APPLICATION OF ALOS IMAGERIES FOR MONITORING CORAL HEALTH IN COASTAL WATERS OF VIETNAM. PI 326 Tong Phuoc Hoang Sơn Institute of Oceanography Viet Nam

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1 APPLICATION OF ALOS IMAGERIES FOR MONITORING CORAL HEALTH IN COASTAL WATERS OF VIETNAM. PI 326 Tong Phuoc Hoang Sơn Insttute of Oceanography Vet Nam 01 Cau Da street, Vnh Nguyen, Nha Trang Vet Nam, Phone number: ; Facsmle Number: ; Emal Address : tongphuochoangson@gma.com 1. ABSTRACT Coral reef s one of marne habtats have hgh prmary producton but also s hgh senstve. Due to comfortable condtons n humd tropcal regon, coral reef n coastal waters of Vetnam sea develop very well wth ther dstrbuton stretch along from North to South areas. Durng the past several decades, coral reefs n many parts of the world have been subjected to a seres of bleachng events, ncludng some coral reef areas n coastal waters of Vetnam. Ths report present some experences on the coral mappng n coastal area of Vetnam and results of applcaton for detecton of evdences of bad status of coral health due to affect by natural dsasters as well as anthropogenc nterventons. 2. INTRODUCTION Vetnam le n humd tropcal area wth coastal habtats such as coral reef, sea grass bed, mangrove forest, etc, develop very well. Coral reefs n Vetnam dstrbute along coastal areas from North to South as well as n offshore waters (Spratly and Paracell Archpelagos). Due to mportance aspect of ths habtats, many projects on the coral mappng have been carred out n coastal area of Vetnam (Nnh Thuan, Khanh Hoa, Phu Quoc, Da Nang, Quang Nam, ) but the assessment of natural dsasters that effect to coral reef s stll few. Effect of global warmng and ElNno s reasons causng coral bleachng n Con Dao, Phu Quoc slands n July 1998 (V S Tuan et all 2005) as well as Con Dao sland durng October 2005 (T. P. H Son et all 2006 [8] have been dscussed n some papers but how do we montor and detect the coral bleachng n coastal waters of Vetnam sea s opened. Ths report present some experences on the coral mappng n coastal waters of Vetnam and some evdences on affects of natural dsasters as well as human nterventons to the coral health base on the remote sensng technques. These results were obtaned from ALOS-JAXA project PI 326 wth ttle Applcaton of ALOS and Ocean Color Imageres sources for montorng of Coral Health n coastal waters of South of Vet Nam. 3. DATA AND METHODOLOGY Satellte mages: The remote sensng technques s man method for detectng the dstrbuton of coral reefs and assessment the status of coral health under affect of natural dsasters and anthropogenc nterventon. A seres of satellte magery as well as aeral photography have been used. They nclude ALOS (Japan) magery from Project Applcaton of ALOS magery for montorng the coral health n coastal waters of Vetnam wth 18 scenes AVNIR2 (10m) and PRISM (2.5m) have been used for detecton the dstrbuton n coastal waters n Quang Tr, Quang Nam, Bnh Dnh, Khanh Hoa, Nnh Thuan, Ba Ra Vung Tau and Ken Gang provnces FORMOSAT2 MS (8m) and PAN (2m): 16 scenes from SAKE Project have been used for detecton the dstrbuton n coastal waters n Quang Nam, Bnh Dnh, Khanh Hoa, Nnh Thuan provnces. Landsat ETM (30m) from USGS (2 scenes) usng for detect dstrbuton coral reef n coastal waters of Nnh Thuan provnce and Condao Archpelagos. SPOT4 (20m), SPOT5 (10m) from IFREMER project, Natonal Projects have been used for supplementng some nformaton on the dstrbuton of coral reef and related habtats n Con Co, Cu Lao Cham, Nam Du archpelagos The color aeral photograph dataset (nclude 18 scenes) takng n map scale 1/5.000 that cover whole of An Tho Archpelagos Phu Quoc Island Investgated data: They nclude underwater surveyed data by dfference methods on many of coral stes n coastal waters of Vetnam (fgure 1) those are: Surveyed data along coastal zone and surroundng the slands whch obtan by manta tow method (an nvestgaton method use for rapd assessment the dstrbuted components of coral reefs). Surveyed data along coastal zone and surroundng the slands whch obtan by reef check method (an nvestgaton method use for detal assessment the dstrbuted components of coral reefs along the coast accordng to shallow and deep sectons)

