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Enclosure 6 - ESP Letter
Attached to the e-mail Operational Works Application OPW17/0016.
Attached to the e-mail Enclosure 5-Restoration Plan.eml, inside Operational Works Application OPW17/0016.
Ecological Service Professionals
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Cherie O’Sullivan Our Reference: L1533.3
Environment Officer
Noosa Council
PO Box 141,
Tewantin, QLD, 4565
7 November 2016
RE: Assessment of Oyster Habitat in Noosa River Estuary
Dear Cherie,
Thank you for the opportunity to assist Noosa Parks Association and Council to provide a
preliminary assessment of the location of current and historical oyster reefs in the Noosa
River Estuary. Please find below our advice based on a desktop review of information
available and a 2-day field assessment on the 25th and 26th of October 2016.
Executive Summary
The purpose of this report is to demonstrate to fisheries that the proposal to install oyster reef
recruitment units in a Resource Allocation Area of 90 m2 at each of 16 sites (i.e. covering a
total maximum surface area of 1440 m2) will represent restoration of habitat that existed
historically in the Noosa River Estuary but was removed by early settlers and will not result in
the substitution of sand habitats with oyster reef habitat types. This has been demonstrated
through: a historical assessment of the presence of oysters; calculation of live oyster harvest
area (based on reported oyster densities); field assessments of current environmental
conditions (water temperature, salinity, pH, dissolved oxygen and turbidity); and, a field
assessment of the presence of areas where oysters naturally grow.
Oyster reefs are in decline globally due to a range of factors including historical
overharvesting and degradation of estuarine habitat. Oyster reefs elsewhere in world, in
estuaries that also contain everglades, typically cover 1 - 5% of the accommodation space
(area suitable for oyster growth) in an estuary.
Historical oyster reefs were present in the Noosa Estuary as evidenced by past fisheries
records and other historical accounts including indigenous knowledge.
Conservative estimates of the number of live oysters harvested in the early 1900s and
current densities of oyster reefs measured in the USA were used to extrapolate the
maximum area of live oyster harvested in Noosa in the early 1900s, which conservatively
was 8241 m2 to meet the peak harvest demand. This does not include removal of dead shell
for construction purposes.
Current water quality parameters (primarily temperature and salinity) are most suitable for
oyster growth at sites downstream of approximately site 2 in the main Noosa River Channel,
in Lake Weyba and Weyba Creek. Although conditions could be tolerated by rock oysters at
all sites.
A| PO Box 5815 Manly QLD 4179 T| +61 428 118 496 E| [email protected] W| ecosp.com.au ABN| 84 169 274 391
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Several dead oyster shell beds were recorded at or below the sediment surface. The lack of
vertical height above the sediment, suitable surface orientations (lack of overhanging
surfaces) and high mobility/accumulation of fine sediment is likely to contribute to the low
numbers of live oysters currently growing in these areas.
Living oyster aggregations were found in the Noosa Estuary only where hard surfaces
protruded from the sediment or on hard surfaces where fine sediment could not settle (i.e. on
vertical surfaces or those in the intertidal where wave action removes fine sediment).
One living leaf oyster (a large flat oyster species which can provide substrate for rock
oysters) bed of 4050m2 was recorded in Weyba Creek.
Based on field observations, a suitable way to assist restoration of habitat is to reintroduce
dead shell (a preferred settlement surface) at a suitable vertical height on the shore (above
LAT) and with sufficient vertical relief to mimic natural oyster reefs (i.e. >0.5 m). Abundant
oyster shell was historically used by oyster cultivators to stabilise banks and improve the
productivity of oyster harvesting areas. Therefore, creating restoration structures with
suitable overhanging surfaces, at a sufficient height on the shore (above LAT as this is where
most oysters currently grow), with sufficient vertical height above the surface (i.e. >0.5m) and
stabilisation of sediment has a high likelihood of success.
The proposed total Resource Allocation Area for oyster restoration is 1440 m2, which
combined with the existing leaf oyster bed (4050 m2) and oyster aggregations on rock rubble
(16,597 m2), represents <54% of areas likely to contain oyster beds or reefs in the Noosa
estuary based on 1% of the accommodation space (area with ambient water quality
conditions suitable for oyster growth) within historical oyster lease areas.
We understand that all restoration is to be completed on bare sediment. Based on an
assessment of the likely historical extent, location within the estuary, current ambient
environmental conditions, presence of oyster spat and the presence of adult oysters on
nearby hard substrate, the proposed restoration effort would not represent substitution of
bare sand habitat. Instead it would restore a natural habitat where oysters were once
abundant (but now often buried under sand and silt, or likely to occur but habitat was
removed through dredging).
Background
It is estimated that globally, the biogenic reef habitat (i.e. habitat produced by living
organisms) formed by oysters in estuaries has declined by up to 85% of historical extent and
is functionally extinct in many estuaries, particularly along the east coast of Australia (Beck et
al. 2011). Biogenic oyster habitat forms when oysters aggregate on soft sediment or hard
surfaces, in the lower intertidal and subtidal areas of estuaries. Biogenic oyster habitats are
classified into three types according to Beck et al. (2009):
1) Oyster reefs are formed where oysters are the dominant structural component, and can
provide up to 0.5 m of vertical height above the surrounding sediment surface.
2) Oyster beds are formed where oysters aggregate in high densities, are the dominant
structural component, but provide less than 0.5 m in vertical height
3) Oyster aggregations grow on underlying hard structures (i.e. bedrock, rocky rubble, and
mangrove pneumatophores).
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The presence of oyster spat, optimal salinity, temperature, good tidal/water movement, and
suitable surfaces for oyster spat to settle are key drivers of the distribution of oyster
dominated habitats in an estuary (Volety et al. 2014). Suitable substrate includes hard
surfaces (old shell, rubble/gravel, coffee rock, bedrock) areas with complex three-
dimensional structure with various small spaces for oyster spat to settle, with over, hanging
and vertical surfaces shown to maximise oyster spat settlement (TNC & ESP 2015). Healthy
functional estuaries in Florida on the east coast of the USA (that also have everglades and
occur at a similar latitude in the northern hemisphere) have between 1-5% oyster coverage
of the accommodation space (i.e. the area within the estuary with suitable conditions for
oyster growth) (Volety 2013). Due to the degradation of oyster dominated habitats, this value
provides a good estimate of the potential area historically occupied by oyster habitats in the
Noosa Estuary prior to commercial harvesting.
In terms of habitat provision, oyster reefs provide three-dimensional habitat that can have up
to 50 times more surface area than an equivalent size of bare sand or mud (MDCA 2006).
