Ian Miller 1 ABSTRACT

Transcription

1 Proceedngs 9 th Internatonal Coral Reef Symposum, Bal, Indonesa October 2000, Vol. 2. Hstorcal patterns and current trends n the broadscale dstrbuton of crown-of-thorns starfsh n the northern and central sectons of the Great Barrer Reef Ian Mller 1 ABSTRACT The Great Barrer Reef (GBR) s experencng a thrd seres of crown-of-thorns starfsh (COTS) outbreaks. Current trends n the broadscale dstrbuton of COTS appear to follow the pattern of the last two seres of outbreaks recorded from 1966 to 1974 and 1979 to The frst outbreaks n ths current seres were observed n the Cooktown/Lzard Island sector n 1993 and COTS actvty n ths sector contnued to ncrease untl 1999, but has snce declned. COTS outbreaks were subsequently observed n the Carns sector n 1995 the Innsfal sector n 1997 and the Townsvlle sector n Snce then, COTS actvty n the Carns, Innsfal and Townsvlle sectors have contnued to ncrease. The current pattern of outbreaks s consstent wth the hypothess that COTS outbreaks have ther geness n the Cooktown/Lzard Island sector (north of 16 S) and then cascade southward down through the GBR reef mosac n subsequent years and generatons. Ths pattern of outbreaks s also qualtatvely consstent wth numercal models of hydrodynamcs and larval dspersal that have prevously been used to smulate the large-scale populaton dynamcs of COTS. Implcatons for reefs currently affected and those recoverng from prevous COTS outbreaks are dscussed. Keywords Crown-of-thorns, Coral, Dstrbuton, Trends, Great Barrer Reef Introducton Over the last forty years Acanthaster planc (the crown-of-thorns starfsh or COTS) has caused sgnfcant coral mortalty throughout the tropcal Indo-Pacfc. Two seres of outbreaks on Australa s Great Barrer Reef (GBR) between and (Moran et al. 1992) have posed a consderable threat to reef productvty and reef based ndustres. More recently a thrd seres of outbreaks has been recorded from the GBR (Sweatman et al. 1998). Hstorcally the frst confrmed COTS outbreak on the GBR was at Green Island n 1962 (Barnes 1966). Between 1966 and 1974 a varety of surveys were conducted at varous tmes and locatons to determne the extent of COTS actvty on the GBR (Moran 1986). From these survey s t became apparent that outbreaks occurred further south wth tme (Talbot and Talbot 1971, Pearson 1972, Endean 1974). Kenchngton (1977) suggested that prmary outbreaks responsble for the observed COTS actvty had occurred north of Green Island n the 1950 s. Prmary outbreaks produced a cloud of larvae that traveled south wth water currents seedng reefs downstream. In turn secondary outbreaks produced more larvae that travel further south and outbreaks appeared to move down the GBR wth tme. Kenchngton (1977) based hs hypothess on sze frequency data. Unfortunately there were a number of problems wth ths model: alternatve nterpretatons of the sze frequency data; lack of evdence for prmary outbreaks; lack of consstency n the southward trend (.e. surveys themselves tended to be conducted further south wth tme); and a lack of nformaton about water crculaton n the matrx of reefs comprsng the GBR (Moran 1986). By 1977, the threat of COTS to the GBR was consdered to have faded (Kenchngton and Pearson 1982). No outbreaks were recorded after 1977 for almost two years (due n part to a lack of major scentfc surveys durng ths perod (Moran 1986)). In late 1979 another large populaton was observed on Green Island (Endean 1982). By the end of 1984, 24 md-shelf reefs n the Carns/Innsfal sectors of the GBR had extensve areas of dead coral attrbuted to COTS predatory actvty (Great Barrer Reef Marne Park Authorty 1985). By the mddle of 1985, the southern and northern lmts of ths second seres of outbreaks were to be found at reefs near Townsvlle and Lzard Island respectvely (Moran 1986). Broadscale surveys of the entre reef system usng manta tow were mplemented by the Australan Insttute of Marne Scence (AIMS) n AIMS surveys addressed methodologcal dfferences common n prevous surveys (Moran et al. 1988). For the frst tme the entre expanse of the GBR was sampled systematcally n a sngle year. Reefs have been sampled annually usng the manta tow technque along the length of the GBR snce ths tme (Sweatman