Gladstone Ports Corporation Report for Marine Megafauna and Acoustic Survey. Autumn Survey

Transcription

1 Gladstone Ports Corporation Report for Marine Megafauna and Acoustic Survey November 2011

2 Contents Acronyms and Abbreviations... v Executive Summary... vi 1. Introduction Marine Megafauna Survey Study Area Survey Schedule Marine Megafauna Boat-based Observations Aerial Surveys Acoustic Monitoring Survey Results Overview Boat-based Surveys Aerial surveys Study Area Environmental Parameters Marine Acoustic Results and Analysis Acoustic Survey Comparisons Marine Megafauna Habitat Utilisation Discussion Survey Coverage and Adequacy Marine Megafauna Abundance and Distribution Impacts Potentially Associated with the Western Basin Dredging Project and Other Development in the Study Area Conclusion and Recommendations References Table Index Table 2-1 Schedule aerial and boat-based marine megafauna survey completed in i

3 Table 2-2 Indicative age class categories for green turtle, dugong and inshore dolphins... 9 Table 2-3 Beaufort scale Table 2-4 Turbidity scale Table 3-2 Table 3-3 Table 3-4 Number of marine megafauna sightings during both boat-based surveys Average values for turbidity, glare and Beaufort sea state for both survey events Summary of marine megafauna observations during summer and autumn aerial surveys Figure Index Figure 2-1 Location of boat-based transects... 4 Figure 2-2 Boat-based survey sites overlayed with seagrass habitat mapping by Rasheed et al Figure 2-3 Aerial transect locations Figure 2-4 Reson TC4032 hydrophones each with a 50 m cable attached Figure 2-5 Figure 3-1 Buoys supporting the deployment of the two hydrophones from the survey vessel All boat-based and aerial observations of marine fauna during the project Figure 3-2 Age class frequency of marine megafauna observations Figure 3-3 All boat-based sightings June, Figure 3-4 Indo-Pacific humpback dolphin jumping in Port Curtis Figure 3-5 Indo-Pacific humpback dolphin playing with a strap of algae Figure 3-6 Indo-Pacific humpback dolphins observed during boat-based survey23 Figure 3-7 A group of snubfin dolphins observed in Port Alma Figure 3-8 Group size and age class for snubfin dolphins observed during both survey events Figure 3-9 Inshore bottlenose dolphin observed north of Curtis Island Figure 3-10 Age class and location of green turtles observed during both survey events Figure 3-11 Location and frequency of turtle observations (unidentified species) 27 Figure 3-12 Comparison of survey observations between years in Port Curtis Figure 3-13 Observed frequency of Indo-Pacific humpback dolphins Figure 3-14 Observed frequency of dugong Figure 3-15 Location and tidal state for all turtle observations during aerial surveys ii

4 Figure 3-16 All aerial survey observations for high and low tide periods for surveys 1 (Feb/Mar) and 2 (June) combined Figure 3-17 All aerial survey observations for surveys 1 (Feb/Mar) and 2 (June). 35 Figure 3-18 Figure 3-19 Figure 3-20 Average depth recorded during surveys - Error bars represent standard error (s.e.) Average temperature recorded at survey localities - Error bars represent standard error (s.e.) Average turbidity at survey localities - Error bars represent Standard Error (s.e.) Figure 3-21 Average salinity values recorded during survey events Figure 3-22 Bio-sonar of snubfin dolphin ~15 m from hydrophone Figure 3-23 Brief whistle of a snubfin dolphin circled in yellow Figure 3-24 Figure 3-25 Spectrogram of a passing tinny (left) and a passing water jet ferry (right) Photos of common vessels in Port Curtis; a water jet ferry (top), small personnel ferry (middle) and a bulk carrier being pushed by two unseen tugs (bottom) Figure 3-26 Comparison between background noise and the noise of a tinny Figure 3-27 Frequency ranges of some common fauna and port activities Figure 3-28 Spectrogram of a passing tinny Figure 3-29 Spectrogram of a passing ferry near the ship loadout wharf Figure 3-30 Comparison between survey 1 and 2, overall SPL measurements Figure 3-31 Comparison between survey 1 and 2, mid frequency cetacean SPL levels Figure 3-32 Comparison between survey 1 and 2, turtle SPL levels Figure 3-33 Figure 3-34 Figure 3-35 Figure 3-36 Figure 4-1 Figure 4-2 Figure 4-3 Marine megafauna observations and average depth at sampling locations Marine megafauna observations and average temperature at sampling locations Marine megafauna observations and average turbidity at sampling locations Marine megafauna observations and average salinity at sampling locations Marine turtle nesting frequency for Curtis Island and Woongarra Coast, Bund wall and associated lighting; dredgers and barges in the background Indo-Pacific humpback dolphins observed in the early evening at Port Curtis Figure 4-4 Jet skis travelling through the Narrows iii

5 Figure 4-5 Total registered vessels within the Gladstone Regional Council Appendices A Weather Conditions B Transects and Spot Sample Sites C Boat-based Marine Megafauna Observations D Environmental Parameters Measured During Boat-based Observations E Weather Conditions During Aerial Surveys F Marine Megafauna Observations During Aerial Surveys G Environmental Parameters Measured During Marine Megafauna Observations H Potential Biological Removal I Acoustic Survey Values for March and June iv

6 Acronyms and Abbreviations CG CPA DAQ db DEEDI DERM EPA GBRMPA GPCL GPS Hz khz L-f LNG ms M M-f µpa n Pa. 2 S RMS SD s.e. SNR SPL WBDDP Coordinator General Closest Point of Approach Data Acquisition Device Decibel Department of Employment, Economic Development and Innovation Department of Environment and Resource Management Environmental Protection Agency Great Barrier Reef Marine Park Authority Gladstone Ports Corporation Limited Global Positioning System Hertz Kilohertz Low Frequency Liquefied Natural Gas Milliseconds Metre Mid Frequency Micropascal Number of Pascal Squared x Seconds Root Mean Square Standard Deviation Standard Error Signal to Noise Ratio Sound Pressure Level Western Basin Dredging and Disposal Project v

7 Executive Summary The region between Port Cutis and Port Alma currently supports a range of coastal development activities and additional significant projects are proposed or are under construction in the region. The Western Basin Dredging and Disposal Project (WBDDP) was approved by the Coordinator-General in July Conditions of Approval for the WBDDP include a requirement to collect baseline information on the marine megafauna species between Port Alma, Port Curtis and Rodds Peninsula; the Curtis Coast Region. GHD have completed a survey program on behalf of Gladstone Ports Corporation Limited (GPCL) which provides baseline information in accordance with the some of the project approval conditions. The information from this baseline program will be used to further develop the scope and program for future monitoring and research events over the next ten years. This report presents the combined results of the surveys completed during the program, including data from aerial and boat-based marine megafauna observations and a marine acoustic assessment. Additionally, the GPCL scope of works required monitoring on the effect of port development activities which may potentially affect marine megafauna. The summer survey events were conducted in February/March 2011 (boat-based) and April 2011 (aerial) and the second, winter survey events were conducted back to back in June, The purpose of these surveys was to develop greater understanding of marine megafauna populations and movements within the study area over these times. The information from these initial surveys will be used to further develop the scope and program for future monitoring and research events over the next ten years. Marine Megafauna Observations Marine megafauna boat-based sightings for the project duration (n=201) comprised of 124 dolphins (Indo-Pacific humpback, Australian snubfin and inshore bottlenose dolphins), three dugong, 68 turtles (green, hawksbill, and loggerhead turtles) and six seasnakes. Aerial observations from combined surveys (both tides and seasons; n= 180) comprised of 57 dolphins, 11 dugong, 79 turtles, two seasnakes, four sharks and 27 rays. Marine fauna were observed to occur in association with recreational vessel traffic, which was widespread throughout much of the survey area, particularly in the Narrows and Port Curtis. Dolphins were observed to be present in association with anthropogenic activities such as commercial fishing, slow shipping movements, ferries used for transporting construction crews and adjacent (west) to the Curtis Island development site. In these areas, turtles were observed near jet skis and small tinnies and dugong were observed near frequent recreational vessel movement (Pelican Banks and South End, Curtis Island). Marine fauna species were not recorded in the presence of pile driving or rock dumping activity. Dredging was not being undertaken whilst the surveys were occurring. The average group size of Indo-Pacific humpback dolphins observed on boat-based surveys was 3.5 individuals (s.d. = 2.65), with the majority of groups sighted in the Port Curtis region. During the project, Indo-Pacific humpback dolphins were sighted in all survey regions. Indo-Pacific humpback dolphins were the most frequently observed species on boat-based surveys with 25 groups comprising 85 sightings. A total of 34 snubfin dolphins were observed during the boat-based surveys with all snubfin dolphin groups (n=8) being sighted in Port Alma and to the north of Curtis Island (adjacent to Port Alma). Two inshore bottlenose dolphins were observed north of Curtis Island. vi

8 Three adult dugongs were sighted near Pelican Banks (Port Curtis near southern Curtis Island) whilst undertaking boat-based surveys. More dugongs were observed during aerial surveys (n=10), including a mother and calf pair however, numbers were generally low for the region. The Pelican Banks area has been reported by DEEDI to support some of the remaining seagrass in Port Curtis. Marine turtles were sighted in all survey zones during the monitoring program, though their presence in these zones was not consistent between surveys. Of the observed green turtles, 17% were adults and 83% subadults. Two hawksbill turtles (one adult and one sub adult) were sighted on the seaward side of Facing Island, in association with numerous other turtles during the first survey period only. Four loggerhead turtles were sighted (all adults); one in Rodds Bay and two on the seaward side of Facing Island and one within Port Curtis. Two unidentified sub-adult turtles were observed in Port Alma during the survey. A total of six seasnakes were sighted during boat-based surveys where one was observed in Port Alma, one on the eastern side of Curtis Island and four in the Narrows. Rays and sharks were observed in shallow, clear waters in the southern area of the survey area and at the north eastern tip of Curtis Island amongst shallow intertidal flats. Relationships between observed frequency of megafauna species presence and environmental parameters (e.g. depth, turbidity) were not apparent. This may suggest that sufficient or appropriate measurement of relevant abiotic parameters has not been achieved. The highest frequency of sightings (n=162) for unit of effort was recorded during the June low tide aerial survey with the majority of observations being comprised of turtles (n= 49) and dolphins (n=41). The timing of surveys (following a prolonged wet season) is likely to have affected the detectability of marine fauna species given the generally high levels of turbidity throughout the survey area. Recorded observations are therefore likely to represent a conservative estimate of what species may actually be present during surveys, particularly aerial surveys where this is likely to have a greater influence on species detection. Reduced turbidity during the second aerial survey enabled observations to greater depths into the water column and in shallow areas, to the benthos. Numerous rays in the second aerial survey (n=26) were observed on the seabed whereas only one was observed in the first survey event. Some density change in species was detected between aerial surveys with an increase in sightings of turtle, dugong and Indo-Pacific humpback and snubfin dolphins. Changes were most notable in the southern region of the survey area in Rodds Bay and Port Curtis. Using species presence as a surrogate measure of habitat importance, the survey region is determined to be of conservation importance. With all observational survey data combined, varying densities of marine fauna become apparent within the survey zones. The survey regions were divided with consideration of ecology to be managed as five zones which included: Port Alma, Eastern Curtis/Facing Islands, The Narrows, Port Curtis and Rodd s Bay. There are key areas within the survey region which are considered to be of high value in a regional context and these are comparable to the observations recorded for the WBDDP EIS. Each area surveyed has consistently demonstrated high species presence and prevalence suggesting they are of importance. Marine fauna were not observed to occur within the immediate coastal construction sites adjacent to Curtis Island however, they were observed to be present (in low numbers) near the recently developed bund wall and barge landing facility in Graham s Creek, as per surveys prior to development. The area north east of the Calliope River and south of Graham Creek is undergoing intensive change due to infrastructure development. This area was found to have reduced presence of marine turtle, dugong and vii

9 dolphin compared to earlier surveys undertaken for the WBDDP suggesting an indirect impact of habitat displacement has likely occurred. The reduced species presence can in part be attributed to the reported loss of seagrass; however, the presence of inshore dolphins is not strongly associated with this benthic habitat community and they too have been observed with reduced presence in this area. Other factors such as increased background noise levels and vessel traffic may have displaced some species such as turtle, dugong and dolphin from the formerly frequented area. Marine Acoustic Assessment To develop an understanding of potential noise impacts on marine megafauna species, background ambient noise measurements were recorded across the same sample sites in both summer and autumn surveys. During these events, measurements were collected across four time periods each day. Additionally, opportunistic samples of underwater noise conditions derived from anthropogenic sources were also recorded during the survey program. These ambient noise levels were observed to vary between locations in addition to different time periods of a day and between survey events. Anthropogenic noises (i.e. pile driving and vessel movements) were notably higher than the background noise for all areas at all times of the day. Anthropogenic noise (as measured) is considered to be audible by all species at the ranges measured. An acoustic model was used to approximate the distance at which pile driving and bulk carrier noise (from source) would be lower than ambient noise level. This distance was over 4 km for pile pulses (estimated to be closer to between 15 to 20 km) while for bulk carrier-generated noise it was predicted to be between 1.3 km and 4 km. It must be noted that this is not an indication of the extent of impacts but a reference for where noise attenuated to background conditions. Data were analysed to consider what distance from a given noise source would result in impact to cetaceans under differing exposure levels. In doing so, this assumes a conservative scenario whereby cetaceans would maintain a stationary position at a set distance from the noise source. This data is summarised in Table E1 for cetaceans, whereby the red cell indicates possible physical injury and a yellow cell indicates a temporary threshold shift. This table indicates that at a distance of 200 m, temporary affects would be experienced by a cetacean after an hour of exposure and permanent affects would be experienced at a distance of 100 m after 10 minutes of pile driving. viii

10 Table E1 Distance from source and exposure time for permanent and temporary effects Received SEL (db re 1µPa 2.S) in the duration of Range, km Single pile (~90 ms) 10 s 10 m 0.5 h 1 h 3 h The Gladstone Port Alma region is currently subject to the cumulative pressures of naturally driven extensive habitat loss and intensive coastal development, which is not dissimilar from much of the Queensland coast. The monitoring surveys herein broaden the understanding of species utilising the region. Ideally, future studies would aim to have more detailed data collected on species movements and habitat use through a combination of means that not only provide a snap shot in time, as achieved by the surveys reported here, but continued monitoring over time given their inherent vulnerability to decline. Telemetry and passive acoustic studies are used to further inform the ecological responses of marine fauna species and these could potentially be implemented within this region to determine potential and real-time impacts on species. Population estimates have previously been determined for coastal dugong populations (Marsh and Lawler 2006), nesting turtles of Curtis and Peak Island (Limpus 2007), snubfin and Indo-Pacific humpback dolphins (Cagnazzi 2011) these populations require continued monitoring effort to detect changes at the population level and at an ecological scale. Population estimates are required for foraging turtles within the project area for which future monitoring can refer to. The current state of the Gladstone coastal environment should not be considered a baseline reference given the rapid change that has occurred since the WBDDP EIS was undertaken in As impacts to marine fauna populations in the survey region are considered to continue into the near future, these monitoring activities are advised to be undertaken sooner rather than later. Research activities implemented in conjunction with regional mitigation strategies for consistency in response to construction impacts will go some way to improving the conservation outcome of marine megafauna in this region. Conclusion The megafauna surveys address the conditions described in the contract Scope of Works, as detailed below. Determine baseline population characteristics and habitat utilisation ix

11 Boat based and aerial observations from all surveys reported a total of 181 dolphins, 14 dugong, 137 turtles, 8 snakes, 4 sharks and 27 rays throughout the survey area. Densities and age class of each species was investigated throughout the survey area. The survey regions were divided into five zones: Port Alma, Eastern Curtis/Facing Islands, The Narrows, Port Curtis and Rodds Bay. Rodds Bay and Port Curtis reported the greatest number of megafauna observations over the monitoring period. Inform decisions on appropriate indicators to monitor potential for changes related to the dredging project Future studies should aim to include telemetry, passive acoustic studies and visual observation for monitoring potential and real-time impacts on species. Determine carrying capacity of nearby suitable habitats for marine megafauna species Determination of the carrying capacity of the habitats within the survey area was not able to be achieved. This was discussed with and agreed to be acceptable by the Technical Advisory Panel, in consultation with GPC, upon project inception. Determine utilisation significance of The Narrows for marine megafauna and what effects the project may have on utilisation of this area The survey area was divided into five zones, one of which was The Narrows. This region supported Indopacific dolphins, green turtles and seasnakes. In comparison with other zones, The Narrows recorded fewer megafauna observations, and fewer species. The region did not contain species that were not seen in other zones. The Narrows may facilitate interchange between populations of Indo-pacific dolphins in Port Curtis and Port Alma. Include a minimum of 50 fixed monitoring locations will occur throughout the study area with at least 10 of those at localities immediately impacted by the reclamation area including the embayment immediately north of the reclamation area Boat based surveys included 35 transect and 79 spot sample sites, and aerial surveys included 27 transect lines. Within the immediate vicinity of the reclamation area, the survey plan included 3 aerial transects, 3 boat based transects, and 9 boat-based spot sample sites. The design of the survey is considered to satisfy the requirements of the contract Scope of Works. x

12 1. Introduction The region between Port Cutis and Port Alma currently supports a range of coastal development activities with other significant projects proposed for the region. In July 2010, The Western Basin Dredging and Disposal Project (WBDDP) proposed for Port Curtis was approved under a bilateral process. The project comprises dredging associated with the deepening and widening of existing channels and swing basins and creating new channels, swing basins, berth pockets and a 200 ha reclamation area. The dredged material will be placed into the reclamation area to create a land reserve that will be utilised in part to service new port facilities. The dredging works will facilitate shipping access to, primarily, an LNG precinct on southern Curtis Island (currently under construction). The environmental impacts predicted from the WBDDP have been considered and conditions have been issued to the Gladstone Ports Corporation Limited (GPCL) from the CG. Conditions of Approval for the WBDDP project include a requirement to collect baseline information on the marine megafauna species between Port Alma, Port Curtis and Rodds Peninsula; the Curtis Coast Region. GHD have completed a survey program on behalf of GPCL which provides baseline information in accordance with most of the project s conditions. The survey monitoring program includes two sample periods, summer (February/March and April) and autumn (June). The objectives of the program of works were: Develop greater understanding of marine megafauna populations and movements within the study area over the prescribed survey times Determine baseline population characteristics (e.g. densities, reproductive capacity, age- class structure) and habitat utilisation Inform decisions on appropriate indicators to monitor potential for changes related to the dredging project Determine the utilisation significance of the Narrows for marine megafauna and what effects the project may have on utilisation of this area These objectives have been considered in the context of port development activities which may affect marine megafauna species. Observations of activities in the port environment recorded on survey that could affect megafauna presence and prevalence include: Pile driving Bund wall construction Noise impulse levels Light spill Water quality Vessel activity, and other relevant observations This report details results from the surveys completed, which included boat-based observations, aerial surveys and a marine acoustic assessment. The team who completed works for this survey and report are as follows: Rachel Groom (GHD), marine megafauna field work and technical reporting 1

13 Dr Isabel Beasley (Orcaella Consultancy), marine megafauna field work and technical reporting Granger Bennett (SVT), marine acoustic technical review Josh Berry (SVT), marine acoustic field work and technical reporting Binghui Li (SVT), marine acoustic field work and technical reporting Dr Kerry Neil (GHD), project management and review The results of marine megafauna observations have been delivered in two reports. The Marine Megafauna and Acoustic Monitoring Report - Summer Survey (GHD 2011) reports the results of boatbased megafauna observations during February/March. Literature reviews were conducted prior to the summer surveys to inform survey approach and reporting and the results of these are detailed in the Summer Survey report (GHD 2011). Policy and legislative context relevant to this project is also discussed in detail in the Summer Survey Report (GHD 2011). The current report presents the results of autumn surveys (both boat-based and aerial) and summer aerial surveys and compares findings with those reported from the summer boat-based survey and earlier understandings of megafauna within the study area. The Western Basin Dredging and Disposal Project is within the Great Barrier Reef World Heritage Area (GBRWHA) and is adjacent to the Great Barrier Reef Marine Park (GBRMP), Central Queensland. The Gladstone region has extensive industry spanning the coastline north and south of Port Curtis as well as within the area adjacent to the Project. More industry is proposed for development within the study area in coming years. The Summer Survey Report (GHD 2011) for this project detailed marine megafauna species observed to occur within the region and referenced seagrass habitats as surveyed by the Department of Employment, Economic Development and Innovation (DEEDI). The most recent seagrass surveys undertaken by DEEDI in 2011 have not yet been fully analysed however, there has been a significant reduction in seagrass biomass from the 2009 to 2010 monitoring surveys. One of the largest years, since annual surveys began in 2002, of abundance and distribution for seagrasses was recorded in the port in Trends in the seagrass distribution data from February and March 2011 (Sankey and Rasheed 2011) and personal observations show a much reduced presence of seagrass in the majority of meadows surveyed (pers. comm K. Chartrand, DEEDI, 2011). The extended wet seasons in early and late 2010 and flooding of the Fitzroy River have likely contributed to these reductions in seagrass habitat. Reported losses of seagrass from the study area is considered to have been significant despite the recent discovery of viable seagrass seed-banks within the project area (pers. comm. M. Rasheed, DEEDI, 2011). 2

14 2. Marine Megafauna Survey Field surveys for marine megafauna (turtles, dugong, and cetaceans (whales and dolphins)) were designed to address the following objectives: Determine baseline population characteristics (eg. densities, age-class structure, and habitat utilisation Determination of regional habitat use by marine megafauna species, with linkages to food chain dynamics Determine the utilisation significance of the Narrows for marine megafauna and what effects the project may have on utilisation of this area Consideration of changes in seasons and inter-annual changes 2.1 Study Area The study area extended from the Fitzroy River entrance (Port Alma) to the southern region of Rodds Bay, encompassing eastern Curtis and Facing Islands, and the entirety of Port Curtis and the Narrows (Figure 2-1). Sampling sites within the study area were selected to achieve representation of the various marine environments within the study area that are likely to support marine megafauna species. The study area is broad and covers environments that have varying levels of anthropogenic influence (e.g. construction, fishing and vessel activity) and diverse ecological values. Subsequently, five zones that generally reflect these differences were established: Port Alma Narrows Port Curtis Rodds Bay Eastern Curtis/Facing Islands 3

15 7,415, , , ,000 ROCKHAMP TON - EMU PARK ROAD 265, , , , , , , , , , , , , , , , , , , , , , , ,000 7,415,000 7,365,000 7,370,000 7,375,000 7,380,000 7,385,000 7,390,000 7,395,000 7,400,000 7,405,000 7,410,000 BAJOOL - PORT ALMA ROA D Port Alma BRUCE HIGHWAY Narrows TARGINIE ROAD Eastern Curtis/Facing Islands 25 See Inset PORT C URTIS WAY Inset KANGAROO ISLAND THE NARROWS Friend Point Laird Point PORT C URTIS WAY GRAHAM CREEK CURTIS ISLAND PORT CURTIS ,365,000 7,370,000 7,375,000 7,380,000 7,385,000 7,390,000 7,395,000 7,400,000 7,405,000 7,410,000 7,360, ,360,000 7,355,000 Port Curtis 20 7,355,000 7,350,000 7,345,000 DAWSON HIGHWAY BOYNE ISLAND ROAD TANNUM SANDS ROAD ,350,000 7,345,000 7,340,000 Rodd's Bay 7,340,000 7,335, , , , , , , , , , , , , , , , , , , , , , , , , , , ,000 7,335,000 1:350,000 (at A3) Kilometres Map Projection: Universal Transverse Mercator Horizontal Datum: Geocentric Datum of Australia Grid: Map Grid of Australia 1994, Zone 56 o Survey Points (Feb /Mar/June 2011) Gladstone Transect Lines Zoning Rodd's Bay Port Curtis Path: G:\41\23667\GIS\Maps\Working\41_23667_006_Survey Sites_Zoning_rev_b.mxd While GHD has taken care to ensure the accuracy of this product, GHD and GA make no representations or warranties about its accuracy, completeness or suitability for any particular purpose. GHD and GA cannot accept liability of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred as a result of the product being inaccurate, incomplete or unsuitable in any way and for any reason. Data source: GHD; Survey transect Points, Transects Lines, Zoning/2011 GA; Ocean, Roads, Railway, Coastal Boundaries/2011 Created by: MS Narrows Port Alma Eastern Curtis/Facing Islands Port of Gladstone Western Basin Dredging and Disposal Project Job Number Revision Date B 14 July 2011 Location of boat-based transects Figure 2-1 Level Charlotte Street Brisbane QLD 4000 Australia T F E bn @ghd.com W

16 2.2 Survey Schedule The summer boat-based survey (Survey 1) was undertaken over six days during a neap tide cycle that transitioned into a spring cycle between 27 February and 4 March 2011 (Table 2-1). Weather was suitable for surveying during most of the six day period with winds remaining < 12 knots and occasional showers postponing some sampling time on the last day of survey. The summer aerial survey was conducted on April 21; this event was postponed as weather conditions deteriorated following boatbased survey during March. The autumn boat-based survey (Survey 2) was undertaken over six days, from June 14 19, 2011, during a spring tide cycle. Weather remained clear, with Beaufort scale ranging from 1 to 3. The autumn aerial survey was conducted on June 13, immediately prior to boat-based survey. Table 2-1 Schedule aerial and boat-based marine megafauna survey completed in 2011 Date Survey type Survey Location Summer Survey 27 February Boat-based survey Port Curtis; Rodds Bay 28 February Boat-based survey Port Curtis; Eastern Curtis/Facing Islands 1 March Boat-based survey Eastern Curtis Island; Port Alma 2 March Boat-based survey Port Alma; Upper Narrows 3 March Boat-based survey Narrows; Port Curtis 4 March Boat-based survey Port Curtis 21 April Aerial Survey Entire study area: survey at high tide (AM) and survey at low tide (PM) 13 June Aerial Survey Entire study area: survey at high tide (AM) and survey at low tide (PM) 14 June Boat-based survey Port Curtis; Rodds Bay 15 June Boat-based survey Rodds Bay; Eastern Curtis/Facing Islands 16 June Boat-based survey Eastern Curtis/Facing Islands; Port Alma 17 June Boat-based survey Port Alma 18 June Boat-based survey The Narrows; Port Curtis 19 June Boat-based survey Port Curtis 5

17 2.3 Marine Megafauna Boat-based Observations Boat-based observations included boat-based megafauna survey and acoustic baseline survey techniques. Boat-based surveys collect observational data at fine spatial scales. This was supported by acoustic monitoring to provide baseline acoustic values of the sites observed to facilitate future data analysis. The boat-based survey was undertaken by two experienced marine megafauna ecologists onboard the live-aboard marine vessel RAB, assisted by the skipper and deckhand when necessary Transects and spot sampling sites A stratified boat-based survey across a variety of depths and habitats was designed, taking into consideration habitat information resulting from epi-benthic habitat mapping (GHD 2009a, Rasheed et al. 2008). Figure 2-2 shows the survey sites overlayed over seagrass habitat mapping by Rasheed et al Benthic habitat mapping reported by Rasheed et al. (2008), describes the Port Curtis habitat prior to major environmental change or dredging activity. Survey consisted of a combination of transects and spot sampling sites associated with the beginning/end of a transect in addition to dedicated spot sample sites (i.e. not associated with a transect), shown in Figure 2-1. Sites included transects and spot sample sites from previous surveys in Port Curtis and Port Alma (GHD 2009b), for comparison, in addition to numerous sites that were located near impacts such as rock dumping, pile driving and shipping vessel movements (>50 sites as per requirement). The sampling effort was deemed appropriate to capture the diversity of species in the area by the survey team within the available timeframe. This design covered the heterogeneous and patchy habitat in the port environment in the context of known marine fauna aerial survey and habitat data for this region. This approach provided for a theoretical increase in detectability within the survey area as known habitat areas were targeted. These methods have been used successfully in other areas by the survey personnel (e.g. Moreton Bay, Bowen, Townsville, Abbot Point and previously in Port Alma and Gladstone). This method has previously been endorsed for application by the Great Barrier Reef Marine Park Authority (GBRMPA) and input with technical comment from the Department of Environment and Resource Management (DERM) for similar development sites along the east coast of Queensland. 6

18 Boat-based Transects Boat-based transects were undertaken throughout the study site to determine distribution and relative abundance of marine megafauna. Scanning methods for transects were adapted from those outlined in Beasley et al. (2010), which refers to methods used for monitoring inshore dolphins in the western Gulf of Carpentaria (Marsh et al. 2010). Following the methodology described in Beasley et al. (2010), transect surveys were conducted at a consistent low speed (15 19 km/h, 8-10 knots). Surveys conducted at higher speeds have a reduced probability of observing megafauna, therefore survey speed was consistently maintained across all transect lines. Once megafauna were sighted, data was collected at the sighting location on: Time and date GPS location Species Number of individuals Age class of group (note that the age range of dolphins was not possible to discern) (Table 2-2) Identifiable behaviours Environmental parameters (Beaufort sea state, depth, temperature, turbidity and salinity). When possible, photographs of dolphins and turtles sighted were taken to assist in species identification. 7

19 7,415, , , ,000 ROCKHAMP TON - EMU PARK ROAD 265, , , , , , , , , , , , , , , , , , , , , , , ,000 7,415,000 7,385,000 7,390,000 7,395,000 7,400,000 7,405,000 7,410,000 BAJOOL - PORT ALMA ROAD See Inset Inset KANGAROO ISLAND THE NARROWS Friend Point Laird Point PORT C URTIS WAY GRAHAM CREEK CURTIS ISLAND PORT CURTIS BRUCE HIGHWAY TARGINIE ROAD PORT C URTIS WAY DAWSON HIGHWAY BOYNE ISLAND ROAD TANNUM SANDS ROAD ,340,000 7,340,000 7,385,000 7,390,000 7,395,000 7,400,000 7,405,000 7,410,000 7,380,000 GLADSTONE 7,380,000 7,365,000 7,370,000 7,375,000 7,365,000 7,370,000 7,375,000 7,360,000 7,360,000 7,355,000 7,355,000 7,350,000 7,345,000 7,350,000 7,345,000 7,335, , , , , , , , , , , , , , , , , , , , , , , , , , , ,000 7,335,000 Port of Gladstone Western Basin Dredging and Disposal Project 1:350,000 (at A3) LEGEND Job Number Gladstone Seagrass Meadows November 2008 Isolated patches/ Revision B Gladstone spot sites Continuous cover Aggregated patches Date 05 AUG 2011 Kilometres Gladstone transect lines Aggregated patches Isolated patches Boat-based survey sites overlayed Aggregated patches/ Deep water meadow Map Projection: Universal Transverse Mercator Continuous cover with seagrass habitat mapping by Horizontal Datum: Geocentric Datum of Australia Rasheed et al Figure 2-2 Grid: Map Grid of Australia 1994, Zone 56 Path: G:\41\23667\GIS\Maps\Working\41_23667_009_Seagrass_rev_b.mxd Level Charlotte Street Brisbane QLD 4000 Australia T F E bn @ghd.com W While GHD has taken care to ensure the accuracy of this product, GHD, DEEDI and GA make no representations or warranties about its accuracy, completeness or suitability for any particular purpose. GHD, DEEDI and GA cannot accept liability of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred as a result of the product being inaccurate, incomplete or unsuitable in any way and for any reason. Data source: GHD; Survey spot sites, transect lines, Zoning/2011, DEEDI:Seagrass/2008,GA; Ocean, Roads, Railway, Coastal Boundaries/2011 Created by: MS

