Is this the world’s most overlooked ecosystem?
Under the sea exists a lifeform vital to the health of marine ecosystems and beneficial to humans.
Well, seagrass. Which is a flowering plant, more like a lily than a grass.
If you’re feeling surprised, you’re not alone. The old saying “out of sight, out of mind” sadly rings true for the plight of seagrass. Under the water where most people won’t see it, it’s easy for seagrass to be overlooked.
But there are many good reasons for us to all to sit up and pay attention.
Because seagrass isn’t just a champion for critters under the sea.
It could also be protecting your home and lifestyle.
I spoke to Dr Jennifer Verduin from Murdoch University to find out more.
How to save seagrass
Jennifer’s work sees her helping out with seagrass rehabilitation projects.
Basically, when seagrass is removed from an area through dredging or other destructive activities, a team of people will plant it somewhere else.
One of the largest seagrass rehabilitation projects was the replanting of more than 3 hectares of seagrass in Cockburn Sound.
A team of students, researchers and volunteers on scuba swam down to take plants by hand that were about to be dredged.
It took between six and 15 divers per day, each diving 3 or 4 hours per day to move the seagrass sprigs to their new home in Cockburn Sound. They anchored them with large staples, manually moving over 14,000 sprigs in the first year, and they continued to move tens of thousands of sprigs over the next few years.
The seagrass grew and began flowering. It continues to thrive to this day.
There’s plenty of fish in the sea(grass)
So the question on your mind might be why go through all that effort? And I’m glad you asked.
Firstly, seagrass sustains life. Animals hide, feed and breed in it. Even the dead plants can create a meal for crabs.
“One hectare [of seagrass] … is home to about 80,000 fish alone,” Jennifer tells us.
And it’s not just fish. Turtles, sharks, dugongs, octopuses, crabs and a slew of sediment-dwelling infauna are just some of the species to call seagrass home.
If you’re a beach lover, you should also be a seagrass lover.
Because seagrass protects beaches from eroding and ultimately disappearing.
It’s been a stormy winter in Perth. During storms, waves hit the coast hard and drag away sand from the shores. You may have noticed certain Perth beaches have been cut away as a result of recent storms.
And it’s not just the beach bums who’ll be affected by coastal erosion. The Aussie dream is a big beachfront house overlooking the sea. But there’s a very real threat that those homes will eventually fall into the sea.
Don’t believe me? Just look at the situation in Seabird, a seaside town 40 minutes north of Joondalup.
After losing a road to coastal erosion, 15 houses were at risk of being swallowed by the sea. They had to build a seawall, which meant losing their beach to protect their properties.
Groynes—long structures that extend into the water to interrupt water flow—were also proposed as a potential fix, but one that was too costly to explore.
All of these man-made solutions come with a big price tag, and they’re often only temporary or just move the problem further downstream.
For example, a groyne might slow coastal erosion on one side of it but not the other, so you end up having to build multiple groynes in a row along the coast.
Seagrass is like a natural coastal engineer. It does the hard work for us.
“Each individual species can actually retain sand within its meadows to a certain degree,” Jennifer says.
“When the incoming waves come in … they’re actually dampened by the seagrass, so slowing it down, and that’s how sediment can settle out within seagrass meadows.”
It’s like sand dunes. The more vegetation on a dune, the better its resistance to wind blowing away the sand.
There are other ways to protect the coast. Jennifer tells me installing artificial reefs would have a similar effect. But seagrass is still a better, more natural way.
“You could have seagrasses in a larger amount along the coast … and that would help protect the coast and also provide more food for fish, but also for people, and more recreational value for fishing,” Jennifer says.
Save the seagrass, save the world
Carbon is the enemy in the battle against climate change, and seagrass could be our hero.
“They’re actually more efficient than forests in terms of carbon storage,” Jennifer tells us.
“Seagrasses live in less than about 0.2% of the world’s oceans, but they can actually hold up to more than 80,000 tonnes [of carbon] per square kilometre … that’s more than twice that a typical forest can store.”
But if we don’t take notice now, it might be too late.
Jennifer says it has been quoted that we are losing a soccer field size of seagrass every 30 minutes.
Coastal developments, dredging, pollution and rising ocean temperatures all threaten the future of our seagrass.
But with rehabilitation and further research into seagrass distribution and genetics, we may be able to save it. And save a lot of other things in the process.