- By Michael Abbott
2007 URG Research - Sydney Metro 38396
NSW Department of Primary Industries - NSW Government
Caulerpa taxifolia is a fast-growing seaweed, nick-named Killer Algae after escaping from aquariums in Germany, where it had been specially bred to be extremely hardy.
Normally only found in warm tropical waters, the aquarium strain has colonised thousands of hectares in the Mediterranean, from France to Croatia, and is now established in California, where it threatens marine biodiversity like any vigorous weed plant.
A group of Sydney dive enthusiasts were concerned the weed would invade North Harbour Aquatic Reserve in Sydney Harbour, after colonies were discovered in NSW estuaries, most likely from plants escaping from anchor chains of visiting ships or from fishing gear .
The reserve protects sealife such as anemones, worms, sponges, shrimps, crabs and molluscs, and shelters seagrass, seahorses and sea dragons, which would all be threatened by the Killer Algae.
An Australian Government grant of more than $11,000 assisted the Underwater Research Group to confirm whether or not Caulerpa taxifolia was present in the North Harbour Aquatic Reserve.
This grant was also used to establish a base-line study of the biodiversity within the North Harbour Aquatic reserve. The data the URG recorded can be used in the future to assess the overall state of this waterway.
Project spokesman Colin Piper, vice-president of the Underwater Research Group, said the group carried out many dives to look for the Killer Algae and found it was present, , but at this stage it appears not to be the Mediterranean strain.
“It is most likely a strain found naturally in Moreton Bay.;
“For the base-line study, we searched along 50 metre transects from a pre-determined GPS position to gather baseline data for the biodiversity survey, and for the Caulerpa research, we used radial searches from a central GPS position.. We have re-visited several of these positions and have noted varying changes in the amount of Caulerpa present.
“We determined that our methodologies worked well and have supplied the data we obtained to the Port Stephens office of NSW Fisheries.” They have visited several of out sites to confirm our findings.
“It has been a highly successful project,” Colin said. “Up to that point divers had reported seeing the Killer Algae, but it was only hearsay,” he said.
“Now we have proved that it is established, and our advice is it is probably not a threat to the same extent it is overseas; Fisheries undertook some eradication programmes but I understand it had a limited degree of effectiveness. Like the cane toad, it has probably migrated south from Moreton Bay.
“But the data we have obtained will allow us to keep a watch on it.”
Further reading here on DPI's website