Frog Management Plan - Department of Transport and Main Roads

Transcription

Tugun Bypass
Frog Management Plan
Five Year Review
EXECUTIVE SUMMARY
The Tugun Bypass, operating since mid 2008, is a significant section of highway connecting Currumbin (Gold Coast,
Queensland) to Tweed Heads (northern New South Wales). Prior to construction, environmental studies conducted in
the area identified that the alignment would pass through a number of environmentally sensitive areas, potentially
resulting in the loss of known Wallum frog habitat and producing subsequent adverse impacts to the threatened
species. As such, the Bypass was subject to a number of Conditions of Approval aimed at ensuring that the habitat
and local population of two target species, Wallum Froglet (Crinia tinnula) and Wallum Sedge Frog (Litoria
olongburensis), would be conserved throughout construction and operation of the Bypass.
A suite of compensatory and mitigation measures were formulated to address the various potential impacts of the
Bypass. These included, purchase of property containing at least 11ha of habitat for these species to be secured as
conservation “offset”, construction of compensatory ponds adjacent to the Bypass, construction of dedicated frog
underpasses to maintain habitat connectivity, installation of dedicated “frog fencing” to prevent threatened frogs from
accessing the road carriageway and implementation of a detailed monitoring program to confirm the effectiveness of
these measures.
Four compensatory frog ponds were erected throughout the area in order to compensate for habitat compromised by
construction of the Bypass. The ponds were intended to retain and enhance the existing ecological value by
duplicating the Wallum frog habitat through transplantation and re-establishment of existing vegetation and core
ecosystem components. Compensatory ponds and existing habitats were monitored during construction and for three
years following the commencement of operation, the effectiveness of which was measured against a number of
performance criteria stipulated in the projects’ Environmental Impact Statement (EIS) and Species Impact Statement
(SIS).
Additionally, three frog underpasses were constructed in order to maintain connectivity between areas of Wallum frog
habitat east and west of the alignment, and permanent frog exclusion fences were constructed to reduce the potential
for an increase in frog mortality resulting from construction of the Bypass and traffic during operation. Monitoring of
these structures occurred seasonally in conjunction with frog pond monitoring.
Results indicated that while some of the water quality parameters in the compensatory ponds were not ideal for
Wallum frog breeding, both target species continue to persist in the area. Sub-adults and calling males were
recorded at existing breeding ponds, demonstrating that reproduction is occurring in these areas; however, results for
the compensatory ponds showed that threatened frog numbers were low.
Tugun Bypass – Frog Management Plan
Page i
Both target species were recorded around the entrances of two of the three culverts, suggesting that movement
through culverts between the east and west sides of the highway are likely to be occurring. Failure to record any road
killed frog species during daily road kill inspections was not considered a suitable indicator to assess the
effectiveness of the frog fences in excluding frogs from entering the motorway.
Overall, the frog monitoring program was considered to be a success. While there were variable results in some
elements, threatened frog populations appear to be persisting throughout the Bypass area, and the mitigation
measures utilized are likely to have contributed to this result.
It was recommended that compensatory ponds and frog underpasses be considered for inclusion as part of
mitigation on future projects. The design of compensatory ponds for future projects could be altered to allow greater
interception of groundwater, which may result in a greater hydro period and improved water chemistry.
Monitoring of road frog mortality associated with active, operation roads should be discontinued and not be
considered for future projects as it is ineffective and represents an unacceptable OH&S risk to the staff conducting
the survey.
Page ii
TABLE OF CONTENTS
1
2
3
4
Introduction ...........................................................................................................................................................1
1.1
Background - The Tugun Bypass Project ................................................................................................1
1.2
Threatened Frogs ....................................................................................................................................2
1.3
Context of the report ................................................................................................................................4
1.4
Conditions of Approval ............................................................................................................................4
1.5
Previous Reports .....................................................................................................................................7
Mitigation and management Measures .................................................................................................................9
2.1
Purchase of “Offset” Habitat Area............................................................................................................9
2.1.1
Purpose ...................................................................................................................................................9
2.2
Frog Ponds ............................................................................................................................................10
2.2.1
Purpose .................................................................................................................................................10
2.2.2
Design ...................................................................................................................................................10
2.2.3
Performance Criteria .............................................................................................................................11
2.3
Frog Underpasses .................................................................................................................................12
2.3.1
Purpose .................................................................................................................................................12
2.3.2
Design ...................................................................................................................................................12
2.4
Frog Fences ..........................................................................................................................................12
2.4.1
Purpose .................................................................................................................................................12
2.4.2
Design ...................................................................................................................................................13
Monitoring methods.............................................................................................................................................14
3.1
Frog Ponds ............................................................................................................................................14
3.2
Construction ..........................................................................................................................................15
3.3
Operation ...............................................................................................................................................16
3.4
3.5
Frog Fencing .........................................................................................................................................17
Results ..................................................................................................................................................................1
4.1
Compensatory Frog Ponds ......................................................................................................................1
4.2
Hydroperiod ...........................................................................................................................................19
4.3
Acidity/pH ..............................................................................................................................................19
4.4
Electrical conductivity ............................................................................................................................19
4.5
Presence of frogs ..................................................................................................................................20
4.6
Pest fish species....................................................................................................................................20
Page iii
5
6
7
4.7
4.8
Frog Exclusion fences ...........................................................................................................................25
4.9
Population Status ..................................................................................................................................25
Discussion ...........................................................................................................................................................28
5.1
Frog Ponds ............................................................................................................................................28
5.1.1
Hydroperiod ...........................................................................................................................................28
5.1.2
Acidity/pH ..............................................................................................................................................28
5.1.3
Electrical Conductivity ...........................................................................................................................29
5.1.4
Pest Fish Species ..................................................................................................................................29
5.1.5
Frog usage ............................................................................................................................................29
5.2
5.3
Frog Exclusion Fences ..........................................................................................................................30
5.4
Population Status ..................................................................................................................................31
5.5
Monitoring Variability .............................................................................................................................32
Conclusions.........................................................................................................................................................33
6.1
Compensatory ponds ............................................................................................................................33
6.2
Frog Exclusion Fences ..........................................................................................................................33
6.3
6.4
Compensatory habitat ...........................................................................................................................34
6.5
Monitoring Program ...............................................................................................................................34
6.6
Recommendations.................................................................................................................................34
6.6.1
Compensatory Ponds ............................................................................................................................34
6.6.2
Frog Exclusion fence .............................................................................................................................34
6.6.3
6.6.4
Compensatory Habitat ...........................................................................................................................35
6.6.5
Monitoring Program ...............................................................................................................................35
References ..........................................................................................................................................................36
Appendix A – Raw Data ...............................................................................................................................................38
Appendix B – Photos....................................................................................................................................................47
Appendix c – Compensatory Habitat Selection ............................................................................................................53
Appendix D – Design Drawings ...................................................................................................................................54
Page iv
1 INTRODUCTION
1.1 Background - The Tugun Bypass Project
The Tugun Bypass is a section of motorway (approximately 7km long) connecting the Pacific Motorway at Stewart
Road (Currumbin) in Queensland to Kennedy Drive (Tweed Heads) in New South Wales. It has a four-lane restrictedaccess motorway with a central median to separate north– south traffic flows at a posted speed of 100 km/h. Other
features of the Bypass include:
 a central median wide enough to allow upgrading to six lanes in the future;
 a road tunnel 334 meters long beneath the extension of Gold Coast Airport’s main runway;
 a grade-separated interchange on the Tweed Heads Bypass;
 bicycle and pedestrian lanes at The Tweed Heads Bypass interchange and Stewart Road interchange;
 Motorway bridges over Hidden Valley; and
 access bridges for the proposed Cobaki Lakes Development and Gold Coast Airport Limited (GCAPL).
The Tugun Bypass alignment passes through/lies adjacent to, a number of areas that were identified in the
Environmental Impact Statement (EIS) and Species Impact Statement (SIS) as having a high environmental value.
These environments included protected wetlands, significant vegetation communities, culturally significant areas and
areas containing threatened flora species and fauna habitat.
Prior to commencement of operation, an Operational Environmental Management Plan (OEMP) was prepared,
addressing all environmental issues associated with the operational and maintenance phase of the project.
Construction of the Bypass was completed in June 2008 and is now in the 4th year of Operation. Queensland
Department of Transport and Main Roads (DTMR), in conjunction with New South Wales Roads and Traffic Authority
(RTA), are responsible for monitoring and maintenance during the Operational phase of the Project.
Page 1
Figure 1. Tugun Bypass alignment
1.2 Threatened Frogs
Prior to construction of the Tugun Bypass, two acid frog species; Wallum froglet (Crinnia tinnula) and Wallum sedge
frog (Litoria olongburensis) were identified occurring within the Gold Coast Airport boundary as well as within and
adjacent to the Tugun Bypass Project footprint (Hero et al. 2001). According to preceding studies throughout the
area, this Gold Coast Airport Leasehold Land at Tugun provides the only known location for the Wallum sedge frog
on mainland Australia between Brisbane and New South Wales, with the next closest mainland populations occurring
30-40km south at Hastings Point-Pottsville area (Hero et al. 2001) and 100km north at Beerwah (Liem and Ingram
1997).
The group of frogs referred to as ‘acid’ frogs are a unique assemblage restricted to areas of coastal Wallum along the
east coast of Australia (Lewis and Goldingay, 2005). They are often associated with characteristic Wallum vegetation
communities including Banksia and Leptospermum woodland, Melaleuca swamp, sedge-land and heath-land (Hines
et al. 1999). The name ‘acid’ frog is based on the unusually low pH (high acidity) conditions required by the species
for breeding. They typically breed in ponds with a pH between 4.3 and 5.2 and are very sensitive to other changes in
Page 2
their environment such as drainage, interference with water tables, nutrient pollution and habitat clearance (Ingram
and Caneris, 2005).
Wallum sedge frog
The Wallum sedge frog is commonly found within swamps, creeks and freshwater lakes, seeking refuge amongst
sedges, reeds and ferns. Breeding occurs following rainfall in spring, summer and autumn, while males can be heard
calling from September through to April (DERM, 2011). Breeding sites vary in location, depending on the amount of
rain and surface water, but generally occur within heath plains and forest or woodland (Ingram and Caneris, 2005).
The Wallum sedge frog is of national significance. It has a status of Vulnerable under the NSW Threatened Species
Act 1995, Queensland Nature Conservation (Wildlife) Regulation 1994, and the Commonwealth Environment
Protection and Biodiversity Conservation Act 1999 (DERM, 2011).
While there was some difference between studies on the distribution and breeding areas of the Wallum sedge frog on
existing airport land and surrounding areas, the population was estimated to be small, consisting of approximately 80
individuals prior to construction, with six sub-populations occurring to the east and west of the runway (Ingram and
Caneris 2005). Lower vegetation strata associated with the acid frog of this area are characterised by Blechnum
species, sedges and heath-land species (Hopkins, 2003).
Wallum froglet
The Wallum froglet typically inhabits freshwater swamps in lowland coastal areas and associated vegetation
communities such as heath, sedgeland and woodland, where acidic swamps and lakes provide essential breeding
habitat. Breeding usually occurs in autumn or early winter, though calling males have been recorded in all seasons
following rain.
Pre-construction surveys found the Wallum froglet to be relatively widespread throughout the subject area, with high
densities occurring throughout patches of open Wallum vegetation and associated grasslands east of the proposed
footprint. It is also found in lower densities throughout remaining closed canopy Wallum habitat west of the proposed
alignment, with an overall population estimated to comprise about 10,000 individuals (Hero, et al, 2005).
The Wallum froglet is currently listed as Vulnerable under the NSW Threatened Species Act 1995 (DERM, 2011).
Page 3
1.3 Context of the report
Historical data recorded throughout the Tugun Bypass footprint area indicated a low abundance of Wallum sedge
frog, such that the population may be unviable in the long term (Australian Wetlands, 2006). Construction of the
Tugun Bypass resulted in the loss of approximately 2ha of known Wallum frog habitat (Australian Wetlands, 2006),
dividing the metapopulations of both species into east and west sub-populations.
Given the vulnerability of the population, which was already highly constrained by existing development and
environmental conditions, preservation of the species and species habitat was considered a high priority. As a
requirement of the Conditions of Approval for commencement of the project (section 1.4), a number of Wallum frog
conservation measures were undertaken to prevent frog mortality and to compensate for habitat areas affected by
the Bypass (Pacific Link Alliance, 2006).
The following report has been prepared to satisfy the requirements of Condition of Approval No 2 (b) (Section 1.4)
and the New South Wales Department of Planning as a review of the management measures implemented and
subsequent monitoring events undertaken throughout construction and operation of the Tugun Bypass. The
effectiveness of management will be discussed, highlighting how local populations of the Wallum species have been
influenced by the Project.
1.4 Conditions of Approval
Prior to commencement of the Bypass, a Frog Management Plan (Pacific Link Alliance, 2006) and Compensatory
Habitat Package (SMEC, 2009) were prepared in order to meet relevant Conditions of Approval sourced from the
NSW Department of Planning, the Commonwealth Department of Transport and Regional Services (DoTaRS), the
Commonwealth Department of Environment and Heritage (DEH), the Major Development Plan (MDP) prepared by
GCAL and the original Statement of Commitments from the Project MDP.
Conditions of Approval relevant to the management of threatened frogs are outlined in table 1.
Page 4
Table 1. Summary of Conditions of Approval
Source
Condition
Commonwealth
The person taking the action must prepare and implement plans addressing the requirements
Department of
outlined below for the conservation of the Long-nosed Potoroo and the Wallum Sedge Frog. The
Environment and
plans must be submitted to the Minister for approval and construction may not occur until the
Heritage (DEH).
Minister approves them.
(Approval under
b) Wallum Sedge Frog:
EPBC Act 1999)
Measures to prevent frog mortality during construction and a translocation protocol. These
Condition of Approval
measures must provide for a trial of temporary frog fencing and if successful, the establishment of
No 2.
a permanent frog fence;
Construction of at least three purpose built frog ponds during the construction of the Tugun
Bypass. The specifications for these ponds must be consistent with those set out in Appendix A of
the compensatory habitat report; September 2005 (Appendix H of the supplement to the Draft
EIS):
Construction of culverts to maintain connectivity between areas of Wallum Sedge Frog habitat on
either side of the alignment. The plan must demonstrate how the design of the culverts will
maximise their use by Wallum Sedge Frogs;
A Wallum Sedge Frog monitoring program to measure the effectiveness of ponds, fencing and
underpasses and to monitor the status of the population with annual reporting to relevant
government agencies for the first five years;
A process for reviewing monitoring information and developing any remedial actions; and
A requirement for a five year public review of the management plan.
Page 5
Statement of
The Proponent would ensure that measures to minimise impacts on the Wallum Sedge Frog is
Commitment (from
detailed within the Threatened Species Management Plan. The plan would be developed in
Submission Report)
consultation with the Environmental Review Group described in Section 35 of the SIS. The plan
would also incorporate measures described within Tugun Bypass, Stewart Road to Kennedy Drive
Statement of
– Compensatory Habitat (QDMR 2005).
Commitment No. 11
– Wallum Sedge
The plan would include pre-construction, construction and post-construction management
Frogs
measures. The pre-construction management measures would be implemented prior to
construction and would include, but not be limited to the following:
 Measures to prevent frog mortality during construction would be determined and specified for
implementation during Detailed Design. Such measures may include temporary frog fencing
or, if practical the early implementation of sections of permanent frog fence.
A hygiene protocol for contractors to minimise the spread of the amphibian chytrid fungus would
be developed consistent with NSW Department of Environment and Conservation’s Hygiene
Protocol for the Control of Disease in Frogs.
The construction management measures described in the plan would be implemented throughout
the various stages of construction and would include, but not be limited to the following:
 A total of three, purpose built artificial frog ponds would be constructed as early as practical in
association with construction of the Bypass.
 The minimum size of the frog ponds would be 15-20m in length and 5-10m in width.
 Construction works for the artificial frog ponds would be undertaken during a dry period
(spring) leading up to a pronounced rainfall event (normally summer).
 Edges of the ponds would be planted with species consistent with the local habitat
requirements for Wallum Sedge Frog (such as Restio species) from the alignment. Vegetation
would be removed by a process known as “slabbing”. Slabbing depth would be at least 30cm
to ensure organic layers are collected. The source sites for slabbing would include any existing
Restio vegetation at the artificial pond sites and where applicable, augmented from areas with
dense Restio along the proposed alignment.
 Two culverts would be constructed under the Bypass to maintain connectivity between areas of
Wallum Sedge Frog habitat on either side of the alignment. These culverts would be 1m high
and 3m wide, with their length varying between 50 and 60m. The design of the base of the
culverts would need to encourage the use of these structures by frogs. One option is to include
a central channel in the culvert that would hold water.

