Golden alga (Prymnesium parvum)

Golden alga Description: First introduced to North America in 1985 with an unknown origin. Extremely toxic .

Habit: Microscopic (about 10 micrometer), flagellated alga with 4 morphologically distinct forms. Two forms are bi-flagellated haploid cell types. One form is a bi-flagellated diploid cell type. Another is a non-motile with no flagella (resting stage). Flagellated forms have a haptonema, specialized external needle-like structures that enables attachment to surfaces. They have 2 saddle shaped chloroplasts that are yellow-green to olive in color. Flagella range from 12-15 micrometers and haptonema ranges from 3-5 micrometers.

Habitat: Found worldwide and often associated with estuarine or marine waters as well as brackish ponds.


Impact and Damage: Capable of forming harmful blooms inland and in coastal aquatic environments and is responsible for devastating fish kills.

Similar species: Prymnesium annuliferum, Prymnesium calathiferum, Prymnesium faveolatum, Prymnesium lepailleurii, Prymnesium nemametecum, Prymnesium parvum and Prymnesium zebrinum.

Monitoring and rapid response: Landscape-scale reductions in nutrient load and hydrologic changes would be required for management of P. parvum blooms. Reduction of ammonium sulfate and other agricultural fertilizers is necessary.

Credits: The information provided in this factsheet was gathered from CABI: Invasive Species Compendium.

Individual species images that appear with a number in a black box are courtesy of the network ( Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (

Common Name:

Golden alga

Scientific Name:

Prymnesium parvum


(Brown algae)





USDA Symbol: