Enclosure 6 - ESP Letter

                                                                              Ecological Service Professionals
                                                                                                         Sustainable Science Solutions


Recommendations
Historical reefs occurred in the Noosa Estuary and have likely declined due to a combination
of overharvesting, sedimentation (due to land use changes) and modifications to coastal
processes in the estuary from training the river mouth and urbanisation of the estuary. This
has resulted in a lack of suitable recruitment surfaces for oysters within the accommodation
space.
Based on available evidence from Florida, historical oyster reefs may have occupied
between 1 and 5% of the accommodation space available in an estuary. In the Noosa
Estuary the accommodation space for oysters would have been restricted to the lower
estuary, based on current ambient environmental conditions (particularly current salinity;
although these may have been historically different due to changes to the river mouth). The
area downstream of site 1 and in the Weyba Creek sub-catchment are consistent with having
water quality conditions suitable for oyster growth.
Current ambient environmental conditions are likely to support natural growth of oysters at
the majority of sites selected given there is sufficient oyster spat, although suitable substrate
that maximises overhanging spaces for natural recruitment needs to be supplemented to
protect spat from smothering from sediment. The easiest way to do this is to provide natural
oyster shell (the preferred settlement surface) at a vertical height above existing sediment,
suitable to allow oysters to grow without becoming smothered by sediment (both shifting
sand banks and accumulation of fine sediment).
We provide the following recommendations based on the current site assessment for each of
the restoration sites proposed:

Site     Recommendation                                              Reason

Site 1   Marginal keep pending successful oyster spat recruitment    Marginal oyster habitat over deep fine sediment on
                                                                     accreting bank. Sediment may not support
         Monitor in accordance with restoration plan, particularly   restoration units
         recruitment and consider removing if oyster spat die
         following settlement                                        Oyster shell not found at site
         Monitor sediment accumulation                               Likely to be at the upstream extent of accommodation
                                                                     space based on limited oyster growth on nearby
                                                                     jetties

Site 2   Keep as per plan – muddy sand bottom                        Oyster shell currently buried at site (historical oyster
                                                                     habitat site), but marginal oyster habitat over fine
         Monitor oyster recruitment & sediment accumulation on       sediment based on current salinity measurements
         restoration units
                                                                     Seagrass observed in close proximity to proposed
         Pre-construction seagrass survey required                   development footprint

Site 3   Keep as per plan – muddy sand bottom                        Oyster shell currently buried at site (historical oyster
                                                                     habitat site), but marginal oyster habitat over fine
         Monitor oyster recruitment & sediment accumulation on       sediment based on current salinity measurements
         restoration units
                                                                     Seagrass observed in close proximity to proposed
         Pre-construction seagrass survey required                   development footprint

Site 4   Keep as per plan – muddy sand bottom                        Optimal zone for oyster growth, within historical oyster
                                                                     harvesting area
         Monitor sediment accumulation on restoration units

Site 5   Keep as per plan – bare sandy bottom                        Optimal zone for oyster growth, within historical oyster
                                                                     harvesting area

Site 6   Keep as per plan – bare sandy mud bottom                    Optimal zone for oyster growth, within historical oyster
                                                                     harvesting area
         Pre-construction seagrass survey required
                                                                     Oyster shell currently buried at site (historical oyster


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