Page 6
 Frog exclusion fencing would be constructed to keep frogs off the road and direct them into the
culverts. This fencing would be of durable construction with a small overhang at the top.
Constructed wetlands would be revegetated with native species characteristic of the area. Where
possible, wetland vegetation from areas to be disturbed would be used.
The post-construction management measures described in the plan would be implemented after
the completion of various stages of construction and would include, but not be limited to the
following:
 A Wallum Sedge Frog monitoring program to measure the effectiveness of ponds, fencing and
underpasses would be consistent with the Tugun Bypass, Stewart Road to Kennedy Drive –
Compensatory Habitat (QDMR 2005) report and recommendations provided by the
Queensland Environmental Protection Agency, NSW Department of Environment and
Conservation, Commonwealth Department of Environment and Heritage and/or
Commonwealth Department of Transport and Regional Services depending on jurisdiction.
Monitoring would commence once the ponds, fences and underpasses have been
commissioned and would cease once it has been determined by a qualified ecologist that they
are effective. The Operation Environmental Management Plan would contain procedures for
reporting and remedial action should it be necessary.
1.5 Previous Reports
Wallum frogs have been studied intensively within the Tugun Bypass/Gold Coast Airport area prior to approval and
since the commencement of construction and operation of the Bypass. The following documents prepared as part of
the impact assessment and monitoring for the project have been referenced in this report:

