Review of Environmental Features of the (sadhotomo, B.)

REVIEW OF ENVIRONMENTAL FEATURES OF THE JAVA SEA

Bambang Sadhotomo')

ABSTRACT

Old information and recent data were synthesized in order to reveal comprenhensrve descriDtion of the environment feature of the Java sea. Descriptive analysis was performed on various foimat of data Physical feature of the Java Sea related to the eastern Indonesian waters and the northern reoion and impacts on the materials input and circulation in the coastal area. Two possible sourcei of variability's affecting lhe characteristics of the Java sea, the first was monsoonal variability and the second was the inter annual ones. Circulation pattern generates a specific stratiflcation of witer masi th-at would be very important for the repartition of the palagic fish concentration ano signiRcanl 6ct,orin affecting migratory scheme of the oceanic pelagic fishes, as we as stratificati;n or ptanitonil abundance and diversity

KEYWORDS: environment, monsoon, migratory, Java Sea

INTRODUCTION MATERIALS AND METHODS The Java is Sea located in the southern most of The data and information used in this studv are southeast and bordered by three islands. from several source and studies document;d in Java in the south. Kahmantan (Boineo) in the north various format of flgure and textual information, as and Sumatera in the west. lt is also connected to well as from observations made durino acoustic the southern by an ouflet. ie. cruise of RA/ Bawal Putih conducted by pelfish , and widely ope'ned to eastern Project in the years 1992 to 19951 and recent through . Thjs condjtion reveals a inhouse project in the year 2004 to 2005, (Figure possibility highly of influence by other ecological 1). Descriptive presentations are performed in area, at least, the northern and eastern areas. figures, charts, graphics and tables. Refigurizing Also, it is well known that the climate over the Java descriptively the text formats are needed governed rn ordel Sea-is by monsoonal variability (Berlage, to clarify and to synthesize the information. 1953; Wyrtki, 1956a; Durand & petjt, j 905).

Many factors involved in the system of the Java RESULTS AND DTSGUSSION Sea may be deducted, but issues on the complexity of the interrelationship between many Morphological Feature of the Java Sea aspects, at least, need a wide range of diclplines and specific works which are bevond the scooe of Toponomy and bathymetry this study. Thus, in the context of this studv. a general knowledge on the functioning of The Java.Sea is part of the which ecosystem ts necessary in understanding the extends from the Peninsula of Indochina and ends pnenomena related to the bioecological aspects, in the continental slope near the l\radura lsland. lt population /.e. change, spatial Oistribution pittern, is some shallow waters with average of 50 m deep response of fishermen to disponibility of fish, as and bordered by three main islands, Sumatera in well as biological and population cnaracrers. the west, Java in the south and ln the north. There are three possible connections Thjs to study is aimed to briefly synthesize and other ecological areas the Southern China Sea compile existing the results of hydrographical waterg, Sulu, and Sea in the north and surveys made during 1900 to 1970 decades and the eastern Indonesian archipelago waters in the recent observations. This study consjsts of two east. In the north west and the northeast it is parts: the physical and biological enviroments. connected with some parts Karimata Strait and have been reviewed exhaustively Strait respectively and in the east it direcfly opens elsewhere (Potier & Boely, 1990; Durand & petii, to Flores Sea. 1995). lt includes an evaluation on climatic variability and its relafion to the hydrographical properties Inside the Java Sea five groups of islands and orographical feature of the spread in this area. group of Bangki and Betitung terrestrial area. In the northwest, Seribu lsland off .

Research lnstitute for Manne Fisheries, Muara BaruaJakarla

129 Ind.Fish Res.J. Vd.12 No.2 Desember-2006: 129-157

o tt

J

Longitude

o at I

Longituds

{ at 5 5

Figure 1. Selected tract used for analYsis'

factor defining structure of bottom part, -Matasiri reoarded as a Karimunjawa in the middle. ::,i:i;Jt-e'iirorst lation of sedimentation in ine e'ast-nortneast and Kangean in southeast' -"u"p"n'oed drifted by rrvers grouP- or ii-it'" """ut'material considering the connecting areas' coastline d,.the Bv sea. i"uor"tting into this area along illt,i*'lJinJ-in the Southern south china rne part or the boftom southern Part of ;;;;i;"s iitanos. l9:t ;;"i;;-bt; lsland in sediment of this area is constituted taken into account' rro.ti"l" il,iaxassar Strait should be ir-"irit-niCn"10 olils formed bv highlv d"lt:,lt* r"u"i.'r" it'" nort[western part' the sea bed rs Sedimentatlon and orography iiiil"a'*iii i."J titeri"t to"o with coral (F'sJre small istands the bottom profile geological nature.of i-t in in" near some The terrestrial and "r"" a mixture or coral' sravel and the island surrounding the Java Sea could oe ;il#i,aie;;.i"i;f

130 Review of Environmental Features of the Java Sea (Sadhotono. B.)

a. ir6 1!.i Source ot datar Losse & Dwiponggo 1977t lB) anet Emety et at. 1972\

Figure 2. Bottom subslrat of the Jeva Sea ((A), shell, debris while parts in some of non muddy be seen ln Figure 2, that sand or sandv substrate suDstrate are frequenfly covered by some specie; tend to be exist closer to the coast kalimantan or c^orat, giant poferlon of sponge. (Saeger el a/., while in the north coast Java, 1976). of fine silt content of sediment ate usually found. More detail observations made in the Java side area indicated . Rough examrnation on type of bottom substrate that highly silt content (more than 7S%) was found by observing soil attached in otterboard durino an at stations located in the north coast of Java (Wlde extensive crurse of RA/ Mutiara 4 (Saeger eial., et a/., 1989). lt is we known that the soit tvDe in 1976: Losse & Dwiponggo. 1977; Dwiionggo & Java is composed by gromosol and latosol tsadruddin. in the 1980) provides an additional high altitude and aluvial soil in the plane area in Inrormatton to the result of previous investigations northern part, whilst in Kalimantan mosfly by silica or Emery et at. (1972). Type of deposited material soil covered with peat on the top layer. rn the s,ea bed indicates a possible similarity with the soit at the river basin areas. The iluvial In the coastal areas surrounding sedrment input from . the Java Sea, the land relates to the nature the phenomena of sedimentation of geological characteristics ind highly input of the superficiai oi of material from the land are apparent. forhation catchment region (Bird, 1979). Or flver delta and natural formation of new coast line would be parallel phenomena wtth the The fluvial sediment input from land . the relates deposition sediment in the sea bed. In certain to the_ nature of geologrcal characteristics of the delta, sedimentation process is considerably high supentctat ot catchment region (Bird, 1979). lt can as shown by their morphological structure, such is

