Rec. West. Aust. M"... Suppl. No. 44.1993 Part 1

Historical background, description of the physical environments of Ashmore Reef and eartier Island and notes on exploited species

P.F. Berry*

Abstract Ashrnore Reef (12°17'S, 123°02'E) and nearby Cartier Island (l2°32'S, 123°33'E) are located on tl.e north-western extremity of the Sahul Shelf. They are approximately 350 km off the Kimberley coast of Australia and 145 km from Roti, Indonesia. The morphology and physical environments of the two reef systems are briefly described as a background to faunal inventories presented in Parts 2-7 ofthis publication. Ashrnore Reef (approximately 26 km long and 14 km wide) is similar in general shape and morphology to other shelf-edge atolls off the north-western coast of Australia, but because of the larger breaks in the reef there is no impounding of water in the lagoon on outgoing tides as at the Rowley Shoals and to a lesser extent, Scott Reef. There are three vegetated islets on Ashmore Reef. Cartier Island, an unvegetated sand cay, is surrounded by an oval-shaped reef platform approximately 4.5 km long by 2.3 km wide. Mean sea surface temperatures range from approximately 24°C in July and August to 30°C between January and March. Spring and neap tidal ranges (semi-diurnal) are 4.7 m and 2.8 m respectively. Observations on species exploited in the traditional Indonesian fishery are recorded. These suggest that composition and abundance of exploited species at Ashmore Reef and Cartier Island reflect a higher level of fishing effort there than at Scott Reef and Rowley Shoals.

Introduction Ashmore Reef (12°17'S, 123°02'E) and nearby Cartier Island (12°32'S, 123°33'E) lie on the north-western extremity of the Sahul Shelf 350 km off the Kimberley coast (Figure 1). They are separated from Indonesia (Roti) by the Timor Trough and a distance of approximately 145 km. To the north-east is an extensive and complex system of submerged reefs (the Sahul Banks), some of which are buried in sediment, while others are exposed and reach within 6 m of surface; only Hibernia Reef is emergent. This reef system must once have been comparable to parts of the Great Barrier Reef (Edgerley 1974). To the southwest lies a series ofatolls rising from the continental slope: Seringapatarn Reef, Scott Reef and the Rowley Shoals, for which faunal inventories have been published (Berry 1986). This report describes the results ofa preliminary survey of selected faunal groups at Ashmore Reef and Cartier Island by the Western Australian Museum in September 1986 and also lists the faunas of all these shelf-edge reefs sampled so far. Collections of octocorals and echinoderrns from Ashmore Reef made by the Northern Territory Museum between 1986 and

* Western Australian Museum, Francis Street, Perth, Western Australia 6000. Physical enviromnent

/ N o / A N

o c EA N

o 100 200 300 I I I I km

WE s TER N AUST RA LIA

Figure 1 Map ofthe shelf offnorth-western Australia. 1987 have been included. Participants in the survey were: G. Allen (fishes), P. Berry (crustaceans, leader), C. Bryce (molluscs, technical), T. Knight (medical), L. Marsh (echinoderms, cnidarians other than reef-building corals), J. Veron (reef-building corals) and F. Wells (molluscs). Historical Notes Because of their proximity to Roti, Ashmore Reef and to a lesser extent Cartier Island have been for centuries and still are, visited by Indonesian fishermen in traditional sailing prahus.

