Ashmore Reef Sea Snake and Turtle Proposal.docx · Web viewAshmore Reef Sea Snake and Turtle Proposal.docx Ashmore Reef Sea Snake and Marine Turtle Proposed Survey ABSTRACT The project

ASHMORE REEF SEA SNAKE AND

TURTLE PROPOSAL.DOCX

Ashmore Reef Sea Snake and Marine Turtle Proposed SurveyABSTRACTThe project aims to survey the sea snake and marine turtle populations at Ashmore Reef. This is in response to the drastic and unexplained decrease in sea snake numbers and diversity at Ashmore reef in the last decade. The nests of marine turtles on West Island have been attacked by invasive species of exotic ants which reduced their hatching success.

Mick Guinea34 Cornwallis circuit Palmerston 0830 NT Mobile :0438192507e-mail:[email protected]:57 485 603 219

Ashmore Reef Sea Snake and Marine Turtle Proposed Survey

INTRODUCTIONAn assessment of sea snake and sea turtle numbers at Ashmore Reef requires an extensive knowledge of the shallow water reef-flat and shoreline habitats and the species involved. The Principal investigator has monitored sea snake and marine turtle populations and the changes to their habitats in the Sahul Shelf region since 1992. Much of the information has been published in various reports and journal articles, although some descriptive information remains unpublished amongst the field notes from the various surveys. The studies have been multidisciplinary in nature focusing on aspects of sea snake and marine turtle biology and management.

The focus of this proposal is a survey of the sea snakes and marine turtles of the islands and reefs of the Ashmore Reef Marine Park. The surveys will be conducted during a common period of data collection with spatial and temporal separation for each of the fauna under investigation. The data set produced will provide statistical comparisons over a spatial and temporal framework. Comparisons with sea snake and sea turtle populations at Cartier Island can be accomplished should transport to and “permits to enter” be obtained.

Sea SnakesThe proposal uses in-water surveys of sea snakes in and around the reefs Ashmore Reef and Cartier Island. These are both continental shelf-edge reefs bordering the Indian Ocean. Studies into sea snake numbers and species diversity commenced in 1992 at Cartier Island and Hibernia Reef (Guinea 1993). Surveys of sea snakes included Ashmore Reef in 1994 (Guinea 1995, 2006, 2007, 2008), with subsequent visits in 1996, 1998 and 2000, 2003, 2005 (Guinea 1995, 2006, 2007, 2008. Surveys of Scott Reef for sea snakes were conducted in 1994 (Guinea 1995) and 2006 with Seringapatam Reef as part of sea snake and marine turtle monitoring for environmental consultants URS and SKM. Hibernia Reef and Ashmore Reef have similar sea snake species diversity (Minton and Heatwole 1975) may be due to each reef system being in close proximity and containing a definite reef front surge zone with a sheltered deep lagoon with sand banks (Russell and Hanley 1993 , Guinea and Whiting 2005). Cartier Island consists of a small sand cay with extensive reef flat without a lagoon. Its sea snake assemblage is reduced slightly as it lacked the Ashmore Reef endemic species (Leaf-scaled and Short-nosed sea snakes). Scott and Seringapatam Reefs had fewer species than Ashmore Reef but large and easily assessed populations of Olive, Dusky and Turtle-headed sea snakes (Table 1).

Historically Ashmore Reef and Hibernia Reef had very similar sea snake species assemblages (Minton & Heatwole 1975, Guinea 1995). However, in more recent years, the numbers of species of sea snakes recorded from Ashmore Reef has decreased to a similar species assemblage to Scott Reef (Francis 2006, Guinea 2008), By 2013 the sea snake population at Ashmore Reef had dwindled to a low level and was below survey detection (Guinea 2013, Lukoschek , Beger et al. 2013).

