Standard Presentation Australian Marine Sciences Association Annual Meeting 2023

Assessing the utility of biodegradable substrate for oyster reef restoration in south-eastern Australia (#288)

Kristine M Faelnar 1 , Brendan S Lanham 1 2 , Melanie J Bishop 1
  1. Macquarie University , Sydney, NSW, Australia
  2. University of Melbourne, Parkville, VIC, Australia

Oyster reefs were once a dominant coastal habitat globally but 85% have been lost, largely due to historic overharvest. Along the coast of Australia, oyster reef restoration is scaling up, often with the goal of returning lost habitat, and/or filtration and shoreline stabilisation services. Restoration often involves the addition of a hard base on which oysters can settle and grow. This study investigated the feasibility of using Biodegradable Ecosystem Engineering Elements (BESE-elements), made of potato-starch waste, for oyster reef restoration in eastern-Australia. BESE-elements were deployed at six estuarine sites in New South Wales, with a history of oyster recruitment. It was expected that at all sites, oysters would successfully settle onto the units, and the BESE reefs would enhance invertebrate and fish species richness and abundance. Sampling 1-year post deployment revealed that BESE elements did not support oyster recruitment at all sites. Nevertheless, fish and invertebrate communities at BESE sites showed a change in composition post-deployment, to a community structure intermediate to unmodified control sediments and remnant oyster reefs. While BESE represents a promising substrate for oyster reef restoration, site-specific knowledge of environmental and biological conditions is needed to ensure appropriate application.