2 P.E Berry

They are also staging posts for longer voyages to other reefs and islands off the Kimberley coast and to the coa<;t itself (MacKnight 1976). The position of Ashmore Reef was reported by Captain S. Ashmore on the Hibernia in 1811 and Great Britain took formal possession of it on behalf of the Western Australian Government in 1878. In the same year it was also claimed on behalf of the United States of America by Captain Webber who referred to it (the three islands) as "the Caller Group" (after his vessel Sadie F. Caller) and a dispute arose as to the rights to mine guano deposits there. However, the United States Government did not support Webber's claim. Carrier Island was annexed by Great Britain in 1909. In 1931 Ashmore Reef and Carrier Island were placed under the authority of the Commonwealth of Australia as an External Territory (the Territory of Ashmore and Carrier Islands) administered until 1938 by Western Australia, then by the Northern Territory until 1978 when control was returned to the Commonwealth. In 1974 a Memorandum of Understanding was signed by the governments of Australia and Indonesia which allowed continuation of certain traditional Indonesian fishing at Ashmore Reef and Carrier Island. In 1983 Ashmore Reef and surrounding waters to approximately the 50 metre depth contour were declared a National Nature Reserve under the National Parks and Wildlife Conservation Act of 1975. The position of Carrier Island was rust reeorded in 1799 by Captain Nash on the vessel Cartier. Little has been published on the marine fauna of Ashmore Reef and Carrier Island. In 1952 Serventy provided a list of birds encountered on his visit in 1949, although he did not land at Carrier Island. The 1972-73 visit by the US Alpha Helix resulted in a small colleetion offishes, deposited at the Scripps Institute of Oceanography and a publication on the seasnake fauna (Dunson 1975). In 1978 the USSR vessel Professor Bogorov visited Ashmore Reef, resulting in an unpublished report on the echinoderm fauna and reeording the presence of four genera of Alcyonacea (Anon. 1979). Attempts to obtain the results of fauna sampling the same year by the USSR vessel Kallisto were unsuccessful. Reports produced by staff of the National Parks and Wildlife Service and Western Australian Department ofFisheries cover mainly birds, turtles, dugongs and seagrasses (e.g. Forbes 1982; Hicks 1982, 1983; Sarti 1983).

Physical Environment The climate is monsoonal with a prevailing westerly and northwesterly rainbearing monsoon from November to March and dry southeasterly trade winds from May to September. No rainfall figures are available. Ashmore reef lies to the north of the main belt of tropical cyclones which form in the Timor sea, mostly between January and March and generally move to the south west Between 1975 and 1992 only five passed close to it compared with ten which passed within 10 of Rowley Shoals. Reef morphology indicates that the prevailing swell is from the south rather than from the west or south west as at Rowley Shoals and Scou Reef. The mean spring and neap tidal ranges are 4.7 m and 2.8 m respectively. (Tidal predictions for Ashmore Reef were supplied by the Tidal Laboratory of the Flinders Institute for Atmospheric and Marine Sciences, copyright reserved). Because of the large breaks in the reef there is no impounding of water within the lagoons at Ashmore Reef as occurs at the Rowley Shoals (Berry and Marsh 1986). No details of currents prevailing around Ashmore Reef are available but evidence of large scale transport from the Pacific Ocean through the Indonesian Archipelago into the Indian

3 Physical environment ASHMORE REEF

N

... ~ (J/ 12\>1 I ...... ,-.-. ' ...... • ...... 4...... -......

~REEF

III INTERTIDAL SAND FLATS

o, 5, 10km, [J] SHALLOW LAGOON

Flgure 2 Ashmore Reefdrawn from a LANDSAT image, showing localities ofsampling stations.

Ocean is provided by Wyrtki (1961), Godfrey and Golding (1981), Godfrey and Ridgeway (1984,1985) and Fine (1985). On the basis of examination of temperature charts from 1984-1986 derived from satellite imagery, the mean weekly sea surface temperature at Ashmore Reef was found to range from approximately 30°C from January to March to approximately 24°C in July and August

Reef Morphology Ashmore Reef is a shelf-edge atoll similar in shape and general morphology to the other atolls of the northwest, particularly the Rowley Shoals but also Scott and Seringapatarn Reefs (Berry and Marsh 1986). It differs from these in being orientated east-west instead of north­ south. It also occurs on a platform with an extensive shoal area less than 50 m deep and 12 km wide to its east instead dropping off into deep water on all sides; the 200 m contour lies close to its southern and western sides but the shallow platform on the north and east sides is part of the Sahul Shelf which is generally less than 100 m deep. In addition it has the most extensive areas of sand habitat ofall these atolls. According to Woodroffe (1984) the irregular outline of the reef crest of Ashmore Reef probably reflects the configuration of the underlying Tertiary basement encountered at a depth of 272 m in a drillhole on the reef (Anon. 1968).