131 tnd.F,sh Res.J Vol.l2 No.2 Desember-2006: 129-157 multi delta and single frnger types of Mahakam and enriched area. lt should be noticed that the Solo deltia, respectively. These types of delta are coverage of the local current would extend to usually constructed by a predominance influence southeinmost of . Horizontal of rivei rather than other factors (Allen efal., 1979). movement of the buoyant material could be said to of nutrient "ariation of the amount of suspended sediment be more dominant than vertical transport and other material input from land link to river debt from the deeper part beyond the slope and erosion level. However, distribution pattern of Unfortunately, .no large scale measurement had precipitation rate, topography (slope of gradient) been made for allowing to figurise the distribution ind vegetation coverage take an important.role of sedimentation level over whole Java Sea determining this variation. In this case' high erosion orocess and fluvial sediment yield in Java Climatic Factol can also be considered as the other example. Monsoon wind For these reasons, the influence of an extensive areas on the variability of coastal area in the north coast The monsoon influences part of Japan The The catchment area of this river from east of to southern - of Java is obvious. ot tne is relatively large and occupied by dense Java Sea, as part of its coverage areas (average) volume is influenQe, its climatic system is completely population.' Also- its which enermous compared with other big qoverned by the monsoonal climate toirsiderablv hydrographic condition in Java and Sumatera (Table 1) as well as a Seasonally ;ffects its rivers (1987); the monsoon coulo oe limited veaetation coverage (forested zone) Followino-as Fieux semi annual reversal of wind and Undoubtly, i consequence of short period of fresh defined a in the coastal current regime. The areas influenced by the- water input and high sedimentaton -could term of gener,ted by this condition Hoekstra monsoon be expressed in area wili be (Pedalabord' amount of sediment atmospheric and oceanic parameters et a/. (1988iestimated that reglme oI dry season (southeast 1970). Bv this definition. the monsoon ro"o trit 56lo River during could be only 10% of total annual *inJ'and'cunent over the Java Sea area tons*nl account for where the million ton. ihis deltaic deposition as monsoonal those, inoui or'tz "oniia"i"a'prevailing wind and current change by ciused to an approximately of 70 m per year or direction of gb, ,.e n;rthwest to southeast direction actual longitudinai growth rate of new coast line' r-ore inan , durino North West Monsoon and the opposlte (Figure 3) Strait' the high dense Jirecfion Ouring Southeast Monsoon .As ln the southern Makassar the- can be regarded as iontequ"n"" of this seasonal changes' mud laver near the della area changes. of of suspended material input ;;;d; clearly impact a Periodical i iJsuri of deposition paiameters in ihe Java Sea During River and qontinuos direction of rrom lrtanafain "ito.ptt"tic (November to February) the (north south direction) in the strait The north west monsoon cuirent from the northwest to the the part of shallow area would create oievairino winos comd iircutatron in from the Indian ' a specific circulation which spreading the ioutheaslt with the humid air susoinded material coming with fresh water' From June to September, during the southeast wind blows ftom the soumeast A hyphothetic lo€l current propose! by Allen et monsoon, the dry air from region The intensity at. $iis) can be used to predict distribution of bringing big river in Java and sumatera (Badan Pusat Table 1 . catchment area and volume of selected Statistik, 1994)

Sumatra: Java 0.5 0.5 Batang Rokan 4.8 4.1 Cimanuk 1.6 1.6 Batang Kampar 4.0 ,.o Ciu.iung tE 0.5 't.3 Kampar Kiri 3.4 Ciwulan no Kanan 5.2 J./ Kali Bodri 0.6 Kampar z.o Kampar Tengah 1.7 8.0 Kali 3.1 2.O '1.2 Batang Tembesi tq 4.0 Kali Lusi 1.9 17 .8 Kali Lukito 0.3 Batang Hari za.z Way Semangka 1.4 2.0 Kali Solo 37.0 Kali 4 9.5

132 Revi?w of Environmental Features of the Java Sea (Sadhotomo, B.)

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Figure 3. Monsoon wind direction during January and July (Fieux, 19gZ).

are more regular but the maximum wind force to be demonstrated by Potier & Boety (1990) based on less than the previous one. Based on the record of commercial vessel ship passing this meteorological statton in Jakarta harbour, a maximum of wind velocity was 35 knot during December to January, (\ /yrtki, 19S6b) but in othe-r Current Regime report, the maximum one at sea can attain 7,2 m per second in August (\ /yrtki, 1957), but in other In the Java sea, term, . the currents are generally ruled the worst weather condition was in by the monsoon and their djrectionttend to follow December with the sea state to be around 4 to 5 of the prevailing wind which gradually change all of Beaufort scale as reported in the captain bridge the year with reversal during periods of record June to chit of the demersal research vessel August and December to February. However, this Mutiara 4 (Losse & Dwiponggo, 1972). Owing to cycte generates a structure of water mass and its tne trequency of occurrence of its directions, the consequences through water mass exchange component with of east and southeast wind durlno other areas. The change of salinity should be southeast monsoon greater is than the west and sought as an indicator of this process. These northwest ones during opposite season (Figure 4). phenomena have been described (Veen, 1903; uunng rntermonson (Nlarch to May and October to Wyrtki, 1957; 1961) and some review in November), wind direction seem to be more varv conjunction with lishing system have been as indicated by local wind blows from and to th6 presented elsewhere (Potier & Boely, 19gO; land. lt seems that local winds produced by the Durand & Petit. 1995). difference air pressure of above the sea and the land, sometime is more important than the In general, the wind driven currents iust reflect petit monsoonat one, As stated by Durand & the movement of surface or near surface water (1995) that land play jmportant wind can an role in mass, but due to the depth of the Java Sea a regulating the current during inter monsoon and possible vertical mixing west is obvious though the monsoon. A similar figure has been coriolis effect could be ignored because of low

Jrva Sea 1000 ENo-

7 5'/o E St,7 aNw 5070 gw

@ sA-E 25y. !s

oah Jan Feb Apr May Jun Jut AuS Sep Oct Nov Figure 4. Composition of wind direction in the Java Sea and Southern South China Sea. Source of data: saeger et ai, 1976; Losse & Dwiponggo, f sZi; D"e;lgg" & 8adruddin,1980

IJJ lnd.Fish Res,J. Vol.12 No.2 DesembeF2006: 129-157 latitude position of the Java Sea. However, the the sea bed and the occurrence others deeper horizontal currents engender a gradual shifting of passages allowing water exchange between water mass from eastern part during the Southeast Pacific and , is through Lombok monsoon (July to October) and from the north and Strait, Banda, and , it is less possibility west during North West monsoon (December of direct interconnection between Java Sea and i,4arch). those . But, due to its location, in lower scale, the Java Sea could be sought as the main The water exchange through the Flores Sea passage of the water flow from and to the Flores during the Southeast monsoon and Karimata Strait Sea and the South China Sea. Vvhile, a connection during North West monsoon respectively can be with the Indian Ocean is probably exist through regarded as important factor determining seasonal in low intensity. change of hydrographical characteristica of the Java Sea. Seasonal movement of the water mass Refer to the results of previous works (Vwtki' will raise an ecological issue about its relatlon to 1957; 1961), trend of the current direction in the eastern part of lndonesian archipelago and the Java Sea can be clearly described as in Figure 5. Southern China Sea. In other side, the eastern At the beginning of the southeast monsoon on Indonesian waters, the and part of the June the current comes from the east, bringing a Flores Sea are well known as a gate of the higher salinity wate6 mass from the Flores and throughffow between the Pacific to the Indian Binda Sea as well as from the Makassar Strait' Ocean (Molcard el al., 1995). Refer to bathymetry but the penetration of high salinity water does not chart, three passage would play an important role reach yet the middle of the Java Sea (detail of in large scale circulation between the two oceans explanition is presented in the next chapter). the Lombbk Strait, (between Bali and Lombok lslands), Driring this period, the sea ftont clearly showed Banda Sea and Timor Sea (Timor Passage). As directlon of this current (Emery et al.' 1972\. shown in current chart of Wrtki (1957) (Figure 5)' the currents flow from to Indian The resultant of current will not change until Ocean pass these passages during southeast September while the strongest velocity occurs In monsoon (June to August), while during northwest Aubust. In October, a weak current still enters the lhe monsoon inverse movement of water mass Jav'a Sea from the east, with the resultant of the of in lower intensity. lt can be noticed that the direction in the northern part' in the south acts begin to tendency of the throughflow would be from Pacific Kalimantan Coast, while a west current passing the to Indian Ocean. So, by considering the depth of enter weakly from Karimala Strait

:'/ ,ll t'f'S

134 Review of Environmental Features of the Java Sea (Saclhotomo, B.)

.'"(i \z!-- -

J a-1*\

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- - - -> 12 crn/s.c 50 o/..c + ------> 25 crn/s.. , -+. ! 36d E€c r'.+

Figure 5. Surface currents around Indonesian waters Wyrtki, 1957).