20 Table 2-2 Indicative age class categories for green turtle, dugong and inshore dolphins Species Age class Size (curved carapace length for turtles) Age range (years) Green turtle (Chelonia mydas) Adult cm 32 + Subadult cm Juvenile cm 5 18 Dugong (Dugong dugon) Adult cm Calf 100 cm 240 cm (closely associated with adult) Indo-Pacific humpback dolphin (Sousa chinensis) Adult cm N/A Juvenile cm N/A Calf 100 cm 150 cm (closely associated with adult) N/A Inshore bottlenose dolphin (Tursiops spp.) Adult cm N/A Calf cm N/A Snubfin dolphin (Orcaella heinsohni) Adult cm N/A Juvenile cm N/A Calf <100 cm 150 cm (closely associated with adult) N/A Source: Adapted from - Chaloupka and Limpus, 2005, Marsh et al. 2004, Jefferson et al Dolphins are most regularly sighted in groups compared with other marine megafauna species. A dolphin group/cluster was defined following Shane (1990) and Ford (1989) as a tight aggregation with one or more dolphins in close proximity (0 500 m), in apparent association, moving in the same direction, and often, but not always, engaged in the same activity. Following Smith and Reeves (2000), group size was estimated based on low, high and best estimates of the number of animals. Group size was estimated after at least 10 minutes of careful observation of the group. Low was the absolute minimum number of dolphins sighted in the group, high was the absolute maximum number of dolphins in the group, and best was the best estimate of the number of dolphins, acknowledging low and high estimates. Behavioural data were systematically recorded where possible, with categories following those developed for inshore dolphins in northern Australia based on Parra (2006) and modified by Palmer (2010): 9

21 Foraging: Individuals moving in various directions without an obvious pattern. Dolphins diving frequently and steeply downwards (often preceded by fluke or peduncle arches), with extended submersion times. Rapid accelerations and erratic movement at the surface, indicative of animals chasing fish. Animals seen directly pursuing a fish (e.g. fish jumping at the surface) or with fish in their mouth. Foraging behind trawler: Repeated diving in varying directions around the side or behind the stern of a trawler boat while the boat is fishing. Slow travel - moving in slow and persistent directional pattern. Regular surfacing and diving pattern and animals are not underwater for great lengths of time. Fast travel - moving fast but in a persistent and directional pattern. Regular surfacing and diving patterns and animals are not underwater for great lengths of time. Socialising: Localised movement. Dive direction is unpredictable. Dolphins in close proximity showing high levels of interaction (animals touching each other, rubbing their bodies). Fins and flukes often break the surface of the water. Frequent aerial behaviour such as leaps and somersaults. Milling: Movement slow with no apparent direction. Dolphins swim in close proximity, but without interaction. No aerial behaviour, activity levels are low. Dolphins surface in a synchronised manner and most of the time is spent at the water s surface. Dive angles are shallow. Environmental parameters (Beaufort, depth, temperature, turbidity, salinity, tide state and phase (i.e. neap or spring)), were recorded at the start and end of every transect line, and at spot sampling sites. These data were used to investigate habitat utilisation and potential seasonality of sighting data and are available for application in the more extensive marine megafauna survey program (post-baseline study). Boat-based Spot Sampling Spot sampling is conducted in a single spot for ten minutes, to observe cryptic marine megafauna such as dugong and turtle, that may not be encountered during transect surveys. Dugongs spend less than 2% of their time at the surface of the water and often surface cryptically (Anderson 1981; Churchward 2001). A ten minute observation period for spot sampling was chosen because 90% of dugong dives are less than five minutes duration and dives greater than 10 minutes are very uncommon (Chilvers et al. 2004). Similarly, green turtles (Chelonia mydas) have recorded mean foraging dives of 4.5 mins (Rice et al. unpublished data). Cetaceans are also observed to surface regularly and have successfully been surveyed by undertaking boat-based transects (Lukoscheck and Chilvers 2008; Parra et al. 2006; Skrovan et al., 1999 and Stacey 1996). During the ten-minute spot sampling, two trained observers were positioned facing the bow and stern of the vessel with each observer scanning 180 o, this provides a combined search area of approximately km 2 (x 83 sites ). Once a species of marine megafauna was sighted, data was collected at the sighting location as described above for transects. Under good weather conditions (<12 knots; Beaufort 3), boat-based spot sample sites enable a sighting radius for surfacing marine megafauna (i.e. dugongs, turtles and dolphins) of approximately 200 m from the boat. Sighting distance is dependent upon sea state and weather conditions; as a result, an approximate distance of 200 m is given as the maximum distance of detection for dugongs, turtles and dolphins at any given survey time. This distance increases greatly with good weather conditions and declines with increased swell or wind affected sea surfaces. 10

22 Environmental Parameters Environmental parameter measurements were collected at each spot sample site, transect start and end point and for each marine fauna observation using a multi-probe water quality meter. The depth (m) to the ocean floor was also measured at these locations. The following parameters were collected at a depth of approximately 1.5 m below the surface of the water: Temperature Salinity Turbidity 2.4 Aerial Surveys Aerial surveys were conducted using methodology adapted from Marsh and Sinclair (1989a, 1989b) and Pollock et al. (2006). Surveys were conducted using a high-wing twin engine Partenavia 68B with survey markers attached to pseudo struts, which are fitted to the wings specifically for this purpose. During each survey event, one survey flight was performed at high tide and another at low tide, as per methodologies detailed in Groom (2003) and GHD (2009a, 2009b, 2010) to detect spatial changes in marine fauna with regards to tidal change. Two trained and experienced observers counted marine fauna within a strip of sea defined by marker rods attached to pseudo wing struts. The strip thus demarcated on either side of the aircraft is 200 m wide when the aircraft is flying at the nominal height (137 m). Observers seated on each side of the aircraft scanned the transects on their side, and observations were recorded. Surveys were conducted along pre-determined transect lines, as shown in Figure 2-3. Environmental observations During aerial surveys, observers recorded turbidity, glare and Beaufort sea state every two minutes. Turbidity was ranked on a scale of 1 to 4, with 4 being the most turbid. Glare was measured on a scale of 0-3, with 3 being the highest glare. Wind speed and sea state was ranked according to the Beaufort scale. 11

23 The Beaufort scale and turbidity scale categories are shown in Table 2-3 and Table 2-4 respectively. Table 2-3 Beaufort scale Force Description Sea state Speed (knots) 0 calm like a mirror <1 1 light air ripples, no foam light breeze small wavelets, smooth crests with glassy appearance gentle breeze large wavelets, some crests break, some white caps moderate small waves, frequent white caps breeze 5 fresh breeze moderate rather long waves, many caps, some spray strong breeze some large waves, extensive white foam crests, some spray Note: Acceptable conditions for conducting aerial surveys are shaded in grey Table 2-4 Turbidity scale Turbidity Water Quality Depth Range Visibility of Sea Floor 1 Clear Shallow Clearly visible 2 Variable Variable Visible but unclear 3 Clear > 5 m Not visible 4 Turbid Variable Not visible 12

24 280, , , , , , , , , ,400, ,400, ,360,000 MOUNT LARCOM! GLADSTONE 1128! ,360, ,350,000 TANNUM SANDS! CALLIOPE! ,320,000 7,320,000 7,370,000 7,370,000 7,380,000 7,380,000 7,390,000 7,390,000 7,410,000 7,410,000 C O R A L S E A INSET 7,350,000 7,340,000 Western Basin 2000 NORTH PASSAGE ISLAND 7,340, ,330,000 SOUTH PASSAGE ISLAND 7,330, ,310,000 Fisherman' s Landing Basin MIRIAM VALE! 7,310, , , ,000 LEGEND Transect Fisherman's Landing Northern Expansion Western Basin Reclamation Footprint Land Mass 310, , , , , ,000 1:500,000 (at A4) Kilometers Map Projection: Universal Transverse Mercator Horizontal Datum: Geocentric Datum of Australia 1994 Grid: Map Grid of Australia, Zone 56 o G:\42\15386\GIS\WesternBasinProjects\MXDs\WB_319_rev_a.mxd Level Charlotte Street Brisbane QLD 4000 Australia Port of Gladstone Western Basin Dredging and Disposal Project Marine Megafauna Survey Aerial Transects over the Survey Area Job Number Revision A Date 15 Sept 2009 Figure 2-3 T F E bn @ghd.com W This map contains data that is sourced from Data Custodians under Copyright. Please refer to EIS Appendices for Ownership and Copyright details This document is and shall remain the property of GHD. The document may only be used for the purpose for which it was produced. Unauthorised use of this document in any way is prohibited. While GHD has taken care to ensure the accuracy of this product, GHD Pty Ltd and Data Custodians make no representations or warranties about its accuracy, completeness or suitability for any particular purpose. GHD Pty Ltd and Data Custodians cannot accept liability of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred as a result of the product being inaccurate, incomplete or unsuitable in any way and for any reason.

25 2.5 Acoustic Monitoring Acoustic measurements were recorded at the same observation sample sites and transect points in the study area (Figure 2-1) during summer and autumn survey periods. Three categories of noise were considered during these measurements, as outlined below. Ambient noise Incorporated with other marine megafauna monitoring surveys, ambient underwater noise measurements were undertaken throughout the identified Study Area zones during different times of the day [1] to determine the baseline ambient underwater noise level and its variation. Different frequency weightings for different marine megafauna species were also applied to the noise measurements to estimate the acoustic energy that the various marine megafauna species are exposed to. Anthropogenic noise A number of anthropogenic noise sources, including pile driving, rock dumping and bulk carrier movements (including construction vessels), were reactively measured in the Study Area. The measurements of these anthropogenic noise sources were undertaken to estimate the received levels from these noise sources. Marine fauna vocalisation Marine fauna emit various noises including vocalising and echo-locating for prey capture and communication. This is generally not consistent across species whereby some species produce noise more frequently and are more easily identifiable. For example, snapping shrimp frequently saturate background acoustic readings in inshore tropical environments. They produce a highly audible sound from the cavitation produced from their snapping claws (Au and Banks 1998). Any marine fauna noise sources were captured opportunistically i.e. wherever there was a marine fauna sighting; hydrophones were deployed in addition to sources recorded at designated sample sites Measurement Setup Two hydrophones were deployed via cable and supported with buoys so they were positioned in the middle of the water column (determined by the depth sounder at the measurement location). When recording, the engine and the echo-sounder of the vessel were turned off in order to reduce vessel and flow noise at the hydrophone (see Figure 2-5). [1] The day has been separated into morning, daytime, evening and night time periods. Morning is defined as the period from dawn to 3 hours after sunrise; day is defined as 3 hours after sunrise to sunset; evening is defined as dusk (i.e. sunset to night time) and night time ends at dawn. The time periods have been selected to represent the periods when various marine fauna types vocalise or don t vocalise. Vocalisations will elevate the localised ambient noise levels which will be seen in the measured data. 14

26 Figure 2-4 Reson TC4032 hydrophones each with a 50 m cable attached Buoys supporting hydrophone 1 Buoys supporting hydrophone 2 Figure 2-5 Buoys supporting the deployment of the two hydrophones from the survey vessel 15

27 3. Survey Results 3.1 Overview All sightings from boat-based and aerial surveys have been combined in Figure 3-1 and colour coded (black = summer sightings; red = autumn sightings) to visually depict potential spatial variability between survey events and potential clusters or aggregations of taxa. Using species presence as a surrogate measure of habitat importance, the survey region is demonstrated to have conservation importance to marine megafauna species. With all observational survey data combined, varying densities of marine fauna become apparent within the survey zones. Marine fauna were not observed to occur within the immediate coastal construction sites adjacent (west) to Curtis Island however, they were observed to be present (in low numbers) near the recently developed bund wall and barge landing facility in Graham s Creek and south of the Passage Islands, as per surveys prior to development. The area north east of the Calliope River and south of Graham Creek is undergoing considerable change due to infrastructure development. Comparing the map outputs of boat-based and aerial surveys from 2009 to recent surveys, the area was found to have reduced presence of marine turtle, dugong and dolphin compared to earlier surveys undertaken for the WBDDP suggesting an indirect impact of habitat displacement has likely occurred. 16

28 7,415, , , ,000 ROCKHAMP TON - EMU PARK ROAD 265, , , , , , , , , , , , , , , , , , , , , , , ,000 7,415,000 7,400,000 7,400,000 7,390,000 7,385,000 BAJOOL - PORT ALMA ROA D 7,390,000 7,385,000 BRUCE HIGHWAY PORT CURTIS WAY TARGINIE ROAD DAWSON HIGHWAY BOYNE ISLAND ROAD TANNUM SANDS ROAD 7,340,000 7,335,000 7,340,000 7,345,000 7,350,000 7,345,000 7,350,000 7,355,000 7,355,000 7,360,000 7,360,000 7,365,000 7,365,000 7,370,000 7,370,000 7,375,000 7,375,000 7,380,000 7,380,000 7,395,000 7,395,000 7,405,000 7,405,000 7,410,000 7,410,000 KANGAROO ISLAND THE NARROWS Friend Point Laird Point GRAHAM CREEK CURTIS ISLAND See Inset 1 Inset 1 PORT CURTIS WAY PORT CURTIS 250, , , , , , , , , , , , , , , , , , , , , , , , , , ,000 7,335,000 1:350,000 (at A3) Kilometres Map Projection: Universal Transverse Mercator Horizontal Datum: Geocentric Datum of Australia Grid: Map Grid of Australia 1994, Zone 56 o LEGEND June Sightings 2011 March Sightings 2011 Main Roads Railway Urban Area Path: G:\41\23667\GIS\Maps\Working\41_23667_019_All_Survey Sites_Mar_June_rev_a.mxd While GHD has taken care to ensure the accuracy of this product, GHD and GA make no representations or warranties about its accuracy, completeness or suitability for any particular purpose. GHD and GA cannot accept liability of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred as a result of the product being inaccurate, incomplete or unsuitable in any way and for any reason. Data source: GHD: March Sightings, June Sightings/2011 GA; Ocean, Roads, Railway, Coastal Boundaries/2011 Created by: MS Port of Gladstone Western Basin Dredging and Disposal Project All boat-based and aerial observations of marine fauna during the project Job Number Revision Date A 1 Aug 2011 Figure 3-1 Level Charlotte Street Brisbane QLD 4000 Australia T F E bn @ghd.com W

29 3.2 Boat-based Surveys Weather Conditions Survey conditions were fine throughout most of the project period, with occasional rain on March 4 during survey 1. During survey 2, no rainfall occurred and wind speed ranged between 4 and 19 km/h. Of relevance to the acoustic sampling, swell heights differed between measurements but were estimated to be between 20 cm to 1 m throughout the survey area. Currents ranged from moderate to relatively strong during the sampling times and flow noise over the hydrophone was minimised by allowing the vessel to drift with the current. These moderate weather conditions did not impact the localised ambient noise level at the measurement points. They would, however, have influenced the distant background noise in the deeper ocean and along the coastline due to wave action and breaking waves. Weather conditions during survey are shown in Table 3-1. Weather conditions leading up to survey events are detailed in Appendix A. Table 3-1 Weather conditions on survey Date Temp ( o C) min/max Rain (mm) 9 am wind dir. 9 am wind speed km/h 3 pm wind dir. 3 pm wind speed km/h 27 February 22.1 / ESE 15 ENE February 22.8 / ENE 15 ENE 19 1 March 23.3 / ENE 11 ENE 13 2 March 24.8 / WSW 4 NE 15 3 March 24.7 / NNW 9 NE 13 4 March 23.2 / W 4 NE June 12.8 / WSW 7 NE June 10.8 / WSW 4 WSW June 10.5 / WSW 11 NE 7 16 June 10.4 / SW 11 SE 6 17 June 10.6 / WSW 9 WSW June 11.5 / WSW 6 SW June 10.8 / S 19 NE Marine Megafauna Sightings during Boat-based Surveys Dolphins and turtles were the most prevalent species observed during the surveys (Table 3-2, Appendix D). Although more dolphins were observed during the second survey event, fewer turtles were seen despite a general improvement in turbidity across the study area except for Port Alma where only two 18

