Caulerpa taxifolia: history of spread and control efforts in NSW
Caulerpa taxifolia was first reported in temperate Australian waters in 2000. It is now established in 9 locations in New South Wales. Prior to its discovery in temperate Australia, this species had been classified as a ‘marine pest’ based on its rapid spread and domination of several subtidal areas in the Mediterranean. In Australia, the situation is complicated because C. taxifolia occurs naturally in tropical waters, extending into the subtropical areas of southern Queensland. Nevertheless, the species is classified as a noxious pest in southern states and programs to attempt its eradication in NSW and South Australia have been initiated.
Possible eradication techniques for C. taxifolia trialed in NSW included smothering with a range of materials, underwater suction devices, handpicking and the application of salt. Results showed that C. taxifolia is readily killed by a layer of salt granules. Applications over large areas can drastically reduce the areal coverage and limit the alga’s spread. Results from such large-scale applications have been patchy, however, with good success in Lake Macquarie but only short-term relief in other estuaries. Targetted applications of salt at high risk sites such as boat ramps is continuing in an effort to prevent fragments being inadvertently transferred to other estuaries.
Regular mapping of C. taxifolia beds in summer and winter over 4 years has allowed an assessment of spatial and temporal variability in abundance of the seaweed and the identification of new areas requiring treatment with salt or other management responses.