135 /nd.Fish Res.J, Vol.12 No.2 Desember-2006 129-157

southern part of the Java Sea. During periods of derived from these sort of stations as conducted by inter-monsoon (October to November), 2 directions Wyrtki (1956). The sea rainfall should not be of currents exist in the Java Sea, the shifting of sought as the main faclor in desalinisation of sea water mass change gradually. On December' water, since run off and river discharge also current direction completely inverses, and this contribute to this process. Distribution of direction will be maintained until March to April On precipitation profile over the mainland surrounding April to May, that is under period of second inter the Java Sea would give influence on seasonai river monsoon, 2 opposite direction of current will occur variation of dilution of the coastal water by the as the first one. During the inter monsoon the disch a rge. direction of wind and current frequently change fluctuation of precipitation irregu larly. In this case, monthly rate in the catchment areas directly relates to the During the ralny Rainfall variation of river discharge debi. season, a heavy precipitation will be immediately Generally, over almost part of the land followed by an increase of fresh water discharge of By taking surrounding the Java Sea, rainy season occurs the rivers flow from the main island during North West monsoon, lasts from Negara and Amandit River (as part of Barito River the maln December to February with its peak in January, in ) for representing the the discharge w tl- while dry season lasts from July to October during one, a coincidence fluctuation of to be Southeast monsoon and attaining its minimum rate rainfall over the catchment area seem pattern ol on August or September. The relative humidity obvious (Table 2). However, distribution ln Java reache! its maximum value at 89% on December the rainfall is not same to each area. vary than those In ano January, and the minimum one observed on monthly fluctuation usually more August at 77%. in the mainland these atmospnenc Kalimantan and Sumatera. parameters behave in the same fashion. By referring to zonation of precipitation prof le (Huke 1982) it is lends to follow a cycle of or aqroclimate chart (Figure 6) Precipitation usually in the wind regime and atmospheric seasonal cleai that the length of dry season the upstream areas of big river in Java Rain-fall over the sea areas usually to be, catchment and chanqes. (such river) is absolutely longer than ln assuired to have similar behaviour with those of as Solo Sumatera. Also shown in Table 2, lsland areas. No direct observatlon kalimantan and the coastal and stations in the north coast of Java have been done for sea areas, but an estimation at three

stalions in Kalimantan' Sumatera Java and over Table 2. Averaqe of precipitation rate of several -t", ,ti"t and river discharge of two rivers in Kalimantan un Ju mm) 125 167 o9 81 192 zoo Banjarmasin 403 359 336 270 299 173 153 . 129 90 120 189 z5Y M. Pudak 303 243 275 216 184 358 468 271 Pontianak 270 117 301 317 314 358 144 203 153 182 130 2?7 388 Ulin 399 341 370 264 163 159 108 110 136 216 zta Samarinda 189 161 183 189 244 172 209 ZJJ 288 224 223 128 149 222 258 284 275 Pekan Baru 255 170 228 333 167 98 88 110 145 226 221 Jambi 233 286 39'1 258 153 124 129 72 78 58 76 126 Jakarla 304 515 406 300 100 150 90 87 ,J9 Yf, 154 173 234 ,-, 388 27O 227 118 68 97 38 77 126 Rainfall over sea areas '"'(mm) 93 56 46 96 151 257 Java Sea 288 219 202 166 177 127 69 zo 52 126 240 Flores Sea 274 193 195 188 176 137 142 139 '188 , 338 South China Sea 287 162 176 176 183 166 Discharge debl (mr Per sec) 12 19 39 Amandit river \') 41 44 3E 40 36 27 18 12 50 33._ 36 88 164 river(2) 203 192 174 182 151 117 95 otherwrse on 1980 lo (Source Agency and

,,,= ;:::11"1?#,[1laa)ata or rszz to i987 (source: Drrecrorate cenerar water Resource and Deveropement-JlcA years 1956) 13331on fiom several ioastal and island stations over 2710 35 0'A/yrtk '''= "" "*,"ged

tJo Review of Environmental Features of the Java Sea (Sadhotomo, B.)

'9 t.9 t6 g

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Figure 6. Distribution of duration dry and wet season as described as number months precipitation of with ress than 100 mm for dry season and more than 200 mm for wel season (Huke, '1982).

(Jakarta, Semarang, and Surabaya), the length of Southeast monsoon droughts in Java with these perjod that the precipitation rates less than 100 mm rs events estimated to be 93%0, while 78yo of El Nino 4 to 5 months, while in Sumatera, events can be associated Kalimantan, and with east monsoon South China Sea, the duration oi drought (Quinn et at.,1978\. the dry season usually less than 2 months. Hence, 0rnerent seasonal variatjon of the prectpitatton over In term hydrologic the,three of parameter ln the Java main lands clearly resuli different pattern sea,^ the rmpact oT of EI Nlio_Southern Oscillation, the debt of river discharge and intensity of can be hypothesised jncrease ortutron process as the of salinity as in the coastal areas. The longer caused by longer dry season a stay of the oceanic water in central and and less penetrating this area. amount of river dtscharge generate a different pattern of dilution along north coast of Java. In order to detect an jnterannual variability of the rainfall pattern Interannual Factor in relation to global chang6 of atmospheric fiuctuation, serial data of precipiilation from certain stations in Kalimantan, Javb, and A coherent of global pattern of oceanlc and atmospheric Sumatera are examined (Figure 7), as well as the fluctuation, so called, Southern anomaty (southern Oscillation would give important Index oscjjlation index) an impact on expressed in crrmatrc vaflation. as well different air pressure between Tahjtj as hydrologic one. This and Darwin (Figure anomaty occurs cojncidentally 8). These figures clearly Show with major change tnat a low precjprtation In current and temperature rate of at 2 stations of in the eastern Kalrmantan in 1983. at equatorial Pacific, which is so called Jambi in 19g9 as well as a El Nino. Then, high rate in 19gg the two phenomena refer to join y to 1989 in Kaiimantan can be as El Nrrio_ regarded as an anomaly Southern Oscitlation. The influence which associated wjth El of El Nino_ Niio-Southern Oscillation. In Southern Oscillation on South East Asia has the year 19g3 the not impact of a longer dry season yet been comprehensively (Nicholls, in kalimantan on - mapped nver otscJtarge was 1993). In term of climatic parameters, clear,y indicated by low debt of it could be r\egara F(rver. In the southern part shown by dislocatjon of ralnfall in some areas. of Kalimantan (Figure 9). lt means that dilution process Anomalously heavy precipitation in the central and in the coastal area in whole Java Sea western equatorial Pacific and Indonesian drouohi durjng that period -on would be lower than those of normallears. are associated with El Nlno rype event. Based Also, high rate of precip jtation in 19g9 1'16 years of historical data, the assocjation of whlch was an unusuat ratn pattern in Java indicatinq an

137 lnd.Fish Res.J. Vol.12 No.2 Desember-2006: 129-157

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0 ,1974 1990 199 11970 1971 1972 1073 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989

