal parasites. A common planktonic species around the world. Introduced by humans into new habitats. Its concentration increases with eutrophication of lakes due to anthropogenic causes (Spaulding 2009).
Habitat:
Perhaps the most ubiquitous diatom during vernal blooms in temperate freshwater lakes. John Lund studied the ecology of Asterionella formosa (and other diatoms) in Lake Windermere, English Lake District, for several decades as referenced in Fogg (1965) and reviewed by Maberly et al. (2003).
References:
Fogg, G.E. 1965. Algal cultures and phytoplankton ecology. Wisconsin Press (269 pp). Guiry, M.D. and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 07 May 2013. Kagami, M., N. R. Helmsing and E. van Donk. (2011). Parasitic chytrids could promote copepod survival by mediating material transfer from inedible diatoms. Hydrobiologia 659(1):49-54. Maberly, S.C., M.A. Hurley, C. Butterwick, J.E. Corry, S.I. Heaney, A.E. Irish, G.H.M. Jaworski, J.W.G. Lund, C.S. Reynolds, and J.V. Roscoe 2006. The rise and fall of Asterionella formosa in the south basin of Windermere: analysis of a 45-year series of data. Freshwater Biology 31:19-34. Spaulding, S., and Edlund, M. (2009). Asterionella. In: Diatoms of the United States.