30 turtles were observed during the survey period. A large number of juvenile/subadult green turtles were observed (Figure 3-2) highlighting the importance of this inshore region for young turtles. The Indo- Pacific humpback dolphin was the most frequently observed species on survey and a number of juvenile/sub adult individuals were identified, mainly on the first survey. An Indo-Pacific humpback dolphin calf was also observed during this survey. Snubfin dolphins were also observed with relative frequency in the Port Alma area only. A range of other taxa were also observed, including dugong, rays, seasnakes and different turtle and dolphin. In all cases across both surveys fewer than 10 individuals of any one of these groups were observed (Figure 3-2, Table 3-2). Snubfin dolphins were observed only at Port Alma and in the far northern region of Curtis Island while Indo-Pacific humpback dolphins were primarily observed around Port Curtis. Green turtles were noted to be present in the Narrows on both surveys (Figure 3-3). They were also observed to occupy Pelican Banks (where a significant seagrass meadow is located), South End of Curtis Island, habitats to the east of Facing Island and possibly Port Alma (un-identified turtle species observed here), despite the lack of seagrass meadows in that location. It may be that these sightings represent turtles using the area as a transient pathway between preferred feeding habitat to the south and north or they may have been supplementing their diets with mangrove leaves (occurring throughout the region) which has been recorded in Port Curtis (pers. comm. DERM, C. Limpus). 90 Observed Frequency Calf Juvenile/Sub-adult Adult Inshore Bottlenose Dolphin Indo-Pacific Humpback Dolphin Snubfin Dolphin Unidentified Dolphin species Dugong Seasnake Green Turtle Hawksbill Turtle Loggerhead Turtle Unidentified Turtle Species Figure 3-2 Age class frequency of marine megafauna observations 19

31 Table 3-2 Number of marine megafauna sightings during both boat-based surveys Species Survey 1 Survey 2 Total Dolphins 16 (n=53) 19 (n=71) 35 (n=124) Indo-Pacific humpback 12 (n=42) 13 (n=43) 25 (n=85) Australian snubfin 3 (n=8) 5 (n=26) 8 (n=34) Inshore bottlenose 0 1 (n=2) 1 (n=2) Un-identified dolphin species 1 (n=3) 0 2 (n=3) Dugong 2 (n=2) 1 (n=1) 3 (n=3) Turtles 39 (n=52) 15 (n=16) 54 (n=68) Green turtle 12 (n=24) 5 (n=5) 17 (n= 29) Hawksbill turtle 2 (n=2) 0 2 (n=2) Loggerhead turtle 3 (n=3) 1 (n=1) 4 (n=4) Unidentified turtle species 22 (n=23) 9 (n=10) 31 (n=33) Seasnakes 5 (n=5) 1 (n=1) 6 (n=6) Total 62 (n=112) 36 (n=89) 98 (n=201) Note: (n) = number of individuals A detailed understanding of the individual species observations variability between the two survey events is provided in the following sections. 20

32 ROAD 7,400,000 7,405,000 7,410,000 7,415, , ,000 SLEIPNER COOLCORRA NANKIN 270, , ,000 JOSKELEIGH ROSS RANGE FLAT TOP RANGE EUREKA FLAT 285,000 [ [ [ 290,000 [!O( 295, ,000 [ 305,000 [!O( 310, , , , ,000 [ 335, , ,000 [ FISHERMAN'S LANDING [!O( [ [ [ [ [ 350, , , ,000 SOUTHEND NORTHCLIFFE!O(!O(!O(!O( 370,000 7,400,000 7,405,000 7,410,000 7,415,000 7,385,000 7,390,000 7,395,000 BAJOOL C.Q. SALT SIDING BAJOOL - PORT ALMA ROAD [ PORT ALMA!O(!O( RAMSAY CROSSING!O(!O( RAMSAY RANGE Inset 1 PORT CURTIS WAY CALLEMONDAH [ SOUTH GLADSTONE [!O( GATCOMBE 7,385,000 7,390,000 7,395,000 7,365,000 7,370,000 7,375,000 7,380,000 REDAN RANGE MARMOR RAGLAN DARTS CREEK EPALA AMBROSE DEVERSOIR HUT CREEK RUNDLE RANGE BUTLERVILLE!O( [ [Z!O( [ [ [ [ [ [ [!O( [ MOUNT LARCOM RANGE FISHERMAN'S LANDING YARWUN INDUSTRIAL ESTATE See Inset 1!O(!O( SOUTHEND NORTHCLIFFE!O(!O( CURTIS CHANNEL 7,365,000 7,370,000 7,375,000 7,380,000 7,360,000 ULAM RANGE MACHINE CREEK YARWUN TARGINIE ROAD PORT CU RTIS WAY CALLEMONDAH [ [ SOUTH GLADSTONE!O( GATCOMBE 7,360,000 EAST END GLADSTONE - BENARABY 7,355,000 BRACEWELL BEECHER 7,355,000 7,350,000 CALLIOPE RANGE CEDAR VALE CALLIOPE CROSSING BRU CE HIGHWAY BURUA BOY NE ISLAND ROAD!O( 7,350,000 MOUNT ALMA RANGE WURDONG HEIGHTS RODDS PENINSULA 260, , , , , , , , , , , , , , , , , , , , , , ,000 1:300,000 (at A3) Kilometres Map Projection: Universal Transverse Mercator Horizontal Datum: Geocentric Datum of Australia Grid: Map Grid of Australia 1994, Zone 56 o LEGEND 6Z Group Size Z 0-1 Z Z Path: G:\41\23667\GIS\Maps\Working\41_23667_011_Boat_Based_Marine_sightings_June_2011_rev_a.mxd While GHD has taken care to ensure the accuracy of this product, GHD and GA make no representations or warranties about its accuracy, completeness or suitability for any particular purpose. GHD and GA cannot accept liability of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred as a result of the product being inaccurate, incomplete or unsuitable in any way and for any reason. Data source: GHD; All June Sightings - Boat Based/2011 GA; Place Name, Ocean, Roads, Railway, Coastal Boundaries/2011 Created by: MS Z Sightings [ Dolphin - Bottlenose [ Dolphin - Humpback [ Dolphin - Snubfin [ Dugong [Z Seasnake!O( Turtle Urban Area Railway Main Roads Port of Gladstone Western Basin Dredging and Disposal Project All boat-based sightings June, 2011 Job Number Revision Date A 14 July 2011 Figure 3-3 Level Charlotte Street Brisbane QLD 4000 Australia T F E bn @ghd.com W

33 3.2.3 Dolphins A total of 35 groups of dolphins (124 individuals) were observed during both surveys and across all five zones. Dolphin observations were comparable between survey 1 (summer) and survey 2 (autumn), with slightly more observations and total counts recorded in survey 2 for all species. Bottlenose dolphins were only observed during survey 2 at the northern end of Curtis Island. Dolphins were observed to exhibit numerous behaviours including socialising, milling and feeding. Figure 3-4 below shows an Indo-Pacific humpback adult dolphin jumping within Port Curtis. Figure 3-5 shows an Indo-Pacific humpback dolphin observed to be playing with a strap of algae. Similar behaviours from this species have previously been observed in the Hinchinbrook and Darwin harbour regions. Figure 3-4 Indo-Pacific humpback dolphin jumping in Port Curtis Figure 3-5 Indo-Pacific humpback dolphin playing with a strap of algae 22

34 Indo-Pacific Humpback Dolphins Twenty-five groups of Indo-Pacific humpback dolphins were observed (n= 85 individuals) during boatbased surveys. The number of observations and total individuals sighted were relatively comparable between events; survey 2 recorded more Indo-Pacific humpback dolphins (13 groups, 43 individuals) than survey 1 (12 groups, 42 individuals). The average group size was 3.4 individuals (+ s.e ), with a range of 1 to 9 individuals. 70.6% of Indo-Pacific humpback dolphins observed were adults, 24.7% were juveniles and 1.2% were calves. The majority of Indo-Pacific humpback dolphins were observed in the Port Curtis region (n=51). Observations of Indo-Pacific humpback dolphins varied between the two survey events, as shown in Figure 3-6. During survey 2 (June), Indo-Pacific humpback dolphins were observed at each location; however observations were not recorded in Rodds Bay or Eastern Curtis Island during survey 1 (February/March). More Indo-Pacific humpback dolphins were observed at Port Alma and Port Curtis during survey 1 than survey 2. Sightings of Indo-Pacific humpback dolphins in Port Curtis were consistently the highest of all survey areas Survey 1 Survey 2 Observed Frequency Port Alma Narrows Eastern Curtis/Facing Island Port Curtis Rodd's Bay Figure 3-6 Indo-Pacific humpback dolphins observed during boat-based survey Snubfin Dolphins A total of eight groups of snubfin dolphins (n=34 individuals) were observed during both survey events with all observations occurring in, or in close proximity to Port Alma. Again, more dolphins were recorded in survey 2 (5 groups, 26 individuals) than survey 1 (3 groups, 8 individuals). A large proportion of the individuals observed were adults (91%), with only 1 juvenile and 2 calves observed (Figure 3-8). 23

35 Average group size was 4.25 (s.e. 0.60), with a range of 1 to 15 individuals per group. Observations occurred within waters of relatively high turbidity, which is characteristic of the Port Alma aquatic environment. Figure 3-7 shows a group of snubfin dolphins socialising in the Port Alma area. Figure 3-7 A group of snubfin dolphins observed in Port Alma Observed Frequency Calf Juvenile/Sub-adult Adult 0 E. Curtis/ Facing Island E. Curtis/ Facing Island Port Alma Port Alma Survey 1 Survey 2 Survey 1 Survey 2 Figure 3-8 Group size and age class for snubfin dolphins observed during both survey events 24

36 Inshore Bottlenose Dolphins Two inshore bottlenose dolphins were observed on one occasion north of Curtis Island (for details see Appendix C). Both individuals, identified as adults, were observed to be travelling slowly adjacent to the coast line. They were identified as inshore bottlenose dolphin species due to their small size, relatively long rostrum and small group size. Figure 3-9 Inshore bottlenose dolphin observed north of Curtis Island Dugong Sightings During survey 1, two adult dugongs were sighted near Pelican Banks (Port Curtis, near Southern Curtis Island). Pelican Banks is reported to contain some of the last remaining seagrass habitat in the area (pers. comm H. Taylor, DEEDI, 2011) following the extensive wet season. One adult dugong was sighted during survey 2, also at Port Curtis near Pelican Banks. Details of the dugong sightings can be found in Appendix D Turtle Sightings A total of 68 turtles were observed during both survey events. A greater number of turtles were observed during survey 1 (n=52) than survey 2 (n=16). The aggregations comprised of 29 green turtles (Chelonia mydas), two hawksbill turtles (Eretmochelys imbricata), four loggerhead turtles (Caretta caretta) and 33 un-identified turtle species (species remained unidentified due to brief periods of observation). The difference between recorded turtle observations may be attributed to the cooler air and surface temperatures during winter, whereby increased exposure at the surface of the water would provide potential for heat loss rather than an opportunity for warmth as more likely in summer periods when basking is common. The habitat associated with the eastern side of Curtis and Facing Islands is rocky reef and numerous turtle sightings during survey 1 were from this area. This diversity of habitat may have supplemented diets of numerous animals that may have usually been more dependent upon seagrass habitats. 25

37 Green Turtles Twenty-nine green turtles were recorded overall. Green turtles were observed in all study zones except possibly Port Alma, two turtles were observed in Port Alma but their species identity was not determined due to distance. Most observations occurred at eastern Curtis Island during survey 1, where 20 green turtles were recorded (Figure 3-10). There was substantially more sightings than during survey 2. This may have been to access alternative food resources on rocky reef habitat however this cannot be determined conclusively and doesn t explain why more animals were not observed on the second survey. All other locations and events recorded sightings of less than five individuals. 83% of turtles observed were juveniles/ sub-adults, and the remaining 17% were adults. The location of green turtles and the group composition is shown in Figure 3-10 which demonstrates the predominance of the juvenile age class across sites. One juvenile/sub-adult green turtle was recovered from the Port Curtis zone during survey 1; it was emaciated and unable to dive. The turtle was given to the Department of Environment and Resource Management (DERM) in Gladstone Juvenile/Sub-adult Adult Narrows Narrows Eastern Curtis/Facing Island Observed Frequency Eastern Curtis/Facing Island Port Curtis Port Curtis Rodds Bay Rodds Bay Survey 1 Survey 2 Survey 1 Survey 2 Survey 1 Survey 2 Survey 1 Survey 2 Figure 3-10 Age class and location of green turtles observed during both survey events Hawksbill Turtles Hawksbill turtles were only observed during survey 1. Two individuals (one adult and one juvenile/subadult) were sighted on the seaward side of Facing Island, in association with a number of other turtles and a rocky reef environment (Appendix C). 26

38 Loggerhead Turtles A total of four loggerhead turtles were observed during both survey events. The majority of sightings occurred during survey 1 and of the three adult turtles observed, one was in Rodds Bay and two were on the seaward side of Facing Island (Appendix C). The loggerhead turtle observed during survey 2 was sighted in Port Curtis in a deep-water channel over soft benthic habitat as detected by the vessel sounder. Unidentified Turtle Species A total of 33 turtles were sighted that could not be identified from boat-based observations due to the brevity of observation (Figure 3-11). The majority of these were recorded in survey 1 (n=23). A large proportion (76%) of all turtles observed were adults (Appendix C) Survey 1 Survey 2 12 Observed Frequency Port Alma Narrows Eastern Curtis/Facing Island Port Curtis Rodds Bay Figure 3-11 Location and frequency of turtle observations (unidentified species) Seasnakes A total of six seasnakes were observed during both surveys; five during survey 1 and one during survey 2. Seasnakes were not observed in groups. The majority of seasnake sightings occurred in the Narrows (three sightings during survey 1 and one sighting during event 2, and sightings also occurred at Eastern Curtis/Facing Island and Port Alma (Appendix C). No environmental parameters were measured at the sighting locations Comparison with Existing Datasets Previous boat-based surveys in the Port Curtis region undertaken by GHD in 2009 show the same species utilising the region as those recorded from the current surveys, however there has been a 27

39 decline in presence and a shift in distribution. A comparable amount of survey time (to previous surveys) was spent in Port Curtis and the Narrows during this survey; however, observations of marine fauna in the Port Curtis region appear to have declined, with the exception of dugong which had infrequent sighting data in 2009 (Figure 3-12). Frequency of observed species Turtle Indo-Pacific humpback dolphin Dugong 5 0 Apr-09 May-09 Jul-09 Feb/Mar-11 Jun-11 Survey Date Figure 3-12 Comparison of survey observations between years in Port Curtis 28

