This is a guest post by Fam Charko.
The largest sponge transplant project in the world is currently happening right here in Port Phillip Bay. Operation Sponge, a community-led initiative taking place in Blairgowrie, aims to move and re-attach 5,500 wild sponges within the next three months to preserve one of Victoria’s most beautiful dive spots.
On a cold, rainy Sunday in August, I find myself donning a ridiculously thick wetsuit and slipping off a boat berth into the 10-degree water of Port Phillip Bay. ‘Why am I doing this again?’, I ask myself as freezing water creeps down my spine and makes me gasp for breath. I put my scuba regulator in my mouth and descend, forcing my unprotected face into the cold that instantly numbs my cheeks. But I soon realise that it’s worth it. With nothing but the sound of my own breath and bubbles accompanying me, I descend into a temperate underwater wonderland. The drab, grey pier pylons suddenly burst into a wonky version of the rainbow, as I see sponges of many different shapes and sizes growing all over each other, hosting arrays of fragile, nearly transparent bagpipe-shaped sea squirts. Seaweeds are lazily waving their broad leaves in sync with the undulating current. Crusts of bryozoans grow around the base of their stems. I swim past pylon after pylon covered in brightly coloured life forms, fish fleeing before me, hiding in nooks and crannies between the seawall’s wooden panels and huge orange sponges. The whole experience is quite psychedelic.
‘A project like this has never been attempted on this scale before,’ Operation Sponge coordinator AJ Morton says. ‘It has attracted a lot of attention over the last few months, including from people in South Australia and Western Australia who are facing similar issues.’
A few months ago, Dive2U dive school operator AJ and his wife Nicole found out that the Blairgowrie Yacht Squadron was planning to replace the seawall that protects the marina from wave action. The current seawall, which is made of timber, has been weakened to the point of needing replacement by an invasive, wood-boring mollusc called shipworm. Similarly to termites, the shipworm drills into the wood, creating tunnels and hollowing out the structure to the point of disintegration.
Upgrading the seawall, however, also means the destruction of what is arguably Victoria’s most beautiful and popular shore dive site. As the marina is privately owned by the Blairgowrie Yacht Squadron, there are no permits or compulsory mitigating environmental measures required – for example, re-homing the species that live there – and sea life attached to the old timber panels risk being carted off to landfill.
‘Blairgowrie pier is home to an incredible number of sea creatures, attracting Scuba divers from all over Victoria,’ AJ explains. ‘The place is amazing. We have seen many species of nudibranchs, sea stars, red-handed shrimp, spider crabs, all kinds of fish, sea squirts and of course many colourful sponges. We really wanted to preserve this dive site and were racking our brains on how to do this. One night, Nicole and I stayed up very late talking about it, desperate to think of some way we could help. In the early hours of the morning, Nicole suddenly sat up in bed and cried: “I got it! Why don’t we scrape off the sponges, and glue them onto the new wall as it is being built?” ’
Shortly after this eureka moment, Operation Sponge was born. The Mortons did some research and found a special underwater glue that is used by scientists to attach coral onto new substrate. They tested their idea by scraping off a few sponges and sea squirts and gluing them onto a new location. The pilot proved successful: about half of the transplanted animals survived and started growing in their new home immediately.
‘The next step was to come up with a proposal for the Blairgowrie Yacht Squadron and see if they wanted to work together,’ AJ says.
The seawall will be replaced in sections over a period of a few months. The Mortons proposed to deploy volunteer divers from the community, and have them remove sponges from the old panels that will be taken out, then glue them straight onto the new panels that have been put in that week before. Elastic bungee cords strung tightly along the panels keep the glued sponges in place to ensure that they aren’t dislodged by strong wave action until they have attached onto the substrate by themselves. ‘If we do this every weekend for the next few months, we should be able to transplant most of the sponges and preserve the marine life at the site,’ AJ explains.
