Baseline aquatic assessment of wetlands identified for feral pig fence ...

Baseline aquatic assessment of wetlands identified for feral pig fence exclusion, Archer River catchment Nathan Waltham, Jason Schaffer Report No. 15/41 March 2016

Baseline aquatic assessment of wetlands identified for feral pig fence exclusion, Archer River catchment A Report for Balkanu Cape York Development Corporation Pty Ltd Report No. 15/41 March 2016

Prepared by Nathan Waltham and Jason Schaffer

Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) James Cook University Townsville Phone : (07) 4781 4262 Email: [email protected] Web: www.jcu.edu.au/tropwater/

Information should be cited as: Waltham, NJ, Schaffer, J 2015, ‘Baseline aquatic assessment of wetlands identified for feral pig fence exclusion, Archer River catchment’, Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) Publication, James Cook University, Cairns, 51 pp.

For further information contact: Dr Nathan Waltham Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) James Cook University Email address – [email protected] Phone number – 0411 161 161

This publication has been compiled by the Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), James Cook University. © James Cook University, 2016. Except as permitted by the Copyright Act 1968, no part of the work may in any form or by any electronic, mechanical, photocopying, recording, or any other means be reproduced, stored in a retrieval system or be broadcast or transmitted without the prior written permission of TropWATER. The information contained herein is subject to change without notice. The copyright owner shall not be liable for technical or other errors or omissions contained herein. The reader/user accepts all risks and responsibility for losses, damages, costs and other consequences resulting directly or indirectly from using this information. Enquiries about reproduction, including downloading or printing the web version, should be directed to Dr Nathan Waltham – [email protected]

Acknowledgments: The authors thank Balkanu Cape York Development Corporation, and staff and rangers from the APN Cape York (Aak Puul Ngantam), Southern Wik Homelands station for access to Country.

Baseline wetland assessment – feral pig fence exclusion (Archer River) – TropWATER Report 15/41

EXECUTIVE SUMMARY The introduction of feral pigs (Sus scrofa) in northern Australia has contributed to wide scale negative impacts on coastal wetland vegetation assemblages, water quality, biological communities and wider ecological impacts. The challenge for managers faced with managing wetland ecosystems from feral pigs is access to explicit data and information to assist on-ground restoration efforts. Plans to manage wetlands in the Archer River catchment (western Cape York) from continuing feral pig impact initiated the need to compile a baseline wetland dataset. During a short field survey (25 to 29th June 2015) five wetlands located on the lower Archer River floodplain were surveyed for a range of limnological measures. These five wetlands have been identified as part of a future pig exclusion fencing campaign. Unlike other fencing programs that completely enclose a wetland, here wetlands will be fenced through the centre and effectively enclosing half the wetland from access by feral pigs, with the remaining half of the wetland open to access. All wetlands (inside and outside proposed fencing areas) were examined for water quality, fish, macroinvertebrates and freshwater turtle diversity. In addition to the five wetlands on the Archer River floodplain, two wetlands were examined using these same methodologies, adjacent to Peach Creek (Kalan wetlands) in the upper region of the Archer River catchment. These Kalan wetlands have current fence exclusion measures in place (constructed approximately 12 months ago). The first Kalan wetland has been fenced entirely using a 100 x 100mm square mesh panel to exclude feral pigs and cattle, while the second Kalan wetland has three string barb wire fencing enclosure, which excludes cattle, but allows feral pigs access. The salient points in the results include:  Water quality cycling measured in the wetlands was expected, however, there were some differences in the maximum and minimum water conditions, with the Kalan wetland with cattle fencing only experiencing the poorest water conditions, with critically low dissolved oxygen, and elevated turbidity conditions, that would be harmful to aquatic fauna;  Fish community across the wetlands generally represented a sub-set of the freshwater fish assemblage reported in the Archer River channel. This reduced assemblage might be a consequence of poor habitat conditions in the wetlands, limitations in the sampling methods, or the fact that antecedent flow in the wet season prior to this survey was low, within the lower percentile of long term rainfall records for the region;  Macroinvertebrate assemblage generally supported species representing relatively good water quality conditions, though differences in the assemblage existed among wetlands presumably owing to local environmental and habitat differences;  Three of the five freshwater turtle species known from the Archer River catchment were identified here. It was interesting that all the turtles captured in the floodplain wetlands were adults, while in the Kalan pig exclusion wetland only juvenile individuals were captured – suggesting that the enclosures themselves may have the potential to negatively isolate freshwater turtles, raising the concern that current fencing practices might be inappropriate. These data provide a preliminary look at wetlands continually impacted by feral pigs in the Archer River catchment. While little differences existed in the conditions measured ‘inside’ and ‘outside’ proposed fencing ends of each wetland, it is expected that differences will become more apparent following construction of fences, as wetland conditions respond to the mitigation efforts. The study highlights the need to test the efficacy of fencing designs, to ensure that the design achieves the dual benefits of excluding access to wetlands by target feral species, but also still permits aquatic animals to migrate between wetlands and river channels. Such information would be useful to successfully direct future wetland protection efforts against feral pig impacts in northern Australia. Page 4


TABLE OF CONTENTS EXECUTIVE SUMMARY .................................................................................................................. 4 1 INTRODUCTION .......................................................................................................................... 6 1.1 Coastal wetlands – feral pig impacts ........................................................................................ 6 1.2 Pig exclusion strategies ............................................................................................................ 7 1.3 Archer River ............................................................................................................................ 7 1.3.1 Rainfall and flow .......................................................................................................... 8 1.4 Project aims ........................................................................................................................... 10 2 METHODOLOGY ....................................................................................................................... 10 2.1 Wetland sites.......................................................................................................................... 10 2.2 Ambient water quality ........................................................................................................... 12 2.2.1 Water column cycling .............................................................................................. 12 2.2.2 Pug marks - water temperature logging ................................................................... 13 2.3 Aquatic communities ........................................................................................................ 13 2.3.1 Aquatic macroinvertebrates ..................................................................................... 13 2.3.2 Fish assemblage........................................................................................................ 13 2.3.3 Freshwater turtles.................................................................................................... 14 2.4 Data analysis .......................................................................................................................... 15 3 RESULTS ..................................................................................................................................... 16 3.1 Water quality ......................................................................................................................... 16 3.1.1 Ambient water quality ............................................................................................. 16 3.1.2 Pug marks – water temperature loggers .................................................................. 19 3.2 Aquatic fauna ........................................................................................................................ 20 3.2.1 Aquatic macroinvertebrates .................................................................................... 20 3.2.2 Fish assemblage ....................................................................................................... 24 3.2.3 Baited fish traps....................................................................................................... 27 3.2.4 Freshwater turtles.................................................................................................... 28 4 DISCUSSION and conclusions ...................................................................................................... 31 4.1 4.2 4.3 4.4

Wetland water quality ........................................................................................................... 31 Aquatic fauna ........................................................................................................................ 32 Aquatic wetland plants .......................................................................................................... 41 Continuing research and monitoring of wetland management ............................................... 43

5 REFERENCES ............................................................................................................................. 45 A APPENDICES .............................................................................................................................. 48 A.1 Freshwater fish counts using baited underwater video cameras (BRUVs) ............................. 48 A.2 Aquatic macroinvertebrates .................................................................................... 49 A.3 Freshwater turtles................................................................................................... 50

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1

INTRODUCTION

1.1

Coastal wetlands – feral pig impacts

Coastal wetlands provide critical habitat for aquatic flora and fauna species, and cultural values for local communities in northern Australia. The ability for wetlands, however, to continue providing these same ecosystem services in the future is threatened owing to a range of pressures such as agriculture, overfishing, hunting, recreation, water extraction and pollution of water. In addition to these, and increasingly so, are the introduction of feral animals which while also provide a use for humans in some instances (i.e., food substance), introduced populations can easily increase and contribute to wide scale destruction and long term consequences, including loss of sensitive species and habitat including coastal wetlands. Across northern Australia, the introduction of feral pigs (Sus scrofa) has contributed to wide scale negative impacts on wetland vegetation assemblages, water quality, biological communities and wider ecological processes (Figure 1.1). Feral pigs have an omnivorous diet (Baber and Coblez 1987) sourced by foraging or digging the roots, bulbs and other below ground vegetation material over terrestrial or wetland areas. This feeding strategy contributes to wide scale loss of vegetation. The loss of this vegetation contributes to exposure of soils to erosion and in the case of wetlands, feral pigs can turn over wetland benthic sediments, resuspending sediment and nutrients, and generally contributing to dramatic water quality affects such as reduced water clarity and eutrophication. Limited specific data is available on the impact that feral pigs contribute to coastal wetlands (Doupe et al., 2009), which confines the ability for land managers to appropriately measure the true consequences of feral pig destruction, but more importantly to track the success following expensive mitigation efforts. Figure 1.1

Connecting wetland areas on the Archer River floodplain following feral pig activity (photo taken June 2015)

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1.2

Pig exclusion strategies

Strategies to reduce or to totally remove feral pigs have been employed since their introduction to Australia. A range of strategies are available including poison baiting, aerial shooting, and trapping using specially constructed mesh cages. Attempts to exclude feral pigs directly from accessing sensitive wetlands have also relied on constructing exclusion fencing that border the entire wetland of interest. While the advantages of installing fencing around wetlands has only really been examined recently in Australia (see Doupe et al., 2009), the results suggest that wetland fencing might well be less effective in situations where wetlands would normally dry during the dry season. Fencing is expensive to construct and maintain, but at the same time are also effective in preventing other nontarget terrestrial fauna, such as kangaroos, from accessing the wetlands. (Other terrestrial species including birds, snakes and lizards, for example, are still generally able to access wetlands).

1.3

Archer River

The Archer River catchment is situated in Cape York Peninsula, northern Queensland (Figure 1.2). The head waters of the river rise in the McIlwraith range on the eastern side Cape York, where it flows west entering Archer Bay on the western side of the Gulf of Carpentaria; along with the Watson and Ward Rivers. The catchment area is approximately 13,820 km2, which includes approximately 4% (510 km2) of wetland habitats, such as estuarine mangroves, salt flats and saltmarshes, wet heath swamps, floodplain grass sedge, herb and tree Melaleuca spp. swamps and riverine habitat. The lower region of the catchment includes part of the Directory of Internationally Important Wetland network that extends along much of the eastern Gulf of Carpentaria, including the Archer Bay Aggregation, Northeast Karumba Plain Aggregation and Northern Holroyd Plain Aggregation. Two national parks are located in the catchment (KULLA (McIlwraith Range) National Park, and Oyala Thumotang National Park). Land use in the catchment is predominately grazing.

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Figure 1.2

A) Location map of Archer River catchment in northern Queensland; B) River catchment; and C) extent of conservation and protected areas in the catchment, and wetlands examined in this study (red circles) B)

A)

Archer River catchment

C)

Directory Important Wetlands Nature refuges Register of National Estate

1.3.1

Rainfall and flow

Rainfall has been recorded daily at the Aurukun Council station since 1915. Analysis of this time series data set (Figure 1.3) reveals that the highest wet season rainfall occurred during 1989/1999 (2515 mm), while the lowest was 1960/1961 (563.5 mm) (Table 1.1). Total antecedent rainfall for wet season (Nov 2014 to Feb 2015) prior to this survey totalled 1081 mm, which is below the 10th percentile for historical records. The years prior to the 2014/2015 wet season (2010 to 2014), were among the wettest season on record, within the 95th percentile of the distribution. The lower than average rainfall prior to this field survey is an important consideration in the data collected during this baseline investigation, in that it probably contributed to a shorter than expected flood plain duration, and connection between the wetlands surveyed and the main Archer River.

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Figure 1.3

BOM wet-season (Nov-Feb) rainfall data recorded at Aurukun Council (station number 27000) ranked in order of decreasing total rainfall (mm). Blue bars show total rainfall over the past few years, red bar cover wet season prior to this survey

Wet season rainfall (mm) 0

500

1000

1500

2000

2500

3000

2010-2011 2013-2014

Aurukun wet season rainfall (mm) 1914- 2015 sorted by wet season total

2011-2012

2014-2015

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Table 1.1

Summary wet season (Nov – Feb) statistics of rainfall recorded at Aurukun Council station

Statistic Minimum Maximum Mean Median 90th percentile 10th percentile 2014/15 wet season total

1.4

Wet season rainfall (mm) 563.5 (1960/1961) 2515 (1989/1999) 1667.4 1651.9 2222.4 1113.2 1081

Project aims

The aims of this project were threefold: 1) Undertake a baseline survey of aquatic fauna occupying wetlands identified for feral pig fencing; 2) Begin to establish a framework to assess wetland habitat condition to future comparison to examine fencing success; and 3) Share knowledge and commence preliminary training of APN Land and Sea Rangers in wetland monitoring and management.

2

METHODOLOGY

2.1

Wetland sites

Seven wetlands were selected in this investigation; five palustrine systems located adjacent to the Archer River on the APN station, with a further two Kalan wetlands located adjacent to Peach Creek (Figure 2.1), which were fenced approximately 12mths prior to this survey (K1 – fenced consisting of a 100 mm2 mesh panel designed to exclude access by pigs and cattle; and K2 – fenced using three strain barb wire designed to exclude cattle only, with pigs able to access the wetland). This survey was completed between 26 June and 2 July 2015. Wetland sites were determined after consultation with personnel from CSIRO Tropical Landscape Joint Venture, Townsville. The location of the five off channel wetlands were identified as part of a proposed feral pig fencing project funded under Australian Government Biodiversity Funding. The intention is to fence these wetlands approximately through the centre and then around one half of each wetland. This will effectively leave the remaining half of the wetland open to access by feral pigs, but also other native terrestrial fauna in the region (e.g., kangaroos). To the best of knowledge, this is the first time that fencing mitigation efforts have considered this style of intervention, as opposed to the more common approach where an entire wetland is fenced, precluding access entirely too feral pigs, but also other terrestrial fauna. Here the long term plan is to examine whether the wetland ecosystem services can be achieved at a reduced initial and ongoing maintenance cost with only fencing half a wetland. For each wetland, a polygon was first drawn around half of each wetland using GIS, which was then used to determine the sampling program. For each wetland, two (nested) replicate sites were included, defined as “inside” the fenced portion of the wetland, and “outside” the proposed fencing area (Figure 2.2). At each replicate wetland site, paired measurements were completed including water quality, macroinvertebrate, and fish community. A summary of the site locations is provided in Table 2.1. Page 10


Figure 2.1

Location map of wetlands included in this baseline survey

Figure 2.2

Illustration of proposed fencing half the wetland (red line), with survey sites ‘inside’ and ‘outside’ of proposed fencing enclosure

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Table 2.1

Summary details for sampling locations Wetland

Location

Latitude

Longitude

AR 2

Inside Outside Inside Outside Inside Outside Inside Outside Inside Outside Pig/cattle exclusion Cattle exclusion only

-13.577350° -13.574910° -13.603880° -13.603095° -13.626415° -13.625340° -13.638440° -13.639610° -13.771950° -13.769990° -13.678800° -13.679900°

141.676900° 141.677400° 141.683270° 141.681918° 141.696289° 141.696960° 141.707760° 141.709295° 141.889690° 141.890640° 143.141100° 143.140440 °

AR 3 AR 4 AR 5 AR 6 K1 K2

2.2

Ambient water quality

2.2.1 Water column cycling A calibrated Hydrolab multi-probe data logger was deployed in the near-surface water layer (0.2m below the surface, both inside and outside proposed fenced areas) to measure diel periodicity (cycling) of these physicochemical parameters at 20 min intervals. Loggers were deployed between 24hrs and 72hrs (Table 2.2). After the logging period, loggers were moved to the next wetland, and again deployed following the methodology outlined. Unfortunately, two hydrolab loggers failed to initiate logging which resulted in no data collected at AR2_Inside, AR4_Outside, AR5_Outside, AR6_Inside and K1 pig and cattle exclusion wetland. Table 2.2

Summary deployment details for hydrolabs for wetlands surveyed. Orange highlighted rows indicate where loggers failed to initiate Start Month

Start Day

Start Hour

Start Min

End MM

End Day

End Hour

End Min

AR2_Outside

6

24

16

30

6

25

16

15

24/06/15 16:30 25/06/15 16:15

AR3_Inside

6

24

17

50

6

26

17

10

24/06/15 17:50 26/06/15 17:10

AR3_Outside

6

24

19

0

6

26

17

20

24/06/15 19:00 26/06/15 17:20

AR4_Outside

6

26

19

0

6

28

10

30

26/06/15 19:00 28/06/15 10:30

AR5_Inside

6

27

8

45

6

29

8

0

27/06/15 08:45 29/06/15 08:00

6

28

9

30

6

29

10

10

28/06/15 09:30 29/06/15 10:10

6

29

19

20

7

1

7

30

29/06/15 19:20 01/07/15 07:30

Site

Start Time

Finish Time

AR2_Inside

AR4_Inside

AR5_Outside AR6_Inside AR6_Outside K1_Pig K2_Cattle

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2.2.2 Pug marks - water temperature logging Water temperature cycling in pug markings found surrounding wetlands following pig activities were examined by deploying Hobo temperature loggers (Onset Corporation) inside pug marks (Figure 2.3), and also in the wetland water column adjacent to pug marks. The pug marks ranged in size from 0.3 to 0.8m length, 0.15 and 0.3m width, and 0.1 to 0.25m depth. All loggers were programmed to record data every 20 min, with the logging period for the pug marks commencing 12:00am 26 June 2015, with the loggers retrieved 10:40am 28 June 2015. Figure 2.3

Pug mark with continuous water temperature logger with pink surveyor tape

2.3

Aquatic communities

2.3.1

Aquatic macroinvertebrates

Aquatic invertebrate communities were sampled at each wetland (inside and outside proposed fencing) using a standard dip net (triangular frame: 0.3m x 0.3m x 0.3m, 0.65m bag depth, mesh size 250μm). Kick samples of benthic habitat (wetland bottom substrate) were collected at all sites (over an area of 2m2). In addition, macrophyte samples were collected by sweeping the dip net through and along vegetation over an area of approximately 2m2. On site live picking of aquatic invertebrates was conducted for 45min in total per habitat type (15min for each of the three replicates per habitat). Specimens were stored in vials and preserved in 70% ethanol before laboratory processing. 2.3.2

Fish assemblage

Freshwater fish community were examined using a combination of methods in order to maximise the probability of recording any species that could possibly be present in waterholes. The details of each sampling method is outlined in Table 2.3.

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Table 2.3

Equipment, methods and effort to examine aquatic community in waterholes

Equipment Baited traps

Method

Effort



 

Baited pots, soak time of 2hrs Opera house, soak time of 12hrs (overnight)



Electrical conductivity too low to effectively use this method



Approximately waterhole

 Back pack electrofishing

Visual survey





0.4x0.2x0.2m pots, 100g aquaculture pellets Round opera house baited trap with canned tuna Sweeping a bank stretch of approximately 100m through all different habitat types (open areas, vegetation, debris) Walking bank and during field work in wetland

4hrs

per

Overall, the final techniques used were baited traps, visual survey and under water cameras. The efficacy of the back pack electrofisher was surprisingly compromised, as the electrical conductivity was too low in all wetlands rendering it ineffective. At each wetlands site (inside and outside) between two and three BRUVs (GoPro Hero 3, San Mateo, CA, USA) attached to custom frames and baited with canned sardines in vegetable oil were deployed per assigned side (inside or outside) at ~150m intervals in approximately 0.5m of water within and along the outside margins of the riparian forest fringe for a total of 5-6 BRUVs/wetland site. It was anticipated that this positioning would optimise the detection of species, especially highly mobile top-level predators which typically inhabit deeper water towards the centre of the wetlands. Species identity, MaxN and time of first appearance on camera were recorded by reviewing a total of 60 mins of footage/replicate in VLC Media Player (version 2.0.4; VideoLAN, Paris, France). Footage was viewed in real time corresponding to the first 10 min after deployment and then viewed in fast forward or real time depending on ease of viewing (e.g., diversity of species in view, clarity of water and glare). Footage was paused to allow precise quantification of abundance. We calculated replicate-level species richness, species specific MaxN and mean arrival time of each species to the BRUVS.

2.3.3 Freshwater turtles Freshwater turtle community were examined at one site on the Archer River and 6 adjacent off channel wetland sites using specialised circular (820 mm ×2500 mm) collapsible ‘cathedral-style’ turtle trap (see Hamann et al. 2008) (Figure 2.5), baited with standardised canned sardines in vegetable oil. Two traps were (both inside and outside proposed fencing) deployed which were spaced ~150m a part set in ~1.5m of water. Two traps set in the Archer River were hung from woody debris alongside the river bank in 1-2m of water ~200m apart. Traps were set in the mid to late afternoon (1500 – 1700 hours) and checked between 1000 and 1200 hours the following day. Traps were therefore open and undisturbed overnight, which in our experience is the most productive time to capture freshwater turtles. All captured individuals were weighed (except individuals caught in the Kalan Wetland pig exclusion site K1), measured, tissue sampled for future analysis and released back at the site of capture. All Emydura sp. individuals captured during the course of the surveys had the pictures taken of the inside roof of the mouth in order to accurately differentiate species as per Thomson (2003). Baited traps were also deployed in pig exclusion fenced and unfenced Kalan wetlands (adjacent to Peach Creek; see Figure 2.1). Traps set in the fenced wetland were deployed in the late afternoon Page 14


and checked the next morning approximately 0900. Low water levels and a lack of suitable attachment vegetation in the unfenced wetland (K2) meant that traps could not be extended upwards to allow captured turtles to access the surface to breathe and were instead set free-standing without external attachment and checked hourly to remove captured individuals in order to avoid drowning (traps were only deployed for 1 hour/trap and were not left overnight). Figure 2.5

Typical deployment of a “Cathedral” trap. Note extended upper section with floats elevated above water line to facilitate surface access

2.4

Data analysis

A range of summary and community assemblage statistics have been used in this report. Each are described in more details in the relevant section.

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3

RESULTS

3.1

Water quality

3.1.1 Ambient water quality Water temperature data is an essential interpretative aid for ecological assessment in environments of this sort which can naturally experience maxima and minima that are extreme enough to be acutely harmful to biota, such as freshwater fish, turtles and macroinvertebrates. Water temperatures during the current reporting period (mid-winter) were generally about 26oC (Table 3.1), which is close to the mean temperature of regional rivers (Butler and Burrows 2012). (For the maximum values recorded approaching 28oC are generally considered to be optimal for local aquatic species). Minimum water temperature recordings as low as 18oC are approaching which could contribute to bacterial infections, which have been recorded in freshwater fish in southern Gulf catchments were water temperatures reach almost 10oC (Waltham and Butler 2014). The electrical conductivity (EC) was very low (Figure 3.1, Table 3.1), much lower than data collected in other rivers in southern Gulf catchments (Waltham et al., 2013). The contribution of groundwater inflows is unknown in this region, but could be determined using radio isotope tracing methods (Jolly et al., 2013). There was some evidence of the cyclical daily DO fluctuations that are commonly observed at these kinds of sites, supporting the contention that biological processes were probably not significantly inhibited at the time of sampling. Nevertheless, daily minimum DO concentrations were low enough to suggest that there was enough respiratory oxygen consumption to measurably affect water quality, particularly so at the pig impacted wetland in Kalan wetlands (K2; Figure 3.1). The DO concentrations in a healthy productive lentic waterholes should fluctuate substantially reaching a minimum in the morning just before sunlight begins to penetrate the water column and rising to a significantly higher maximum in the mid to late afternoon – this pattern was observed in most wetlands here. It is very common to record daily minima that are well below the asphyxiation thresholds of sensitive fish species at pristine reference sites (see Waltham et al., 2013). Local species tolerate these brief episodes of hypoxia surprisingly well, provided that concentrations return to sufficiently high levels during the middle of the day, which is seen the data here (excluding K2 wetland). Data on the hypoxia tolerances of local species and detailed information on how to interpret DO data are available (Butler and Burrows 2007). Tolerances vary between species and life stages but the following summary provides an adequate basis for interpreting the variations observed at these study sites: None of the local freshwater fish species tested to date attempt to regulate their breathing until DO falls to concentrations below about 75% saturation. At concentrations lower than that most fish must regulate their breathing, generally by increasing ventilation rates (the piscatorial equivalent of panting); hence the lower the DO saturation the greater the amount of energy expended in order to breathe. Long term exposure to saturation concentrations below 50% can potentially result in energy deficits and consequent reduction in growth rate and fecundity; nevertheless, many local species successfully exploit waters with DO concentrations significantly lower than that. Regulatory failure and potential asphyxiation occurs at about 30% in the most sensitive local fish species and around 10% to 15% in sensitive invertebrates. Below those concentrations the number of species affected increases with declining DO concentrations. Fish in the wild survive regular exposure to concentrations below those thresholds by rising to the surface to utilise aquatic surface respiration and/or air gulping. Their capacity to do that safely depends on the timing of the oxygen sag and antecedent conditions. Notably it appears that most of the mortality associated with hypoxia-induced Page 16


fish kills is actually due to exposure (e.g., thermal stress and sunburn) resulting from the animals’ need to remain at the surface during the heat of the day. The above information is of value for interpreting the potential ecological significance of DO fluctuations but they are of limited use for setting limits in ephemeral habitats because concentrations below the tolerance limits occur so commonly in nature. Moreover, DO variations are driven by such complex interacting factors, most of which are localised in time and space, that it is not feasible to develop meaningful guidelines or comparisons. It is pertinent to note that naturally hypoxic aquatic habitats are not uncommon and probably play a vital role in maintaining regional biodiversity. For example, there are hypoxia-tolerant fish and invertebrate species (and perhaps amphibians) which appear to rely upon the existence of oxygen-depleted habitats or micro-habitats to avoid competition and predation from more active species with greater oxygen requirements. pH is also potentially subject to the same kinds of biogenic fluctuations as DO, due to consumption of carbon dioxide (i.e. carbonic acid) by aquatic plants and algae during the day (through photosynthesis), and net production of carbon dioxide at night. If respiratory oxygen consumption is predominant, DO concentrations are low and pH values are generally moderately acidic to neutral (which was the case for wetlands examined here). All photosynthetically active organisms utilise carbon dioxide as a preferred carbon source. Some species (including most green algae) are unable to photosynthesise if carbon dioxide is unavailable, but there are other species (including most cyanobacteria and submerged macrophytes) which can utilise bicarbonate as an alternative carbon source. Carbon dioxide consumption causes pH to rise to values in the order of 8.6 to 8.7 (but that was note the case here during this survey period).

Table 3.1

Summary statistics for hydrolab loggers in wetlands during this survey Min Temp Max Temp Mean Temp ( C)

( C)

( C)

Min EC (μS/cm)

Max EC (μS/cm)

Mean EC (μS/cm)

Min pH

Max pH

Mean pH

AR2_Outside

23.91

30.59

26.15

33.00

39.00

34.93

5.47

6.09

AR3_Inside

24.42

28.82

26.13

17.00

19.00

17.83

4.95

6.04

AR3_Outside

24.26

28.72

25.95

20.00

21.00

20.23

4.61

AR4_Outside

21.62

25.90

23.29

27.00

30.00

28.25

AR5_Inside

17.75

34.71

24.77

17.00

20.00

11.85

23.36

26.42

24.77

11.00

12.00

20.36

22.82

21.39

91.00

105.00

Site

o

o

o

Min DO (% Sat)

Max DO (% Sat)

Mean DO (% Sat)

5.71

1.40

102.60

29.06

5.47

19.70

93.70

52.25

4.84

4.71

9.50

64.00

31.91

5.67

6.14

5.82

9.10

87.60

34.71

4.18

5.65

4.79

18.20

106.20

67.44

11.99

4.62

5.27

5.01

14.30

49.40

28.35

95.30

5.76

5.93

5.88

0.40

12.40

1.64

AR2_Inside

AR4_Inside

AR5_Outside AR6_Inside AR6_Outside K1_Pig K2_Cattle

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Start: 24 Jun 2015 19:00 Mean Temp: 25.9 °C Dissolved Oxygen

c)

End: 26 Jun 2015 17:20 Temp Range: 24.3 - 28.7 °C pH 11

180 160

9

120

8

100

pH 7

80 60

180

10

160 9

140 120

8

100

pH 7

80

6

40

5

0

10

12:00

00:00

12:00

2500

35

2000

30

1500

25

1000

20

500

15

0

10

12:00

15

End: 01 Jul 2015 07:30 Temp Range: 20.4 - 22.8 °C Temperature 40

00:00

500

Start: 29 Jun 2015 19:20 Mean Temp: 21.4 °C Conductivity

12:00

20

00:00

1000

12:00

25

00:00

1500

12:00

30

Archer River - K2_Cattle Mean EC: 95 µS/cm Mean DO: 1.6 % Sat 3000

Temperature °C

2000

Temperature °C

35

00:00

d)

End: 26 Jun 2015 17:20 Temp Range: 24.3 - 28.7 °C Temperature 40

2500

12:00

4 12:00

00:00

12:00

00:00

Start: 24 Jun 2015 19:00 Mean Temp: 25.9 °C Conductivity

0

Electrical Conductivity µS/cm

Archer River - AR3_Outside Mean EC: 20 µS/cm Mean DO: 31.9 % Sat 3000

12:00

00:00

4 12:00

0

5

20 00:00

20

Electrical Conductivity µS/cm

End: 01 Jul 2015 07:30 Temp Range: 20.4 - 22.8 °C pH 11

60

6

40

b)

Start: 29 Jun 2015 19:20 Mean Temp: 21.4 °C Dissolved Oxygen

200

10

140

Archer River - K2_Cattle Mean EC: 95 µS/cm Mean DO: 1.6 % Sat

00:00

Dissolved Oxygen % Saturation

Archer River - AR3_Outside Mean EC: 20 µS/cm Mean DO: 31.9 % Sat 200

12:00

a)

Examples of the kinds of diel dissolved oxygen, pH, water temperature and conductivity measured in Archer River wetlands. In these examples, AR3_outside wetland (a and b) which during this survey had minimal pig impact, while K2 (c and d) was heavily impacted by pigs (but not cattle)

Dissolved Oxygen % Saturation

Figure 3.1

Page 18


3.1.2 Pug marks – water temperature loggers Water temperature loggers deployed in a series of pug marks formed by pigs digging along the margins of AR4 (outside) and also for loggers deployed in the actual wetland (depth of 0.2m) are presented in Figure 3.2. The most noteworthy finding here is the water temperature measured in the pug marks had a higher maximum temperature, lower temperature, and therefore by difference pug marks had a one hour temperature amplitude of up to 7.8oC. The primary reason for this difference is related to differences in thermal mass; smaller waterbodies can more change compared to larger waterbodies that have a larger mass where water temperature will more gradually change. Figure 3.2

Continuous water temperature in: a) wetland; and b) pug marks formed on the margins of the same wetland

a)

Wetland 30

Water 1 Water 2

Water temperature oC

Water 3

25

20

15 25/06/15

26/06/15

26/06/15

27/06/15

27/06/15

28/06/15

28/06/15

29/06/15

Date/Time

b)

Pug marks

40

Pug 1 Pug 2

Water temperature

35 Pug 3 (Rep 1) Pug 3 (Rep 2) 30

25

20

15 25/06/2015

26/06/2015

26/06/2015

27/06/2015

27/06/2015

28/06/2015

28/06/2015

29/06/2015

Date/time

Page 19


Table 3.2

3.2

Summary statistics for the continuous water temperature loggers in wetland and pug marks during the logging period. Data for sites pooled for the logging period. Highest 1hr amplitude is the maximum water temperature increase for the logging period

Location

Min Temp (oC)

Max Temp (oC)

Mean (oC)

SE

Highest 1hr amplitude (oC)

Wetland

22.24

26.87

23.92

0.03

1.54

Pug mark

20.04

36.78

25.01

0.102

7.82

Aquatic fauna

3.2.1 Aquatic macroinvertebrates The sampling campaign completed here provides a starting point to examine the community structure and spatial differences in the aquatic macroinvertebrate community. While only a single survey did not yield sufficient samples to be able to perform statistically rigorous analyses, such analyses will be possible in the future as the database grows. To assist interpretation, results from a more extensive monitoring program that TropWATER has across northern Queensland has been examined. The raw macroinvertebrate data collected during this survey are tabulated in the Appendix of this report. A total of 43 macroinvertebrate taxa were recorded in these wetlands. The most common taxa (percent occurrence) was Cladocera (water flea), Chironominae (non-biting mides), Baetidae (mayflies), Copepoda (crustacea), Dytiscidae (diving beetles), and Odonata HUL complex which were found at more than 80% of locations (see Appendix). Freshwater crabs, common in northern Queensland ephemeral coastal rivers (Waltham et al., 2014), were also recorded in the Kalan wetlands (Austrothelphusa sp. – to be identified using genetics). It is noteworthy in the context of the data here, that the wetlands examined have reported slightly higher SIGNAL scores compared to data collected from ephemeral waterholes in southern Gulf catchments (Table 3.3). These higher SIGNAL scores are indicative of faunal communities dominated by species with high tolerance of good water quality conditions (e.g., high dissolved oxygen, low EC and low nutrient concentrations; Chessman 2003). Monitoring conducted by TropWATER in connection with other projects in northern Queensland indicates that ephemeral sites (albeit somewhat far more ephemeral than the wetlands examined here) typically report SIGNAL values below 3, which would generally be interpreted as being indicative of impairment and potential impact by local land use activities. For the other diversity indices (Shannon Diversity, H’Max, Evenness J’) the scores here for Archer River wetlands were generally higher in comparison to other ephemeral rivers in southern Gulf catchments (again reflecting the condition of each wetland at this stage of the year, and before major water drying stress on fauna, and impact from feral pigs). The only other TropWATER macroinvertebrate wetland dataset where it is remotely possible for comparison with the data here (coastal wetlands near Townsville), has generally similar SIGNAL and diversity scores. Overall, the scores for the Archer wetland sites (including the two Kalan wetlands with animal exclusion measures adjacent to Peach Creek K1 and K2) rank among some of the higher values that TropWATER have recorded. However, strictly comparable comparison with similar wetlands to Archer River wetlands are not possible at this time, but could occur in the future as more data from these wetlands becomes available. In addition, these data reflect the results of only a single survey and therefore may not be typical during later stages of the dry season and under further impact of feral pig damage, for example.

Page 20


Table 3.3

Tax counts and index values for macroinvertebrate communities at all sites recorded during June 2015

Macrophytes

AR2 AR2 AR3 AR3 AR4 AR4 AR5 AR5 AR6 AR6 K1 K2

Out In Out In Out In Out In Out In

302 205 192 243 475 287 42 215 37 138 132 142

20 22 21 23 24 25 4 22 14 20 15 21

2.54 2.94 3.00 2.88 2.67 2.67 2.00 2.80 3.11 2.79 2.78 2.60

Shannon Diversity (H') 2.60 2.72 2.68 2.70 2.59 2.78 0.84 2.79 2.29 2.58 2.32 2.44

Bottom

AR2 AR2 AR3 AR3 AR4 AR4 AR5 AR5 AR6 AR6 K1 K2

Out In Out In Out In Out In Out In

291 111 72 141 232 89 46 119 45 33 244 321

20 20 12 18 26 12 7 17 11 9 22 25

3.15 3.08 3.22 3.38 2.65 3.22 2.75 3.27 2.67 2.57 2.75 2.63

2.32 2.57 1.92 2.22 2.73 1.86 1.38 2.26 1.82 1.54 2.58 2.70

Habitat

Wetland Position

Taxonomic Total Abundance Richness

SIGNAL

H'max

Evenness (J')

3.00 3.09 3.04 3.14 3.18 3.22 1.39 3.09 2.64 3.00 2.71 3.04

0.87 0.88 0.88 0.86 0.81 0.86 0.61 0.90 0.87 0.86 0.86 0.80

3.00 3.00 2.48 2.89 3.26 2.48 1.95 2.83 2.40 2.20 3.09 3.22

0.77 0.86 0.77 0.77 0.84 0.75 0.71 0.80 0.76 0.70 0.83 0.84

Multivariate analyses The two-dimensional ordination plot in Figure 3.3 shows that there was, although not significantly different at the 0.05 probability level, separation among wetlands in the ordination (Table 3.4). Interesting, there was no significant between edge habitat and bottom communities across all sites (Table 3.4), a pattern that is commonly found in locations elsewhere in northern Queensland. The main species contributing to the separation of wetlands in the ordination plot (Figure 3.4) were Nepidae (SIMPER 5.16% contribution) (Figure 3.5), and Belostomatidae (SIMPER 4.60% contribution). There were too few data points to include a comparison here between inside and outside wetlands, but this could be completed in the future with more data.

Page 21


Figure 3.3

Two dimensional ordination plot of macroinvertebrate assemblage in wetlands examined in this survey. Green circles are macrophyte habitat and blue circles are wetland bottom habitat. Open circles are outside and closed are inside wetland position. Only single positions occur for K1 (pig/cattle) and K2 (cattle) exclusion wetlands. Data has a presence/absence transformation K2 K1

K2

K1

Table 3.4

Tax counts and index values for macroinvertebrate communities at all sites recorded during June 2015

Source

df

SS

MS

Pseudo-F

P (Perm)

Perms

Habitat (Ha) Wetland (We) Ha x We Residual Total

1 6 6 10 23

8.0833 47.667 29.167 58.5 146.42

8.0833 7.9444 4.8611 5.85

1.3818 1.358 0.8309

0.1901 0.0816 0.8189

9925 9664 9854

Page 22


Figure 3.4

Two dimensional ordination plot of macroinvertebrate assemblage in wetlands examined in this survey. Size of green circles is proportional to number of Nepidae recorded, with larger circles highest numbers and no circle representing Nepidae absent

.

K2 K1

K2

K1

Figure 3.5

Water scorpion (Nepidae) found predominately in aquatic vegetation habitat

http://www.mdfrc.org.au/bugguide/display.asp?type=5&class=17&subclass=&Order=3&family=55&couplet=0

Page 23


3.2.2 Fish assemblage Baited Remote Underwater Videos (BRUVs) In total, 15 fish species, were detected at 6 wetlands during the course of the survey (Table 3.5). Wetlands AR5 (combined inside and outside) had the highest diversity with 9 species, followed by site AR3 and AR5 with 8 species, and 6 species detected at AR2 and AR4. The only Kalan wetland where BRUVs could be used successfully was K1 (pig and cattle fenced wetland; K2 was had high turbidity which would limit ability to view fish) showed the lowest diversity with 4 species detected. The eastern rainbow fish (Melanotaenia s. inornata) and spangled perch (Leipotherapon unicolor) were detected in all wetlands, whereas empire gudgeon (Hypseleotris sp.), mouth almighty (Glossamia aprion) and bony bream (Nematolosa erebi) were recorded in one wetland (Table 3.6). The MaxN ranged between 1 individual (Glossamia aprion) to over forty (Craterocephalus stercusmuscarum) for a single BRUV station (Table 3.6). The arrival times for fish were also variable, with mean times ranging from 121 sec to 1833 secs, with the larger bodied species generally having the most slow arrival times (see freshwater longtom, seven-spot archerfish). Both the fly specked hardyhead (Craterocephalus stercusmuscarum) and eastern rainbow fish (Melanotaenia s. inornata) had an average arrival time in the video within three minutes of deploying the BRUV, with the freshwater longtom (Strongylura krefftii) having an average arrival time of approximately 30 mins. Interestingly, the recording of empire gudgeon (probably Hypseleotris compressa; Figure 3.6) which according to Allen et al., 2002 is likely to occur in the region) in AR2 is the first recording for this species in the catchment, with no single recording in the Northern Australia Freshwater Fish (NAFF) database.

Table 3. 5

Fish community composition inside and outside proposed fencing sections in each wetland surveyed using BRUVs. Numbers are pooled for replicates. * denotes diadromous movement ecology Site AR2 AR2 AR3 AR3 AR4 AR4 AR5 AR5 AR6 AR6 K1 Position Outside Inside Outside Inside Outside Inside Outside Inside Outside Inside Inside

Scientific name Ambassis sp. Amniataba percoides Craterocephalus stercusmuscarum Glossamia aprion Hypseleotris sp* Iriatherina werneri Leiopotherapon unicolor Nematolosa erebi Melanotaenia nigrans Melanotaenia s. inornata Melanotaenia trifasciata Mogurnda mogurnda Scleropages jardini Strongylura krefftii Toxotes chartareus Replicate Species richness Total

Common name Glass perch Banded grunter Fly specked hardyhead Mouth almighty Empire gudgeon Threadfin rainbowfish Spangled perch Bony bream Black banned rainbow Eastern rainbow Banded rainbow Purple spot Gulf saratoga Freshwater longtom Seven-spot Archerfish

4

1

6

4

3

1

5 3 18 1

16

14

1

9

45

4

24 1

4 2

4

2

2

43 7

16 4

62 4

52

53

12 43

4 22

8

6

22 6 6

2 2 1 2 7 64

1 1 2 3 9 86

3 7 130

2 6 67

3 4 35

1

4 4 2

4

1

14 15

16

3 12

15

28

1 1 2 4 25

3 5 26

2 6 47

1 3 7 36

2 2 42

3 5 118

Page 24


Table 3.6

Summary of detection rates and maximum number of individuals observed (MaxN) for aquatic fauna by baited remote underwater video stations (BRUVS). * denotes diadromous movement ecology. Arrival time data that is underlined denotes detection at a single BRUVS precluding calculation of standard error Species name

Common name

Ambassis sp. Amniataba percoides Craterocephalus stercusmuscarum Glossamia aprion Hypseleotris sp* Iriatherina werneri Leiopotherapon unicolor Nematolosa erebi Melanotaenia nigrans Melanotaenia s. inornata Melanotaenia trifasciata Mogurnda mogurnda Scleropages jardini Strongylura krefftii Toxotes chartareus Chelodina oblonga

Glass perch Banded grunter Fly specked hardyhead Mouth almighty Hypseleotris sp. Threadfin rainbowfish Spangled perch Bony bream Black banned rainbow Eastern rainbow Banded rainbow Northern trout gudgeon Gulf saratoga Freshwater longtom Seven-spot Archerfish Northern Long-necked Turtle

Figure 3.7

Detection rate (%) 83 17 67 17 17 33 100 33 33 100 50 33 33 33 33

MaxN 8 3 41 1 4 21 4 4 8 36 5 14 2 2 2 1

Arrival time sec (+se) 570 (169) 2631 121 (27) 1400 807 279 (162) 509 (134) 281 (95) 255 (179) 134 (33) 161 (75) 281 (95) 603 (284) 1833 (703) 1298 (654)

Frame pictures from BRUVs in Archer River wetlands. A) freshwater longtom (Strongylura krefftii); B) mouth almighty (Glossamia aprion); C) eastern rainbow (Melanotaenia s. inornata); and D) empire gudgeon (Hypseleotris sp.)

A)

B)

C)

D)

Page 25


Multivariate analysis There was no significant difference in fish assemblages between inside and outside proposed fencing areas (analysis excluded K1; Figure 3.8), nor was there a significant interaction between wetland and position (inside or outside) (Table 3.7). There was however clear structure in fish assemblage (based on presence/absence using the Bray Curtis transformation) with wetlands separated across the ordination plot. These differences among wetlands (Table 3.6) were driven by several fish species that were detected in some wetlands and not others. Figure 3.9 shows the presence of Threadfin rainbow (Iriatherina werneri) present in AR2, AR3 and AR6, but not other wetlands. Figure 3.8

Two dimensional ordination plot of fish community using BRUVs in wetlands examine in this survey. Filled circles are deployments within fencing sites (planned or in the case of Kalan pig exclusion wetlands: K1), while open circles are outside proposed fencing sites 2D Stress: 0.12 AR5

AR5

AR5

AR5

AR4 AR4 AR4 AR3

AR2 AR3 AR4 AR5

AR2

AR3, AR5

AR4

AR2

AR3

AR2

AR3 AR2 AR3 AR6

K1 AR6 AR6 K1 K1

Table 3.7

PERMANOVA results for wetlands and position (inside and outside) Source

df

SS

MS

Pseudo-F

P (Perm)

Perms

Wetland (We) Position (Pos) We x Pos Residual Total

4 1 4 15 24

7438.9 233.38 2174.1 8772.7 18522

1859.7 233.38 543.53 584.85

3.1798 0.39905 0.92936

0.0058 0.7054 0.5089

9949 9969 9949

Page 26


Figure 3.9

Two dimensional ordination plot of fish community using BRUVs in wetlands examine in this survey. Green circles show wetlands were Threadfin rainbow (Iriatherina werneri) fish was present. Site codes without green circle threadfin rainbow absent 2D Stress: 0.12 AR5

AR5

AR5

AR5

AR4 AR4 AR4 AR3

AR2 AR3 AR4 AR5

AR2 AR4

AR2

AR3

AR2

AR3 AR2 AR3 AR6

K1 AR6 AR6 K1 K1

3.2.3

Baited fish traps

A total of five species were recorded using baited fish traps (Table 3.8). The most common species caught using this method was the freshwater crayfish (Cherex sp. – identification to be confirmed), caught in all wetland sites, both inside and outside proposed fencing locations. The exception were the two Kalan wetlands, which might simply reflect a more coastal range, and that it might not occupy waters at a high altitude in the catchment. While crayfish were absent from the catchment in both Kalan wetlands, the northern trout gudgeon and eastern rainbow fish were recorded using this survey method. Table 3.8

Total catch in baited fish traps deployed in wetlands Site

AR2

Scienctific name

Common name

Mogurnda mogurnda

Northern trout gudgeon

Cherex sp.

Freshwater crayfish

9

Amb assis sp.

Glass perch

5

Glossamia aprion

Mouth almighty

1

Melanotaenis splendida inornata

Eastern rainbow fish

Species richness Total

AR2

Position Outside Inside 43

AR3

AR3

AR4

AR4

Outside Inside Outside Inside 13

23

9

7

AR5

AR5

AR6

AR6

K1

K2

Outside Inside Outside Inside 12

16

4

12

15

11

2

12

9 11

3

1

1

1

1

2

1

1

2

2

2

1

15

43

13

23

9

16

4

12

27

27

13

12

Page 27


3.2.4 Freshwater turtles Total trapping effort consisted of 24 sites for an average of 16.5 hours per trap site, for a total sampling effort ~396 trap hours. Over the course of the survey a total of 18 turtles were captured comprising three species (Table 3.9). Of these, 11 individuals were identified as Northern long-neck (Chelodina oblonga) and five were Worrell’s short-neck (Emydura s. worrelli) (Figure 3.10). In addition to these data, a single Cann’s long-necked turtle (Chelodina canni) individual was caught (28 June 2015) just prior to this survey on the road near Stoney Crossing (approx. -13.658711°, 141.726626°) by Brian Ross (this specimen was not photographed pers comm and a single juvenile C. oblonga was detected on BRUV footage at AR6 (inside) (Figure 3.11).

Table 3.9

Freshwater turtle trapping survey site/capture summary Date

Site code

Location

Replicate

C. oblonga

26/06/2015

AR2

inside

1

26/06/2015

AR2

inside

2

26/06/2015

AR2

outside

1

26/06/2015

AR2

outside

2

1

25/06/2015

AR3

inside

1

1

25/06/2015

AR3

inside

2

1

25/06/2015

AR3

outside

1

25/06/2015

AR3

outside

2

27/06/2015

AR4

inside

1

27/06/2015

AR4

inside

2

27/06/2015

AR4

outside

1

27/06/2015

AR4

outside

2

28/06/2015

AR5

inside

1

28/06/2015

AR5

inside

2

28/06/2015

AR5

outside

1

28/06/2015

AR5

outside

2

28/06/2015

Archer River

1

28/06/2015

Archer River

2

29/06/2015

AR6

inside

1

29/06/2015

AR6

inside

2

29/06/2015

AR6

outside

1

29/06/2015

AR6

outside

2

1/07/2015

K1

inside

1

3

1/07/2015

K1

inside

2

3

E. s. worrelli

1 2

1

1

1

1

Archer River wetland sites A total of 9 adult turtles comprising two species (Chelodina oblonga, Emydura. s. worrelli) were trapped in the wetland (Table 3.9). The Northern long-neck (C. oblonga, formerly C. rugosa) were more widespread, caught at four wetlands, compared to Worrell’s short-neck (E. s. worrelli) which was found at only two sites. Summary statistics on the straight carapace length and weight of both species are shown in Tables 3.10 and Table 3.11. Of these sites, AR3 had the highest abundance and diversity with a total of two Northern long-neck (one male, one female) and three Worrell’s short neck Page 28


(three females). A single individual Northern long-neck was captured in each of the other wetlands (AR2, AR4, AR5, and AR6). Two additional traps were set in the Archer River main channel, but failed to catch turtles with one trap damaged by an estuarine crocodile. Figure 3.10

Example of northern long neck (C. oblonga) and Worrell’s short neck (E. s. worrelli). Both turtles captured in AR3

Figure 3.11

Juvenile Northern long neck turtle (C. oblonga) observed on BRUV footage from AR6 (inside).