2 Surveyed data on the coral reef dstrbuted n the cross secton by method of bomass frame sectons. Surveyed data used for obtanng homogeneous substratum postons (such as sand, mud, rocky, ) for buldng the Depth Invarance Index algorthm use for removng the water column n studed area. On the specal term, t s called be method of water column correcton. In some case, we re-used the exsted sedment maps nstead of underwater surveyed data (fgure 2). Postons of key ponts help for clasfcaton (coral reef, seagrass beds, bed rock, sand,...) n Cu Lao Cham obtan from underwater survey durng May 2008, as an llustrated samples for obtanng underwater surveyed data (fgure 3) Fgure 2: Postons of sand stes help for calculatng the Depth Invarance Index n the Map of Sedment Dstrbuton n coastal waters of Quang Nam provnce Fgure 1: The studed stes (orange crcles) on coral reef dstrbuton n coastal waters of Vetnam by remote sensng technques lnkng wth underwater surveys 1) Tran Island; 2) Co To Archpelago 3) Cat Ba Archpelago; 4) Long Chau Archpelago; 5) Bach Long V Island; 6) Me Island; 7) Ngh Son Island; 8) Con Co Island; 9) Coastal water of Thua Then - Hue Provnce; 10) Cu Lao Cham Archpelago; 11) Coastal water of Quang Nam provnce; 12) Re Archpelago; 13) Xanh Island; 14) Van Phong Bay; 15) Nha Trang Bay; 16) Coastal Area of Nnh Thuan provnce Nnh Thuận; 17) Con Dao Archpelago; 18) An Tho Archpelago Phu Quoc Island; 19) Nam Du Archpelago; 20) Tho Chu Archpelago Fgure 3: Postons of Ground truthng ste help for clasfcaton (coral reefs, seagrass beds, bed rock, sand,...) n Cu Lao Cham Archpelago obtan from survey durng May Procedure of data processng for detecton the coral reefs and relevance habtats by remote sensng technque. Ths procedure have been carry out step by step as followng Geometry correcton (Geo-Reference): n order to convert btmap mage co-ordnate to local geography co-ordnate (UTM project, WGS84 datum) Radance correcton: convert Dgtal Number nto spectral radance n sensor by the convert formula appear as followng : Rad = a * DN + b ; when a: gan and b: offset Atmospherc Correcton: convert spectral radance nto reflectance n surface water and flter the atmospherc affects. In ths step we used Dark Subtract tool n ENVI software for processng.

3 Water Column Correcton: The lnear natural logarthm relatonshp of water reflectance between th band and j th band s basc formula for calculatng the Depth Invarance Index. It was showed as followng D.I.I j = a * Ln( ) - Ln( j) + b When -, j : are spectral reflectance n water surface of band par (,j) that obtan from atmospherc correcton n 128 sand ponts - a, b : are slope and ntercept n regresson lne, they appear strong (or not) relatonshp between band and band j by mean of Standard Devaton (r 2 ). The llustrated results of correlaton and regresson analyss n step of Water Column Correcton (for Cu Lao Cham case study n ALOS - AVNIR2 date 08 June 2008) show n fgure Ln (b2) y = 0.914x R 2 = Ln (b1) Ln (b3) y = x R 2 = Ln (b2) Ln (b4) y = x R 2 = Ln (b3) Fgure 4: Some lnear natural logarthm relatonshps of water surface reflectance between th band and j th band, that s basement for calculatng the Depth Invarance Index (from 128 sandy stes) n AVNIR2 mage cover Cu Lao Cham archpelago date 08 June 2008 (T.P.H Son, 2009 [12 ]) Equaton system of Depth Invarance Index of band pars obtan from ALOS-AVNIR2 base on 128 sandy pont takng n Cu Lao Cham case study have been showed as followng: D.I.I 12 = 0.914* Ln ( 1) - Ln ( 2) D.I.I 13 = * Ln ( 1) - Ln ( 3) D.I.I 14 = * Ln ( 1) - Ln ( 4) D.I.I 23 = * Ln ( 2) - Ln ( 3) D.I.I 24 = * Ln ( 2) - Ln ( 4) D.I.I 34 = * Ln ( 3) - Ln ( 4) The correlaton analyss also alow to choose only 5 new D.I.I bands (cancel D.I.I 13 for processng (r 2 < 0.6) for next classfcaton Mask step: allow to hde unstuded area.e : land, offshore where don t exst of coral reef and sea grass bed. Ths step wll enhance the mage qualty for classfcaton. Supervsed classfcaton: used Mahalobch Dstance classfcaton base on survey ponts n dfferent habtats for detecton the dstrbuton of coral