Mediterranean clone of caulerpa
(Caulerpa taxifolia (Vahl) C. Agardth)

Overview

Appearance

Caulerpa taxifolia is an invasive marine alga that is often referred to as "Killer Algae".

Foliage

Fronds are fern-like, bright green, pinnate, and from 2-26 in. (5-65 cm) long that extend upward from horizontal stolons. The stolons can grow to 10 ft. (3 m) long and attach to underwater surfaces such as rocks, mud, or sand via root-like rhizoids.

Flowers

Does not flower.

Fruit

There is no sexual reproduction; propagation is purely vegetative. 0.5 in. (1.2 cm) long stem and stolon fragments can grow into new algae. These fragments are easily transported by boating and fishing activities.

Ecological Threat

The non-invasive form of Caulerpa taxifolia is native to the Caribbean, Indo-Pacific and the Red Sea. A clone of the species was cultured for display at the Stuttgart Aquarium in Germany and provided to aquariums in France and Monaco. It either escaped from or was released from an aquarium into the Mediterranean Sea in 1984 where it spread rapidly, densely blanketing thousands of acres of underwater surfaces. Populations of the invasive Mediterranean aquarium strain were discovered in 2000 in California and threaten native kelp and eelgrass meadows. The invasive clone is genetically distinct from the native (DNA tests are necessary to distinguish them) and it tolerates cooler water, grows more rapidly, and grows at greater depth than the native species. Once established, this alga becomes the dominant species, altering native algal and marine animal communities. Infestations negatively affect tourism, commercial fishing, and recreational activities. The invasive clone was designated in 1999 as a prohibited species under the Federal Noxious Weed Act. Its current distribution includes Croatia, France, Italy, Monaco, Spain (Mediterranean Sea, Adriatic Sea), Australia and the United States.

Resources

• National Marine Fisheries Service -
• U.S. Department of Agriculture National Invasive Species Information Center -
• Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS

Selected Images

Maps

Invasive Listing Sources

• Federal Noxious Weeds
• Indiana Invasive Species Council - Invasive Plant List
• Indiana Pest Species
• Indiana Prohibited Plant Species
• Maryland Aquatic Nuisance Species Plan
• Maryland Code and Regulations Nonative Aquatic Organisms
• Maryland Invasive Species Council - Invasive Species of Concern in Maryland
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• South Carolina Illegal Aquatic Plants
• South Carolina Plant Pest List
• USDA APHIS Regulated Pest List
• WeedUS - Database of Plants Invading Natural Areas in the United States
• Wisconsin's Invasive species rule – NR 40

References