Please select your home edition
Pantaenius EU 728x90

Seagrass an unexpected protector of marine history

by Ben Jones 4 Nov 2018 23:31 UTC
Seagrass © Julia Turner

Seagrass meadows are safeguarding shipwrecks off of the Australian coast, with Edith Cowan University (ECU) researchers likening them to security vaults for priceless cultural artefacts.

"Seagrass meadows established in our shores up to 6,000 years ago accumulating several meter-thick sediments underneath their canopies, and recent disturbances and losses have exposed shipwrecks and archaeological artefacts that were embedded and preserved within seagrass sediments," said Dr Oscar Serrano from ECU's School of Science.

"Seagrass meadows trap sediment and particles within their canopy gradually building up the seafloor over decades and centuries by depositing those materials as they grow."

"But once the protective cover of seagrass is gone, the ships begin to break down, which shows if you lose seagrass, you lose important cultural heritage."

The organic and chemical structure of seagrass sedimentary deposits is key to its ability to protect shipwrecks.

The seagrass structure is very resistant to decay, which leads to thick sedimentary deposits that seal oxygen from the sites, preventing decomposition of timbers and other materials.

"This is why we suggest seagrass meadows can be regarded as security vaults for underwater cultural heritage and time capsules of the human past," Dr Serrano said.

European and Australian ships discovered

While Europe is moving to protect ships exposed by loss of seagrass, two known shipwrecks off the Australian coast have received attention.

It's believed around 7,000 shipwrecks exist in Australian coastal waters, including around 1,650 in waters off WA.

Seagrass disturbance led to the unearthing of the James Matthews in 1973, sunk in Cockburn Sound (Western Australia), and the Sydney Cove, which ran aground off Preservation Island (Tasmania).

Artefacts and pieces of the James Matthews' hull have been recovered and conserved, while recovery of beer bottles from the Sydney Cove has led, remarkably, to 220-year-old brewing yeast being cultivated and used to create James Squire's The Wreck porter.

The research team also believe there's significant potential for the archaeological heritage of early Indigenous Australians buried and preserved in seagrass meadows.

However, seagrass meadows are increasingly coming under severe environmental stress due to climate change, weather events and human activity; and unless these effects can be stemmed, the frequency of exposures is likely to increase.

This has already placed European archaeologists and marine scientists in a race against the clock, as seagrass meadow losses in the Mediterranean have exposed Phoenician, Greek and Roman ships and cargo, many of which are thousands of years old.

Conserve or risk treasure hunters

Dr Serrano says his research team, which includes scientists and archaeologists from Denmark, Saudi Arabia, Greece and Australia, is looking to match shipwreck data with seagrass meadow maps.

They believe new acoustic techniques for sub-bottom imaging can allow exploration of underwater sites without disturbing the overlying seagrass meadows.

Where necessary, controlled archaeological excavation could then be undertaken to excavate, document and preserve sites and artefacts according to Dr Dorte Krause-Jensen from Aarhus University in Denmark.

"The danger of not putting programs into place is evidenced by treasure hunters off the Florida coast, who have adopted a destructive technique called 'mailboxing' to search for gold in Spanish galleons," Dr Krause-Jensen said.

"This involves punching holes into sediment to locate and then pillage wrecks, an action that damages seagrass meadows and archaeological remnants."

'Seagrass sedimentary deposits as security vaults and time capsules of the human past' by Dorte Krause-Jensen, Oscar Serrano, Eugenia Apostolaki, David Gregory and Carlos Duarte is published in Ambio.

Related Articles

Upper-ocean warming changing global wave climate
The energy in ocean waves has been increasing Sea level rise puts coastal areas at the forefront of the impacts of climate change, but new research shows they face other climate-related threats as well. Posted today at 10:56 am
S/V Nereida sails around the world - Day 104
We end up drifting in no wind - again.... Monday 10:20pm Sat in the cockpit for a time, after adjusting sails and Fred - a beautiful evening. A bright half moon sending a path of light across the sea to Nereida - refreshing, cool night air - not feeling cold at all... A few clouds... Posted on 16 Jan
S/V Nereida sails around the world - Day 103
Beautiful, relaxed day of good sailing in bright sunshine Sunday Excellent speed continuing to be made - frequently seeing SOG just over 8kt and mostly in the 7-8kt range - making really good progress NE! Posted on 15 Jan
S/V Nereida sails around the world - Day 102
Another colourful sunset tonight - very similar colouring and nearby clouds to yesterday's Saturday 7pm Another colourful sunset tonight - very similar colouring and nearby clouds to yesterday's. Sat out in the cockpit to relax and enjoy the scene - wind still light but we were sailing gently and smoothly at 3-4kt Posted on 14 Jan
Stockton University researches shipwreck
Sitting right beneath a South Jersey bridge Stockton University faculty and students are on the cusp of a unique discovery that sits right beneath a South Jersey bridge. Posted on 13 Jan
S/V Nereida sails around the world - Day 100
One hundred days at sea.... Another problem fixed... Thursday 7:30pm A lovely sunset - and a magnificent Wandering albatross glided by, circled around and came back to have another look! Posted on 12 Jan
S/V Nereida sails around the world - Day 99
Full canvas - and then the wind pipes up...! Wednesday 11pm Underway - wind has backed into the N at 20kt so we can make a course upwind to ENE. Dark, rainy, bashing into the seas - uncomfortable, as always! Posted on 11 Jan
Antarctica Weddell Sea expedition sets sail
Antarctica Weddell Sea expedition sets sail A team of scientists investigating one of the most remote regions in the Antarctica hiding the "historic" Endurance wreckage have embarked on their expedition. Posted on 11 Jan
Bananas preserving Fruit & Veg on Atlantic Voyage
Bananas preserving Fruit & Veg on Atlantic Voyage As part of a green business project, a crew from a Southampton sailing school have had success with a fruit and veg preserving experiment while crossing the Atlantic. Posted on 5 Jan
S/V Nereida sails around the world - Day 72
Jeanne Socrates is attempting to complete a non-stop, solo and unassisted circumnavigation Jeanne Socrates is 76 years of age and is attempting to complete a non-stop, solo and unassisted circumnavigation as the oldest sailor. She left Victoria, British Columbia on October 3, 2018. Posted on 15 Dec 2018
Zhik 2018 Kollition 728x90 BOTTOMMarine Resources BOTTOM