Page 29


Tables 3.10

Tables 3.11

Summary statistics for straight carapace length (SCL) and weight for C. oblonga individuals measured at the Archer River wetlands

SCL Male (n=3) Female (n=3)

Min (mm) 250.8 276

Mean (mm) 257.6 313.9

Max (mm) 268.8 354.9

Weight Male (n=3) Female (n=3)

Min (g) 2250 3100

Mean (g) 2533.3 4600

Max (g) 2650 6700

SD 19.71 36.87 SD 550.15 1484.33

Summary statistics for straight carapace length (SCL) and weight for female E. s. worrelli individuals measured at the Archer River wetlands. (The capture of a single male precludes any morphometric summary statistics, see Appendix 1)

SCL (mm) Female (n=3)

Min 225.5

Mean 259.63

Max 276.9

SD 29.56

Weight (g) Female (n=3)

Min 1450

Mean 2333.33

Max 2850

SD 768.66

Kalan wetlands A total of seven turtles comprising two species (C. oblonga and E. s. worrelli) were captured in the two traps set in the Kalan wetlands inside a pig exclusion fence (Table 3.12). Of these, six were C. oblonga (three male, three juveniles) and one female E. s. worrelli (SCL=187mm). These turtles were generally smaller in comparison to individuals caught in the wetlands adjacent to the Archer River. No turtles were captured during the limited trapping (1 hr/trap) in the wetland (K2) which was fenced to exclude cattle only. Tables 3.12

Summary statistics for straight carapace length (SCL) and weight for C. oblonga individuals measured at the Kalan wetland pig exclusion site (K1)

SCL (mm) Male (n=3) Juvenile (n=3)

Min 193 139

Mean 210 150.33

Max 221 161

SD 37.38 34.04

Page 30


4

DISCUSSION AND CONCLUSIONS

4.1

Wetland water quality

Water quality data collected from the wetlands here provides a valuable starting point for longer term condition assessment and comparison as the proposed feral pig fencing strategy commence and become established. Not surprisingly, there were little differences between ‘inside’ and ‘outside’ proposed fencing areas within a single wetland at this early stage of mitigation. However, notwithstanding this there were differences in the cycling patterns among wetlands, namely the Kalan wetland (K2) that had cattle only fencing. These among wetland differences probably reflect local environmental conditions and morphological features that typically influence water quality conditions (Waltham et al., 2013; Wallace et al., 2015). At this point there are insufficient baseline data (spatial and temporal scale) to complete meaningful interpretation of water quality in these wetlands. (The logging data is however more appropriate than spot measurements that are typically collected in wetlands across northern Australia). The limitations in the data is due partly to the short logging period, but also given antecedent rainfall in the catchment in the 2014/15 wet season was below average, so it would be expected that conditions would change under more average or higher rainfall years. An interesting pattern in the logging data occurred in cattle fenced wetland (K2). The impact from feral pigs has obviously contributed to the loss of fringing aquatic macrophytes (Figure 4.1), and in doing so these actions elevate turbidity in the water column, which was confirmed with the secchi depth recording of 0.05m, compared to >0.5m in other wetlands examined). Water clarity (turbidity) has been shown recently to affect the thermal regime of waters in northern Queensland, whereby surface waters are substantially warmer than bottom waters, owing to the turbidity of water retaining heat in the surface waters, and not allow heat to extend to deeper waters (Wallace et al., in press). The impact of pigs and their feeding activities may have contributed to the very low dissolved oxygen concentrations measured in K2, contributing to the resuspension of bottom nutrient rich sediments and oxygen consuming organic material (Pearson et al., 2003). Dissolved oxygen concentrations this low in K2 are critical for the survival of aquatic fish (Butler and Burrows 2007), so it’s not surprising that this wetland had the lowest diversity of fish. The pug hole water temperature survey provided the first test of the model that breaking up a wetland margin into a smaller, shallow, waterholes, effectively allows water temperatures to increase to much higher levels (compared to the main wetland waterbody) because of a smaller mass. The concern here with many smaller waterholes that heat quickly during the day is that evaporation also increases, therefore conceivably causing wetlands to dry more rapidly compared to wetland that have an intact margin, un-impacted by feral pigs. While the evidence provided is not conclusive, and is based on only a single wetland site, additional replication using multiple wetland sites under different seasonal conditions, in combination with laboratory manipulative experiments, would confirm this model.

Page 31


Figure 4.1

Time lapse photos of wetland near Coen with cattle exclusion fence, while pigs are still able to access. A) photo 22 June 2015; and B) 16 September 2015 (note small horse has accessed this wetland) (Photos provided by Brian Ross, Balkanu Cape York Development Corporation)

A)

B)

4.2

Aquatic fauna

Macroinvertebrate community The wetlands examined supported diverse range of macroinvertebrate species. Differences in the composition among wetlands is not surprising, and probably reflects local microhabitat conditions, different levels of predation impacts, and differences in habitat complexity. These data highlight that sufficient wetland replication is necessary in order to avoid false conclusions in the interpretation of the data. In addition, seasonal affects have not be examined here, and future programs would need to include a more temporal assessment in order to appropriately characterise fauna assemblage. While a cursory examination of the data was completed by comparing to available aquatic macroinvertebrate data from other programs, the results should not be viewed in any detail. It is commonly accepted that even the subtle differences in habitat conditions (e.g., flow, sediment, vegetation, water quality, shading, predation etc.) can contribute to hierarchical differences in assemblages among study sites. While wetlands supported different species composition, a more interesting point was overlapping composition of species between ‘inside’ and ‘outside’ fencing in a wetland site. This is an important starting point in the feral pig fencing strategy where it would be expected that the fenced section of the wetland should support an entirely different macroinvertebrate Page 32


assemblage compared to the unfenced (pig impacted area). On-going assessment of aquatic macroinvertebrate community in these wetlands, particularly following feral pig fence installation, will be important in testing this hypothesis.

Freshwater fish The TropWATER Northern Australia Freshwater Fish (NAFF) database has a total of 48 species of freshwater fish recorded in the Archer River catchment (Table 4.1). This database is a consolidation of all available data records sourced from museums, scientific research projects and government consultancies, covering all the tributaries across the catchment. Importantly, there have been no recording of invasive fish, such as the tilapia (Oreochromis mossambicus) which is widespread on the east coast of Queensland, essentially south of Cairns. On this basis, the fish species list generated during this study represents a subset of the community in the catchment. Many of the species in the main river channel probably occur in these wetlands, however, they were not recorded in this short field trip. While the lower species richness recorded in the wetlands might be attributed to continuing impacts on the wetlands caused by feral pigs, it is probably more likely owing to the limited sampling opportunities in these wetlands. In this study, only baited traps and BRUVs were used to examine fish species community. While these methods are being used increasingly so in freshwater surveys, as a non-destructive method, the method can under-represent total community, given larger species might not be always attracted to the bait used. In addition, the lower species richness is also a consequence of the different frequency and duration of connection between wetlands and the main Archer river channel. The wet season rainfall immediately prior to this survey was below average, in fact was within the 10th percentile for historical records. In order to compare the species composition and seasonality of the freshwater fish assemblage inhabiting Archer River and the wetlands examined here, we used the taxonomic distinctness (AvTD, Δ+) and its variation (VarTD Δ+) obtained with the TAXDTEST routine of the PRIMER 6.0 software (Clarke and Warwick 2001). This allowed us to calculate the average taxonomic relatedness for samples, as well as compare this to the range of values calculated by repeatedly taking random samples of the same size (as number of species) from an appropriate master list. In our case, the master list was based on the NAFF database using fish data records (including 263 fish species and 501 field records) obtained from Cape York, western Cape and southern Gulf drainage basins (Nicholson River, Leichhardt River, Flinders River, Norman River, Gilbert River, Mitchell River, Archer River (including Archer River wetlands in this study), Holroyd River, Colman River, Wenlock River, Jardine River). TAXDTEST results (Figure 4.2) suggest that the Archer River wetlands support a fish composition that is generally within the taxonomic distinctness of other river catchments on the western cape, though is probably below expected number of species (though the results are probably confounded with respect to temporal and spatial replication, and the sampling methods used). Additional data and using additional sampling strategies would increase the taxonomic distinctness of these wetlands.

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Table 4.1

List of freshwater fish species in the Archer River catchment recorded in the NAFF, along with those recorded during this wetland survey

Family

Genus

Species

Common name

Apogonidae Ariidae

Glossamia Neoarius Neoarius Neoarius Neoarius Craterocephalus Strongylura Lates Ambassis Ambassis Ambassis Ambassis Ambassis Denariusa Nematalosa Dasyatis Mogurnda Oxyeleotris Oxyeleotris Oxyeleotris Oxyeleotris Thryssa Glossogobius Glossogobius Glossogobius Glossogobius Megalops Iriatherina Melanotaenia Melanotaenia Melanotaenia Melanotaenia Scleropages Anodontiglanis Neosilurus Neosilurus Neosilurus Porochilus Pristis Synaptura Ophisternon Amniataba Hephaestus Hephaestus Leiopotherapon Scortum Toxotes Toxotes

aprion berneyi graeffei leptaspis paucus stercusmuscarum krefftii calcarifer spUNKNOWN spNORTHWEST agrammus elongatus macleayi bandata erebi spUNKNOWN mogurnda spUNKNOWN nullipora lineolatus selheimi scratchleyi aureus giuris sp2MUNROI sp3DWARF cyprinoides werneri nigrans splendid inornata trifasciata spUNKNOWN jardinii dahli spUNKNOWN ater hyrtlii rendahli pristis salinarum spUNDESCRIBED percoides carbo fuliginosus unicolor ogilbyi chatareus jaculatrix

Mouth almighty Berney’s catfish Lesser salmon catfish Triangular shield catfish Silver cobbler Fly-speck hardyhead Long tom Barramundi Glass perch Northwest glassfish Sailfin glassfish Elongate glassfish Macleay’s glassfish Pennyfish Bony bream Stingray Northern trout gudgeon Gudgeon Poreless cod Sleepy cod Giant cod

Atherinidae Belonidae Centropomidae Chandidae

Clupediae Dasyatidae Eleotridae

Engraulidae Gobiidae

Megalopidae Melanotaeniidae

Osteoglossidae Plotosidae

Pristidae Soleidae Synbranchidae Terapontidae Terapontidae Terapontidae Terapontidae Terapontidae Toxotidae Toxotidae Total species

Golden goby Flathead goby Goby Goby Oxeye herring Threadfin rainbowfish Black-banded rainbowfish Eastern rainbow fish Banded rainbow fish Rainbowfish Saratoga Toothless catfish Eel-tailed catfish Black catfish Hyrtl’s tandan Rendahl’s catfish Freshwater sawfish Freshwater sole Swamp eel Banded grunter Coal grunter Sooty grunter Spangled perch Gulf grunter Archer fish Banded archerfish

Present in Archer River √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ 48

Present in wetlands √

√ √ √

√

√

√ √ √ √ √ √

√ √ √ 15

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Figure 4.2

Species accumulation (TAXDTEST, PRIMER routine) funnel plot using NAFF database for all river basins on Cape York, western Cape and southern Gulf. Green circles are Archer River channel sites (sourced from the NAFF), blue circles are wetland sites in this study. The 95% probability funnel (thick line from 1000 independent simulations for each subset size drawn randomly from the NAFF. Centre thin line denotes the theoretical mean for such random selections