reefs, sea grass beds and other substratum The remote sensng technques for detecton the evdences causng negatve affects to status of the coral health Detecton the reasons causng phenomena of coral bleachng: The coral bleachng can make the mass mortalty of benthos lve n coral reefs. Ths s a phenomena related strongly wth clmate change due to the ncreasng of sea water temperature, the decreasng the water salnty, the ncreasng the acdfcaton processes, By assessment the temporal and spatal varances of sea surface temperature, water salnty and sedment flux by ocean color and mult spectral mageres as well as the fndng out especal spectral color spots drectly n coral stes from hgh resoluton mage allow us to detect the phenomena of coral bleachng n somewhere of coastal water of Vet Nam.. Detecton some evdences of acdfcaton processes n offshore water of Vetnam. Increased fossl fuel burnng assocated wth geothermal phenomena and ndustralzaton, cement producton, land use changes assocated wth agrcultural actvtes are causng atmospherc CO2 concentratons. There s clear evdence that the carbonate equlbrum of the oceans s shftng n response to ncreasng atmospherc CO2 concentratons to rse, and at ncreasng rates. Even small changes n CO2 concentratons n surface waters may have large negatve mpacts on marne calcfes and natural bogeochemcal cycles of the ocean. For example, decreased carbonate on concentraton sgnfcantly reduces the ablty of corals to produce ther calcum carbonate skeletons (Kleypas et all, 2006 [3]) In Vetnam, the studes on the acdfcaton processes and the ncreasng of CO2 emsson that affect to coral health are very restrcted.

4 Our study only record on some evdences of potental geothermal phenomena n offshore Bnh Thuan waters as one of evdences of acdfcaton processes. By vsual nterpretaton drectly n color composte mage from a scenes of ALOS-AVNIR2 (date, 18 September 2007) allow us found out ths phenomena. Detecton the evdences of sedment and fresh water plume as well as sltaton processes causng the negatve effects to status of coral health. By fuson technque base on ocean color mage merged to ALOS PRISM one, we found out n some case the fresh water and sedment from n rver can be reach to offshore waters more 40 km and they caused negatve consequence to coral health n some coral stes. A very drect approach to mage enhancement s the use of hgh resoluton data, e.g. ALOS AVNIR2 Band 1 (10m) panchromatc mages, to sharpen mages of lower spatal resoluton, e.g. MODIS 250 m mults-pectral data. Once a set of mult-sensor mages s placed n regster wth a hgh resoluton reference mage, the dgtal numbers (DNs) of the varous mult-spectral bands may be merged wth those for the sngle band (panchromatc) reference mage usng technques prevously descrbed by Clche et al. (1985) [2]. These methods may be summarzed n the followng equatons: DN ' = * DN * DN( h) + (1) DN = ' * * DN * DN( h) + (2) Where: DN and DN ' are the DNs for the th band of the orgnal and fused mult-spectral mage, respectvely; DN(h) s the DN for the hgh resoluton reference mage;, are scalng factors; and and are weghtng factors. In realty condton, we used drectly tool Pan Sharpness n SPEAR tools of ENVI 4.4 software for resolvng ths problem. Detecton the evdences of anthropogenc nterventons causng the negatve effects to status of coral health. The coastal developed actvtes such as buldng the toursm resorts, dredgng marne ports, rregular materal dumpng, can causng the negatve consequences nto status of coral health. Base on spectral analyss for detectng the bottom bathymetry, vsual nterpretaton from color composte mages we saw a lot of cases of sltaton can be badly effected to status of coral health, destroyed and dsappearance of some coral stes n coastal waters of Vetnam. RESULTS AND DISCUSSIONS Dstrbuton of coral reefs n coastal waters of Vetnam sea. Base on remote sensng technques lnkng wth underwater surveys, the dstrbuted scenes of coral reefs n coastal waters of Vetnam sea have been detected. Fgure 5 s llustrated results on dstrbuton of coral reefs and related underwater habtats n Cu Lao Cham archpelagos and surroundng waters (Tong P H S, 