Operation Crayweed — Restoring Sydney's Lost Underwater Kelp Forests

Crayweed (Phyllospora comosa), a golden seaweed that once formed dense underwater forests along Sydney's coastline, vanished from the city's reefs in the 1980s — likely due to poor water quality — and did not recover naturally even after water quality improved. Since 2012, Operation Crayweed, led by UNSW Sydney's Centre for Marine Science and Innovation, has restored it by fixing fertile adult plants from healthy populations onto barren reefs with biodegradable mats; the transplant stress triggers spawning, and offspring attach permanently to the reef.
Transplanting has now taken place at nine locations spanning roughly 70 km of coastline, including Cabbage Tree Bay, Freshwater, Kurnell, Long Bay, Little Bay, North and South Bondi, Coogee and Newport. Peer-reviewed monitoring found transplanted crayweed achieves survival and reproduction rates comparable to natural populations, restoring habitat that supports abalone, rock lobsters and other reef species.
The programme is funded by the NSW Department of Primary Industries' Environmental Trust and Recreational Fishing Trust grants, the Australian Research Council, the Sim-Lutton and Breen Initiatives, the John T Reid Foundation and UNSW's Evolution & Ecology Research Centre — a durable, peer-reviewed, multi-funder model now over a decade old.

Read the full analysis: https://www.unsw.edu.au/research/cmsi/research-projects/Marine-Environmental-Sustainability/operation-crayweed-restoring-sydneys-underwater-forests