Their importance comes from their label as "ecosystem engineers"- They create their own habitat. They are large primary producers, they filter water and nutrients heading out to sea, their roots provide stabilisation of the sea-bed and they provide shelter to a diverse range of marine life.
Sea Grasses are affected by natural occurrences, such as storms, and over grazing by marine life, but, in recent years, over 30,000 km2 have been lost to human activities; overfishing, and excessive entry of nutrients (from farming etc) are the main culprits.
Researchers in Western Australia have some good news though, they have successfully "transplanted" seagrass into the Cockburn Sound (near Rockingham, WA). Locally there are large seagrass meadows, but due to industrial action 77% of seagrass meadows have disappeared since 1977, and since the 1980's trials to re-plant seagrass in the area have been unsuccessful, until now.
A collaboration by researchers from UWA’s Oceans Institute, Murdoch University, the Kings Park’s Botanic Garden and Parks Authority held a trial between 2004 and 2008 that has been deemed a success. They planted 50cm shoots into a patch of bare sand at the Northern end of the sound, and picked the patch based on sediment quality, and the plants based on genetic quality as well as water conditions. Previous studies and concentrated only on water quality. At the end of the trial the meadow had become self-sustaining, resulting in a high diversity of marine life, and, in 2010 the plants flowered for the first time and now the meadow resembles any other naturally occurring seagrass meadow in the Cockburn Sound.
This is a great success for reversing some of the damage human industrial action has wrecked on the marine life of the planet, but there is still a long way to go.
For more information on the study, seagrasses and seagrass monitoring, head to the links below.
Image; Brian Skerry (Sea Turtle grazing on seagrass)