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Appendix 3- Noosa restoration assessment report- Including Expert Elicitation Minutes
Attached to the e-mail Enclosure 5-Restoration Plan.eml, inside Operational Works Application OPW17/0016.
Report to The Thomas Foundation and Noosa Parks
Association on assessment of aquatic restoration and
management options for Noosa Estuary and Lakes
January 9, 2015
1
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Aims of the assessment
The Nature Conservancy (TNC), with support from The Thomas Foundation (TTF) and the
Noosa Parks Association (NPA) undertook an evaluation of options for restoration and
natural resource management of the Noosa River and Lakes system, and Laguna Bay
(hereafter referred to as Noosa Estuary).
The purpose of this assessment is to allow TTF, NPA, Noosa Shire Council, and TNC to:
i) Consider options for the future restoration and natural resource management of the
Noosa Estuary;
ii) Identify further research needs to support informed decisions about these options.
This report
Outlines the findings of the assessment.
Describes the assessment approach.
Provides an initial recommendation on restoration priorities.
Proposes key next steps and science needs.
This report is complementary to a presentation by The Nature Conservancy (Dr Eddie
Game) and The Thomas Foundation (Rowland Hill) to the Noosa Shire Council on
November 14, 2014.
Recommendations in brief
The restoration option considered likely to deliver the greatest improvement in the aquatic
biodiversity and fish abundance of Noosa Estuary is recreation of oyster reef habitat. We
considered restoration options as distinct from options that involved the management of
activities within Noosa Estuary, a number of which are described in the report.
Many oyster species naturally form reef structures where large numbers of oysters are
growing on top of the shells of older oysters, forming a consolidated reef (Figure 1). Where
they exist, oyster (and other shellfish) reefs provide critical nursery and feeding grounds for
fish and crab populations, increasing the biodiversity and abundance of aquatic resources in
the surrounding waters1. They also consolidate sediment, improve water quality, and can
increase the productivity of other nearby habitats such as seagrass and mangroves2.
We anticipate that oyster reef restoration would focus on Saccostrea glomerata (Sydney
rock oyster, see Figure 2) as this is the most abundant native oyster in Noosa Estuary. There
is also the possibility that reefs could be developed using may be multi-species including
others that are found in Noosa Estuary such as Isognomon ephippium (Rounded Tooth pearl
oyster, see Figure 3). The reconstruction of Saccostrea glomerata reefs has not to our
knowledge been done before so any attempt to do this in Noosa Estuary would be
somewhat experimental but also of international significance.
1
Peterson CH, Grabowski JH, Powers SP. 2003. Estimated enhancement of fish production resulting from restoring oyster reef habitat:
Quantitative valuation. Marine Ecology Progress Series 264: 249–264.
2
Grabowski, J.H., et al., 2012. Economic valuation of ecosystem services provided by oyster reefs. Bioscience 62(10): p. 900-909.
2
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Figure 1 Reconstructed oyster reef in Mobile Bay, Alabama.
The principal reasons why oyster reefs were considered by the team of experts to be the
priority habitat restoration activity are that Noosa Estuary has extensive mangrove habitat,
and a reasonable amount of seagrass habitat, such that investment in increasing the area of
these habitats is likely to be subject to diminishing returns. In contrast, reefs formed from
oysters appear likely to have been a historical component of Noosa Estuary3 but are now
almost entirely missing. As such, restoring oyster reef habitat is likely to make an important
contribution to restoring the ecology of Noosa Estuary. Additionally, oysters still exist in
Noosa Estuary and appear on most hard structures (e.g., wharf pylons, see Figure 2) and in
some places on the substrate (e.g., Weyba Creek), suggesting that water quality is unlikely
to be a limiting factor in the development of oyster reefs and that reef restoration has a
reasonable chance of success.
In order to more thoroughly evaluate the potential for oyster reef restoration in Noosa
Estuary, it would be a priority to investigate current rates and distribution of oyster
recruitment within the estuary.
These recommendations are not an indication of TNC’s commitment to further work in the
Noosa Estuary.
3
Beck, M., D. R. Brumbaugh, L. Airoldi, A. Carranza, L. D. Coen, C. Crawford, O. Defeo, G. J. Edgar, B. Hancock, M. C. Kay, H. S. Lenihan, M.
W. Luckenback, C. L. Toropova, G. Zhang, and X. Guo. 2011. Oyster reefs at risk and recommendations for conservation, restoration, and
management. Bioscience 61:107-116.
3
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Figure 2 Sydney rock oysters (Saccostrea glomerata) on a concrete wall in Noosa Sound.
Figure 3 Rounded Tooth pearl oyster (Isognomon ephippium) from Weyba Creek, Noosa.
