Ecological survey on coral reefs of Simeuleu and Banyak Islands - Aceh 2007

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2 Ecological survey on coral reefs of Simeuleu and Banyak Islands - Aceh 27 Report no. REP/XIX/EXT/2/8/ENG Yudi Herdiana, Tasrif Kartawijaya, Rizya L. Ardiwijaya, Fakhrizal Setiawan, Rian Prasetia, Shinta T. Pardede, Stuart Campbell Wildlife Conservation Society Indonesia Marine Program Jl. Burangang 18 Bogor Ph: admin@wcsmarine-indonesia.org

3 Ecological survey on coral reefs of Simeuleu and Banyak Islands - Aceh 27 WCS Indonesia Marine Program. 28 Citation: Y. Herdiana, T. Kartawijaya, R.L. Ardiwijaya, F. Setiawan, R. Prasetia, S.T. Pardede, S. Campbell. 28. Technical Report - Ecological survey on coral reefs of Simeulue and Banyak Islands - Aceh 27. Wildlife Conservation Society - Indonesia Marine Program. Bogor, Indonesia. 16pp This report supported by:

4 ACKNOWLEDGEMENT The Wildlife Conservation Society Indonesia Marine Program would like to thanks to: 1. Fauna and Flora International regarding the support for the field survey. 2. Dr. Andrew H. Baird from the Australian Research Council Centre of Excellence for Coral Reef Studies (ARCCoERS) for great collaboration, data enrichment, and knowledge transfer. 3. Anthony A Toole for the great photos.

5 CONTENT 1. Introduction 1 2. Ecosystem Condition 2 OBSERVATION SITES 2 CORAL REEFS 3 A. Live coral coverage 3 B. Recruitment of hard coral 4 C. Genera diversity of hard coral 4 REEF FISH COMMUNITY 5 A. Species richness of reef fishes 5 B. Biomass and abundance of reef fishes 6 C. Composition of reef fish biomass and abundance 8 MACRO INVERTEBRATES 1 3. Threat and Damage Recommendations 15 References

6 FIGURES Figure 1. Survey locations in Simeulue Island and Banyak Islands, Aceh 2 Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Mean (±SE) live coral cover at 35 sites on Simuelue Island, Banyak Islands and the Sumatran coast. 3 Mean (±SE) of live coral cover based on management areas on Simuelue Island, Banyak Islands and the Sumatran coast. 3 Mean (±SE) number of coral recruits (no.m -2 ) at 35 sites on Simuelue Island, Banyak Islands and the Sumatran coast. 4 Mean (±SE) Simpson s diversity index of hard coral genera (Indeks Simpson s) at 35 sites on Simuelue Island, Banyak Islands and the Sumatran coast. 4 Family composition (left) and total number of species (right) of reef fishes, found at 35 survey sites. 5 Mean (±SE) biomass of reef fishes (kg ha -1 ) at 35 sites in Simuelue Island, Banyak Islands and the Sumatran coast. 6 Figure 8. Mean (±SE) biomass of reef fishes (kg ha -1 ) in each management area. 6 Figure 9. Mean (±SE) abundance of reef fishes (no ha -1 ) at 35 sites in Simuelue Island, Banyak Islands and the Sumatran coast. 7 Figure 1. Mean (±SE) abundance of reef fishes (no.ha -1 ) in each management area. 7 Figure 11a. Mean (±SE) biomass of 6 major reef fish families (kg ha -1 ) in each management area. 8 Figure 11b. Mean (±SE) biomass of reef fishes (kg ha -1 ) based on size class for each management area. 8 Figure 12a. Mean (±SE) abundance of 6 major reef fish families (no ha -1 ) in each management area. 9 Figure 12b. Mean (±SE) abundance of reef fishes (no ha -1 ) based on size classes in each management area. 9 Figure 13. Mean abundance (± SE) of giant clams (Tridacnidae) at 35 sites in Simuelue Island, Banyak Islands and Sumatra. 1 Figure 14. Species composition of clam (Tridacnidae) found at 35 sites in Simuelue Island, Banyak Islands and Sumatra. 1 Figure 15. Mean abundance (no ha -1 ± SE) of Acanthaster planci at 35 sites at Simuelue Island,

