Golden kelp (Ecklonia radiata), forms the backbone of the Great Southern Reef and is distributed throughout the entire 8,000km range of this interconnected temperate reef system. However, in Victoria's Port Phillip Bay, the ecosystem has been under siege. Sea urchins, flourishing due to an imbalance in the food chain, have overgrazed 60 percent of the reefs, decimating the once widespread kelp and seaweed habitat.
This ecological crisis can be traced back to the 1980s when excess nutrients from wastewater treatment plants led to a surge in weedy seaweed, a primary food source for purple sea urchins. During the millennium drought, fewer nutrients entered the bay and seaweed growth reduced, so the urchins began eating kelp and seaweed growing on the reefs.
Addressing this complex issue requires innovative solutions, and a collaborative effort is underway to restore the golden kelp forest habitats in Port Phillip Bay. Deakin University, in partnership with The Nature Conservancy, The University of Melbourne, and Parks Victoria, is piloting innovative techniques to cultivate and restore golden kelp.
Based at the Deakin Centre for Marine Science, Dr. Paul Carnell and Dr. Prue Francis are leading the kelp cultivation component of the project, marking the first trial of its kind on this species in Victoria. The researchers are cultivating golden kelp at a microscopic level, growing over 6 million juvenile spores onto twine or embedded in gravel pellets. These trials aim to research and develop the most effective methods for golden kelp cultivation and restoration in the bay, setting the stage for future large-scale efforts.
"The results of the one hectare-sized planting will guide future restoration efforts," says Dr. Prue Francis, emphasising the project's potential to inform best practices for kelp restoration.
The project also includes trials optimising growth in lab aquaria, ensuring that the young kelp, or "kelplings," have the best chance of survival when transplanted to sites in Northern Port Phillip Bay. At these sites, researchers will conduct trials on restoration methods and manage urchin populations to reduce overgrazing pressure on the kelp habitats.