4 P.F. Berry The reef (see Figure 2) is approximately 26 km long and 14 km wide (150 sq km). The windward (southern) reef margin reaches a maximum width of approx. 6 km, is unbroken and is backed by extensive sandflats. The leaward (northern) margin is narrow (approx. 1.4 km maximum), and broken by several broad passages which lead into two extensive shallow lagoon basins. There are three low (2.5 m) vegetated supratidal cays: West Island (approximately 1400 x 500 m, 33 ha), Middle Island (approximately 1200 x 400 m, 13 ha) and East Island (approx. 800 x 600 m; 16 ha). Woodroffe (1984) gives an account of the distribution of outcrops of beachrock and adjacent cemented sands and phosphatized boulders occurring on the islands, as well as describing their sedimentary characteristics. He describes the sediments as skeletal carbonate sands, principally composed of fragments of foraminifera tests and mollusc shells. Coral fragments are present but mainly in the fine sands. The outer reef slope, where examined off the southern (windward) margin, is gently inclined (approx. 5°) forming a shelf about 150 m wide. There is evidence of strong surge with surge channels developing into spur and groove formations. Soft corals predominate; hard corals are sparsely scattered or in small isolated patches. On the northern (leaward) margin the outerreef slope is very steep and in those places examined drops off sheer from 3 to 20 m before sloping away at about a 35° angle. The precipitous walls are covered in prolific hard coral growth. The reef front consists of hard pavement consolidated by encrusting algae. The crestal area is poorly defined with Heliopora, Porites and robust Acropora growing on poorly consolidated rubble. On the southern reef front some isolated boulder accumulations occur. No residual coral stacks as occur at Rowley Shoals were examined, but what appeared to be some were observed from the vessel on the north-eastern reef crestal area. The southern reef flat is composed of loosely consolidated rubble and dead coral slabs extending northwards from a poorly defmed crestal area and becoming progressively aligned into longitudinal striations or drainage depression. Some such depressions are deep, retain water and corals grow on rubble concentrations on their floors. The rubble accumulations become progressively larger, with more large coral slabs and interspersed sand in which sparse seagrass (Thalassia) growth occurs. The reef flat eventually gives way to extensive areas of sand flat with sparse Thalassia growth, scattered dead coral slabs and encrusting algal turf. The northern reef flat is similar to the southern one but narrower and with very little or no sandflat behind it. To the south ofMiddle Island are huge expanses ofsand flat devoid ofalgal turfor seagrass. In contrast the sand flats to the north of the island support a prolific growth of algal turf and some seagrass and are very much richer in benthic fauna. The extensive lagoon has two deep basins, the maximum depth recorded by echosounder was 46 m. Rising from the sandy bottom are numerous patch reefs of varying magnitude, some reaching the surface at low spring tides. Cartier Island is an oval shaped platform reef approximately 4.5 km x 2.3 km with a single, supratidal, unvegetated sand cay (see Figure 3). Like Ashmore Reef, it is orientated with the long axis east-west The southern outer reef slope is wide, gently sloping and surge washed with little hard coral growth, whereas on the northern side itdrops offsteeply, to 20 m and soft coral growth is prolific. At the base of the dropoff is a sandy ledge about 45 m wide. The northern reef was similar to that at Ashmore Reef with a crest of consolidated pavement, developing into a reef flat about 500 m. wide, composed of rather unconsolidated coral rubble and dead coral slabs with some living coral growth and sparse Thalassia scattered between them. This extends right up to the adjacent islet. The southern reef flat was not examined but in contrast to the northern reefflat it grades into a very wide expanse ofsand flat which, where

5 Physical environment

N CARTIER ISLAND IICAY t o BEACH ROCK

Iili11mI SAND FLATS liliWJ (dry at low tide) n SAND FLATS Ii.J (submerged)

[ill DEEP POOLS

o 1 2km ~REEF I I I

Figure 3 Carder Island drawn from a LANDSAT image, showing localities ofsampling stations. examined behind the islet, is bare and biologically depauperate. There is an extensive outcrop of beachrock on the south of the islet. There is no lagoon on Cartier Island but off the north­ eastern corner of the sand cay there is a depression in the reef flat in which Indonesian prahus anchor.