40 3.3 Aerial surveys Weather Conditions during Aerial Surveys Meteorological conditions can affect the veracity of data collected during aerial surveys given that observation ability is reliant on good visibility of marine megafauna either at the sea surface or just beneath it. As such, haze, cloud cover, glare and other factors can influence the ability to sight fauna. Surveys are timed to achieve good weather; however this can be variable on the day. Understanding weather conditions on the days of survey is, therefore, important for interpreting observations. Conditions on the aerial survey days were variable. Wind speed (which influences wave height and ocean surface) was generally low except for waters offshore of Curtis Island, where comparatively stronger winds were experienced during both events. Cloud cover was low but remained at a height above the survey altitude (approximately ft.) during survey 1. Cloud cover was not present in the morning of survey 2, and was high during the afternoon survey. Visibility remained between 20,000 and 25,000 m. Flight details and conditions recorded on each survey are outlined in Appendix E. Turbidity glare and Beaufort sea state were recorded regularly during transect surveys, as per the methodology described in Section 2.4. Although variable between the survey sites, the water clarity was on average, quite turbid, which is typical for this area of the Queensland coastline. Higher turbidity was more prominent at Port Alma and less at Eastern Curtis Island. Beaufort state and glare conditions were however, relatively good for the survey events (Appendix E). These conditions have been considered for interpreting observational data from aerial surveys. Table 3-3 Average values for turbidity, glare and Beaufort sea state for both survey events Turbidity Glare Beaufort Survey Survey Marine Megafauna Sightings during Aerial Surveys Markedly more animals were observed during survey 2 than survey 1 (n=143 vs. n=37, Table 3-4). On survey 2 most sightings occurred in the afternoon (low tide) aerial survey. Across both surveys, dolphins (principally Indo-Pacific humpback) and turtles dominated the taxa observed, however during survey 2, rays were also commonly seen (Table 3-4). These were observed occupying the offshore waters north east of Curtis Island as well as habitats to the south in Rodds Bay (Figure 3-17). Dolphins were observed across all of the study area except the Narrows, east of Curtis Island and the WBDDP footprint (Figure 3-16 and Figure 3-17). Turtles were seen to be using the Narrows and Eastern Curtis Island and were observed throughout the southern areas of the study footprint but were uncommon in the WBDDP footprint and at Port Alma (Figure 3-16 and Figure 3-17). 29

41 Table 3-4 Summary of marine megafauna observations during summer and autumn aerial surveys 2011 Survey 1 Survey 2 Species AM PM AM PM Total (high tide) (low tide) (high tide) (low tide) Dolphin 5 (n=7) 1 (n=3) 4 (n=6) 19 (n=41) 29 (n=57) Inshore bottlenose 1 (n=3) (n=6) 3 (n=9) Indo-Pacific humpback 3 (n=3) 1 (n=3) 2 (n=4) 8 (n=19) 14 (n=29) Australian snubfin 1 (n=1) 0 1 (n=1) 1 (n=4) 3 (n=6) Unidentified sp (n=1) 8 (n=12) 9 (n=13) Dugong 0 1 (n=1) 3 (n=3) 6 (n=7) 10 (n=11) Ray 0 1 (n=1) 4 (n=12) 6 (n=14) 11 (n=27) Turtle 11 (n=17) 6 (n=6) 7 (n=7) 37 (n=49) 61 (n=79) Seasnake 1 (n=1) 0 1 (n=1) 0 2 (n=2) Shark 1 (n=1) 0 1 (n=1) 2 (n=2) 4 (n=4) Total 18 (n=26) 9 (n=11) 20 (n=30) 70 (n=113) 117 (n=180) Dolphins Three species across 29 dolphin groups with a total number of 57 dolphins were observed during aerial surveys. Markedly more dolphins were observed during the afternoon of survey 2 than at any other time. Weather conditions for the morning and afternoon survey were comparable; the afternoon survey was, however, conducted at low tide. Details of observations for all dolphins are provided in Appendix G. Indo-Pacific Humpback Dolphins Locations of Indo-Pacific humpback dolphin sightings varied; the greatest number of individuals observed was at Port Curtis (n=8) within similar numbers recorded at Port Alma and Rodds Bay (Figure 3-13). Fourteen groups of Indo-Pacific dolphins were observed during surveys; more groups were sighted during survey 2 (10 groups, 23 individuals) than survey 1 (4 groups, 6 individuals). 30

42 9 8 Survey 1 Survey 2 Observed Frequency Port Alma The Narrows Eastern Curtis/ Facing Island Port Curtis Rodd's Bay Figure 3-13 Observed frequency of Indo-Pacific humpback dolphins Snubfin Dolphins Three snubfin dolphin sightings (6 individuals) occurred during aerial surveys. Although only one snubfin dolphin was sighted in Port Alma during survey 1 (during high tide) a group of four snubfin dolphins were sighted during low tide in Port Alma during survey 2. In addition, an individual snubfin dolphin was observed off-transect at high tide in the Port Alma region during survey 2. No observations of snubfin dolphins south of Port Alma were made, which is consistent with information presented by Cagnazzi (2011) that Port Alma represents the southernmost extent for this species. Inshore Bottlenose Dolphins Survey 1 recorded one sighting of inshore bottlenose dolphins (with 3 individuals) during low tide at Port Curtis. Two sightings of bottlenose dolphins occurred during survey 2 in Rodds Bay (n=6 individuals) during low tide. One individual within the group was identified as a calf Dugongs Eleven dugongs were sighted during aerial survey 2, mostly during low tide. Sightings were all located within the southern half of the study area (Port Curtis near Facing Island, Eastern Curtis/Facing Island region and Rodds Bay (Figure 3-14 and Figure 3-16). No large aggregations were observed, with most sightings being of solitary individuals. Further details of each observation can be found in Appendix F. 31

43 Observed Frequency Survey 1 Survey Rodd's Bay Port Curtis Eastern Curtis/Facing Islands Figure 3-14 Observed frequency of dugong Turtles Of the 79 turtles observed during aerial surveys, 56 were seen during survey 2. Turbidity measured during the survey (vs. estimated during aerial observations) was generally lower at most sites during survey 2 (see Section 3.4). This may have contributed to better water clarity and a greater number of observations of turtles during the latter survey. The species of individual turtles observed during aerial surveys could not be discerned due to the height of the aircraft. During survey 1, the most sightings occurred in Port Curtis (n=15). During survey 2, 19 turtles were observed in Port Curtis, but the majority of turtles observed during survey 2 were reported from Rodds Bay (n=23). Of all turtle sightings, 44% were observed at low tide (Figure 3-15, Figure 3-16 and Figure 3-17). 32

44 25 20 Low tide High tide Observed frequency The Narrows The Narrows Eastern Curtis/ Facing Island Eastern Curtis/ Facing Island Port Curtis Port Curtis Rodd's Bay Rodd's Bay Survey 1 Survey 2 Survey 1 Survey 2 Survey 1 Survey 2 Survey 1 Survey 2 Figure 3-15 Location and tidal state for all turtle observations during aerial surveys Rays, Seasnakes and Sharks Rays, seasnakes and sharks were observed during both aerial survey events and are shown in Figure 3-16 and Appendix F. 33

45 7,340,000 7,360,000 7,380,000 7,400,000 7,420, ,000 JOSKELEIGH ROSS RANGE EUREKA FLAT [ BAJOOL - PORT ALMA ROAD!O( [!O( [ [ [!O( PORT ALMA [ DARTS CREEK RAGLAN EPALA AMBROSE DEVERSOIR HUT CREEK MACHINE CREEK EAST END BRACEWELL CEDAR VALE MOUNT ALMA RANGE DAWSON HIGHWAY CLARKE 300, , ,000 SOUTHEND NORTHCLIFFE!O( RUNDLE RANGE BUTLERVILLE MOUNT ALMA CROSSING RAMSAY RANGE RAMSAY CROSSING!O( [!O( MOUNT LARCOM RANGE!É(!É(! É( [ Inset 1!O( See Inset 1 FISHERMAN'S LANDING YARWUN INDUSTRIAL ESTATE YARWUN SOUTH GLADSTONE TARGINIE ROAD CALLIOPE CROSSING GLADSTONE MONTO ROAD CALLEMONDAH BEECHER BURUA!O( [ FISHERMAN'S LANDING YARWUN INDUSTRIAL ESTATE [!O( [ [!O( [Z [Z SOUTHEND NORTHCLIFFE GATCOMBE BOYNE ISLAND PORT CURTIS WAY [ ROAD WURDONG HEIGHTS GRAHAM BENARABY ALKINA RODDS BAY BOYNE RANGE TARAGOOLA [!O( [!O([ [Z [Z SOUTH GLADSTONE CALLEMONDAH!O(!O(!O( [!O(!O( [ IVERAGH!O(!O( 7,340,000 7,360,000 7,380,000 7,400,000 7,420,000 7,340,000 7,360,000 7,380,000 7,400,000 7,420,000 JOSKELEIGH ROSS RANGE 280,000 EUREKA FLAT [ [ [ [ [ RAGLAN PORT ALMA EPALA [ [ SEE AMBROSE INSET!O(!O(!O( [!É(!É(!O(!O(!O(!O( BURUA CALLIOPE CROSSING GRAHAM!O(!O(!O( [ [ [ [ DEVERSOIR MOUNT LARCOM RANGE HUT CREEK FISHERMAN'S LANDING YARWUN INDUSTRIAL ESTATE MACHINE CREEK YARWUN [!O(!O(!O( SOUTH GLADSTONE CALLEMONDAH BRACEWELL CEDAR VALE CLARKE DARTS CREEK EAST END MOUNT ALMA RANGE DAWSON HIGHWAY 300,000 RUNDLE RANGE BUTLERVILLE MOUNT ALMA CROSSING RAMSAY RANGE RAMSAY CROSSING TARGINIE ROAD GLADSTONE MONTO ROAD 320,000 See Inset 1 PORT CURTIS WAY BEECHER BOYNE RANGE TARAGOOLA BARMUNDU Inset 1 SOUTHEND NORTHCLIFFE [!O( [!O(!O( BOYNE ISLAND BENARABY ALKINA ROAD!O( GATCOMBE WURDONG HEIGHTS 340,000 P ORT CURTIS WAY CALLEMONDAH [ RODDS BAY [!O([ [!O( [ [ [ [!O(!O(!O( [!O(!É(!O(!O(!O(!É(!É( [!O(!O(!O(!É ([!O( [ [ [!É(!O(!O(!O(!O(!O(!O(!O(!O(!O( IVERAGH!O(!O( [ [ [ [ [!O( SOUTH GLADSTONE 360,000 SOUTHEND NORTHCLIFFE!O(!O( [ [!O(!O( GATCOMBE BRAY HILLS RODDS PENINSULA TURKEY BEACH TURKEY 7,420,000 7,400,000 7,380,000 7,360,000 7,340,000 BARMUNDU BRUCE HIGHWAY 7,320,000 BOROREN 7,320,000 7,320,000 High Tide BOROREN 7,320,000 Low Tide CALLIOPE RANGE THE TABLELAND MILTON RANGE WIETALABA MANY PEAKS RANGE BRUCE HIGH WAY WESTWOOD RANGE 280, , , , , , , , ,000 1:450,000 (at A3) Kilometres Map Projection: Universal Transverse Mercator Horizontal Datum: Geocentric Datum of Australia Grid: Map Grid of Australia 1994, Zone 56 o LEGEND Group Size Sightings [ Dolphin!O( Turtle [ Dugong [ Shark!É( Stingray [Z Seasnake Urban Area Main Roads Railway Port of Gladstone Western Basin Dredging and Disposal Project Job Number Revision Date A 22 July 2011 All aerial survey observations for high and low tide periods for surveys 1 (Feb/Mar) and 2 (June) combined Figure 3-16 G:\41\23667\GIS\Maps\Working\41_23667_020_All_sightings_High_Low_Tide_Mar_June_all_rev_a.mxd Level Charlotte Street Brisbane QLD 4000 Australia T F E bn @ghd.com W While GHD has taken care to ensure the accuracy of this product, GHD and GA make no representations or warranties about its accuracy, completeness or suitability for any particular purpose. GHD and GA cannot accept liability of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred as a result of the product being inaccurate, incomplete or unsuitable in any way and for any reason. Data source: GHD; All March and June Sightings/2011 GA; Place Name, Ocean, Roads, Railway, Coastal Boundaries/2011 Created by: MS

46 7,420, , , , , ,000 7,420, , , , , ,000 SOUTHEND NORTHCLIFFE SOUTHEND!O( [ NORTHCLIFFE 7,400,000 EUREKA FLAT!O( [ [ [!O( RAMSAY RANGE [ FISHERMAN'S LANDING YARWUN INDUSTRIAL ESTATE PORT CURTIS WAY SOUTH GLADSTONE CALLEMONDAH Inset 1 [Z 7,400,000 7,400,000 EUREKA FLAT [ [ [ [ [ [ [ [ [!O( [ [!É(!É( RAMSAY RANGE!É(!É(! É(!O( POR T CURTIS WAY Inset 1 [!O( [ [ [ [!O([ SOUTH GLADSTONE CALLEMONDAH [Z!O(!O(!O(!O( [ [!O( 7,400,000 PORT ALMA PORT ALMA 7,380,000 RAGLAN RUNDLE RANGE DARTS CREEK RAMSAY CROSSING [!O( See Inset 1 7,380,000 7,380,000 RAGLAN!O(!O(!O(!O( RUNDLE RANGE DARTS CREEK RAMSAY CROSSING!O(!O(!O(!O( See Inset 1!O(!O( 7,380,000 7,360,000 7,340,000 EPALA AMBROSE DEVERSOIR HUT CREEK MACHINE CREEK EAST END BRACEWELL CEDAR VALE MOUNT ALMA RANGE DAWSON HIGHWAY CLARKE MOUNT ALMA CROSSING SOUTHEND BUTLERVILLE NORTHCLIFFE MOUNT LARCOM RANGE [ FISHERMAN'S LANDING YARWUN INDUSTRIAL ESTATE YARWUN [Z SOUTH GLADSTONE TARGINIE ROAD PORT CURTIS WAY CALLIOPE CROSSING GLADSTONE MONTO ROAD CALLEMONDAH BEECHER BURUA GATCOMBE BOYNE ISLAND [ ROAD WURDONG HEIGHTS GRAHAM BENARABY ALKINA RODDS BAY BOYNE RANGE TARAGOOLA!O(!O(!O(!O(!O(!O(!O([!O(!O(!O(!O( [!É(!O( BRAY HILLS 7,340,000 7,360,000 7,340,000 7,360,000 EPALA DEVERSOIR SEE INSET AMBROSE HUT CREEK BRACEWELL CEDAR VALE MOUNT ALMA RANGE DAWSON HIGHWAY CLARKE MACHINE CREEK EAST END BUTLERVILLE MOUNT ALMA CROSSING!O( MOUNT LARCOM RANGE FISHERMAN'S LANDING YARWUN INDUSTRIAL ESTATE YARWUN TARGINIE ROAD!O( SOUTH GLADSTONE BEECHER GRAHAM BURUA CALLIOPE CROSSING GLADSTONE MONTO ROAD TARAGOOLA SOUTHEND!O( [ [ [ [!O( [ [ CALLEMONDAH BOYNE RANGE NORTHCLIFFE!O([!O(!O(!O( [Z [!O( [!O(!O( BOYNE ISLAND ROAD WURDONG HEIGHTS BENARABY ALKINA GATCOMBE [ [ [ RODDS BAY [ [!O([ [!O( [ [!O(!O(!O(!O(!O(!É(!O(!O(!O(!É(!É( [!O( [!O(!O(!O(!É( [ [ [!O(!O(!O(!O(!O(!O(!O( 7,360,000 7,340,000 BARMUNDU IVERAGH BRUCE HIGHWAY BARMUNDU IVERAGH BRUCE HIGHWAY 7,320,000 Feb/March BOROREN 7,320,000 7,320,000 June BOROREN 7,320, , , , , , , , , , ,000 1:450,000 (at A3) Kilometres Map Projection: Universal Transverse Mercator Horizontal Datum: Geocentric Datum of Australia Grid: Map Grid of Australia 1994, Zone 56 o LEGEND Group Size Sightings!O( Turtle [ Shark!É( Stingray [Z [ Dugong [ Seasnake Dolphin Urban Area Main Roads Railway Port of Gladstone Western Basin Dredging and Disposal Project All aerial survey observations for surveys 1 (Feb/Mar) and 2 (June) Job Number Revision Date A 22 July 2011 Figure 3-17 G:\41\23667\GIS\Maps\Working\41_23667_022_All_sightings_FebMar_June_all_rev_a.mxd Level Charlotte Street Brisbane QLD 4000 Australia T F E bn @ghd.com W While GHD has taken care to ensure the accuracy of this product, GHD and GA make no representations or warranties about its accuracy, completeness or suitability for any particular purpose. GHD and GA cannot accept liability of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred as a result of the product being inaccurate, incomplete or unsuitable in any way and for any reason. Data source: GHD; All March and June Sightings, Survey Path/2011 GA; Place Name, Ocean, Roads, Railway, Coastal Boundaries/2011 Created by: MS