Table 1 Distribution of the common reef-dwelling sea snake species on the shelf edge reefs of the Sahul Shelf.Species Ashmore

ReefHibernia

ReefCartierIsland

Seringa- patam Reef

Scott Reef

Leaf-scaled Seasnake

√ √

Dusky Seasnake

√ √ √ √

Short-nosed Seasnake

√ √

Olive Seasnake √ √ √ √ √

Horned Seasnake

√ √ √ √

Stokes’ Seasnake

√ √ √

Dubois’ Seasnake

√ √ √

Turtle-headed Seasnake

√ √ √ √ √

Marine TurtlesThree species of marine turtles are regular inhabitants of the reefs of the Sahul Shelf. Green turtles are the most noticeable species because they feed on the seagrass in shallow water and nest on the beaches on West Island, Ashmore Reef (Guinea 1993, Guinea 1995, Whiting and Guinea 2005, Whiting and Guinea 2005) Cartier Island (Guinea 1993, Guinea 2013). Hawksbill sea turtles feed in the lagoons and on the reef crest of all the reefs of the Sahul Shelf. They nest on Middle and East Island, Ashmore Reef. Loggerhead sea turtles feed on molluscs and echinoderms on the reef flat at Ashmore Reef with a single report of nesting on West Island (Whiting & Guinea 2005).

Preliminary estimates of sub-adult turtles on Ashmore Reef were 61.6 animals per hectare which when extrapolated over the reef flat reached 10,714 sub-adult green turtles for Ashmore Reef (Guinea 1995, Whiting & Guinea 2005). Studies of the productivity of the reef flat at Ashmore Reef (Brown and Skewes 2005) revealed the seagrass beds were capable of supporting such a population. Ashmore Reef has the most extensive seagrass and algal flats of the reefs of the Sahul Shelf and correspondingly a large number of feeding green turtles. These attributes make it a reference area for green turtle genetics (Dethmers, FitzSimmons et al. 2005) and standard blood chemistry reference values (Whiting, Fomiatti et al. 2007). Sub-adult turtles that feed on the seagrass and algae on Ashmore Reef comprise a large percentage of turtles from the North West Shelf gene pool (Dethmers, FitzSimmons et al. 2008). The nesting turtles at Ashmore Reef and Cartier Island form a distinct gene pool (Dethmers et al. 2008). Plasma samples from 59 sub-adult green turtles were analysed and the components correlated with their diet at Ashmore Reef (Whiting et al. 2007). This combination of known genetic stock and previous blood analysis on a known diet

identifies Ashmore Reef and its turtles as a reference population for other studies of blood chemistry in green turtles (Arthur, Limpus et al. 2008, Flint, Morton et al. 2009, Flint, Limpus et al. 2010).

From 1987 to 2004, 565 nesting green turtles have been tagged at Ashmore Reef along with 402 foraging sub-adult green turtles (Whiting & Guinea 2005). The surveys included assessments of the success of nesting females in depositing their eggs, the success of hatchlings emerging from the nest as well as the detrimental impact of introduced and native predators. These indicators of population health and the numbers of nesting and foraging green turtles provide an indication of the stability of the nesting and foraging populations of sea turtles.

This survey will record the presence and numbers of marine turtles in the shallow reef habitats. The survey techniques are non-invasive all animals will be released at the point of capture. No animal will be removed from the water or the beach. None will be diverted from their normal behavior. These procedures for marine turtles and sea snakes are covered by existing Animal Ethics Approvals from Charles Darwin University.

Study Objectives

The proposal aims to assess the presence and population status of sea snake and marine turtles at Ashmore Reef.

1. To quantify the presence of EPBC listed fauna (sea snakes and marine turtles) at Ashmore Reef.

2. To identify and quantify the species of sea turtle and their respective numbers nesting on the islands and sand cays of Ashmore Reef.

3. To identify and quantify the species of sea snakes and their respective numbers and density on the reefal habitats at Ashmore Reef

4. To identify and quantify the hatching success of the species of sea turtle nesting on the islands and sand cays of Ashmore reef.

5. To identify and quantify the effect of predators of sea turtle nests laid on the islands and sand cays of Ashmore Reef

6. Should permits and transport be available to make a comparative but much shorter survey of the EPBC listed fauna at Cartier Island.