et al. 2000). AIMS surveys ndcated that by the second seres of outbreaks had almost run ts course (Baker et al. 1992). The frst to revst the Kenchngton southern drft hypothess were Rechelt et al. (1990). Ther results ndcated a strong southward drft of COTS actvty consstent wth the speed and drecton of average summer currents on the GBR. They predcted that f outbreaks are coupled to coral recovery patterns then the next perod of hgh COTS actvty n the central secton of the GBR would be expected n the late 1990 s. However at that tme they could not demonstrate the concept of a dscrete seed area to ntate the wave. Further analyss by Moran et al. (1992) detected a strong southern drft for both prevous seres of outbreaks as well as a weak northern drft n the second seres of outbreaks and suggested a lkely epcenter for outbreaks on the GBR of around 16 o S. Extensve modellng of water currents (e.g. 1 Australan Insttute of Marne Scence, PMB #3 Townsvlle MC, Qld, Australa 4810

2 Dght et al. 1990a, James and Scandol 1992), passve larval transport wthn the lagoon of the GBR (e.g. Dght et al. 1990b, Scandol and James 1992) and genetc structure of COTS populatons (Benze 1992) provded further support for the hypothess. However Van der Laan and Hogeweg (1992) dd ndcate that the observed waves of COTS outbreaks on the GBR dd not necessarly mply that there was a seed area n the north. More recent analyss of the hstorcal data has provded an alternate vew. Bradbury and Seymour (1997) suggested that n fact the travellng wave of outbreaks was becomng less dstnct wth tme and changng towards a more system wde pulse as the proporton of reefs avalable to host outbreaks declned through tme. Ths was nterpreted as an ndcaton that communty structure was beng damaged over tme and was perhaps a sgnal of the long-term declne on the GBR (Seymour and Bradbury 1999). Recent data obtaned from manta tow surveys of the GBR ndcate that there has been a marked ncrease n COTS actvty n the Northern (Carns) and Central sectons of the GBR over the last fve years (see Mller et al. 1997, Sweatman et al. 1998). A smlar pattern has also occurred n the Swan Reefs to the south. Factors affectng outbreaks n the Swan Sector have been largely unexplored. Though Benze (1992) hghlghted the strong genetc lnkages between COTS outbreaks n the southern GBR and those further north they are generally consdered as a separate ssue (Moran et al. 1992, Rechelt et al. 1990). Thus data from ths regon s not ncluded. Ths paper presents a prelmnary analyss of the AIMS manta tow survey data snce 1992 to determne; f the current seres of outbreaks confrms to Kenchngton s 1977 southern drft hypothess, how outbreaks affect regonal (.e. sectonal) coral cover, and mplcatons for reefs recoverng from prevous outbreaks to the south of those currently affected. Methods A sute of reefs, n 11 cross shelf sectors has been surveyed annually snce 1985 usng manta tow. Before 1992 reefs were sampled haphazardly wth logstcal effcency determnng numbers of reefs sampled wthn each of the sectors. In 1992 manta tow surveys were ncorporated nto the AIMS long-term montorng program (LTMP) wth a systematc samplng protocol (Sweatman et al. 2000). Ths paper presents results from four of the eleven cross-shelf sectors n the Northern and Central Sectons of the GBR (Cooktown/Lzard Island, Carns, Innsfal and Townsvlle)(Fg. 1). Reefs n these sectors had been repeatedly surveyed well before the frst outbreaks n the current seres were detected. The samplng program ncludes key and cycle reefs (Table 1). Key reefs are sampled annually, whle cycle reefs are surveyed every three years. Small numbers of reefs have been dropped from the survey n some years due to poor weather. Fg. 1 Map of the northern and central Great Barrer Reef showng locaton of reef sectors. Table 1. Number of key and cycle reefs n four cross-shelf sectors of the GBR that are targeted by the AIMS LTMP on an annual bass. Reef sector Key Cycle Total Cooktown/ Lzard 30 9 Is (10/year) 19 Carns (7/year) 18 Innsfal 2 12 (4/year) 6 Townsvlle 10 6 (2/year) 12 At each survey reef a snorkeler s towed behnd a small boat at 3-5 km/h by holdng on to a manta board. The boat drver tows the observer parallel to the reef