Notes On Exploited Species At least 25 Indonesian prahus were present at Ashmore Reef for the duration'of the expedition and three were present at Cartier Island when it was visited. Traditional fishing observed was by diving from dugout canoes using only wooden goggles (trochus, beche-de­ mer, rock lobsters and clams), reef walking at low tide (clams, 'collector-type' shells e.g. tiger cowries) line fishing, usually by trolling from dugouts, and spearfishing using home-made spearguns (rock lobsters and reef fishes). Although Ashmore Reef has an exceptionally diverse holothurian fauna (47 species compared with 25 for Scott Reef and 21 for Rowley Shoals (see Marsh, Part 6) preferred beche­ de-mer species were rare at Ashmore Reef and Cartier Island despite extensive areas of apparently suitable habitat sampled. A total of only four Holothuria (Microthele) nobilis, one Actinopygya echinites and two Actinopyga mauritiana was recorded by Marsh (see Part 6) at Ashmore Reef. She recorded an additional one specimen of each of these species at Cartier Island. No Thelenota ananas were seen except for eight specimens collected by Indonesians (a days catch by four people). The small black holothurian, Holothuria atra, abundant on most coral reefs, was only moderately common at Ashmore Reef. It is not known whether this species is fished by the Indonesians. It is usually regarded as oflow commercial value. The very low numbers of commercial species of beche-de-mer seen suggests that fishing

6 P.F. Berry pressure on the resource is intense at Ashmore Reef and Cartier Island. Observations at Scott Reef (Marsh 1984) indicated that H. (Microthele) nobilis was fished almost exclusively by the Indonesians. All the commercial species were uncommon at Scott Reef. At Clerke Reef (Rowley Shoals) in 1982 Thelenota ananas was abundant in some back reef areas and A. mauritiana was abundant on the outer reef flats. H. (Microthele) nobilis, although never common, was found at a number ofsites (Marsh 1984). Five species of Tridacnidae were recorded at Ashmore Reef and Cartier Island (see Wells, Part 4). Of the potential food species, Hippopus hippopus, the species generally least favoured by Indonesians, predominated. There are no quantitative data comparing clam population density or composition at Ashmore Reef, Scott/Seringapatarn Reefs and the Rowley Shoals. However, it was evident that clam numbers were much lower at Ashmore Reef and Scott/ Seringapatam Reefs than at Rowley Shoals where Tridacna squamosa formed a conspicuously higher proportion of the clam population (Wells Part 4). One quantitative observation of clam exploitation was made at the southern end of the station 14 transect. Two prahus were grounded on the reef flat at low tide and their crews (at least 15 men were involved) had covered a large area of reef flat gathering clams. This was apparent because they had placed the empty clam shells on exposed elevated coral slabs, apparently to help to keep track of where they had already searched. Being late afternoon, the sun caught the shiny white interiors of the clams along an estimated 2 km of outer reef flat A count of 184 shells (almost all H. hippopus) was made within a 300 m radius of the observer. On the basis of this count it is estimated by extrapolation that at least 1300 clams had been harvested at this single low tide along about 2 km of reef flat The estimated density of exploited clams was 6.5 ha. Compared with Rowley Shoals, Tectus niloticus was extremely scarce at Ashmore Reef (only four individuals were recorded) (Wells Part 4). Tiger cowries were also scarce in comparison with Rowley Shoals. On numerous occasions Indonesians approached expedition members seeking to barter or sell 'collector-type' shells such as tritons, helmet shells, cones and tiger cowries. While some exploitation of these shells may be traditional, it is likely that the modem tourist market in Indonesia may have increased the incentive to collect this type of shell. Turtles (Chelonia mydas) are captured at Ashmore Reef by Indonesians, probably while laying eggs and kept alive, tethered on long ropes to stakes anchored in sand flats (Sarti 1985). Only two turtles (Chelonia mydas) were seen at Ashmore Reef, a low number considering the suitability of habitat There were no signs of recent nesting at Middle or West Islands. Three recent nests were visible on Cartier Island. There was no evidence of exploitation as documented by Sarti. Ashmore Reef, like Scott Reef, was remarkable in having almost no large reef fish. In contrast, large and extremely large reef fish abound at Rowley Shoals. While long-term heavier fishing pressure at Ashmore and Scott Reefs is a possible explanation for this, there is also a possible biological explanation which implicates sea-snakes (which are absent on Rowley Shoals but extremely abundant at Ashmore and Scott Reefs) in driving away large reef fish (Berry 1984). In conclusion, observations suggest that the present composition and abundance of species exploited by Indonesian fishermen of Ashmore Reef and Cartier Island is almost certainly affected by fishing effort. This is highest at Ashmore Reef and progressively lower at Scott Reef and Rowley Shoals which are more inaccessible to these fishermen.

