Sharks As Environmentalists?

In 2011, an extreme marine heatwave wiped out 25% of one of the world's largest and most biodiverse seagrass meadows in Shark Bay, Western Australia. Dudongs (marine Mammals) grazed on the seagrass but they left at the time of the heatwave. A heat-resistant seagrass could help recovery in an area of the bay. This provided the conditions for an experiment, evaluating the importance of sharks in the ecosystem's recovery (https://www.theguardian.com/environment/2021/mar/22/sharks-critical-restoring-climate-damaged-ecosystems-study). The shark is an apex predator. Their presence reduces the time the dugongs can graze on the seagrass. The scientists replicated the feeding durations of dugongs with and without sharks. They sent down scuba divers with trowels to carry out marine 'gardening'. The grazing of dugongs in the absence of sharks, would mean the meadow could never recover. Sharks appear to be critical for ecosystem recovery.