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Assessment approach
To provide a rapid and efficient assessment of restoration and management options for
Noosa Estuary, TNC used an expert driven approach. The assessment was centred around a
two day workshop (October 30 & 31, 2014) facilitated by TNC Senior Scientist Dr Eddie
Game and based on the process of Structured Decision Making. Structured Decision Making
is a process that emphasizes the rapid and effective generation and evaluation of options,
while trying to minimize the numerous psychological traps and biases that commonly
present in assessments based on expert judgement4. Ten expert participants were chosen
based on their substantive knowledge of topics related to the ecology of Noosa Estuary, the
management and restoration of estuary habitats, and the ability to apply this knowledge to
the case of Noosa Estuary. The full list and bios of experts who participated in the workshop
is provided in Appendix 1. A number of additional experts were also consulted prior to the
workshop as part of preparing the background material contained in Appendix 2. These
additional experts are also identified at the bottom of Appendix 1.
Restoration and management objectives and indicators
Identifying a set of restoration and management options depends on having clear objectives
that the options are desired to work towards. The objective provided to the experts at the
workshop were:
1. To increase fish abundance in Noosa Estuary.
2. To increase aquatic biodiversity in Noosa Estuary.
3. To ensure the estuary's biodiversity and ecological health match that of the
terrestrial biosphere
When using multiple experts to evaluate the consequence that any restoration or
management option is likely to have for these objectives, it is essential that all experts are
judging the same thing. In the case of objective #1 above for example, one expert might be
evaluating the consequence of mangrove restoration for bream whereas another might be
thinking of whiting; this will lead them to evaluate the consequence differently. This
problem is known in expert elicitation as underspecification. To address this issue, the
experts were asked to come up with a set of indicators that would reflect the intention of
the objectives, and for which consequences would be evaluated separately. A large number
of possible indicators were considered with those selected being considered representative
of different aspects of Noosa’s aquatic biodiversity and ecology, and the range of ways that
the people interact with this biodiversity. Table 1 provides the list of chosen indicators along
with the rationale behind their selection.
4
Gregory, R., L. Failing, M. Harstone, G. Long, T. McDaniels, and D. Ohlson. 2012. Structured Decision Making: A Practical Guide to
Environmental Management Choices. Wiley-Blackwell, Oxford, UK.
5
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Table 2 List of indicators used for the evaluation of restoration and management options in
Noosa Estuary along with the rationale for their selection.
Indicator Rationale
School prawn (Metapenaeus School prawns are a critical part of the Noosa Estuary ecosystem.
macleayi) abundance Their entire lifecycle occurs within the estuary and as detritivores
they play a crucial role in converting detritus (mainly organic material
in lake sediments) into useful energy for a wide range of estuary
species. School prawns are a key food source for many fish species
and probably one of the key drivers of fish productivity in the Noosa
system. They can be both commercially and recreationally harvested.
Bream (Acanthopagrus sp.) Bream represent one of the principal recreational fishing species in
abundance the Noosa Estuary, and are also characteristic of a range of fish
species that utilize structured habitats within the estuary, like fallen
logs, reefs, and mangroves.
Whiting (Sillago sp.) Whiting are an important recreational fish species but are also
abundance important for the visual perception of fish abundance in the estuary
as they are the species visitors will see most commonly close to
shore. Whiting are also characteristic of fish that predominately
utilize sandy and soft bottom habitats.
Mullet (Mugil cephalus) Mullet are an important commercial and recreational fish species in
abundance Noosa Estuary. Like school prawns, mullet are detritivores so play the
same important role in nutrient cycling in the estuary, and also
between the estuary and nearby surf zone. Mullet availability within
the estuary is likely to be a major driver for the abundance of other
large fish species.
Bird (various species) The abundance of bird species that use the estuary in different ways
abundance (such are raptors and wading birds) can be a good indicator of the
availability of good quality habitat and a healthy, productive
ecosystem. They are also one of the most visible estuary fauna and
valued highly be visitors.
Yabby (Trypaea Marine yabbies are an important part of sand and mudflat
australiensis) abundance ecosystems. They are also an important bait source for recreational
fishing.
Crab (various species) Crabs of various species occupy all the aquatic habitats of Noosa
abundance Estuary. Some, like mud crabs, are important recreational species,
but all crabs represent an important ecosystem component as a key
food source for many fish species.
Aquatic species diversity The overall diversity of species in the estuary is a good indication of
ecosystem health and the diversity of healthy habitats.
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Restoration and management options
One of the main purposes of the expert workshop was to identify the range of potential
restoration and/or management options that could be considered in an effort to achieve the
objectives outlined above. Evaluating a diverse set of alternative options is at the heart of
good science-based decision making. To this end, the expert participants were asked to
think broadly and freely about restoration and management options, and were explicitly
instructed not to consider the socio-political feasibility or desirability of the options. This
was done to limit the risk that experts would prematurely discard potential options because
of perceived socio-political feasibility issues. Although societal values must be a critical part
of any decision about restoration and management of Noosa Estuary, we did not believe
that this group of experts were the right people to consider such values, especially in the
absence of community consultation. Instead, the experts were asked only to consider the
technical feasibility of proposed options. It is important, therefore, to be clear that these
options do not constitute recommendations, only the set of possible options that were
identified and evaluated in the workshop.
