Caulerpa (Caulerpa taxifolia)
Family:
Status:
Description:
Caulerpa is a seaweed which grows in saltwater on the floor of coastal lakes, estuaries and harbours. It grows from creeping stolons, which are long branching "runners", attached to the floor of the lake by root -like rhizoids. Leaves are fern or feather-like and can be from 5-65cm long.
Preferred habitat and impacts:
Caulerpa has a wide range of environmental tolerances. It can grow at various depths.
It is likely to overwhelm local native seagrasses, which provide food and shelter for fish and their young, and numerous other aquatic animals. Caulerpa is not palatable to fish, and they tend to avoid areas where it grows. It therefore has the potential to greatly damage fisheries.
Its natural distribution is the tropical areas of the Indian, Atlantic and Pacific Oceans, but it has invaded many other sites around the world. It has proven itself capable of growing in non-tropical waters. For example it has been found in some South Australian sites, as well as in several sites in Queensland and New South Wales, one of which is Lake Conjola north of Ulladulla.
Dispersal:
Initial introduction in Australia may have been from discarded material from saltwater aquaria, as the plant has been sold as an aquarium ornamental plant.
Dispersal is from broken off pieces of the stolon. It can grow from fragments as small as 2mm long. The plant is likely to be broken up by disturbance from such things as fishing lines, anchors and outboard motors. Fragments can drift around in the water, to settle and form new colonies, or they may attach to anything that has been in infested water such as boats, fishing tackle, ropes and chains, wetsuits or boots. They may even attach to swimming people or animals. Pieces can survive out of the water for up to ten days, so there is great potential for them to be moved from one water body to another on boats or equipment, or even by dogs swimming in the water.
Look-alikes:
None of the native seagrasses in the region are similar to caulerpa. Most native seagrasses have long narrow strap-like leaves, varying from a few mm to about 1cm wide. One, Halophila has small paddle-shaped oval leaves. None have feathery leaves. Some freshwater plants have feathery looking foliage, but caulerpa does not grow in freshwater.
Control
Report any suspected occurrences of caulerpa anywhere other than Lake Conjola immediately to NSW Fisheries, with an accurate map of the location, the depth of the infestation and the substrate (sand, rocky reef, mud). Take a specimen of the plant and press it between several thicknesses of newspaper under a heavy object such as a large book, so that your identification can be confirmed.
Avoid boating, fishing, swimming or swimming your dog in infested areas. Check your boat and equipment after using it in any coastal lakes or estuaries. If you find pieces of caulerpa, press a specimen, seal the rest of the material in a plastic bag and dispose of it where it cannot get into waterways, and notify NSW Fisheries.
For more information and a photo of caulerpa, check these websites:
www.fisheries.nsw.gov.au/conservation/pests/caulerpa.htm
www.pir.sa.gov.au/dhtml/ss/section.php?sectID=1373&tempID=3