100

80

Delta+

60

40

20

0 0

5

10

15

20 25 30 Number of species

35

40

45

50

High conservation value fish species In general, most freshwater fish species in northern Australia have wide distributions and broad habitat tolerances (Pusey et al., 2004). There are, however, several fish species with recognised conservation values. These are the freshwater sawfish (Pristis pristis) and the giant freshwater whipray (Himantura dalyensis) - note that H. dalyensis has recently been split from H. chaophraya which is recognised as endangered on the IUCN Red List. The freshwater sawfish is listed as Vulnerable under the Commonwealth EPBC Act, Endangered on the 2000 IUCN Red List of Threatened Species and Critically Endangered in south east Asia. It has been nominated for listing as ‘Vulnerable’ under the Queensland Nature Conservation Act (1992). Due to their saw-shaped rostrum, sawfish are easily identified by non-experts, although there are a number of sawfish species and the taxonomy of individual species is more challenging. The freshwater sawfish is known from at least 15 rivers across northern Australia, as well as south east Asia and India (Peverell, 2005; Thorburn et al., 2003). The freshwater sawfish is the most freshwater adapted of the sawfish species and may even be able to breed in freshwater (Pogonoski et al., 2002). Although often caught in estuaries, only a few specimens are reported from offshore areas. Freshwater sawfish can grow up to 7m in length, though Australian specimens are usually only up to 2 m long. Freshwater sawfish may occur up to 500 km upstream from the river mouth (e.g. Lynd River, Mitchell catchment, Queensland; Allen et al., 2002). Given their length and the saw-shaped rostrum, it is unlikely that sawfish would be able to negotiate instream passage barriers. However, given that they occur in both freshwaters and estuaries and are found long distances upstream, movements between those environments may be important and any passage barriers could reduce available habitat to complete Page 35


lifecycle stages. Being large predators, they may also be subject to declining habitat condition and affected by droughts or reduced wetland/waterhole size in river catchments. The Freshwater sawfish (Pristis pristis) has been recorded in the Archer River catchment (Figure 4.3), highlighting the importance of this river system (in addition to the off channel wetland complex) in the conservation of this charismatic species. The known distribution of this species in the catchment is undoubtedly much broader than is represented here in the Archer River catchment. This species (along with the giant freshwater whipray) are rarely caught using standard fish survey techniques and specialist techniques are required. Any proposal for development in the catchment will need to adequately investigate potential implications on this freshwater fish species. Figure 4.3

Recorded location of freshwater sawfish (Pristis pristis) in Archer River catchment (sourced from NAFF database). Red circles are wetlands examined in this study, yellow circles are recording sites of freshwater sawfish

The giant freshwater whipray is also poorly known, only being recognised as present in Australian freshwaters in 1989 (Taniuchi et al., 1991). Prior to that, all long-tailed stingrays from tropical Australian freshwaters were incorrectly referred to as an estuarine stingray species (Thorburn et al., 2003). The giant freshwater whipray can grow up to 2 m disc width and weigh up to 600 kg, although the largest recorded Australian specimen was 1 m disc width and 120 kg (Last, 2002). In Australia, it is known from the Daly, Alligator and Roper rivers (Northern Territory), the Pentecost and Ord, Fitzroy and Pentecost rivers (Western Australia) and the Flinders, Gilbert, Mitchell, Wenlock and Normanby rivers in Queensland (Peverell et al., 2005; Thorburn et al., 2003), but as it also occurs in Papua New Guinea and south east Asia, so it may, with further survey, be found in more northern Australian rivers (including the Archer River) (Pogonoski et al., 2002). Like the freshwater sawfish, this species is vulnerable to fishing as prey and bycatch, drought and fish passage barriers (either caused as a result of built infrastructure or flow alterations associated with land use changes).

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Freshwater turtles Three of the five species of freshwater turtles known from the Archer River catchment were identified in this study. The Archer River basin is home to five of the six species of freshwater turtles recorded from Cape York (Chelodina oblonga, Chelodina canni, Emydura subglobosa worrelli, Emydura tanybaraga and Myuchelys latisternum) with exclusion of E. subglobosa subglobosa which is endemic to the Jardine River Catchment (Freeman et al. 2014; Georges and Thomson 2010; Schaffer et al. 2009; Cann 1998). The Yellow faced turtle (Emydura tanybaraga) and Sawshelled turtle (Myuchelys latisternum) were not recorded at any sites during this survey. Myuchelys latisternum is uncommon in lentic environments, instead preferring perennial headwaters of streams and rivers (Cann 1998). However, M. latisternum has been recorded from Peach Creek (directly adjacent to the Kalan wetlands) and throughout much of Eastern Cape York Peninsula (Cann 1998; Georges and Thomson 2010). Two of the six species known to occur on Cape York Peninsula (Emydura s. worrelli and Emydura s. subglobosa) are listed as “Near Threatened” under the Queensland Nature Conservation Act (NCA) 1992, with the remaining species (Chelodina oblonga, Chelodina canni, Emydura tanybaraga and Myuchelys latisternum) listed as “Least Concern” (Figure 4.4). Examination of museum and tissue collection records (ALA; UCWTCD) show that the majority of collections and sightings of freshwater turtles in the Archer River catchment to date were undertaken in the middle to upper catchment area within Oyala Thumotang (formerly Mungkan Kandju) National Park and in the vicinity of Coen with additional limited sampling undertaken in the vicinity of Aurukun township (Watson River). This study therefore represents the first targeted survey of the lower downstream section of the Archer River (Proper) and its associated wetlands (Figure. 4.5).

Figure 4.4

Myuchelys latisternum female from Lankelly Creek northwest of Coen, Southwestern McLlwraith Ranges (Photo Stewart MacDonald 2015)

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Figure 4.5

Current distribution of freshwater turtle species within the Archer River and Watson River catchments compiled from the UCWTCD including records from the current surveys undertaken in June 2015

Distinguishing Emydura s. worrelli and Emydura tanybaraga The current bulk of records regarding the distribution of E. s. worrelli in Queensland is largely restricted to major rivers draining into the Gulf of Carpentaria such as the Gregory-Nicholson, Leichhardt (Georges and Thomson 2010) and Flinders drainages (Waltham and Butler 2014) (Figure 4.6). On Cape York specifically, examination of historical records for E. s. worrelli are sparse with only two records being recorded from the Archer River ~ 48 km north of Coen (n=57) and in the Wenlock River Drainage (n=1) (ALA; UCWTCD) (Figure 4.6). Individuals identified in this survey represent the first records of this species being recorded from the Western side of Cape York. In contrast to E. s. worrelli, records for E. tanybaraga show a distinct disjunction between populations in the NT and on Cape York Peninsula Qld (Figure 4.5). These two species are closely related, though there is some genetic divergence (Georges and Adams 1996), and are thought to occur in sympatry throughout much of their distribution across northern Australia (with the exception of rivers draining into the Gulf of Carpentaria). The apparent gaps in the distribution of these two species is possibly the result of identification difficulties in the field, with identification usually requiring careful examination of morphological and genetic sequence data (Georges and Thomson 2010; Georges and Adams 1996). Species differentiation via superficial characters such as leading/trailing eyespots/stripes, or the black edging on head stripes is inconsistent and proper diagnosis requires examination and measurement of skull features on the roof of the mouth (Thomson 2003) (e.g., Figures 4.7 and 4.8). Although no E. tanybaraga were recorded during this survey we have to assume they are present based on records from previous surveys within the Archer catchment (if they are correct) until further sampling can be undertaken (probably not. Arthur Georges pers comm).

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Figure 4.6

Current distribution of E. s. worrelli and E. tanybaraga across norther Australia (including data from the current study) showing an apparent disjunction E. tanybaraga populations in the NT and QLD

Figure 4.7

An individual Emydura subglobosa worrelli captured 25/06/2015 at Archer River Wetland site AR3 showing inconsistency in eye markings and facial striping. These two features are commonly used as identifiable characters for species diagnosis when differentiating it from E. tanybaraga

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Figure 4.8

Emydura s. worrelli captured from the Kalan wetlands (Turtle 1) and the Archer River wetlands (Turtle 2). Identification of and key features used to differentiate E. s. worrelli from E. tanybaraga: A) Triturating surface, B) Triangular gap in triturating surface over the internal nares; C) Unfused triturating surfaces; and D) Symphysis length of the lower jaw. (Photos Eric Vanderduys; CSIRO, 2015)

Presence and Movement Our experience with both survey techniques (trapping and BRUVs) has shown that they are effective in the capture and detection of turtles from all sizes classes over a wide range of environments. However, preliminary trapping/survey efforts undertaken during this survey precludes any solid inferences as to the overall drivers behind the presence and/or absence and population demographics of particular species at any particular site. In light of the limitations of the present study, it was interested that only 4 juvenile turtles (all C. oblonga) were captured/observed from a total of 24 sites. The high mortality of eggs and the paucity of juvenile recruitment is an increasingly common characteristic of Queensland turtle populations. Due to their highly cryptic nature, data on the ecology and survivorship of hatchling and juvenile turtles in Australia (particularly Queensland) is almost entirely lacking. However, a general lack of recruitment in many turtle populations has been attributed to high rates of egg predation by a variety of native and introduced predators (including foxes, pigs, dogs, goannas) and trampling by live stock (Hamann et. al 2007; Limpus et. al 2011). In the absence of other limiting factors such as adult mortality, nest predation and habitat degradation due to external factors such as feral pigs/livestock, it can be assumed that ephemeral wetland specialist species such as C. oblonga and C. canni would be more widely distributed throughout the floodplain wetlands due to their shared affinity for overland dispersal and terrestrial aestivation over the other sympatric turtle species such as Emydura sp. Although C. oblonga and C. canni are more or less ecologically equivalent, they differ in both their preferences for aestivation and ability to disperse overland. Chelodina canni are often encountered on land and frequently travel long distrances overland to reach new wetlands, as a posed to aestivating as wetlands dry (Cann 1998; Doupe´ et al. 2009). While the life history of C. canni is poorly known it is possible that C. canni also behaves in a similar fashion to sympatric PNG species, C. novaeguinea, which spends extensive periods on land Page 40


and is also known to aestivate in the dry season beneath leaf litter (Georges et al. 2006). Chelodina oblonga tends to either aestivate by digging in the mud, tucking itself into root masses along the banks as the wetland dries (Cann 1998; Fordham et al. 2006; Georges et al. 2006), or if necessary migrating overland, but only short distances to proximal water bodies (Doupe et al. 2009). In contrast to their long-necked counterparts, short-necked Australian chelid turtles including Emydura species are thought to be poorly adapted to prolonged desiccation and/or sustained aestivation (Cann 1998) precluding largescale overland movement by this group. However, Emydura sp. have at least some capacity to move between waterbodies as E. s. worrelli has been spotted previously (Eric Vanderduys, CSIRO, pers comm) wandering along the road between wetlands adjacent to the Archer River study area in the late dry season. Their overland range and exactly the length of time they can remain on land without needing to access water is not known. Additionally, Alastair Freeman (Queensland State Government, 2014) has previously noted that estuarine crocodiles may also be an important factor in whether individual Emydura sp. survive the dry season in off river refugia; a popular food item for estuarine crocodiles. Overall based on these findings, the proximity to large perennial/semi perennial waterbodies and the presence of predator species may play an important role in the persistence and determination of turtle species composition in floodplain wetlands in northern Queensland. Freshwater turtle conservation issues The vast majority of information concerning the effects of seasonality and feral animals on freshwater turtle populations has focussed on C. oblonga given that it is ubiquitous across northern Australia and it holds cultural value to local indigenous people. Chelodina oblonga is highly adapted to extreme seasonality and possesses demographic characteristics (rapid growth, maturity and high fecundity) and life history traits (underwater nesting followed by delayed embryonic development-diapause) that support populations in environments where adult survivorship is low (Kennett, 1996, 1999; Fordham et. al 2006). These traits allow C. oblonga to attain high densities in ephemeral swamps and other ephemeral wetlands in northern Australia (Fordham et. al 2006). Feral pigs (and livestock) are a significant concern as they are considered an imminent threat to freshwater turtles and their habitats in northern Australia either through predation, disruption of nesting activities, impeding movement between adjacent habitats (Fordham et al. 2006, 2008), increased rates of waterbody eutrophication (Doupe´ et al. 2009) and wetland desiccation (this study). Exclusion fencing for feral pigs and livestock as a management tool has been shown to protect ephemeral freshwater wetland habitats. However, freshwater turtle mortality associated with exclusion fences has been shown to effectively isolate populations to within the fenced area (Doupe´ et al. 2009; Primack 1998; Janzen 1983). Ferronato et. al. (2014) documented direct and indirect mortality (overheating and predation) to snake-necked turtles (C. longicollis) that became trapped behind exclusion fencing when trying to disperse between wetlands in south-eastern Australia. Based on that study, there is a risk that without access mitigation measures included into exclusion fencing, the enclosures themselves may negatively affect local freshwater turtle populations.