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500

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1984 1984 Evolution of monthly precipitation rate at various stations in Java, Kalimantan and Sumatta. Remarks:x's indicate yearly average Sourc6: Agencl of Meteorology and Geophysics, BMG, Jakarta

association or indirect relation with the phenomena for the three island, but trend of the rainfall of El Nirio type event (Quinn et a/., 1978; Karmini oscillation in Java and Kalimantan potentially er a/., 1995). At the same period, in Jambi, the behave similar fashion. rainfall showed a different tendency, the precipitaiion rate was considerably very low. In Hydrology norlh coast of Java, as represented by the average of three statjons in Jakarta, Semarang and Salinity and horizontal circulation Surabaya. a high precipitation rate in 1981 to 1982 tended to be more obvious than in the periods of The surface current regime as described by 1988 to 1989, and low rate in 1983 seemed to be a Wrtki (1957i 1961) would reveal many normal rather than an extreme value in drought possibilities of a mixing process and the influences period. These patterns do not give a similar ligure of other waters areas on the characteristics of the

138 Review of Environmental Features of the Java Sea (Sadhotono, B.)

2.0

o--- nn

4.0 1970 71 73 74 76 77 79 ffi 82 83 85 86 88 89 91 s2 94 95 Figure 8. Southern Oscillation Index observed during last three decades. Sourcc: http:rv/ww.nodc, NOA. gov

^ J00 ! zso E 3 20o $ iso 5 roo

1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 YEA RS Figu re 9. Evolution of river discharge of Negara River (a lributary of Banto River) South Kalimantan. Source: Dir. G9n. Waler Resources Dev.-JlCA. 198E

Java Sea waters. At least 2 sources of sea water Until now, the knowledge of 2 dimensional masses entering the Java Sea can be defined: one distribution of the mixed water is unclear, and there is the origin of Southern China Sea by passing is no fixed border horizontally defining the type of Karimata Strait and another one coming from the water. In this chapter, general explanations Pacific through Flores Sea and Makassar Strait. are given and based on the progression of the Also, desalinisation following an input of high debt more dominant water penetrating the other type of of fresh water discharge creates another type of a water detected from the movement of certain seasonal mixing process in the near coastial areas. arbitrary isohaline, i.e. 32 and 34'i6! isohaline for These water masses exchange and circulation are the type af coastal and of oceanic water mostly governed by monsoonal system exerting respectively. Owing to the previous works (Vwrtki, through the seasonal change of atmospheric and 1956; 1961; US Navy, 1987), charts of surface current regimes. salinity were redrawn with trivial modification and without changing general pattern. In this case, Wrtki (1956) classified the water circulating in periodically shifting of isohaline characterising the the Java Sea into three distinguishable types. The water type origin are used to demonstrate the first one is the oceanic water with saliniv more changes of surface salinity in relation with the than 3496.. The second one is mixed water with its water exchange and the mixing process (Figure salinity range 32 to 34%o and contributing more 10). than 60% of the total water mass circulating in this area. lt originally comes from Southern part of During the Southeast monsoon, the prevailing China Sea and mixed with fresh water inside the wind and current come from the east and at the Java Sea. And the third, is the coastal water with same time, the oceanic water enters the Java Sea salinity to be less than 32960. lt has the same orioin and gradually pushes the lower salinity water to the as the mixed type but it has undergoie west. On June, at beginning of this season, taking desalinisation along the coast 6f east Sumatera place in the eastern part of the Java Sea, the and Kalimantan during the passage to the Java oceanic water starts to move to the west northwest Sea. Another type would be river water with salinity direction and begin to push the lower saline water to be less than 30%0. to the west. This type of water has not arrived yet

139 tnd.Fish Res.J. Vol.12 No.2 Desember-2006: 129-1 57

Figure 10. Surface salinity of the Java Sea and adjacent waters (adapted from: US Navy' 1987; vwrrki,1956; 1961).

the middle of the Java Sea but isohaline of 32%o with an oDDosite direction. lt means that the mixed has reached around Bawean lsland. The farthest water mass from the Southern South China Sea penetration of the oceanic water occurs in shifis to southeast following the direction of the September to October when the tip of the tongue current and begins to occupy the southern part of of 34960 isohaline reaches the middle part of the this area (Figure 5). The salinity in the western pan Java Sea and during this period the range of will decrease as the mixing of the 2 type of water observed salinity's values to be 32.5 to 34.25%0. lt undergoing. On December, this process wlll be takes approximately 'l or 2 months of lack time more intensive. A stronger current bringing the between the peak of southeast monsoon wind in water mass from the northern reglon starts to August and periods for reaching the western part. replace the oceanic water occupying from the previous season. In this period, salinity's values in On the contrary, at the end of Southeast the middle oart of the Java Sea are in the range of monsoon on October to November, the direction of 32.0 to 32.5%o and tend to be lower in February to the east current tends to bend northward while in N4arch (31.0 to 32.001,!) with the minrmum values the southern part a weak current begins to flow obseNed is located in the western pan.

140 Review ol Environmental Features of the Java Sea (Sadhotomo, B.)

In term of west east axis and periodical scale, a than off south of Kalimantan, as well as in progression of the surface salinity has clearly horizontal direction. The salinity profile as depicted shown a general change of the salinity. A more in Figure 12 in the south section, are attributed to detail salinity contour in the middle area may be the outcome of 2 factors, the invasion of figurised using intensive observations made during southeastgoing current from the northwestern area the cruise of RA/. Bawal Putih in October 1993, pushing weakly the most stagnant oceanic water February 1994, and Sepetember to December and the contribution of fresh water discharge. 2005 (Figure 11). As shown in the figure, during October cruise, the water circulation would create ln.February, stratification of the vertical water a specific water mixing beginning from the middle layer could be said as an opposlte of the flrst one. of the Java sea, off the north coast of . The strata of vertical layer are clearer and more On October, a current flows weakly from northwest significant in the middle and north sections. Some region 0.o. Southern South Cina Sea) then turn to fresh water mass originating from river discharge in the east direction as its velocity slowing down as the south of Kalimantan greatly impact a vertical far as Bawean lsland. However, this current is change of salinity in the north section. While in the considerably very weak but it can slightly push part south section in the eastern part of the Java Sea, of water mass body in longitudinal direction, at the the existing of lower salinity in the near surface same time, fresh water discharge from land gives layer maybe caused by same process. ln the additional contribution to lower the salinity in the southwest-northeast direction, the horizontal coaslal area of the southern part. However, salinity gradient is more important than the vertical stronger easterly current is still flowing from one. Nevertheless, the saline water mass tends to eastern region in middle part of the Java Sea as occupies the lowest depth layer in the south and shown in the Figure 5. This scheme would middle areas. lt means that the oceanic water continue until the inter monsoon oeriod then mass still occupying the Java Sea at least, from reverse again with reentering the oceanic water to the near bo$om layer in the longitude 109 to this area during the Southeast monsoon period, nearer surface as it aoDroach the Flores Sea as from June to October. confirmed by salinity profile of F3 and FO selected stations (Figure 13). Vertical Circulation . Another possibility is the occurrence of a sub In fact, there is few information on the vertical current from the east while thg surface one being shape of salinity profile in the Java Sea. The most weakened in October. This under water current wlll detailed observation of the previous investigations be more important in the south section on Febrlary concerned with limited area, e.g. the cruise of RA/ as shown by the thickness of the layer (Figure '14). Samudera in the south coast of Kalimantan as The horizontal salinity contours drawn for 2 to 10 m reported rn the Oceanographical List attached in and 20 to 30 m deep layers respectively in journal of the Marine Research in February and October (Figure 15) do not (Soeriaatmadja, 1956; Sjarif, 1959), and the cruise signrficantly illustrate a clear vertival stratification, of RN Coriolis during Pechindon trip in the middle even though the tendency oi occurrence of higher part of the Java Sea in 1985 (Boely et a/., 1986). salinity in the deeper layer in eastern part ls An attempt to expose a preliminary result of the apparent. Unfortunately, there is no complete cruise of RA/ Bawal Putih in the larger scale area information or observation made tor confirming the has been well documented (Durand & Petit, 1995). phenomena of underwater circulation and water In order to allow a comparison between sections, mixing in the inner layer of the Java Sea. lt means several tracks of salinity observation stations are that the oceanic water mass still occupying the arbitrarily rede{ined (Figure 11). Reanalysis of the Java Sea at least, from the near bottom layer in the same data of the cruise (ie. cruise in October longitude '109'C to nearer surface as it approach 1993, in February 1994 and September to lhe Flores Sea as confirmed by salinity profile of December 2005) are presented in Figure 12 to 14. F3 and F6 selected stations (Figure 13). Another possibility is the occurrence of a sub current from ln October, vertical mixing in some part of the the east while the surface one being weakened in Java Sea are evident in certain level of depth with October. This under water current will be more different fashion. In the area off south coast of important in the south sectioh on February as Kalimantan vertical mixing is a typical of dilution shown by the thickness of the layer (Figure '14). process which gradually taking place near the coast area the lower saline water (less than 32%d Temperature tend to occupy near surface layer until 25 m deep' especially in the areas between 115 to 116 E and As other tropical waters, the fluctuation of the 109 to 112, whilst in the area off north coast of surface or near surface temperature are relatively Java, the vertical mixing seem to be more intensive very small. Refer to the previous investigation and