7 Banyak Islands and the Sumatra coast; the red line denotes the number at which an invasion has occured. 11 Figure 16. Mean abundance (± SE) of sea urchins (Echinoidea) at 35 sites at Simuelue Island, Banyak Islands and the Sumatra coast. 11 Figure 17. Species composition of sea urchin (Echinoidea) at 35 sites at Simuelue Island, Banyak Islands and the Sumatra coast. 11 Figure 18. Comparison between the mean (±SE) hard coral cover in shallow waters and uplifted reef of Site 8, Mata Nurung, Simuelue Island. 13 Figure 19. Comparison between the percentage cover of hard coral genera in shallow waters and uplifted reef at Site 8, Mata Nurung, Simuelue Island. 13

8 The Wildlife Conservation Society Indonesia Marine Program has been working in Aceh since February 25. WCS has collaborated with James Cook University, the Fisheries Diving Club Bogor Agricultural University and Syiah Kuala University in Banda Aceh in assessing the impact of the 24 Sumatran-Andaman tsunami on the coral reef ecosystems of northern Aceh region (Weh Island and Aceh Islands). In addition to the tsunami, a series of earthquakes also impacted the northern and south-western island regions of Aceh. The earthquake on March 28, 25 and the following smaller ones caused tremendous damage to the coral reefs on Simeulue Island and Nias Islands, a group of islands located off the south-west coast of Sumatra. In February 27, WCS conducted a rapid ecological survey of the coral reefs of Simeulue and Banyak Islands, covering 35 sites along the 6 km coastline of west Aceh. The survey was conducted in collaboration with the Australian Research Council Centre of Excellence for Coral Reef Studies (ARCCoERS) and supported by the Flora and Fauna International (FFI). The objectives of the survey were to assess the impact of Nias earthquake on the surrounding coastal region; to examine the diversity and abundance of marine resources on coral reef ecosystems; and to study socio-economic factors and resource utilization at the local community level that influence marine resource use. All results and information collected in this survey will be used to support local strategic plans for coral reef conservation in the Aceh region. The earthquake in March 25 had its epicenter in the Banyak Islands and instigated the uplift of islands of Simeulue by metres from mean sea surface level. The coral reefs fringing approximately 3 km of the Simeulue coastline were up-lifted causing massive mortality to the coral reef ecosystem. In some locations the up-lifted reefs were still intact showing intact corallite structures making it possible for the corals to be identified to genus and sometimes species level. The damage not only caused mass mortality but also changed the Simeulue coral reef community structure. A number of coral species at particular sites that were uplifted could not be found in live communities and previously dominant species have been replaced by other species. During the survey, we recorded an outbreak of the Crown-of-thorn Starfish (Acanthaster planci) at several sites in the Banyak Islands. This phenomenon was responsible for causing 9% of the coral reef mortality recorded at these sites. The coral reefs of Simeulue and Banyak Islands are located south-west on the Province of Nanggroe Aceh Darussalam in the East Indian Ocean. Overall we characterized the condition of the reefs in this region as good condition, although some reefs showed signs of severe disturbance either from previous blast fishing, overfishing and crown of throrn predation. The survey recorded 38 species of shallow hard corals and 36 species of coral reef fishes. The cover of hard coral varied among the 35 survey sites according to management type. Based on the parameters we measured to assess coral reef condition (reef substrate cover, fish abundance and biomass, and macroinvertebrate abundance), the reef condition of the Community Marine Protected Area (Kawasan Konservasi Laut Daerah-CMPA) on Simeulue island was low compared with the reefs in other management areas, including the Recreational Park (Taman Wisata Alam-RP) of Banyak Islands and the open access areas of Simeulue island and the south-west Sumatra coastline.

9 OBSERVATION SITES The Simeulue Islands and Banyak Islands are located in west Nanggroe Aceh Darussalam. The Simeulue Islands lie between 95,6 96,5 E and N and the Banyak Islands lie between 97 97,5 E and 2,35-2 N (Figure 1). The observations were conducted within 3 management areas: Community Marine Protected Areas (CMPA) (Kawasan Konservasi Laut Daerah) of Simeulue Island at Siumat Island and Pinang Island (sites: 1, 2, 4, and 5) Recreational Park (RP) (Taman Wisata Alam), covering all of Banyak Islands and the surroundings (based on SK Menhut No.596/Kpts-II/1996) Utilization Areas (Daerah Pemanfaatan) which are not regulated by particular management or protection system. Figure 1. Survey locations in Simeulue Island and Banyak Islands, Aceh

10 CORAL REEFS A. Live coral coverage All observations on live coral cover were conducted using 4 x 5 m transects laid in series 5 m apart at 2-3 m depth. Each transect was divided into 1 points (5 between points) where benthic characteristics including coral genus, soft coral, algae and substrate type were identified. The ecological characeristics of Simeulue and Banyak Islands are strongly affected by the Indian Ocean. The highest hard coral coverage was 81%, recorded from Ujung Pulau Cut, Sumatra (Site 18), while the lowest hard coral coverage was 1% recorded at Siumat Island 1 (Site 1), Simeulue Island (Figure 2). Analysis of live coral condition within the CMPA region of Simeulue Island showed mean coral cover as low as 18% compared with the RP region in Banyak Islands of 38% and the utilization area in Simeulue (35%) and Sumatera (64%) (Figure 3) Hard Coral Cover (%) Figure 2. Mean (±SE) live coral cover at 35 sites on Simuelue Island, Banyak Islands and the Sumatran coast. Recreational Park Community MPA Utilization Area Utilization Area 9 8 Hard Coral Cover (%) (+/-) 1SE Community MPA Utilization Area Recreational Park Utilization Area Figure 3. Mean (±SE) of live coral cover based on management areas on Simuelue Island, Banyak Islands and the Sumatran coast. Simeulue Island Banyak Islands Sumatra

11 B. Recruitment of hard coral Data on coral recuitment was collected every 1 m using 5 x 5 quadrats along each transect used to record benthic substrate cover. Twenty replicate quadrats were measured along the 4 x 5 m transects at each site. Coral recruitment may indicate the recovery rate of reefs following disturbance. The highest abundance of coral recruits (8 recruits m -2 ) was recorded at Mata Nurung 1, on Simeulue Island (Figure 4). C. Genera diversity of hard coral To measure the diversity of hard coral genera, we used a modification of Simpson s Diversity Index (Krebs, 1989) : D = 1 - pi 2 and pi = ni/nt; pi = % composition of each genus (i) in one observation unit, ni = number of hard coral colonies for each genus (i) and Nt = total number of all genera. The highest Simpson s Diversity Index (D) would approach a value of 1, showing that the diversity of coral genera is high relative to the total number of coral colonies within an area. The diversity of coral genera in Ujung Pulau Cut (Site18) was the highest (.827) among all sites, with the lowest (.85) recorded from Pinang Island, Simeulue (Site 5). In this study coral recruits were identified and recorded as those less than 4 in length. An area with abundant recruits is worthy of protection since it may indicate an area suitable for coral growth and may also reveal, in part, the capacity of a reef to recover from disturbance or its resilence Coral recruits (no.m -2 ) Figure 4. Mean (±SE) number of coral 2 recruits (no.m -2 ) at 35 sites on Simuelue Island, Banyak Islands and the Sumatran coast. Recreational Park Community MPA Utilization Area Utilization Area Simpson's Diversity Index Figure 5. Mean (±SE) Simpson s diversity.2 index of hard coral genera (Indeks.1 Simpson s) at 35 sites on Simuelue Recreational Park Community MPA Utilization Area Utilization Area Island, Banyak Islands and the Sumatran coast.

