Filtering New Life to Port Phillip Bay

Most of us have enjoyed a dish of mussels or oysters at a family Christmas celebration, but many may not know the benefits shellfish provide to their natural habitat or their previous abundance in our very own Port Phillip Bay.

A shellfish reef.  Image: The Nature Conservancy

A shellfish reef. Image: The Nature Conservancy

Like many other places around the world, Port Phillip Bay was once home to a number of temperate habitats including shellfish reefs, soft corals beds, seagrass meadows and salt marshes. Tragically, however, dredging and overfishing have seen a vast depletion of these important habitats. Since the 1800s, native flat oysters were dredged in large numbers for food and for their shells used to make limestone. This practice continued into the 1970s, leaving an estimated 90% reduction of the mussel beds and oyster reefs. Despite the discontinuation of the practice, the populations have never recovered, leading to large portions of the seafloor existing as ghost towns.

Filtering the water column

Shellfish are filter feeders and their ecological importance has not been fully appreciated until recently. Shellfish reefs are essential to the health of marine ecosystems, yet they are seen solely as assets managed by fisheries. They provide a host of ecosystem services including improving water quality, providing a substrate for other species of plant and animal to grow upon, and the creation of habitats that allow other invertebrates to exist. Amazingly, shellfish can filter several bath tubs worth of water a day (up to 150 litres), leading to a reduction in dangerous algal blooms and improving the clarity of water to allow more sunlight to penetrate the depths of the bay. They are also a food source for snapper and other commercially important fish species.

Reefs at risk

The recent report Shellfish Reefs at Risk revealed that shellfish reefs are the most threatened marine habitat on earth. At a global level, 85% of oyster reefs have been completely lost and many of the remaining reefs are functionally extinct. According to the report, shellfish reefs are at less than 10% of prior abundance and wild capture rates of shellfish are down millions of tonnes per year compared with 50 to 100 years ago. 

Baby oysters attached to scallops and mussels for deployment.  Image: ABC / Cameron Best

Baby oysters attached to scallops and mussels for deployment. Image: ABC / Cameron Best

A bright future: Business working with nature

While there appears to be considerable reason for alarm, a new and exciting three-year initiative worth $270,000 is taking place between The Nature Conservancy, Fisheries Victoria and the Albert Park Yachting and Angling Club, which aims to restore Port Phillip Bay’s shellfish reefs. This exciting project is part of a larger Conservancy project called the Great Southern Seascape that hopes to restore a host of marine habitats in South Australian waters. The exciting project was initiated by Fisheries Victoria and the Albert Park Yachting and Angling Club, whose members have identified the loss of productive snapper habitat in and around Hobsons Bay as early as the 1980s.

The first part of this ambitious project seeks to restore shellfish beds to three areas of Port Phillip Bay, including Hobsons Bay (St Kilda), Geelong and Chelsea by attaching up to 40,000 juvenile flat oysters and mussels to empty shells of scallops and limestone beds. I know what you’re thinking: “How many shells are going to be needed to house 40,000 juvenile oysters?” Well, the daunting task of sourcing empty shells has been made considerably easier with the involvement of local brewery Little Creatures that has arranged to donate thousands of their used shells to the project instead of throwing them out. Once collected, the shells get mixed together with lime to create the limestone bedrocks needed as a substrate.

A deployed shellfish reef.  Image: Paul Hamer

A deployed shellfish reef. Image: Paul Hamer

The next step is for divers to place the young oysters and mussels from the hatchery on top of the limestone beds where it is hoped they will settle and successfully establish the reef. If the initial deployment is successful, the reefs will develop into house-sized blocks that will improve the overall health of the bay and increase the populations of octopus, crab, rockling and snapper.

This novel initiative optimistically signifies a fresh relationship between government, environmental groups, and businesses collaborating for a common purpose and paves the way for similar projects to be undertaken. If successful, this will vastly improve the wellbeing of the Bay, as well as create sustainable practices for recreational fishing in the future.

Changing Landscapes: Following the Regent Honeyeater Project

The countryside near Benalla in northern Victoria has been strongly marked by its two centuries of farming and forestry. The logging industries of early settlement have given way to agriculture, and now pastureland spreads like a sea between townships. Speckling the land are a few pockets of heavy, old eucalypts, left behind on roadsides and hard-to-reach hills.


The beautiful regent honeyeater.

The beautiful regent honeyeater.

It’s not easy finding time to speak with Ray Thomas, coordinator of Victoria’s Regent Honeyeater Project. Any spare second he gets is devoted to restoring the ancient forests that once covered the hills and plains around Benalla. Our conversation twice needed rescheduling – some unexpected rain had brought an unmissable opportunity of extra planting.

Acting on small chances like that has clearly paid off. This year, the Regent Honeyeater Project celebrates its 20th year of continuous work in the district, a testament to the tenacity of Ray and his associates. From an initial aim to protect the region’s last fragile remnants of ironbark and box forest, the project has grown in myriad directions: boosting the presence of food trees, to bring migrating birds back to the area; planting wilderness corridors between bushland patches, which allow wildlife movement and prevent inbreeding; a vast network of nest boxes to house rare mammals like the squirrel glider and the brush-tailed phascogale. The program’s eponymous bird has been saved from declining numbers, with wild populations increasing each year.