crest and close enough for the observer to see as much of the reef slope as possble. Two boats tow observers n opposte drectons from a desgnated startng pont, around the reef permeter, untl they meet. As the observers proceed along the reef edge they vsually scan the benthos. At two-mnute ntervals the drver stops the boat and the observers record the data from the prevous tow on waterproof paper attached to the manta board. Data conssts of COTS counts and estmates of lve coral, dead coral and soft coral. Ths process contnues untl the entre reef permeter s surveyed ( Bass and Mller 1996). To defne survey reefs wth respect to COTS actvty AIMS classfy reefs accordng to ther outbreak status. Defntons of outbreaks are strongly related to the type of survey technque used to count COTS (Moran 1986). In prncple Actve Outbreaks occur when starfsh denstes reach levels where loss of coral tssue through starfsh

3 feedng s estmated to be faster than the growth of the coral. Hstorcally coral cover, the number of COTS per reef and the average number of COTS per tow have been used to make the assessment (Fernandes 1991, Moran and De ath 1992). For AIMS broadscale survey the defnton of an Outbreakng COTS populaton has evolved over the tme. Intally, reefs wth actve outbreaks were those where >40 COTS were recorded over the whole reef and >30% of coral was dead. Examnaton of manta tow data from reefs of all categores found that 90% of reefs wth actve outbreaks by these crtera supported >1500 COTS km -2 (Moran and De ath 1992). Ths s approxmately 0.22 COTS per two-mnute tow. Ths fgure has been used to denote the mnmum crtera for Outbreakng status. For each survey, reef-wde percent cover of lve coral was calculated by addng the md-pont of the range of each recorded cover category and dvdng them by the number of tows for that reef. Smlarly mean counts of COTS (COTS/tow) were also calculated for each reef. Lnear models were used to ft smple (quadratc) curves to the sequence of observatons of mean coral cover (reefwde coral cover) and mean numbers of COTS per tow from each reef for the prevous sx years (after Sweatman et al. 2000). The ftted values from these curves for ndvdual reefs were then used to estmate the overall sxyear trend and the current (last survey year) trend for each sector. Sector trends were obtaned n the followng fashon: (1) For each reef the followng quadratc model was ft: y = β + β x + β x 2 + ε : Where y represents the average coral cover or the transformed COTS count n( mean COTS count + 1) l on a gven reef for year, β o represents the average response at year Z, β 1 represents the slope at year Z, β 2 represents the curvature of the trend, x = survey number - Z, and ε represents the error. (2) For each reef, the response for each year (ncludng the years where some observatons are mssng) was estmated usng the model presented n (1). (3) For each sector, the estmate of the average response was obtaned by averagng the predcted response for each reef for each year (Table 2). Comparsons between relatve denstes of COTS through tme and between sectors are explored graphcally. In ths case the average number of COTS recorded from each sector n each year are compared snce 1990 (Fg. 2). To examne the relatonshp between new outbreaks and lattude the frst recorded outbreak on reefs surveyed snce 1990 were compared through tme. The dstrbuton of outbreaks for the perod 1993 to 2000 was modelled by regressng the decmal lattude of frst recorded outbreaks (N=42) wth month of survey. The lnear model was found to provde the best ft (Fg. 3) Results Outbreaks were frst detected n the Cooktown/Lzard Island sector n COTS denstes ncreased up untl 1997, peakng at 0.45 COTS/tow before a declne n Whle there was no average trend n coral cover, the recent declne n COTS has been mrrored by ncreasng reef-wde lve coral cover (Table 2). Table 2 Modellng results for COTS and reef-wde lve coral cover n four sectors of the GBR. The average slope ndcates average change over the last sx years. The current slope s the change due to surveys n the year 2000 compared to the sx year average. Sgnfcant result s (P<0.05) are marked wth an astersk. Sector Cooktown/ Lzard Island Type Averag e slope P-value Current slope P-value COTS <0.001 * Coral * Carns COTS * * Coral COTS * * Innsfal <0.001 Coral * * COTS * * Townsvlle <0.001 Coral * Fg. 2 Chart showng the average number of COTS counted per reef through tme (years) n four sectors of the Great Barrer Reef. In the Carns sector COTS populatons have shown a sgnfcant trend of ncrease snce Surveys n 2000 ndcate a contnued ncrease to a level of 0.37 COTS/tow (Fg. 2). Coral cover remaned generally unchanged. For the Innsfal sector the frst Outbreaks were recorded n There has been a sgnfcant ncrease n

