Restoring oyster reefs

Those of you who came to the September BIEPA meeting will have heard Robbie Porter from Ozfish.org.au talking about his project to restore shellfish reefs in Moreton Bay. Inspired by Robbie's example of positive action, I invited a bunch of colleagues from work to come down to Ozfish Oyster World at Port of Brisbane, where we had a surprisingly enjoyable and rewarding morning of hard labour on the ROB production line.

These Robust Oyster Baskets (ROBs) are filled with oyster shells, a waste product from the food industry, so that they attract baby oysters (spats) to form new colonies. The steel cages eventually dissolve leaving a new shellfish reef thronging with all kinds of marine life.

Working on the Production Line

While some of us made new baskets using some impressive power-tools, others fed empty oyster shells through Wally the Washer into the empty baskets, and clipped on the lids before stacking them on pallets. The pallets are lined up ready to be transported to a barge, from where they will be taken out to the reef being formed around Fisherman Island.

Educational Tea Break

During our well-deserved tea break, Robbie explained how vital shellfish reefs and oysters in particular are for the health of coastal ecosystems around Australia. Oysters filter a surprising amount of sea water each day; the original extensive oyster reefs around Moreton Bay would have filtered the entire bay about once a week. This kept the water clear for sunlight to reach the seagrass, an essential food for dugongs and turtles. The reefs also provided homes and food for many species of fish and crustaceans.

During the 1800s most of the shellfish reefs around Moreton Bay were destroyed, either for food or to make limestone for the mortar used to build Brisbane city. This has caused water quality and fish stocks to decline dramatically. Seagrass now struggles to grow, and has recently been smothered by silt dumped into the Bay by floods, so that dugongs and turtles are now starving.

Take Positive Action

By restoring the shellfish reefs, the Ozfish project team hope to rebuild fish stocks and improve water quality, which in turn will help seagrass to flourish again, reducing the number of turtles and dugongs that need saving from starvation. It was interesting to learn that while rescuing individual animals is important, saving habitat like this is much more effective in the long run.

I learned a lot from this volunteering opportunity, and will be organising another one with my work colleagues where we take the baskets out on a boat to drop them into the new reef. These things are not difficult to do, and it's very rewarding to be doing something practical to restore vital ecosystems.

If you are interested in volunteering for Ozfish events, head over to the events page on their website to register.

New BIEPA Team

We are currently exploring options for setting up a BIEPA💙Ozfish team, led by Peter Alexander and aided by Robbie Porter, who will work on restoring shellfish reefs in Pumicestone Passage and monitoring water quality to measure the impact. This would build upon the prior efforts of Dr Ben Diggles and take advantage of recent legislation changes that we hope will make it easier to do this around Bribie.

Contact me at mike@biepa.online if you're interested in joining this team.