2009 [12] ). Fgure 5: Dstrbuton map of coral reefs and sea grass beds n Cu Lao Cham archpelago obtan from remote sensng technques n AVNIR2 (date, 08 May 2008) [12] Note: HC: Hard coral, SW : Sea weed: SG : Sea grass ; RK : Rock; SD : Sand, Land Mask The detal dstrbuton of coral reefs n coastal water of Vetnam was recored as followng Dstrbuton of coral reefs n Northern sde of Vetnam sea: nclude coral reefs n Tonkn Gulfs (Co To archpelago, Tran Island, Cat ba, Bach Long V archpelago, ) and also coastal waters of North of Center such as Hon me (Thanh Hoa provnce), Ngh Son (Ha Tnh provnce ) and Con Co (Quang Tr) Untl now, we carred out to survey and buldng the dstrbuted maps of coral reef n Co To, Bach Long V and Con Co (Thao N.V and Son T P H, 2007 [ ]. The results present detal n fgure 5, and show that: In Co To archpelago, lve coral dstrbute scattered n small slands surroundng of archpelago, such as Co To Con, Kho, Ca Chep, Khoa Islands, and also North West of Thanh Lan Island wth total area estmated about 66.1 ha. Platform reef cover Death Coral n North of great Co To wth area reach to ha In Bach Long V Island, lve coral exsted n North and West sdes wth area reach to 133 ha, remaned area of reefs cover the death coral, wth estmated area s 491 ha. In Con Co Island, lve coral manly exsted n North sde wth estmated area s 72 ha. The southern sde cover the sandy materal nterpose wth rocky clffs Dstrbuton of coral reefs n Central of Vetnam sea: nclude coral reefs n Cu Lao Cham and n

5 coastal waters of Quang nam, Phu Yen, Khanh Hoa, Nnh Thuan provnces. The coral reefs n Cu Lao Cham. The lve coral manly dstrbuted n western and southwestern sdes of Lao Island and other small slets wth estmated area s 165 ha (T.P.H. Son, 2008 [12]. The coral reefs n these area develop well wth genus of Acropora, Montpora and Gonopora (Nguyen Van Long et all [6 ]). The North and East of Man Island of Cu Lao Cham cover manly of rocky clffs. The bo resources s very dffculty exsted and developed n these areas. The southern sde of Cu Lao Cham nclude coral reefs wth hgh cover level nterpose wth sand beaches and sea grass beds exst n Bac, Ong, Chong, Bm, Huong and Nom grounds. The coral reefs n coastal waters of Quang Nam provnce. Include frngng reefs and platform reefs exst surroundng of An Hoa cape. The platform reefs exst n the front of An Hoa Gap and great reef bank wth predomnant genus of Portes, Gonastrea, Platygyra. In An Hoa cape, the coral reefs cove manly of branch coral and soft coral wth predomnant of Acropora. The reef s narrow and deep. The total area of coral reefs n ths area have been estmated about 95 ha (T. P. Son, 2007 [11]). The coral reefs n coastal waters of Phu Yen Provnce: The coral reefs exst n the front of the mouth of Cu Mong lagoon. They have been met n Nom cape (3.5 ha), Hoa Thanh (6.9 ha) and Vnh Hoa (4.7 ha). The coral reefs exst n the front of the mouth of Xuan Da lagoon. They have been met n Tu Nham Cape (32.5 ha), Vung La (5.6 ha), Hon Thung ground (10.0 ha), Tuong ground (2.3 ha), Phu Ho cape (12.4 ha) and Yen cape ( 3.2 ha). In coastal waters from O Loan lagoon to An Phu Commune s regon where coral reefs develop very well and hgh cover level wth man component of soft coral such as Cu Lao Ma Nha (42.3 ha), Phu Thuong (9.9 ha), Yen Cape 30.2 ha, Go ground - An Chan (39.4 ha), Chua Island An Chan (32.7 ha) and Dua sland An Phu (8.3 ha) In coastal water of Ro gorge, coral reef have been seem Den Cape (11.6 ha), Ro Cape (18.8 ha), Phong So (11.2 ha) và Nua Island (17.4 ha). The coral reefs n coastal waters of Khanh Hoa provnce have been estmated about 3266 ha, (T.P.H.Son, 2007 [9] they dstrbute n man regons as followng: Coral reefs n Ben Go Bay get ha area, they man dstrbute n Bp, O, Dut, Cum Meo slands, Tuong, Trao banks Islands and also coastal waters of North West of Bay. Coral reefs n East coast get ha area. They dstrbute manly n Hon Gom penesula, Co Co channel, Great Island, and some slets n North of Great Island. Coral reefs n South-West coast get ha area. They dstrbute manly n Du cape, Hon Kho, My Gang, Ba Co grounds and some underwater banks. Coral reefs n Bnh Cang Bay nclude