2019-01-14 General Committee Agenda - Attachment 3 to Item 2 - Monitoring of Noosa River Oyster Reefs Nov 2018

Monitoring criteria 2- Natural recruitment processes
Performance objective: Oysters and other sessile benthic invertebrates recruit to reef
restoration units to establish a biogenic matrix, which binds oyster shells in place, prior to
degradation of coir material. The Key Performance Indicators for this are:
    1. Oyster recruitment: successful recruitment of oyster spat in at least 1 out of the 3
        years (i.e. 33% of the time) post deployment (following international best practice of
        40%: Baggett et al. 2015);
    2. Cover of oysters and other sessile benthic invertebrates: an upward trend in the
        cover of sessile benthic invertebrates growing on restoration units; and
    3. Establishment of stable biogenic matrix: structural rigidity of oyster restoration
        units, denoting a stable biogenic matrix after 3 years post deployment, which is
        sufficient to hold oyster shells in place.

Monitoring method: Quantify the recruitment of oysters and other sessile benthic
invertebrates to reef restoration units, and measure changes in the cover of oysters and
other sessile benthic invertebrates over time (following international best practice)(Baggett et
al., 2015). The monitoring methods for each Indicators are:
     1. Oyster recruitment: marked oyster shells will be fastened to the outside of
        restoration units. These shells will be harvested at regular intervals (15 oyster shells
        per location on each event – i.e. 5 shells per unit) and the density and size of recruits
        recorded;
     2. Cover of oysters and other sessile benthic invertebrates: photographs of ten
        quadrats (25 cm x 25cm), distributed in a stratified random design, across each
        oyster reef restoration unit will be taken at regular intervals to quantify the change in
        cover of oysters and other sessile benthic invertebrates (Baggett et al., 2015).
     3. Establishment of stable biogenic matrix: assess the structural integrity of each
        oyster reef restoration unit and monitor the degradation of coir material. Structural
        integrity will be quantified by measuring the proportion of oyster shells (from 10 shells
        that are selected at random at each location), which can be removed easily by hand
        manipulation. The rate of coir degradation will be measured by monitoring changes to
        the condition of coir mesh over time from the ten photo-quadrats, which are collected
        twice per year to assess changes in the cover of benthic invertebrates at each oyster
        reef restoration unit.

Frequency: Every 6 months for a minimum of three years, unless otherwise detailed within
corrective actions

Was the performance objective met?
We identified significant oyster spat settlement and growth at all oyster reefs. Whilst this has
not yet proliferated to cover of oysters on the outside of the restoration units, or to fully
cementing shells within the units together, these positive spat fall and growth results indicate
that these performance criteria are likely to be met in the coming years. Therefore, no further
action is necessary at this early stage of the project.

Supporting evidence
Oyster recruitment
We collected shells from two sources;
     1. 5 shells collected from within the coir bags at each oyster restoration unit (henceforth
         ‘bags’), and
     2. 5 shells collected from ‘oyster necklaces’ which were strings of drilled oyster shells
         tied together with fishing line and then affixed to the top of the oyster restoration units
         during installation (henceforth ‘necklaces’).
All live oysters growing on the shells were identified to species, counted, and their height
measured, and the density of oysters calculated as number of oysters per square meter of
shell (as recommended by Baggett et al., 2015).



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