Seagrass saviour

By David Kavanagh | posted on April 11, 2019

A PORTION of seagrass in the Oyster Harbour Catchment has been entirely rehabilitated, in what the environmental consultant behind the project describes as the largest scale recovery of its kind in the world.

Geoff Bastyan first conducted major trials at the three kilometre stretch from Swan Point to the harbour’s east in 1997, determining that the section had experienced unsustainable loss.

“The main aim of that was to select areas where there was very little seagrass returning and facilitate that rapid infill in time,” Mr Bastyan said.

“Back in the 90s and even into the 2000s, it was believed that seagrass couldn’t be restored.

“Since then, there has been a combination of both restoration work and natural regrowth and re-colonisation by seed.

“It’s 100 per cent regrown from the very shallows … down to a mean water depth of 2.8 metres.”

Mr Bastyan is currently in the process of rectifying and computing aerial photographs of the site, taken between 1989 and April 2017, that he will use to prepare an educational package for schools, universities and other interest groups in the region.

By counting and comparing the pixels of black and light areas in the photos, it can be accurately determined just how much the seagrass has grown.

“I think it’s an important thing to get that information out there, particularly for the land care groups working in the catchment,” Mr Bastyan said.

“This is something positive and it’ll get them the extra incentive just to keep on doing the good work that’s been done.

“The schools in particular will benefit because it’s the next generation coming through that I think need to be aware and involved in rehabilitation efforts.”

According to Mr Bastyan, seagrass plays a vital role in climate change mitigation and sustaining marine biodiversity.

“The seagrass meadows here, even after a relatively short time span, lock up 30 to 50 times the amount of carbon that the Amazon rainforest does,” he said.

“Seagrass improves the water quality and provides an enormous amount of habitat for fish, particularly juvenile or spawning fish.”

Although Mr Bastyan has garnered financial support from a variety of sources over the decades, the educational packages he expects to have completed within the next four weeks are funded largely by a grant from the Great Southern Development Commission.

Mr Bastyan received a $12,000 grant from the GSDC as the winner of the 2016 GSDC medal.

GSDC Chair Ross Thornton said the biennial award celebrated best practice in the management of natural resources.

“Past medal recipients include people who have shown their peers how to restore damaged ecosystems, how to work with natural resources to be more productive and how to maintain the exceptional natural qualities of our region,” he said.

Mr Bastyan hopes to extend the scope of his project by planting another species of seagrass at deeper points within the harbour.

“There’s plenty of potential for the posidonia sinuosa to grow well down to the five metre contour,” he said.

“That’s a significant proportion of the total seabed in Oyster Harbour.”