4.3

Aquatic wetland plants

Assessing aquatic plant community in wetlands is challenging when considering the large area to survey to compile a full species list, many plant species are underwater making access difficult, and can also be present at different times of the year. A case in point is the previous wetland aquatic plant assessment completed in Lakefield National Park where considerable variability existed between trips (across years) (Doupe et al., 2009). In addition to an inventory of aquatic plant species, riparian

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vegetation assessment is another important condition assessment tool used in wetland surveys, which does require more field time than was available here. Notwithstanding these challenges, preparing a comprehensive list of aquatic plant species can be achieved by seed bank assessment. In an attempt to start to examine more explicitly the composition and abundance of water plants in these wetlands, TropWATER obtained (with the assistance of CSIRO Land and Water personal, Townsville) soil samples collected (November 2015) from several wetlands examined here (Figure 4.8). By collecting the soil samples from the wetlands, we can examine the composition and abundance of the germinable seed bank and identify spatial patterns (including patterns in variability) in the soil seed bank, in relation to hydro-geomorphoic habitat (i.e., inundation and depth). Soils samples have been collected from both the proposed ‘inside’ and ‘outside’ region of wetlands, at three different inundation zones (wetland margins, mid zone and centre zone). This study will become a pilot exercise, with the view that once fencing is completed, soils can be again collected under test and control situations to examine implications on aquatic plant community. The results of this seed bank experiment will be completed in the TropWATER freshwater ecology laboratory, with the results presented in a separate report which will add further baseline data to this region. Figure 4.8

Wetland soils collected for seed bank germination trial (Photos Eric Vanderduys, CSIRO, 2015)

Methods that utilise photographic image processing and analysis packages are being used more regularly to examine coverage and extent of land features, in this case wetland plant coverage. During this field trip, a series of photographs were collected for many wetlands in the Archer River floodplain (including most of the wetlands surveyed here; Figure 4.9) for later processing in an attempt to examine wetland plant coverage and composition. This method continues to be further developed by CSIRO Land and Water, with the assistance of TropWATER, and will become an important tool to assess impacts of feral pig impact and fencing abatement as this program continues into the future.

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Figure 4.9

4.4

Wetland on Archer River floodplain photograph using video camera software (Photo provided by Justin Perry, CSIRO, 2015)

Continuing research and monitoring of wetland management

The value of coastal wetlands in terms of the ecosystem services provided to local species, the cultural values and amenity more broadly, means that these systems need management intervention to ensure they remain productive and viable habitat into the future. The data in the present study provides a preliminary look at these wetlands, and important data prior to the proposed fencing mitigation. While there is seemingly little differences in the data for the proposed “inside” and “outside” of fencing, this difference is likely to become more apparent in the future. The differences expected might well be as apparent as impacted and less impacted, or similarly, there might be little benefit with wetlands still becoming degraded as pigs can still access at least part of the wetland. At the least, the same survey completed here should continue into the future, so that it contributes to the generation of a long term database where species accumulation cures and population trends, along with water quality processes can be adequately assessed. Such long term datasets are rarely considered following wetland mitigation projects, and the success of mitigation is generally not known or possible. By implementing fencing that only restricts feral pig access to approximately half the wetland area is novel in its design and will generate useful data and discussion. There is now an apparent need to continue this monitoring, as the fencing is completed and to examine the efficacy of this mitigation approach in achieving wetland protection and species conservation (in addition to terrestrial communities that may also utilise these wetlands). Unlike other wetland fencing projects, where the entire wetland is fenced, the idea here is to still permit access to part of the wetland. This is a major limitation in exclusion programs elsewhere, in that fencing excludes access to the wetland resource entirely, particularly for larger terrestrial animals. Similarly, for aquatic animals within the fenced wetland, there are concerns that fencing prevents migration away from wetlands (animals become trapped in the wetland). As part of the on-going research and monitoring, there is a need to test the efficacy of fencing designs, to ensure that the design achieves the dual benefits of excluding access to wetlands by target feral species, but also still permits aquatic animals to migrate between wetlands and river channels. Such research could effectively result in the generation of best design guidelines for wetland fencing programs, which may require some local modification depending on the objectives of the project and local species. This end user outcome for wetland protection is critical, and necessary as more coastal floodplain wetlands in northern Australia continue to be impacted by feral animals. Page 43


The opportunity to continue developing local skills in wetland condition assessment and management should be further explored. The opportunity to share knowledge between western science and traditional owners continues to be a successful strategy to managing country in northern Australia. TropWATER has been working with traditional land owners throughout northern Australia and the Torres Straits for many years with many successful projects still continuing.

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5

REFERENCES

Allen, G.R., Midgley, S., Allen, M. (2002) Field guide to the freshwater fishes of Australia. CSIRO Publishing, Australia. Atlas of Living Australia (ALA) website at http://www.ala.org.au. Accessed 29 October 2010. Barrios-Garcia, M. N., Ballari, S. A. (2012). Impact of wild boar (Sus scrofa) in its introduced and native range: a review. Biological Invasions, 14, 2283-2300. Burrows, D., Butler, B. (2012) Preliminary studies of temperature regimes and temperature tolerance of aquatic fauna in freshwater habitats of northern Australia. Report 12/01. Australian Centre of Tropical Freshwater Research, James Cook University, Townsville, Australia. Butler, B., Burrows, D.W. (2007) Dissolved oxygen guidelines for freshwater habitats of northern Australia. Report 07/32. Australian Centre for Tropical Freshwater Research, James Cook University, Townsville, Australia. Cann, J. (1998) Australian freshwater turtles. Beumont Publishing, Singapore. 292pp. Chessman, B.C. (2003) New sensitivity grades for Australian river macroinvertebrates. Marine and Freshwater Research, 54, 95-103. Clarke, K. R., Gorley, R. N. (2001) PRIMER v5: user manual/tutorial. PRIMER-E Plymouth. Clarke, K.R., Warwick, R. M. (2001). A further biodiversity index applicable to species lists: variation in taxonomic distinctness. Marine Ecology Progress Series, 216, 265-278. Doupe, R. G., Mitchell, J., Knott, M. J., Davis, A. M., Lymbery, A. J. (2010) Efficacy of exclusion fencing to protect ephemeral floodplain lagoons habitats from feral pigs (Sus scrofa). Wetlands Ecol Manage, 18, 69-78. Doupe, R. G., Schaffer, J., Knott, M. J., Dicky, P. W. (2009). A Description of freshwater turtle habitat destruction by feral pigs in tropical northeastern Australia. Herpetological Conservation and Biology, 4(3), 331-339. Ferronato, B. O., Roe, J. H., Georges, A. (2014) Reptile bycatch in a pest-exclusion fence established for wildlife reintroductions. Journal for Nature Conservation, 22(6), 577-585. Fordham, D. A., Georges, A., Brook, B. W. (2007). Demographic response of snake‐necked turtles correlates with indigenous harvest and feral pig predation in tropical northern Australia. Journal of Animal Ecology, 76, 1231-1243. Freeman, A.B., Benham, B., Sebasio, D., Cann, J., Strevens, W. (2014) Summary of the rediscovery of the Jardine River turtle in Australia: Management implications and recommendations. Brisbane: Department of Environment and Heritage Protection, Queensland Government. Georges, A., Thomson, S. (2010) Diversity of Australasian freshwater turtles, with annotated synonymy and keys to species. Zootaxa 1-37. Georges, A., Guarino, F., Bito, B. (2006) Freshwater turtles of the TransFly region of Papua New Guinea–notes on diversity, distribution, reproduction, harvest and trade. Wildlife Research, 33(5), 373-384. Hamann, M., Schauble, C. S., Limpus, D. J., Emerick, S. P.,Limpus, C. J. (2007). Management plan for the conservation of Elseya sp. Burnett River) in the Burnett River catchment. Queensland Government Environment Protection Agency, Brisbane. Hamann, M., Schauble, C. S., Emerick, S. P., Limpus, D. J., Limpus, C. J. (2008) Freshwater turtle populations in the Burnett River. Memoirs of the Queensland Museum, 52, 221-232. Janzen, D.H. (1983) No park is an island: increase in interference from outside as park size decreases. Oikos 41:402–410. Kennett, R., Christian, K. (1994). Metabolic depression in estivating long-neck turtles (Chelodina rugosa). Physiological Zoology, 1087-1102. Kennett, R. (1996). Growth models for two species of freshwater turtle, Chelodina rugosa and Elseya dentata, from the wet-dry tropics of northern Australia. Herpetologica, 383-395. Page 45


Kennett, R. (1999). Reproduction of two species of freshwater turtle, Chelodina rugosa and Elseya dentata, from the wet–dry tropics of northern Australia. Journal of Zoology, 247, 457-473. Krull, C. R., Choquenot, D., Burns, B. R., Stanley, M. C. (2013). Feral pigs in a temperate rainforest ecosystem: disturbance and ecological impacts. Biological invasions, 15, 2193-2204. Last, P.R. (2002) Freshwater and estuarine elasmobranchs of Australia. In: Fowler SL, Reed TM and Dipper FA (eds) Elasmobranch Biodiversity, Conservation and Management. Proceedings of the International Seminar and Workshop, Sabah, Malaysia, IUCN Shark Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK, 185-193. Pearson, R.G., Crossland, M., Butler, B., Mansaring, S. (2003) Effects of cane-field drainage on the ecology of tropical waterways. Report on Sugar Research Development Corporation, James Cook University, Townsville Australian Centre for Tropical Freshwater Research (JCU016 & JCU024). Pettit, N. E., Jardine, T. D., Hamilton, S. K., Sinnamon, V., Valdez, D., Davies, P. M., Douglas, M. M., Bunn, S. E. (2012). Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes. Marine and Freshwater Research, 63, 788-800. Peverell, S.C. (2005). Distribution of sawfishes (Pristidae) in the Queensland Gulf of Carpenteria, Australia, with notes on sawfish ecology. Environmental Biology of Fishes 73, 391-402. DOI: 10.1007/s-10641-005-1599-8. Pogonoski, J.J., Pollard, D.A., Paxton, J.R. (2002) Conservation overview and action plan for Australian threatened and potentially threatened marine and estuarine fishes. Environment Australia, The Commonwealth of Australia. Primack, R.B. (1998). Essentials of Conservation Biology. Sinauer Associates, Sunderland, Massachusetts, USA. Pusey, B., Kennard, M., Arthington, A. (2004) Freshwater fishes of north-eastern Australia. CSIRO Publishing, Canberra. Reidy, M. M., Campbell, T. A., Hewitt, D. G (2008) Evaluation of electronic fencing to inhibat feral pig movements. J Wildl Manage 72, 1012-1017. Taniuchi, T., Schimizu, M., Sano, M., Baba, O., Last, P.R. (1991) Description of freshwater elasmobranchs collected from three rivers in northern Australia. University Museum, University of Tokyo, Nature and Culture 3, 11-26. Thomson, S. 2003. Distinguishing the Yellow Face Turtle and the Diamond Head Turtle. Emydura Tanybaraga and Emydura subglobosa worrelli. World Chelonian Trust. Thorburn, D.C., Peverell, S., Stevens, J.D., Last, P.R., Rowland, A.J. (2003) Status of freshwater and estuarine elasmobranchs in northern Australia. Australian Government, Natural Heritage Trust. Tierney, T. A., Cushman, J. H. (2006) Temporal changes in native and exotic vegetation and soil characteristics following disturbances by feral pigs in a California grassland. Biological Invasions 8, 1073-1089. University of Canberra Wildlife Tissue Collection Database at http://iae.canberra.edu.au/cgi-bin/locations.cgi. Accessed 24 November 2015. Wallace, J., Waltham, N., Burrows, D., McJannet, D. (2015) The temperature regimes of dryseason waterholes in tropical northern Australia: potential effects on fish refugia. Freshwater Science, 34, 663-678. Wallace, J., Waltham, N., Burrows, D. (In press) A comparison of temperature regimes in dry season waterholes in the Flinders and Gilbert catchments in northern Australia. Marine Freshwater Research, accepted March 2016. Waltham, N. J., Burrows, D. W., Butler, B., Wallace, J., Thomas, C., James, C., Brodie, J. (2013) Waterhole ecology in the Flinders and Gilbert catchments. A technical report to the Australian Government from the CSIRO Flinders and Gilbert Agricultural Resource Assessment, part of the North Queensland Irrigated Agriculture Strategy. CSIRO Water for a Healthy Country and Sustainable Agriculture flagships, Canberra, Australia. Page 46


Waltham, NJ, Butler B (2014) ‘Dugald River Project – Baseline Limnology Data Report (20122014)’, Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) Publication 14/15, James Cook University, Townsville, 93 pp. Waltham, N., Hughes, J., Davie, P., (2014). Freshwater crabs occupying tropical north Queensland coastal creeks. Australian Zoologist, 37(2), 256-262.