4 COTS actvty snce ths tme (Table 2). The large number of COTS recorded n 2000 (currently 3.07 COTS/tow) drves the sx year trend. Hgh number of COTS n recent years has lead to a sgnfcant decrease n reef-wde coral cover n both the long-term (sx year trend) and short term (2000). The frst outbreaks were recorded n the Townsvlle sector n The large number of COTS seen n 2000 (currently 3.49 COTS/tow) drves the sx year trend (Table 2). COTS contnue to ncrease and there has been a correspondng decrease n lve coral cover. The modellng results are reflected n Fg. 2. Pror to the current seres of outbreaks resdual COTS populatons were present n the Townsvlle sector. These subsequently declned. COTS bult up over a number of years n the Cooktown/Lzard Island sector followed by the Carns sector. In the Innsfal and Townsvlle sectors the buld up was sudden wth COTS numbers ncreasng sharply n Average COTS counts for both these sectors (n 2000) are nearly an order of magntude larger than n ether the Carns or Cooktown/Lzard Island sectors. The travellng wave of new outbreaks s seen clearly n Fg. 3. Results ndcate a sgnfcant lnear trend (P<0.001) of outbreaks movng progressvely southward wth tme. The southern drft orgnated n the Cooktown/ Lzard Island sector at 14.7 S. Outbreaks moved southward at a relatvely constant rate averagng 43 km year -1. The rate of southern drft though ntally slower than that recorded durng the prevous two outbreaks stll compares favourably overall (Table 3). There s lttle ndcaton of a northern drft wth only one COTS outbreak recorded on reefs n the Prncess Charlotte Bay sector mmedately to the north of the Cooktown/Lzard Island sector between 1993 and Fg. 3 Scatter plot of lattude of reefs where outbreaks were frst detected compared to tme durng the perod 1992 to Sold lne ndcate the ftted regresson lne together wth 95% confdence ntervals. Table 3 Estmated speed of southward movement (degrees of lattude year -1 ) of the centre of outbreaks for the perods , and the current seres of outbreaks (snce 1994). Perod Speed (year) Intal Fnal Average (1966) 0.731(1974) (1979) 0.205(1991) (1994) 0.390(2000) Dscusson Samplng by AIMS has provded the frst long-term record of the broadscale dstrbuton of COTS on the GBR. At the end of the second seres of outbreaks n 1991, surveys contnued wth a clearly defned methodology and samplng desgn. Crtcally, samplng contnued n the seed area at 16ºS. As a result, surveys were able to map changes n COTS densty pror to and durng, the thrd recorded seres of outbreaks. For the frst tme drect comparsons wth prevous outbreak hstory can be made. Results from surveys ndcate the current pattern of movement n locaton of COTS outbreaks n the Northern (Carns) and Central sectons of the GBR s broadly smlar to those recorded prevously. Ths s not surprsng. Regonal scale models based on the hydrodynamcs and dspersal of passve COTS larvae (Dght et al. 1990a, Dght et al. 1990b, James and Scandol 1992, Black et al. 1995) show a mechansm for the net southward movement and recrutment of COTS larvae n prevalng currents. The fact that Rechelt et al. (1990) predcted the current outbreaks on the central secton of the GBR and Bradbury and Seymour (1997) enttled ther paper Watng for COTS clearly ndcates that the current seres s not unexpected. The densty of COTS n the central secton of the GBR (Innsfal and Townsvlle sectors) s ncreasng. Ths has caused a declne n coral cover. A large mature female COTS can produce up to 60 mllon eggs per year (Kettle and Lucas 1987). Hgh fecundty combned wth the net southerly and onshore larval dspersal patterns found n the central secton of the GBR (Dght et al. 1990a, 1990b) makes t nevtable that reefs downstream wll soon experence elevated COTS populatons. Past hstory (Moran et al. 1992) and models of larval dspersal (James and Scandol 1992) would suggest that outbreaks are lkely

