Dr Ana Bugnot1, Assoc. Prof Katherine Dafforn2, Ms Julia Palmer2, Ms Giulia Filippini2, Ms Katherine Erickson3, Prof. Paul Gribben3
1University of Sydney, Sydney, Australia, 2Macquarie University, Ryde, Australia, 3University of New South Wales, Kensington, Australia
Around 85% of oyster reefs have been lost worldwide, and restoration strategies to recover them are burgeoning. Previous studies have shown that oyster reefs can drive oxygen demand and denitrification in sediments around reefs via the deposition of biodeposits. However, no studies have assessed how oysters affect biodiversity in surrounding sediments, or their role in driving the changes in functioning observed. We studied the biodiversity and function of sediments surrounding four Saccostrea glomerata oyster reefs in the East coast of Australia. We first assessed how biodiversity and sediment characteristics changed at increasing distances from reefs. Sediments close to reefs had consistently greater amounts of labile organic matter, which was positively related to richness and total abundance of infaunal communities. Bioturbation activity was also greater close to reefs, but patterns were variable between and within reefs. A second survey studying how these changes related to sediment function found that sediment oxygen demand and N2 gas release were positively related to bioturbating activity and total bioturbator biomass close to reefs at all sites, while the effect of sediment characteristics was variable between sites. These results indicate that oyster reefs create nearby hotspots of denitrification that are mainly driven by the interactions between oyster reefs and bioturbators. We show for the first time that oyster reefs can affect sediment biodiversity through seascape processes, and highlight the role these interactions play in delivering ecosystems services as a result of restoration strategies.
Biography:
Dr Ana Bugnot completed her Ph.D. at the University of Sydney in 2014. She was a Research Associate at UNSW and in 2018 Ana started a joint Research Associate position at the University of Sydney and Sydney Institute of Marine Science. Ana’s research focusses disentangling the effects of human impacts in the marine environment and investigates strategies to increase ecosystem health. She leads the development of sediment rehabilitation strategies and research informing oyster restoration in collaboration with The Nature Conservancy, DPI Fisheries and OEH NSW.