METHODS

The waters close to the shoreline will be examined to a depth of 10 metres visually with photographic records taken of general reef vistas and specific items of biota or habitat that may indicate a recent impact.

Two localities will be surveyed for sea snakes, sea turtles and for collections of data for general habitat assessment.

Ashmore Reef is an area of probable or possible impact from the release. This reef has an extensive intertidal reef flats with dynamic sand deposits and two large lagoons and many kilometres of reef edge habitat. Three vegetated sand islands lie along the east-west axis of the reef approximately 8 km from their nearest neighbouring island.

Cartier Island is approximately 60 km south-east of Ashmore Reef. This reef lacks a lagoon but has a relatively uniform reef flat and a well-defined reef crest. An un-

vegetated sand cay sits near the middle of the reef.

Survey Techniques

Manta Board SurveysManta board surveys have been used on Ashmore Reef, Cartier Island and Hibernia Reef in previous research trips (Guinea 1993; Guinea et al. 2004; Guinea 2006; 2007, 2013). Manta boards are a standard survey tool of the Australian Institute of Marine Science (Done, Kenchington et al. 1982, Fernandes 1990, Fernandes, Marsh et al. 1990, Moran and De'ath 1992, English, Wilkinson et al. 1994).

The manta board consists of two pieces of wooden ply each attached to 25 m of 4 mm polypropylene rope and connected to the transom of a dinghy. Tow speed is 4 km/hr (2 knots) measured by GPS. The tow rope has coloured twine markings at 5 m intervals to gauge underwater visibility. Two snorkelers are towed simultaneously side by side. Each is responsible for recording sea snakes and marine turtles on their respective side of the path. A Perspex slate and pencil enable notes to be made at minute intervals that correspond to the approximate length of 67 metres of survey. Start and finish locations are recorded with GPS by the boat crew, along with the time.

Boat crew consist of a coxswain and an observer facing the stern and in visual contact with the snorkelers. Hand signals and communications are in accordance with Australian Institute of Marine Science protocols English, Wilkinson et al. 1994).

Manta board surveys of sea snakes and marine turtles will be conducted in shallow waters to 10 m in depth. The surveys will be in daylight hours at a time when underwater visibility is at its best. Each manta board survey will last 15 minutes. Consecutive surveys are possible but each 15-minute interval is recorded separately. The boat crew will collect the GPS points at the start and finish of the survey and the respective times. The snorkelers will collect data on the time interval of the survey, the number of sea snakes and marine turtles seen and their respective life stage (adult or immature). The sex of the marine turtles will be recorded as those having a long tail (adult males) or having a short tail (females and immature males). All data will be collected so that it may be entered into a GIS.

Snorkelers may release the manta board to examine sea snakes more closely for identification. Photographs will provide the visual record of the species. No animals will be taken from the wild and none will be taken aboard the contract vessel.

A stratified random survey will be conducted on each reef. Surveys will be conducted of the reef crest on windward and the leeward of each reef. Surveys will also be conducted on the reef flat in seagrass beds and over bare sand. The lagoons, back reef channels and isolated bommies, where present, will also be surveyed. Each habitat on each reef will have three surveys each with two observers.

Standard Snorkel Surveys

Surveys on snorkel will be conducted during daylight hours in the vicinity of the contract vessel’s tender. Observers present in the tender will record GPS locations and time. Sea snakes that cannot be identified from a distance will be captured for close examination and photographic recording. Snorkelers swim or drift between the two points recorded by GPS so that the area surveyed is recorded. All sea snakes seen along the transect line will be, examined, photographed and GPS position recorded.

Sea Snakes

Sea snakes will be identified from the pictorial keys, videos and photographs. Individual sea snakes will be assessed for general health and condition. A photographic index of individual sea snakes will be compiled. Records will be made of any mating or feeding behaviours of sea snakes observed during the in-water surveys. Sea snake densities will be recorded as captures or sightings per unit time and per area of reef habitat examined in each habitat.

