Karlodinium veneficum

Algal Identification


Harmful Algal Blooms

Harmful Algal Blooms in Maryland

Karlodinium veneficum

Originally isolated in the U.K. as a food source for bivalves, this is a small (9-18 um x 7-14 um) chlorophyll-containing dinoflagellate common to the bay and its tributaries producing known ichthyotoxins as the karlotoxins.  Known as the 'fish-killer,' the toxins now number 5 varieties and are toxic or allelopathic to most taxa containing cholesterol (i.e., phytoplankton, protozoa, and metazoans).  The taxon is generally a spring-to-fall species and contains both toxic and non-toxic strains.  It is autotrophic and mixotrophic with faster growth rates when feeding on prey, often cryptophytes.  It is detectable using remote sensing.

Like all types of phytoplankton,  dinoflagellate species can generate population explosions when habitat conditions (i.e., light, temperature, nutrients, turbulence, predator levels, etc.) are ideal. High density blooms of dinoflagellates such as the potentially toxic Karlodinium micrum may cause water to become discolored a reddish-brown and form Mahogany tides. Mahogany tides may also severely reduce the amount of oxygen available to living resources at localized bloom sites.

Distribution of Karlodinium blooms in MD (2000-2013)

Distribution of Karlodinium blooms in MD (2000-2013)




Annual occurence of Karlodinium blooms in MD (2000-2015)Annual occurence of Karlodinium blooms in MD (2000-2015)



Monthly occurence of Karlodinium in MD (2000-2015)Monthly occurence of Karlodinium in MD (2000-2015)