Seagrass keeps more than dugongs alive!

“The world’s seagrass meadows act like great carbon sinks sequestering twice the amount of carbon a tropical forest of the same size can store…” What? Really? I didn’t know that!

Feet up, Pinot Gris in hand and watching Nat Geo Wild’s Australia’s Hidden Islands, I was engaging in some armchair sight-seeing of Fraser Island. I heard this statement. I rewound the programme and replayed it! I heard right! On the screen was a dugong cow grazing on the seagrass munching away through 28kg of seagrass a day!

“Just one hectare of seagrass can capture 27.4 tonnes of carbon every year and produce 100,000 litres of oxygen per day, enough for 200 people to breathe.”

I’m suddenly fascinated by seagrass, something I like to kayak over on the river in Sussex Inlet, south coast of NSW. It’s great to see fish and sting rays startle and swish away as I pass. But I’ve not thought much more about it. Some people don’t like it around their jetty and illegally try to remove it. Instinctually, I knew this was wrong. Ruining natural habitats is not something that would occur to me let alone choose to do! But now I know a lot more about why it’s wrong.

If we’re going to continue to BREATHE, we need oxygen in the air and carbon stored in the earth. We need just the right mixture for our world to be healthy.

Mangroves, seagrass meadows and tidal wetlands (blue carbon coastal ecosystems) have unmatched ability to suck CO2 out of the atmosphere and store it in the ground below. This process is called carbon sequestration. Carbon is stored in the soil of blue carbon habitats for thousands of years. When these habitats are damaged or destroyed the carbon can be released as CO2 back into the atmosphere.

(Forests are also good at carbon sequestration, but trees have limited storage: they get saturated and have a shorter storage life, say 100 years. Coal is the result of ancient forest and algae carbon sequestration.)

Seagrass meadows are diminishing in size. The reduction in available light caused by enhanced suspended sediment loads and elevated nutrient concentrations, is the most widespread and pervasive cause of seagrass decline. This is a result of coastal discharges including outfalls of industry, urban stormwater, wastes from aquaculture operations (think fish farms) and sewage discharged from boats and ships. They are also susceptible to fishing and boating pressures.

Seagrass is also important for binding sediment, stabilising shore lines against erosion and providing the nursery habitat for fish, crustaceans and molluscs. Sea turtles and dugongs graze directly on seagrass, an important enough point, and they spread seagrass seeds as they poo!

It seems to me that seagrass is extremely important and should be preserved and promoted as necessary to the health of all creatures on earth.

I hope you stayed with me on this one! Following my curiosity has once again paid dividends: not to the writing of my novel – unfortunately – but to my understanding of the earth and my place in it. I hope that I’ve passed along some knowledge that will affect your life – at least so you can prevent anyone you know from clearing the seagrass around their jetty!

Thanks to Foxtel’s Nat Geo Wild and

https://ozcoasts.org.au/indicators/biophysical-indicators/changes_seagrass_area/

amongst others.