coral reefs n Nnh van, Hon Th Nha Phu Lagoon get ha. They dstrbute manly n Cay Bang bay, Long beach and Chao bank. Coral reefs n Nha Trang Bay get ha area. They dstrbute manly n around Hon Tre, Mun, Mot, Tam, Meu, Vung and Cau slands as well as n Song Lo and Grand bank. Coral reefs n Cam Ranh Bay get ha area. They dstrbute manly n Thuy Treu bank, East coast n Cam Ranh penesula, No, Ngoa, Bnh Ba Island. In coastal waters of Khanh Hoa provnce have been characterzed by creatng of platform reefs n bg deep such as Grand bank 426 ha, Thuy Treu Band 800 ha, (fgure 6) Nnh Phuoc band 40 ha and Chao Bank 13 ha Fgure 6. Some typcal platform reefs n coastal waters of Khanh Hoa provnce Grand Bank (upper), Thuy Treu Bank (lower) The coral reefs n coastal water of Nnh Thuan provnce: have been estmated about 1277 ha (Son. T.P.H, 2005 [7], they dstrbute n man regons as followng

6 The coral reefs n coastal waters of Nnh Thuan Provnce: The narrow non-typcal frngng reefs exst n man areas: Hon Chut to Da Vach Cape - 42 ha, Vnh Hy Gorge - 28 ha, Hon Do My Tuong 98 ha Tha An ground s a The typcal frngng reef exst n many grounds of coastal areas : Tha An ha, Tu Then (151 ha), Son Ha (182 ha). The platform reef exst n Breda Bank wth area of 84 ha Besde n deep sea, the coral reefs also exst n m deep, exst a reef ground that cover manly by horn coral speces wth 168 ha area Dstrbuton of coral reefs n Southern sde of Vetnam sea. The coral reefs n Con Dao archpelago: The coral reefs get a total area of ha and sea grass beds get a total area ha, Son. T.P.H, 2010 [13] wth detal dstrbuton present n table 1 Table 1: The dstrbuton of coral reefs and sea grass bed n Con Dao archpelago Coral reef S (ha) Sea grass bed S (ha) Great lagoon Great lagoon South ConLon Isl 18.8 South ConLon Isl Ba Island 31.1 Ba Island 10.3 Ben Dam Lagoon Ben Dam Lagoon 78.6 Ong Dun ground 26.7 Ong Dun ground 31.2 OngCuong ground 19.7 OngCuong ground 9.0 Dam Tre Lagoon 35.2 Dam Tre Lagoon 33.8 Dam Tre cape 9.2 Dam Tre cape 14.5 Chm Chm cape 7.8 Chm Chm cape 32.4 Great Tre Island 16.4 Great Tre Island Small Tre Island 1.5 Small Tre Island Great Trac sland 13.1 Great Trac sland Small Trac sland 22.5 Small Trac sland Trac sland 6.8 Trac sland Bay canh Island Bay canh Island 49.2 Cau Island 20.6 Cau Island The coral reefs n An Tho archpelago and Phu Quoc Island nclude 119 ha n North West of Phu Quoc Island (table 2), 350 ha n An Tho Archpelagos (table 3) and 9800 ha of sea grass beds n coastal areas of Phu Quoc (table 4), Son. T.P.H, 2010 [13]. Table 2. The dstrbuton of coral reefs and sea grass bed n Nouth West of Phu Quoc Island Stes S (ha) Stes S (ha) Cua Can cape 50.0 Do Mo Island 2.1 Ong Quo Cape 35.0 Thay Bo Island 0.6 Ghenh dau Cape 30.9 Bang Island 0.7 Table 3 : The dstrbuted area of coral reefs n An Tho Archpelago Stes S Stes S (ha) (ha) Dam Trong Island 12.5 Xuong Island 24.3 Dam ngoa Island 6.8 Gam Gh Island 26.2 Dua Island 18.8 Mong tay Island 3.8 Ro Island 30.0 May Rut Ngoa Isl 29.4 Thom Island 44.2 May Rut Ngoa Bank 18.0 Trang sland 5.5 May Rut Trong Island 25.6 Kho Island 4.2 Km Quy Island 9.1 Vang sland 39.0 Km Quy Bank 52 The coral reefs n Nam Du archpelago have been estmated about 242 ha wth detal dstrbuton n table 4 Table 4 : The dstrbuted area of coral reefs n Nam Du Archpelago Stes S (ha) Stes S (ha) Nam Du Island 71.7 Bo tra sland 14.5 Co Loa Island 1.6 Mau Island 17.7 Moc Island 1.3 Nom Ngoa Island 3.0 Gang Island 15.8 Nom gua sland 6.9 Truoc Island 10.3 Nom Trong Island 1.5 Dau Island 24.9 Underwater Banks n 16.5 West of Nom Island Ngang Island 33.6 Underwater Banks n 10.9 South of Nom Island Dam Island 2.4 Underwater Banks n South Truoc Island 10.1 The coral reefs n Tho Chu archpelago: Total area of coral reef have been estmated ha and sea grass bed wth ha (table 5), Son. T.P.H, 2010 [13] Table 5 : The dstrbuted are of coral reefs n Tho Chu Archpelago Coral reefs - Frngng reef S (ha) Coral reefs platform reef S (ha) Tho Chu Isl 66.0 South of Xanh Isl Tu Island 47.9 SW of Ca Ban Isl 12.0 Cau Island 3.1 North of Cau Island 33.6 Xanh Island 4.0 Nhan Island 14.8 Ca ban Island 2.4 Cau Cat Island 4.4 Kho Island The evdences makng negatve affects to status of the coral health: nclude the coral bleachng, acdfcaton