The project has always relied on the donations and cooperation of landowners: “We started out by cold calling, trying to find and fence the remnant box-ironbark forest around the district.  That was our goal at the start, just to protect these rare, incredibly important fragments.” In Australia’s famously harsh climate, the idea of giving up any agricultural land was a hard sell.

“We saw pretty early on that the program needed to be a part of people’s farms that made sense to them... Everything I was bringing to landowners, I researched and tested beforehand. There was heavy prior investigation. I had to be sure of what I was saying – people can spot hoodwinkery a mile off, they know if you’re trying to put one over on them.”

Our habitat corridors reduce erosion, create windbreaks, and maintain water quality in streams – practical outcomes that mean everybody wins.

Things have changed in two decades, however. A combined space of 1540 hectares of revegetated farmland is showing results: “Now, people are approaching us and asking how they can help. Recently we’ve been getting the choice of what land will be most beneficial for each year. But I still make cold calls, absolutely. There are always areas of land that would help the program, and sometimes people aren’t aware of how important they can be.”

This August, for instance, close cooperation with the owners of an ideal property has allowed the landmark creation of a seed orchard – a carefully choreographed planting that mingles the genes of isolated populations for the first time in decades. Robust and healthy vegetation will be bred from local sources, functioning as a new patch of forest while also providing seedlings for future locations. It’s a vital measure to stave off the effects of inbreeding, which has become so severe in some places that plants are incapable of reproducing.

On the left were seeds collected from a parent group of 50 plants. On the right, from a parent group of 10. They were planted at the same time. Photo: Paul Jones

On the left were seeds collected from a parent group of 50 plants. On the right, from a parent group of 10. They were planted at the same time. Photo: Paul Jones

The RHP team have always had another goal in mind: to work with the community rather than just amongst them. One of the keystone decisions was to bring schoolchildren from Benalla, Wangaratta and the nearby districts to help with planting. For Ray, involving schools was a crucial component of the project’s early design. The goal was to encourage members of the community to begin thinking about their land as early as possible, and to begin taking ownership: “We’ve included school groups from the first year of the project. Year One. There wasn’t much point otherwise – this needs to be bigger than any of us who are on the inside.

There’s a missing age group in volunteering, and it’s just after people are leaving high school. It isn’t always easy being green in a country town - like anyone of that age they’re getting on with other aspects of their life. But the students who help us do remember. Sometimes men and women will see me in the street and say, ‘Ray! You took us planting in high school, remember us? That was a great day!’, referring to a time 10 years ago or more. And then they come back once they’ve got the time.”

Squirrel gliders use the nest boxes set up by the Regent Honeyeater Project team. Image curtesy of the Regent Honeyeater Project. 

Squirrel gliders use the nest boxes set up by the Regent Honeyeater Project team.
Image curtesy of the Regent Honeyeater Project. 

That idea of patient nurturing is central to Ray’s operation: “There’s no point in pushing, or aggressive arguing. One thing we’ve found over the years is that people are ready when they’re ready – they need to decide on their own, and there’s nothing we can say to force that. It’s best for people to digest an idea in their own time. That way when they come to us they’ve chosen to, and it creates longevity and faith in the project.

In any year, we’ll have around 20 schools involved. They need to see the whole program – propagation and planting, and seed collection too. We’ve seen volunteers from school groups coming back on the open weekends. Students from Northcote came to us on a school camp, and later in the spring we had some come back and bring their parents along.”

Of course, there’s no chance to rest on their well-deserved laurels. Monitoring and understanding the benefits of the revegetation is crucial in shaping the future direction of the project. With ever-present restrictions on time, labour and funding, selecting actions with the most benefit is an uncertain business.

“There have been some studies published about the vegetation establishment success rates, and some trapping studies looking at the insects and reptiles using the sites. But they were quite early in the program – sites are less weedy now, with changing bird populations. One of our rarest birds, the grey-crowned babbler, has increased from 50 to 120 birds over the past decade. It’d be great to know more about how they’re using the space.

And our nest boxes – we’ve got years of data collected by volunteers about box occupation. Squirrel gliders and phascogales move through our corridors just four or five years after planting. Our data from this year hasn’t been compiled yet, because we’ve been so busy with growing and planting and collecting. We need to look at how we’re going if we want to be as smart as possible next year.” The next year, next season, is always under scrutiny.

That’s not to say that the project will expand indefinitely: “I think it’s best for us to stick to our patch, and make it the best we can. But you can’t just think about one property or one district. The land doesn’t work like that. A farmer can invest thousands in restoring and maintaining his creek, but unless his neighbour upstream is doing the same, then it doesn’t count for much. We try to get conversations across fences. Landcare groups are starting to band together, to raise bigger voices – ideally we’ll be able to work alongside other groups who are improving their own land, and join at the seams.”

It’s a fair point. While the Regent Honeyeater Project has given us a stalwart example of community achievement, we mustn’t settle into the idea that a few others will do the work. The chance to make a change is open, for anyone who wants to step forward.


If you’re interested in further information, you can visit the Regent Honeyeater website or contact Ray Thomas directly:


Paul works in science education and has been a teaching member of Monash University's Department of Biology since 2010. He is interested in community engagement and sustainable urban development