Updated: Sep 29, 2022
Seaweed biofilters that remove nutrients from the waters around the Great Barrier Reef will help protect the reef and contribute to the United Nations Sustainable Development Goal 14: Life Below Water.
Australia's emerging seaweed sector featured as part of the United Nations 2022 Oceans Conference in Lisbon, Portugal at a session outlining how macroalgae contribute to the SDGSDG14 Life Below Water.
Speaking about how work in Australia will contribute to SDG14 was Jo Kelly, a member of the international Safe Seaweed Coalition, CEO of the Australian Sustainable Seaweed Alliance and CEO of the Queensland-based business the Australian Seaweed Institute.
Her presentation was part of an official side event: 'Seaweed: A revolution to achieve SDG 14 and more', which was jointly sponsored by the Australian Seaweed Institute, the Safe Seaweed Coalition and Lloyd's Register Foundation.
Conserve and sustainably use the oceans, seas and marine resources for sustainable development.
In her presentation, Kelly highlighted that seaweed is an emerging industry in Australia, although well-developed globally, mainly in Asia.
"We're looking at how Australia can embrace seaweed as a revolution to improve ocean health," she said.
"The work I lead is focused on seaweed biofilters to protect the Great Barrier Reef. We're working in partnership with the Australian Government and the Great Barrier Reef Foundation on innovation around how purposefully designed, strategically located seaweed aquaculture can act as a biofilter to solve the reef's second biggest problem, which is nitrogen runoff into the Great Barrier Reef area."
Kelly outlined several ways that seaweed biofilters can contribute to SDG 14.
Reducing nutrient pollution
"First of all, nutrient pollution is one of the greatest sources of risk to marine and coastal ecosystems globally. It causes increased algal blooms, poor water quality, eutrophication, acidification, reduces biodiversity and reduces ocean resilience to climate change impacts.
"That's the problem that we've got with the Great Barrier Reef. Seaweed aquaculture provides a really large-scale opportunity to safely soak up that excess nitrogen, phosphorous and carbon that is damaging coastal ecosystems and reefs."
Kelly said a meta-analysis of published data showed that seaweed farms could extract up to 300kgs of nutrients per hectare per year. This demonstrated an effective nature-based solution to help protect coastal ecosystems from nutrient pollution.
Protecting and restoring reef ecosystems
"Protecting and restoring reef ecosystems, that is what we're doing as well. Improving water quality improves the resilience of coral reef ecosystems to reduce things like crown-of-thorns starfish invasions, outbreaks of harmful microalgae, and reducing acidification, which impacts coral calcification rates."
She said establishing seaweed aquaculture for biofiltration might also create a barrier that prevented other extractive industries that could harm the ocean's benthic layer from occurring.
Reducing ocean acidification
"Reducing ocean acidification is a big goal that seaweed aquaculture can contribute to," Kelly said.
"Globally we know that ocean acidification has been increasing because of the absorption of CO2 from the atmosphere. But also, near-shore coastal environments experience more acidic and hypoxic conditions resulting from high nutrient loads in agricultural runoff and other urban runoff that creates microalgal blooms that reduce oxygen.
"The biological impact of increasing acidification is of highest concern on calcifying organisms such as hard corals, coraline algae and shellfish. If corals and other coraline structures are unable to form, then reef ecosystems will be compromised and that obviously impacts on reef resilience in the future."
She said seaweeds would play a key role in ecological resilience. Evidence showed they could buffer seawater acidification at a local level as they sequestered the dissolved carbon. In addition, the photosynthesis process, as a net producer of O2, could assist seawater oxygenation.
"We are modelling the impact of targeted seaweed aquaculture to absorb those nutrients from the seawater and the impact it has on buffering ocean acidification.
"Early modelling has shown that seaweed aquaculture, optimally sited and harvested, can delay the ocean impacts of between 7 and 21 years, which is pretty significant.
"There are a lot of local factors – specific species, biochemistry and hydrodynamics that influence the uptake rate of that. 'We're looking specifically at what happens in our areas, but that can be applied in other areas too."
Kelly highlighted the ecosystem services that purposefully designed and strategically located seaweed agriculture could deliver ecosystem o protect and conserve coastal ecosystems.
"Seaweed regularly harvested removes nutrients from the marine ecosystem, providing sustainable food, animal feed and fertilisers. Bioplastics further reduce environmental impacts on the ocean ecosystem.
"The recent product innovations include a seaweed supplement that reduces methane emissions from cattle by over 80 per cent when sprinkled in their food and edible. Seaweed also provides jobs and economic development for coastal communities."
Kelly said efforts to develop biofilters as a nature-based solution to improve water quality were being undertaken in partnership with government research programs and Indigenous Sea Country people.
"But there are challenges and barriers to scaling up the potential ocean impact that a seaweed industry can have: political will, policy, regulation and investment. These challenges are echoed globally. We need help from international agencies, governments, and funding partners to scale up positive ocean impacts in the decade," Kelly said.
Watch the full session at UN Web TV Seaweed: A revolution to achieve SDG 14 and more