Tugun Bypass Environmental Impact Statement (EIS) and associated Technical Papers (Tugun Bypass
Alliance, 2004);

Tugun Bypass, Species Impact Statement (SIS) and Equivalent Studies under Relevant Queensland and
Commonwealth Environmental Legislation (Tugun Bypass Alliance, 2004);

Wallum Sedge Frog (Litoria olongburensis) Wetland Habitat Translocation (Australian Wetlands, 2006)

Frog Management Plan (FMP) for the Tugun Bypass (Pacific Link Alliance, 2006)

Frog Monitoring during the first and final phase construction of the Tugun Bypass, April 2006-November
2007 (Hero and Simpkins, 2008);
Page 7

Operational Environmental Management Plan (OEMP) (Pacific Link Alliance, 2008)

OEMP, PLA718 – Threatened Frog Management (Abigroup Limited, 2008)

Tugun Bypass Frog Monitoring Report, Summer and Autumn 2008-2009 (Sandpiper Ecological Surveys,
2009)

Tugun Bypass Frog Monitoring Report, Summer and Autumn 2010 (Sandpiper Ecological Surveys, 2010)

Environmental Impact Audit Report: Operations (Pacific Link Alliance, 2010)
Page 8
2 MITIGATION AND MANAGEMENT MEASURES
In response to the Conditions of Approval, a management strategy was developed and a suite of mitigation and
management measures were evaluated, designed, tested and implemented. The following section outlines the key
components of this set of actions.
2.1 Purchase of “Offset” Habitat Area
2.1.1 Purpose
A study by SMEC (2009) was undertaken to identify sites within 100 kilometres of the Tugun Bypass project that
would be potentially suitable for acquisition as compensatory habitat. The investigation sought to address the
requirement to find and acquire approximately 11 hectares of “offset” habitat for three target species, namely the
Wallum sedge frog, Wallum froglet and Common planigale.
A range of potentially suitable sites across Qld and NSW and within the search radius were assessed through a multi
step approach using Geographical Information Systems (GIS) and qualitative assessment methods. The GIS
analysis comprised an initial assessment, and a detailed spatial analysis using more accurate and comprehensive
spatial data, which allowed a greater capacity for selection of individual sites.
A qualitative analysis was carried out on the final 20 candidate sites to identify Local Environment Plan (New South
Wales) or Planning Scheme (Queensland) constraints, and to verify the results of the GIS analysis using aerial
photography. Based on both the quantitative and qualitative assessments, candidate sites that had potential as
compensatory habitat for the target species were designated as “Potentially Suitable” and all other sites were
deemed “Sub-optimal”. Six (6) “Potentially Suitable” candidate sites were short listed and an aerial assessment and
detailed on-ground assessment was undertaken.
On-ground investigations revealed hat all three target species inhabited Site 19 (Lot 195 DP755624). Site 18 (Lot 2
DP604378) supported both frogs and was considered highly likely to support Common Planigale (Lewis, 2008).
Based on the outcomes of both the desktop assessment and on-ground investigations, two sites (Site 18 (Lot 2
DP604378) or Site 19 (Lot 195 DP755624)) were found to provide suitable compensatory habitat for all three target
species. Contact was made with land owners, and Site 18 was purchased by DTMR in late 2009.
Full details of the selection process are included as Appendix C.
Page 9
2.2 Frog Ponds
2.2.1 Purpose
The Environmental Impact Statement (EIS) prepared for the project, indicated that construction of the Bypass was
expected to result in the direct loss of Wallum sedge frog habitat, as well as indirectly impacting on a number of other
sites during construction/operation. As such, construction of compensatory Wallum sedge frog breeding ponds within
the Bypass footprint was undertaken in order to offset the impacts.
While few attempts have been made to construct artificial breeding areas for Wallum frogs, it is widely acknowledged
that the species’ are capable of rapidly re-colonising disturbed areas, provided that physical characteristics of the
water bodies (i.e. shallow sandy soils, low pH and electrical conductivity) are suitable (SMEC, 2009). Implementation
of artificial breeding ponds as compensation for natural habitat lost to construction of the Bypass was therefore
considered feasible and likely to be a success (Ingram and Caneris, 2005).
The compensatory ponds aimed to duplicate the Wallum frog habitat by transplanting and re-establishing the existing
vegetation and core ecosystem components of the remnant wetland habitats, thereby retaining the ecological value
which was compromised for construction of the Bypass (Australian Wetlands, 2006).
2.2.2 Design
Construction of the compensatory habitats was largely experimental. The design requirements and locations were
determined by a team of environmental consultants based on characteristic habitat requirements of Wallum frog
species such as hydrology (pH, salinity, hydro period), surrounding and aquatic vegetation, presence of predators,
and proximity to existing natural habitat areas. Constraints such as Acid Sulphate Soils (ASS) and the high
groundwater table of the site were also considered.
Four artificial frog ponds (one more than required under approval conditions) were designed to be constructed along
the new road alignment. The fourth pond was a largely experimental design and was constructed outside the
statutory requirements of the Project (Pacific Link Alliance, 2010).
Based on the existing site conditions, the ponds were placed above the natural ground level, limiting the potential of
exposure to ASS, and a water level control device (see Figures 5 and 6 – Appendix B) was installed to maintain
water levels in the ponds so that plant health and weed invasion could be managed (Australian Wetlands, 2006).
Page 10
The newly constructed wetlands were strategically located between isolated natural breeding ponds and existing
habitat, in order to maintain connectivity between local populations and habitats. Lewis and Goldingay (2005)
reported that Wallum sedge frogs will migrate short distances to colonise suitable areas after disturbance.
Construction of the ponds included the physical translocation of suitable vegetation (consistent with the local habitat
requirements for the Wallum sedge frog) from the footprint to adjacent rehabilitation areas (Pacific Link Alliance,
2006).
Photos of the constructed compensatory frog ponds can be seen in Appendix B (Figures 1 – 4). Drawings are
included as Appendix D.
2.2.3 Performance Criteria
As part of the Tugun Bypass Compensatory Habitat Package and as detailed in the Compensatory Habitat report
(DTMR, 2005), a number of recommendations were provided based on observations made during field and
laboratory work that focused on the compensatory frog ponds along the Tugun Bypass Project. These included:
 Ponds should generally be shallow and constructed in areas of high groundwater;
 Water quality should exhibit the following characteristics:
- pH <5 (as influenced by humic acids);
- hardness <100 p.p.m; and
- salinity <350 µS/cm.
 Ponds should be ephemeral to prevent habitation by fish but have a minimum hydroperiod of four to six
weeks for Wallum froglets and eight weeks for Wallum sedge frogs;
Pond fringes should be densely planted with emergent species to prevent predation by Cane Toad (Rhinella marina).
The following four (4) performance criteria were developed as part of the Compensatory Habitat Report (DTMR,
2005) to provide a means to determine success of the compensatory ponds based upon monitoring results:
 Ponds are to contain surface water for a period of >10 weeks per annum, for at least two (2) of the three (3)
year monitoring periods;
 Waters within ponds are to have a pH <5 and an electrical conductivity (EC) <350 µS/cm;
 Ponds are to contain a margin of emergent macrophytes >200mm thick, and
Ponds are not to contain fish.
Page 11
These criteria and recommendations address the known acceptable conditions suitable to sustain breeding
populations of acid frog species particularly Wallum frog species. The four (4) performance criteria will be used in this
report to assess the current conditions and success of the compensatory ponds as at May 2011.
2.3 Frog Underpasses
2.3.1 Purpose
A number of fauna underpasses were constructed along the bypass in order to maintain connectivity between areas
of Wallum frog habitat east and west of the alignment, thereby reducing the impact of the barrier effect. The
underpasses also act as a passage of movement for additional species such as Common planigale.
2.3.2 Design
Three frog culverts were constructed under the Bypass (Chainage 4045, 4600 and 4940), measuring 1m high and
3m wide, with lengths varying between 50 and 60m (Pacific Link Alliance, 2010). A natural substrate was provided by
placing 25mm of mulch on the culvert floor, and refuge points were provided by strips of shade cloth installed at
regular intervals within the underpass. Additionally, enhancement of habitat around the entrances to the culverts was
undertaken through landscaping with native sedges and grasses.
This was an experimental design. Monitoring methods for the frog underpasses are detailed in Section 3.2.
2.4 Frog Fences
2.4.1 Purpose
In order to reduce the potential for an increase in frog mortality resulting from construction of the Bypass and traffic
during operation, and to guide frogs into the culverts, frog exclusion fencing was constructed along the eastern and
western sides of the road. Permanent fences were erected in areas identified as high risk, based on the presence of
known and potential Wallum frog habitat.
Page 12
2.4.2 Design
During the initial planning stage of the Bypass, the following design requirements were recommended:

A barrier wall that measures at least 400mm in height to prevent frogs jumping over the fence;

A roof and lip structure shall be attached to the top of the barrier. The 45degree sloping roof section should
be 155mm long with an additional piece bent at 45° to form a 30mm lip;

No vegetation allowed within 1m over either side of the frog fence that would facilitate frog movement over
the fence; and