7 Physical enviromnent

Table 1. Western Australian Museum Sampling stations at Ashmore Reefand Carrier Island, 1986 (see Figures 2 and 3).

Station Date Locality Habitat Depth (m) Method 1 11.9 S.ofWesternlagoon Innerreefflat; coarse calcareous sand; low band ofcoral rubble. Intertidal Walking 2 11.9 E. ofWest Island Lagoon; isolated patchreef. 2-10 SCUBA 3 12.9 Transect of Mid-outer reefflat; coarse S.W. reefflat sand grading into rubble and consolidated calcareous pavement on reeffront. 0-0.5 Walking 4 12.9 S.W. outerreefslope Reefslope 35° slope, wave- washed pavement with sparse hard coral cover. 10-20 SCUBA 5 13.9 Entrance to western Isolated reefrising from lagoon basin sand bottom. Wave-washed butprolific hard coral and Alcyonacea growth. 10-20 SCUBA 6 13.9 Adjacent to entrance Backreefadjacent to lagoon ofeastern lagoon entrance. Prolific hard coral basin growth dominated by Acropora spp. 1-3 Snorkelling 7 14.9 Entrance ofeastern Lagoon entrance; flat sand! lagoon basin rubble with isolated rich 6 SCUBA coral patches. 8 14.9 NE outer reefslope Reefslope; near vertical dropoff to ledge at 20 m, hard cornl and gorgonian growth. 2-22 SCUBA 9 14.9 N.B. backreef, False Back reef; rubble and dead Passage coral slabs with little live hard cornl. 3(1-2) Snorkelling 10 15.9 S.E. comer ofreef Protected indentation in reef; longitudinally orientated hard cornl ridges mainly (Acropora) interspersed with rubble. 12 SCUBA 11 15.9 N.E. corner ofreef Reefslope near vertical drop- offto ledge at 30 m, prolific hard coral, alcyonacean and gorgonian growth. 30 SCUBA 12 15.9 Northern sand cay Sand cayand surrounding sandflats. Intertidal Walking 13 16.9 N. point ofreef Reefslope near vertical drop-off to ledge at 17 m. Dropoffprobably continuous along N reefslope (see stations 5, 8 and 15). 17 SCUBA 14 16.9 Middle Island Reefflat; sand with algal turf, transect sparse seagrass and biologically rich N ofMiddle Island, bare sand biologically depauperate S ofit. Intertidal Walking 15 17.9 W. ofE. Lagoon Reefslope near vertical drop- entrance offto to ledge at 18 m (see stations 5, 8 and 13). 18 SCUBA

8 P.P. Berry

Table 1. (cont.)