Marine TurtlesThe green turtles (Chelonia mydas) at Ashmore Reef comprise at least two distinct genetic stocks (gene pools). The nesting turtles are of Ashmore Reef and Cartier Island origin. Having been hatched from nests on these islands, the females return as adults some decades later to the region of their birth for nesting. This fidelity to a nesting area produces a genetically distinct and geographically restricted metapopulation that breeds only within the gene pool.

The foraging green turtles are a mixture of gene pools. Individuals feeding on Ashmore Reef are from a number of different metapopulations. Almost 70% of small (<60 cm) green turtles belong to the North West Shelf gene pool (Lacepede Islands to Ningaloo Reef) another 20% are from Scott Reef (Dethmers et al. 2005). These turtles remain on Ashmore Reef feeding on algae and seagrass for some years or even decades before moving to other locations on their developmental migration along the north Australian coast and into Indonesia (Whiting & Guinea 2005).

Foraging Marine TurtlesFeeding turtles will be surveyed by boat at high tide on the reef flat. The survey consists of an observer on the port and another on the starboard side of the vessel. The coxswain steers a straight course between two known GPS points at a constant and safe speed. Sea turtles are identified to species, life stage and their perpendicular distance from the path of the vessel (transect line) recorded. Amongst the feeding aggregation of green turtles are a number of sub-adult loggerhead turtles and dugongs. Loggerheads feed on molluscs and sea cucumbers on the reef flat. The positions of any loggerheads that are encountered will be recorded. Dugongs feed on algae and sea grass on the reef flat at high tide. The positon of any dugongs seen will be recorded.

Nesting Marine TurtlesMarine turtles nest on all three islands and sand cay at Ashmore Reef as well as on Cartier Island. Green turtles are the more common nesting species on Cartier Island and West Island. Hawksbill turtles nest on Middle, East Island and also West Island on Ashmore Reef. The islands will be examined for recent marine turtle nesting and signs of hatched nests. All recent nests will be identified to species by the tracks of the female and recorded with GPS receiver. All hatched nest will be excavated and the contents recorded into the following categories: number of shells, live hatchlings, dead hatchlings, undeveloped eggs, unhatched eggs and emerged hatchlings. From these data the hatching and emergence successes are calculated. Hatched and fresh nests will be examined for the presence of ants that may be detrimental to the survival of the nest.

West Island will be patrolled at night with ambient moonlight and starlight sufficient to gain a clear view of the beach. When ambient light is insufficient for monitoring, a red light emitting diode (LED) headlamp (Energizer HDL33A) will be used to illuminate the path ahead of the

survey team over sand and beach rock areas of West Island. The light will be limited to the smallest possible area so as to not influence the behaviour of nesting turtles.

When the nesting turtles have finished laying and are returning to the water, they will be checked for tags. If no tags are present they will be tagged with a two, individually numbered, 4.1-gram titanium tag (CA series) attached through the axillary scale (closest to the body) of the left and right front flipper. Carapace dimensions and any individual distinguishing marks or injuries will be recorded for each adult turtle. Curved carapace lengths (CCL) and curved carapace widths (CCW) will be measured with a flexible fibreglass tape (± 0.05 cm). The CCL is measured from the junction of the skin and the nuchal (most anterior carapace) scale to the notch between the post vertebral scutes at the posterior of the carapace (Limpus, Carter et al. 2001, Limpus and Limpus 2001, Limpus, Miller et al. 2003, Guinea, Whiting et al. 2005, Guinea 2013). The CCW is measured across the carapace at its widest point with the same tape.

All tag data will be entered in the department of environment sea turtle tag database. A nightly summary will record the number of turtle tacks on West Island, the number of nest laid and the number of turtles carrying previous tags and the number of turtles freshly tagged and the number of hatched nests for each species.