The design life of the frog fence should be 20years
Three combined fences and eight road embankment fences were trialled using a wide range of building materials in
order to select the most effective design to meet these requirements. Difference fence types were used in certain
locations based on habitat linkages, drainage and topography, with results being used to refine the fence design
where suitable.
Temporary fencing of the project footprint was also adopted during construction with the aim of minimising physical
impacts and protecting adjacent habitats.
Road embankment frog fence
Materials used for the road embankment fencing were recycled plastic planks supported by recycled plastic posts.
The 45° angle attached to the top of the frog exclusion fence was a pre-fabricated galvanised sheet formed to the
shape (Figure 7 – Appendix B) recommended by Ingram and Caneris (2005).
While this was not the most economical option, the benefits outweighed this drawback in that the materials were
recycled, durable and could be coloured to blend in with the natural surroundings (Pacific Link Alliance, 2007).
Frog fence incorporated into other fencing
Materials used for this fence was a 5mm insertion rubber, which is clamped to a galvanised backing plate on the
fauna/airport security/boundary fence used for other purposes. A galvanised angle is also attached to the top of the
5mm insertion rubber, galvanised backing plate and chain wire mesh (Figure 8 – Appendix B).
The advantages of this design were that it was easily constructed, durable, economical and proven to be effective.
Design drawings of the frog exclusion fences are included as Appendix D.
Page 13
3 MONITORING METHODS
3.1 Frog Ponds
The study site comprised four (4) compensatory ponds along the Tugun Bypass (Figure 2). Four (4) established
breeding ponds within the Gold Coast Airport Leasehold Land and one (1) drainage channel were also monitored in
order to give an indication of the general population status of the area.
Figure 2: Location of existing and compensatory frog ponds and drainage
system along the Tugun Bypass (Hero &Simpkins, 2008).
Page 14
The following pond identification naming system was adopted throughout all monitoring events:
Table 2: Pond and drain identification naming system has been adopted throughout all monitoring events.
Site Name
Habitat Type
Abbreviation
Monitoring 3
Existing Pond
M3
Monitoring 4b
Existing Pond
M4b
Monitoring 5
Existing Pond
M5
Monitoring 6
Existing Pond
M6
Compensatory 1
Compensatory Pond
C1
Compensatory 2
Compensatory Pond
C2
Compensatory 3
Compensatory Pond
C3
Compensatory 4
Compensatory Pond
C4
Drain 1
Drain
D1
Previous surveys by Hopkins (2003) and Lewis (et al. 2005), observed significant positive relationships between
Wallum frogs and rainfall events, therefore all sampling was conducted, where possible, after heavy weekly rainfall.
Weather conditions were assessed via the Bureau of Meteorology (BOM) website prior to each monitoring survey to
ensure rainfall had occurred within seven days to any monitoring event,
3.1.1 Construction
During construction (April 2006 – April 2008), both compensatory and established monitoring ponds were surveyed
monthly between 4:00pm and 9:15pm, as optimal calling activity for these target species has been found to occur
between 6pm and 8pm (Hopkins 2003). Surveying commenced in April 2006 at the established monitoring ponds,
September 2006 at the compensatory ponds and August 2006 at the drainage channel. Each pond was surveyed by
1-4 people for a minimum of ten minutes with start and end time recorded. Survey techniques included acoustic and
visual observations for all species as well as playback (using a hand held digital tape recorder) for target species.
Additional species of amphibian were recorded, along with the presence of Mosquito Fish (Gambusia) when
observed at the sites.
Page 15
When water was present during surveys, the following abiotic pond characteristics were measured using a water
quality meter:

pH;

conductivity;

temperature;

salinity;

turbidity;

dissolved oxygen; and

Water level/depth.
Daily precipitation and maximum daily temperature data (since March 2006) was obtained from the BOM Coolangatta
Rainfall Monitoring Station (Station 040717), the closest rainfall monitoring station to the Tugun Bypass
(approximately 3km south-east).
3.1.2
Operation
A combination of acoustic and visual, targeted frog surveys using the same techniques described for construction
were conducted twice within each of the following time periods during operation:

December 2008 (Summer)

April 2009 (Autumn)

February 2010 (Summer)

May 2010 (Autumn)