The crevices and spaces between oysters create important places for a variety of small
organisms to live away from competition with fast growing algae (including oyster spat,
crabs, worms, snails, sea squirts, sponges and fish). The productivity of restored oyster
habitats can also drive increased diversity and biomass of commercially and recreationally
important species such as fish and crabs relative to bare sediment (Grabowski et al. 2005;
Peterson et al. 2003). The positive benefits that oyster reefs provide has led to the
recognition of shellfish reefs as an important wetland habitat type in the Convention on
Wetlands of International Importance (The Ramsar Convention – habitat type ‘Ga’) (Kasoar
et al. 2015). Oyster reefs provide a variety of ecosystem functions include providing habitat
for recreationally and commercially important fisheries; stabilisation of sediment and
shoreline protection, diversification of habitat types in the seascape, water quality
improvement, carbon sequestration and oyster production (Grabawski et al. 2012). A key
function of restored oyster reefs and beds may be local stabilisation of soft sediment habitats
and filtering of estuarine water. Oyster reefs have the potential to provide substantial
benefits worth up to US$99,000 ha-1 year-1, through the ecological functions they provide
(Grabawski et al. 2012).
Estuarine habitats such as oyster reefs and beds, seagrass beds and mangrove forests can
regrow naturally following disturbance where conditions are suitable and there are sufficient
recruits/propagules/seeds available. Unfortunately, due to the removal of conch (dead shell)
beds in the Noosa Estuary (references cited in Thurstan 2015), current conditions limit
natural regrowth of oyster reefs primarily due to a lack of suitable substrate within the
accommodation space. Areas that may be suitable for oysters to grow are now dominated by
mobile sediments which can smother oyster spat before they can grow to a size large
enough to survive. A similar issue occurs for mangrove habitats where bank erosion creates
unfavourable conditions for propagule survival. Restoration of mangroves on eroding banks
usually requires human intervention to stabilise banks and remove wave action, followed by
natural or assisted reseeding by mangrove propagules.
Marine plant restoration within a Fish Habitat Area is well established and community driven
projects can be achieved through self-assessable codes and various exemptions of the
legislation. However, currently the mechanisms to facilitate holistic restoration of seascapes
or the natural restoration of oyster habitat are not recognised within this legislation (despite
shellfish being recognised as a wetland habitat type under Ramsar Legislation in the same
way as mangroves, seagrass and saltmarsh). Sixteen sites have been identified as potential
areas for oyster reef restoration throughout the lower Noosa River Estuary (which is subject
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to a current Resource Allocation Authority and Development Application to restore lost oyster
reef habitat through the QLD Government). The aim of this restoration project is to restore
the complexity of habitat in the estuarine seascape.
Assessment Method
1. A desktop study was completed to describe the historical status of oyster reefs in the
Noosa River Estuary, to provide a context for the field survey results and identify areas that
may be suitable for oyster growth. This mostly relied on the existing work compiled by Ruth
Thurstan, supplemented by other available reports / data where available. The desktop
assessment informed suitable locations to be visited in the field survey to confirm the
presence of oyster beds or reefs.
2. A field survey was completed on the 25th and 26th of October 2016 by Dr Simon Walker
(ESP) and Bryan Walsh (NPA), to provide a preliminary assessment and map of the extent of
oyster reef, bed and aggregation habitat in the lower estuary. Our assessment of the
substrate type was made at several locations within the estuary (largely focussed on areas
known to have hard substrate or sites proposed in Council’s Resource Allocation Authority).
Visual assessments were completed either from a boat, on foot or snorkel (in areas of poor
visibility) using an underwater video camera. The presence of dead shell or living oysters,
hard substrate or marine plants (primarily seagrass and macroalgae) were extent was
recorded using GPS. The extent of seagrass was interpolated from satellite imagery of the
area and field validated using a series of spot checks with a boat deployed camera or on
snorkel. The full extent of seagrass in the estuary was not mapped. The following habitat
categories were used in our assessment:
Table 1 Habitat category descriptions
Habitat Brief Habitat Description
Category
Shell bed Aggregation of dead shell (conch) on the surface of sediment, including a dead shell from variety of species such
as oysters, clams and snails.
Oyster A dense aggregation of leaf oysters in low relief (<0.5 m) growing on soft sediment surface and providing
Bed substrate for rock oysters and other sessile organisms to survive (Beck et al. 2009).
Oyster A dense aggregation of oysters growing on dead oyster shell on soft sediment with high vertical relief (>0.5 m)
Reef above sediment surface (Beck et al. 2009).
Rubble Predominantly rocky rubble, gravel, pebbles and boulders protruding from the sediment surface, with oysters
Bank aggregating on the surface or dead shell surrounding rock.
Rocky Predominantly hard rock shelf protruding from the sediment surface, with oysters aggregating on the surface of
Reef rocks.
Coffee Predominantly coffee rock shelf protruding from the sediment surface, with sparse oysters growing on surface.
Rock Reef
Seagrass Seagrass beds varied from 5 to >90% coverage, including Zostera mulleri, Halophila ovalis and Halodule spp..
beds
The extent of habitat was identified visually and mapped with a hand held GPS. A map
showing the areas searched is provided in Appendix A.
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Assessing the Presence of Smothered Oyster Beds
To assess for the presence of hard substrate (rock, rubble or shell grit) beneath soft
sediment, we probed bare substrate in at least 5 points at each of the 16 sites to determine
the extent of buried oyster shell if present and at several other locations throughout the
estuary where oyster rubble was detected on the camera or where oysters were found along
the shoreline. Probing of the sediment was completed using a narrow 2.4 m (1 cm wide)
Kevlar probe to determine whether hard substrate or shell/rubble layer could be located
below the sediment surface. The depth of sediment overlying these layers was recorded
where hard surfaces were detected (Table Appendix A).
Due to time constraints, our survey was limited to areas:
1) along the main Noosa River channel from Hays Island to 715 m upstream of the
Tewantin Ferry;
2) areas known to have rocks based on boating charts in Lake Weyba; and
3) along the main channel of Weyba Creek.
In situ Water Quality
We also assessed the water quality at each of the sites identified in the RAA along the
estuary using a YSI ProDSS multi-parameter water quality sonde. The probe was calibrated
prior to going into the field and the following parameters were assessed: temperature (°C);
salinity (PSU); conductivity (µS/cm); dissolved oxygen (mg/L & % saturation); turbidity (NTU);
pH & depth (m).
Limitations
These preliminary assessments were qualitative in nature and additional work would be
required to assess the density of live oysters and to confirm the full extent of historical oyster
beds and the depth of oyster shell or rubble present along the estuary that is currently buried
under fine sediment. A targeted assessment, including sediment coring, could be used to
identify the density of historical oyster shell that remains in the system (i.e. that was not
removed for lime and road base) in areas not assessed in this report. Carbon dating could
be used to determine the age of oysters below the sediment surface which could be used to
recreate a historical account of change in the sediment budget of the Noosa Estuary,
although this information would be useful for the long-term restoration of the Noosa Estuary,
it is not critical to inform the proposed restoration project, and is considered excessive for the
scale of proposed restoration works. The methods provide in this report present an adequate
and conservative determination of the minimum surface area and location of historical oyster
habitat in the Noosa Estuary.
