Caulerpa taxifolia is a green alga with regularly-spaced feather-like fronds growing along a running stolon that is attached to the bottom. The size of the fronds can vary in length and be greater than 60 cm or more. Caulerpa taxifolia is a fast growing marine seaweed that is normally only found in warm tropical waters. It has been widely used as a decorative plant in the marine aquarium trade as it is a very tolerant and easy to keep aquarium species. The ‘aquarium strains' can invade cool temperate waters, and Caulerpa taxifolia has become established in several countries and areas where it is not naturally found.
It is native to tropical regions throughout the world, including tropical and subtropical parts of Australia, with its southern limit at Moreton Bay in Queensland. The invasive 'aquarium strain' was first found near Monaco in the Mediterranean Sea in 1984. It has since colonised thousands of hectares in the Mediterranean from France to Croatia and is now established in California. The invasive strain found in the Mediterranean can tolerate temperatures as low as 5oC and can survive out of water for up to 10 days. It can colonise most kinds of substrates including rock, sand, mud and seagrass beds. It has been found in depths ranging from less than 1 m to over 100 m and is capable of rapid growth. Reproduction of the invasive strain is asexual and dispersal occurs through fragmentation. It has been demonstrated in laboratory experiments that a fragment as small as 1 mm can settle and start growing. Growth rates are greatest in the summer months and lowest during winter.
In Australia, Caulerpa taxifolia has recently been found in eight NSW estuaries. This has raised significant concerns as it is a noxious species with the potential to grow rapidly and smother native seagrass. It may degrade marine ecosystems and threaten biodiversity. It is usually extremely difficult to eliminate aquatic weeds once they have become established in the wild. The NSW Government is applying techniques to eradicate and control the spread of Caulerpa taxifolia in NSW waters.