47 3.4 Study Area Environmental Parameters Environmental parameters (depth, temperature, salinity and turbidity) were collected at the location of all waypoints to investigate: Environmental characteristics of the study area; and Abiotic characteristics of the habitat being used by marine megafauna The average value of these measurements reflects some variation between locations, which were grouped according to locality Port Alma, the Narrows, Eastern Curtis/Facing Island, Port Curtis and Rodds Bay. An overview of each environmental parameter is discussed below, and comparisons between survey 1 and survey 2 are discussed Depth Depth was measured at each transect and spot sample site by the vessel s depth sounder. Depth remained relatively similar between survey 1 and 2, indicating that survey sites were consistent and are therefore comparable. On average, Rodds Bay was the shallowest environment, and Port Curtis the deepest. Average depth and ranges are shown in Figure 3-18 (details are provided in Appendix G) Survey 1 Survey 2 7 Average Depth (m) Port Alma The Narrows East Curtis/Facing Island Port Curtis Rodd's Bay Figure 3-18 Average depth recorded during surveys - Error bars represent standard error (s.e.) Temperature Water temperatures in survey 1 (summer) were approximately 10 degrees warmer across all sites than that recorded in survey 2 (autumn) (Figure 3-19). This was consistent across all sites. 36

48 35 30 Survey 1 Survey 2 25 Temperature (oc) Port Alma The Narrows East Curtis/ Facing Island Port Curtis Rodd's Bay Figure 3-19 Average temperature recorded at survey localities - Error bars represent standard error (s.e.) Turbidity Across all sites, except Port Alma, turbidity was lower during survey 2, this is likely explained by the freshwater lens that would have been present during survey 1 at Port Alma (at < 2 m from the surface) following the wet season floods (Figure 3-20). Port Alma recorded the highest average and highest maximum turbidity levels during both surveys; this is likely due to the influence of the Fitzroy River at this site which maintains year-round high sediment loads that are discharged into the delta. Sites at eastern Curtis Island/Facing Island recorded the lowest average turbidity which is expected for an area with less coastal and estuarine influence than the inshore environments. Average turbidity values and range of values recorded during each survey are detailed in Figure During aerial surveys, turbidity was ranked from 0 to 4 using the scale described in Section 2.4. Turbidity values for each site during survey events are shown in Appendix G. 37

49 Survey 1 Survey 2 80 Turbidity (NTU) Port Alma The Narrows East Curtis/ Facing Island Port Curtis Rodd's Bay Figure 3-20 Average turbidity at survey localities - Error bars represent Standard Error (s.e.) Salinity There appeared to be a minor temporal trend in salinity, with survey 2 recording greater values than survey 1 at most sites (Figure 3-21). This is most likely associated with less rainfall during the survey 2 (autumn) period. This trend was consistent across sites, to varying degrees, and is most obvious at Port Alma and Port Curtis. These values are tabled in Appendix G. 38

50 45 40 Survey 1 Survey Salinity (ppt) Port Alma The Narrows East Curtis/ Facing Island Port Curtis Rodd's Bay Figure 3-21 Average salinity values recorded during survey events 3.5 Marine Acoustic Results and Analysis Ambient Background Noise A high-pass filter was applied to remove the flow noise component from the measurement data as the first 30 Hz of the measured data was dominated by flow noise from the survey vessel and the hydrophone. Where possible, the measurements used in the analysis were free of any anthropogenic noise, unless it had continual presence in the area so not to skew or misrepresent the actual ambient noise dataset. In areas such as Port Curtis, however, the significant amount of consistent anthropogenic noise has become part of the background noise field. Appendix I shows the results of the ambient noise measurements. Port Curtis, eastern Curtis and Port Alma survey areas have measurements of all four time periods, while Rodds Bay and The Narrows only have two captured periods. Assessment of the data collected (see Appendix I) demonstrates that background noise levels vary substantially between different times of the day, and also between study areas (Table 3-5). For most time periods, for each area, there were several measurements taken. The standard deviation (SD in Table 3-5 is from the average of the overall levels of these measurements, not the SD over a single measurement, thus making regions within the entire study area spatially comparable. Field observations noted several types of vessels within the study area; these were most frequently observed in Port Curtis. Vessels ranged greatly in their physical size, from recreational fishing boats and 39

51 jet skis to tugs and bulk carriers. The vessels were engaged in a range of activities including mooring with running gear on, in transit at low (< 6 knots), medium and high (>20 knots) speed, loading commodities and providing support to other vessels Marine Fauna Vocalisation Among the biological noise sources, snapping shrimp had a significant contribution to the ambient noise levels that were measured, particularly in the north-east area of Curtis, Port Curtis and The Narrows, during the morning and evening periods. The most significant fauna vocalisation recordings made during the June survey was that of the snubfin dolphin. Several recordings were made of vocalisations of individuals, pairs and groups of snubfin, at distances of 15 m to several hundred metres. All of the acoustic recordings were captured during the daytime and in the Port Alma region. Figure 3-22 shows the spectrogram of a recording of the bio-sonar of a snubfin passing at ~15 m from the measurement site. Most of the energy lies in the range of 10 khz khz, with some louder pulses extending past the limits of the data acquisition device (DAQ) which, at the sampling rate used, was 96 khz. Figure 3-23 shows the clearest recording of a socialising whistle captured. These whistles lie in the range of 4 khz 6 khz and last for around ms. 40

52 Figure 3-22 Bio-sonar of snubfin dolphin ~15 m from hydrophone Figure 3-23 Brief whistle of a snubfin dolphin circled in yellow 41

53 Port Curtis Based on field observations, the most important change to note in Port Curtis is the increase in the presence of boat traffic compared to the March survey. Commercial, personnel and equipment ferries, tug boats and tinnies dominated the noise field during the day and as a result the overall background noise levels during the day were higher by 13 db re 1 µpa when compared to survey 1. The day and evening noise average shows a 6 db increase in the standard deviation which reflects the varying nature of the port activities. Additionally, there has been an observed increase in noise levels which are within the hearing range of turtles, especially during the evening (Table 3-5). It is important to note that due to the large area designated as Port Curtis for this survey and the varying usage within this area, there was considerable variation in acoustic range across that area. This variation is not, however, apparent in the overall levels presented in the tables. By way of example, measurements taken near the coal terminal with a passing ferry reached levels of up to 140 db, whereas levels near the southern end of the Port Curtis survey area taper off to 104 db. This variation should be taken into account when viewing averages for an individual area. Eastern Curtis The background levels in eastern Curtis were generally consistent throughout the time periods of the day, however; there has been a 14 db increase during the day, when compared to the March survey in overall SPL levels as well for each of the cetacean types (Table 3-5). Similar to Port Curtis, there is a 12 db increase within the turtle hearing range across the whole day. The measurements taken in the morning were the lowest recorded for the whole survey at 104 db re 1 µpa. Similar to Port Curtis, there was a relatively large range in the received levels ( db) over the designated area. The variance noted in the measured data is most likely due to variation in distances to the shoreline and variable amounts of wave action along the coastal measurement locations not anthropogenic activity. Port Alma During the morning, day and evening periods, the maximum level measured was 108 db re 1 µpa. The night time levels remained steady and were similar to day time levels. These values are comparable to the rest of the Port Alma survey area suggesting that the whole Port Alma survey area experiences similar ambient background noise levels. Field observations suggest this is likely due to low levels of anthropogenic activity within the area. The Port Alma ambient noise levels were very consistent across all measurement locations including close to the existing port as well as in the open bay area. This implies that at this stage there are no noise hot spots (i.e. very little anthropogenic activity). This is in stark contrast to the Port Curtis area which is of comparable spatial extent. Rodds Bay and The Narrows Due to the comparatively low level of vessel traffic observed in Rodds Bay and The Narrows and the relative distance to Port Curtis, the baseline acoustic levels were not expected to change greatly from the March survey. The Narrows consisted of a slightly elevated high frequency component during both survey events compared with other areas, which can be seen in the difference between the received cetacean and turtle noise levels. Rodds Bay maintained the most consistent measurements for the project (both survey events) with a standard deviation of 1 to 2 db (Table 3-5 and Appendix J). 42

54 Table 3-5 Difference in db between March and June survey results Measurement area and time SPL rms average SPL rms 10% SPL rms 50% SPL rms 90% SPL rms std SPL rms Turtle SPL rms L-f Cetacean SPL rms M-f Cetacean Morning Port Curtis Daytime Evening Night Rodds Bay Morning Daytime Evening Morning Eastern Curtis Daytime Evening Night Morning Port Alma Daytime Evening Narrows Night Morning Daytime Note: Shading relates to the difference between surveys where grey shading is a decrease in SPL between surveys and no shading represents an increase Anthropogenic and Background Noise Comparison Port Curtis had the most active anthropogenic activities during the survey period, and there has been a detectable increase in these since the March survey. Activities recorded during the June survey were dominated by recreational vessels, shipping and ferry movements. No pile driving, rock dumping or dredging operations were underway at the time of the survey 2. During survey 1, the acoustic values of pile driving and rock dumping were recorded and no dredging was underway during either sampling period. As can be seen from Table 3-6 (last three columns) there is little variation (up to 5 db) in the measured received levels for each marine species for each anthropogenic noise source. The 5 db difference refers 43

55 to the difference in received SPL levels of each source for each species (i.e. difference in one column, not row). This is because the majority of acoustic energy emitted by these anthropogenic noise sources is emitted within the first kilohertz which is within the auditory bandwidths of all three species groups. It is important to note that although the received levels are comparable, the type of propulsion influences the spectral content of the measured signal (Figure 3-24). The water jet propulsion is observed to consist of higher low frequency components than that of the tinny outboard engine. The broadband noise that is heard from the water jet propulsion does not have distinguishing characteristics such as the modulated cavitation noise from a normal propeller driven vessel. This makes the water jet ferries more difficult to detect (compared to tinnies) in a high noise location such as adjacent to the RG Tanna coal terminal where low frequency ambient noise levels are relatively high. In the case of these specific sources, the nature of the noise is fairly broadband and therefore contributes relatively evenly across each species. For marine megafauna to detect an anthropogenic noise source it must have two qualities. Firstly, the noise must be above ambient noise levels and secondly the noise must have some distinctive characteristics (e.g. cavitation noise modulated by a propeller driven vessel). Similarly, if the ambient noise is very high, for e.g. close proximity to a coal terminal, detection of the noise source by the animal is greatly reduced or not possible. 44

56 Table 3-6 Results of anthropogenic noise measurement in Port Curtis M Location [Lat, Long] M time Noise source and operation spec. CPA [2] to noise source, m SPL rms Actual 50m SPL rms Turtle Actual 50m SPL rms L-f Cetacean Actual 50m SPL rms M-f Cetacean Actual 50m S E S E 16:20 18/06/ :20 18/06/2011 Water Jet Ferry Personnel Ferry S E 12:50 14/06/2011 Tugs pushing bulk carrier S 12: E 19/06/2011 Note: M = Measurement Coal Terminal with Ferry [2] CPA Closest Point of Approach. 45

57 Figure 3-24 Spectrogram of a passing tinny (left) and a passing water jet ferry (right) 46

58 Figure 3-25 Photos of common vessels in Port Curtis; a water jet ferry (top), small personnel ferry (middle) and a bulk carrier being pushed by two unseen tugs (bottom) 47

59 3.5.4 Anthropogenic Impacts on Aural Abilities In waters with high turbidity levels, such as those in Port Alma and Port Curtis and much of coastal Queensland, marine fauna rely increasingly on their hearing to forage, socialise and protect themselves from imminent threats. As Port Alma consistently has high turbidity levels, the potential impact of elevated background noise is likely to have a relatively higher impact. Where background noise increases in important habitat areas, the audible signal to noise ratio (SNR), drops making it increasingly difficult for the fauna to perform the activities critical to their wellbeing. Figure 3-26 shows the difference in overall SPL levels between the background noise and the noise of a tinny at CPA. The background and CPA levels for each area (i.e. The Narrows, Port Curtis) were extracted from the same audio file and processed individually. Figure 3-26 Comparison between background noise and the noise of a tinny As shown in Figure 3-26, even at eight times the distance from the measuring location, the difference in received SPL of a passing tinny in the Narrows is 13 db, as opposed to 4 db in Port Curtis. This small difference between background and noise source will have a direct effect on the detection time available to fauna and their subsequent response time if evasive action is required to avoid threatening processes. 48

60 Frequency Ranges of Fauna and Common Port Activities Shipping and Port Noise Pile driving Tinny Echo Sounder Turtle Hearing Dugong Hearing Dolphin Hearing Dolphin Vocalisations and Bio-Sonar Frequency Figure 3-27 Frequency ranges of some common fauna and port activities Dolphins rely on their bio-sonar as a means of navigation as well as foraging. Figure 3-27 presents the frequency range used by their sonar, which is between 10 and 100 khz. The noise emitted by tinnies (small recreational vessels) and a passing ferry near the ship load out wharf are shown in Figure 3-28 and Figure The spectrogram from the small outboard motor driven runabout is typical of the passby noise generated by cavitating propeller-driven watercraft. The spectrogram presents the underwater sound pressure as a function of time (horizontal) and frequency (vertical). The lighter the colour in the spectrogram, the higher the sound pressure received in the local environment. Because the physical origin of propeller noise is primarily a continuous series of impulsive cavitation-bubble implosions, the resultant noise is generated across a wide range of frequencies (i.e. broad band) from ~1 khz to greater than 100 khz. The bottom of the 'dip' corresponds to the point of closest approach. Either side of the point of closest approach, the distance to the vessel changes in a symmetrical fashion In contrast to Figure 3-28, Figure 3-29 illustrates a steady low-frequency underwater sound component at frequencies less than 400 Hz generated by structure-borne radiation of sound from the coal-loading wharf, and associated ships at berth. Compared to Figure 3-28, Figure 3-29 shows a less distinct vessel propeller pass-by characteristic for a slower moving vessel, this is apparent from the lower curvature of the interference pattern dip. Data analysis indicates that the RG Tanna coal wharf itself is an exceptionally loud noise source. The conveyor system (drives, idlers, etc.) injects vibration through the structure which is then re-radiated 49

61 through the pylons into the water. From the spectrograms it can be seen that the frequency content of the acoustic radiation of these sources extend all the way through that of the recorded dolphin bio-sonar. With background noise in these overlapping frequencies, it can be expected that the effectiveness of their sonar may be compromised. This has the potential to affect their bio-sonar communication and spatial awareness capabilities. Figure 3-28 Spectrogram of a passing tinny 50