April 2011 (Autumn)
Commencing at dusk, approximately 20 minutes was spent surveying each site. Calls of Wallum Froglet and Wallum
Sedge frog were broadcast intermittently through a megaphone with a handheld digital media player for 4 minutes
over a 15 minute period, with time spent listening for response calls between playbacks. Visual surveys targeted
sedge stems and low ground vegetation with shallow water. Additional amphibian species seen or heard were
recorded. Fish and tadpole observations were also recorded when present at the survey sites (Rohweder, 2008).
As recommended in the Frog Management Plan, a precautionary approach was taken during sampling, and a
hygiene protocol was prepared (in accordance with the NSW Department of Environment and Conservation’s
Hygiene Protocol for the Control of Disease in Frogs) to consider all relevant site personnel in order to minimize the
risk of spreading amphibian Chytrid fungus.
Page 16
The entrances/exits to the frog culverts were monitored using pitfall traps, undertaken in conjunction with seasonal
frog pond monitoring, at least once during the breeding season of each threatened frog species. Monitoring was
carried out following rainfall events where possible, as frogs are likely to be most active at this time (Rohweder,
2009).
Pitfall trapping was conducted in April/May 2009 and June 2010. In 2009, pitfall lines (two 20L pitfall buckets and a
drift fence) were installed at both ends of the three frog underpasses, with the drift fence extending across the
entrance ensuring that it was encountered by any frogs moving into or out of the culverts.
Methods of the 2010 surveys were adjusted slightly as recommended by Sandpiper Ecological Surveys (2009). One
pair of pitfalls was situated on the underpass side of the drift fence (referred to as ‘inside’) to capture frogs moving
through and the other was situated on the outside of the drift fence (refered to as ‘outside’) to capture frogs moving
towards the underpass. Trapping was conducted over four consecutive nights on three separate occasions, with
timing and duration influenced by weather conditions, particularly rainfall.
A large rock, moist soil and a piece of polystyrene was placed in each pitfall and the soil was moistened each
morning during both monitoring events. Traps were covered with lids in between monitoring periods to prevent
animals from becoming trapped (Rohweder, 2010).
3.3 Frog Fencing
Active searches for frogs along the road side of the frog exclusion fences, and assessment of the fence condition
was to be undertaken by the maintenance contractor monthly for the first year of operation (Abigroup Ltd, 2008).
However, no records were provided regarding breaches, maintenance, or the presence of frogs, suggesting that
monitoring did not occur. While road kill data for all animal species was collected daily by the maintenance
contractor, road-killed frogs are likely to be too small to be seen.
Page 17
4 RESULTS
4.1
Compensatory Frog Ponds
As indicated in Figure 3, monthly rainfall fluctuated consistently throughout the period of monitoring, with a dry period experienced between August and November
2009. Sufficient rain occurred during or immediately prior to frog surveys in all monitoring events.
Monthly Rainfall
600
Commencement of
Operation
Rainfall
Pond Monitoring
500
400
300
200
100
May-06
Jun-06
Jul-06
Aug-06
Sep-06
Oct-06
Nov-06
Dec-06
Jan-07
Feb-07
Mar-07
Apr-07
May-07
Jun-07
Jul-07
Aug-07
Sep-07
Oct-07
Nov-07
Dec-07
Jan-08
Feb-08
Mar-08
Apr-08
May-08
Jun-08
Jul-08
Aug-08
Sep-08
Oct-08
Nov-08
Dec-08
Jan-09
Feb-09
Mar-09
Apr-09
May-09
Jun-09
Jul-09
Aug-09
Sep-09
Oct-09
Nov-09
Dec-09
Jan-10
Feb-10
Mar-10
Apr-10
May-10
Jun-10
Jul-10
Aug-10
Sep-10
Oct-10
Nov-10
Dec-10
Jan-11
Feb-11
Mar-11
Apr-11
0
Figure 3. Total Monthly Rainfall (Coolangatta) April 2006 to April 2011
Page 18
Figures 4 through to 6 illustrate the key water quality parameters of surface water levels (hydroperiod), pH and
electrical conductivity measured in the compensatory ponds during each monitoring event, as they correlate to
rainfall.
4.2
Hydroperiod
Ponds C1 and C3 contained sufficient water on all occasions of monitoring (Figure 4). These two sites follow similar
patterns of variation which, as expected, appear to mirror rainfall.
While only small amounts of water were recorded in pond C4 during construction, levels appeared to increase
following rainfall in March 2010.
Pond C2 consistently contained little or no water during construction and operational monitoring events. Due to
inaccessibility of this pond at the time of sampling, the water level and physical parameters of pond C2 could not be
determined in April 2011.
4.3
Acidity/pH
While pH levels of compensatory ponds varied between sites during construction (Figure 5), all sites appeared to
follow a similar pattern throughout operation, measuring below the performance criteria of 5 on only one occasion
(April 2009).
It should be noted that pH was not measured in pond C2 in April 2010 and pond C4 in February 2010 due to
inaccessibility and lack of available water, respectively, within the ponds at the time of monitoring.
4.4
Electrical conductivity
As shown in Figure 6, electrical conductivity in the compensatory ponds was highly variable between and within sites,
appearing to coincide with rainfall on some occasions. EC values at C2 and C4 remained below the stipulated value
of 350µS/cm during operation, despite an initial peak in October 2006. C1 followed a similar pattern, with the
exception of one recording above 350µS/cm in April 2010. Pond C3 displayed consistently higher electrical
conductivity concentrations, regularly exceeding the stipulated value.
As for pH, electrical conductivity could not be measured within pond C2 in April 2010 and pond C4 in February 2010.
Page 19
4.5
Presence of frogs
The Compensatory Habitat Package and supporting documentation indicates that, if the stipulated performance
criteria are being met, the ponds should contain active calling Wallum froglets and/or Wallum sedge frogs during
surveys.
Despite suitable weather conditions at the time of surveys, no Wallum sedge frogs were observed (visually or
acoustically) at the compensatory ponds during monitoring events (Appendix A). Wallum froglets, appeared to be
persisting during construction, however, only one individual was recorded on a few occasions in pond C1 and C3
during operation. It should be noted that monitoring was undertaken monthly during construction, and only seasonally
during operation.
4.6
Pest fish species
Mosquito fish (Gambusia hlbrooki) were recorded at pond C3 between December 2008 and April 2009, and once in
May 2010 (Table 3).
Table 3. Presence of fish within compensatory ponds during operational monitoring events.
Site
C1
3-Dec08
Absent
10-Dec08
Absent
6-Apr09
Absent
28-Apr09
Absent
11-Feb10
Absent
18-Feb10
Absent
4-May10
Absent
6-May10
Absent
13-Apr11
Absent
14-Apr11
Absent
C2
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Absent
C3
Present
Present
Present
Present
Absent
Absent
Present
Absent
Absent
Absent
C4
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Absent
Page 20
Surface Water Level
0.5
160
Commencement of
Operation
0.45
140
0.4
120
100
0.3
0.25
80
0.2
Rainfall (mm)
Water Level (m)
0.35
60
0.15
40
0.1
20
0.05
0
0
C1
C2
C3
C4
Rainfall
Figure 4. Surface Water Levels in Compensatory Ponds (April 2006 –April 2011)
Page 21
pH
160
Commencement of
Operation
7
140
6
120
5
100
4
80
3
60
2
40
1
20
0
0
C1
C2
C3
C4
Upper Limit
Rainfall (mm)
pH
8
Rainfall
Figure 5. pH in compensatory ponds
Page 22
Electrical Conductivity
1600
160
1400
140
1200
120
1000
100
800
80
600
60
400
40
200
20
0
Rainfall (mm)
EC (uS/cm)
Commencement of
Operation
0
C1
C2
C3
C4
Upper Limit
Rainfall
Figure 6. Electrical conductivity in compensatory ponds
Page 23
The fauna culverts were inspected on four separate occasions during operation. In total, five amphibian species
were recorded during the 2009 and 2010 pitfall surveys. Wallum froglets were recorded east of culverts 1 and 3
and Wallum sedge frogs were captured on both sides of culvert 3 during the 2009 surveys, however neither of
these target species were recorded in 2010 (Table 4 and 5).
As highlighted in Section 3.2 , monitoring methods were modified after the 2009 surveys, such that during 2010,
pitfall traps were positioned either side of the drift fence, but only at one end of each culvert.
Table 4. Pitfall Survey Results (2009)
Date
C1 (CH 4045)
East
29 April 2009
West
1 Wallum
C2 (CH 4600)
East
West
2 Cane Toads
froglet
C3 (CH 4940)
East
West
1 Cane Toad;
1 Rough-
1 Wallum
scaled Snake
froglet
30 April 2009
1 May 2009
1 Eastern
1 Wallum
water dragon
sedge frog
2 Cane Toads
1 Cane Toad;
1 Garden
1 Wallum
skink
sedge frog
2 May 2009
2 Cane Toads
1 Robust
striped skink
Table 5. Pitfall Survey Results (2010)
Date
C1 (CH 4045)
Inside
Outside
12 Feb 2010
1 House mouse
13 Feb 2010
1 Striped marsh
C2 (CH 4600)
Inside
Outside
C3 (CH 4940)
Inside
Outside
Cane Toad
frog & 1 Ornate
burrowing frog
19 Feb 2010
3 Cane Toad
20 Feb 2010
1 Cane Toad
21 Feb 2010
2 Cane Toad
5 June 2010
1 Rough-scaled
1 House
tiger snake
mouse
1 Striped
marsh frog
6 June 2010
7 June 2010
8 June 2010
Page 24
Cane toads were recorded at all three culverts. Other fauna species recorded included Rough scaled snake,
Eastern water dragon, Garden skink, Tiger snake, Robust ctenotus and House mouse.
4.8 Frog Exclusion fences
The foot-based inspection of the road-side of exclusion fencing conducted on each morning of the pitfall survey
(April/May 2009, February and June 2010), did not indicate any native frogs. Additionally, no road killed frogs
were recorded during the monthly road kill surveys undertaken by the maintenance contractor. One cane toad
mortality was recorded north of culvert 1 during the summer monitoring period of 2010. It should be noted that
the method and detail of the road kill inspections may not be sufficient for the observation and identification of
potential frogs entering the alignment.
Evidence of deterioration in the frog exclusion fence was recorded in the vicinity of the frog culverts during the
2010 pitfall surveys, including separation of the horizontal fence panels (Rohweder, 2010). Effectiveness of the
fence as a barrier to frog movement was also compromised at Chainage 5250W, where it was observed that the
localized ground level was less than 400mm below the lip of the fence. This was rectified by digging out material
until the height of the frog fence met the design requirements of >400mm.
4.9 Population Status
Amphibian species recorded throughout the Tugun Bypass area during the entire period of monitoring included:

Cane Toad (Bufo marinus)

Desert tree frog (Litoria rubella)

Eastern dwarf sedge frog (Litoria fallax)

Eastern froglet (Crinia signifera)

Eastern sign-bearing froglet (Crinia parinsignifera)

Northern banjo frog (Lymnodynastes terrareginae)

Ornate burrowing frog (Lymnodynastes ornatus)

Peron’s tree frog (Lymnodynastes peronii)

Rocket Frog (Litoria nasuta)

Tyler’s tree frog (Litoria tyler)

Wallum froglet (Crinia tinnula)