PersonnelThe survey team will consist of three persons. The participants will be drawn from the pool of 12 persons trained in manta board surveys, sea snake identification, marine turtle identification and also have experience in tagging and recording nesting marine turtles. All will have SCUBA qualifications and completed TBOSIET certification. Note this proposal does not utilize SCUBA. Each will have current First Aid certifications and experience in small boats.

Budget:

I have produced a costing for a two person and a three-person trip ar requested. The hourly rates are based on the current CDU salary book to ensure some parity with other universities should they be asked to submit a similar proposal.

For a single 18-day trip:

Field Work and Preparation Report WritingTotal  GST 10%

Total including GST

2 persons  $24,152.10 $10,344.60 $34,496.70 $3,449.67 $37,946.373 persons $32,787.30 $10,344.60 $43,131.90 $4,313.19 $47,445.09For two trips in the year the costs will double.

Total GST 10%

Total including GST

2 persons $68,993.40 $6,899.34 $75,892.743 persons $86,263.80 $8,626.38 $94,890.18

The port of embarkation is Darwin. The team will be led by Principal investigator and the participants will be experience in turtle tagging and recording sea turtle nesting and feeding

numbers and manta board surveys for sea snakes.

The 3-person team is the preferred option because the Standard Operation Procedures requires an observer on the boat during manta tows.

References:

Arthur, K. E., C. J. Limpus and J. M. Whittier (2008). Baseline blood biochemistry of Australian green turtles (Chelonia mydas) and effects of exposure to the toxic cyanobacterium Lyngbya majuscula. Australian Journal of Zoology 56(1): 23-32.

Brown, K. and T. D. Skewes (2005). A preliminary assessment of the ecology of seagrasses at Ashmore Reef. The Beagle Supplement 1: 143-152.

Dethmers, K., N. FitzSimmons, D. Broderick, S. Whiting, M. Guinea, R. Kennett, M. Hamann and C. Limpus (2005). Distribution of green turtle ( Chelonia mydas) populations across North Australian feeding grounds. 25th Annual Symposium on Sea Turtle Biology and Conservation, in press.

Dethmers, K. E. M., N. N. FitzSimmons, D. Broderick, S. D. Whiting, M. L. Guinea, R. Kennett, M. Hamann and C. J. Limpus (2008). Distribution of green turtles (Chelonia mydas) populations across North Australian feeding grounds. Proceedings of the Twenty-Fifth Annual Symposium on Sea Turtle Biology and Conservation. NOAA Technical Memorandum NMFS-SEFSC-582. 204 pp.

Done, T. J., R. A. Kenchington and L. D. Zell (1982). Rapid, large area, reef resource surveys using a manta board. Proceedings of the Fourth Coral Reef Symposium 1, .

English, S., C. Wilkinson and V. Baker (1994). Survey Manual for Tropical Marine Resources, 2nd Edition. Townsville, Australia, Australian Institute of Marine Sciences.

Fernandes, L. (1990). Effect of the distribution and density of benthic target organisms on manta tow estimates of their abundance. Coral Reefs 9: 161-165.

Fernandes, L., H. Marsh, P. J. Moran and D. Sinclair (1990). Bias in manta tow surveys of Acanthaster planci. Coral Reefs 9: 155-160.

Flint, M., C. J. Limpus, P. C. Mills, J. M. Morton and J. C. Patterson-Kane (2010). Reference intervals for plasma biochemical and hematologic measures in loggerhead sea turtles (Caretta caretta) from Moreton Bay, Australia. Journal of Wildlife Diseases 46(3): 731-741.

Flint, M., J. M. Morton, C. J. Limpus, J. C. Patterson-Kane, P. J. Murray and P. C. Mills (2009). Development and application of biochemical and haematological reference intervals to identify unhealthy green sea turtles (Chelonia mydas). The Veterinary Journal 185(3): 299-304.

Francis, E. J. (2006). The Morphology, Population and Distribution of the Dusky Sea Snake Aipysurus fuscus (Tschudi, 1837) . BScHons, Charles Darwin University.