5 to extend nto the Cape Upstart and Whtsunday sectors n comng years. The majorty of reefs n these sectors that wll be affected are most lkely to be md-shelf reefs wth some nconsstences n the southward drft (.e. some reefs may experence large populatons before outbreaks are observed on reefs further to the north). Many reefs n these sectors are stll n a state of recovery from prevous outbreaks (Sweatman et al. 2000). The outbreaks n the northern secton (Cooktown/Lzard Island and Carns sectors) of the GBR present a somewhat dfferent pcture. COTS numbers have declned n the Cooktown/Lzard Island sector where no new outbreaks have been recorded snce The lack of sgnfcant change n average reef-wde coral cover over the perod of outbreaks ( ) s due to the declne n coral cover on affected reefs beng counteracted by ncreases n coral cover on unaffected reefs. New Actve Outbreaks were stll occurrng n the Carns sector n 2000 where COTS numbers contnue to rse. In nether case has the densty of COTS approached those currently on reefs n the Innsfal and Townsvlle sectors. The relatvely low denstes recorded from the Northern secton are apparently suffcent to ntate outbreaks downstream. The frst outbreaks n the current seres appeared at 14.7ºS n an area that marked the lmt of the northern drft durng the second seres of outbreaks. Contnued samplng of reefs n ths area clearly dentfed outbreaks that may be progentors of later outbreaks further to the south. However they are not necessarly themselves the prmary outbreaks for the current seres. Just what consttutes a prmary outbreak remans open to queston (Johnson 1992). Whle AIMS surveys dd detect outbreaks at the begnnng of the current seres, gven the relatvely small proporton of reefs sampled (approxmately 10%), the possblty remans that other earler outbreaks may have been mssed. Engelhardt et al. (1997) detected ncreases n COTS numbers on reefs near to and south of Lzard Island n 1994 and 1995 and an ncrease n recrutment throughout the regon 14-16ºS. They consdered ncreases n COTS numbers to have developed over a number of years through several recrutment events. Studes of the genetc structure of these populatons (Benze and Wakeford 1997) ndcated that COTS on several reefs n the regon act as one mxed populaton. The genetcs were consstent wth a small number of reefs contrbutng to the producton of a pool of recruts that buld up over tme untl they contrbute sgnfcantly to colonsaton of reefs downstream and gve rse to outbreaks on the central GBR. It was also lkely that the same source populaton has been responsble for the two prevous seres of outbreaks. Scandol and James (1992) hghlghted the mportance of the pattern of water currents n the Carns and Cooktown/Lzard Island sectors to the recrutment of COTS onto reefs n ths area. The lack of consstent drectonalty n water crculaton n the northern secton of the GBR and the dffuse nature of COTS recrutment would suggest that prmary outbreaks mght not necessarly occur dscretely on a partcular reef wthn the regon. Ths may explan why the northern drft observed by Moran et al. (1992) and modelled by Dght (1990b)was not observed durng the current seres. It s qute possble for the observed southern movng wave of outbreaks to be ntated further south than 16 o S (Van Der Laan and Hogeweg 1992). Though modelng does ndcate that f prmary outbreaks do occur to the south of Carns n the regon 17.5ºS to 19.5ºS, they are unlkely to ntate secondary outbreaks (James and Scandol 1992). Overall the smlartes between outbreak epsodes are strkng. The current seres s consstent wth the southern drft hypothess, wth a seed area behnd the Rbbon Reefs (14ºS to 16ºS). The events leadng to ntaton of outbreaks reman engmatc, and the effect to the longterm health of the GBR of repeated COTS outbreaks even more so. Seymour and Bradbury (1999) argue repeated outbreaks can result n a degradaton of reef communty structure because of the shortenng recovery tme between successve outbreaks (a vew put forward prevously by Cameron and Endean (1985), Done et