A total of 14 options were identified (see Table 2). Broadly, these include 7 restoration
options and 7 options that focus on management of existing activities within Noosa Estuary.
These options are moderately specific, which was necessary so that experts were conceiving
of the same thing during their subsequent evaluations. This, however, means that there are
likely multiple ways to execute each of these options. The 14 options span a wide range of
habitats and activities, and while not exhaustive, is likely to represent most of the spectrum
as far as types of aquatic restoration and management that could occur in Noosa.
Table 2 Restoration and management options identified during the expert workshop.
Option Key actions
Restoration options
Restoration of seagrass Restore seagrass habitat through improved control and redesign (e.g.,
swing moorings) of boat moorings
Oyster reef restoration Create oyster reefs initially in Weyba Creek and Lake Weyba
Living shorelines Replace hardened shoreline protection with structures that incorporate
mangroves and oyster reefs
Improve biological connectivity and extent of habitat mosaic between
Noosa and Tewantin
Provide habitat/hard Sub-tidal reef structures in the main channel between Noosa and Tewantin
substrate stepping Improve biological connectivity through increase hard substrate and
stones habitat mosaics
Prawn restocking Restocking of prawns into the lakes and river
Restoration of Kin Kin Assess current inputs and status of catchment
catchment Improved land management practices
Habitat provision for Improve habitat availability for iconic species raptor species by
Raptors supplemental feeding
Local education campaign and initiative
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Management options
North Shore Create a “Restoration Zone” to restrict access
management/vehicle Provide a buffer between recreational and commercial activities
closure Ensure that any conservation zone includes both terrestrial dunes, beach
and near-shore areas
Wake management Manage boat speed and wake
“between the lakes” Improve commercial boat design
Estuary zoning Reduce the recreational catch
(emphasis on rec. Increase catch and release programs including training / education
fishing) Provide support for improved fish habitat
Permitting
Cessation of Closure of fishing areas particularly between the lakes
commercial prawn Buyback of fishing licences
trawling Modified fishing practices
Decreased or limited catch (size or timing)
Better management of Limit catch on Noosa North Shore
commercial mullet Provide pathways to increase product value
fishery Modify fishing practices - education
Transform gill-net Transform gill net industry to high value line caught industry
fishery to higher value
fishery
Stormwater Improve the quality of water runoff flowing into the estuary through
management wetlands and other design features such as flow restrictors and pollution
traps
Expert evaluation of options
Following the identification of the options presented above, the experts were asked to
provide their judgment on the likely consequence of these options for the indicators
identified earlier. Initially judgement was sought on whether undertaking the activities
associated with an option would lead directly to an increase (or possibly a decrease) in the
abundance of each indicator group, and then subsequently the relative magnitude of the
likely increase. These assessments are presented in Table 3.
In addition to assessing the consequence of options for the ecological indicators, the experts
were asked to identify other benefits likely to be associated with undertaking each option.
For each option, the expert group also identified some key uncertainties associated with the
option. These uncertainties can help flag priority science tasks needed in order to more
thoroughly evaluate that option. Where possible, the experts were asked for indicative costs
of the options. In most cases these costs were highly uncertain because there were different
ways that each option could be executed and financed. Finally, for each option the experts
were asked to conduct a pre-mortem. This is a risk identification exercise where each person
was asked to imagine that the option had been undertaken and it was now 5 years into the
future and something had gone very wrong with the project. Each person is then asked to
describe what they imagined went wrong with the project. This has proved an effective way
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to elicit risk information5. These additional pieces of assessment are also presented in Table
3.
Evaluation results
Based on the judgement of the experts involved in the workshop, the two options likely to
have the largest positive impact on the suite of indicators species are, oyster reef
restoration, and cessation of commercial prawn trawling (Table 3). Compared with the other
restoration activities considered, the recreation of oyster reefs within Noosa Estuary was
predicted to ultimately lead to relatively larger increases in important, structure using
recreational fish species (represent by bream in the indicator list), crab populations, and the
overall biodiversity of the estuary. The principal reasons why oyster reefs were considered
likely to have relatively larger impact than restoration of other habitats such as mangroves
and seagrass, is that that Noosa Estuary has retained a large amount of intact mangrove
habitat (Figure 4) such that it is unlikely to be a limiting feature in the system. Therefore
restoring additional mangrove habitat, while positive, is likely to only have a small impact on
the objectives considered here. Similarly for seagrass; there is a reasonable amount of
seagrass remaining in Noosa Estuary, and only a small number of places where additional
restoration would likely be successful.
Figure 4 Healthy mangrove habitat, Lake Cootharaba, Noosa.
5
Game, E. T., J. A. Fitzsimons, G. Lipsett-Moore, and E. McDonald-Madden. 2013. Subjective risk assessment for planning conservation
projects. Environmental Research Letters 8:045027.
