Published on 08 June 2022

Happy World Oceans Day!

Happy World Oceans Day!

Today is an annual United Nations-designated day for raising awareness of the benefits we derive from the ocean, and our individual and collective duty to use its resources sustainably.

To celebrate, Onkaparinga Now brings you the first images—taken by the Department for Environment and Water’s (DEW) Marine Science Team—from the recently completed shellfish reef at O’Sullivan Beach.

The five-hectare reef was completed late last year through a partnership between the Australian Government and its national $20 million Reef Builder initiative, and The Nature Conservancy Australia, with funding also contributed by the City of Onkaparinga.

Shellfish reefs were once abundant throughout Australia and they provided homes, feeding and nursery grounds to hundreds of marine species, but they became threatened with extinction due to overharvesting, pollution and dredging in the late 1800s.

The O’Sullivan Beach reef was constructed in November 2021 from locally sourced limestone and seeded with juvenile, hatchery-raised Australian Flat Oysters, which were settled onto recycled oyster shells.

Over the next few years, these juvenile oysters will grow and recreate a living shellfish reef, providing a home for many marine species.

DEW’s Marine Science Team conducted the first surveys of the O’Sullivan Beach reef recently and photographed it in the early stages of colonisation by macroalgae, invertebrates and fishes.

Juveniles of several species of site-attached reef fish were found on the reef including cryptic weed-fish, which are utilising the shelter of the macroalgae and crevices among the reef boulders.

Ocean encounters

Did you know the waters off the City of Onkaparinga’s coastline are part of the Encounter Marine Park, which boasts an even greater variety of marine life than the Great Barrier Reef? In fact, around 85 per cent of the life found in Southern Australian waters is found nowhere else on Earth. This stunning coastline is an important part of the traditional lands and waters of the Kaurna people.

Scan the horizon

Southern Right Whales migrate from Antarctica from mid-May to September each year to SA’s coast to mate and give birth.

Southern Wright Whales have large tail fins called flukes. These can approximately five metres wide and have a deep notch in the middle. Humpback Whale tails have a jagged edge and are white underneath.

Last year, whales were spotted at Christies Beach, Moana, Sellicks Beach, Seaford/Port Noarlunga South, Port Noarlunga and Port Willunga. You can see the latest whale sightings along SA’s cost at the SA Whale Centre website.

Grab a pair of binoculars and see what else you can spot along the coast, including Great White Sharks, Australian Sea Lions and Bottlenose and Common Dolphins.

Discover an underwater world

The temperate reef systems of Aldinga and Port Noarlunga Reefs lie within a sanctuary zone, helping to protect marine life. The reef is home to over 200 species of marine algae and over 60 species of fish, including Old Wives, Silver Drummers and Sweep. With so much to see, the best way to experience this magical underwater world is by diving or snorkelling.

Port Noarlunga’s a great place for beginners of all ages because there’s a mini reef near the water’s edge to practice at. When you’re confident, you can make your way out to the main reef where you’ll float past schools of fish and find sea stars, colourful sponges and other intricate creatures.

Experienced divers love the Aldinga Reef drop-off accessed by boat, where the reef drops away from five metres to 21 metres, creating a spectacular dive that’s a mass of caverns, crevasses and overhangs where you can see an abundance of marine life.

See if you can spot a Southern Eagle Ray, which can measure up to three-metres; Western Blue Gropers, which live for up to 70 years and grow up to 1.7 metres long; or a Leafy Seadragon, which are South Australia’s marine emblem.

Remember, don’t snorkel or dive alone, do your research, get local advice and assess conditions before taking the plunge.

Care for marine life

We don’t always connect that stormwater from our inland suburbs ends up in local creeks and then flows straight out to see, taking litter with it.

Discarded plastics, cigarette butts, released balloons and food and drink packaging all end up in our waterways and at the beach for us to step on, marine life to ingest, and toxic chemicals to leach into the water.

In fact, a whopping eight-million tonnes of plastic enters the earth’s oceans each year. Litter in oceans and beaches is known as marine debris.

Do your bit

The theme of this year’s World Oceans Day is ‘Revitalisation: Collective Action for the Ocean’ and there are heaps of ways you can help protect our oceans.

  • Reduce the amount of single-use plastics you use.
  • Always use the correct bins and reuse or recycle wherever possible.
  • Never release balloons of any type.
  • Get involved! Volunteer your time and spread the word.

To learn more about Onkaparinga’s incredible coastline and how to get involved, visit the Sustainable Onkaparinga webpage.

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A rock crab sits in a crevice in the new shellfish reef.