Guinea, M. L. (1993). Reptilia, Aves and Mammalia. Survey of Marine Biological and Heritage Resources of Cartier and Hibernia Reefs, Timor Sea. B. C. Russell and J. R. Hanley. Darwin, Northern Territory Museum of Arts and Sciences: 74 - 83.

Guinea, M. L. (1995). The Sea Turtles and Sea Snakes of Ashmore Reef National Nature Reserve. Darwin, Northern Territory University.

Guinea, M. L. (2006). Final Report Survey 2005: Sea Snakes of Ashmore Reef, Hibernia Reef and Cartier Island. Darwin, Charles Darwin University.

Guinea, M. L. (2007). Sea Snake Survey of Ashmore Reef, Hibernia Reef and Cartier Island with comments on Scott Reef March 16 -April 2 2007:Final Report Darwin, Charles Darwin University.

Guinea, M. L. (2008). Sea snakes of Ashmore Reef and Cartier Island DEWHA Final Report Survey 2008. Darwin, Charles Darwin University.

Guinea, M. L. (2013). Surveys of the Sea Snakes and Sea Turtles on Reefs of the Sahul Shelf Monitoring Program for the Montara Well Release Timor Sea: MONITORING STUDY S6 SEA SNAKES / TURTLES, School of Environment, Charles Darwin University.

Guinea, M. L. and S. D. Whiting (2005). Insights into the distribution and abundance of sea snakes at Ashmore Reef. The Beagle (Supplement 1): 199-206.

Guinea, M. L., S. D. Whiting and A. U. Koch (2005). Nesting turtles of Ashmore Reef. Sea turtles of Ashmore Reef: History, Current Status and Future Directions of Research and management. S.

D. Whiting and M. L. Guinea. Canberra, Department of the Environment and Heritage: 91-114.Limpus, C. J., D. Carter and M. Hamann (2001). The green turtle, Chelonia mydas, in Queensland,

Australia: the Bramble Cay rookery in the 1979-1980 breeding season. Chelonian Conservation and Biology 4(1): 34-46.

Limpus, C. J. and D. J. Limpus (2001). The loggerhead turtle, Caretta caretta, in Queensland: breeding migrations and fidelity to a warm temperate feeding area. Chelonian Conservation and Biology 4(1): 142-153.

Limpus, C. J., J. D. Miller, C. J. Parmenter and D. J. Limpus (2003). The green turtle, Chelonia mydas, population of Raine Island and the northern Great Barrier Reef: 1843-2001. Memoirs of the Queensland Museum 49(1): 349-440.

Lukoschek V, Beger M, Ceccarelli D, Richards Z and P. M (2013). Enigmatic declines of Australia's sea snakes from a biodiversity hotspot. Biological Conservation 166: 191-202.

Minton, S. A. and H. Heatwole (1975). Sea snakes from three reefs of Sahul shelf. The biology of sea snakes. W. A. Dunson. Baltimore, London & Tokyo: 141-144.

Moran, P. J. and G. De'ath (1992). Suitabliity of the manta tow technique of estimating relatiave and absolute abundances of crown-of-thorns starfish (Acanthaster planci L.) and corals. Austalian Journal Marine Freshwater Research 43: 357-378.

Russell, B. C. and J. R. Hanley (1993 ). The marine biological resources and heritage values of Cartier and Hibernia Reefs, Timor Sea. Northern Territory Museum of Arts and Sciences Darwin .

Whiting, S. and M. Guinea (2005). The sea turtles of Ashmore Reef: history, current status and future direction research and management, Biomarine International & Charles Darwin University

Whiting, S. D., K. Fomiatti, M. L. Guinea and C. J. Limpus (2007). Blood chemistry reference values for two ecologically distinct populations of foraging green turtles, eastern Indian Ocean. Comparative Clinical Pathology16(2): 109-118.

Whiting, S. D. and M. L. Guinea (2005). Sea turtles of Sahul Banks -work completed and required. The Beagle (Supplement 1): 248.