Wallum sedge frog (Litoria olongburensis)
Page 25
The overall abundance recorded within both existing and compensatory frog ponds during construction and
operation is illustrated in Figure 7, and raw data is included as Appendix A.
Wallum froglet and Wallum sedge frog abundance varied throughout the monitoring period, with Wallum froglets
having a higher overall abundance than Wallum sedge frogs.
Both target species were recorded within or surrounding existing breeding ponds throughout construction and
operation, with a higher abundance recorded during summer than in autumn on most occasions. The monitoring
events which yielded the highest number of frogs in the existing ponds coincided with periods of high rainfall and
water level experienced in December/January 2008 and February 2010. The most recent frog monitoring event
(April 2011) yielded comparatively poor results for both species.
Wallum froglets were encountered less frequently in compensatory ponds than existing ponds, but still appeared
relatively abundant during construction. Similarly, Wallum Sedge frogs appeared to persist in the established
ponds throughout the monitoring period, while no observations of the species were recorded at the
compensatory ponds.
As discussed in section 4.1, it should be noted that after the commencement of operation (April 2008), frog
monitoring was undertaken seasonally rather than monthly.
Page 26
40
160
35
140
30
120
25
100
20
80
15
60
10
40
5
20
0
0
Rainfall (mm)
Abundance
Commencement of
Operation
Wallum sedge frog
Wallum froglet
Rainfall
Figure 7. Number of Wallum froglets and Wallum sedge frogs recorded at existing and compensatory habitats during monitoring events.
Page 27
5 DISCUSSION
5.1 Frog Ponds
In order to comply with performance criteria stipulated in Compensatory Habitat Package (Appendix H of the
Submissions Report), ponds were required to have a pH <5, electrical conductivity <350 µS/cm, contain surface
water for a period of >10 weeks per annum for at least two of the three year monitoring period and to be free of
pest fish species such as Mosquito fish.
5.1.1 Hydroperiod
Despite high weekly rainfall prior to surveys, compensatory pond C4 failed to retain a sufficient hydro-period
(measurable surface water for >10 weeks) during operational monitoring. After initial success, pond C2 ceased to
retain water for extended periods approximately 2.5 years after being constructed.
As a consequence of this, and in accordance with provisions of the Compensatory Habitat Package, the
fundamental design of compensatory ponds C2 and C4 was reviewed, their liners were checked and necessary
alterations were made in an attempt to increase the capacity for standing water, thereby improving suitability of
the ponds for breeding. These remediation actions were conducted in mid 2009 (SMEC, 2009).
Following this remedial action no significant improvement was observed in pond C4. Improvement was noted in
pond C2 although what proportion of this improvement was directly attributable to the remediation is difficult to
quantify as there has been increased rainfall in the area since that time.
The water levels consistently observed in ponds C1 and C3 were considered to be sufficient to enable successful
larval development (Rohweder, 2010).
5.1.2 Acidity/pH
Acidic aquatic environments such as Wallum habitat have a naturally low pH due to their low buffering capacity
and high concentrations of natural organic acids (Barth, et al 2010).
Fluctuations in pH across all sites appears to correspond with variations in temperature, such that the lower pH
values experienced during winter (i.e April 2009), steadily increased with increasing temperatures into summer
(i.e. February 2010). Occasional outlying variation in some values recorded within sites may be attributable to
errors in sampling equipment.
The pH ranges of the compensatory ponds exceeded the recommended values on most monitoring occasions,
suggesting that the size and elevation of the ponds are not sufficient to maintain the chemical processes
necessary to consistently achieve low pH (Rohweder, 2010). The size and “perched” nature of the ponds means
that they are heavily influenced by rainfall events which have the effect of raising pH levels.
Page 28
5.1.3 Electrical Conductivity
While the ponds displayed variable EC values, it appears that the stipulated performance criteria for pond C1, C2
and C4 are generally being met. The values of pond C3 were slightly elevated, exceeding the recommended
electrical conductivity of <350µS/cm on several occasions.
As expected, fluctuations in electrical conductivity appeared to coincide with water level and rainfall events
occurring prior to monitoring. Rainfall generally causes dilution of water, thereby reducing electrical conductivity,
while evaporation occurring in dryer periods makes surface waters more saline (high EC) (Abowei, 2009).
The difference in electrical conductivity levels evident between construction and operation may be attributable to
the use of recycled water, which generally has higher salinity levels, for artificial watering of the ponds during
construction. The establishment of aquatic and terrestrial vegetation within and surrounding ponds during
operation may have also had some influence on the organic matter and humic acids being received by the pond
surface water.
5.1.4 Pest Fish Species
Only one of the compensatory ponds (C3) was infested with Mosquito fish throughout construction and
operation. It is believed that colonization by the species may have been enabled when an adjoining drain
overtopped the pond following high rainfall in December 2008. Remediation action to remove the pest fish was
undertaken in 2009, and presence of the species has been recorded once (May 2010) since that time.
5.1.5 Frog usage
Whilst the presence of frogs was not a performance criterion for the ponds it should be noted that a diverse
range of amphibians including the Wallum froglet have been recorded from the compensatory ponds both during
and after construction. Wallum sedge frogs have not been recorded in the compensatory ponds during
operational monitoring (Rohweder, 2010).
Variation in the abundance of Wallum froglets observed between construction and operation is likely to be
attributable to the sampling frequency (monthly during construction, seasonally during operation), and the
occurrence of artificial watering of the ponds during construction. Additionally, it is possible that the frogs
observed in ponds throughout the early stages of construction may have been translocated with natural
vegetation during their installation in 2006 (Hero and Simpkins, 2008).
Page 29
The 2009 culvert survey provided encouraging data on the use of the culverts by Wallum frog species. Species
were recorded around the entrances of culverts 1 and 3, suggesting that movement between the east and west
side of the highway is likely to be occurring.
The subsequent 2010 monitoring event provided no additional information. It should be noted however, that
failure to record Wallum froglets during this survey is not an accurate reflection of the culverts’ suitability for
utilization by Wallum frogs. The result is likely to be attributed to unsuitable conditions for frog movement at the
time of monitoring, highlighting the complexity associated with frog surveys and their weather dependant nature
(Rohweder, 2009). While pitfall trapping was timed to coincide with rainfall events where possible, no adequate
rainfall occurred during the survey period to stimulate frog activity.
The presence of Wallum species at the culvert entrances provides some evidence that the exclusion fencing may
be acting to funnel frogs into the underpasses.
5.3 Frog Exclusion Fences
Specific active monthly searches for frogs along the road-side of the frog exclusion fences were not conducted
by the maintenance contractor throughout the monitoring period. While no frogs were identified in the daily road
kill inspections, this method was not considered suitable for assessing the effectiveness of the exclusion fences
as a barrier to frog movement, as road killed frogs are likely too small to be seen.
No road killed frogs were recorded in the foot based inspections conducted during pitfall surveys in 2009 and
2010, however, it was noted that these surveys may have been undertaken at times that were not conducive to
frog movement, such that the result may be attributable to lack of frog movement, rather than effectiveness of the
fencing as a barrier.
Additionally, the potential for the frog exclusion fencing to act as an effective barrier may have been
compromised by the presence of vegetation in front of the fence, which may act as a means for frogs to climb
over the barrier. The absence of a vegetation free zone creates a need for a more intensive maintenance regime
to uphold the fences effectiveness, which has proved difficult to achieve consistently since the Tugun Bypass
became operational.
Page 30
5.4 Population Status
A total of twelve (12) amphibian species were recorded at existing and compensatory ponds as well as at the
culverts throughout the entire period of monitoring. On average, Wallum froglets recorded a higher abundance
across all sites than Wallum sedge frogs. This variation in abundance is consistent with previous records (Lewis
and Goldingay, 2005), and may be a result of the overall wider distribution of Wallum froglets and the species’
ability to breed in disturbed habitat more readily than the Wallum sedge frog (Meyer et al. 2006).
Variation in the abundance of Wallum frogs at existing and compensatory habitats appears to reflect weather
conditions at the time of monitoring, such that maximum counts were recorded following high weekly rainfall
events during summer (January 2008 and February 2010). Conversely, the poor outcome yielded in spring 2009
is likely to be a result of prevailing dry weather, hindering Wallum frog calling activity. This variation is not
considered unusual (Lewis and Goldingay, 2005), rather, results emphasize the difficulty associated with frog
surveys and the weather dependant nature of their activity and movement.
Existing breeding habitat
Although only a small number of Wallum froglets were recorded at the compensatory ponds during monitoring,
the combined abundance of threatened frogs observed at both existing and compensatory habitats provides an
encouraging outcome regarding the population status. Water quality parameter results for the established
breeding ponds (Appendix A) also provide useful insight into the natural Wallum frog habitat conditions of the
area.
Results suggest that favourable water conditions have been maintained within the existing breeding ponds,
which have retained sufficient water throughout the duration of monitoring. Minimum pH values were within the
required range for successful reproduction of Wallum species, and EC values were relatively consistent,
remaining within the performance values stipulated for the compensatory ponds.
The frequency of calling males recorded in these areas indicates that reproduction is occurring and the
population appears to have remained stable (Rohweder, 2010). This means that there may be opportunities for
further colonisation into compensatory habitats.
Further to this there have been observations, both verified and anecdotal, of Wallum froglets calling from some of
the permanent bioretention basins established as part of the stormwater/water quality management system for
the Bypass. Whilst no formal monitoring of these areas has been undertaken (none was required under the
approvals) these observations suggest that the local population of Wallum froglets has not only persisted but
appears to be actively colonizing these basins.
Page 31
5.5 Monitoring Variability
With any monitoring of natural systems and wildlife populations variation caused by natural events can impact on
monitoring results. Over the 5 year monitoring period significant variation in climatic conditions occurred in the
study area. During construction (2006 -2007) SE Qld suffered one of the most severe sustained droughts ever
recorded. Towards the end of construction, and post construction, the drought lifted and higher than average
rainfall, including a number of significant flood events, has been recorded in the study area since that time.
Whilst this is likely to have had some impact on monitoring results the exact implications are difficult to quantify.
A number of scenarios are possible.

Drought conditions may result in frog populations falling overall;

Frog populations may become concentrated during drought events as marginal habitat areas dry out;
and