Historical Account of Oysters in Noosa River Estuary
Oysters were a food source for the Kabi Kabi traditional owners, who provide the first record
of the Noosa Estuary. Historical newspaper accounts of the density of oysters in the Noosa
Estuary indicate that there were plentiful oysters with remnants found in middens around
Tewantin to a depth of approximately 4 m, evidence of a substantial and sustained source of
food.
“Oysters are very plentiful, but are, I am told, gradually being killed by the pearl-bearing
species, which here are of no commercial value. The banks of the river at Tewantin, for a
depth of 12 or 13 feet, are entirely composed of oyster shells, which have no doubt been
accumulated by the blacks, charcoal and stone tomahawks having been found 6ft below the
surface.” Australian Town and Country Journal, 29 Apr 1882 (cited in Thurstan 2015).
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The presence of extensive oyster banks through the lower estuary including previously on
Hays Island is further supported by a more recent quote from the Nambour Chronical (Cited
in Thurstan 2015).
“The [midden] is at Hay's Island at Noosa Heads where a heap of oyster shells rising on a
small piece of elevated ground amongst the mangroves bears testimony to the feeding habits
of the former natives of the Noosa River estuary. An effort should be made to preserve this
small piece of history when the development of Hay's Island eventually takes place, before it
becomes buried or torn apart by the sand pumps and bulldozers...” Nambour Chronicle, 9
Feb 1967.
An existing hand drawn map from the fisheries inspector in 1934, shows the presence of
historical oyster leases in the Noosa River and Weyba Creek (Figure 1: Thurstan 2015).
Figure 1 Sketch drawn by the Fisheries Inspector in 1934 highlighting the areas in the Noosa
River closed to net fishing. The red numbers indicate the Noosa oyster sections at the
time. Source: Queensland State Archives.
A historical photo of intertidal oyster beds from Moreton Bay (Figure 2) and an oyster reef
from Keppel Bay (Figure 3), demonstrates that where ambient conditions were suitable,
oyster habitats historically covered vast areas of the intertidal area in Southern Queensland
estuaries. There are no historical photos of subtidal reefs available due to a lack of suitable
technology at the time to record these. Oysters have been located growing in dense
aggregations on mangroves on Moreton Island on sand (Figure 4). Oyster aggregations
have also been found on rock, rubble and on artificial surfaces in the Noosa estuary as
outlined below.
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Figure 2 Historical photo of an intertidal oyster bed at Toorbul Point, QLD circa 1906 (Smith
1985)
Figure 3 Historical photo of an oyster reef from Keppel Bay, note dense aggregation of oysters
and high vertical relief above sediment (Saville-Kent 1891)
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Figure 4 Dense oyster aggregation on intertidal mangroves in Moreton Bay
A variety of oyster species are likely to occur in the Noosa Estuary due to the warm waters
and proximity to tropical latitudes (the exact distribution of many oyster species in Australia is
currently unknown) (Nell 2001). Species known or likely to occur in the estuary include the
Sydney rock oyster (Saccostrea glomerata), milky oyster (Saccostrea cucullata), black lip
oyster (Saccostrea echinata), palmate oyster (Planostrea pestigris), leaf oyster (Isognomon
ephippium), and pearl oysters (Pinctata maculata) among others (Nell 2001; Thurstan 2015;
TNC & ESP 2015 and personal observations). A more detailed understanding of the
diversity of oyster species occurring in the Noosa Estuary will be a good scientific outcome of
the proposed restoration project, which would contribute to objective 4 of the Fish Habitat
Research & Management Program (DAF 2016).
Estimate of the Historical Extent of Oyster Banks in Noosa Estuary
It is estimated that the majority of oysters harvested historically from South East Queensland
came from intertidal and shallow banks, with approximately 20% coming from dredging of
subtidal reefs (Smith 1981). Oysters were collected intertidally or dredged from Noosa River
channel and shipped to areas in Pumicestone Passage and the Broadwater further south for
fattening prior to sending to market (Smith 1981). Traditionally, oyster cultivators in Moreton
Bay used a variety of readily available substrates including dead oyster shell, broken tiles
and sand to firm up the ground and increase the productivity of their beds (Smith 1981).
Based on historical reports of the quantity of oysters harvested from the Noosa Estuary in the
early 1900s (Marine Department Reports 1905; 1906 cited in Thurstan 2015), it is estimated
that between 2 and 3 million oysters were removed each year in 1905 and 1906 and that up
to 4000 bags annually (4 to 6 million oysters) were transported south from Noosa Estuary by
the Moreton Bay Oyster Company at the peak of the industry, until the 1930s. A historical
photo from 1908 of oysterman with bagged live oysters in Moreton Bay is provided to
illustrate the size of each bag used to transport oysters (Figure 6). Records of the actual size
of oyster harvested are limited, but conservatively, each live oyster was likely to be 5 cm long
when dredged and sent to Moreton Bay to grow to marketable size (oysters 5 cm in length
are considered too small in today’s commercial market and are returned to continue growing
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DAF 2009). These estimates do not account for the quantity of dead oyster shell (conch)
removed from the estuary and used for road base or burnt to create lime for cement.
Removing this dead shell would have destabilised the sediment in the estuary and limited
subsequent recruitment onto the remaining oyster banks.
Due to the degradation of these oyster habitats, we currently do not know the natural density
of intertidal or subtidal oyster habitats in the Noosa estuary. However, the average
maximum density of oyster reefs recorded in the USA is 728 ± 102 ind. m-2 for a restored
oyster reef 3 years post deployment (Casas et al. 2015). Therefore, if similar maximum
densities recorded elsewhere also occurred in the Noosa estuary (i.e. 728 ind. m-2) at the
maximum harvest rates (i.e. 6 million oysters per year), then a conservative annual harvest
area of live oysters of 8,241 m2 (but up to 9585 m2 at peak harvest and if density was at the
lower end 626 ind. m-2) would have been required to be dredged or hand harvest to meet the
live oyster harvest records each year, not including dead oysters taken (which were not
recorded). Mechanical dredging, which occurred in the Noosa estuary, usually occurs when
hand harvesting is no longer a viable harvest option due to decreased oyster densities
(Smith 1981). An example of the dredge sled used is provided in Figure 5. Therefore, at the
time when oysters were dredged in the Noosa estuary, the density of oysters was likely much
lower than the maximum 728 ± 102 ind. m-2 recorded elsewhere, so the dredged footprint
was likely much greater than estimated here. Conservative estimates have been used
throughout to ensure that the amount of oyster habitat restored would not substitute habitat
other important habitats within the Fish Habitat Area.
Figure 5 Historical dredge used from a boat to harvest subtidal oysters (circa 1910) (Smith
1985).
