How seagrass helps tackle climate change | Dolphins: Is Our Love Too Deep? | ABC TV + iview

Seagrasses are the unsung heroes of the ocean. Often referred to as the ocean's lungs, they remove carbon dioxide and release life-sustaining oxygen when photosynthesizing. Seagrasses are also responsible for storing 5% of the world's carbon, some serving as a crucial carbon sink, and they sequester carbon at a mind-boggling rate of 35 times faster than tropical rainforests. In Western Australia, Shark Bay is home to some of the largest seagrass meadows on the planet, which cover more than 4,000 square kilometres of seafloor. Shark Bay is also home to the largest seagrass clone on Earth, which stretches for more than 180 kilometres, making it the largest known plant in the world. Shark Bay is a meeting place for the desert, cool, temperate and warm tropical waters, and boasts a stunning array of plant and animal life. But perhaps the most breathtaking feature of this magical place is the seagrass. With 12 species found here, the seagrass meadows are some of the most diverse on the planet. These grasses are a vital source of food and shelter for Shark Bay's thriving marine ecosystem, but all this is under threat. In 2011, a devastating marine heat wave, a period of abnormally high temperatures, hit Shark Bay. Sea surface temperatures rose by a staggering four degrees and resulted in widespread damage and loss of the seagrass meadows. Over 1,000 square kilometres of seagrass was lost completely or destroyed. An unprecedented event, this loss was the largest in recorded history. Being a shallow water ecosystem, Shark Bay is particularly vulnerable to the impacts of a marine heat wave. Shallow waters can heat up more quickly than deeper waters, leading to larger increases in temperatures and more stress placed on the seagrass. This had a devastating knock-on effect on the other marine life in Shark Bay. Not only did it cause a decline in the bay's iconic dolphin population, but the ripple effects were felt throughout the entire ecosystem. Seagrass provides habitat and food for fish, crustaceans and other animals at the bottom of the food web. So when seagrass is lost, these animals are lost and the effects cascade right up through the food chain to larger animals. Green turtles and dugongs, which rely on seagrass as their primary food source, were severely affected. Cormorant breeding was impacted as fish numbers dropped. On top of this, an estimated nine million tonnes of carbon was released into the atmosphere. But there is hope. The University of Western Australia has teamed up with Indigenous Malgana Rangers and Malgana divers from Tidal Moon Australia to embark on a groundbreaking restoration project. The divers carefully collect different species of seagrass from areas close to the restoration project sites. The UWA team then methodically replant the collected seagrasses, painstakingly transplanting thousands of seagrass cuttings over 10,000 square metres within the restoration site. To date, over 85 per cent has survived. UWA is also deploying seagrass snaggers at the site. The snaggers are biodegradable hessian sacks filled with sand and are placed in patterns on the sea floor so that the seagrass clings to them and creates new seagrass habitats for marine animals. Although the project is expected to take decades, the results so far are promising. With this ambitious plan in motion, the team have provided a positive step in helping to restore this incredible seagrass ecosystem, which is the foundation of the astounding marine life of the Shark Bay World Heritage Area.