Page 47

3 1

4

1 1

2 2

9

9 15

1

3

3 1

1 1 14 1

1 2

4 41

1 1 4

4 3 14 2 2 1

8 2 6 8 6

3 2 1 1

1 4 21 18 9 7

4 2 1 2 2

1

8 4 4

12 3 2 13 1 6 6 2 4 9 6 22 18 8 36 21 31 34 8 11 18 17 8 14 8 8 9 5

1

1 1

4 2 1

4 2

2 2 4 3 3 2 3 1

2

1

1

2

4 3 1 4 3 5 4 1 6 5 1 2 2 3 5 1 7 6 7 2 6 6 6 6 1 6 2 3 4

Total

Sp Richness

Chelodina oblonga

Toxotes chartareus

Scleropages jardini

Porochilus rendahli

Oxeleotris selheimi

Oxeleotris lineolata

Mogurnda adspersa

Melanotaenia trifasciata

Melanotaenia s. inornata

Melanotaenia nigrans

Neosilurus ater

Nematolosa erebi

1 1 2 2

4 1 5

Leiopotherapon unicolor

Position Replicate Outside 1 Outside 2 Inside 1 Inside 2 Inside 3 Outside 1 Outside 2 Inside 1 Inside 2 Inside 3 Outside 1 Outside 2 Inside 1 Inside 2 Inside 3 Outside 1 Outside 3 Inside 1 Inside 2 Inside 3 Outside 1 Outside 2 Outside 3 Inside 1 Inside 2 Inside 1 Inside 2 Inside 3

Iriatherina werneri

Method BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV BRUV

Hypseleotris compressa

Date Site 27/06/2015 AR2 27/06/2015 AR2 27/06/2015 AR2 27/06/2015 AR2 27/06/2015 AR2 27/06/2015 AR3 27/06/2015 AR3 27/06/2015 AR3 27/06/2015 AR3 27/06/2015 AR3 27/06/2015 AR4 27/06/2015 AR4 27/06/2015 AR4 27/06/2015 AR4 27/06/2015 AR4 27/06/2015 AR5 27/06/2015 AR5 28/06/2015 AR5 28/06/2015 AR5 28/06/2015 AR5 28/06/2015 AR6 28/06/2015 AR6 28/06/2015 AR6 28/06/2015 AR6 28/06/2015 AR6 30/06/2015 K1 30/06/2015 K1 30/06/2015 K1

Glossamia aprion

Freshwater fish counts using baited underwater video cameras (BRUVs)

Craterocephalus stercusmuscarum

A.1

Amnitaba percoides

APPENDICES

Ambassis sp.

A

Strongylura krefftii


20 5 2 17 7 20 27 2 20 14 6 36 19 13 86 21 43 54 19 13 37 52 41 40 27 10 16 9

Page 48


Dugesiidae

Leptoceridae

Hydroptilidae

Ecnomidae

Ostracoda

Oligochaeta

Macromiidae

Libellulidae

HUL complex

Gomphidae

Coenagrionidae

Hydridae

Pleidae

Notonectidae

Nepidae

Naucoridae

Mesoveliidae

Corixidae

Belostomatidae

Planorbidae

Lymnaeidae

Caenidae

Baetidae

Tanypodinae

Tabanidae

Culicidae

Chironominae

Chaoboridae

Ceratopogonidae

Parathelphusidae

Parastacidae

Copepoda

Conchostraca

Noteridae

Hygrobiidae

Hydrophilidae

Hydrochidae

Haliplidae

Gyrinidae

Habitat Pool Bottom 2 84 0 Macrophyte 4 21 0 Pool Bottom 3 11 0 Macrophyte 0 7 0 Pool Bottom 0 9 0 Macrophyte 9 30 0 Pool Bottom 5 16 0 Macrophyte 13 41 0 Pool Bottom 0 6 1 Macrophyte 17 47 0 Pool Bottom 0 20 0 Macrophyte 5 51 0 Pool Bottom 0 2 0 Macrophyte 1 14 0 Pool Bottom 2 2 0 Macrophyte 3 3 0 Pool Bottom 0 0 0 Macrophyte 2 3 0 Pool Bottom 0 1 0 Macrophyte 2 14 0 Pool Bottom 11 12 0 Macrophyte 31 13 0 Pool Bottom 14 8 0 Macrophyte 10 0 0 Total 134 415 1 Occurrence 0.71 0.92 0.04

Dytiscidae

Curculionidae

Cladocera

Site AR2_out AR2_out AR2_in AR2_in AR3_out AR3_out AR3_in AR3_in AR4_out AR4_out AR4_in AR4_in AR5_out AR5_out AR5_in AR5_in AR6_out AR6_out AR6_in AR6_in K1 K1 K2 K2

Aquatic macroinvertebrates

Acarina

A.2

6 0 4 0 0 0 0 3 33 11 0 1 0 37 0 0 6 12 0 0 1 0 45 0 0 0 2 0 0 8 0 8 7 0 13 7 0 0 1 0 12 0 1 0 0 0 0 22 20 0 0 0 0 13 1 0 11 34 0 0 0 4 36 0 1 3 0 0 0 4 0 25 21 0 18 49 0 0 0 2 9 0 6 0 0 0 0 2 3 7 0 1 0 11 0 0 2 7 0 0 0 0 27 0 0 0 1 0 0 1 1 2 4 0 8 4 0 0 0 1 19 0 0 1 1 0 2 13 9 0 0 1 0 7 3 0 4 20 2 0 0 3 22 0 0 3 0 8 0 5 0 22 10 0 12 31 0 0 0 0 25 0 0 0 0 0 0 1 1 3 0 0 0 16 0 0 2 0 0 0 0 6 2 0 0 0 0 0 0 0 1 0 5 0 0 0 1 0 0 0 8 0 13 0 0 2 0 0 14 0 0 5 0 33 0 0 5 7 0 0 0 4 2 2 0 5 0 1 0 14 0 11 3 2 17 5 0 0 0 0 13 0 1 0 0 0 0 0 49 5 0 2 0 3 0 0 3 2 1 0 0 0 20 0 0 0 0 1 0 4 0 1 7 0 0 5 0 0 3 0 19 0 0 0 2 0 0 1 24 2 0 0 0 10 4 0 6 32 1 0 0 4 4 0 0 3 1 11 0 20 0 12 4 0 9 17 0 0 3 0 26 1 2 0 0 0 0 1 2 8 0 2 0 22 6 0 9 7 0 0 1 38 3 0 4 2 0 10 14 34 0 6 11 0 14 1 0 0 0 1 6 0 0 0 1 0 0 0 17 1 0 1 0 65 2 0 9 103 0 0 0 10 10 0 14 10 2 0 7 34 0 22 31 0 21 43 0 1 0 1 10 2 0 2 2 0 0 0 4 7 0 0 0 34 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 5 0 1 0 0 0 0 0 19 0 1 2 1 0 0 4 17 1 0 3 0 9 8 0 7 38 0 0 1 9 0 0 11 4 4 14 0 26 0 15 14 0 16 7 0 0 0 0 5 0 0 0 0 0 0 0 2 3 0 0 0 26 0 0 0 0 0 0 0 0 7 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 26 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 0 0 0 0 0 0 0 0 0 0 0 0 0 6 0 3 0 0 0 0 1 6 7 0 1 0 33 0 0 14 1 0 0 0 0 24 0 0 0 0 0 0 2 0 0 8 0 1 6 2 0 0 0 7 0 0 12 0 0 0 2 2 0 0 0 0 13 1 0 8 29 0 0 0 4 6 0 12 11 1 18 0 27 0 16 11 0 5 18 0 0 6 0 13 0 1 0 0 0 0 0 0 4 0 0 0 16 0 0 0 2 0 0 0 1 1 0 0 1 0 2 0 0 0 3 0 0 1 0 0 0 0 0 1 0 3 0 0 0 0 0 2 1 0 0 0 1 0 0 2 2 0 0 0 1 0 0 0 1 0 0 0 0 0 12 2 0 0 4 0 0 0 0 13 0 1 0 1 0 0 0 0 1 0 0 0 12 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 33 0 0 4 5 0 0 0 7 1 0 0 0 6 4 0 3 4 0 0 0 1 0 0 4 1 0 16 0 8 0 8 3 0 2 12 0 0 0 0 11 0 0 5 1 0 0 0 25 0 0 3 0 3 3 1 7 22 1 1 0 29 0 0 4 0 0 6 0 30 0 50 11 0 5 3 0 0 0 0 7 0 1 0 0 0 0 0 11 0 0 1 0 0 0 0 0 5 0 0 0 2 0 0 0 1 0 6 0 17 0 17 11 0 7 2 0 0 0 0 10 0 0 11 2 0 0 0 74 0 2 2 0 10 2 0 8 18 1 3 12 14 0 0 12 6 1 5 0 52 0 16 17 0 9 12 0 0 0 0 4 0 0 1 3 0 0 3 25 0 0 1 37 4 0 0 0 10 0 1 4 1 0 0 8 4 0 1 0 15 0 3 1 0 5 1 0 0 0 0 308 3 37 38 20 2 2 53 347 62 2 24 37 384 34 1 108 355 6 5 19 132 209 2 70 55 12 99 21 302 2 250 186 2 164 229 3 1 13 5 1 0.08 0.5 0.33 0.46 0.04 0.004 0.46 0.88 0.63 0.04 0.54 0.04 0.92 0.42 0.04 0.79 0.79 0.21 0.13 0.21 0.71 0.58 0.04 0.38 0.58 0.29 0.54 0.08 0.75 0.08 0.83 0.83 0.04 0.75 0.79 0.08 0.04 0.17 0.17

Page 49


A.3

Freshwater turtles

Date River Site 25/06/2015 Archer River Wetlands AR3

Position outside

Species C. oblonga

Sex f

SCL 276

SCW 196.9

PL 207.6

PW 105.7

HL 79.4

HW 49.6

TL 65.6

Weight (g) 3100

25/06/2015 Archer River Wetlands AR3

outside

C. oblonga

m

253.4

191.9

188.9

97.6

68.7

46.2

58.1

2250


outside

C. oblonga

m

250.8

180.9

191.3

99.7

72.2

44.1

56.5

2400

26/06/2015 Archer River wetlands AR3

inside

E. s. worrelli

f

276.9

214.8

219.7

84.4

68.9

52.9

88.9

2850


inside

E. s. worrelli

f

225.5

184

173.5

66.6

52.4

39.7

51.6

1450


outside

E. s. worrelli

f

276.5

220.3

216.7

83.8

61.5

46.3

70.7

2700


outside

C. oblonga

m

268.8

194.1

207.7

108.2

75.1

45.2

53.9

2950


outside

E. s. worrelli

m

242.8

177.8

182.4

68.5

57.5

41.9

112.8

1700


inside

C. oblonga

f

354.9

245.9

267.8

139.7

89.6

63.8

89.9

6700


inside

C. oblonga

f

310.8

201.1

235.6

119.8

85.9

56.1

71

4000

1/07/2015

Kalan Wetlands

K1

inside

C. oblonga

m

193

134

150

70

53

39

56

NA

1/07/2015

Kalan Wetlands

K1

inside

C. oblonga

m

221

143

270

82

59

40

61

NA

1/07/2015

Kalan Wetlands

K1

inside

C. oblonga

juv

151

109

117

59

42

30

23

NA

1/07/2015

Kalan Wetlands

K1

inside

C. oblonga

juv

139

100

110

55

48

29

38

NA

1/07/2015

Kalan Wetlands

K1

inside

C. oblonga

m

216

156

171

88

68

43

55

NA

1/07/2015

Kalan Wetlands

K1

inside

C. oblonga

juv

161

113

126

63

47

31

30

NA

1/07/2015

Kalan Wetlands

K1

inside

E. s. worrelli

f

187

147

144

55

41

30

46

NA

Page 50


Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) ATSIP Building James Cook University Townsville Qld 4811 Phone: Fax: Email: Web:

07 4781 4262 07 4781 5589 [email protected] www.jcu.edu.au/tropwater/

Page 51