9
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10
Table 3 Expert evaluation of restoration and management options for Noosa Estuary. The predicted consequence for a range of indictors is illustrated with arrows. The direction of the arrow indicates
either a predicted increase or decrease, and the relative size of the arrow provides a relative measure of the extent of the change likely as a result of each option (i.e., a larger arrow means a relatively
larger expected impact for that indicator). Also presented for each option are associated ancillary benefits, key uncertainties, an estimate of cost, and potential risks to success of the option.
Option Key actions Consequence for chosen indicators Other benefits Key uncertainties Cost Pre-mortem
estimate
Prawns Bream Whiting Mullet Birds Yabbies Crabs Biodiver
sity
Restoration Restore seagrass Increased fisheries Negative sentiment $5k per Community backlash and
of seagrass habitat through productivity from community who boat lack of support
improved control Increased availability want “clean” sandy mooring Vessels anchoring rather
and redesign (e.g.,
swing moorings) of
of habitat
Carbon
beaches rather than
seagrass
than using available
seagrass friendly
boat moorings *# sequestration moorings
Improved
management of
boat mooring areas
Oyster reef Create oyster reefs Improved water Possible disease $100K per No community support
restoration initially in Weyba quality transmission year or community backlash
Creek and Lake Sediment Natural recruitment initially for Increased oyster disease
Weyba stabilisation rates 5 year transmission
Citizen engagement
Increased fishing
Survival of oysters
Design of reefs
pilot then
ongoing
Increased E. coli
No impact on the
* aggregation Future magnitude of receiving environment
Enhancing existing water quality Loss of other habitats
mangrove and improvements
seagrass habitat
Living Replace hardened Increased public Engineering viability $1000+ Exacerbate erosion in
shorelines shoreline protection awareness and Public support through some areas
with structures that ownership shoreline stewardship Community backlash
incorporate Erosion protection Inability to manage
mangroves and
oyster reefs
Improved natural
aesthetics
marine plants due to
legislative implications
Improve biological * Atonement for past
connectivity and actions
extent of habitat
mosaic between
Noosa and Tewantin
Provide Sub-tidal reef Oysters recruiting Engineering $100k+ Navigation hazards
habitat/hard structures in the naturally and complexities / Fish attraction not
substrate
stepping
main channel
between Noosa and
associated benefits
Increased
modified
hydrodynamics
production
Invasion by exotic
stones Tewantin * recruitment of some Meta-population species
Improve biological fisheries species dynamics Suffocate action
connectivity Fish aggregation Size and spacing of Reduction in soft
– Positive effect on indicator species * shorebirds (e.g. migratory waders, oystercatchers etc.); # raptors; ^ seabirds; § consequence not able to be assessed due to a
– Negative effect on indicator species lack of specificity about the actions to be taken
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Option Key actions Consequence for chosen indicators Other benefits Key uncertainties Cost Pre-mortem
estimate
Prawns Bream Whiting Mullet Birds Yabbies Crabs Biodiver
sity
through increase habitat blocks sediment habitat
hard substrate and What substrate to use
habitat mosaics
Prawn Restocking of Improved water Unclear as to the Requires Displacement of existing
restocking prawns into the quality current status of the further species
lakes and river Improved benthic stocks and therefore if info Change in fishing
habitat quality and restocking would be practices / target species
sediment turnover
Increased
required
Current carrying
No measurable
improvement in fisheries
recreational fishing capacity of lakes and
benefits through DIY river
bait and target Displacement of rare
species species
Restoration Assess current Improved water Current condition of Initial No measurable
of Kin Kin inputs and status of quality the catchment $100k; up improvement in fisheries
catchment catchment Improved Extent of erosion / to
Improved land
§ § § § § § connectivity for fish accretion $1M+for
management § § species actions
practices “Insurance” for
other restoration
options
Habitat Improve habitat Visual indicator of Current carrying $100K Birds don’t use artificial
provision for availability for iconic restoration success capacity for raptors in roosts
Raptors species raptor Increased the estuary Not tangible benefit to
species by community Extent of roost use community
supplemental engagement Possible mortality from
feeding Community human interaction
Local education # monitoring program
campaign and Estuarine health
initiative indicator
Increased tourism
opportunities
North Shore Create a Increase in fish Size of impact $200K Community backlash
management “Restoration Zone” movement / energy Moving fishing No measurable
/vehicle to restrict access transfer between pressure elsewhere improvement in fisheries
closure Provide a buffer estuary and coast Poaching
between Possible increased
recreational and
commercial
* #^
larval fish supply /
food for other
activities species
Ensure that any Reduced fishing
conservation zone pressure
includes both
– Positive effect on indicator species * shorebirds (e.g. migratory waders, oystercatchers etc.); # raptors; ^ seabirds; § consequence not able to be assessed due to a
– Negative effect on indicator species lack of specificity about the actions to be taken