't41 /ndFish Res.J. Vol.12 No.2 Desember-2006: 129-157

J. =June 1992 O.'Oclober 1993

Lo.situd. (9 Figure 1 1 , Position of selected CTD'S stations used for defining sections zon9s of Figure 14 reports (Saeger et a/., 1976i \^/yrtki, 1957) the ln general, the influence of rain fall on the differences between the maximum and minimum temperature of the near coast line waters would be values in the Java sea are less than 2'c with the significant as it was noted by Durand & Petit average value in the range of 27 to 29'c. (1995), while in the larger area, the gradient of the temperature are caused by the different origin of Horizontal distribution of surface temperature water mass which seasonally invades the Java are usually attributed to the seasonal phenomena. Sea. As illustrated in the temDerature contour

142 Review of Environmental Features of the Java Sea (Sadhotono, 8.)

October 1993 (Cruise 34) Nonh S.ction (%.1 k" n"' H"- tr:.

i

1@" alO" L't. 112" 113. t1a. 116. 1t€.E

February 1994 (Cruise 41) North S.ction Mlddl. S.cti.n (%")

10 10

m & e 1 iro & a60I g! 50 70

,112' 1€' 'f to' 111' 't't3' 1L' 115' E

Soutltlert florih.an S.cricn Soulh Sectlon

10 tu

30 s40 o50t

60

70

110', 1'|1', 112' 113' 114. 1t5' E

Figure 12. Salinity profile in certain sections during Cruises of RN Bawal Putih in February 1994 and October 1993.

143 lnd.FEh Res.J. Vol.12 No.2 Desember-2006: 129-157

June

trll c E :1- ;F " t- e "1- € ',r I "f I ::T

February

i

October e' -1t_T

'1-- + . f- tt I TD !t -= Figure 13. Salinity by depth of selected stations.

144 Review of Environmental Features of the Java Sea (Sadhotomo, B )

Longitudinal dir./ Central Java /0ec.2005 psu L ongitud in al dir./ CanlrdlJava -Flores/Oct.2005 psu

E

110'

Lo ngitudina I dlr,/Karim unjawa.M atasid Bank/Feb.199 4 L ong nud in al dir./Ka rim unhwa-Matasiri Ban k/O ct.19 93

E E

SEA BED

112' 113" 1,11' 1t5. Long itu de Longitude (deg.E) Transv€raa I lJava/Sept.200 5 Tra nsve tsal direcfb n/Ce rnral Ja va /Dec.20 05

E -20

-30

3.5' 4.0' 4.5' 5.0" 5.5. -S.9. _6.4" _S.9. Latitude (S) Laritude tS) Figure 14. comparison of salinity profire from differerent periods of observations,

145 lnd.Fish Res.J. Vol.12 No.2 Desember-2006: 129-157

a, February Depth layer: 2 to 10 m

Depth layer: 20 to 30 m

b. October

Depth layer: 20 to 30 m

Figure 15. Distribution of isohaline in various layers.

146 Review of Environmental Features of the Java Sea (Sadhotomo, B ) drawn from the observations made during October discharge. While in the offshore area, between and February cruises, a slight gradient were Madura lsland and Kalimantan, and off Jakarta, observed in southern and northern legs of the the water was clearer than those of coastal areas. areas covered (Figure 16). The water transpar.ancy in thts sub areas would During the northwest monsoon (February), the attain the maximum values on October. Based on highest temperature tends to be found in the the pattern of tranparancy contour lines, there are northeast, on the contrary this gradient was three possible factors controlling the transparancy reversed during the Southeast monsoon as il in the Java Sea. The first, are deposite, observed on October. Refer to the Drevious suspended, and buoyant materials brought by river explanations these gradients should be attributed discharge. The second one would be the depth to the invasion of west going and east going and current. The current passing shallow area currents. In this case, the higher salinity's water would be able to generate a turbulence in the near coming with east current from Flores Sea during bottom layer and raise the deposite material in the the Southeast monsoon has a slightly lower sea bed. As mentioned above, the clear water in temperature compared to lower salinily's water Southem South China Sea would be caused by mass from the northern and southem parts. low speed northwesterly current during the beginning of Southeast monsoon. The third one, is The higher temperature of the coastal water water mixing with clearer water water mass coming mass can be sought as an outcome of a mixing from Indian Ocean and Flores Sea. with the fresh water. Hence, the fresh water runotf and disharge must be warmer than those of sea The optimistic values given by him showed that water. A comoarison between temoerature the nikate concentration in the surface layer were gradient of surface and 20 to 30 m deep layer do estimated to be in the range of 0.2 to 0,6 pgAJl with not give any difference, although the deeper layer the maximum value to be 3.5 pgA/l in the near having a little bit lower figure. coast line of Kalimantan (llahude ,1979). These values are considerable high comparing with the Turbldity values observed in the southern oart of Makassar strait waters as reported by same author (llahude, Generally, turbidity or transparancy relates to 1978). But, during the cruise of Pechindon in May . .debris concentration of solid content, buoyant 1985 (Boely ef a/., 1986) never found any particles or suspended and density of significant concentration of those nutrient. microorganism in the sea water. In ecological sense, the turbidity of sea water would be more important for pelagic fishes than demersal one. Primary Productivity Unfortunately, no relevant information concerning to pelagic species had been published. An extensive survey had been made during east monsoon (September to October 1964) and An attempt to figurise the distribution of Intermonsoon (March to April 1965) covering the transparancy of the coastal areas of the Java Sea Java Sea, Bali and Sunda Strait, and Indian is presented here, using the sechi disk reading Ocean. The results gave an indication of a high data made during the cruises of RAr' Mutiara 4 in rate of surface productivity in the nearer stations to the years 1978 to 1979 as listed in the report of the coastal arca and the island. The highest figure Beck & Sudrajat ('1979); Dwiponggo & Badruddin of all areas was 39.11 mg C.houa'.m-'. located off (1980). Tranparancy measurements were done by the estuarine area of Barito River, The average observing the minimum depth of invisible of 30 cm value was around half of the maximum one. and diameter of white disk shinked in the water. As the minimum was O.O5 mg C.houi1.m3 (Soegiarto shown in Figure 17, the tendency of transparancy & Nontji, 1966). These results were slightly higher in the coastal areas seems to be seasonal and than those of Doty 6f a/. (1963). lt could be noticed their gradients tend to follow the isodepth or be that no significantly different between the values of parallel with coast line, as shown by the pattern of surface productivity of the near shoreline area of sechi disk contour line. In the Southern South the Java Sea and Indian Ocean. A tendencv of China Sea, on July, the water was relatively clearer higher rate of production frorir western to-the than those of south @ast of Kalimantan and east eastern part of the Java Sea was obvious as well coast of Sumatera during period of July to as of those of the location being closer to the September and July respectively. In the north shore. From south of Karimunjawa lsland the figure coast of Java, during the peak of northwest tended to inclease as the stations moving monsoon (January to February), the water was eastward. Also, the surface productivity of the Java turbid, and an be regarded as being Influenced by Sea in southeast monsoon is hioher than other high suspended sediment load transported by river season (Figure 19).