12 REEF FISH COMMUNITY A. Species richness of reef fishes We recorded 36 reef fish species from 48 families of reef fishes at the 35 sites. The highest species richness of reef fishes was 139 species collected from inside the utilization area, Ujung Pulau Cut on the west coast of Sumatera (Site 18), and the lowest was 66 species from Mata Nurung, Simeulue Island (Site 7), also in the utilization areas. The mean of total species among management areas was relatively similar, with 111 species in RP, 11 in CMPA, and 11 in utilization areas. (Figure 6). The family Pomacentridae had the highest number of species and comrised 17% of the total reef fish abundance. It was followed by the Stuart Campbell family Labridae with 14% of total reef fish abundance (Figure 7). Also recorded for the first time in Indonesia was a species of parrotfish Chlorurus rhakoura (Scaridae) at Ujung Pulau Cut (Site 18), on the west coast of Sumatra and on Simeulue Cut Island on Simeulue (Site 14). Chlorurus rhakoura was found at site 18 on the west coast of Sumatra and on Simuelue Cut Island on Simuelue (Site 14). Prior to the present study this species was had only been recorded previously in Sri Lanka and in east Indian Ocean. There was no previous record of this species in Indonesia. Komposisi Family Ikan Karang POMACENTRIDAE 17% LABRIDAE 14% SCARIDAE 7% SERRANIDAE 6% SIGANIDAE 4% APOGONIDAE 3% BALISTIDAE 3% CAESIONIDAE NEMIPTERIDAE 2% 2% HOLOCENTRIDAE 2% LUTJANIDAE 3% M ULLIDAE CHAETODONTIDAE 8% ACANTHURIDAE 8% OTHERS 15% 3% POMACANTHIDAE 3% Number of species (no.) Taman Wisata Alam KKLD Open Access Open Access Kepuluan Banyak Simeulue Sumatra Figure 6. Family composition (left) and total number of species (right) of reef fishes, found at 35 survey sites.

13 B. Biomass and abundance of reef fishes Surveys on reef fishes were conducted to collect data on the frequency and total length of fishes along 3 replicate 5m belt transects at 2-4m depth. Small fishes with a total length <1 were recorded along 2 m wide belt along each transect, while fishes with total length >1 were recorded along a 5 m wide belt transect. Biomass of reef fishes (kg.ha -1 ) was calculated by converting total length to weight using the formula: W = a L b ; W = weight (kg), a and b = constant, L = total length (). Identification of species was according to Allen et. al (23), and information on trophic groups was sourced from Fish Base 2 (Froese and Pauly, 2). Our results show that the highest biomass of fishes ( kg ha -1 ) was found at Lambudong Island, Banyak Islands (Site 33) while the lowest ( kg ha -1 ) was at Mata Nurung 1, Simeulue Island (Site 7, Figure 7). Fish families that dominated the survey were Acanthuridae, Pomacentridae, and Scaridae. Among the three types of management areas of the Banyak- Simeulue region, the biomass of reef fishes in RP was the highest ( kg ha -1 ), while the lowest ( kg ha -1 ) was recorded from CMPA sites (Figure 8) Reef fish biomass (kg ha -1 ) Recreational Park Community MPA Utilization Area Utilization Area Figure 7. Mean (±SE) biomass of reef fishes (kg ha -1 ) at 35 sites in Simuelue Island, Banyak Islands and the Sumatran coast. 8 Reef fush biomass (kg ha -1 ) Recreational Park Community MPA Utilization Area Utilization Area Figure 8. Mean (±SE) biomass of reef fishes (kg ha -1 ) in each management area.

14 Abundance of reef fishes in Pulau Asok, Banyak Islands (Site 32) was the highest among all sites (3358 no.ha -1 ) while the lowest was in Pinang Island 1 (386 no.ha -1 ), located within the CMPA area of Simeulue Island (Figure 9). The highest mean reef fish abundance among management areas was in the Banyak Islands (151 no.ha -1 ), the utilization area of west coast Sumatra (14333 no.ha -1 ), and the utilization area of Simeulue Island (977 no.ha -1 ) (Figure 1). 6 5 Reef fish abundance (no.ha -1 ) Figure 9. Mean (±SE) abundance of 1 reef fishes (no ha -1 ) at 35 sites in Simuelue Island, Banyak Islands and the Sumatran coast. Recreational Park Community MPA Utilization Area Utilization Area 25 Reef fish abundance (no.ha -1 ) Figure 1. Mean (±SE) abundance of reef fishes (no.ha -1 ) in each management Recreational Park Community MPA Utilization Area Utilization Area area.