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Option Key actions Consequence for chosen indicators Other benefits Key uncertainties Cost Pre-mortem
estimate
Prawns Bream Whiting Mullet Birds Yabbies Crabs Biodiver
sity
terrestrial dunes,
beach and near-
shore areas
Wake Manage boat speed Increased aesthetic Implementation ability ? Lost investment due to
management and wake value How to achieve failure
“between Improve Improved safety for outcomes Loss of shoreline access
the lakes” commercial boat all users Policing and appreciation of the
design Shoreline estuary
stabilisation through
wake management
Increased pressure
elsewhere
*# Integrity of
ecotourism ventures
Improved water
filtration/quality
Estuary Reduce the Improved fishing Needs to be part of ? Community backlash
zoning recreational catch practice resulting in the package for No measurable
(emphasis on Increase catch and improved fish stocks improved commercial improvement in fisheries
rec. fishing) release programs fishing management
including training /
education
*
#^
Community response
Increased fishing
Provide support for pressure from
improved fish elsewhere
habitat
Permitting
Cessation of Closure of fishing Improved water Actual catch rates and Violence and backlash
commercial areas particularly quality current stock from fishing community
prawn between the lakes Improved benthic assessment No recovery of stocks
trawling Buyback of fishing habitat quality and Possibility for natural
licences sediment turnover recovery
Modified fishing Increased
practices recreational fishing
Decreased or
*# benefits through DIY
limited catch (size bait and target
or timing) species
Better Limit catch on Improved efficiency Area too limited in size ? Violence and backlash
management Noosa North Shore in commercial to have a measurable from fishing community
of
commercial
mullet
Provide pathways to
increase product
value #^
practices
Improved water
quality
impact on local stocks
Shifting fishing
pressure elsewhere -
No recovery of stocks
fishery Modify fishing
* Increased mullet all caught
practices - commercial value of further north
– Positive effect on indicator species * shorebirds (e.g. migratory waders, oystercatchers etc.); # raptors; ^ seabirds; § consequence not able to be assessed due to a
– Negative effect on indicator species lack of specificity about the actions to be taken
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Option Key actions Consequence for chosen indicators Other benefits Key uncertainties Cost Pre-mortem
estimate
Prawns Bream Whiting Mullet Birds Yabbies Crabs Biodiver
sity
education product Actual catch rates and
Increased habitat current stock
value and assessment
productivity
Reduction in habitat
destruction
Transform Transform gill net Improved efficiency Current fish stocks and ? Backlash from
gill-net industry to high in commercial impact of fishing commercial fishers
fishery to value line caught practices practice Inability to adopt new
higher value
fishery
industry
Improved water
quality
fishing practices
No improvement in fish
Increased stocks
commercial value of
product
Stormwater Improve the quality Enhance biogenic Magnitude of $500K+ No tangible benefit to
management of water runoff habitat quality and improvement possible water quality
flowing into the resilience due to given there is limited
estuary through reduced external future development
wetlands and other § § § § § § § § pressures
design features such Increased viability of
as flow restrictors restoration success
and pollution traps
– Positive effect on indicator species * shorebirds (e.g. migratory waders, oystercatchers etc.); # raptors; ^ seabirds; § consequence not able to be assessed due to a
– Negative effect on indicator species lack of specificity about the actions to be taken
Page 14
In contrast, Noosa Estuary has very little hard substrate such as biogenic reefs. Reefs formed
from oysters appear likely to have been a historical component of Noosa Estuary6,7,8 but are
now almost entirely missing. As such, restoring oyster reef habitat is likely to make an
important contribution to restoring the ecology of Noosa Estuary and particularly its
fisheries productivity. Other notable benefits of oyster reef restoration would likely include
improved water quality because of the filtration conducted by oysters 9, enhanced
productivity of existing mangroves and seagrass species as the connection between habitats
is important for many species, additional recreational fishing areas as many fish are likely to
be attracted to oyster reefs for feeding, and numerous citizen engagement opportunities in
their development and subsequent monitoring.
Oyster reef restoration would likely focus on Saccostrea glomerata (Sydney rock oyster, see
Figure 2) as this is the most abundant native oyster in Noosa Estuary. There is also the
possibility that reefs could be developed using may be multi-species including others that
are found in Noosa Estuary such as Isognomon ephippium (Rounded Tooth pearl oyster, see
Figure 3). Because the reconstruction of Saccostrea glomerata reefs has not previously been
undertaken, there are uncertainties around the design of the restored reefs (e.g., what
engineered structures to use), and the magnitude of the benefits that could be expected.
Similarly, although oysters are naturally present in the Noosa Estuary, it is uncertain
whether recruitment and survival of oysters is adequate to re-establish reefs without
hatchery raised spat. Another risk is that the establishment of large number of oysters in the
estuary could lead to increased incidence of oyster disease that may harm the existing
oyster populations in the estuary.