Frog populations may become more widely distributed in wetter conditions as marginal habitat areas
become usable (this may not initially mean there has been any increase in frog numbers).
These natural factors are unavoidable and the impact they have on monitoring results is only likely to be
definitively answered by extensive ecological research well beyond the scope of what is achievable within the
spatial and time limitations of the Tugun Bypass monitoring program.
Page 32
6 CONCLUSIONS
Frog monitoring associated with the Tugun Bypass project was required over a total of 5 years, three years of
which occurred post construction. Monitoring of the target Wallum frog species commenced during construction
(late 2006) and has continued regularly until mid 2011. The prevalence of calling frogs recorded throughout
construction and operation indicates that the local population is persisting, and the observation of sub-adult
Wallum sedge frogs in 2009 and 2010 provides evidence that this species has reproduced. From a purely
localized conservation perspective the project goal of maintaining Wallum frog habitat and existing populations
appears to have been successful. Breeding populations of the threatened target species have persisted and
remain present in and around the Bypass. On a wider perspective a significant area of Wallum frog habitat has
been secured as an offset and placed under formal conservation management. Conclusions specific to the
individual elements of the frog management program are outlined below
6.1 Compensatory ponds
The compensatory ponds have been moderately successful. Whilst they have met the performance criteria set
for them periodically, this fluctuated seemingly in accordance with responses to climatic events such as extended
periods of dry weather or significant rain events. Target species of frogs have made use of the ponds although
no evidence of the target species breeding in the ponds was found during monitoring.
The ponds have good potential to provide some conservation benefit in the future. Design refinement could
improve the performance of other similar ponds on future projects. However, given their reasonable level of
performance no benefit is seen in attempting to undertake significant works on the compensatory ponds beyond
normal maintenance.
6.2 Frog Exclusion Fences
The frog exclusion fence is an innovative idea and the extensive testing undertaken to come up with the ultimate
design of the exclusion fence showed that it would provide an effective barrier to frog movement. However, as
noted earlier it would appear that the absence of a vegetation free zone in front of the fence and ineffective
vegetation maintenance has reduced its effectiveness.
To what extent this effectiveness may have been compromised remains difficult to quantify given the challenges
inherent in monitoring frog fence performance. Monitoring frog road mortality (the element of the frog monitoring
program most likely to provide data relevant to exclusion fence effectiveness) on an active motorway at the time
of day and during weather conditions when frog movement is most likely to occur (i.e. at night, during wet
weather) requires specialist staff to undertake the work and is considered to be a high risk activity from an OH&S
perspective. Given the difficulties associated with conducting this type of survey, it is impractical to expect any
meaningful results to come from road mortality monitoring of such species.
Page 33
6.3
Frog Underpasses
Based on current monitoring results the frog underpasses appear to be used by a range of amphibians and other
species including the target Wallum frog species.
6.4 Compensatory habitat
The ability to secure and place under permanent conservation management, a significant area of Wallum frog
habitat is potentially the most positive fauna conservation outcome to be derived from the Tugun Bypass project.
The selection process used to secure this area of compensatory habitat was innovative and ultimately supplied
an excellent outcome.
6.5 Monitoring Program
The monitoring program was required to run for five years. This report provides a summary of those five years of
monitoring. All elements of the monitoring program have been undertaken in accordance with the requirements
of the relevant approval conditions.
6.6 Recommendations
The frog monitoring program has overall been a successful exercise. Whilst there have been mixed results in
some elements, overall there remains a healthy frog population and a number of the mitigation measures have
contributed to this result.
Key recommendations formed from the results of the monitoring are outlined below.
6.6.1 Compensatory Ponds
1. Compensatory ponds are an effective mitigation measure and should be considered for inclusion as part
of mitigation measures on future projects.
2. For future projects the design of compensatory frog ponds (targeted at Wallum frogs) to allow greater
interception of groundwater may have benefits for extending hydro period and improving water
chemistry for target species.
6.6.2 Frog Exclusion fence
1. In the case of the Tugun Bypass improved maintenance of vegetation adjacent to the frog exclusion
fence is required and standard operating procedures prescribed for maintenance need to be applied.
2. On future projects a permanently vegetation free zone in front of the frog exclusion fence should be
considered.
Page 34
6.6.3 Frog Underpasses
1. These frog movement structures should be considered for inclusion on future projects with similar fauna
habitat connectivity issues.
6.6.4 Compensatory Habitat
1. The use of a formal compensatory habitat selection study such as the one undertaken for the Tugun
Bypass should be undertaken on projects where the supply of compensatory habitat is required.
6.6.5 Monitoring Program
1. Monitoring of road frog mortality associated with active, operational roads should be discontinued and
not be considered for future projects as it is ineffective and represents an unacceptable OH&S risk to
the staff conducting the survey.
Page 35
7 REFERENCES
Abigroup Limited (2008). Operational Environmental Management Plan: PLA718 - Threatened Frog
Management, Report prepared for Pacific Link Alliance
Abowei, J.F.N. (2009) Salinity, Dissolved Oxygen, pH and Surface Water Temperature Conditions in Nkoro
River, Niger Delta, Nigeria. Advance Journal of Food Science and Technology 2 (1): 36-40
Australian Wetlands (2006). Wallum Sedge Frog (LItoria olongburensis) Wetland Habitat Translocation, Report
prepared for Pacific Link Alliance.
Barth. B. J, and Wilson. R. S. (2010). Life in acid: interactive effects of pH and natural organic acids on growth,
development and locomotive performance of larval striped marsh frogs (Limnodynastes peronii). Journal of
Experimental Biology, 213 (8): 1293-1300.
Bureau of Meteorology (BOM). (2011), Daily Weather Observations, Coolangatta (Station 040717), Queensland.
<http://www.bom.gov.au/climate/dwo/IDCJDW4036.latest.shtml>
DERM (2011). Wildlife and Ecosystems – Animals <http://www.derm.qld.gov.au/wildlifeecosystems/wildlife/az_of_animals/wallum_froglet.html>
Hero, J.M and Simpkins, C. (2008). Frog Monitoring during the first and final phase construction of the Tugun
Bypass (April 2006-November 2007). Centre for Innovative Conservation Strategies, Griffith University, Gold
Coast.
Hero, J.M., Phillips, S. And Shoo, L. (2001). Surveys of the Wallum Sedge Frog inhabitaing coastal lowland
areas associated with the proposed Tugun Bypass. Consultants report to QDMR.
Hopkins, M. C. (2003). Temporal and spatial distribution of breeding activity in an acid frog community at Tugun,
South East Queensland. Unpublished Honours Thesis, Griffith University. Gold Coast.
Ingram, G. And Caneris, A. (2005). Proposed Tugun Bypass. Review of Wallum Sedge Frog and Green-thighed
Frog, Biodiversity Assessment and Management (BAAM) Pty Ltd, Report prepared for Parsons Brinckerhoff
Australia Pty Ltd.
Lewis, B. D. and Goldingay, R. L. (2005). Population monitoring of the vulnerable Wallum sedge frog (Litoria
olongburensis) in north-eastern New South Wales. Australian Journal of Zoology, 53, 185-194
Page 36
Liem, D.S. and Ingram, G. J. (1977). Two new species of frogs (Anura: Myobatrachidae, Pelodryadidaoe) from