al. (1988), Endean et al. (1988), Hatcher (1997). Lourey et al. (2000) rased the possblty that n terms of coral cover not all affected reefs on the GBR wll recover from sustaned outbreaks. Bradbury and Seymour (1997) suggested the dynamcs of outbreaks changng from a wave to a system wde pulse. However on a regonal level (northern and central sectons) the results presented here would tend not to support ths vew. In the Townsvlle and Innsfal sectors the large numbers of COTS and the resultng reducton n coral cover suggests that the capacty to sustan repeated outbreaks wll strongly depend on the length of tme t takes for coral to recover. Repeated outbreaks would be unlkely to occur on these reefs over a short tme frame smply due to lack of coral food for COTS. In contrast, for reefs n the northern secton the possblty exst for repeated outbreaks wthn the overall outbreak cycle, made possble by the relatvely low denstes of COTS havng a lesser mpact on coral cover and allowng COTS populatons to persst n the regon. COTS have been observed n the Cooktown/Lzard Island sector n every year of survey by AIMS. Ths combned wth nondrectonal water currents provdes the possblty for outbreaks to develop over a number of years through a seres of recrutment events. In fact as dscussed prevously ths s the mechansm that probably led to the ntaton of the current seres of outbreaks. Indeed Moran and Death (1992) noted three reefs n northern secton that, durng the second seres of outbreaks, experenced outbreaks 3-4 years after the other reefs n the regon. Gven the current frequency of outbreaks, combned wth a predcted ncrease n the sze and frequency of other mpacts on the GBR (such as cyclones and coral bleachng) through clmate change (Harmeln-Vven 1994, Hoegh-Guldberg 1999), COTS reman a threat to the long-term health of the GBR. Acknowledgements I would lke to thank the members of the AIMS feld team, partcularly, Debbe Bass, Alstar Cheal, Ben Ftzpatrck, Rachelle Nno, Kate Osborne,

6 Cathy Page and Angus Thompson for collectng the data. Thanks should also go to Greg Coleman for managng the data. I would also lke to thank Hugh Sweatman for comments on the manuscrpt and Dan Ryan and Steve Delean for statstcal advce. Ths s contrbuton number 1056 from AIMS. References Baker VJ, Bass DK, Chrste CA, Mller IR, Thompson AA (1992) Broadscale surveys of crown-of-thorns starfsh on the Great Barrer Reef 1991 to Australan Insttute of Marne Scence: Townsvlle: 132 pp. Barnes JH (1966) The crown-of-thorns starfsh as a destroyer of coral. Australan Natural Hstory 15: Bass DK, Mller IR (1996) Crown-of-thorns starfsh and coral surveys usng the manta tow and scuba search technques. Long-term Montorng of the Great Barrer Reef, Standard Operatonal Procedure No. 1, Australan Insttute of Marne Scence: Townsvlle: 38 Benze JAH (1992) revew of the genetcs, dspersal and recrutment of crown-of-thorns starfsh (Acanthaster planc). Aust J Mar Freshwater Res 43: Benze JAH, Wakeford M (1997) Genetc structure of crown-of-thorns starfsh (Acanthaster planc) on the Great Barrer Reef, Australa: Comparson of two sets of outbreak populatons occurrng ten years apart. Mar Bol 129(1): Black K, Moran P, Burrage D, De ath G (1995) Assocaton of low-frequency currents and crown-ofthorns starfsh outbreaks. Mar Ecol Prog Ser 125 (1-3): Bradbury R, Seymour R (1997) Watng for COTS Proc 8 th Int Coral Reef Symposum 2: Cameron AM, Endean R (1985) Do long-lved speces structure coral reef ecosystems? Proc. 5 th Int. Coral Reef Congress. 6: Kettle BT, Lucas JS (1987) Bometrc relatonshps between organ ndces, fecundty, oxygen consumpton and body sze n Acantaster planc (L) (Echnodermata;Asterodea). Bull Mar Scence 41: Dght IJ, James MK, Bode L (1990a) Modellng the larval dspersal of Acanthaster planc. I Large scale Hydrodynamcs Carns secton Great Barrer Reef Marne Park. Coral reefs 9: Dght IJ, James MK, Bode L (1990b) Modellng the larval dspersal of Acanthaster planc. II Patterns of reef connectvty Coral Reefs 9: Done TJ, Osborne K, Navn KF (1988) Recovery of corals post Acanthaster: progress and prospects. Proc 6 th Int Coral Reef Symp 2: Endean RE (1974) Acanthaster planc on the Great Barrer Reef. Proc 2 nd Int Coral Reef Symp 1: Endean R (1982). Crown-of-thorns