To their delight, Blairgowrie Yacht Squadron was happy to cooperate and together with the company contracted to do the panel replacements, Aegir Divers, they worked out a strategy. AJ is full of praise for the Yacht Squadron and Aegir Divers: ‘They have been absolutely fantastic. The Yacht Squadron has even donated $1,000 to the project to help with buying the glue and they continue to support us.’
Help is currently coming from all directions; not just from volunteers donating their time, but also through a donation of glue from the glue company itself. This is much-needed sponsorship, as the glue costs $50 for a 300ml tube; AJ estimated that they need about 50L in total. To raise funds for the purchase of more glue, Dive2U has started a crowd funding campaign.
Operation Sponge is exciting not only because it brings the community together; it now also involves scientists who have transformed it into a citizen science project. Kade Mills, a marine scientist who runs Victorian ReefWatch for the Victorian National Parks Association, wasted no time getting stuck into the scientific side of Operation Sponge. ‘When I first found out about the project I thought: what these people are doing is amazing,’ Kade says. ‘If we can ask a few scientific questions, get people involved in doing citizen science and get the results published in a journal for other people to benefit from, then all that time and energy spent by the volunteers would be rewarded.’
Under the pier, I closely examine the newly transplanted sponges, freshly glued to the new panels and supported by the bungee cords that press them onto the timber. On the old seawall, there are many sponge species growing in a seemingly random composition, providing homes, food and breeding places for many other animals, much like coral reefs do. When a sponge is transplanted onto a new structure, it will first attach itself firmly to the substrate. Then it will start spreading in all directions as fast as it can, competing for space with other sponges, algae, seaweeds and tubeworms. Depending on the species, this could take anywhere from two weeks to several months. The encrusting sponges in particular have been observed to be relatively fast growers, covering the new panels quickly, like lichen. Ball sponges and finger sponges may take longer.
Kade is hoping to use simple data collection methods to answer a few questions, such as how many sponges survive the transplanting process initially; how long will it take for the sponges to completely cover the new panels; and what will the species composition of the new wall eventually look like?
The question of survival rates can simply be answered by counting the number of sponges that were transplanted, followed by counting how many survive the process over time. ‘One big advantage for the sponges is that the aspect of the new seawall is exactly the same as that of the old wall,’ Kade explains. ‘Variables like shade, water quality, food abundance, water flow and temperature will all stay the same. The expectation is therefore that sponge survival rates will be relatively high.’
The question of sponge growth rates will be answered using data collected by the volunteers: ‘Anyone with an underwater camera of any description can help. Training time for this is minimal and nobody needs to sit through an hour-long lecture to do this. I’m aiming for the divers to ‘adopt a sponge’, where they regularly visit the same sponges they have transplanted, and take photos of individual sponges at different points in time. We use a simple and free software program that can then calculate the percentage of sponge cover from the photo, eventually showing us the growth rates over time.’
By leaving a few panels bare of sponges, the rates of colonisation between transplanted panels and ‘natural’ panels can be compared. If the panels with transplanted sponges recover faster than the bare panels left to be colonised on their own, this shows that there is merit in doing this work when marine structures elsewhere need to be replaced. It would also be interesting to see if leaving panels bare will favor the establishment of invasive species, rather than natives. ‘The most difficult part of this will be to convince AJ to leave a few panels bare,’ Kade laughs.
The last question is about what the entire ecosystem on the new wall will look like in the end. What sponge species will have successfully established themselves? And will the artificially established sponge garden be as biodiverse as a naturally grown ecosystem? Kade estimates that these last questions will take at least two years to answer. But first things first: there is about 150 metres of seawall that needs its sponges transplanted.
With less than half a scuba tank of air left, I ascend to the surface where AJ helps me out of the water. ‘What do you think?’ he asks me.
‘Amazing,’ I answer, the words coming out slowly as my face muscles defrost. ‘What an amazingly beautiful dive spot. What an amazing project.’
He smiles and says, ‘Only about 5000 sponges to go!’
Cover image by Jacqui Younger