2020-07-07 P&E Agenda - Item 3 - Attachment 1 - TNC Project Management Plan

6. Objective Four: Shellfish restoration

6.1 Purpose and deliverables

The purpose of this objective is to restore shellfish (native rock oyster-dominated) ecosystems in the Noosa River
estuary. This objective is the primary in-water conservation outcome of the overall TNC-NSC Project. The deliverables
associated with the objective are:

•    (A4.1) Restoration at two sites (approx. 40m-50m shore length of substrate laid, per site) which tests substrate
     selection, deployment techniques, in-situ substrate configurations, system efficiencies as well as oyster growth
     and survival.
•    (A4.2) Restoration across multiple sites, as determined by restoration suitability modelling and outcomes of
     community consultation.
•    (A4.3) Monitoring and evaluation study for both pilot and full restoration sites. Monitoring to include oyster
     metrics, invertebrates and fish use (detailed in MER Plan).

A more extensive overview of the restoration process and rationale is provided below.

6.2 Background to shellfish ecosystems and rationale for restoration

Shellfish ecosystems are intertidal or subtidal three-dimensional ecosystems formed by oysters, razorfish and/or
mussels at high densities 4 . Shellfish ecosystems can vary in appearance depending on the dominant ecosystem-
forming species. Common attributes of shellfish ecosystems include:

     •     High (i.e. reefs) and low (i.e. beds) hard biogenic substrates, created by oysters and/or mussels, on
           otherwise soft sediment or rocky areas, which are often interspersed with sand/silt or rubble matches
           and/or seagrass;
     •     Provision of habitat and refuge for other species including sessile and mobile organisms, and thereby
           supporting high levels of species diversity and unique assemblages;
     •     Accreting dead shell material, such that the shellfish ecosystem grows in size and mass over time; and
     •     Provision of food for other organisms, either when consumed directly or through the species assemblages
           they support.

Shellfish are ecosystem engineers, providing important habitat for many species of finfish (e.g. snapper and whiting),
elasmobranchs (e.g. stingrays) and invertebrates (e.g. shrimps and crabs) through their high structural complexity,
including for many important recreational and commercial fishery species. Additionally, shellfish ecosystems provide
water filtration, sediment stabilization and the transfer of nutrients from the water column to the surrounding
community, as well as enhanced removal of potentially damaging nutrients through processes such as denitrification.

6.3 Shellfish ecosystem loss and historical significance in the Noosa Estuary

The underwater environment of the lower estuary in the Noosa River was once dominated with extensive shellfish
ecosystems created primarily by the Australian rock oyster (Saccostrea glomerata). These ecosystems 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. Oyster

4 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


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         BRING BACK THE FISH: PROJECT MANAGEMENT PLAN