starfsh on the Great Barrer Reef. Endeavour. (Oxford) 6: Endean R, Cameron AM, DeVanter LM (1988) Acanthaster planc predaton on massve corals: the myth of rapd recovery of devastated reefs. Proc. 6 th Int. Coral Reef Symp. 2: Engelhardt U, Mller I, Lassg B, Sweatman H, Bass D (1997) Crown-of-thorns starfsh (Acanthaster planc) populatons n the Great Barrer Reef World Hertage Area: Status report In: Wachenfeld D, Olver J, Davs K (eds) State of the GBR World Hertage Area Workshop. Proceedngs of a techncal workshop held n Townsvlle, Qld, November (GBRMPA Workshop Seres 23). Great Barrer Reef Marne Park Authorty, Townsvlle, Qld: Fernandes L (1991) Development of a more robust method for determnng the status of ndvdual reefs wth respect to outbreaks of crown-of-thorns starfsh Acanthaster planc. Report to GBRMPA, Townsvlle, Qld: 47 pp. Great Barrer Reef Marne Park Authorty (1985) Reeflectons 14:3-4 Harmeln-Vven ML (1994) The Effects of Storms and Cyclones on Coral Reefs: A Revew. Journal of Coastal Research Specal Issue No.12, Coastal Hazards : Hatcher (1997) Coral reef ecosystems: how much greater s the whole than the sum of the parts? Coral Reefs 16(5):77-91 Hoegh-Guldberg O (1999) Clmate change, coral bleachng and the future of the world s coral reefs. Mar Freshwat Res 50(8): James MK, Scandol JP (1992) Larval dspersal smulatons: correlaton wth crown-of-thorns starfsh outbreaks database. Aust J Freshwater Res 43: Johnson C (1992) Reproducton, Recrutment and Hydrodynamcs n the Crown-of-thorns Phenomenon on the Great Barrer Reef: Introducton and Synthess. Aust J Freshwater Res 43: Kenchngton RA (1977) Growth and recrutment of Acanthaster planc (L.) on the Great Barrer Reef. Bol Cons 11: Kenchngton RA, Pearson R (1982) Crown-of-thorns Starfsh on the Great Barrer Reef a stuaton report. Proc 4 th Coral Reef Symp 2: Lourey MJ, Ryan DJ, Mller IR (2000) Rates of declne and recovery of coral cover on reefs mpacted by, recoverng from and unaffected by crown-of-thorns starfsh Acanthaster planc: a regonal perspectve of the Great Barrer Reef. Mar Ecol Prog Ser 196: Mller IR, Bass D, Sweatman H (1997) Broadscale Surveys n Sweatman H (ed) Long-term montorng of the Great Barrer Reef. Status report Number 2: Australan Insttute of marne Scence, Townsvlle. Moran PJ (1986) The Acanthaster phenomenon. Oceanogr Mar Bol Ann Rev 24: Moran PJ, Bradbury RH, Rechelt RE (1988) Dstrbuton of recent outbreaks of crown-of-thorns starfsh (Acanthaster planc) along the Great Barrer Reef. Proc. 5 th. Int. Coral Reef Congress 5:321-6 Moran PJ, De ath G (1992) Estmates of the abundance of the Crown-of-Thorns starfsh Acanthaster planc n outbreakng and non-out breakng populatons on reefs

7 wthn the Great Barrer Reef. Marne Bology 113: Moran PJ, De ath G, Baker VJ, Bass DK, Chrste CA, Mller IR, Mller-Smth BA, Thompson AA (1992) pattern of Outbreaks of Crown-of-thorns Starfsh (Acanthaster planc L.) along the Great barrer Reef snce Aust J Freshwater.Res 43: Pearson RG (1972) Changes n the dstrbuton of Acanthaster planc populatons on the Great Barrer Reef. Nature 237: Rechelt RE, Bradbury RH, Moran PJ (1990) Dstrbuton of Acanthaster planc outbreaks on the Great barrer Reef between 1966 and Coral reefs 9: Scandol JP, James MK (1992) Hydrodynamcs and larval dspersal: A populaton model of Acanthaster planc on the Great Barrer Reef. Aust J Freshwater Res 43: Van der Laan JD, Hogeweg (1992) Waves of crown-of- Seymour RM, Bradbury RH (1999) Lengthenng reef recovery tmes from crown-of-thorns outbreaks sgnal systematc degradaton of the Great Barrer Reef. Mar Ecol Prog Ser 176:1-10 Sweatman H, Bass D, Cheal A, Coleman G, Mller I, Nno R, Osborne K, Ryan D, Thompson A, Tomkns P (1998) Long term montorng of the Great Barrer reef. Status report number 3. Australan Insttute of Marne Scence: Townsvlle: 303 pp. Sweatman H, Cheal A, Coleman G, Ftzpatrck B, Mller I, Nno R, Osborne K, Page C, Ryan D, Thompson A, Tomkns P (2000) Long term montorng of the Great Barrer reef. Status report number 4. Australan Insttute of Marne Scence: Townsvlle: 117 pp. Talbot FH, Talbot MS (1971) The Crown-of-thorns Starfsh (Acanthaster) and the Great Barrer Reef. Endeavour 30:38-42 thorns starfsh outbreaks. Where do they come from? Coral reefs 11: