Restoration Plan

 

  

   

 

8. Alternative _ o
The principal intent of the project is to restore oyster reef recruitment in the Noosa River to areas that
have historically supported oyster beds, and thereby increase the diversity of fish habitat in the
system.

 

Historical information shows that oyster reefs occurred over substantial areas in the lower reaches of
the Noosa River. These beds have been drastically reduced by unsustainable heavy dredging and
have not recovered naturally in a century. Thus, given the long time that was available for the reefs to
return, and the lack of any natural recovery to date, it is extremely unlikely that oyster beds will
recover naturally in the foreseeable future.

Thus, to return the Noosa River ecosystem to its most probable mix of habitat types and to create a
range of heterogenous and complex fish habitats, there exists no practicable alternative than to
enhance oyster recruitment by providing substrate: this is the reason for this project.

There are no feasible alternatives outside of the Declared Fish Habitat Area A in the Noosa River for
the following three main reasons:

1) The selected restoration sites encompass the area that historically was most likely to have
harboured oyster reefs prior to their destruction in the late 19' and early 20" century
(Thurston 2015), and which has a good current supply of oyster larvae (Figure 3; TNC & ESP
2015).

2) Alternatives in Fish Habitat Management B areas (specifically Lake Doonella) are not suitable
because of the very shallow water body that is frequently highly turbid (caused by wind-driven
suspension of silt and mud) and hence inimical to larval settlement and recruitment (TNC &
ESP 2015),

3) Other areas outside the Declared Fish Habitat Area are important recreation areas, with high
public use, or are navigational channels. It is not practicable to place oyster reef restoration
units in areas that significantly interfere with public access and use or present hazards to
boating.

The planned area of restoration comprises 15 small restoration areas, distributed throughout the
Noosa River according to four main criteria:

1. Encompass the most likely area historically covered by reefs
Historical data show that a minimum of 8,241m? of oyster reefs were removed by dredging
from the lower estuary. Because no fine-scale historical maps exist of oyster reefs, it is
sensible to spread sites to encompass the most likely extent that existed.

2. Oyster Larvae Recruitment
Selected restoration sites encompass the reaches where TNC & ESP (2015) have
demonstrated during a pilot study in 2014/2015, that natural recruitment of larvae is high.

3. Risk Spreading
Vandalism by the general public is possible and this risk can be reduced by dispersing
restoration units over multiple locations.

4. Habitat Connectivity
The value of oyster reefs as fish habitats is enhanced in settings where reefs are functionally
connected (via organism and nutrient movement) to nearby habitats such as mangroves and
seagrass beds. Thus, several sites are located close to, but never inside, mangroves and
seagrass to improve habitat quality.

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