Ridgley family work to rebuild Shark Bay marine ecosystem after 2011 heatwave killed seagrass meadows

A family owned charter operator is on a mission restore the world’s largest seagrass meadow in Shark Bay, after a marine heatwave had devastating impacts on the ecosystem. The Shark Bay World Heritage site is home to 12 of the world’s 60 seagrass species and holds the largest seagrass meadow in the world, with more than 4000sqkm of seagrass stretching along the coast. A 2011 marine heatwave resulted in a catastrophic loss of seagrass, with surveys since showing populations continue to decline. In a bid to restore the meadow, local family tour company Perfect Nature Cruises, in partnership with OzFish, is undertaking seagrass restoration, having released this week their 2000th sand sack for 2024. It is up from the 1600 sacks released and monitored last year. Seagrass restorer Liam Ridgley said last year’s bags, each containing 15 seagrass seedlings, were found to stabilise the sand bank and allow additional species to grow as a result. The seagrass meadow in Shark Bay is an important feeding ground for dugongs and other marine animals. Mr Ridgley said his father Greg, who has operated the charter for 26 years, has watched populations diminish over those years. “He tells stories of coming out to the seagrass bank and seeing 100 dugongs in a day. Now, if you told someone you saw 100 dugongs in a day, that would be a very, very far-fetched story,” he said. Mr Ridgley said being involved in seagrass restoration was not for financial gain, but rather to preserve the culturally and ecologically sensitive coastline of their home town. Seagrass beds store up to 83,000 metric tonnes of carbon per square kilometre, compared to a forest storing about 30,000 metric tonnes per square kilometre. “Shark Bay seagrass meadow is the world’s largest marine carbon sink. The carbon release in the atmosphere is unmeasurable,” Mr Ridgley said. “The loss of seagrass has affected a lot of marine life, a lot of ecosystems, and there’s a lot of seagrass washing up on the beach as a direct result of erosion. So we’re trying to slow that all down as well.” The Ridgley family has an ambitious goal to expand the operation in 2025 and release 10,000 bags, which would cover about 10ha. “We’ve got a lot of support from the shire (of Shark Bay) and the Malgana people to continue the project,” he said.