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Name derivation:

Named after Karen Steidinger in recognition of her many contributions to dinoflagellate research.



Karenia G.Hansen & Moestrup 2000; currently there are 12 species accepted taxonomically (Guiry and Guiry 2018).

Class Dinophyceae; Order Gymnodiniales

Type species:  Karenia brevis

Basionym:  Gymnodinium breve Davis

Separated from Gymnodinium on the basis of large subunit (LSU) rDNA (Daugbjerg et al. 2000).

Synonym:  Ptychodiscus brevis (Davis) Steidinger.


Dinoflagellates unarmored (no heavy cellulose wall plates), contain chloroplasts with fucoxanthin the principal carotenoid accessory pigment.  The apical groove extending from apical to dorsal side is straight. 

Similar genera:




Ichtyotoxic:  K. brevis produces brevetoxins (Daugbjerg et al. 2000).

The action of brevetoxins is persistent activation of sodium channels and thus repetitive firing of nerves.  The effects are irreversible and lead to massive fish kills.  Humans can inhale aerosolized toxins, or ingest toxins by eating marine invertebrates.  Brevetoxins are bioaccumulated, thus can be present even in the absence of dinoflagellate blooms (Flewelling et al. 2012).



Marine plankton.


Daugbjerg, N., G. Hansen, J. Larsen and O. Moestrup  2000.  Phylogeny of some of the major genera of dinoflagellates based on ultrastructure and partial LSU rDNA sequence data, including the erectiohn of three new genera of unarmoured dinoflagellates.  Phycologia 39(4):302-317.

Guiry, M.D. and G.M. Guiry  2018.  AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.  http://www.algaebase.org; searched on 08 February 2013.

Flewelling, L.J., J.H. Landsberg & J.P. Naar  2012.  Karenia brevis red tides and brevetoxin-contaminated fish:  a high-risk factor for Florida’s scavenging shorebirds?  Journal of the Botanica Marina 55(1):31-37.