A Sydney Harbour Research Program initiative led by Dr Ana Bugnot to develop end-of-pipe bioremediation for stormwater pollution has been awarded a City of Sydney Innovation Grant. This is part of our larger research theme of sediment rehabilitation for healthy harbours.

Sydney Harbour provides important socio-economic amenities and supports significant biodiversity, but the health of the Harbour is threatened by pollution. Stormwater discharges represent the main source of contaminants. Stormwater picks up contaminants on its way into the Harbour, which are mostly retained in sediments close to stormwater infrastructure (i.e. drains and canals). In times of heavy rainfall, wastewater overflows can also enter the stormwater system, adding to the cocktail of contaminants. With more extreme weather events predicted under climate change, the likely increase in stormwater runoff and pollution is an imminent threat to waterways. The significant amount of impervious surfaces in the City of Sydney jurisdiction exacerbates the problem of stormwater discharges into Sydney Harbour.

Burrowing animals (i.e. bioturbators) on the seabed play an essential role in the natural remediation of sediment contaminants and associated improvements in water quality. These animals have been mostly lost from Sydney Harbour sediments due to contamination, trampling and overfishing. In other jurisdictions, managers are reintroducing bioturbators at large scales to stimulate sediment processes and improve waterway health, but such strategies have yet to be attempted in Australia.

Remediation of sediments involves dredging out contaminated sediments and replacing them with new, clean sediment. Another strategy includes ‘capping’ contaminated sediments with clean sediments, but this technique is often not applicable to shallow areas. These methods are, however, rarely used as they are expensive and logistically challenging.

This project aims to design a cost-effective method by which the natural remediation capabilities of living organisms are utilise, while restoring the ecological diversity of the Harbour.

Read more here: https://news.cityofsydney.nsw.gov.au/articles/sea-creatures-come-back-to-sydney-harbour