From The University of Sydney (AU)
5.21.24
Port Hacking oyster reef. March 2020. Credit: Oskar Johansson
No ‘one size fits all’ when it comes to rebuilding reefs
Researchers at the University of Sydney have revealed how our oyster reefs can provide lessons on reef restoration projects.
More than 85 percent of naturally occurring oyster reefs have been lost in recent decades due to disease, overharvesting, global warming and pollution. Three reefs that have maintained their oyster populations naturally are in New South Wales, Australia: Gamay (Botany Bay), Port Hacking and Crookhaven (on the Shoalhaven).
Scientists from the University of Sydney and the Sydney Institute of Marine Science (SIMS) have studied these oyster havens to find out what has sustained their populations and how lessons from the reefs can be applied to reef restoration projects.
They found reef restoration must consider local wave and tidal impacts, reef shape and orientation. Each site can then maximize oyster sustainability, provide habitats for grasses, and act as coastal protection from storms and erosion.
The study has been published in Geomorphology.
Author Professor Ana Vila-Concejo from the School of Geosciences at the University of Sydney said there is no one size fits all when it comes to oyster restoration.
“It is vital that reef restoration considers local factors. Different locations need different sized reefs and varied design. This can also help mitigate the erosion processes caused by urbanisation,” she said.
“As well as helping to satisfy the demand for oysters as food, these reefs are an important barrier that can protect coastlines from erosion and storm damage.”
Reef restoration
With the global market for oysters estimated at more than $US8 billion a year, reef restoration is booming. New York City alone is spending millions of dollars on an oyster restoration project to regrow a billion oysters by 2035.
In Australia, the federal government has funded the country’s largest restoration project, Reef Builder, to recover shellfish reefs throughout the country. Many restoration projects are under way in Noosa (Queensland), Gamay (Sydney), Port Phillip Bay (Victoria), Glenelg (South Australia), Albany (Western Australia) and the Swan-Canning estuary in Perth (Western Australia), making the timing of the study highly relevant.
Geoscientists refer to the ‘ecomorphodynamics’ of a site to understand how the geophysical structure of a reef, combined with impacts from ocean and tides, affect the ecology of the overall structure.
Lead author of the study Francesca Roncolato, a graduate of the Master of Marine Science and Management program, said: “The totality of these dynamics has important implications for oyster reef restoration. By understanding the natural success of the three reefs we studied, we can apply that knowledge to the placement and design of restored reefs.
“As geomorphologists we know not all coasts need protection. In some places, coastal protection can be detrimental,” she said.
“For instance, putting artificial barriers in front of a small sandy estuarine beach could inadvertently reduce the wave and tidal energy levels required to maintain the beach. This could turn a lovely sandy waterfront into a mudflat.”
Three types of oyster reef
Study areas in (A) SE Australia showing (B) Gamay (Botany Bay), (C) Port Hacking and (D) Crookhaven, along with their topo-bathymetry. The oyster reefs within each site (outlined in gray) are shown in (E, F and G) with hydrodynamic instrument placements indicated using colored stars, with red = exposed estuary, green = exposed reef (ocean side), blue = exposed reef (bay side) and purple = protected estuary Imagery sourced from DPE (2014) and digital elevation model from DPE (2019). Credit: Geomorphology (2024).
Professor Vila-Concejo said that the three reefs studied displayed distinct shapes: patch reefs, string reefs and fringing reefs.
“Oyster reefs display a continuum of shape and orientation. But we can see three general morphologies,” she said.
Patch reefs, like the one at Crookhaven, are generally aligned at right angles to the tidal currents and incoming waves. String reefs, like the one at Gamay, are more like broken-up barriers, obliquely aligned to tidal flows. And then there are fringing reefs, like the one at Port Hacking, which act as barriers with the lowest energy impact from tide and ocean waves.
Professor Vila-Concejo said: “Our findings are important to inform future reef restoration under increasingly severe climate change conditions to optimise the ecosystems of restored oyster reefs; it is clear that we need more geomorphology input to include ecomorphodynamics in restoration design.”
See the full article here.
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The University of Sydney (AU)
Our founding principle as Australia’s first university, U Sydney was that we would be a modern and progressive institution. It’s an ideal we still hold dear today.
When Charles William Wentworth proposed the idea of Australia’s first university in 1850, he imagined “the opportunity for the child of every class to become great and useful in the destinies of this country”.
We’ve stayed true to that original value and purpose by promoting inclusion and diversity for the past 160 years.
It’s the reason that, as early as 1881, we admitted women on an equal footing to male students. The University of Oxford (UK) didn’t follow suit until 30 years later, and Jesus College at The University of Cambridge (UK) did not begin admitting female students until 1974.
It’s also why, from the very start, talented students of all backgrounds were given the chance to access further education through bursaries and scholarships.
Today we offer hundreds of scholarships to support and encourage talented students, and a range of grants and bursaries to those who need a financial helping hand.
The University of Sydney (AU) is an Australian public research university in Sydney, Australia. Founded in 1850, it is Australia’s first university and is regarded as one of the world’s leading universities. The university is known as one of Australia’s six “sandstone universities”. Its campus, spreading across the inner-city suburbs of Camperdown and Darlington, is ranked in the top 10 of the world’s most beautiful universities by the British Daily Telegraph and the American Huffington Post. The university comprises eight academic faculties and university schools, through which it offers bachelor, master and doctoral degrees.
The QS World University Rankings ranked the university as one of the world’s top 25 universities for academic reputation, and high in the world for graduate employability. It is one of the first universities in the world to admit students solely on academic merit, and opened their doors to women on the same basis as men.
Nobel and Crafoord laureates have been affiliated with the university as graduates and faculty. The university has educated Australian prime ministers, governors-general of Australia, state governors and territory administrators, and justices of the High Court of Australia, including chief justices. The university has produced Rhodes Scholars and Gates Scholars.
The University of Sydney (AU) is a member of The Group of Eight (AU), CEMS, The Association of Pacific Rim Universities and The Association of Commonwealth Universities.
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