147 lnd.Fish Res.J. Vol.12 No.2 Desembet'2o06: 129-157

a, October or Deoth

\\ o ------.-\\ ,H,( ... /-; f /J$)aY \s"" cz

Longitude ('E) b. October or Depth layer: 20 to 30 m

fio 112 Longitude ('E) er: 20 to 30 n

r 5

112 114 116 Longitude ('E)

Figure 16. Temperature contour by 2 depth layers observed during acoustic cruises.

148 Reviaw of Environnental Features of the Java Sea (Sadhotomo, B.)

t o lo ocr.zi -io"'

Figure 17. Transparancy distribution of various periods as indicated by sechi disk reading conlour. Sourco: Beck & Sudrajat, 1979; Driponggo & Badruddin, 1980

Oxygen Content layer and by llahude (1979) who gave the range of dissolved oxygen at the surface layer to be 4.1 to Detail observations were performed in the 4.5 ml l-r in the area of southern part of South Pechindon trip covering the sub area from South China Sea waters. All these figures would reveal a Makassar strait to the north coast of Java as far as conclusion that whole water mass in the Java Sea to the depth of 20 m. The results showed that seems to be well aerated. dissolved oxygen gontent was 4 ml l'' in the near bottom and 5 ml l'' in the surface layer. A similar Nutrient result was also reported by Doty et a/. ( 1963) from the survey conducted in Janu?ry 1956 which found Following the previous investigations, at least the value of 4.5 to 4.7 ml l-' in the near bottom three sort of nulrient, phosphate (PO1), nitrate

149 lnd.Fish Res.J. Vol.12 No.2 D$ember-2006: 129-157

a Decemberto May

b June-Noveniber

Figure 19. Primary productivity in the Java and adjacent waters durlng two periods (Soegiarto and Birowo, 1975)

(NO3) and nitrite (NOt had been observed. chlorophyll in the Java Sea as cited by Nontji Deismaii (1939) noted that phosphate content (1977). The values of chlorophyll observed from observed in April and October was not significantly the 2 cruises made during the periods of different, but this value increased slightly as the September to October 1964 and March to^April station to be closer to the coast of Java and 1965 were almost the same, Le. 0,18 mg m-" and Kalimantan. In the area of Southern China Sea. 0.'19 mg m'" respectively. The zonation of around the equator, llahude (1979) noted that the distribution of the chlorophyll-a in the central part of surface concentration of phosphate varied the Java Sea tended to concentrate in the near between 0.1 to 0.3 pg A"/1, and it was relatively coast of south Kalimantan (Figure 20). This higher during the southeast monsoon than phenomenon may be in accordance with another observed values in December, during the observation using Seawif image (Figure 21), even northwest monsoon. though the high concentration of chlorophyl frequently consisted of solid debris and tiny particle Chlorophyl and Plankton of sediment generated by a mixing of fresh water and turbulence. Stratification in the neritic area This part is based on the same source of probably generated the different level of planktonic reports as previous sub chapters. Doty et al. diversity (Table 3). In the near coast of central (1963) gave an argumentation of the tand mass Java, low diversity of zooplankton may be caused effects on the distribution of primary productivity by infertility of the water, as well as of lower fishery that revealed the same impact on the distribution of produclifity of this area.

150 Review of Environmental Features of the Java Sea (Sadhotomo, B.) a. September lo October 1964 .7

b. March to April 1965 -7

Figure 20. Chlorophyl-a distribution showing the density of higherthan 0.2 mg m-3 during September to Odober '1964 and March to April 1 965 (Nontji, 1974

SeDtember to November December to February 2.O 1.E 1.5 1.3 't. o o.a o.5

o.o

Figure 21. Distribution of chlorophyl a as shown by SEAWIFF image observed in the year 2002.

151 lnd-Fish Res.J. Vol.12 No.2 Desember-2006: 129-157

Tabel 3. Zooplankton Composistion sampled in the Java Sea

East of Locality BeritunsJava Madura- North Coast of LamDun ::lL9:1 Mandallka Central Java Taxa/pEriods Sep-05 Sep-05 Sep-05 Oct-o5 Dec-05 Trochophora sp. 0.0 48.3 0.0 0,0 0.2 ylslopsis Ira sp. 0.0 0.0 0.0 0.0 0.3 Acaftia sp. '1016.7 1060.1 438.1 353.3 34.9 Balanus sp. 0.0 8.3 0.0 0.0 0.0 Calanopia sp. 1 1.0 0.0 0.0 0.0 0.0 Calanus sp. 892.0 I ZJ.O 195.0 171.8 Y.Z Corycaeus sp. 204.9 14.7 93.9 4.9 Evadne sg. 92.7 45.8 /J.V 40.9 4,1 Lucifer sp. 6.4 12.8 0.0 2.7 0.8 Microsetella sp. 14.5 31.4 14,7 41 .2 0.0 Mysrb sp. 28.0 JC. / 0.0 0.0 0.4 Naupltrrs sp. 47 .9 't25.7 22.1 26.1 ,l? la2 a Oithona sp. 145.8 I Z.U 124.1 5.0 Oncasa sp. 271.6 321.3 166.4 70.8 5.2 Paracyclopina sp. 0.0 o./ 0.0 0.0 0,0 Penilia sp. 0.0 0.0 2.3 0.0 Pontella sp. co. / 18.3 1 1.0 7.2 0.8 Zoea 77 .0 65.1 30.7 4.5 4.9 Bipinaria sp. o.o 0.0 0.0 0.0 0.0 Saglfta sp. 414.4 '186.I 92.1 t.tz..t Solmundella sp. 0.0 0.0 0.0 0.0 0.7 DiphyeE sp. 0.0 0.0 0.0 2.7 0.0 ,lt 2 Anadara sp. 0.0 1 1.0 2.3 3.3 Atlanta sp. 89.5 4.9 0.0 c.c Limacina sp. oJz.o oc.:, 0.0 19.8 3.8 Oikopleura sp. 31.0 0.0 5.4 13.4 LaNa of Cyphonautes 5.4 0.0 0.0 0.0 0,0 Yenerupsis sp. 10.7 0.0 273.1 0.0 0.0 0.0 0.0 0.0 Total 4057.4 3078.2 1415.0

In the southern South China Sea, the horizontal benthic community and pelagic fishes. distribution of Chlorophyl-a in showed a strong Nevertheless, in certain level, benthic organism seasonal variation. The values in December 1971 Iiving in the sea bed can serve as lower chain in and July '1973 and 1973 were in the ranges of 0.1 trophic level of pelagic fish. The most detailed to 0.3 mg m'' and 0.2 to 0.6 mg m-' respectively. A study ever done was a study on benthic system of comparison between the values of phytoplankton the coastal area of the Java Sea conducted bv and chlorophyll-a in the southern of Makassar Indonesian Dutch Senellius ll Expedition in Jul! Strait and in the southern South China Sea as 1984 (Kastoro ef at, 1989; Wtde sf a/., 1989). i reported by the same author (llahude, 1978;1979) covered the area from the north coast of west Jiva showed that in the two sub areas the densitv of to the north coast of Lombok lsland in the Folres phytoplankton seemed to be similar figure. Bui, in Sea. A total of 373 macro and micro benthic taxa the southern South China Sea the input of material were identified which can be divided into' 2 from the river discharge is more important and taxonomic groups, major taxa ?nd miscellaneous could be regarded as the main factor giving an or lower taxa. Other observation from Southern impact on the higher concentration of productivity. China Sea in the same season (Saeger ef a/., 1976) provides information (iable this ' 4). Benthic community Refigurizing the data of Wtde et af (19S9) by regouping the stations by sub area and comparing Study on benthic ecosystem in lhe Java Sea tne structure of taxonomic groups reveal a are very rare, and only carried out in certain limited significant difference on the benthic communiV area. lt is difiicult to depict directly the link between structure between subarea (Figure 22).