Station Date Locality Habitat Depth (m) Method 16 17.9 & Transect from N. of Reefflat; best seagrass beds 18.9 W. lagoon basin encountered (Thalassodendron to N. reeffront and Thalassia)on sand and rubble. Reefwell concreted with coraline algae. Heliopora conspicuous. futertidal Walking 17 18.9 Isolated reefc. 4 Wave washed reefwith scour km N.E. ofW. lagoon channels; little hard coral in Entrance isolated patches. 17 SCUBA 18 19.9 S.W.ofMiddle "Blue hole"; shallow basin with islandsteep coral lined sides. Ex- tensive staghornAcropora thickets. 7 SCUBA 19 19.9 S.E.ofW.lagoon Lagoon; spectacular patch reef basinrising from sand to surface. Prolific hard coral. 20 SCUBA 20 19.9 E. ofFalse lagoon Reefflat; back reefas in 6, entranceflat very unconsolidated dead Acropora patches with seagrass interspersed. Consolidated algal reefcrest with Heliopora conspicuous. 3- futertidal Walking Sampling stations at Cartier islet, 1986

Station Date Locality Habitat Depth (m) Method 1 20.9 Centre ofnorthern Outer reefslope; steep slope margin with good hard coral and alcyonacean growth dropping to broad (50 m) sandy ledge with isolated patches. 20 SCUBA 2 20.9 Transect ofisland Reefflat; N. ofisland uncon­ solidated rubble and dead slabs interspersed with seagrass. S. ofisland bare, biologically21.9 depauperate sand. futertidal Walking 3 21.9 S.W.ofreef Reeffront; gently sloping wave­ washed rubble bottom, scattered hard coral patches. 20 SCUBA 4 21.9 E. ofreef Reeffront; as for 3. 10 SCUBA

Habitats Ashmore Reef Carlier Island Totals - Reef flat 4 1 Sand flat 2 o Lagoon 6 o Outer reefslope & deep reef 8 3 - .4.

9 Physical enviromnent

Table 2. Northern Territory Museum Sampling stations at Ashmore Reef, 1986-1987

Station Date Locality Habitat Depth (m) Method

1 18 dates between E.ofWestIsland Reefflat Intertidal Walking 21.7.86 & 25.9.87 2 19 dates between E.ofWestIsland Lagoon bomrnies 1-18 SCUBA 22.7.86 & 20.9.87 3 14 dates between N. ofWest Island Reefflat Intertidal Walking 24.7.86 & 26.9.87 4 29.7.86,21.4.87 W.ofWestIsland Reefflat Intertidal Walking 13.9.87 5 26.7.86 W. side ofW. passage Reefslope 3-12 SCUBA 27.7.86 W. side ofW. passage Reefslope 9-21 6 28.7.86 W. side Ashmore Reef Outer reefslope 13-18 SCUBA 7 12 dates between E. side ofW. passage Reefslope 4-21 SCUBA 15.4.87 & 26.9.87 8 4 dates between N. ofWest Island Reefcrest 0-0.5 Walking 27.7.86 & 24.9.87 9 18.4.87 E.ofEastislet Outer reefslope 10-18 SCUBA 10 18.4.87 S. ofMiddle islet Outer reefslope 3-8 SCUBA 11 26.9.87 S. ofWest Island Outer reefflat Intertidal Walking 12 24.9.87 N. ofN.W. Ashmore Deep reef 18-20 SCUBA 13 14.9.87 W. side ofMiddle islet Reefflat Snorkelling 14 16.9.87 E. side ofMiddle Reefedge 3-4 SCUBA passage 15 17.9.87 Between West and Sand flats 3 Beam trawl Middle islands (at high and tide) rotenone 16 19.9.87 N. ofWest Island Sand and seagrass flats 2 Beam trawl 17 20.9.87 N. ofEast islet Reeffront 8-12 SCUBA 18 22.9.87 W.ofEastpassage Reeffront 12-14 SCUBA entrance 19 15.9.87 W. side ofWest Beach rock on Island shore Intertidal Walking 20 21.9.87 N.W. corner of Rubble bank 0.2 Walking West Island