7 phenomena, sedment and fresh water flux, sltaton and human nterventon The coral bleachng event and mass mortalty of benthos n Condao durng Md of October of Con dao Islands le n Southern of Vetnam sea n geography bounders from 106 o 31 to E longtude and 08 o o 45 N Lattude. Area of coral reef n Con Dao Island have been estmated about 1,000 ha. They have hgh bodversty wth 323 scleractnan speces, 202 speces of coral fsh, 148 mollusk speces, 110 crustacean speces, 44 echnoderm speces and 125 polychaete speces (Vo S. T et all, 2005) [15]. By mean of prevous studes (Vo. S.T, 2000 [14]), natural dsaster s consder as one of the best mportant reasons whch cause the bodversty degradaton of coral reef n Con Dao. The typcal examples of effects of Lynda Typhoon (1997) and of El Nno (1998) wth hgh ncreasng of sea water temperature and causng serous coral bleachng n Con Dao have been also recorded (Vo S Tuan, 2000) [14]. Durng Md October of 2005 an event of mass mortalty of the corals and benthos occurred agan n surround waters of Con Dao Islands, Ben H.X et all, 2008 [1] (fgure 7) Base on satellte data (Ocean color and Landsat ETM+) and also surveyed data from VOS-Nppon vessel, we found out the reasons causng the coral bleachng n Con Dao Island durng md of October 2005 (fgure 8) The random concdence of the extreme ncrease of sea surface temperature wth lower reducng sea water salnty as well as hgh turbdty (manly due to water plume from Mekong rvers) durng th October 2005 s man reason causng mass mortalty of corals and benthos n Con Dao Island Fgure 8. The terrestral, warmer fresh water plume wth hgh turbd reach more 200 km (from rver mouth) are man reasons causng coral bleachng and mass mortalty of benthos n Condao sland (T.P.H Son, et al, 2006 [8]. Fgure 7: Some pctures of coral bleachng and mass mortalty of coral n Condao Island durng October 2005 (after Hoang Xuan Ben et all, 2008 [1] ) Durng March Aprl of 2010, from survey data we also recorded the extreme ncreasng of sea water temperature and decreasng of water salnty n some places (Van Phong Bay, Con Dao Island, Tho Chu and Nam Du archpelagos,...) These results show clearly two perods wth extreme anomaly of hghest sea temperature and lowest salnty occur durng October 2005 (lght purple lne) and second perod of March to June (dot pnk lne) of 2010 (fgure 9). Latupov and hs colleagues [5] by SCUBA surveys from cooperaton Vet Russan nvestgaton on Oparn Researcher Vessel durng March of 2010 also found out the coral bleachng n Nam Du and Tho Chu archpelago wth strong rate.

8 Regret, by ALOS and any satellte magery sources we have not found out ths phenomena yet. Ths phenomena wll expand the acdfcaton process n here and effect drectly to coral reefs n Phu Quy sland 32 SST ( C) T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T S T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 Fgure 9. The monthly varance of Sea Surface Temperature (upper) and Sea Surface Salnty (lower) n offshore of Con Dao Island, show that 2005 and 2010 can causng the coral bleachng due to hghest water temperature and lowest sea water salnty The ol seep process n geothermal center and acdfcaton process n Phu Quy Island: Phu Quy Island or Cu lao Thu sland place n center coordnate about 109 o 58 E and 10 o 30 N where exst many ancent volcanoes. Accordng to French authors, on 2nd March 1923, there was an erupton at Tro sland (10 o 16 N, 109 o 01 E) whch produced scoraceous basalt. The erupton stopped on 13th May 1923, and ths sland were eroded below sea level (the recorded materal s mssng) The studed results of Pham Van Thom (personal nformaton) also recognzed that, ths area s bggest geothermal center of Vetnam. When we consder the reason that causng the ol slck attack on many toursm resorts of Vetnam durng 2007, we searched a lot of AVNIR2 and found out a yellow trace appear n Phu Quy Island n scene of ALOS - AVNIR2 date 27 July 2007 (fgure 10). Combnaton all of exsted data, we suggest on phenomena of ol seep n Eastern sde of Phu Quy sland. Fgure 10. The yellow track from