152 Review ot Environmental Features of the Java Sea (Sadhotono, B.)

Table 4. Benthos comoosition taken from various sub areas Nonl;:?it Noff:dcuo;?lor coJt:l:Trtar s:t3?ln raxonomic s'oues or Madura strar')

Crustacoa 120 248 85 162 500 Mollusca 34 39 79 nd Echinodermata 52 27 13 1 nd Sipunculoidea 27 13 18 22 nd Miscellaneous 35 15 24 41 nd Coelententa 211 4 94nd Pisces 45 2 3 12 nd I

I::: t,.

l-l a tt Et ll E m :ilI..', f t,. I

Figure 22. Density of benthic by laxonomic groups and sub areas. Sourcei wilde et al, 1989

In term of evenness, certain taxonomic aroup coelenterata would be important taxonomic group tended to dominate the community, but since the characterising the benthic community in the north size average to be highly vary among the sub coast of Java and Madura. But seasonal area, this figure was not in accord with the fluctuatjon of these figures would be more biomassa criteria. However, the dominance of the interesting, particularly in relation with seaonal taxonomic group can be defined,using criteria of variability in the coastal area. In term of diversity, biomass (in weight), in term of frequency of the dominace of soecies tended to reveal that occurrence and in number of taxa as summarised structure of benthic community of those sub area as follow. may be similar. Unfortunately, no contirmation could be made since this information derived from As shown above, the crustacea and short period observation only.

153 tnd.Fish Res.J. vot.12 No.2 Desenber-2006: 129-157

Table 5. Density of macrobenthos (ind.m-3) of three sub areas observed on September to December 2005

East of Lam North of Central Java exonom b Sdmararg,a sp. 31394 g Slhu/n EP. 3890 7 S,irurr sp. 12840 Srirum sp. 207 64 b Sgmar€ng,i8 sP. 208 55 b Dorax sp. 1644 sp. 475 s Tuffitella sp. 1591 5 b Codakta sp. 77 80 b Samarcngia Cod8kia sp. 8554 b Oorax sp. 6121 Denlalium sp. 321 b Oorax sp. 4857 g Tut tella sp. 3839 Teuina sp. Nucu/ara sp. b fol/ha sP. 2305 Turile a sp. 246 b Tallina sp. b Earbata sP. 1714 Vepricadium sp. 97 Doslrla 8p. 1783 b Chlarnys sP. 1318 Codakib sp. g Atchit1ctonica sp. 1646 s D€ntal/uft sp. 1121 Nuculana sp. g Pharacovolva sp. 1467 g Phenacovolva sp 936 Phenacovolava sp 40 Avercga no. taxa 20 17 No. taxa recodcd 46 Total Bivalve 43438 2741 Total Gastropoda 42239 46516 13313 Total Scaphopoda 1121 321 Total M alaco6trata Total Polychaeta 24 Romarkst b = bivalve; g = gastropode; s= scaphopoda

coNcLustoN controlled by currents regime. Two major seasons exist in the area over the Java Sea, A wide range of components influences the namely the Northwest and Southeast function system of the Java Sea environment. monsoon. During the Northwest monsoon or S€veral aspects involved in the system are geo rainy season, it undergoes a dilution by morphology, climate, hydrology, biology, and freshwater runoff and river discharge, as well human activities. as a water mixing process with coastal water mass coming from the South China Sea. 1. Physical feature of the Java Sea opens a high Reverse process occurs during the Southeast possibility of a relation to the eastern monsoon or dry season, where high saline Indonesian waters and the northem region. The oceanic water enters this area from the islands surrounding the Java Sea give special eastern and northern through Flores impacts on the materials input and circulation in Sea and Makassar Strait. In general, the the coastal area, The fluvial sediment yield is westerlygoing current which brings the th6 important source determining the substrate oceanic water is more regular and significant type of of sea bed and fertilizing the coastal in influencing the characteristics of the Java waters, The rate of deposition of suspended Sea water. In this case the proportlon of the materials from the Java island is considerably oceanic water in side the Java sea would be high, as being determined by the characteristics greater than those from southern of the South ot morphology, orography, climate, and landuse China Sea and Malacca Strait. of this land. - The second is the inter annual variability's that 2. The Java Sea is an extent of the monsoonal . is a special case due to the change of global climate where the pattern of reversal wind and pattern of climatic system, so called as ENSO. current has been well know. There are 2 It exerts in 2 fashions in term of climatic, it po6sible sources of variability's atfecting the prolongs the period of dry season and then characteristics of th€ Java Sea. followed by decreasing dilution process. In term of hydrographic, it indirectly influences - The first is the regular or seasonal the water exchange in the Java Sea through variability's. ln this case, climate is the main the change of global circulation in the Pacific factor goveming the hydrological properties of Ocean. In the Java Sea its influence can be the Java Sea, through a circulation scheme noticed that the oceanic water mass from

154 Review of Environmental Features of the Java Sea (Sadhotomo. B.J

eastem Indonesian archipelago penetrates species. Specia/ Repoft, Contribution of the farther and occupies in the side the Java Sea Demersal Fisheries Prqect. 4. Mar. Fish. Res longer than during normal years. lnst. GTZ.

3. Circulation scheme in this area generates a Berlage, H. P. 1953. The monsoon currents in the soecific stratification of water mass which is Java Sea and its entrance. Koninklijke well defined by using salinity pattern Magnetisch en Meteorologisch ObseNatorium distribution. The oceanic water invades to the te Batavia, Verhandelingen. 19. 1-28. Batavia: Java Sea in the periods of June to October, Javasche Boekhandel en Drukkert. while the coastal water from the northern region replaces it gradually from November to May. Bird, E. C. F. 1979. Environmental problems The lowest and highest salinity in the middle related. to the coastal dynamics of humids area were observed during February to March kopicaf deltas. Programmatic Workshop on and September or 2 months after the peak of Coasfa/ Ressources Management. Jakarta. 11- the seasons. 15 September 1979. Lembaga llmu Pengetahuan Indonesia-U. N. University. Horizontally, this salinity based stratification would be very important for the repartition of the Boely, T., D. Petit, & M. Potier. 1986. Principaux pelagic fish concentration. The shifting of high resultats de la Campagne Pechindon execut6e saline waler mass can be sought as a factor en mer de Java (mai 1985). J. Rech. Oceanogr.