62 Figure 3-29 Spectrogram of a passing ferry near the ship loadout wharf An overlap with the anthropogenic noise sources and the fauna hearing responses (Bartol 2007, Southall et al and Gerstein et al. 1999) are presented in Figure 3-27 against recorded port and construction activity, echosounder and dolphin vocalisation and bio-sonar. 3.6 Acoustic Survey Comparisons SPL levels were greater during June at most sites (Figure Figure 3-32), which may be due to more boat traffic during June. Passive observations during the second acoustic survey noted that there appeared to be more boat traffic in Port Curtis, in particular, than during the previous survey. A significant number of large equipment and dedicated contractor personnel ferries were constantly moving in and around the port, on top of the usual tinny, tug and bulk carrier movements. Several comparisons and trends can be formed between the March and June surveys undertaken. Figure 3-30 to Figure 3-32 show the comparison between the two surveys for the mid frequency cetacean, turtle and overall SPL levels for each time period. The general trend from the graphs is that there has been an increase in background levels (particularly during the day at Port Curtis), which can intuitively be attributed to increased vessel traffic. Turtle hearing range had the greatest increase (approximately 10 db) in comparison with other noise sources. Turtle hearing ranges lie within the same region as the majority of the acoustic energy from moving vessels. Therefore, an increase in vessel traffic will have the most effect on the noise received by turtles. 51

63 Survey 1 Survey Morning Daytime Evening Night Morning Daytime Evening Morning Daytime Evening Night Morning Daytime Evening Night Morning Daytime Port Curtis Rodds Bay Eastern Curtis Port Alma Narrows Tot Figure 3-30 Comparison between survey 1 and 2, overall SPL measurements Survey 1 Survey Morning Daytime Evening Night Morning Daytime Evening Morning Daytime Evening Night Morning Daytime Evening Night Morning Daytime Port Curtis Rodds Bay Eastern Curtis Port Alma Narrows Tot Figure 3-31 Comparison between survey 1 and 2, mid frequency cetacean SPL levels 52

64 Survey 1 Survey Morning Daytime Evening Night Morning Daytime Evening Morning Daytime Evening Night Morning Daytime Evening Night Morning Daytime Port Curtis Rodds Bay Eastern Curtis Port Alma Narrows Tot Figure 3-32 Comparison between survey 1 and 2, turtle SPL levels 53

65 3.7 Marine Megafauna Habitat Utilisation The inherent physiology of marine megafauna species requires close association with foraging habitats for much of their lifecycle. The dietary and social needs of the marine megafauna species groups surveyed are distinct with some overlap in ecological scale. For example, dugong and green turtles may forage extensively on seagrass habitats but in some instances resource partitioning or selective feeding may occur (Andre et al. 2005). Similar dietary scales have been observed between inshore dolphin species (Parra 2006 b and c). Differences in habitat preference may be abiotic or relative to behaviour with data from this study indicating there are some regional differences in marine environmental parameters over a relatively small spatial scale (see section 3.4). Most indicators remained consistent between sites, with the exception of Port Alma s higher turbidity (section 3.4.3) and lower salinity (section 3.4.4). When overlayed with marine megafauna presence, depth or available complex depth structure as found in most port environs may be an indicator of dolphin presence/prevalence. Other parameters such as salinity and temperature didn t show any relationship. Differences in these factors may likely have implications for the associated marine community. The observed presence of snubfin dolphins exclusively within Port Alma may suggest preference for these parameters or indeed their preferred prey species (not measured on survey or within project scope) in this project. Prey species likely play an important role in species distributions which are also closely linked to habitat characteristics like sediment types and benthos community. The Port Alma environment is distinct in hydro-geomorphology compared with other zones with considerably high flows of freshwater into the Fitzroy Delta and a depauperate benthic primary producer habitat (Lee Long et al. 1992). It also maintains the lowest levels of acoustic background noise. The figures below demonstrate the total number of sightings (on the left- axis) of marine megafauna, and the water quality parameters measured (on the right axis) in the five sampling zones. All zones surveyed had highly variable depth ranges with benthic environments structured with channels, sand banks and rocky outcrops. Across all survey events, more dolphins were observed at sites which had greater depths, as shown in Figure Port Alma and Port Curtis are port environments with dredged channels to facilitate shipping; both of these environments are steeped by tidal flats and are strongly influenced by river and creek systems. It is unlikely that depth alone is the variable that is preferred but likely a combination of variables as noted. Average temperature across both survey events did not show a relationship with marine megafauna sightings, as shown in Figure Salinity and turbidity fluctuated between sampling localities, Port Alma demonstrated relatively high turbidity and low salinity averages due to the influence of the Fitzroy River in this region. There did not appear to be an overall trend between these environmental parameters and frequency of marine megafauna sightings. Through investigations over a longer time scale, some trends may be determined between environmental parameters and marine megafauna sightings. 54

66 Observation Frequency Depth (m) Dolphin Dugong Sea snake Turtle Depth 0 Port Alma The Narrows East Curtis/Facing Port Curtis Rodd's Bay 0 Figure 3-33 Marine megafauna observations and average depth at sampling locations Observation Frequency Temperature (oc) Dolphin Dugong Sea snake Turtle Temperature Figure 3-34 Marine megafauna observations and average temperature at sampling locations 55

67 Observation Frequency Turbidity (NTU) Dolphin Dugong Sea snake Turtle Turbidity Figure 3-35 Marine megafauna observations and average turbidity at sampling locations Observation Frequency Salinity (ppt) Dolphin Dugong Sea snake Turtle Salinity Figure 3-36 Marine megafauna observations and average salinity at sampling locations 56

68 4. Discussion 4.1 Survey Coverage and Adequacy The survey included a series of aerial and boat based monitoring sites across habitats of importance to marine megafauna within a defined time frame. Summer and autumn survey dates were postponed due to prevailing poor weather resulting in unsuitable survey conditions for much of the planned survey period. The surveys enabled observations of marine megafauna species and recording of acoustic values in the study area which demonstrated the diversity of the Port Alma and Port Curtis regions. The survey has provided snap-shots in time of the numerous environmental and anthropogenic interactions that occur in this region. These snap shots are constrained spatially and temporally however; they provide an indication of environmental change and response by species to local impacts that can inform future research requirements. Despite the increase in anthropogenic activities within the port region and reported reduction in seagrass communities, animals have broadly been utilising the same habitats between surveys and years. Reduced presence of animals has been observed within the development area of Western Basin, and waters adjacent to the west of Curtis Island LNG facilities when compared with previous survey effort. Furthermore, mortality of marine megafauna by vessel strikes has occurred during the period across which the study occurred (though not observed on survey) suggesting that despite the increased presence of vessel traffic in an area of use by marine fauna, they have not been displaced entirely. Increasing the effort in these surveys would likely further inform changes in resource use by marine megafauna species. It is difficult to imply trends in the data over the limited temporal survey period, however, some important differences between surveys were observed. 4.2 Marine Megafauna Abundance and Distribution Marine Turtles in the Port Curtis Port Alma Region Gladstone Harbour and Rodds Bay are recognised as important foraging habitat for marine turtles (Dobbs 2007) as supported by the data recorded on aerial and boat-based surveys. In a regional context, the Capricorn Bunker section of the Great Barrier Reef is an important feeding habitat where green turtles graze on the seagrass beds and flatback and loggerhead turtles forage for invertebrates (pers comm. I. Bell, DERM 2008). Green turtles primarily feed on seagrass and as such, they have a predicted high association with seagrass beds and prevalence in this region. Additionally, Curtis Island is recognised as a consistent medium density nesting area for flatback turtles along the Queensland coast and low density nesting occurs by green turtles (Limpus 2007). Smaller beaches within the survey region at Hummock Hill Island and Tannum Sands also support low density marine turtle nesting. Marine turtle observations during this project were relatively frequent at the eastern Curtis and Facing Island sites during summer (n=52) and markedly less so during the autumn (n=16) boat-based survey. Rodds Bay was also observed to be a habitat of regional importance to marine turtles from aerial survey data. Habitat types such as rocky reef and offshore coastal seagrass and algae habitats have likely been less affected by adverse weather conditions in the past two years (K. Chartrand pers comm. DEEDI; 2011) which may have provided an alternative foraging habitat for turtles that previously may have utilised the inshore coastal environment. Marine turtles in the Port Curtis region have also recently been 57

69 recorded to have algae and mangrove roots within their stomach contents suggesting that supplementary food sources have been used to support local foraging populations (pers. comm. C. Limpus, 2011). As well as supporting significant foraging populations of marine turtles, islands in regional proximity (Curtis, Wild Duck and Peak Islands) to the Port Curtis development sites are recognised as medium density flatback turtle nesting habitat (Limpus 1971; Limpus et al. 1981, 1983b, Limpus et al. 2007). These islands are monitored as index beaches with some low density nesting also occurring on Tannum Sands and Hummock Hill Island. Although this survey was not undertaken during a period when nesting occurs, the region is considered to support important nesting and inter-nesting habitats which may be vulnerable to impacts (e.g. increased lighting and dredging) if not managed appropriately. Regionally, scattered aperiodic nesting for flatback turtles occurs on inshore islands and the mainland between Townsville and Torres Strait, highlighting the importance of the Gladstone region as a nesting habitat. The southern end of Curtis Island is monitored as a nesting index beach for flatback turtles. In the nesting survey, a moderate sized population was recorded with 51 nesting females noted during a two week nesting peak in late November early December. These flatback turtle nesting populations continue to indicate that the eastern Australian flatback turtle stock has had a stable breeding population over the past 36 years spanning about one generation for this species (Figure 4-1). The Curtis Island flatback turtle nesting population has maintained a relatively constant number of females over the 35 years since monitoring of the nesting females began in This constancy in size of the nesting females is consistent with the wider population not being subjected to excessive differential mortality that skews the population structure towards either reduced recruitment of new adults to the population or reduced survivorship of adults. Monitoring of nesting activity was not within the scope of this study and turtles observed on boat-based and aerial surveys are unlikely to be of nesting individuals as the surveys were out of season and nesting animals (when out of nesting season) are not often recorded within close proximity to their foraging habitats. Continued monitoring of these important nesting populations will provide an indication over time of the population size and an indication of habitat health as per the current dataset. Changes may be detected over a period of years which highlights the importance of continued data collection for informing management response (Limpus 2007). Source: Limpus (2007) Figure 4-1 Marine turtle nesting frequency for Curtis Island and Woongarra Coast,

70 4.2.2 Baseline Population Characteristics (e.g. Densities, Age-Class Structure, Indication of Reproductive Capacity 3 ) And Habitat Utilisation Population abundance estimates (as of 2009) exist for Port Curtis and Port Alma Indo-Pacific humpback dolphins and Australian snubfin dolphins (Cagnazzi, 2011). One Indo-Pacific humpback dolphin calf was sighted during the summer survey and two snubfin dolphin calves were sighted in the Port Alma region during the autumn survey. Snubfin and Indo-Pacific humpback dolphins studied extensively in other coastal areas, such as Townsville and the Great Sandy Straits, are present year round with no significant seasonal differences (Parra et al 2006, Cagnazzi 2011). Inshore dolphin calves and/or juveniles are also seen year round within Cleveland Bay, Townsville. Little is known of inshore dolphin calving times or areas that may be used for calving in the study area, so it is difficult to conclude whether the low number of calves is an indication for concern or rather a sampling artefact which would likely be resolved with increased sampling effort. Three adult dugongs were observed during boat-based surveys and one mother and calf pair was sighted during aerial surveys. Calving is an indication of population health though the calving rate needs to be sufficiently high to maintain a sustainable population. Dugong fecundity and seagrass dieback has previously been recorded to have a negative correlation (Kwan 2002). Grayson et al. (2008) found a significant negative relationship between the proportion of calves and: (1) the wet season rainfall, (2) their index of the wet season rainfall anomaly, and (3) the Southern Oscillation Index, each lagged by two years in the Northern Great Barrier Region. It is possible that similar relationships exist for other regions and this trend may be potentially observed in the next dugong aerial survey undertaken for population abundance estimates along the Queensland coast. The recorded presence of an adult dugong and calf pair on the aerial survey is a positive indication and further highlights the importance of refugial seagrass habitats in Gladstone or other regional habitats that may have persisted following the extensive wet season (2010/2011). Of the marine turtles observed on the boat-based survey (n = 68), the majority were sub-adult/juveniles. This indicates the importance of inshore coastal environments to younger turtle species where little energy is required to access sufficient food. Subsequently, it is these younger animals that are most likely to be impacted by habitat loss in coastal environments. It is possible that the intermittent impacts from development activities and reduced foraging habitat from recent meteorological events have contributed to the low number of sightings in the Port Curtis region. Offshore habitats or adjacent habitats less influenced by flooding river systems may become increasingly important when significant habitat loss of coastal systems occurs, if they are able to support appropriate dietary requirements of marine turtles. The composition of marine turtles utilising the study area will change throughout the year. When nesting adult flatback and green turtles migrate to the region for nesting (September December) they will likely have an increased presence in Port Curtis and adjacent waters (Sperling 2007). Research on nesting flatback turtles on Curtis Island (Sperling 2007) suggests that inter-nesting females enter Gladstone harbour. These flatback turtles demonstrated dive periods up to 98 minutes with a mean dive time of 50 minutes. This mean dive time for flatback turtles is approximately twice as long as commonly seen in loggerheads and other large sea turtles, while comparable to the smaller Olive Ridley (Lepidochelys 3 Note. The determination of carrying capacity of the survey area and most marine environments in general is deemed unachievable given the extensive environmental variables and numerous unknown dietary requirements, available food resources and detailed spatial use of marine fauna. This understanding is supported by numerous marine species specialists. 59

71 olivacea) and hawksbill turtle (Eretmochelys imbricata). Nesting surveys and a mark-recapture foraging study would further inform marine turtle dynamics within the project area Regional Habitat Use by Marine Megafauna Species, With Linkages to Food Chain Dynamics Food chain dynamics are complex and without undertaking substantial benthic habitat and fisheries studies or without recent (post- flooding) information available, direct inference on marine megafauna populations within the study area and their association with the prey and forage items remain undetermined. The impacts of widespread loss of seagrass habitat in Queensland (pers. Comm. R. Rasheed; DEEDI, 2011) is currently being realised with significant numbers of marine fauna species stranding (pers comm. I. Bell; DERM; 2011). This is observed to be having greatest effect on marine turtle and dugong populations given their high dependency on this resource. Anecdotal reports of increased numbers of fish entering the Gladstone Fitzroy River region due to recent floods are likely to have provided some benefit to inshore dolphin species however this has not been quantified. Benefits to inshore dolphin species may be attributed to reduced competition with higher order species for prey items or a potential increase in preferred prey species. Indo-Pacific humpback dolphins are thought to be opportunist-generalist feeders, eating a wide variety of coastal and estuarine-associated fishes, although reef, littoral and demersal fish species are taken. Teleosts, some cephalopods and crustaceans have also been recorded as prey. These dolphins have been recorded feeding in association with prawn trawlers in Moreton Bay and Gladstone Harbour and presumably elsewhere throughout the species' range in Australia (Bannister et al. 1996; Ross et al. 1994, Groom pers. obs 2009). Australian snubfin dolphin prey includes fish of the families Engraulidae, Clupeidae, Chirocentridae, Anguillidae, Hemirhampidae, Leiognathidae, Apogonidae, Pomadasydae, Terapontidae and Sillaginidae (Heinsohn 1979; Marsh et al. 1989). These fishes are typically associated with shallow coastal waters and estuaries in tropical regions (Parra et al. 2002a). Feeding may occur in a variety of habitats, from mangroves to sandy bottom estuaries and embankments to rock and/or coral reefs. Feeding primarily occurs in shallow waters (<20 m depth) and may incorporate beaching behaviour on sandbanks. Based on information obtained from the literature and baseline surveys, there are regional differences in the distribution of dolphin species within the study area. The snubfin dolphin s most southerly limit on the east coast of Australia is apparently Port Alma (Cagnazzi 2011), with no documented snubfin dolphin sighting records from the Narrows, Port Curtis or Rodds Bay in recent years. Two vagrant records of snubfin dolphins are known from the Australian east coast south of Port Alma; one individual from the Brisbane River in 1997 (Paterson 1998), one individual that was caught in shark nets off Noosa Heads (Cagnazzi 2011) and one snubfin dolphin stranding recorded on Facing Island in It is likely that snubfin dolphins are primarily targeting prey species associated with the Fitzroy River and associated Port Alma estuarine area (i.e. fishes associated with shallow coastal waters and estuaries). The reason why the snubfin dolphin distribution is restricted to Port Alma is not known yet; it may be a combination of the differentiating features between the habitat regions such as lower levels of impact, higher turbidity and faster currents and more available prey species. Port Alma also supports a network of channels and shoals with high connectivity to mangrove-lined creeks and offshore reefal areas. 60