RGB321 color composte mage (AVNIR2 date 17 July 2007) allow to suggest on formaton of natural ol seep and acdfcaton processes n Phu Quy sland The sedment and fresh water plume from rver after flood events affect badly to status of coral health. As presented, n secton 4.2.1, the terrestral, warmer fresh water plume wth hgh turbd from rver can cause serous damage to coral reefs. However, not all of tme, we can search a sutable satellte mage wth hgh resoluton (e.g, AVNIR2, SPOT5, Landsat...) for detecton the sedment and fresh water plume after flood events (especal the cloud cover level n these perods s very hgh). By combnaton between ocean color mages and hgh resoluton satellte mages sometme we can overcome above dsadvantage (fgure 11) Fgure 11. Inundaton area n downstream of Thu Bon Rver and sedment plume after Sangsane typhoon reach to CulaoCham sland by fuson technques between MODIS (250m) and Band 1 - AVNIR2 (10m)

9 The processed data show that the fresh water and sedment plume from rver Thu Bon can reach to North sde of Cu Lao Cham Island (108 o 30 E, 15 o 57 N) and badly affect to coral reefs n ths area The coastal development actvtes and ther affect to status of coral health. The coastal developed actvtes such as buldng the toursm resorts, dredgng marne ports, rregular dredged materal dumpng, can causng the negatve consequences nto status of coral health. For nstance, Nha Trang Bay s not only Marne Protecton Area but also s one of famous toursm stes of Vetnam. There are a lot of toursm constructors were bult n coastal area where exst coral reef and they destroyed a part or make dsappearance completely coral reefs and related habtats n these areas. The Dam Ga ground n North West of Tre Island (Nha Trang bay) exstence a coral reef (21 ha) le mxng wth sea grass bed (12 ha) n surroundng. Before 2005, ths was an deal ste for snorkelng actvtes and an excurson ste for tourst but after that VnaPernLand resort was formed and ths reef was destroyed step by step and dsappeared completely durng 2008 (fgure 12) Some coral stes n coastal waters of Vetnam such as Ba Ten Duong De, Tam Island (Nha Trang Bay), My Gang (Van Phong Bay), also le n smlar crcumstance The dredgng actvtes n marne ports and dredged materal dumpng can also cause the negatve effects to coral reefs n coastal water. By mean of spectral analyss n an AVNIR2 scenes (date 17 July 2007) for extractng the bottom bathymetry n South of Nha Trang Bay (T.P.H.Son, et all 2007), we also fount smultaneously out the underwater hlls (fgure 13). They appear suddenly (July 2006) and were dsappeared n next year (19 May 2008). Fgure 13. The appearance of underwater hlls n South of Nha Trang that formed from dredged materal dumpng (extract from AVNIR2 mage) Fgure 12: Dam Ga Gorge n Nha Trang Bay before (4/2004) and after (7/2007) buld VnaPear Resort. It make to dsappear 50 ha of coral reefs and 12 ha of sea grass beds. (after, T.P.H. Son, et all 2007 [9]) They cause the sltaton and server affect drectly to frngng coral reefs n Mun, Mot, Tam Islands and also platform reef Thuy Treu Bank le on Southern sde. The surveys from sedment traps n Nha Trang Bay (Latupov, Malyutn, 2006, [4], N.V.Long (cte from Son.T.P.H 2007 [9] also recorgnzed these events. 4. CONCLUSIONS Base on the abundance satellte mages nclude AVNIR2 manly from JAXA ALOS project and other sources such as SPOT4-5, Formosat2, Landsat ETM+ as well as aeral photographs, the area and dstrbuted maps of almost coral stes n coastal waters of Vetnam have been detected. In North sde, nclude coral reefs n Coto archpelago (256 ha), Bach Long V ( 133 ha) and Con Co (72 ha)

