Prymnesium parvum Blooms in Florida (2005-present)

Prymnesium parvum, also known as golden algae, is a naturally occurring microscopic member of the phytoplankton community. This algal species is found in brackish waters worldwide and has been noted in Florida waters since 2005 (See Figure 1).

It is a known toxin producer and has caused large-scale fish kills in other parts of the United States and the world. It can cause ecological and economic harm particularly to aquaculture industries. In Florida, fish kills caused by P. parvum have been localized to small ponds in residential areas and golf courses and the Intracoastal Waterway (See Figure 2).

Prymnesium parvum is found throughout the water column, and the formation of a resting stage in the sediment, called a cyst, has been hypothesized. In Florida, P. parvum can be found year round. However, fish kills have been recorded only in winter months when water temperatures are below 30°C (86°F), and salinity is between 1 and 5 parts per thousand. Research has shown that P. parvum can produce allelopathic compounds--chemicals that inhibit growth in another species of plant--that give the cells a competitive advantage over other phytoplankton and grazers. P. parvum also produces an ichthyotoxin, or fish toxin, called prymnesin, which affects gill-breathing organisms by rupturing gill membranes. To date, no adverse health impacts have been noted for humans or non-gill-breathing wildlife that have come in contact with waters experiencing a P. parvum bloom.

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