affecting migratory scheme of the oceanic 11 (1\. 15-17 . pelagic fishes. While a tendency of the occurrence of higher salinity in the near bottom Badan Pusat Statistik.1992; 1993; 1994; 1995. layer in the eastern part would be allowable to Statistik Indonesia. Biro Pusat Statistik (Central explain distribution pattern in the Northwest Bureau of Statistics). monsoon. Delsman, H. C. 1939. Preliminary plankton 4. Generally, high seasonal variation of primary investigation in the Java sea. Treubia. 17. 139- productivity takes place in the coastal areas, 181. while in the otfshore area, there is no significant difference between the 2 major seasons. High Directorate General of Water Resources Dev.- productivity in the near coast area is influenced JICA. 1988. Negara river basin overalt irigation by the input of organic and inorganic materials development plan study. Annex B. Meteo from the main land. hydrological Data Vol.2. Water level and discharge. Rep. lndonesia, Ministry of public Sedentary and demersal communities. The Works. influence of seasonal change of water condition on the spatial distribution of most of demersal Doty, M. S., Rd. E.Soeriaatmadja, & A. Soegiarto. species in the coastal areas is apparent. 1963. Observation on the primary produativity Different assemblage of demersal fishes by of northwestern Indonesian waters. Mar. Rei. areas reveal that each area is occupied by lndon.,5,1-25. different community being charaterized by Dwiponggo, A. & M. Badruddin. cerlain predominance species. Similar trend of 1980. Data trawl survey by RN Mutiara 4 in discrimination of benthic community seem to be the Java Sea area. .Special Repoft. Contibution obvious along coastal area of north of Java. of the Demersal Fisheries Project. 7. Mar. Fish. Res /nst

Durand, J. R. & D. Petit. 1995. The Java Sea REFERENCES environment. /n M. Potier & S. Nurhakim (eds). Seminar on the Eiology, Dynamics, and Allen, G. P., D..Laurier, & J. Thouvenin. 1979. Exploftations. Java Sea Pelagic Fishery Etude sedimentologiquee du detta de ta Assessment Pro_/bct. Jakarta., Mahakam. Note et memoires N. 15. Totat. Compagnie petrols. paris. FranQais de Emery, K. O., E. Uchupi, J. Sunderland, H. L. Uktolseja, & E. M. Young. 1972. ceological Beck, U. & A. Sudradjat. 1979. Variation in size structure and some water characteristics of the and composition of demersal trawl catches from Java Sea and adjacent continental shelft. the norlh coast of Java with estimated growth United Nation. ECAFE. CCOP Tech. Bu. parameters for three important food fish 6,197 -223.

155 129-157 lnd.Fish Res.J. vot 12 No 2 Desember-2006:

1970. Les moussons. 2"d Col/ Freux, M. 1987. Ocean Indien et Mousson Pedelaborde, P. Conf rcnce d la m6moire d'Anton Bruun Colin.208 p. UNESCO. Mars 1987. 15 P Potier, M. 1990. Pecherie de layang et senneurs javanaise: Perspective P., P. G. E, F. Agustinus, & J H J semi tndustriel Hoekstra, These de Terwindt. 1988. River outflow and miud historique et approche systeme. ll. p deoosition in a monsoon dominated coastal doctorat. t)niv. Montpellier 300 environment. ln Dronker, J & van Leussen, W' (eds). Phvsical processes in estuarine /'t Potier. M. & T. Boely l990 lnfluence de sur la peche a la bynip. tne uetnertands. 1986 Spnnger' Berlin parametre de l'environnement et coulissante en Mer de Java 311-331 o. senne tournante Aquatic Living Res 3 193-205. R. 1982. Agroclimatic and dry season Huke, E. W K south, southeast, and east asla Quinn, W. H,, D. O. Zopf' K S. Short, & R T maos of and statistrcs of lntarnational Rice Reasearch lnstitutg' Los Yano. t9i8. Historical trends El Nilio and Indonesian Bailos. The PhiliPinnes. sout-hern oscillation, drought. Fishery 8u\|.76 3 663-678 A. G. 1978. On the factor affecting the llahude, R Durand l99T General oroOuctivity of the Southern Makassar Stralt Sadhotomo,-- B. & J 'Mar. Sea ecology Proceeding of Res. Indonesia 21 81-107 ' ieature of the Java Acousfics Seminar Akustikan 2 EU-AARD- of ORSTOM,43-54 P. llahude, A. G. 1979. On the hydrology - (Southern South China Sea) The Kurosnto P. Martosubroto. & Pauly D 1976 tV Pioc.4th. CSK Symposium Tokyo Saeqer,- J., F'irst report of the Indonesian-German Mulyana' & S' Oimersat Fisheries Project Result of a trawl Karmini, M,, F Renggono, E Fish rain pattern over Java iurvey in the Sunda Shelft area Mar' Nuoroho. 1995. Unsual coo (GTz) reoirdinq Southeast monsoon lnternattonal Cis. ins. ana German Ag Tech w-o*"inip on the throuhflow studies in and 'naoretian waters Jakafta 10-12 Siarif, S. 1959. Seasonal fluctuations in the surface -'-""tinitv coast of the southern part of October"iiria 1995. atong the xalimintan () Mar' Res lndon q de List. 1957 Kastoro, W. W., I Aswandy, A L Hakim' Wielde Ocerlographlc sta -i. n. w. J., & J M Everaarts l9S9 soft '1966 study Loftom community in the estuarine water of Soeqiarto, A. & A Nontji A seasonal .r.u" Proc snellius ll symp Neth J sea oT onrnarv marine productivity in Indonesian Eiii Tokyo Res.23, 463472. wat'ers. Xi th Pacific science congress 7p. the Losse, G. F. & Dwiponggo, A 1977 Report on Java Sea southeast monsoon trawl survey' soeriaatmadja, Rd. E. 1956 Seasonal fluctuations noth coast of Java 1976 Spacial Eeqott. in the su*ace salinity off the iune-Oece.Oet 1959 Connioutio, of the Demersa! Fisheries Proiect . Mar. Res. lndon. 1. 1-19. Sjarif, S surface salinity 3. Mar. Fish. Res. lns.-GTZ Seasonal fluctuations in the alonq the coast of the southern part of lndon 4 Molcard. R,, M. Fieux, & A. G llahude l99S The Kaliriantan (Borneo) Mar' Res Indo Pacifrc throughflow in the Timor passage OcenograPhic sta. List. 1957 tnternationat Workshop on the throuhflow studies ,, and around lndonesian waters' U.S. Navv. 1987. The Ocean basin environment' Jakarta 10-12 October 1995 Oceai Project Div. U. S Naval Qceanographtc Oftice. xx D. Nicholls. N. 1993. ENSO' drought, and flooding Asia /n H Brookfield & Y rain in South-East Preliminary chart of the mean (gds). South East Asia's Environmental Veen, P. C. H. 1953. Brvon. ' Archipelago and puiure. Th6 search for sustainibility Unltad salinitv of the Indonesian adiac;nt waters. Org sci Res lndonesia' Ndtion lJniv. Press. Oxford Univ. Press Tokyo' afu n. aa p. Notes the chlorophyll Nontji, A. 1977. on W Kastoro' E' M distribution around .1"*".'b'"",norogi'di werOe de' P A W J' W --" Aswandy' A L Hakim' & A Kok' lndonesia.7. 4g47. :*- Berghuis' I

156 Review of Enviic'tmental Featw€s ot the Jdva Sea (sadhotomo' B.)

1989. Structure and energy demand of the Perhubungan, Lembaga Meteorolgi, dan benthic soft bottom communities in the Java Geofisika. Sea and around the lsland of Madura and Bali. fndonesia. Natt. J Sea Ras. 23. 449461. Vwrtki, K. 1957. Die zirkulation onder oberflache der Sudostasiatischen Genasser. Deutsch Wyrtki, K. 1956a. Monthly charts of sea surface Hydrographische Zeitschrift. Bdnd 10. Heft 1 salinity in Indoesian and adjacent waters. J. 't-13. ctEM.21.268-279. Wyrbki, K. 1961. Physical Oceanography ofthe the Indonesian South east Asian Waters. Naga Repott.2. 1' Wvrtki.'walerc. K. 1956b. The rainfall over verhandtingen. 49. 1'24 Kementrian 145.

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