Quick-fire questions with Adriana from Operation Crayweed

1) What’s the environmental impact of the current work – what’s the carbon capture, research impact etc.

Impact of Operation Crayweed to date:

• Operation Crayweed is considered Australia’s most successful seaweed restoration project to date
• We have reversed local extinction of crayweed in Sydney and re-established crayweed forests in 7 reefs, representing about 8,000 m2 restored (and continuing to expand)
• Restoration of crayweed forests also re-establishes ecological communities of the tiny ‘epifauna’ that live in and among the crayweed, which are themselves a source of food for fish and invertebrates.
• We have inspired new restoration efforts nationally and internationally, e.g. for bull kelp restoration in the USA and NZ or Cystoseira forests in the Mediterranean
• Our work has greatly enhanced public awareness about the importance of seaweed forests and the role of science working in collaboration with local communities in facilitating recovery:
  • We engage hundreds of people per year with hands-on restoration via our community planting days
  • We connect with thousands of people per month via our website and social media sites (Facebook, Instagram, Twitter)
  • Our educational activities reach thousands of children via in-person workshops in schools, online games and online resources (e.g. ABC’s “Deep Dive into Australia’s Ocean Odyssey” an educational set of resources targeting secondary students and short videos e.g.  ‘What’s something cool about seaweed?’, viewed >7,100 times.
• Our work has led to 15 scientific articles published in top peer-reviewed international scientific journals, which have been cited > 400 times in other scientific publications
• Capacity building: through our restoration we have trained 3 BSc Honours students and 2 PhD students, with another 2 students currently working on their theses

2) Can you tell us a bot more about carbon capture?

We estimate that crayweed sequesters about 400 kg of carbon per hectare per year. This is based on broad estimates rather than direct quantification, which is tricky.

Some broader figures: Australia’s kelp forests are highly productive and contain between 10 and 22 million tonnes of carbon. Estimated carbon sequestration values of our seaweed forests continent-wide are between 1 and 3 million tonnes of carbon per year.

The issue is that seaweed carbon is not sequestered locally, as seaweeds grow on rocks (not on sediment where carbon can accumulate). Instead, the carbon sequestration values are from biomass that becomes detached and ends up in the deep sea. This makes it trickier to estimate and validate carbon sequestration by seaweeds, and some of the science is being developed. Hence at the moment, seaweed forests are not formally included in Blue Carbon estimates by the Commonwealth (which does include seagrasses, tidal marshes and mangroves).

3) How is 50K spent? What’s the environmental impact of one site worth 50K. For eg. Is it 10000 x of Carbon out of the atmosphere per year?

The costs associated with crayweed restoration are for staff, boating, diving and community engagement activities (workshops, artist collaborations).

Ziggy and myself are employed full time by our respective universities (UNSW and the University of Sydney) and provide our time in-kind, but we need a set number of divers, skippers and assistants to comply with work health and safety regulations when it comes to SCUBA diving.

With regards to the environmental impact of one site, it’s important to understand how our general approach works. We don’t manually restore an entire reef, but rather introduce small patches with the right mixture of male and female individuals which act as a ‘seeding source’. We initially plant patches of about 20 – 80 m2 by bringing in crayweed from nearby reefs outside of Sydney (north of Palm Beach, south of Cronulla). These crayweed reproduce straight away and we start seeing offspring after about 6-9 months. We often do repeated plantings in one way as there is also a bit of loss of individual crayweed due to storms or urchins/ fish munching on them. After about a year, the population expands in a self-sustaining way.

Depending on what area we plant, we can expect one site to reach half a hectare in ~ 5 to 10 years, which would correspond to ~ 200 kg carbon.