Queensland and New South Wales. Vic. Nat. 94: 255-262.
Meyer. E., Hero. J. M., Shoo. L. and Lewis. B. (2006). National recovery plan for the wallum sedge frog and other
wallum dependant frog species. Report to Department of the Environment and Water Resources, Canberra.
Queensland Parks and Wildlife Service, Brisbane.
Pacific Link Alliance (2010) Environmental Impact Audit Report: Operations, Report prepared for Department of
Transport and Main Roads (DTMR), NSW Roads and Traffic Authority (RTA).
Pacific Link Alliance, (2008) Operational Environmental Management Plan (OEMP)
PacificLink Alliance (2006). Frog Management Plan for the Tugun Bypass, Report prepared for Department of
Transport and Main Roads (DTMR)
Renwick, J. (2006). Population structure and genetic diversity of south east Queensland populations of the
Wallum froglet, Crinnia tinnula (Tschudi). School of Natural Resource Sciences, QUT, Brisbane, Australia.
Rohweder, D. (2009) Tugun Bypass Frog Monitoring Report, Summer and Autumn 2008/2009. Sandpiper
Ecological Surveys, Alstonville, NSW.
Rohweder, D. (2010) Tugun Bypass Frog Monitoring Report, Summer and Autumn 2010. Sandpiper Ecological
Surveys, Alstonville, NSW.
SMEC Australia Pty Ltd (2009) Tugun Bypass Compensatory Habitat Package – Outstanding Offsets: Final
Report. Report prepared for Department of Transport and Main Roads.
The State of Queensland (Department of Environment and Resource Management) 2011. Wildlife and
Ecosystems, <http://www.derm.qld.gov.au/wildlife-ecosystems/wildlife/az_of_animals > accessed 16/09/11
Tugun Bypass Alliance (2004), Species Impact Statement (SIS) and Equivalent Studies under Relevant
Queensland and Commonwealth Legislation, Report prepared for Department of Transport and Main Roads
Tugun Bypass Alliance (2004), Tugun Bypass Environmental Impact Statement (EIS) and associated Technical
Papers. Report prepared for Department of Transport and Main Roads
Page 37
APPENDIX A – RAW DATA
Table 1. Frog calls in existing (M3, M4b, M5, M6 and D1) and compensatory (C1, C2, C3, C4) breeding habitats
Monitoring
Location ->
Species ->
6-Apr-06
22-May-06
26-Jul-06
23-Aug-06
20-Sep-06
18-Oct-06
12-Dec-06
24-Jan-07
15-Feb-07
14-Mar-07
18-Apr-07
9-May-07
6-Jul-07
25-Jul-07
27-Aug-07
10-Oct-07
31-Oct-07
5-Dec-07
15-Jan-08
6-Feb-08
12-Mar-08
15-Apr-08
3-Dec-08
10-Dec-08
6-Apr-09
28-Apr-09
M3
M4b
M5
M6
D1
WF
WS
WF
WS
WF
WS
WF
WS
1
1
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
7
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
5
0
8
0
1
0
4
1
4
3
1
0
6
0
5
0
2
8
11
2
2
8
0
0
0
0
3
0
2
1
0
0
0
0
0
0
0
0
0
0
7
2
0
0
3
2
5
0
6
0
3
0
0
0
0
3
0
0
0
0
0
0
1
0
0
0
0
0
0
0
2
6
4
4
7
0
4
2
3
0
1
0
0
3
1
1
4
0
0
0
3
2
0
2
0
0
0
0
P
4
0
0
0
0
0
0
1
0
1
0
1
0
0
0
0
2
4
0
0
1
>10
>10
3
1
4
1
5
3
3
4
8
0
0
4
1
0
6
0
0
0
5
4
0
1
WF
0
0
4
1
2
4
0
1
0
0
0
0
2
0
C1
WS
0
0
1
6
2
9
0
0
0
0
1
2
0
0
C2
C3
C4
WF
WS
WF
WS
WF
WS
WF
WS
1
0
0
0
3
0
0
1
3
1
4
3
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
1
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
1
3
1
0
3
0
2
1
1
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
2
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
Page 38
Monitoring
Location ->
11-Feb-10
18-Feb-10
4-May-10
6-May-10
13-Apr-11
14-Apr-11
M3
3
2
2
2
2
1
M4b
2
4
0
0
0
0
4
7
7
5
2
0
M5
1
0
0
0
0
1
18
13
11
9
2
0
M6
7
4
2
0
0
1
5
11
8
2
1
0
D1
2
1
1
0
0
0
1
1
0
1
0
0
C1
0
1
0
0
0
0
0
0
0
0
0
1
C2
0
0
0
0
0
0
0
0
0
0
0
0
C3
0
0
0
0
0
0
0
1
0
0
0
0
C4
0
0
0
0
0
0
0
0
0
0
0
0
WF: Wallum froglet
WS: Wallum sedge frog
Page 39
0
0
0
0
0
0
Table 2. Surface Water level (m) at existing and compensatory habitats
Monitoring
location ->
M5
M6
C1
C2
C3
C4
0
0
0
22-May-06
0.15
0.2
0.1
26-Jul-06
0.6
0.2
0.78
0.3
23-Aug-06
0.08
0
0
0
20-Sep-06
0.4
0
0.4
0.4
0.3
0
0.15
0.1
18-Oct-06
0
0
0.1
0
0.05
0
12-Dec-06
0
0
0.2
0
0.2
0.05
24-Jan-07
0
0
0
0
0
0
15-Feb-07
0.02
0
0.25
0
0.1
0
14-Mar-07
0.2
0.15
0.1
0.05
0.1
0
18-Apr-07
0
0
0
0
0.1
0
9-May-07
0
0
6-Apr-06
M3
M4b
D1
0
0
0.13
0
0.26
0.1
0.25
0
0.1
0.08
0
0.2
0
0.32
0.31
0.13
0.38
0
0.25
0.15
0.3
0
0.2
0
0.19
0
6-Jul-07
25-Jul-07
27-Aug-07
0.37
0
0.18
0.3
10-Oct-07
0.24
0
0
0.3
31-Oct-07
0.11
0
0.075
5-Dec-07
0.1
0
0.1
0.15
0.03
0
0
15-Jan-08
0.4
0.77
0.53
0.37
0.1
0.28
0
6-Feb-08
0.43
0.75
0.66
0.44
0.16
0.39
0.13
12-Mar-08
0.09
0.6
0.19
0.22
0
0.13
0
0.045
0.14
Page 40
15-Apr-08
0.274
3-Dec-08
0.4
10-Dec-08
6-Apr-09
28-Apr-09
0.545
0.15
0.225
0.01
0.12
0
0.6
0.59
0.17
0.13
0.24
0
0.26
0
0.36
0.55
0.54
0.17
0.22
0.29
0
0.22
0
0.42
0.66
0.33
0.58
0.69
0.25
0.36
0.41
0.09
0.41
0
0.39
0.13
0.18
0.32
0
0.26
0
11-Feb-10
0.38
0.41
0.62
0.22
0.06
0.17
0
0.2
0
18-Feb-10
0.28
0.39
0.57
0.21
0.35
0.19
0.02
0.23
0
4-May-10
0.43
0.63
0.4
0.21
0.75
0.33
0.09
0.38
0.34
6-May-10
0.44
0.58
0.53
0.23
0.1
0.24
0
0.21
0.09
0.45
0.25
0.13
0.1
0.4
0.4
0
0.09
0
0.15
0.12
0.3
0.3
13-Apr-11
14-Apr-11
0.25
0.05
0.65
0.42
0
Page 41
Figure 1. Surface water levels in existing breeding ponds over time
Page 42
Table 3. pH in existing and compensatory breeding habitats
Monitoring
location ->
M3
22-May-06
26-Jul-06
23-Aug-06
4.75
20-Sep-06
4.71
M4b
M5
M6
4.93
4.3
4.82
3.48
3.04
3.41
4.69
4.18
D1
C1
C2
C3
C4
5.94
7.41
4.87
5.56
18-Oct-06
7.3
5.4
12-Dec-06
6.83
6.18
24-Jan-07
5
4
15-Feb-07
6.07
5.2
14-Mar-07
4.55
4.4
6.57
6.47
4.91
18-Apr-07
7.54
9-May-07
6.35
25-Jul-07
5.15
5.2
6.27
5.45
6.43
6.43
6.07
4.47
27-Aug-07
6.35
7.24
5.99
31-Oct-07
5.6
4.87
5.03
5.88
5-Dec-07
7.31
5.63
5.71
5.97
5.86
15-Jan-08
5.83
4.76
4.69
4.89
5.76
6.17
6-Feb-08
5.49
5.61
5.12
5.39
5.44
5.78
12-Mar-08
5.3
4.91
4.81
5.42
5.87
6.15
3-Dec-08
4.81
4.78
4.63
4.69
4.61
5.28
5.81
10-Dec-08
5.56
5.04
5.13
5.3
5.02
5.32
5.38
6-Apr-09
5.1
4.8
5.12
4.94
4.84
4.61
28-Apr-09
3.75
2.94
3.14
3.41
3.41
4.48
5.18
11-Feb-10
4.19
5.06
4.18
4.17
5.92
5.58
5.8
18-Feb-10
4.7
5.02
4.75
4.45
5.83
5.76
6.09
5.96
4-May-10
4.9
5.55
4.56
5.02
5.06
5.99
4.99
5.66
5.64
6-May-10
4.51
5.7
4.92
4.8
5.7
5.27
5.65
5.79
13-Apr-11
6.18
14-Apr-11
5.29
8
6.5
4.7
4.91
4.6
4.9
5.39
6.5
6.44
5.2
6.12
7.33
5.94
5.52
4.38
5.8
6.3
4.16
4.42
Page 43
Figure 2. pH in existing breeding ponds over time
Page 44
Table 4. Electrical Conductivity in existing and compensatory breeding habitats (µS/cm)
Monitoring
location ->
M3
22-May-06
26-Jul-06
M4b
M5
M6
35
110
168
32
117
42
D1
C1
C2
C3
C4
380
20-Sep-06
461
382
18-Oct-06
1450
195
12-Dec-06
598
174
15-Feb-07
14-Mar-07
564
75
114
438
2
772
518
18-Apr-07
778
9-May-07
359
31-Oct-07
112.8
153.4
415.8
445.3
5-Dec-07
0.5
1126.5
150.7
286.5
100.5
447.1
15-Jan-08
104.9
72.8
58.2
80.2
118.1
138
262.9
6-Feb-08
72.8
100.3
51.4
70.3
94.5
83.6
356.3
10-Mar-08
101.8
119.1
109
136.3
281.7
592.1
232.1
987.3
6-Apr-09
387
203.7
23.6
39.7
32.7
29.5
28-Apr-09
239
243
73.5
91.3
70.3
43.4
336
11-Feb-10
245.9
362.8
143.6
114.5
171.5
154.8
731.9
18-Feb-10
112.3
287.3
169.6
233.7
172.5
190.2
144.1
427.5
4-May-10
54.4
83.7
37.6
24.9
53.4
583
106.9
460.7
55.6
6-May-10
118.5
135.7
67.1
72.7
99.1
545.6
74
98.3
13-Apr-11
29
12
72
67
82
19
83
51
100
14-Apr-11
156
129
57
0
121
79
54.5
385
Page 45
Figure 3. Electrical Conductivity in Existing breeding over time
Page 46
APPENDIX B – PHOTOS
1. Construction of Compensatory Frog ponds
2. Construction of Compensatory Frog ponds
Page 47
3. Construction of Compensatory Ponds
4. Construction of Compensatory Ponds
Page 48
5. Installation of water level control device
6. Water level control device in use
Page 49
7. Frog Fence – Recycled wood + Galvanised metal flashing
8. Frog Fence - Insertion rubber bound to existing boundary fence
Page 50
9. Monitoring of existing habitats
10. Monitoring of existing habitats
Page 51
11. Wallum Sedgefrog (LItoria olongburensis)
12. Wallum Froglet (Crinia tinula)
Page 52
APPENDIX C – COMPENSATORY HABITAT SELECTION
Page 53
APPENDIX D – DESIGN DRAWINGS
Page 54

Frog Management Plan - Department of Transport and Main Roads

Transcription

Similar documents

it now, click here

“AN INITIATIVE TOWARDS “SOCIAL RESPONSIBILITY”

the brochure

Web-Based Context-Aware Science Learning

circus - Frog Street

Home Range and Movement Patterns of the Otton Frog

The discovery of the blue arrow poison frog, Dendrobates azureus in

Everything you need to know about frogs and other slippery

The Complexity of Crazy Frog Puzzle and Permutation