15 C. Composition of reef fish biomass and abundance The biomass and abundance of the six most common major families; Acanthuridae (surgeonfish), Chaetodonthidae (butterflyfish), Labridae (Wrasses), Pomacentridae (damselfish), Pomacanthidae (angelfish), and Scaridae (parrotfish) are shown by management type (figure 11a and 12a) and by size class (Figures 11b and 12b). The biomass of family Acanthuridae was highest at all sites within each management area ( kg.ha -1, Figure 11a), while the biomass of Pomacentridae and Scaridae was also higher than the 3 families of Cheatodontidae, Labridae and Pomacanthidae. The family Pomacentridae was the most abundant family of all management areas ( no.ha -1, Figure 12a). Despite these differences in the biomass and abundance among the 6 major fish families, no clear differences could be seen in composition of fish families among management areas. In terms of biomass, most fish were recorded within the 5-25 size class with highest biomass genereally recorded for fish within the Banyak Islands and Sumatran coast utilization areas. The highest numbers of fish were recorded in the 5-1 size cohort. Interestingly, the relatively low abundance of the -5 size cohort compared with the 5-1 cohort (Figure 12b) suggests that Pomacentridae and Labridae, which commonly comprise most of the -5 sized fishes, were often >5 in length (Figures 11a and 12a) Reef fish biomass (kg ha -1 ) ACANTHURIDAE CHAETODONTIDAE LABRIDAE POMACANTHIDAE POMACENTRIDAE SCARIDAE 5 Figure 11a. Mean (±SE) biomass of 6 major reef fish families (kg ha -1 ) in each Recreational Park Community MPA Utilization Area Utilization Area management area Reef fish biomass (kg ha -1 ) Banyak Islands Recreational Park Simeulue Island Community MPA Simeulue Island Utilization Area Sumatra Utilization Area 5 Figure 11b. Mean (±SE) biomass of reef fishes (kg ha -1 ) based on size class for each >4 management area.

16 12 1 Reef fish abundance (no. ha -1 ) ACANTHURIDAE CHAETODONTIDAE LABRIDAE POMACANTHIDAE POMACENTRIDAE SCARIDAE Figure 12a. Mean (±SE) abundance of 6 major reef fish families (no ha -1 ) in Recreational Park Community MPA Utilization Area Utilization Area each management area Reef fish abundance (no. ha -1 ) Banyak Islands Recreational Park Simeulue Island Community MPA Simeulue Island Utilization Area Sumatra Utilization Area Figure 12b. Mean (±SE) abundance of reef fishes (no ha -1 ) based on size >4 classes in each management area.

17 MACRO INVERTEBRATES Some species of marine macro-invertebrates are important ecological indicators of reef health. Counts of invertebrates were made within two replicate belt transects (1 x 1 m) on the reef flat at 2-3 m depth. We recorded several key indicator species of giant clams (Tridacnidae), Crown of thorns starfish (Acanthaster planci) and sea urchins (Echinoidea). Of the 35 sites in the Simeulue and Banyak Islands, giant clams were in highest abundance in the Banyak Islands. The highest abundance was 13, per hectare in Ujung Sialit, Banyak Islands (Figure 13). Four species of giant clams were recorded; Tridacna crocea, T. maxima, T. squamosa, and T. gigas. The most common species was T. crocea which comrpised 79% of total giant clams found during the survey (Figure 14). Acanthaster planci was abundant in several locations in Banyak Islands. The highest abundance was 16 per hectare, found in Baguk Island (Site 35). The high abundance of A. planci at one site had caused significant mortality to the surrounding reefs (Figure 15). In Asin Bay (Site 25) and Rangit Besar Island (Site 34), A. planci had severely damaged the reef with greater than 9% coral mortality. We discuss this phenomenon in the next chapter. The largest number of sea urchins was recorded from Siumat Island (site 2) with 1,5 animals per hectare. The most abundant species was Echinostrephus malaris, comprising 89% of total species of sea urchins recorded. Also recorded were Echinothrix calamaris, Mespilia globulus, Diadema savignyi, Diadema setosum, and Echinometra mathaei. 16 Tridacnidae abundance (no.ha -1 ) Figure 13. Mean abundance (± SE) of giant clams (Tridacnidae) at 35 sites in Simuelue Island, Banyak Islands and Sumatra. Recreational Park Community MPA Utilization Area Utilization Area Percentage of species of Tridacnidae T. maxima 13% T. crocea 79% T. gigas % T. squamosa 8% Figure 14. Species composition of clam (Tridacnidae) found at 35 sites in Simuelue Island, Banyak Islands and Sumatra.