Habitats Totals - Reef flat 6 Intertidal rock 2 Sand flats 2 Lagoon 2 Outerreefslope and deep reef 8

20

10 P.F. Berry Acknowledgements ~e fieldwork at Ashmore Reef and earlier Island was supported by a Marine Science and Technologies grant. Permission to collect fauna was granted by the Director of the Australian National Parks and Wildlife Service. Dr Terry Knight, honorary medical officer, and Peter and Glenys Sartori, operators of the Piscean are warmly thanked for their contributions to the expedition. Meljssa Hewitt drafted the figures.

References Anon. '(1968). B.9.C. ofAustralia Ltd. Ashmore Reef No.!. Log ofdrill hole..Open file. Anon. Cl ~79). List of marine invertebrates collected at Seringapatam and Ashmore Reefs by the Far Eastern Scientific'Centre Academy of Sciences U.S.S.R. Expedition on the R/V Professor Bogorov, October 1978. (Unpubl., Report, Dept ofForeign Affairs, Canberra). Berry, P.P. (Eel.) (1986). Faunal surveys of the Row1ey Shoals, Scott Reef and Seringapatam Reef. Rec. West. Aust. Mus. (25.): 1-106. Berry, P.F: ana Marsh, L.M. (1986). Part I. History ofinvestigation and descriptions ofthephysical environment. In: Faunal surveys of the Rowley Shoals, Scott Reef and Seringapatam Reef. Rec. West. 4ust. Mus. (25): 1- 106. . Dunson; W.A. et al. (1975). The Biology ofSea Snakes (ed. W.A. Dunson). University ParkPress, Baltimore. Edgerley, D.W. (1974). Fossil reefs of the Sahul Shelf, Timor Sea Prof:. Second bit. Coral ReefSymp. 2: 627- 637. . Fine, R.A. (1985)." Direct evidence using tritium data for throughflow from the Pacific into the Indian Ocean. Nature 315: .478-480. ' Forbes, M. (1982). Australian National Parks and Wildlife Service report on a visit to the Ashmore Reef, Dec. 1982 (unpubl.). Godfrey, J.S. and Golding T.J. (1981). The Sverdrnp relation in the hidiailOcean, and the effect ofPacifi.c-Indian Ocean throughflow' on Indian Ocean circulation and on the East Australian Current. J. Phys. Oceanogr. 11: 771-779. . Godfrey, J.S. and'Ridgeway K.R. (1984). Seasonal behaviour and possible mechanisms of the Leeuwin Current, Western-AUstralia Trop. Ocean. -Atmos. Newslett. 26: 16-17. : Godfrey,·J.S. and Ridgeway K.R. (1985). The large-scale environment ofthe poleward-flowmg Leeuwin Current, Western Australia: longshore steric height gradients, wind stresses, and geostrophic flow. J. Phys. Oceanogr. 15(5): 481-495. " . Hicks, J. 09.83). Australian National Parks and Wildlife Service report on Ashmore Reef National Nature Reserve October 1983 investigations (unpubl.). MacKnight, C.C. (1976). The voyage to Marege: Macassan Trepangers in northern Australia. Careton, Vie. Sarti, N. (1983): Report to Chief Fisheries Officer on a visit to Ashmore Reef, February, 1.983. W.A. Dept of Fisheries and WiJ,dlife (unpubl.). ' '. Sarti, N. (1-985). Circular patterns in sand - Ashmore Reef. Report to ChiefFisheries Officer (unpubl.). Serventy, D.L..(l952). The.bird islands ofthe Sahul Shelf. Emu 52: 33-59'. Woodroffe, C.D. '(1984). The geomorphology ofAshmore Reef and Cartier Island. Preliminary report on a visit on 15-17 June i984 (unpubl.). Wyrtki, K. (1961). Physical oceanography ofthe southeast Asian waters. NAGA Rep. 2. University of California Press.

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