With regard to managing existing activities within Noosa Estuary, the option likely to deliver
the greatest benefit towards the objectives identified here was the cessation of commercial
prawn trawling. The principal reasons for this predicted impact are that the school prawns
targeted by the commercial fishery are a critical part of the Noosa Estuary aquatic
ecosystem (as identified in Table 1), and their current abundance is likely to be much
reduced from historical levels. Additionally, the use of beam-trawls to capture the prawns is
likely to do major damage to benthic habitats, such that cessation of trawling will deliver a
range of fisheries related benefits through both the increased abundance of prawns and the
increased integrity of benthic habitats in the estuary. Because any future management of
the prawn fishery is unlikely to involve either TTF or TNC, we have considered it further in
our recommendations.
For the options that involved restoration of the Kin Kin catchment and storm water
management, the experts involved did not feel able to evaluate the likely consequences
because the current level of impact each of these has on the Noosa Estuary aquatic
environment was not clearly known.
6
Beck, M., D. R. Brumbaugh, L. Airoldi, A. Carranza, L. D. Coen, C. Crawford, O. Defeo, G. J. Edgar, B. Hancock, M. C. Kay, H. S. Lenihan, M.
W. Luckenback, C. L. Toropova, G. Zhang, and X. Guo. 2011. Oyster reefs at risk and recommendations for conservation, restoration, and
management. Bioscience 61:107-11
7
Brown, E. R. 2000. Cooloola Coast: Noosa to Fraser Island: The Aboriginal and Settlers Histories of a Unique Environment. Univ. of
Queensland Press.
8
Lergessner, J. G. 2006. Oysterers of Moreton Bay. James Lergessner.
9
Zu Ermgassen, P. S., M. D. Spalding, R. E. Grizzle, and R. D. Brumbaugh. 2013. Quantifying the loss of a marine ecosystem service:
filtration by the eastern oyster in US estuaries. Estuaries and coasts 36:36-43.
14
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Rapid field assessment
In addition to the expert workshop, TNC undertook a rapid preliminary field assessment in
Noosa Estuary. The assessment was facilitated by the Noosa Parks Association. The purpose
of this assessment was to look at potential locations for habitat restoration activities, with
an emphasis on oyster reef restoration. The people involved in this field assessment were
Bryan DeAngelis (a coastal habitat restoration expert with TNC’s North America program),
Dr Simon Walker (a Brisbane based marine ecologist with many years’ experience working
on habitat restoration in South East Queensland estuaries), and Dr Eddie Game (marine
biologist and TNC’s lead scientist in the Asia-Pacific region).
Although there has been substantial modification of aquatic habitats in Noosa Estuary (e.g.,
the development of Hayes Island), the remaining contribution of mangrove, seagrass, and
unstructured benthic habitats (e.g., sandy bottom) is high. While the relative contributions
from each of these habitats to estuary productivity may be reduced because of external
stressors (e.g., sedimentation or pollution), there appears to be limited opportunity for
active restoration of those habitats. Regarding these mangrove and seagrass habitats,
effort would likely be better spent managing existing habitat for improved health and
resiliency, and thus ecosystem services, by reducing anthropogenic impacts.
The most noticeable lack of habitat was structured, biogenic habitat from reef-forming
bivalves. In this regard, Noosa contrasts to other nearby systems such as Pumicestone
Passage which has rather extensive intertidal shellfish reef habitat. Saccostrea glomerata
(Sydney rock oyster) was regularly observed in much of the southern portions of the
estuary, particularly in the slower moving, backwaters. Nearly all hard substrate showed
evidence of oyster settlement (Figure 5). From a restoration planning perspective, this is a
very positive sign. It hints at the possibility of potentially eliminating the need for hatchery-
derived oysters to increase reproductive output beyond recruitment-limiting
conditions. While settlement (and apparent recruitment) of oysters was observed in
multiple locations where hard substrate existed, in most instances it was restricted to the
intertidal zone (e.g., top and middle panel Figure 5). This effect may be the result of
predation pressure of oysters that are fully sub-tidal such that oysters are found in greatest
densities in a band near the upper limit of their exposure tolerance. Should this be the case,
it is unlikely to be a limiting factor to potential oyster reef restoration works in Noosa
Estuary because many of the candidate areas for oyster restoration are intertidal.
One small sub-tidal reef was observed, being comprised on the oyster species Isognomon
ephippium (Rounded Tooth pearl oyster, see Figure 6). This was found in a deep section of
Weyba Creek and although heavily impacted by sediment, it is suggestive of the possibility
that reconstructed oyster reef may ultimately be comprised of multiple species.
Based on our field assessment, the most promising candidate sites for pilot oyster reefs
restoration are likely to be sites in Weyba Creek and Lake Weyba.
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Figure 5 Examples of oyster settlement in Noosa Estuary. Top shows oysters on bridge
pylons, middle shows oyster on wooden jetty batons, and bottom shows a juvenile oyster
on the dead shell of another bivalve species.
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Figure 6 Section of oyster reef comprised of Isognomon ephippium (Rounded Tooth pearl
oyster) found in Weyba Creek.