18 9 8 COTs abundance (no.ha -1 ) Figure 15. Mean abundance (no ha -1 ± SE) of Acanthaster planci at 35 sites at Simuelue Island, Banyak Islands and the Sumatra coast; the red line 1 denotes the number at which an invasion has occured. Recreational Park Community MPA Utilization Area Utilization Area 45 4 Sea urchins abundance (no.ha-1) Figure 16. Mean abundance (± SE) of sea urchins (Echinoidea) at 35 sites at Simuelue Island, Banyak Islands and the Sumatra coast. Recreational Park Community MPA Utilization Area Utilization Area Percentage of Sea Urchin species Echinostrephus malaris 89% Echinothrix calamaris 2% Echinometra mathaei 2% Diadema setosum 5% Mespilia globulus % Diadema savignyi 2% Figure 17. Species composition of sea urchin (Echinoidea) at 35 sites at Simuelue Island, Banyak Islands and the Sumatra coast.

19 Simeulue and Banyak Islands are located at the juncture of two continental shelves, the Indo-Australia and Euroasian. On March 28, 25 an earthquake of 8. on the Richter scale, known as the Nias Earthquake occurred due to the subduction of the Indo-Australia shelf under the Euroasia shelf. The impact of this earthquake on the surrounding areas (Simeulue, Banyak Islands, west coast of Sumatra) was davastating with destruction to homes and lives. The earthquake uplifted Simeulue island by m. For the most of the 3 km coastline of Simeulue Island, the coral reef at 1-3m depth was uplifted and currently remains exposed. In some reef areas, the up-lifted and now dead reefs were still intact allowing identification of the coral species from corallite structures. Several species previously dominant at 1-3m depth, and now exposed, were absent in the live hard coral community growing at 1-3m depth. For example, at Detimon on Simeulue Island (Site 18), we found numerous intact and dead colonies of Seriatopora, above high tide but the genus was not found within living communities at 1-3m depth during the survey. The shift in community structure was also observed by comparing coral species diversity from below and above water transects. At Mata Nurung 2 at Simeulue Island (Site 13) the percent cover of uplifted dead corals and shallow water live corals living at 1-3m depth did not differ (Figure 18), but species composition of the live communities had changed, from Acropora spp. dominant communities before the earthquake to Porites spp. dominant communities after the earthquake (Figure 19). The mass mortality of corals caused by the Nias earthquake is possibly one of the largest single extinctions of coral reefs recorded. In many reef locations, coral species that were once abundant and colonized shallow waters at 1-3m depth prior to the earthquake are starting to recruit into these habitats and develop into small colonies in shallow waters. It will undoubtedly take a long time for the process of natural recovery to take place. Collaborative efforts among all stakeholders are required to reduce threats and overexploitation from fishing pressure will be one of the most effective ways to help coral reef recovery. In the coastal area of Singkil District and some parts of Banyak Islands the land subsided and in some areas was flooded by seawater. Numerous houses at the beach were abandoned by the owners because of heavy damage and salrpter inundation. The community has since been using live corals to build protective walls and barriers against the tidal inundation. Alternative solutions to this problem required that governments and stakeholders provide assistance to reduce the dependence by commuinities on live coral harvesting and promote the use of substitute building materials.

20 Anthony O Toole Anthony O Toole Colonies of Acropora which were up-lifted to the surface on Simuelue Island by the Nias earthquake in March 25. Several colonies are still intact and allowed scientists to identify them to species level. Massive pieces of hard coral were arranged neatly to be used as foundation materials for housing on Banyak Island Hard coral cover (%) Hard coral cover (%) Shallow water Uplifted Acropora Heliopora Pocillopora Montipora Porites Favites Favia Pavona Platygyra Coeloseris Hydnopora Psammocora Astreopora Galaxea Goniastrea Goniopora Leptastrea Leptoria Lobophyllia %shallow %uplifted Figure 18. Comparison between the mean (±SE) hard coral cover in shallow waters and uplifted reef of Site 8, Mata Nurung, Simuelue Island. Figure 19. Comparison between the percentage cover of hard coral genera in shallow waters and uplifted reef at Site 8, Mata Nurung, Simuelue Island. The invasive crown of thorn starfish (COT), Acanthaster planci was also recorded in locations in the Banyak Islands. We recorded as many as 61 individuals within one hactare at Site 35 (Figure 16), while the highest abundance was recorded at Site 28, 29, and 34. Greater than 3 individuals per hectare was defined as an outbreak (IUCN, 24). Based on this, many sites within the Simeulue and Banyak Islands had experienced COT outbreaks and at some sites had caused coral mortality of up to 9% of corals (eg. Asin Bay, Site 25).