72 4.2.4 Utilisation Significance of The Narrows by Marine Megafauna and Potential Impacts from Development Indo-Pacific humpback dolphins are more widely distributed than snubfin dolphins and are found throughout the study area. Although the duration of the summer survey was too short to establish individual ranging patterns, research by Cagnazzi (2011) indicates that the Indo-Pacific humpback dolphin population within the study area is separated into two subpopulations: Port Curtis, consisting of 86 (77-94) individuals, and Keppel Bay/Port Alma consisting of 107 (98-117) individuals. There is apparently some interchange between populations (Cagnazzi 2011), which may be facilitated by passage through The Narrows during high-tide. Cagnazzi (2011) has sighted dolphins previously within The Narrows and during summer surveys Indo-Pacific humpback dolphins were sighted at the northern and southern ends of the Narrows, indicating potential movements through this area. Inshore bottlenose dolphins were observed too infrequently to determine habitat usage patterns, specific importance of The Narrows and subsequently the potential for impacts on this species could not be determined conclusively. A section of The Narrows known as Ramsay s Creek Crossing is tidally restricted which would prevent continual movement of animals through this passage. Dugong and dolphins have been observed on aerial and boat-based surveys hundreds of metres north and south of this point with turtles observed within the immediate vicinity. The Narrows is a restricted passage between two larger open water environments. As Port Alma has not been recorded to support extensive seagrass due to its natural high levels of turbidity, it is not considered to be an area of high value to dugong and green turtles. However, it may be used as an area for transiting between preferred habitats which occur both to the north and south. The motivation for dolphins to transit between regions may be related to dietary requirements or social behaviours. Acoustic monitoring or telemetry tagging would determine the actual use of The Narrows by these species Seasonal and Inter-Annual Changes The potential to detect changes between species presence between seasons can be influenced by numerous variables and factors such as changes in turbidity, frequency of survey effort, replication, strength of the study design and use of statistics. As the first survey was conducted following an extensive wet season, turbidity was demonstrably high which would have affected aerial observations and subsequently, detection of animals below the surface. Without other datasets such as benthic habitat (seagrass) or fisheries resource data for the most recent wet season (currently unavailable, as it is still being collated), assumptions referring to differences between seasonal periods cannot be validated. Dugongs exhibit movements between habitats at several spatial scales. Large-scale movements have been observed to occur as a result of episodic loss of seagrass from events such as cyclones, floods and sedimentation (Preen and Marsh, 1995; Marsh et al. 2003; Gales et al. 2004; Marsh et al. 2004), all of which have occurred at a regional scale prior to this survey. Seasonal and inter-annual changes are therefore likely with dugong populations inhabiting the study area. As a result of these movements, monitoring of habitat is important to establish if movements are a result of anthropogenic or natural effects and indicators of seagrass-dependent species health. Parra et al. (2006a) reported that although snubfin and Indo-Pacific humpback dolphins did not use Cleveland Bay as a permanent habitat, they used the area regularly from year to year following a model of emigration and remigration. Individuals of both species would spend periods of days to a month or more in coastal waters of Cleveland Bay before leaving, and after periods of a month or more enter the 61

73 bay again. In contrast, the dolphins observed from Port Alma to Gladstone appear to be present yearround (GHD 2009b and Cagnazzi 2011). Seasonal and inter-annual changes in snubfin and Indo-Pacific humpback dolphin habitat utilisation were comprehensively investigated by Cagnazzi (2011); however, at the time of writing this report results are not yet publically available. 4.3 Impacts Potentially Associated with the Western Basin Dredging Project and Other Development in the Study Area Background The WBDDP and other development in the study area involve several activities including dredging of shipping channels and swing basins, construction of a bund wall, reclamation of intertidal habitat, pile driving and increased vessel traffic to facilitate development and construction crew movement to and from site. The impacts outlined below have been detailed to provide an understanding of impact affect to marine megafauna species as per project scope. The combined Western Basin Reclamation Area and Fisherman s Landing Expansion cover an area of ha (GHD 2009b). The reclamation area is situated on a large intertidal mudflat that extends from Fisherman s Landing to Friend Point. Dredging will occur on both sides of the South Passage Island and to the west of the North Passage Island. This project and those associated with it including the development of coastal LNG infrastructure have begun to change the Port Curtis environment which is likely to facilitate permanent change in species habitat use. Furthermore, a range of temporary impacts are expected as a result of construction activities, including dredge plume impacts, disturbance from fast transit vessels and noise impacts. A range of cumulative impacts may occur in regards to construction effects on marine megafauna species and removal of benthos in addition to existing environmental conditions. With respect to marine megafauna species, the impacts expected to result from the developments, either during construction and dredging, include: Direct impacts (observed) Removal of foraging and/or inter-nesting habitat for, marine turtle species, dugong and coastal dolphins Damage/mortality to individual animals from direct contact related to construction activities Impact to fauna by boat strike associated with the construction activities Disturbance and displacement from increased noise and/or activity during construction and dredging in the local area Increased rubbish that may be ingested or entangle marine fauna Decline in water quality from altered hydrology (in some areas reduced flushing), dredging, construction, spills of fuel or other hydrocarbons, paint, animal waste (feline pathogens) - feral or domestic, solvents and cleaners Indirect impacts (both potential and probable) Decreased water quality from construction disturbance of sediments around the Western Basin site, mobilisation of contaminated sediment An increase in sedimentation that may result in the smothering of adjacent benthic habitat communities 62

74 Degradation of habitats through continual human usage (including inappropriate waste management, boat fuel spills) Decreased water quality resulting from inappropriate waste management or an increase in sediments and pollutants as a result of construction waste or land use changes Increased lighting and noise and impacts to marine fauna from in-water construction or ongoing industry operational activities; and Reduced use of the area by marine megafauna may occur as a consequence of these potential impacts. Potential and realised impacts may have flow on effects for the value of the marine ecosystems within the Gladstone region. Additionally, when these impacts are occur concurrently, cumulative impacts result. Some of the activities have known and predicted impacts with varying levels of intensity and longevity. These are discussed in more detail below. Figure 4-2 Bund wall and associated lighting; dredgers and barges in the background Direct Impacts Mortality and Disturbance Abundance estimates such as those achieved for inshore dolphins and dugong by Cagnazzi (2011) and Marsh et al. (2005) respectively can be used to determine the Potential Biological Removal (PBR), which is the maximum level of anthropogenic mortality that can occur in a population from all causes (e.g. accidental entanglement in fishing nets or vessel strikes), while allowing the population to reach or maintain an optimal sustainable size (Wade 1998). The PBR is the product of a minimum population estimate, half the maximum rate of increase, and a recovery factor that allows for population growth and compensates for uncertainties in population estimates or responses to human impacts (Wade 1998). 63

75 The mortality limit [Potential Biological Removal (See Appendix H)] calculations for snubfin and Indo- Pacific humpback dolphins that occur within the study area show that a mortality limit of <1 dolphin per subpopulation / year is unsustainable. It is therefore important to apply a precautionary principle wherever possible to mitigate potential threats that may affect these small, localised populations. The Port Curtis region has recorded three Indo-Pacific humpback dolphin mortalities within the past four months (pers com, D. Orgill, DERM, 2011); by definition this current level of impact is unsustainable. At least one of these dolphins had been hit by a vessel in Port Curtis (pers comm. S. McCauley, Gladstone veterinarian, 2011). It is likely that the injury occurred within Port Curtis, as the population of Indo-Pacific humpback dolphins remains within a relatively small localised area (Cagnazzi, 2011); however this has not been conclusively determined. Using the PBR model, Marsh et al. (2005) estimate that if dugongs are to recover along the urban coast of Queensland, management should aim to reduce human related mortality to zero. Limitations in our ability to detect population trends arise from (1) the large variability in population estimates resulting from large-scale movements (e.g., Marsh and Lawler 2001; Gales et al. 2004; Marsh et al. 2004), and (2) the slow rate of population increase for dugongs (Marsh 1995; Marsh 1999). An increase or decline in the population can only be detected if aerial surveys are conducted over many years and, therefore, a declining population may reach a critically low level before it is detected (Marsh 1995). The long-term aerial survey program along the Queensland urban coast has provided critical information about dugong distribution, abundance and trends. However, in the short-term, population estimates can be valuable when assessed in combination with known mortality rates from human impacts. This survey highlights Port Curtis as the location in the study area with the highest presence of dugong and levels of background noise. Significant noise sources such as pile driving and vessels contribute substantially to the noise spectrum within the region. When these activities are operating in isolation or with marine fauna species being a sufficient distance from the source, these activities are unlikely to significantly impact; however, when these sources are combined or other pile driving activity is underway the direct exposure risk to marine fauna subsequently increases. It is plausible that the observed high levels of background noise have reduced the potential for animals to detect on-coming traffic; speed is also recorded to directly influence detection time by marine megafauna species (Hodgson 2007). No wash zones are currently in place for areas near existing infrastructure however; these limits do not extend to other areas of frequent and high speed vessel transit (vessels used most frequently to transit work crew to and from Curtis Island). If disturbance is prevalent over important areas of habitat there may be consequential impacts to feeding, breeding and communication, which may in turn have an impact at the population level if persistent and alternative refugial habitat is not available in adjacent areas. Dredging From the literature, the nature of dredging noise is that it occupies the mid to low frequency range and is tonal and continuous. While there is little specific information relating to the sensitivity of cetaceans and dugongs to dredging noise, there is a trend in the information that indicates that dredging is not considered to pose a significant risk. While the noise from dredgers is within the hearing frequencies of larger cetaceans, it is considered to increase ambient noise levels, but not cause undue interference or stress. It is thought that dugongs may have limited perception of dredger noises at such low frequencies (URS 2004). Underwater noise from dredging is likely to result in marine mammals avoiding the dredging area; however, marine mammals may exhibit tolerance to such noise and may come into close proximity 64

76 to construction activities as a consequence of acclimating to the noise or out of curiosity. Although there is evidence that masking of other noises due to the noise from dredging activity is not likely to be biologically significant to marine mammals, there is potential for turtles to be harmed or killed by dredging activity if appropriate mitigation measures are not implemented. Figure 4-3 Indo-Pacific humpback dolphins observed in the early evening at Port Curtis 65

77 Figure 4-4 Jet skis travelling through the Narrows Habitat Loss The dredging and development activities currently underway for this region will directly change the current habitat form and seagrass removal will occur. This habitat supports a diversity of invertebrate and fish communities. It will be replaced by deeper channels that may provide an aggregation area for some larger fish species and potential resting areas for some marine turtles. Dolphins have been frequently observed to occur in the channels however, as industrial activity in this region increases the use of the channels may subsequently decline. The construction of bund walls and gas terminal infrastructure will shift the current habitat from a soft sediment environment to a hard substrate environment allowing potential for other species (algae and coral) to colonise which may in turn support other species. Before colonisation occurs there will be a lag period where foraging habitat has been lost from the local site, which will mean species currently using this area for feeding will be displaced to other habitats. The communities that subsequently develop will be different to those that originally occupied the area which could also affect the presence of higher order taxa. Species with high levels of site fidelity, such as those discussed in this report, are vulnerable to population declines as a result of habitat degradation and loss, particularly when those species occupy relatively restricted habitats (Warkentin and Hernandez 1996). Such site fidelity potentially conveys several ecological benefits including reduction in the costs and risks involved in relocating to new sites, and familiarity with resources and predators (Greenwood 1980). Dugong, marine turtles, snubfin and Indo-Pacific humpback dolphins transit throughout coastal waters regularly from year to year (Parra et al. 2006, Marsh et al 2005, Preen 2000). However, some animals within these species groups have been observed to maintain small-scale movements only (Cagnazzi 2011 and Sheppard 2006) thus increasing 66

78 the direct impact on habitat at a local scale. The regional loss of habitat confounds this impact by reducing available habitat within an animal s ecological scale which may have been used as refuge. Vessel Traffic High vessel traffic in shallow coastal areas can cause serious injuries and mortalities to coastal dolphins dugong and turtles (Greenland and Limpus 2006, Groom et al. 2004, Wells and Scott 1997, Parsons and Jefferson, 2000), reduce their access to particular areas within their home range (Allen and Read 2000), affect their acoustic communication (Van Parijs and Corkeron 2001), and alter their behaviour (Lusseau 2003; Constantine et al. 2004). All of these effects can be potentially detrimental to all marine fauna species in Port Curtis and particularly so for small populations of dolphins inhabiting Rodds Bay. In the past five years in Queensland, boat strike has been the leading cause of mortality in turtles and dugong (Greenland et al. 2004, Greenland and Limpus 2007). Boat traffic associated with the proposed Project development (including dredging activities) will create a temporary increase in vessel traffic during construction and provide potential for future permanent increases in vessel traffic to the reclaimed site. Vessel traffic is also likely to increase as a result of general population increase in Gladstone over time. The potential for boats to displace marine fauna and disrupt their behaviour is well documented (Van Parijs and Corkeron 2001; Bejder et al. 2006a; Bejder et al. 2006b; Lemon et al. 2006; Hodgson and Marsh 2007). The acoustic communication and group cohesion of Indo-Pacific humpback dolphins is affected by boat traffic and noise. Mother-calf group cohesion has been recorded to be affected by vessel traffic, with an increase in whistles indicating that the groups needed to re-establish acoustic contact after the disturbance (Van Parijs and Corkeron 2001). Boat traffic has both direct lethal impacts as well as indirect habitat quality impacts on the surveyed marine fauna species. The incidence of marine fauna and harmful boating interactions is rapidly increasing relative to the increase in boat traffic along the urban coastline in Australia. In Gladstone, the number of registered boats has been observed to steadily increase each year for the past 10 years (Figure 4-5), and proportionally, vessel ownership and the level of on-water vessel boating is also increasing ( 67

79 Source: (2011) Figure 4-5 Total registered vessels within the Gladstone Regional Council Boat strikes are a significant cause of dugong and turtle (particularly green turtles) mortality in Australia (Greenland and Limpus 2006), and their delayed response to boats makes them particularly vulnerable to large, high speed vessels (Groom et al. 2004; Hodgson 2004, Hazel and Gyuris, 2006). The risk of boat strikes to marine mammals and turtles increases as the density of boats increases. The relationship between boat density and the risk of boat strikes is particularly well illustrated in Florida where the number of vessel strikes on marine mammals has increased in conjunction with increasing vessel registrations (Ackerman et al. 1995). The risk of boat strike is not only determined by the density of animals within an area, but also characteristics of boat traffic and the marine environment, including: Vessel size (draft and mass) Vessel speed Average number of vessels transiting Bathymetry (Hodgson 2004) In Moreton Bay for example, the highest number of boat strike mortalities occur within an area of low dugong densities but where large, high speed ferries are repeatedly transiting (Groom et al. 2004; Hodgson 2004; Greenland and Limpus 2006). Vessel speed is a contributing factor in the risk of vessel strikes to marine turtles and marine mammals. The faster the vessel, the less time the animal has to take avoidance action and the greater the force of impact. Water depth affects the potential for boat strike as in shallow waters the animals cannot evade boats by diving and dugongs are known to have been crushed between boats and the water bottom (Yeates and Limpus 2003). With increased development in 68