Recommendations and future research needs
Based on the information gathered during this assessment, our recommendation is that to
increase fish abundance and aquatic biodiversity in Noosa Estuary, the priority restoration
actions would be to pilot the development of oyster reefs. This recommendation does
indicate a commitment by TNC to be involved in an oyster reef restoration project in Noosa
Estuary. In order to make a better informed judgment about the potential and design of
these reefs, some additional research is necessary. Most urgent amongst the additional
research tasks is an assessment of current oyster settlement and recruitment in Noosa
Estuary. This research would indicate whether there is enough oyster recruitment in Noosa
Estuary to reconstruct reefs without supplement from hatcheries, and also provide
important insights into the design and placement of pilot reefs.
Based on the key uncertainties identified by the experts for a range of restoration and
management options, it was also clear that an assessment of current fish and prawn stocks
in Noosa Estuary, and a model of their harvest would be invaluable in evaluating different
management options and the potential of Noosa Estuary to sustain a boutique sustainable
seafood industry.
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Acknowledgements
The Nature Conservancy would like to thank The Thomas Foundation and the Noosa Parks
Association for providing the funding for this assessment. We would also like to thank
specifically Michael Gloster and Bryan Walsh of the Noosa Parks Association for their
invaluable assistance and input at multiple points during this assessment, and Carl Beck for
kindly making his boat available for our field assessment. Thanks also to all the experts who
shared their knowledge with us during this assessment.
Supplemental files attached to this report
Appendix 1 – List of experts that participated workshop or consulted during this assessment
Appendix 2 – Background material on Noosa Estuary prepared for the expert workshop
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Appendix 1 Expert workshop participants Assoc. Prof. Greg Skilleter The University of Queensland Greg is currently a Reader in Marine Ecology at the University of Queensland. He is an internationally recognised expert on assessing the mechanistic links between coastal habitat mosaics and fisheries, including restoration of coastal habitats following natural and man- made impacts. Greg has previous relevant experience working in Noosa Estuary on the impacts of dredging and habitat creation on benthic communities (including fish and prawns). Greg’s research group currently focus on assessing the impacts of large-scale human influences such as climate change and nutrient enrichment on the coastal environment. Greg provides leading expertise on the interactions between fish, prawns and other benthic species and their coastal habitats, and a pragmatic approach to assessing ways to improve fisheries production in the Noosa Estuary into the future. Prof. Neil Loneragan Murdoch University Neil is currently a distinguished Professor of Marine Ecology and Conservation at Murdoch University in WA and Leader of the Environmental and Conservation Cluster. Prior to joining Murdoch, Neil spent 14 years working for the CSIRO in fisheries research throughout Queensland and SE Asia. He is internationally recognized for his work in evaluating the significance of coastal habitats for fisheries production and biodiversity, the spatial arrangements of habitats and their significance for fish and crustacean communities, and how restocking and stock enhancement can be used to rebuild marine systems. Neil has led numerous assessments of the value of coastal habitat for fisheries in Australia and SE Asia. In particular he was instrumental in assessing how the loss of seagrass due to a cyclone affects fisheries production in Exmouth, WA. Neil is a member of the International Steering Committee for the International Symposia for Stock Enhancement and Sea Ranching (www.searanching.org). He was also on the International Advisory Board for two interdisciplinary projects by the University of Wageningen (The Netherlands), which assessed the sustainability of particular fishing practices in SE Asia and the central Pacific.
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Assoc. Prof. Thomas Schlacher The University of the Sunshine Coast Thomas is an internationally recognised expert in coastal ecology, focussed particularly at the interface between estuaries and the ocean. Noosa and the Sunshine Coast is Thomas’ backyard, and he has built a considerable body of literature examining the impacts of humans on coastal ecosystems and how to best manage and restore these systems to improve condition. Of particular relevance to this project is his research on nuisance algal blooms and the impacts of coastal urbanisation on estuarine fisheries using accurate pollution indicators, nutrient flow and dynamics in coastal systems, and assessing the human impacts and restoration of sandy beaches. Dr Emma Jackson Central Queensland University Emma has over 15 years experience as a seagrass ecologist assessing the landscape ecology and effects of human pressures on the state of structural benthic habitats (particularly seagrass and biogenic reef) and the subsequent changes in ecosystem function and services. She is particularly interested in the structure and functioning of seagrass habitats at a landscape scale (fragmentation, depth squeeze, connectivity) and is currently engaged in the large-scale restoration of seagrass habitats in Port Curtis, including researching methods suitable for restoration in Eastern Australia. She bridges the knowledge gap between science and policy including assessing the conservation importance of coastal habitats, and identifying suitable indicators for monitoring change and targets for habitat restoration.
