2019-01-14 General Committee Agenda - Attachment 1 to Item 2 - Noosa River Partnership Proposal

The Nature Conservancy


3.0.     OYSTER RESTORATION PROJECT SCOPE

    3.1. Historical significance

The underwater environment of the Noosa River lower estuary was once dominated with
extensive reef ecosystems created primarily by the Australian rock oyster (Saccostrea
glomerata). These reefs provided food and habitat for many other species including
desirable fish species such as whiting, bream and snapper whilst also filtering and
removing nutrients from the water column (a single oyster can filter up to 100 L of water a
day). The reefs were largely lost in the late 1800s to early 1900s primarily as a result of
dredging (which broke up the reef complex) and overharvesting (which removed oyster
biomass) by commercial wild oyster fishers. At the peak of the wild oyster harvest industry
(1906-1907) it is estimated that 2-3 million oysters were harvest in the lower estuary each
year1.

The loss of oyster biomass likely resulted in the ecosystem collapsing, with reefs now
replaced primarily by soft (sandy and muddy) sediments. Changes to the estuary’s
physical-chemical condition, canal development and shoreline armoring have also likely
contributed to the decline of the ecosystem or inhibited its natural recovery. Today, no
oyster reefs exist in the Noosa River estuary despite the presence of individual and small
populations of rock oysters. The closest known intact reef ecosystems occur near North
Stradbroke Island in Morton Bay. Notably, a recent study has identified that the Australian
rock oyster ecosystem is the most threatened marine ecosystem in Australia, with up to
94% of the ecosystem lost throughout Australia since European settlement2.



       3.1.   Project Purpose
       The purpose of this project is to improve the ecological productivity and resilience of the
       Noosa River lower estuary, and the industries and local community that rely on its long-
       term health, by restoring oyster reef ecosystems and thereby increasing biodiversity,
       fish habitat, natural water filtration and amenity value.


       The project will support the implementation of the Noosa River Plan3 particularly
       objectives relating to upholding and improving the ecological resilience and fish life
       within the lower estuary.


       The ecological purpose, or ecosystem goal, is to re-establish a reef ecosystem
       developed by the indigenous rock oyster (Saccostrea glomerata) in the lower estuary.
       Higher levels of biodiversity and biomass, including desirable recreational and
       commercial fish species, are associated with oyster reef ecosystems (in some instances
       up to 500% greater than adjacent soft sediments). The restoration goal is to meet
       ecological community and biomass targets defined during the planning stages of the
       project and adapted from nearby reference sites.


1
  Thurston R. 2015. Historical ecology of the Noosa Estuary fisheries. Report to: Noosa Council, The Nature
Conservancy and The Thomas Foundation (available on request from TNC).
2
  Gillies et al. 2018. Australian Shellfish Ecosystems: past distribution, current status and future management. PLoS
ONE 13(2):e0190914. https://doi.org/10.1371/journal.pone.0190914
3
  Noosa River Plan, Noosa Council, 2019. Http://noosa.qld.gov.au

    Noosa River Partnership                                                                                      Page | 8