10 In Central regon, nclude the coral reefs n Cu lao Cham archpelagos (165 ha), the coastal waters of Quang nam provnce (95 ha), the coastal waters of Phu Yen provnce (303 ha), the coastal waters of Khanh Hoa provnce (3266 ha), the coastal waters of Nnh Thuan provnce (1000 ha). In southern sde and n Thaland Gulf (only n Vetnamese terrtory), nclude coral reefs n Con Dao archpelago (743 ha), An Tho archpelago and Phu Quoc Island (469 ha), Nam Du archpelago (242 ha) Tho Chu archpelago (134 ha). By mean of the remote sensng technques, we also detected the seres of the evdences causng negatve affects to status of the coral health, those are: The coral bleachng event and mass mortalty of benthos n Condao archpelago durng Md of October of 2005 and also at March to June of The ol seep process n geothermal center and acdfcaton process n Phu Quy Island. The sedment and fresh water plume from rver after bg flood event affect badly to status of coral health. The coastal development actvtes and ther affect to status of coral health The reason causng above phenomenon related to natural dsaster, global clmate change as well as anthropogenc nterventon. Ths report showed bg potental for applcaton of ALOS magery for montorng the status of coral health n coastal waters of Vetnam sea. 6. REFERENCES [1] H.X. Ben, Vo S T, Hoang P.K, 2008 Mass mortalty of corals and reef lvng features at Con Dao archpelago (Vetnam) n October Journal of marne scence and technology. Ser 8, No 1, 2008: [2] Clche, G., Bonn and P. Tellet, Integraton of the SPOT Panchromatc Channel nto ts Multspectral Mode for Image Sharpness Enhancement. Photogrammetrc Engneerng and Remote Sensng, Vol. 51, No.3, pp [3] Kleypas, J.A., R.A. Feely, V.J. Fabry, C. Langdon, C.L. Sabne, and L.L. Robbns, Impacts of Ocean Acdfcaton on Coral Reefs and Other Marne Calcfers: A Gude for Future Research, report of a workshop held Aprl 2005, St. Petersburg, Florda, USA. [4] Latypov Yu.Ya., Malyutn A.N New data on the dstrbuton of corals on the reefs n Voetnam // Bology of the Marne Invertebrates. Vladvostok: FEB, USSR Academy of Scences. P (n Russa) [5] Latupov. Ya.Yu et all, Reef buldng coral and reefs of Vetnam, the scentfc report n the Jont Russan- Vetnamese project of the Insttute of Marne Bology RAS and Insttute of oceanography VAST Bodversty and reproducton ablty n coral ecosystems of Vetnam [6] N.V. Long, Vo,S.T, Hoang P.K, Tuyen H.T, 2006, Conservaton of marne bodversty: a tool for sustanable management n Cu Lao Cham Islands, Quang Nam Provnce. Proceedngs of the 10th Internatonal Coral Reef Symposum, Oknawa, Japan 28 June-2 July : [7] T.P.H.Son, The coral mappng n coastal waters of Nnh Thuan provnce. The fnal report of ICRAN project, Nha Trang, pages. [8] T.P.H Son, Lau Va Khn, Hoang Xuan Ben, Tan Chun Knee, Joj Ishzaka, Vars Rans, Sarat Trpathy (2006). Dscuss on the man reasons causng mass mortalty of coral and benthos n Con Dao Island durng October In Proceedng of 2006 NAGISA conference Kobe Japan [9] T.P.H. Son, et all 2007, The status on dstrbuton and bodversty on coral reef n coastal water of Khanh Hoa provnce. The fnal report of provncal project, Nha Trang, 2007 (n Vetnamese) [10] T.P.H. Son and N.V. Thao, 2007, The dstrbuton of coral reefs n coastal waters of Vetnam sea from remote sensng data combne wth underwater surveys. The fnal report on natonal project , Nha Trang, 2007 (n Vetnamese) [11] T.P.H Son, The dstrbuted coral reef n coastal watres of An Hoa Quang Nam provnce. In the fnal report of ICZM project n Coastal Area of Quang Nam provnce, Nha Trang, 2007, pp (n Vetnamese). [12] T.P.H Son, The dstrbuted coral reef map n Cu Lao Cham archpelago detect from remote sensng technque, the scentfc report of LMPA component - DANIDA project, [13] T.P.H Son, 2010, Applcaton of remote sensng technques for coral mappng n coastal waters of Vetnam seas the scentfc report n the Jont Russan-Vetnamese project of the Insttute of Marne Bology RAS and Insttute of oceanography VAST Bodversty and reproducton ablty n coral ecosystems of Vetnam [14] Vo S. T, The corals at Condao Archpelago (South Vetnam): Before, durng and after the bleachng event n Proceedng 9 th Internatonal Coral Reef Symposum, Bal, Indonesa, vol.2: [15] Vo S. T (Chef author), Nguyen Huy Yet, Nguyen Van Long Coral reefs of Vetnam. Publshng House of Scence and Technques, Ho Ch Mnh Cty. pp 212. Acknowledgments The authors thank Japan Aerospace Exploraton Agency (JAXA) for supportng the ALOS-AVNIR2 satellte mageres under ALOS-PI 326 project; the Unted State Geologcal Survey (USGS) for LandSat ETM + magery and the Natonal Aeronautcs and Space Admnstraton (NASA) for the MODIS mageres whch contrbuted n ths study