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Dr Melanie Bishop Macquarie University Melanie is a recognised expert in estuarine ecology including assessing natural and human-mediated processes that control coastal biodiversity and its important ecosystem functions. She uses manipulative field experiments to investigate effects of local and global changes, often producing results that could not have been predicted using theoretical or modelling approaches alone. She brings relevant skills in restoration of estuaries, particularly in identifying existing stressors in the system and working on relevant solutions to reduce or remove these prior to restoration activities. She is particularly interested in the use of bio-engineers (habitat transforming species, such as oysters) to restore degraded habitats. Recent research highlights include providing one of the first assessments of how positive interactions among species can maintain biodiversity and change during environmental stressors. This research provides a useful mechanistic understanding for restoring functional ecosystems on large scales. Dr Paul Maxwell Manager Science & Innovation - Healthy Waterways Paul currently leads science and innovation at Healthy Waterways. He is responsible for ensuring that the science underpinning the healthy waterways assessments is rigorous and independent. He is an expert in assessing resilience in coastal ecosystems, particularly the feedback mechanisms that maintain the structure and function of seagrass ecosystems. He has a background in working on integrating science, effective communication and management, including working on the multi-disciplinary Environmental Health Monitoring Program in SE Queensland.
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Dr Ben Diggles Managing Director – Digsfish Services Pty Ltd Ben provides independent aquatic animal health consulting service for the fisheries and aquaculture industries across New Zealand, Australia, Asia and the South Pacific. He is particularly skilled in importing, biosecurity and environmental risk assessment. He also has extensive understanding of environmental management systems, aquatic animal welfare, disease diagnosis in a wide range of aquatic animals, development of feeding attractants for aquaculture and recreational fishing. Ben is collaborating with local fishing groups to spearhead a campaign for restoration of oyster reefs in Pumicestone Passage, SE Queensland. Steve Skull Regional Manager – Alluvium Consulting Steve draws on a 20 year career in natural resource management to work on a diverse array of projects, spanning water resource management and planning, environmental regulation and nature conservation for a wide range of industries including mining and major infrastructure providers. While working for local government he was responsible for the development, delivery and evaluation of environmental policies and programs covering waterway management, climate change, biodiversity, peak oil and sustainability. Steve has also been intimately involved with natural resource management planning and implementation at regional scales. In South East Queensland he was the inaugural chair of the Executive Officers Group supporting the CEOs Committee for NRM. In this role he led the development and coordination of priority projects to ensure the successful implementation of the SEQ NRM Plan. Throughout his career Steve’s work has been recognised by a number of prestigious environmental awards including the International River Foundation’s National Riverprize, the Healthy Waterways Minister’s Grand Prize and the Banksia Awards.
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Dr Simon Walker Director – Ecological Service Professionals Pty Ltd Adjunct Research Associate – The University of Queensland Simon is an aquatic ecologist with an extensive knowledge and understanding of freshwater, estuarine and marine and issues affecting environmental and fisheries management. He is particularly skilled in sustainable resource management, rehabilitation of estuarine and freshwater habitats, biodiversity assessment and constraints mapping, and assessing the adaptive capacity of coastal ecosystems to climate change. Simon has worked on numerous projects that have been pivotal in environmental management decisions of coastal developments, ports and resource projects, particularly in the effective use of marine and freshwater resources coupled with sustainable development. He has broad project experience throughout Australia and in developing countries in the South Pacific. In particular he has recent relevant experience rehabilitation fish habitat in the Maroochy River and restoring saltmarsh and mangrove habitats for the Port of Brisbane and QLD Department of Transport and Main Roads. Bryan DeAngelis North America Coastal Habitat Restoration Coordinator – The Nature Conservancy Bryan DeAngelis has been working in marine restoration , education, research in the US and Caribbean for over a decade. Bryan spent 8 years in coastal habitat restoration as an employee of the National Oceanic and Atmospheric Administration’s Habitat Restoration Center. At NOAA Bryan gained extensive experience developing, managing, and implementing a wide variety of habitat restoration projects and techniques, with a special emphasis on monitoring and measuring project performance. It was with NOAA that Bryan gained his introduction to the bivalve restoration field as the Coordinator of the North Cape Lobster and then later the Shellfish Restoration Programs; two multi-million dollar Natural Resource Damage Assessment projects designed to restore lobster and bivalve resources and services lost due to a large oil spill on the south coast of Rhode Island. In January 2013, Bryan was hired by TNC to serve as the North America Coastal Habitat Restoration Coordinator and to serve as the Coordinator for the National Partnership between TNC and NOAAs Community-based Restoration Program. This Partnership with NOAA has funded nearly 150 restoration projects throughout the US and territories. These projects span the range of habitat types from salmon habitat in the Northwest to coral restoration in Puerto Rico, the US Virgin Islands and Hawaii, with sponge habitat, mangrove, salt marsh, seagrass and plenty of bivalve restoration projects in between.
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Additional experts consulted Jock McKenzie Coordinator – MangroveWatch Hub, Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University Rob Coles Principal Research Scientist – Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University Mike Rasheed Principal Research Scientist – Centre for Tropical Water & Aquatic Ecosystem Research (TropWATER), James Cook University Dr Samantha Miller Principal Policy Officer – Queensland Department of Agriculture, Fisheries and Forestry