Description:
In 2007 a patch of Caulerpa taxifolia (invasive marine seaweed) was discovered in Wallagoot Lake about 500 metres from Bournda Environmental Education Centre (EEC).
C. taxifolia is a bright green invasive seaweed that has been found in thirteen estuaries in NSW including seven South Coast estuaries. Once Caulerpa is in an estuary it is virtually impossible to eradicate.
C. taxifolia has rapid growth and may out-compete and smother native flora such as seagrass which is ecological important as recruitment, nursery and refuge sites for many species of native fish and invertebrates. All species of Caulerpa (including those native to NSW) produce toxic substances (caulerpenynes). These act as deterrents against many epiphytes and herbivores (eg. sea slugs, abalone and sea urchins), thus limiting grazing which might otherwise reduce the biomass of the weed.
As far as we know the incidence of C. taxifolia in Wallagoot is restricted to a small patch, located near Scotts Bay. The site is surrounded by a netting exclusion zone marked by 4 yellow buoys. The shallow waters at Wallagoot are ideal for salting, one of the few known effective treatments. Salting work was carried out by the NSW Department of Primary Industry (DPI), Aquatic Biosecurity Unit in October 2007.
The salting in 2007 largely destroyed C. taxifolia but unfortunately a recent survey of the site conducted by Bournda EEC staff showed that it is still present. Bournda staff have mapped the location of some of those plants using GPS and have plotted this data in our Geographic Information System (GIS)
Map from GIS showing information on Caulerpa distribution in January 2008
Map from GIS showing Caulerpa distribution in March 2008
There is an urgent need to conduct further surveys to establish whether other patches of C. taxifolia are present in Wallagoot. Obviously other waterways could also be at risk of contamination so locals need to be aware of it and be vigilant in reporting any occurrences to DPI Aquatic Biosecurity Unit on 02 4916 3877 or aquatic.pests@dpi.nsw.gov.au
Your students could be part of an ongoing project to eliminate C. taxifolia from Wallagoot
NRM Focus (CAP Focus area):
• Coast & Marine (Coasts & Estuary Management, Biodiversity, Research)
Site Investigation Options: Students can assist locate Caulerpa infestations
Target Audience: Stage 4 - 6 students, Science and Geography
Host organisation(s): Bournda EEC
Contact Information: Doug Reckord
Email: douglas.reckord@det.nsw.edu.au