21 The outbreak of COTs was found at 11 of the 17 sites in the Banyak Islands and 5 of the 16 sites in the Simeulue islands. An indication that COTS were spreading throughout the Banyak Islands was the presence of COTs in areas of high coral cover, such as Site 35. The invasion of COTs at this site was recent as damage to coral colonies was still low, the substantial damage at other sites raises concern that this invasive marine invertebrate can spread from site to site and damage coral reefs throughout the region. The causes of invasive COT outbreaks include: a. Natural phenomena; b. The exploitation of predators including triton shell (Charonia tritonis), triggerfish (Balistoides spp), and napoleon wrasse (Cheilinus undulatus), have allowed the starfish population to grow in the absence of predation; c. An increase in nutrient concentrations from anthropogenic and non-anthropogenic sources have boosted numbers of plankton in the surrounding waters and provided a food supply the larvae of the COT. The harvesting of COTs as a control measure to reduce the population spread has been used successfully in some coral reefs where areas are easily defined, small (1-2 ha) and reefs are separated from other reef or larval sources. The harvesting or poisoning for eradication requires extensive manual labour, organisation and repetitive attempts over many months until the population is controlled and eliminated. Coordination and collaboration program at the local level is key to this undertaking. It is recommended that periodic monitoring and possible eradication of COT populations is required, especially in the Banyak Islands, to prevent further spread and mortality to coral reefs. Yudi Herdiana Andrew Baird High densities of Crown of Thorn Starfish (Acanthaster planci) were found in Rangit Besar Island, Banyak Islands. Widespread mortality by Crown of Thorn Starfish (Acanthaster planci), was found in Asin Bay, Banyak Islands.

22 1. The Simeulue and Banyak Islands contain a complex array of coral reefs, mangrove and seagrass habitats. Both island groups contain examples of coral reef ecosystems that remain in relatively good condition, with high live coral cover and a high diversity and abundance of reef fish. Protecting these remaining functional coral reefs is imperative given the high level of existing threat to their health including, coral mining, blast fishing, netting, cyanide fishing and predation by the crown of thorns starfish. Developing a series of marine protected areas that contain representative and replicated habitats for this region of south-west Sumatra is a critical step towards developing integrated coastal and marine conservation management for the region. 2. Alternative solutions developed by governments, NGO s and communities are required to provide assistance in reducing the dependence of commuinities on live coral harvesting and promote the use of substitute building materials. 3. Marine ecosystem surveys to fill in gaps in knowledge of ecosystem health especially on Simeulue Island and the Sumatran coast. 4. An urgent need for marine conservation outreach programs to increase community awareness on coral reef conservation issues. 5. A monitoring and eradication program is needed to evaluate the impact and investigate options for controlling the crown of thorn starfish in the Banyak Islands, to prevent further spread and mortality to coral reefs.

23 References Allen, G. R., R. Steene., P. Humann., N. DeLoach. 23. Reef fish identification-tropical Pacific. New World Publication, Inc. Odyssey Publishing, USA. Froese, R and Pauly, D. 2. FISHBASE 2. consepts, design and data sources. Philippines, ICLARM. 344pp Gomez, E.D. and Yap, H.T Monitoring reef Condition. In kenchington R A and Hudson B E T (ed). Coral Reef Hand Book.UNESCO regional Office for Science and Technology for South East Asia. Jakarta. IUCN. 24. Managing Marine Protected Areas, a toolkit for Western Indian Ocean. IUCN Eastern African Regional Programme, Nairobi, Kenya, xii + 172pp.