Furthermore, the current time required to reach marketable commercial size is approximately
2-3 years (DAF 2009), which means that particular leases would likely not have been
dredged more than once every two or three years (a plausible reason the Moreton Bay
Oyster Company initially had three oyster areas in Noosa River to rotate the harvest through
each area), so logically, the actual area harvested was likely much greater than 3 times the
maximum area of live oyster to meet annual harvest demand. A key assumption is that only
live oysters were transported in bags rather than vast quantities of dead shell used for other
purposes. Therefore, the actual biogenic oyster habitat historically present in Noosa Estuary
would have been greater than estimated here.
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By the late 1930s, the oyster fishery harvest in Southeast Queensland, including Noosa
Estuary, went into depression (Smith 1981). Ultimately it is thought the natural oyster banks
were unable to recover due to both the removal of live oysters and dead shell from the
Noosa system (Monks 2000, cited in Thurstan 2015; Smith 1985). Declining water quality
resulting in recruitment failure of oyster spat and disease has also been implicated in the
general decline of oyster banks in Moreton Bay (Diggles 2013).
Figure 6 Historical photo showing the large size of bagged oysters in 1908 (Smith 1981).
Identifying Current Oyster Accommodation Space
The accommodation space represents the area in an estuary with environmental conditions
suitable for growth of oysters (Volety 2013). Oysters grow from the intertidal to depths of at
least 20 metres and this is where much of the hand gathering or dredging of oysters has
historically occurred (Nell 2001). However, it is thought that due to changes in ambient
conditions and a variety of external factors, rock oysters in Southern Queensland are
typically found only in the intertidal zone and have been functionally lost from subtidal
habitats (Diggles 2013). Conditions suitable for optimal oyster growth are summarised in
Table 2, from Nell & Halliday (1988), Halliday (1995) and Rubio (2007).
Table 2 Temperature and salinity for optimum growth and tolerance limit
Parameter Units Life History Stage
Larvae Spat Adult
Temperature optimum growth °C 24-26 14-28 18-26
Temperature tolerance limit °C unknown 11-30 11-30
Salinity optimum growth ppt 23-39 20-40 25-35
Salinity tolerance limit ppt 15-39 0-40 0-50
Adult rock oysters are able to close their valve for several days if salinity is less than 15 ppt,
although prolonged periods of low salinity can cause death (Nell & Halliday 1988; Halliday
1995).
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Water quality was assessed at 10 sites throughout the Noosa River Estuary in October 2016
to determine potentially suitable conditions for oyster growth. The location of sites surveyed
and reaches in the estuary are shown in Figure 7. Salinity was lowest (21.54 psu) at the most
upstream site (site 1), and highest in Lake Weyba (sites 16 & 17 approximately 35.5 psu;
Figure 24). Salinity at the site closest to the mouth of the estuary (site 10) was only
29.82 psu (Figure 8). Decreased salinity in the estuary could be due to complex hydrological
interactions between tidal and freshwater surface and groundwater flows. The other water
quality parameters measured were typically more similar among the sites assessed (Table
3). Oysters were found growing at turbidity concentrations less than 15 NTU, although
resuspension of fine sediment particles reduced oyster aggregation density at those sites
(i.e. site 17).
Table 3 Water quality results from the Noosa Estuary
Parameter Units Site
1 2 3 5 6 10 11 12 16 17
Time sampled 1536 1550 1608 1625 1506 1321 1358 1347 1103 1024
Date sampled 26/10 26/10 26/10 25/10 25/10 25/10 26/10 26/10 26/10 26/10
Tidal state flood flood flood flood flood flood flood flood ebb ebb
Temperature °C 25.6 25.4 24.9 25 26.1 24.6 25.1 25.8 26.8 24.1
Salinity PSU 21.54 22.73 23.46 29.51 26.72 29.82 33.07 33.21 35.58 35.53
Conductivity µS/cm 34325 36050 37076 46100 41701 45949 50471 50670 53913 53766
Dissolved Oxygen mg/L 7.8 7.7 7.55 7.53 7.81 7.3 7.33 7.67 7.22 6.79
Dissolved Oxygen % Sat. 108 106.7 104.1 107.7 112.1 104 107.2 113.6 110.2 99.6
Turbidity NTU 7.1 10.8 4.3 1.9 4.4 2 2.3 10.4 5.7 15
pH pH units 8.03 8.04 8.03 8.06 8.07 8.01 8.06 8.07 8.07 8.04
Grey cells indicate current ambient conditions in October 2016 that were below current optimal oyster growth limits, although
adult oysters can tolerate salinity this low and were found growing in low densities on nearby coffee rock reefs which indicates
that oysters can grow there if suitable habitat is provided.
An assessment of the accommodation space in the Noosa River (based on measurements
taken in October) demonstrates that there are current ambient environmental conditions
(temperature, salinity and depth) suitable for oyster growth; however, the availability of hard
substrate (dead shell beds, rubble, bedrock) is lacking, particularly in areas that would allow
the natural formation of oyster beds or reefs due to smothering from sediment, among other
factors.
Current Distribution of Oyster Reefs
Based on field observations in October 2016, the predominant habitat in the lower Noosa
Estuary is soft sediment (a mix of sand, mud and clay to varying proportions depending on
the position in the estuary). In the Noosa Estuary, naturally occurring oyster aggregations
were only currently found where hard surfaces protrude from the soft sediment to a sufficient
height and orientation where fine sediments cannot accumulate, therefore allowing oysters
avoid being smothered and survive (i.e. aggregations on Rocky Point in Lake Weyba, along
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Weyba Creek and on artificial structures such as jetties outside the fish habitat area). Less
dense aggregations were also found in the main river channel near Tewantin (Figure 8).
We located one oyster bed comprised of dense leaf oysters (Isognomon ephippium) with
some rock oysters and a variety of sessile invertebrate species (this covers approximately
4020m2 of the substrate) (Figure 16). In addition, there were several intertidal and subtidal
rubble areas with sparse oyster aggregations, rocky reefs with oysters predominantly on
intertidal surfaces, oyster beds covered by sediment and extensive seagrass beds recorded
(Figure 8; Figure 16; Figure 17 & Figure 24). Mangroves and saltmarsh were also present
around the perimeter of the lower estuary, although these were not the focus of this
assessment so were not considered further. Based on available data for these habitat types,
mangroves occupy 1.7 km2 and saltmarsh occupies 0.1 km2 of the total 60.8 km2 habitat in
the Fish Habitat Area.
Noosa River - Tewantin Area
The reach referred to in this report as Tewantin area extends from site 1 upstream to site 5
downstream (Figure 8 & Figure 9). There are several large areas of shell and rocky rubble
that have been buried by up to 0.5 m of fine sediment around this area, particularly along
eroding edges (outside bends of the river) (Figure 8 & Figure 9). Oysters were recorded
aggregating in a narrow band in low densities on the rubble (based on visual assessment),
however dense aggregations were limited to intertidal areas (Figure 10) due to the presence
of a high coverage of macroalgae and fine algal turf that trapped a thick sediment layer,
smothering the surface (Figure 11) (a similar issue resulted in recruitment failure on upward
facing horizontal surfaces of settlement tiles in the estuary: ESP & TNC 2015). A low relief
layer of dead oyster shell covered the sediment surface over the rocky reef and intertidally
adjacent to the Tewantin boat ramp, indicating the presence of live oysters at some point,
although turbid conditions at the time of assessment prevented a more detailed assessment
of the density of live oysters found in those areas (Figure 12).
A large area of soft sediment had smothered oyster and rubble banks (shown in pink on
Figure 8) was discovered adjacent to Tewantin through direct observation and probing
(Figure 8a). The depth of sediment covering oyster shell in these areas was between 10 and
30 cm. These shallow oyster reefs and beds likely supported a large proportion of the
intertidal and shallow subtidal oysters, as is evidenced by their proximity to a substantial
indigenous midden site where oyster shell up to 4 m deep was discovered (Thurstan 2015).
The reefs likely covered most of the small bay near the current Council Chambers, although
this area is currently covered with sediment.
Probing of the soft sediment along the western bank of the river to the north of Tewantin
(around sites 2 and 3) found that there was a coarse shell grit or rubble bank approximately
30-50 cm below the current sediment surface. The extent of shell beds in this area requires a
more detailed assessment although none were found on the surface at these locations.
Burial is likely related to past mobilisation of sediment.
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Tewantin
Area
Noosa North
Shore Area
Weyba Creek
Area
Lake Weyba
Figure 7 Location of sites where water quality was assessed (source map Google Earth 2016)
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a) dead oysters on rock smotherd by sediment
d) coffee rock reef
Tewantin
Area
Historical rubble & oyster
beds likely to occur here
but currently buried by fine
sediment
Noosa North
Shore Area
b) oysters on rubble bank adjacent to
council chambers
c) dead oyster shell on rubble bank adjacent to
council chambers
Figure 8 Location of rock oyster aggregations, rubble and rock banks, rubble/oyster beds smothered by sediment and seagrass in the Noosa River and ten proposed
restoration sites in the Tewantin area (Sites 1 to 5) and Noosa North Shore area (Sites 8-10)(source map Google Earth 2016)
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Figure 9 Location of rock oyster aggregations, rubble and rock banks, rubble/oyster beds smothered by sediment and seagrass in the Noosa River at Tewantin (source map
Google Earth 2016)
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Figure 10 Oysters growing in a narrow band on rock rubble adjacent to council chambers
Figure 11 Oyster shell surrounding rocky rubble covered with dense macroalgae (Padina sp.)
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Figure 12 Coarse oyster shell grit on sandy beach adjacent to Tewantin boat ramp.
Figure 13 Sparse oyster shell surrounding rocky rubble covered by fine sediment along the main
channel of Noosa River adjacent to Hilton Parade.
Figure 14 Intertidal oysters and dead shell on rocky rubble along the main channel of Noosa
River adjacent to Cayman Quays just downstream of the Noosa Fish Market.
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Noosa River – North Shore
The area referred to as North Shore in this report includes site 6 to 10 (Figure 8). No oyster
beds or reefs were observed adjacent to or beneath the sediment surface at sites 8, 9 or 10
(Figure 8). There was at least 2 m of sandy sediment below these sites, although this is to be
expected as sediments are highly mobile in this area (where the hydrology has been
modified) and oyster beds may have been dredged in the past. There were several oysters
growing in a narrow band on a metal sign post (next to site 10; Figure 15) and some oysters
on mangrove roots at site 9. These sites are within the optimal growing area
(accommodation space) of oysters and occur within a historical oyster lease area, so there is
a high probability that oyster beds occurred at this sites but that the substrate was removed.
Sites 6 & 7 were adjacent to seagrass beds and we found hard substrate approximately
1.5 m below the sediment surface. There were no oyster beds located in close proximity to
these sites. The closest oyster aggregation was on an artificial rock wall adjacent to site 4.
Figure 15 Oysters growing on metal pole near site 10. The shore height oysters were growing
was limited to low intertidal and shallow subtidal (down shore of the adjacent
mangrove pneumatophores).
Weyba Creek
This area includes sites 11 to 15 in the main channel of Weyba Creek (Figure 16 & Figure
17). Two areas of shallow shell grit were recorded in the main channel of Weyba Creek
where tidal currents are strongest (Figure 17). While numerous dead oyster shells were
found on the sediment surface (Figure 17a-c), this habitat is in the process of being covered
by shifting sediment, with many of the remnant oyster shells also buried under the surface.
Small dead oyster shells were found approximately 30 cm below the sand surface at site 13
(Figure 18). The lack of vertical height above the sediment, suitable surface orientations
(lack of overhanging surfaces) and high mobility or accumulation of sand is likely to
contribute to the low numbers of live oysters currently growing in these areas (Figure 19).
Creating restoration structures with suitable variety of natural settlement surfaces
(particularly overhang surfaces), at a sufficient height on the shore (above LAT as this is
where most oysters grow), with sufficient vertical relief (i.e. >0.5m) and stabilisation of
sediment is essential to create conditions ideal for the natural recovery of oysters in this
habitat. It appears from this assessment that the only way to do this is to reintroduce
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aggregations of shell (a preferred settlement surface) at a suitable vertical height on the
shore (above LAT) and with sufficient vertical relief to mimic natural oyster reefs (i.e. >0.5 m).
The whole of Weyba Creek has conditions conducive to optimal growth of oysters in terms of
water temperature, salinity and depth (Table 3), however there are currently limited areas of
suitable structure particularly at an appropriate height above the sediment surface to allow
for oyster growth due to accumulation of fine sediment.
The negative impact of sedimentation on survival of oyster spat was highlighted in a recent
recruitment study (TNC & ESP 2015), which found that there was very limited recruitment to
the upper sides of settlement plates due to deposition of fine sediment and algae within just a
2 months of deployment. The current field assessment further highlighted the impact of the
accumulation of fine sediment on the available hard surfaces (Figure 19; Figure 20 & Figure
23). A plume of fine sediment on rocks was easily mobilised by creating a turbulent current
(sweeping hand motion) exposing dead oysters (Figure 20).
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Weyba Creek
b) dead leaf oysters on soft sediment
a) leaf oyster bed with low vertical relief on soft sediment
c) intertidal oyster aggregation in narrow band on rocks
Figure 16 Location of leaf oyster bed, rock oyster aggregations and seagrass in lower Weyba Creek (source map Google Earth 2016)
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a) dead oysters on rock among oyster shell
b) living and dead oysters on rock (oysters have died due to smothering from
sediment as indicated by greay area)
Weyba Creek
c) dead oyster and shell bed on soft sediment
Figure 17 Location of dead oyster shell beds along tidal channel and seagrass in Weyba Creek (source map Google Earth 2016)
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Figure 18 Small dead oyster shell buried 30cm below the sand surface at site 13.
Living rock oysters above
sand
Dead rock oysters below
sand
Figure 19 Small rock with live oysters and dead shell buried under the sand (any restoration will
require restoration units with a suitable height above the sediment surface).
Figure 20 Waving hand over rock surface easily mobilises the thick layer of fine silt covering
oysters on rocks along Weyba Creek, adjacent to leaf oyster bed.
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Figure 21 Narrow aggregation of oysters growing in intertidal zone on coffee rock along Weyba
Creek adjacent to leaf oyster bank.
Oysters were also recorded growing on several jetties and bridge pylons in a narrow
intertidal band; however, these artificial vertical surfaces do not replicate the same ecological
function or natural habitat complexity as natural oyster reefs and beds. Opportunities for
vertical growth of these oyster aggregations to form complex three-dimensional biogenic
structures are limited and oysters generally only form a thin veneer over the surface of
artificial structures.
Lake Weyba
The section includes sites 16 and 17 as shown in Figure 24 (note that restoration is not
planned at site 17 only water quality was taken at this site). Several natural oyster
aggregations were recorded on rocky outcrops in Lake Weyba (Figure 24), with the greatest
density of oysters aggregating in the narrow intertidal zone on the rocks (Figure 22 & Figure
24a,b). The aggregations formed on these rocks were typically only a single layer of oysters.
Salinity in Lake Weyba was measured as close to oceanic water (35.5 PSU) in October on
an outgoing tide, which is ideal for oyster growth; however, very fine sediment and dense
macroalgal growth on rocks appears to reducing the recruitment space available for oysters
(Figure 24d & Figure 23). Seagrass was recorded around the rocky areas in Lake Weyba
and was patchy throughout the Lake, although an extensive survey to assess the location
was not completed.
Sparse oyster aggregations were found on low relief rubble fields, although sedimentation
was an issue in these areas (Figure 24c & Figure 25).
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Figure 22 Dense aggregation of oysters growing in narrow intertidal band on exposed rocky reef
in Lake Weyba
bare rock below sand algae & fine above
sediment surface
Figure 23 Fine algae and sediment layer on rock pulled from sediment on southern edge of Lake
Weyba
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b) dense oysters on rock
a) Intertidal oysters on rock
Lake Weyba
c) rocky reef substrate
d) Intertidal oysters on rock
Figure 24 Location of oyster aggregations, rocky reefs and rubble banks in Lake Weyba (note: restoration is not planned at site 17 this was a site used for water quality
testing. There were also large areas of seagrass particularly around rubble banks recorded but not mapped. Source map: Google Earth 2016)
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Figure 25 Aggregation of oysters growing in narrow intertidal band on rock boulders near site 16
in Lake Weyba (yellow circles indicate oysters)
Historical vs Current Oyster Extent
A conservative estimate of the area occupied by oysters throughout the Noosa Estuary
based on the best available information is presented in Table 4. Conservative estimates
have been used throughout to ensure that the amount of oyster habitat restored would not
substitute habitat other important habitats within the Fish Habitat Area. Based on the
calculations below, the area proposed for the Resource Allocation Authority (RAA; 1440 m2)
represents a small proportion (<3.5%) of the area within the accommodation space likely to
have been harvested (assuming that oyster habitat naturally recovered to the area of the
RAA) and less than 17.5% of the maximum annual harvested area at the peak of the industry
(Table 4). Even if we add the large areas of degraded rubble and oyster aggregations (which
are not the same as oyster beds) to the proposed RAA area, it still occupies conservatively
11 to 54% of the area that should contain oyster habitat within the accommodation space.
Therefore, based on the conservative calculations below, we consider that the proposed
resource allocation application for the purposes of supporting natural restoration of a fish
habitat known to exist in the estuary should not be considered habitat substitution, rather
natural restoration of a small proportion of important estuarine habitat type that was removed
by early settlers of the area, in the same way as previous restoration of marine plants over
bare substrate has been completed in the Noosa River Estuary.
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Table 4 Calculation of oyster habitat area in the Noosa River Estuary
Oyster Area Calculation Areal Surface Area Assumptions/Exclusions
A) Area with the Area of Accommodation Area of oyster habitat within Given that estuaries in Florida also
potential to Space - Based on current historical harvest areas that have everglades and occurs at a
currently ambient water quality should occur in Noosa Estuary similar latitude to Noosa, the
contain oyster (temperature, salinity & depth) based on other similar system = assumption that oyster reefs may
2 2
habitat within in the lower section of the 41,530 m to 207,650 m have occupied 1-5% of the
the estuary, Lake Weyba and accommodation space is considered
accommodation Weyba Creek would have reasonable.
space and suitable conditions for oyster
historical oyster growth. Based on above, the The accommodation space and
lease areas accommodation space for the calculations includes areas within
entire lower Noosa Estuary and outside the FHA in the lower
2
(13,742,000 m ) minus area estuary
outside historical oyster lease Assumes oyster shell beds and rock
area (approximately / rubble areas are all suitable for
2
9,589,000 m ) = Area within recruitment (which based on current
historical oyster lease area assessment they are not)
(i.e. excluding Lake Weyba)
2
4,153,000m Assumes that oysters were not
dredged from Lake Weyba as we
If oyster reefs historically have no record of an oyster lease
represent between 1 and 5% there.
of the accommodation space
of an estuary, as found in Based on two-dimensional surface
Florida, then oyster beds and area of the estuary. Actual three-
reefs in the Noosa estuary dimensional calculation of area of
within the historical oyster the channel surface would be
lease area (1 to 5% x greater than this although all
2
4,153,000m ) calculations based on two
dimensional areas so would be
proportional.
B) Peak annual The number of live oysters Conservative estimate of the Estimated size of live oysters
harvest area exported from Noosa River in surface area required to meet harvested (to derive number per
from Noosa any year ranged from 2 to 6 live harvest records for a single bag)
River based on million individuals, multiplied year at the peak harvest =
fisheries by the maximum density of
2 -1
8,241m .yr assuming highest Unknown quantity of dead shell
records oysters known from restored density (the surface area harvested from the system (likely to
reefs elsewhere in the world of harvested annually for live be several times this surface area
-2
728 ± 102 ind. m (Casas et oysters would range from given that dead shell extends below
al. 2015)
2
2,409m and to 9,585 m .yr
2 -1 sediment surface)
depending on live oyster density Unknown density of oyster
Calculation of the area to meet in the estuary which is unknown)
a single harvest year = beds/reefs in the Noosa Estuary due
maximum density x maximum This is the area required meet a to historical extraction of dead shell
-2
harvest = 728 ind. m x 6 single annual harvest. Total area from soft sediment areas, therefore
million live oysters harvested that once had live oysters would maximum density known has been
be greater than this due to the used.
length of time required to Likely that harvest occurred across
regenerate reefs between multiple areas due to the need for
harvests, i.e. the same habitat oysters to regenerate. Based on
area cannot be harvested in modern cultivation techniques, it
successive years takes 2-3 years for oysters to reach
harvestable size.
Dredged oysters (which contributed
to the historically recorded harvest)
were likely much less dense than
those collected by hand from
intertidal and shallow beds based on
historical account (Smith 1981).
C) Current Surface area of all dead oyster Minimum area of dead oyster Due to the extensive presence of
extent of dead habitat identified in field habitat identified consisting of bare sediment throughout the
2
or buried Oyster assessments, based on visual buried oyster bank – 9,679 m estuary, we were not able to
beds/rubble inspection, sediment probing and functionally dead shell beds surveyed extensively for oyster shell
2 2
habitat and handheld GPS location. – 7,171 m = 16,850m or rubble due to survey time
measured in constraints, so the current extent is
Noosa River the minimum known. Oyster shell
within Historical buried under sediment near
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Oyster Area Calculation Areal Surface Area Assumptions/Exclusions
Oyster Leases Tewantin are likely to be greater
given the area possibly occupied in
the lower estuary based on 5% of
the accommodation space within
historical oyster leases and proximity
to an indigenous shellfish midden
with 4 m deep oyster shells.
Several constraints on placement of
restoration structures due to various
external factors are outlined in the
Oyster Restoration Management
Plan
D) Current Surface area of all living oyster Current area of living leaf oyster Oyster beds and reefs typically form
2
extent of habitat identified in field bed = 4,050 m on soft substrates due to an
degraded living assessments, based on visual accumulation of shell. These dense
Oyster inspection, sediment probing Current area of degraded oyster aggregations can form substantial
beds/rubble/agg and handheld GPS location. habitat assessed within historical reefs >0.5m above the sediment
regation habitat harvest areas (note this is not surface. Fundamentally, with the
measured in The locations surveyed are equivalent to Oyster beds or exception of the leaf oyster bed,
Noosa River shown in appendix A and all reefs as oysters only occur at oyster aggregations growing on
within Historical but sites 16 and 17 are within low densities – Beck et al. 2009) rocks are different habitat to oyster
Oyster Leases the historical oyster lease (includes: Rock/Rubble bank – beds/reefs that grow on soft
2
areas. 15,892 m ; Coffee rock reef – sediments.
2 2
705 m ) = 16,597 m
Due to the nature of equipment
Total living oyster habitat (Figure 5), dredging would have
2 2
(4,050 m + 16,597 m ) = occurred over soft sediment areas
2
20,647 m rather than rock/rubble so may have
re-suspended sediments transported
by floods, creating a negative
feedback loop and affecting oyster
bed recovery/ oyster recruitment
(although it is not possible to
determine).
Natural rock surfaces are not
currently suitable for recruitment of
dense oyster aggregations or the
formation of dense beds/reefs due to
a lack of oyster settlement on
horizontal surfaces (due to algae
and fine sediment) (TNC & ESP
2015), low surface area:volume ratio
of rubble banks; lack of small spaces
within the rubble; and, modern
requirement of oysters to grow in a
narrow intertidal zone to escape
degraded conditions.
Does not include aggregations of
oysters on jetties or seawalls which
are functionally not equivalent to
natural oyster beds/reefs. Oyster
aggregations growing in a thin
veneer on vertical surfaces are
limited in the extent they can grow
away from the vertical surface due to
gravity and adhesion tension. This
limits the potential to become three-
dimensional habitats. Further they
are often found outside the fish
habitat area and do not currently
form part of the complex natural
estuarine habitat mosaic (refer to
living foreshore concept that may
make this possible).
E) Current Surface area of all identified Current areas of bedrock with Only a narrow intertidal band on
extent of oyster buried oyster bank and rubble intertidal oyster aggregations in hard rock surfaces is occupied by
aggregations on + bedrock in field assessments Lake Weyba (not equivalent to sparse oyster aggregations. This
bedrock/rubble Oyster beds of reefs – Beck et area represents all bedrock/rubble
measured in al. 2009) (includes: rock rubble so would have a considerable area
Lake Weyba banks with sparse oyster
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Oyster Area Calculation Areal Surface Area Assumptions/Exclusions
2
(i.e. outside aggregation – 10,999 m ; of bare rock.
historical oyster Bedrock/Rock with oyster
2
lease area) aggregation – 3,805m ) =
2
14,804 m
F) Proposed Proposed area for Resource Surface area of the RAA = Assumes that oysters will recover
2
Restoration Allocation Authority is the 1440 m naturally to cover the full area of the
Area and maximum predicted extent that RAA.
Resource restored oyster beds would
Allocation Area reach given best estimates of Actual proposed direct development
(RAA) biomass accumulation. This footprint for restoration units is
2
allows for suitable buffers to <200m
surrounding habitat.
Restoration footprint per site
2 2
(12m ) x 16 sites = 192 m
2
RAA = 90 m x 16 sites
Proportion of A) There is currently The percentage of likely area Assumes that oysters grow naturally
2
estimated 4,153,000 m of occupied by oyster habitat within to cover the full area of the RAA.
historical and accommodation space within the accommodation space
current oyster the historical oyster leases. historically harvested, relative to
habitat relative Conservatively, if oyster RAA area requested (F/A x 100)
to proposed habitat historically covered = 0.7% - 3.5%
Resource between 1 to 5% of the
Allocation accommodation space of The percentage of estimated
Authority Noosa estuary = 41,530 m to
2 annual historical live oyster
(RAA) area 207,650 m
2 harvest area relative RAA area
requested (F/B x 100) = 17.5%
B) Annual historical live oyster
harvest area – the estimated The proportion of dead or buried
area of live oysters required to oyster habitat recorded from the
meet peak live harvest = estuary relative to the RAA area
2
8,241 m .yr
-1 requested (F/C x100) = 8%
C) Current extent of buried or Total area of degraded living
dead Oyster beds/rubble oyster and rubble habitat + RAA
measured in Noosa River relative to the likely area of
within historical oyster leases accommodation space occupied
= 16,850 m
2 by oyster habitat in similar
estuaries ((D+F)/A x 100) =
D) Current extent of degraded 10.6% to 53.2%
living Oyster
beds/rubble/aggregation = Based on these conservative
2
20,647 m (a potential benefit estimates, the proposed RAA
of natural restoration of oyster area will not exceed the
beds through the proposed estimated size of oyster
project is that it may support habitat that existed
regeneration of these areas) historically in the estuary
(even with existing degraded
live oyster habitat included)
and will not results in habitat
substitution. Note that natural
oyster habitats particularly
beds and reefs are not
functionally or ecologically
equivalent to oyster
aggregations on hard
engineered surface and
should not be considered as
such.
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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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Site Recommendation Reason
habitat site)
Seagrass observed in close proximity to proposed
development footprint
Site 7 Keep as per plan – bare sandy mud bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Pre-construction seagrass survey required
Seagrass observed in close proximity to proposed
Monitor sediment accumulation development footprint
Site 8 Keep as per plan – sandy bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Oyster shell habitat likely dredged from this area
Site 9 Keep as per plan – sandy bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Oyster shell habitat likely dredged from this area
Site 10 Keep as per plan – sandy bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Oyster shell habitat likely dredged from this area
Site 11 Keep as per plan – sandy bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Oyster shell habitat may have been dredged from this
area
Site 12 Keep as per plan – sandy bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Pre-construction seagrass survey required
Oyster shell habitat may have been dredged from this
area
Seagrass observed in close proximity to proposed
development footprint
Site 13 Keep as per plan – sandy bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Pre-construction seagrass survey required
Oyster shell currently buried at site (historical oyster
habitat site)
Seagrass observed in close proximity to proposed
development footprint
Site 14 Keep as per plan – sandy bottom Optimal zone for oyster growth, within historical oyster
harvesting area
Pre-construction seagrass survey required
Oyster shell currently buried at site (historical oyster
Monitor sediment accumulation habitat site)
Seagrass observed in close proximity to proposed
development footprint
Site 15 Remove or relocate to a new site upstream away from Optimal zone for oyster growth, within historical oyster
seagrass harvesting area. However, reef placement is over
recovered Halophila seagrass bed.
Site 16 Keep as per plan – fine sand/silt bottom Fine sediment easily re-suspended by wave action.
Pre-construction seagrass survey required Hard rock rubble below sediment surface
Monitor sediment accumulation Seagrass observed in close proximity to proposed
development footprint
We would recommend applying a development condition specifying that restoration units are
only placed on bare sand or mud substrate and not over existing mangrove propagules or
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seagrass (which is present in close proximity or at sites 2, 3, 6, 7 & 12). As such, additional
management controls may be required including independent pre-installation investigations
to verify the absence of seagrass and other marine plants and a buffer of at least 10 m from
the edge of the restoration area. This should be included as a fisheries condition of
approval.
We trust that this will provide satisfactory additional information in support of Council’s
application; however, if Council or Fisheries require video and additional information
collected in the field, please don’t hesitate to contact me on 0428 118 496 of by email
[email protected],
Simon Walker | BSc (Hons I) | PhD
Principal Ecologist | Ecological Service Professionals Pty Ltd
References:
Baggett LP, Powers SP, Brumbaugh R, Coen LD, DeAngelis B, Greene J, Hancock B, and Morlock S,
2014. Oyster habitat restoration monitoring and assessment handbook. The Nature
Conservancy, Arlington, VA, USA, 96pp. Available at http://www.oyster-restoration.org/wp-
content/uploads/2014/01/Oyster-Habitat-Restoration-Monitoring-and-Assessment-Handbook.pdf
Beck MW, Brumbaugh RD, Airoldi L, Carranza A, Coen LD, Crawford C, Defeo O, Edgar GJ, Hancock
B, Kay MC, Lenihan HS, Luckenback MW, Toropova CL, and Zhang G. 2009. Shellfish Reefs at
Risk: A Global Analysis of Problems and Solutions. The Nature Conservancy, Arlington VA.
Beck MW, Brumbaugh RD, Airoldi L, Carranza A, Coen LD, Crawford C, Defeo O, Edgar GJ, Hancock
B, Kay MC, Lenihan HS, Luckenbach MW, Toropova CL, Zhang G, & Guo X. 2011. Oyster reefs
at risk and recommendations for conservation, restoration, and management. Bioscience 61:
107–116. doi:10.1525/BIO.2011.61.2.5
Brumbaugh RD, Beck MW, Coen LD, Craig L. & Hicks P. 2006. A practitioners Guide to the Design
and Monitoring of Shellfish Restoration Projects: An Ecosystem Services Approach. The
Nature Conservancy, Arlington, Virginia.
Casas SM, La Peyre J, La Peyre MK. 2015. Restoration of oyster reefs in an estuarine lake:
population dynamics and shell accretion. Marine Ecology Progress Series 524: 171-184.
Cohen LD, Luckenback MW. 2004. Restoration Monitoring of Oyster Reefs. Report for the Oyster
Restoration Workgroup. Available at http://www.oyster-restoration.org/how-to-monitor-sites-
using-oyster-restoration-metrics/ Accessed on 14 October 2016.
DAF 2009. Rock Oysters Information Sheet.
https://www.daf.qld.gov.au/fisheries/aquaculture/aquaculture-species/rock-oysters Accessed 14
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Appendix A – Proposed Restoration Site Photos &
Sediment Characteristics
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Site 1 Site 2
patchy seagrass
Site 3 Site 4
patchy seagrass
Site 5 Site 6
Site 7 Site 8
patchy seagrass
Page 36
Site 9 Site 10
Site 11 Site 12
dense seagrass
Site 13 Site 14
Site 15 Site 16
Dense seagrass patches
separated by sparse seagrass
Page 37
Table A1 Site location (GDA94 Zone 56J) and sediment characteristics
Site Easting Northing Sediment Depth of hard
Type substrate
beneath soft
sediment (m)
1 504268 7082455 silt >1.5
2 504555 7081863 silt 0.3-0.5
3 504293 7081482 silt/sand 0.1-0.3
4 504441 7080714 sand/silt >1.5
5 504960 7080594 sand >1
6 505112 7080859 sand/silt 0.8
7 505433 7080679 sand/silt 0.8
8 506151 7080584 sand >1.5
9 507055 7081187 sand >1.5
10 507134 7081732 sand >1.5
11 508037 7080212 fine sand >1.5
12 507660 7079935 sand >1.5
13 507103 7078796 sand 0.3
14 507105 7078683 sand 0.3
15 507283 7078633 sand/silt not assessed
seagrass
present
16 506176 7075586 silt/fine sand 0.1
17 506399 7073871 sand/silt 0.1
[OCR of page images]
Table A1 Site location (GDA94 Zone 56J) and sediment characteristics
Easting Northing Y-VolTuteVals Depth of hard
Type substrate
beneath soft
sediment (m)
4 504268 7082455 silt >1.5
2 504555 7081863 silt 0.3-0.5
3 504293 7081482 silt/sand 0.1-0.3
4 504441 7080714 sand/silt >1.5
5 504960 7080594 sand >1
6 505112 7080859 sand/silt 0.8
7 505433 7080679 sand/silt 0.8
8 506151 7080584 sand >1.5
9 507055 7081187 sand >1.5
10 507134 7081732 sand >1.5
11 508037 7080212 fine sand >1.5
12 507660 7079935 sand >1.5
13 507103 7078796 sand 0.3
14 507105 7078683 sand 0.3
15 507283 7078633 sand/silt not assessed
seagrass
present
16 506176 7075586 silt/fine sand 0.1
17 506399 7073871 sand/silt 0.1
Page 38
Figure A1. GPS track logs and 85 points assessed during field assessment [OCR of page images] Noosa Habitat Assessment : Legend Tracklogs and points assessed # Feature 1 3 ’ 2» Feature 2 & tan (0,7 thle mA Nee) G50 Ls) Shee v7 Pree ty To) 313 Figure A1. GPS track logs and 85 points assessed during field assessment