Wednesday, April 13, 2016

Fruits and flowers under the sea

Surely plants with fruits and flowers live only on the land! Not so. A variety of true plants live in the coastal waters girting the Australian continent. Not that you may have noticed them.

Hang on, you might have noticed in a 'white noise' kind of a way. Have you ever turned up to a shore worthy of a boat launch and seen piles of strappy sea wrack mounds on the beach? Or have you noticed, when you see a beautiful the clear blue coastal water the darker shadowy patches breaking up your view of the sandy bottom? These darker blue-green patches are not the colourful coral reefs or the beautiful sponge gardens featured in many documentaries or tourism promotions. You are looking at the modest yet amazing seagrass meadows of Australia.
"Moreton Bay Seagrasses" brochure by UTC

Australia is the home to 30 of the 57 species worldwide. They are not grasses but terrestrial plants from the same line as lillies who have returned to live in the sea the same way that marine mammals did. Unlike the macro or micro algaes (seaweeds) they have flowers and fruits and roots too. The health of our coastal waters and the changing atmosphere are tied to these dynamic meadows.

Seagrasses have been a resource on the land as well as off. Historically we know that seagrass wrack was commonly used as insulation and sound proofing in early dwellings and it is non-flammable due to high silicon content. It has been used as thatching for roofs, binding soil, stuffing and packaging as well as weaving, fibre products and paper making.

Seagrasses of South Australia brochure, Environment Protection Agency, SA

And we know that fish and other animals use the seagrass as nurseries and hunting areas in the end ensuring food for fish, dugong, turtles, swans and us too! 

Most importantly these marine plants have a key part to play in mitigating rising CO2 in the climate change puzzle. 

The CSIRO Coastal Carbon Cluster website tells us that "Wetland vegetation (seagrass, mangroves, saltmarsh) occupy only two per cent of the world's seabed area, but are responsible for 50 per cent of the carbon transfer to the ocean sediments."

Seagrass meadows have proven to be strong carbon (Blue Carbon) sinks "with a hectare of the most effective seagrass meadows exeeding by tenfold the CO2 sink capacity of the pristine Amazonian forest" (taken from "Seagrass and the carbon paradox" by Carlos Duarte here)

Go seagrasses! 

Students wishing to take up a seagrass art/craft activity can visit the AUSMEPA Kids Investigating Sea Solutions (KISS) at

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